CN114035096A

CN114035096A - Electrochemical device SOH evaluation method, electronic device, and battery system

Info

Publication number: CN114035096A
Application number: CN202111432267.4A
Authority: CN
Inventors: 贺国达; 陈英杰
Original assignee: Dongguan Poweramp Technology Ltd
Current assignee: Dongguan Poweramp Technology Ltd
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2022-02-11
Anticipated expiration: 2041-11-29
Also published as: CN114035096B

Abstract

The embodiment of the application provides an electrochemical device health degree SOH assessment method, electronic equipment and a battery system. The method comprises the following steps: performing an intermittent charging operation on the electrochemical device, wherein a reference internal resistance and a lithium deposition SOC of the electrochemical device are obtained in the intermittent charging operation, and the reference internal resistance is used for indicating the internal resistance when the electrochemical device is charged to the first SOC; and determining the SOH of the electrochemical device based on the lithium analysis SOC, the reference internal resistance and a pre-established mapping relation of the lithium analysis SOC-reference internal resistance-SOH. Based on the scheme, the internal resistance and the lithium separation state of the electrochemical device are considered, and the SOH is simultaneously evaluated from two dimensions of the internal resistance and the lithium separation state of the electrochemical device, so that the accuracy of the SOH evaluation of the electrochemical device is improved.

Description

Electrochemical device SOH evaluation method, electronic device, and battery system

Technical Field

The present disclosure relates to the field of electrochemical technologies, and in particular, to a method for evaluating health of an electrochemical device, an electronic device, and a battery system.

Background

The lithium ion battery has the advantages of large specific energy density, long cycle life, high nominal voltage, low self-discharge rate, small volume, light weight and the like, and has wide application in the field of new energy.

With the rapid development of tablet computers, mobile phones, electric vehicles and energy storage devices in recent years, and the continuous development of new energy industries, the market has more and more demands on lithium ion batteries. The reliability and safety of the lithium ion battery are one of the most concerned problems in battery application, and the State of Health (SOH) of the lithium ion battery can be accurately evaluated and predicted, so that the internal hidden danger and the service life condition of the electrochemical device can be judged, and reference can be provided for maintenance and replacement of the electrochemical device. Therefore, how to accurately evaluate and predict the health degree of the lithium ion battery becomes a problem to be solved urgently.

Disclosure of Invention

An object of the embodiments of the present application is to provide a method for estimating SOH of an electrochemical device, an electronic apparatus, and a battery system, so as to improve accuracy of estimating SOH of an electrochemical device.

According to a first aspect of embodiments herein, there is provided an electrochemical device SOH evaluation method, comprising: performing an intermittent charging operation on the electrochemical device, in which a reference internal resistance and a lithium evolution SOC of the electrochemical device are obtained, the reference internal resistance being indicative of an internal resistance when the electrochemical device is charged to a first SOC; and determining the SOH of the electrochemical device based on the lithium analysis SOC, the reference internal resistance and a pre-established mapping relation of the lithium analysis SOC-reference internal resistance-SOH. Since the internal resistance and the lithium deposition state of the electrochemical device are taken into consideration and the SOH is estimated from two dimensions of the internal resistance and the lithium deposition state of the electrochemical device at the same time, the accuracy of SOH estimation of the electrochemical device is improved.

In one embodiment of the present application, after determining the SOH of the electrochemical device based on the lithium deposition SOC, the reference internal resistance, and a pre-established mapping relationship of lithium deposition SOC-reference internal resistance-SOH, the method further comprises: and correcting the SOH. By correcting the SOH, a large deviation of the SOH can be avoided, and thereby the calculation accuracy of the SOH can be further improved.

In one embodiment of the present application, prior to the intermittent charging operation of the electrochemical device, the method further comprises: acquiring the current charge-discharge cycle number of the electrochemical device; the correcting the SOH comprises: and correcting the SOH according to the current charge-discharge cycle number. The SOH is corrected based on the current charge and discharge cycle number, so that the SOH can be estimated from three dimensions of the current charge and discharge cycle number, lithium deposition and internal resistance, and the calculation accuracy of the SOH is improved.

In one embodiment of the present application, the correcting the SOH according to the current charge and discharge cycle number includes: determining the SOH corresponding to the current charge-discharge cycle number according to the current charge-discharge cycle number and a pre-established charge-discharge cycle number-SOH mapping relation; determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number; and correcting the SOH by using the SOH allowable range.

In one embodiment of the present application, the determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number includes: determining the lower limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number minus a first positive error; and determining the upper limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number plus a first positive error. Thereby, the SOH allowable range is determined in a simpler manner.

In one embodiment of the present application, the first positive error ranges from 0% to 5%.

In one embodiment of the present application, said modifying said SOH using said SOH allowance range comprises: if the SOH is larger than the upper limit value of the SOH allowable range, correcting the SOH to the upper limit value; and if the SOH is smaller than the lower limit value of the SOH allowable range, correcting the SOH to be the lower limit value. Therefore, the SOH determined based on the lithium analysis SOC and the reference internal resistance is limited within the SOH allowable range, large deviation in the calculation process of the SOH is avoided, and the calculation accuracy of the SOH is improved.

In one embodiment of the present application, the method is performed on a periodic basis, and the modifying the SOH comprises: and correcting the SOH based on the SOH determined in the last period. By correcting the SOH determined in the current period by using the SOH determined in the previous period, obvious errors which may occur when the SOH is determined in the current period can be eliminated in a simpler manner, and the accuracy of SOH estimation is improved.

In one embodiment of the present application, the modifying the SOH based on the SOH determined in the previous cycle comprises at least one of: if the SOH is larger than the SOH determined in the previous period, correcting the SOH to be the SOH determined in the previous period; or if the SOH is less than the SOH determined for the previous cycle minus a second positive error, correcting the SOH to the SOH determined for the previous cycle minus the second positive error.

In one embodiment of the present application, the second positive error ranges from 0.01% to 0.1%.

In one embodiment of the present application, the intermittent charging includes a plurality of charging periods and a plurality of intermittent periods, the intermittent charging operation of the electrochemical device in which the reference internal resistance and the lithium deposition SOC of the electrochemical device are obtained includes: obtaining an internal resistance and SOC of the electrochemical device during the interruption; obtaining a first curve based on the SOC and the internal resistance during each interruption, the first curve representing a variation of the internal resistance with the SOC; based on the first curve, the lithium deposition SOC is determined, and based on the first curve, the reference internal resistance is determined.

In one embodiment of the present application, the determining the lithium extraction SOC based on the first curve includes at least one of a manner a1 and a manner a 2. The mode a1 includes: differentiating the first curve to obtain a first differential curve; determining whether the first differential curve has a maximum value and a minimum value; and if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as the lithium analysis SOC. The mode a2 includes: differentiating the first curve to obtain a first differential curve; differentiating the first differential curve to obtain a second differential curve; and determining the SOC corresponding to the point where the ordinate of the second differential curve is less than zero for the first time as the lithium analysis SOC.

In one embodiment of the present application, the mapping relationship between the lithium analysis SOC-reference internal resistance-SOH is pre-established by: obtaining a sample electrochemical device set; performing an intermittent charging operation on sample electrochemical devices in the set of sample electrochemical devices, in which a reference internal resistance and a lithium evolution SOC of the sample electrochemical devices are obtained; calibrating the SOH of the sample electrochemical device; and establishing a mapping relation of the lithium analysis SOC-reference internal resistance-SOH based on the reference internal resistance and the lithium analysis SOC of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

In one embodiment of the present application, the pre-established charge-discharge cycle number-SOH mapping relationship is pre-established by: obtaining a number of charge-discharge cycles of a sample electrochemical device of the set of sample electrochemical devices prior to performing an intermittent charging operation on the sample electrochemical device; and establishing a charge-discharge cycle number-SOH mapping relation based on the charge-discharge cycle number and the calibrated SOH of each sample electrochemical device in the sample electrochemical device set.

According to a second aspect of embodiments herein, there is provided a battery system comprising a processor, a machine-readable storage medium, and a sensor for detecting at least one of pressure or temperature of an electrochemical device, the machine-readable storage medium storing machine-executable instructions executable by the processor, the processor when executing the machine-executable instructions implementing the method of any one of the preceding first aspects.

According to a third aspect of embodiments of the present application, there is provided an electronic apparatus, including: comprising the battery system of the second aspect.

According to a fourth aspect of embodiments of the present application, there is provided an electronic apparatus, including: a lithium analysis SOC analysis device and an SOH determination device. The lithium evolution SOC analysis device is used for carrying out intermittent charging operation on the electrochemical device, and obtaining reference internal resistance and lithium evolution SOC of the electrochemical device in the intermittent charging operation, wherein the reference internal resistance is used for indicating the internal resistance when the electrochemical device is charged to the first SOC. The SOH determining device is used for determining the SOH of the electrochemical device based on the lithium analysis SOC, the reference internal resistance and a pre-established mapping relation of the lithium analysis SOC to the reference internal resistance to the SOH. Since the internal resistance and the lithium deposition state of the electrochemical device are taken into consideration and the SOH is estimated from two dimensions of the internal resistance and the lithium deposition state of the electrochemical device at the same time, the accuracy of SOH estimation of the electrochemical device is improved.

In one embodiment of the present application, the electronic apparatus further includes SOH correction means for correcting the SOH after determining the SOH of the electrochemical device based on the lithium deposition SOC, the reference internal resistance, and a pre-established mapping relationship of lithium deposition SOC-reference internal resistance-SOH. By correcting the SOH, a large deviation of the SOH can be avoided, and thereby the calculation accuracy of the SOH can be further improved.

In one embodiment of the present application, the electronic apparatus further includes an acquiring device configured to acquire a current number of charge and discharge cycles of the electrochemical device before the electrochemical device is subjected to the intermittent charging operation. The SOH correction device is specifically configured to correct the SOH according to the current charge-discharge cycle number. The SOH is corrected based on the current charge and discharge cycle number, so that the SOH can be estimated from three dimensions of the current charge and discharge cycle number, lithium deposition and internal resistance, and the calculation accuracy of the SOH is improved.

In an embodiment of the present application, the SOH correction apparatus is specifically configured to: determining the SOH corresponding to the current charge-discharge cycle number according to the current charge-discharge cycle number and a pre-established charge-discharge cycle number-SOH mapping relation; determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number; and correcting the SOH by using the SOH allowable range.

In an embodiment of the present application, the SOH correction apparatus is specifically configured to: determining the lower limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number minus a first positive error; and determining the upper limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number plus a first positive error. Thereby, the SOH allowable range is determined in a simpler manner.

In an embodiment of the present application, the SOH correction apparatus is specifically configured to: if the SOH is larger than the upper limit value of the SOH allowable range, correcting the SOH to the upper limit value; and if the SOH is smaller than the lower limit value of the SOH allowable range, correcting the SOH to be the lower limit value. Therefore, the SOH determined based on the lithium analysis SOC and the reference internal resistance is limited within the SOH allowable range, large deviation in the calculation process of the SOH is avoided, and the calculation accuracy of the SOH is improved.

In one embodiment of the present application, the SOH determining means is specifically configured to determine the SOH periodically; the SOH correction apparatus is specifically configured to correct the SOH based on the SOH determined in the previous cycle. By correcting the SOH determined in the current period by using the SOH determined in the previous period, obvious errors which may occur when the SOH is determined in the current period can be eliminated in a simpler manner, and the accuracy of SOH estimation is improved.

In an embodiment of the present application, the SOH correction apparatus is specifically configured to perform at least one of the following: if the SOH is larger than the SOH determined in the previous period, correcting the SOH to be the SOH determined in the previous period; or if the SOH is less than the SOH determined for the previous cycle minus a second positive error, correcting the SOH to the SOH determined for the previous cycle minus the second positive error.

In an embodiment of the present application, the lithium deposition SOC analyzing apparatus is specifically configured to: obtaining an internal resistance and SOC of the electrochemical device during the interruption; obtaining a first curve based on the SOC and the internal resistance during each interruption, the first curve representing a variation of the internal resistance with the SOC; determining the lithium deposition SOC based on the first curve, and determining the reference internal resistance based on the first curve.

In an embodiment of the present application, the lithium deposition SOC analyzing apparatus is specifically configured to: at least one of the manner a1 and the manner a2 is performed. The mode a1 includes: differentiating the first curve to obtain a first differential curve; determining whether the first differential curve has a maximum value and a minimum value; and if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as the lithium analysis SOC. The mode a2 includes: differentiating the first curve to obtain a first differential curve; differentiating the first differential curve to obtain a second differential curve; and determining the SOC corresponding to the point where the ordinate of the second differential curve is less than zero for the first time as the lithium analysis SOC.

According to the electrochemical device SOH evaluation method, the electronic equipment and the battery system, the electrochemical device is subjected to intermittent charging operation, the reference internal resistance and the lithium precipitation SOC of the electrochemical device are obtained in the intermittent charging operation, and the SOH of the electrochemical device is determined based on the lithium precipitation SOC, the reference internal resistance and the pre-established mapping relation of the lithium precipitation SOC-the reference internal resistance-the SOH, so that the internal resistance and the lithium precipitation state of the electrochemical device are considered, and the SOH is evaluated from two dimensions of the internal resistance and the lithium precipitation state of the electrochemical device at the same time, and the accuracy of the SOH evaluation of the electrochemical device is improved.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the description of the embodiments of the present application will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the embodiments of the present application, and it is also possible for those skilled in the art to obtain other drawings based on these drawings.

FIG. 1 is a flow chart illustrating the steps of a method for assessing the SOH of an electrochemical device according to an embodiment of the present application;

FIG. 2 is an exemplary flowchart of step 110 according to an embodiment of the present application;

FIG. 3 is a flow chart illustrating steps in another method for estimating SOH of an electrochemical device according to an embodiment of the present disclosure;

FIG. 4 is an exemplary flowchart of step 114 according to an embodiment of the present application;

FIG. 5 is a diagram illustrating the relationship between SOH and an allowable range of SOH determined based on a lithium analysis SOC and a reference internal resistance according to an embodiment of the present application;

FIG. 6 is a flow chart illustrating steps in another method for estimating SOH of an electrochemical device according to an embodiment of the present disclosure;

fig. 7 is an exemplary flowchart of step 116 of an embodiment of the present application.

FIG. 8 is a flowchart illustrating steps of a process for establishing a mapping relationship between a lithium analysis SOC and a reference internal resistance-SOH, and a mapping relationship between a number of charge and discharge cycles and an SOH according to an embodiment of the present application;

FIG. 9 is a flowchart illustrating steps in a process for establishing an exemplary lithium analysis SOC-reference internal resistance-SOH mapping relationship and charge-discharge cycle number-SOH mapping relationship according to an embodiment of the present application;

FIG. 10 is a block diagram of an electronic device according to an embodiment of the present application;

fig. 11 is a block diagram of a charging device according to an embodiment of the present application; and

fig. 12 is a block diagram of a battery system according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is further described in detail below with reference to the accompanying drawings and examples. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other technical solutions obtained by a person of ordinary skill in the art based on the embodiments in the present application belong to the scope of protection of the present application.

The following description will first describe a specific implementation of the embodiments of the present application with reference to the drawings.

In the contents of the embodiments of the present application, the present application is exemplified by a lithium ion battery as an example of an electrochemical device, but the electrochemical device of the present disclosure is not limited to a lithium ion battery.

The embodiment of the application provides an electrochemical device health SOH assessment method, and an execution subject of the method can be a Battery Management System (BMS). As shown in fig. 1, the method comprises the steps of:

step 110: an intermittent charging operation is performed on the electrochemical device, in which a reference internal resistance and a State of Charge (SOC) of the electrochemical device are acquired.

In an embodiment of the present application, the reference internal resistance is used to indicate a corresponding one of the internal resistance values when the electrochemical device is charged to the first SOC during the intermittent charging. The first SOC may be 50%. It should be understood that 40%, 60%, or any other suitable SOC may be selected as the first SOC, and the present embodiment is not limited thereto. The lithium evolution SOC may refer to an SOC associated with a lithium evolution state of the electrochemical device. The smaller the lithium evolution SOC, the more serious the lithium evolution state.

In the embodiment of the present application, the intermittent charging operation may refer to a process of performing an intermittent charging operation on the electrochemical device. In particular, in one implementation, the intermittent charging operation includes a plurality of charging periods and a plurality of intermittent periods. Illustratively, the electrochemical device is charged during a first charging period and then stopped, and after a first break period, the electrochemical device continues to be charged during a second charging period, and so on, until the SOC of the electrochemical device reaches a first threshold. It is understood that as the SOC of the electrochemical device increases as the intermittent charging proceeds, the embodiment of the present application may stop the intermittent charging when the SOC of the electrochemical device reaches the first threshold value, and complete the intermittent charging operation. The first critical value is not particularly limited in the embodiments of the present application as long as the object of the present application can be achieved, and for example, the first critical value may be 60%, 70%, 80%, 90%, or 100%. The charging method in the intermittent charging operation is not particularly limited in the embodiments of the present application, and may be constant voltage charging, constant current and constant voltage charging, or segmented constant current charging, as long as the purpose of the embodiments of the present application can be achieved.

Referring to fig. 2, in one implementation, step 110 includes:

step 1101, acquiring the internal resistance and SOC of the electrochemical device during the interruption period.

In the embodiment of the present application, in the intermittent charging operation, the internal resistance of the electrochemical device may be determined based on the terminal voltage and the charging current of the electrochemical device detected during each interruption.

The description will be given taking as an example the determination of the internal resistance of the electrochemical device during the present interruption. Specifically, a first terminal voltage of the electrochemical device at a starting time point of the intermission period and a second terminal voltage at an ending time point of the intermission period are acquired (e.g., acquired by an Analog Front End (AFE) of the BMS), a voltage difference between the first terminal voltage and the second terminal voltage is determined, and an internal resistance of the electrochemical device is determined based on the voltage difference and a charging current of the electrochemical device detected during charging.

In the embodiment of the present application, for the intermittent charging operation, the SOC of the electrochemical device may be determined based on a voltage-SOC relation table stored in advance. For example, a voltage-SOC relation table may be stored in advance in the BMS, and the SOC of the electrochemical device corresponding to different terminal voltages is recorded in the voltage-SOC relation table, for example, 4.2V corresponds to 85% SOC, and 4.3V corresponds to 90% SOC. Thus, in the intermittent charging operation, after the terminal voltage of the electrochemical device at the end time point of the current intermittent period is acquired, the SOC of the electrochemical device can be determined based on the terminal voltage and the voltage-SOC relation table. It should be understood that the SOC of the electrochemical device may also be determined based on the terminal voltage of the electrochemical device at the starting time point of the current interruption period and the voltage-SOC relation table, which is not limited in this embodiment.

Step 1102, obtain a first curve based on the SOC and the internal resistance during each of the discontinuities.

In the embodiment of the application, after the SOC and the internal resistance of the electrochemical device during each discontinuous period are obtained, a data pair consisting of a plurality of SOCs and internal resistances can be obtained, the SOC of the electrochemical device can be used as an abscissa, the internal resistance of the electrochemical device can be used as an ordinate, points represented by the data pairs are filled in a coordinate system, and a first curve is obtained after fitting, wherein the first curve represents the change of the internal resistance of the electrochemical device along with the SOC.

It can be understood that the more intensive the SOC and internal resistance data of the electrochemical device are collected, the more data pairs are obtained, and the more detailed first curve can be obtained. The process of curve fitting using the data is well known to those skilled in the art, and the embodiment of the present application is not particularly limited thereto.

Step 1103, determining a lithium analysis SOC based on the first curve, and determining a reference internal resistance based on the first curve.

In the embodiment of the present application, since the first curve represents a variation of the internal resistance with the SOC, determining the reference internal resistance based on the first curve may include: and determining a target point when the SOC is the first SOC on the first curve, and taking the internal resistance value of the target point as the reference internal resistance, so that the reference internal resistance of the electrochemical device can be accurately determined by a simpler method. It should be understood that the reference internal resistance may also be determined by calculating a ratio of voltage to current according to the terminal voltage and the charging current when the electrochemical device is charged to the first SOC, which is not limited by the present embodiment.

In the embodiment of the present application, determining the lithium analysis SOC based on the first curve may be implemented in various ways. Two specific implementations are exemplified below.

In one particular implementation, the process of determining the lithium evolution SOC based on the first curve may be manner a 1. Mode a1 includes:

and A11, differentiating the first curve to obtain a first differential curve.

Since the first curve represents the variation of the internal resistance R of the electrochemical device with the SOC of the electrochemical device, the first differential curve obtained by differentiating the first curve, that is, the first differential curve, is the first-order differential curve of the first curve, which actually represents the rate of change of the internal resistance R of the electrochemical device with the SOC.

Step a12, determining whether the first derivative curve has a maximum and a minimum.

In a mathematical sense, when the first differential curve has a maximum value and a minimum value at the same time, it indicates that the original flat region on the first differential curve has a relatively obvious fluctuation, i.e. an abnormal reduction. In the embodiment of the present application, the first differential curve represents the rate of change of the internal resistance of the electrochemical device with respect to the SOC. When the rate of change did not decrease abnormally in the flat area of the curve, it indicates that the electrochemical device did not precipitate active lithium. When the change rate is abnormally reduced in the flat region of the curve, active lithium is precipitated on the surface of the negative electrode and is in contact with the negative electrode, namely the graphite part of the negative electrode is connected with a lithium metal device in parallel, so that the impedance of the whole negative electrode part is reduced, the internal resistance of the electrochemical device is abnormally reduced when the active lithium is precipitated, and correspondingly, the flat region of the first differential curve is abnormally reduced.

And A13, if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as a lithium analysis SOC.

When both the maximum value and the minimum value exist, the electrochemical device is indicated to have a lithium precipitation tendency or already have lithium precipitation at the maximum value, and the SOC corresponding to the maximum value is determined as the lithium precipitation SOC so as to reasonably determine the lithium precipitation SOC of the electrochemical device, which is beneficial to subsequently evaluating or predicting the SOH of the electrochemical device according to the lithium precipitation SOC and improving the use safety of the electrochemical device.

In this other specific implementation, the process of determining the lithium deposition SOC based on the first curve may be manner a 2. Mode a2 includes:

and step A21, differentiating the first curve to obtain a first differential curve.

The step a21 is the same as the step a11, and can be understood with reference to the step a11, which is not described herein again.

And step A22, differentiating the first differential curve to obtain a second differential curve.

The second differential curve can be understood to be a second-order differential curve of the first curve

And A23, determining the SOC corresponding to the point where the ordinate of the second differential curve is less than zero for the first time as the lithium analysis SOC.

And if the ordinate of the second differential curve is less than zero, determining the SOC corresponding to the point where the ordinate of the second differential curve is less than zero for the first time as the lithium analysis SOC.

It should be understood that the above two specific implementations of determining the lithium analysis SOC are only used as alternative implementations, and are not limitations on the embodiments of the present application.

In the embodiment of the present application, step 110 may be performed by the lithium analysis SOC analysis device. The lithium deposition SOC analysis device 1010 according to the embodiment of the present application is not particularly limited as long as an intermittent charging operation can be realized. For example, the lithium deposition SOC analysis device 1010 may be a controller Unit (MCU) in a Battery Management System (BMS) board. The operation of the process shown above is for illustration purposes only.

Step 102: and determining the SOH of the electrochemical device based on the lithium analysis SOC, the reference internal resistance and a pre-established mapping relation of the lithium analysis SOC-reference internal resistance-SOH.

Specifically, the SOH of an electrochemical device characterizes the current electrochemical device's ability to store electrical energy relative to a new electrochemical device, and represents the state of the electrochemical device from the beginning to the end of its life in percent, which is used to quantitatively describe the current performance state of the electrochemical device.

The mapping relation of lithium analysis SOC-reference internal resistance-SOH is used for indicating the change relation of SOH along with lithium analysis SOC and internal resistance. The smaller the lithium deposition SOC, the more serious the lithium deposition degree, and the smaller the SOH of the electrochemical device. Meanwhile, the greater the internal resistance of the electrochemical device, the smaller the SOH of the electrochemical device. That is, as the lithium deposition SOC is smaller, the internal resistance is larger, and the SOH of the electrochemical device is smaller. The mapping relation of lithium analysis SOC-reference internal resistance-SOH is established in advance, and the specific establishing process is explained in detail in the following embodiment. The mapping relationship of the lithium analysis SOC to the reference internal resistance to the SOH may be stored in advance in an internal storage device of the BMS, or may be stored in another storage device accessible to the BMS, from which the BMS retrieves when in use.

In a specific implementation manner, the mapping relationship of the lithium analysis SOC-reference internal resistance-SOH includes at least one lithium analysis SOC, at least one reference internal resistance, and at least one SOH corresponding to the at least one lithium analysis SOC and the at least one reference internal resistance. Referring to table 1, table 1 is a mapping relationship of an exemplary lithium analysis SOC-reference internal resistance-SOH provided in an embodiment of the present application, and the table records a plurality of lithium analysis SOCs, a plurality of reference internal resistances, and SOH corresponding to each lithium analysis SOC and reference internal resistance.

TABLE 1

As can be seen from table 1, when the reference internal resistance is constant, the lithium deposition SOC gradually decreases from left to right, and the SOH gradually decreases. When the lithium separation SOC is fixed, the reference internal resistance is gradually increased from top to bottom, and each SOH is gradually reduced. That is, the smaller the lithium precipitation SOC is, the smaller the corresponding SOH is; the larger the reference internal resistance, the smaller the corresponding SOH. It should be understood that table 1 is only one example for illustrating the mapping relationship of the lithium analysis SOC-reference internal resistance-SOH, and the interval value between the lithium analysis SOC and the reference internal resistance in table 1 may be set according to actual needs, and the embodiment of the present application is not particularly limited.

In one embodiment of the present application, when determining the SOH, the lithium analysis SOC and the reference internal resistance closest to the current lithium analysis SOC and the current reference internal resistance in the mapping relationship may be determined as the target lithium analysis SOC and the target reference internal resistance, and then the SOH may be determined based on the target lithium analysis SOC and the target reference internal resistance lookup table, whereby the SOH of the electrochemical device may be determined at a faster speed. And the current lithium analysis SOC and the current reference internal resistance are respectively the current moment, the electrochemical device is subjected to intermittent charging operation, and the reference internal resistance and the lithium analysis SOC of the electrochemical device are obtained in the intermittent charging operation. In another embodiment of the present application, when determining the SOH, the SOH may be determined based on a linear difference between the two lithium deposition SOCs and the reference internal resistance, which are close to the current lithium deposition SOC and the current reference internal resistance, whereby the SOH of the electrochemical device may be more accurately determined.

In the embodiment of the application, the reference internal resistance and the lithium deposition SOC of the electrochemical device are obtained in the intermittent charging operation by carrying out the intermittent charging operation on the electrochemical device, and the SOH of the electrochemical device is determined based on the lithium deposition SOC, the reference internal resistance and the pre-established mapping relation of the lithium deposition SOC-the reference internal resistance-the SOH, so that the internal resistance and the lithium deposition state of the electrochemical device are considered, and the SOH is evaluated from two dimensions of the internal resistance and the lithium deposition state of the electrochemical device at the same time, and the accuracy of the SOH evaluation of the electrochemical device is improved.

In one embodiment of the present application, the method further comprises: the SOH is corrected.

Since there may be a large deviation between the obtained lithium deposition SOC and the reference internal resistance due to disturbance or calculation error in the SOH determination process through

steps

110 and 112, and further there may be a large deviation in the determined SOH, the SOH is corrected to reduce the large deviation in the SOH, so that the calculation accuracy of the SOH can be further improved.

Specifically, as shown in fig. 3, in one implementation of the present application, before performing the intermittent charging operation on the electrochemical device, the method further includes: and step 111, acquiring the current charge-discharge cycle number of the electrochemical device. Accordingly, correcting the SOH includes: and step 114, correcting the SOH according to the current charge-discharge cycle number.

The charge-discharge cycle may be described as a cycle in which the electrochemical device is fully charged and fully discharged once. During the use of the electrochemical device, when the electrochemical device reaches a complete charge cycle, i.e., the electrochemical device is fully charged and fully discharged, the number of charge and discharge cycles of the electrochemical device increases by 1. The number of charge and discharge cycles may be stored in an internal storage device of the electrochemical device so that the number of charge and discharge cycles is read from the internal storage device by the BMS of the electrochemical device, when necessary.

Generally, an electrochemical device has a certain charge/discharge life, i.e., the number of charge/discharge cycles that the electrochemical device can perform at a certain capacity. The SOH of the electrochemical device gradually decreases as the number of charge and discharge cycles increases. Therefore, the current number of charge and discharge cycles may reflect the SOH of the electrochemical device to some extent. The SOH is corrected based on the current charge and discharge cycle number, so that the SOH can be estimated from three dimensions of the current charge and discharge cycle number, lithium deposition and internal resistance, and the calculation accuracy of the SOH is improved.

As shown in fig. 4, in a specific implementation, step 114 includes:

step 114a1 is to determine the SOH corresponding to the current charge-discharge cycle number based on the current charge-discharge cycle number and a pre-established charge-discharge cycle number-SOH mapping relationship.

Step 114a2 determines the SOH allowable range based on the SOH corresponding to the current charge/discharge cycle number.

Step 114A3, the SOH is corrected by using the SOH allowable range.

The following describes the steps 114A1 to 114A3 in detail.

At step 114a1, the SOH corresponding to the current charge/discharge cycle number is determined from the current charge/discharge cycle number and a pre-established charge/discharge cycle number-SOH mapping relationship.

The charge-discharge cycle number-SOH map is used to indicate the SOH as a function of the charge-discharge cycle number. The higher the number of charge-discharge cycles, the smaller the SOH. The charge/discharge cycle number-SOH mapping relationship is established in advance, and the specific establishment process is described in detail in the following examples. The map of the number of charge and discharge cycles to SOH may be stored in advance in an internal storage device of the BMS, or may be stored in another storage device accessible to the BMS, and retrieved from the storage device by the BMS when in use.

In a specific implementation, the charge-discharge cycle number-SOH mapping relationship includes a mapping relationship of at least one charge-discharge cycle number and at least one SOH corresponding to at least one charge-discharge cycle number. Referring to table 2, table 2 is a mapping relationship of an exemplary number of charge and discharge cycles to SOH provided in an example of the present application, and a plurality of numbers of charge and discharge cycles and SOH corresponding to each number of charge and discharge cycles are recorded in the table.

TABLE 2

As can be seen from table 2, the number of charge/discharge cycles gradually increases from left to right, and SOH corresponding to each number of charge/discharge cycles gradually decreases. In addition, the SOH change corresponding to the initial stage of use of the electrochemical device (i.e., the number of charge-discharge cycles is relatively small) is slow, and the SOH change corresponding to the final stage of use of the electrochemical device is rapid. It should be understood that table 2 is only an example for explaining the mapping relationship between the number of charge-discharge cycles and SOH, the interval value of the number of charge-discharge cycles in table 2 may be set according to actual needs, and the embodiment of the present application is not particularly limited.

In one embodiment of the present application, when determining the SOH corresponding to the current number of charge and discharge cycles, the number of charge and discharge cycles closest to the current number of charge and discharge cycles in the mapping relationship may be determined as a target number of charge and discharge cycles, and then the SOH corresponding to the current number of charge and discharge cycles may be determined based on a look-up table of the target number of charge and discharge cycles, so that the SOH corresponding to the current number of charge and discharge cycles may be determined relatively quickly. In another embodiment of the present application, in determining the SOH corresponding to the current number of charge and discharge cycles, the SOH corresponding to the current number of charge and discharge cycles may be determined by performing linear interpolation based on two numbers of charge and discharge cycles close to the current number of charge and discharge cycles, so that the SOH corresponding to the current number of charge and discharge cycles is more accurately determined.

In step 114a2, the SOH allowable range is determined based on the SOH corresponding to the current number of charge/discharge cycles.

During use, the SOH of an electrochemical device is affected by various factors such as the temperature of the application environment, the charge/discharge rate, and the charge/discharge depth, and varies, for example, within a certain allowable range, for the same number of charge/discharge cycles. In order to take the influence of various possible factors into consideration, the SOH allowable range is determined based on the SOH corresponding to the current charge-discharge cycle number so as to subsequently correct the SOH using the SOH allowable range, thereby enabling the SOH estimation method provided by the present embodiment to be applicable to various operating conditions.

Specifically, in one implementation of the present application, determining the SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number includes: determining the lower limit value of the allowable range of the SOH as the SOH corresponding to the current charge-discharge cycle number minus a first positive error; the SOH allowable range is determined in a simpler manner as shown in fig. 5 by determining the upper limit value of the SOH allowable range as the SOH corresponding to the current number of charge-discharge cycles plus the first positive error.

Wherein, the range of the first positive error can be 0% -5%. In one embodiment, the first positive error may be 3% to determine a reasonable SOH tolerance range for various operating conditions.

It should be understood that the SOH allowable range may be determined in other manners based on the SOH corresponding to the current charge and discharge cycle number, which is not limited in the embodiment of the present application.

In step 114a3, the SOH is corrected using the SOH allowable range.

Specifically, in one implementation, if the SOH is greater than the upper limit value of the SOH allowable range, the SOH is corrected to the upper limit value of the SOH allowable range; and if the SOH is smaller than the lower limit value of the SOH allowable range, correcting the SOH to be the upper limit value of the SOH allowable range. As shown in FIG. 5, the thin solid line represents SOH (from SOH) determined based on the lithium deposition SOC and the reference internal resistance_R-LPIndicated), and the thick solid line indicates SOH (indicated by SOH) corresponding to the number of charge-discharge cycles_cycleIndicated), the dotted line indicates the SOH allowable range. As shown in FIG. 5, the SOH determined based on the lithium analysis SOC and the reference internal resistance is limited within the allowable range of SOH, avoiding a large bias occurring in the calculation of SOHPoor, improving the calculation accuracy of SOH.

It should be understood that the SOH allowable range may be utilized, and the SOH may be modified in other feasible manners, which is not limited by the embodiment of the present application.

In the embodiment of the application, the SOH of the electrochemical device can be reflected to a certain extent by the number of the charge and discharge cycles, and the SOH is corrected based on the current number of the charge and discharge cycles, so that the SOH is estimated from three dimensions of the current number of the charge and discharge cycles, lithium deposition and internal resistance, and the calculation accuracy of the SOH is provided.

In one embodiment of the present application, the electrochemical device SOH evaluation method shown in fig. 1 and/or fig. 4 is performed on a periodic basis. For example, the electrochemical device performs the SOH evaluation method of the electrochemical device once per charge-discharge cycle. Accordingly, in the embodiment shown in FIG. 6, correcting the SOH further comprises: step 116, correcting the SOH based on the SOH determined in the previous period. Since the SOH of the electrochemical device is gradually reduced along with the increase of the number of charge and discharge cycles in the use process of the electrochemical device, the SOH determined in the previous period is used for correcting the SOH determined in the current period, so that obvious errors which may occur when the SOH is determined in the current period can be eliminated in a simpler mode, and the accuracy of SOH estimation is improved.

Specifically, as shown in fig. 7, in a specific implementation, step 116 may include:

step 116A, if the SOH is greater than the SOH determined in the previous period, the SOH is corrected to the SOH determined in the previous period.

Namely, the SOH determined in the previous period replaces the SOH determined in the current period, the rising SOH determined in the current period is directly removed, obvious errors which may occur when the SOH is determined in the current period are eliminated in a simple mode, and the accuracy of SOH estimation is improved.

With continued reference to fig. 7, in a specific implementation, step 116 may further include:

step 116B, if the SOH is less than the SOH determined in the previous cycle minus the second positive error, the SOH is corrected to the SOH determined in the previous cycle minus the second positive error.

Generally, the SOH of an electrochemical device is gradually decreased as the electrochemical device is used. The SOH of the electrochemical device is slowly decreased at the early stage of the use of the electrochemical device, and is rapidly decreased at the end stage of the use of the electrochemical device. However, even at the end of the use of the electrochemical device, the rate at which the SOH of the electrochemical device decreases does not exceed a certain value. That is, the difference in the SOH determined for two adjacent cycles should be less than the second positive error. For example, the SOH difference may be 0.1%. It should be understood that the SOH difference may be other values between 0.01% and 0.1%, such as 0.05, which is not limited in this embodiment.

If the SOH determined by the two adjacent periods is larger than the second positive error, the SOH determined by the current period has larger deviation. The SOH determined in the current period is corrected to be the SOH determined in the previous period minus the second positive error, so that the SOH determined in the current period and possibly having larger deviation can be directly eliminated, and the problem that the SOH of the electrochemical device is changed greatly in two adjacent periods due to interference and calculation errors is avoided, so that a user can question the quality of the electrochemical device.

In the embodiment of the present application, the step 116 includes both the step 116A and the step 116B to improve the calculation accuracy of the SOH of the electrochemical device. It should be understood that in other embodiments, step 116 may include only step 116A, or only step 116B, which is not limited by the present embodiment. In addition, in order to avoid redundancy, fig. 6 shows that step 114 to step 116 are included in the step of correcting the SOH, and it should be understood that in other embodiments, the step 116 may be included only in the step of correcting the SOH, and this embodiment is not limited thereto.

Fig. 8 is a flowchart illustrating steps of a process of establishing a mapping relationship between lithium analysis SOC-reference internal resistance-SOH according to an embodiment of the present application. As shown in fig. 8, the method includes:

step 810, obtain a sample electrochemical device set.

In an embodiment of the present application, the set of sample electrochemical devices includes N sample electrochemical devices, N being an integer greater than or equal to 1. Each of the N sample electrochemical devices is the same as the electrochemical device type, performance, and the like in the embodiments of the present application.

And 812, performing an intermittent charging operation on the sample electrochemical devices in the sample electrochemical device set, and acquiring the reference internal resistance and the lithium precipitation SOC of the sample electrochemical devices in the intermittent charging operation.

In the embodiment of the present application, before performing the intermittent charging operation on the N sample electrochemical devices in the sample electrochemical device set, the N sample electrochemical devices are subjected to the charge and discharge cycle operation for the preset number of times under the M operating conditions. After the preset number of charge-discharge cycle operations are completed, an intermittent charging operation is performed on each sample electrochemical device, and the reference internal resistance and the lithium precipitation SOC of each sample electrochemical device are obtained in the intermittent charging operation.

The M operating conditions can comprise combinations of different charging and discharging multiplying powers, different charging and discharging depths and different environmental temperatures. One sample electrochemical device corresponds to one operation condition, and M is a positive integer greater than or equal to 1 and less than or equal to N.

The preset number of times may be set as needed, and the performance of the sample electrochemical device gradually decreases as the number of cycles increases. Since the intermittent charging operation is performed on each sample electrochemical device each time after the preset number of charge-discharge cycle operations are completed, the reference internal resistance and the lithium deposition SOC of each sample electrochemical device are obtained in the intermittent charging operation. Therefore, under the condition that the total cycle number is fixed, the smaller the preset times is, the more the reference internal resistance and the lithium analysis SOC of the obtained sample electrochemical device are, and the more accurate the lithium analysis SOC-reference internal resistance-SOH mapping relation is determined in the follow-up process. In the embodiment of the present application, the preset number of times may be between 50 and 200. In one embodiment, the predetermined number of times may be 100.

The above-described two processes (i.e., performing a preset number of charge and discharge cycle operations on the sample electrochemical device, and performing an intermittent charging operation on the sample electrochemical device after completing the preset number of charge and discharge cycle operations) are repeatedly performed until the total cycle number of the charge and discharge cycle operations reaches a preset number or the performance state of the sample electrochemical device is lower than a preset threshold (e.g., the ratio of the current maximum capacity of the sample electrochemical device to the rated capacity of the sample electrochemical device is lower than a preset ratio).

Wherein the total cycle number of the charge-discharge cycle operation is integral multiple of the preset times. For example, assuming that the above-described two processes are performed P times and the preset number of times is Q times for each sample electrochemical device, the total number of cycles of charge and discharge cycle operation corresponding to each sample electrochemical device is P × Q times. Further, also assuming that the above-described two processes are performed P times for each sample electrochemical device, the reference internal resistance and the lithium deposition SOC corresponding to the P groups can be acquired for each sample electrochemical device.

It should be understood that the process of obtaining the reference internal resistance and the lithium deposition SOC of the sample electrochemical device in the intermittent charging operation is similar to the process of obtaining the reference internal resistance and the lithium deposition SOC of the sample electrochemical device in the intermittent charging operation in the embodiment of fig. 1 and 3, and the corresponding description in the embodiment of fig. 1 and 4 may be referred to for the process of obtaining the reference internal resistance and the lithium deposition SOC of the sample electrochemical device in the intermittent charging operation, and will not be repeated here.

Step 814, the SOH of the sample electrochemical device is calibrated.

In the present embodiment, step 814 may be performed after each charge and discharge cycle operation of the sample electrochemical device is performed for a preset number of times. Specifically, the SOH of the sample electrochemical device may be calibrated from the perspective of the sample electrochemical device capacity. The SOH of the sample electrochemical device can also be calibrated from the battery discharge capacity point of view. Of course, the SOH of the sample electrochemical device may be calibrated from other angles. The following illustrates how the SOH of a sample electrochemical device can be calibrated by two alternative implementations.

In an alternative implementation, calibrating the SOH of the sample electrochemical device may include: the current maximum capacity of the sample electrochemical device and the rated capacity of the sample electrochemical device are obtained, and the ratio of the current maximum capacity of the sample electrochemical device to the rated capacity of the sample electrochemical device is taken as the SOH of the sample electrochemical device. Thereby enabling the SOH of the sample electrochemical device to be calibrated from the electrochemical device capacity point of view. The current maximum capacity of the sample electrochemical device is the maximum capacity that the sample electrochemical device can reach after each preset number of charge and discharge cycles of the sample electrochemical device.

In another alternative implementation, calibrating the SOH of the sample electrochemical device may include: and acquiring the current maximum discharge electric quantity of the sample electrochemical device and the maximum discharge electric quantity of the sample electrochemical device when the sample electrochemical device is not used, and taking the ratio of the current maximum discharge electric quantity of the sample electrochemical device and the maximum discharge electric quantity of the sample electrochemical device when the sample electrochemical device is not used as the SOH of the sample electrochemical device. Thereby enabling the SOH of the sample electrochemical device to be calibrated from the point of view of the amount of discharge of the electrochemical device. The current maximum discharge capacity of the sample electrochemical device refers to a maximum discharge capacity that can be reached by the sample electrochemical device after the sample electrochemical device is subjected to charge and discharge cycle operation for a preset number of times.

Step 816, establishing a mapping relation of lithium analysis SOC-reference internal resistance-SOH based on the reference internal resistance and lithium analysis SOC of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

Specifically, for each sample electrochemical device in the sample electrochemical device set, based on the reference internal resistance and the lithium analysis SOC in the multiple sets of data of the sample electrochemical device obtained in the repeated operation process and the corresponding calibrated SOH, a mapping relationship between the lithium analysis SOC and the reference internal resistance to the SOH under the corresponding operation condition of the sample electrochemical device is established. For example, a plurality of reference internal resistances, a plurality of lithium analysis SOCs and a calibrated SOH under the operating condition are correspondingly stored in a form of a two-dimensional table, and a mapping relationship as shown in table 1 is obtained.

After that, optionally, weighting processing may be performed based on the mapping relationship between the lithium analysis SOC, the reference internal resistance and the SOH under each operating condition, so as to obtain a final mapping relationship between the lithium analysis SOC, the reference internal resistance and the SOH. For example, different weights can be given to the mapping relationship between the lithium analysis SOC and the reference internal resistance to SOH under different operating conditions, and the weighted average of the mapping relationship between the lithium analysis SOC and the reference internal resistance to SOH under different operating conditions is obtained as the final mapping relationship between the lithium analysis SOC and the reference internal resistance to SOH.

It should be understood that after the final mapping relationship of lithium-separating SOC-reference internal resistance-SOH is obtained, the final mapping relationship of lithium-separating SOC-reference internal resistance-SOH may be stored for use in evaluating SOH at the actual use stage.

It should be understood that, in the embodiment of the present application, steps 810 to 816 are only used for illustrating steps that may be included in the SOH evaluation method of the electrochemical device provided in the embodiment of the present application, and the execution order between the steps is not limited. For example, steps 812 and 814 may be performed after each acquisition of one sample electrochemical device. For another example, step 814 may be executed first and then step 812 may be executed after acquiring one sample electrochemical device each time, which is not limited in this embodiment of the present application.

In the embodiment of the application, the specific electrochemical device is subjected to cycle test under different operation conditions to establish the mapping relation of the lithium analysis SOC-reference internal resistance-SOH, so that the mapping relation of the lithium analysis SOC-reference internal resistance-SOH is suitable for various operation conditions, and the SOH with higher precision can be determined by looking up a table according to the lithium analysis SOC-reference internal resistance in the subsequent use stage.

With continued reference to fig. 8, in one embodiment of the present application, the method further comprises:

step 818, obtaining the number of charge-discharge cycles of the sample electrochemical devices in the set of sample electrochemical devices before performing the intermittent charging operation.

Specifically, in one implementation, the number of cycles of one charge-discharge operation is recorded before the intermittent charging operation is performed on each sample electrochemical device, and after a preset number of charge-discharge cycle operations are performed on each sample electrochemical device. The number of cycles of the charge-discharge cycle operation per recording is an integral multiple of the preset number. For example, it is assumed that the charge and discharge cycle operation is repeated P times for each sample electrochemical device by a preset number of times. P corresponding charge-discharge cycle numbers can be obtained.

And step 820, establishing a charge-discharge cycle number-SOH mapping relation based on the charge-discharge cycle number of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

Specifically, for each sample electrochemical device in the sample electrochemical device set, a mapping relation between the charge and discharge cycle number and the SOH under the corresponding operating condition of the sample electrochemical device is established based on the obtained plurality of charge and discharge cycle numbers of the sample electrochemical device and the corresponding calibrated SOH. For example, the plurality of charge-discharge cycle numbers and the calibrated SOH under the operating condition may be correspondingly stored in a two-dimensional table, so as to obtain the mapping relationship shown in table 2.

After that, optionally, weighting processing may be performed based on the mapping relationship between the charge and discharge cycle number and the SOH under each operating condition, so as to obtain the final charge and discharge cycle number and the SOH. For example, different weights can be given to the mapping relationship between the lithium analysis SOC and the reference internal resistance to SOH under different operating conditions, and the weighted average of the mapping relationship between the lithium analysis SOC and the reference internal resistance to SOH under different operating conditions is obtained as the final mapping relationship between the lithium analysis SOC and the reference internal resistance to SOH.

In the embodiment of the application, the specific electrochemical device is subjected to cycle testing under different operation conditions, and the mapping relation of lithium analysis SOC-reference internal resistance-SOH and the mapping relation of charge and discharge cycle number-SOH are established, so that the mapping relation of lithium analysis SOC-reference internal resistance-SOH and the mapping relation of charge and discharge cycle number-SOH are both suitable for various operation conditions, and SOH can be evaluated from three dimensions of lithium analysis SOC, reference internal resistance and charge and discharge cycle number in an actual use stage, and the evaluation precision of SOH is improved.

In order to better understand the process of establishing the mapping relationship between the lithium analysis SOC and the reference internal resistance-SOH and the mapping relationship between the charge and discharge cycle number and the SOH in the embodiment of the present application, the process of obtaining the mapping relationship between the lithium analysis SOC and the reference internal resistance-SOH and the mapping relationship between the charge and discharge cycle number and the SOH under one operation condition will be described in detail with reference to fig. 9 by way of specific example. In this example, the preset number of times is 100 times, and the first SOH is 70%, where the first SOH is used to indicate a ratio of a current maximum capacity of the sample electrochemical device to a rated capacity of the sample electrochemical device when the sample electrochemical device is degraded to be unsuitable for reuse. Further, in this example, the SOH of the sample electrochemical device is calibrated from the electrochemical device capacity point of view. That is, the ratio of the current maximum capacity of the sample electrochemical device to the rated capacity of the sample electrochemical device is taken as the SOH of the sample electrochemical device. As shown in fig. 9, the method includes:

step 910, performing 100 charging and discharging operations on the sample electrochemical device.

Step 912, performing intermittent charging operation on the sample electrochemical device, and acquiring reference internal resistance and lithium precipitation SOC of the sample electrochemical device in the intermittent charging operation;

step 914, calibrating the SOH of the sample electrochemical device, and correspondingly storing the reference internal resistance, the lithium separation SOC, the current charge-discharge cycle number and the calibrated SOH of the electrochemical device;

step 916, determining that the SOH of the calibrated sample electrochemical device is less than 70%, if not, returning to steps 910-914, and if yes, executing step 918.

Step 918, establishing a mapping relation of the lithium analysis SOC-reference internal resistance-SOH under the operation condition based on the stored lithium analysis SOC and reference internal resistance of each sample electrochemical device and the calibrated SOH, and establishing a mapping relation of the charge and discharge cycle number-SOH under the operation condition based on the stored charge and discharge cycle number of each sample electrochemical device and the calibrated SOH.

It should be understood that, the specific implementation process of step 910 to step 918 may refer to corresponding steps in the embodiments shown in fig. 1 and fig. 3, and therefore, in order to avoid redundancy, detailed description is not repeated here.

An embodiment of the present application further provides an electronic device 1000, as shown in fig. 10, which includes a lithium analysis SOC analysis device 1010 and an SOH determination device 1012.

The lithium evolution SOC analysis device 1010 is configured to perform an intermittent charging operation on the electrochemical device, in which a reference internal resistance and a lithium evolution SOC of the electrochemical device are acquired. The reference internal resistance is indicative of the internal resistance when the electrochemical device is charged to the first SOC.

The SOH determining device 1012 is configured to determine the SOH of the electrochemical device based on the lithium deposition SOC, the reference internal resistance, and a pre-established mapping relationship of the lithium deposition SOC to the reference internal resistance to the SOH.

The electronic device of the embodiment of the present application may include an electrochemical device therein. Illustratively, the electronic device may be a new energy vehicle, a mobile phone, a tablet computer, or the like, which has a built-in lithium ion battery and data processing capability. The structure of the lithium deposition SOC analyzing device 1010 and the SOH determining device 1012 is not particularly limited in the embodiment of the present application as long as the corresponding functions can be realized.

In one implementation manner of the present application, the electronic device further includes an SOH correction device configured to correct the SOH after determining the SOH of the electrochemical device based on the lithium deposition SOC, the reference internal resistance, and a pre-established mapping relationship between the lithium deposition SOC and the reference internal resistance to the SOH.

In one implementation manner of the present application, the electronic device further includes an obtaining device for obtaining a current charge-discharge cycle number of the electrochemical device before the intermittent charging operation is performed on the electrochemical device. The SOH correction means is specifically configured to correct the SOH according to the current number of charge-discharge cycles.

In one implementation manner of the present application, the SOH correction apparatus is specifically configured to: determining the SOH corresponding to the current charge-discharge cycle number according to the current charge-discharge cycle number and a pre-established charge-discharge cycle number-SOH mapping relation; determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number; the SOH is corrected using the SOH allowable range.

In one implementation manner of the present application, the SOH correction apparatus is specifically configured to: determining the lower limit value of the allowable range of the SOH as the SOH corresponding to the current charge-discharge cycle number minus a first positive error; the upper limit value of the SOH allowable range is determined as SOH corresponding to the current number of charge-discharge cycles plus a first positive error.

In one implementation of the present application, the first positive error ranges from 0% to 5%.

In an implementation manner of the present application, the SOH correction apparatus is specifically configured to: if the SOH is larger than the upper limit value of the SOH allowable range, correcting the SOH to the upper limit value; if the SOH is less than the lower limit value of the allowable range of the SOH, the SOH is corrected to the lower limit value.

In one implementation of the present application, the SOH determining means 1012 determines the SOH on a periodic basis. The SOH correction means is specifically configured to correct the SOH based on the SOH determined in the previous cycle.

In one implementation of the present application, the SOH correction apparatus is specifically configured to perform at least one of the following: if the SOH is larger than the SOH determined in the previous period, correcting the SOH to be the SOH determined in the previous period; or if the SOH is less than the SOH determined for the previous cycle minus the second positive error, correcting the SOH to the SOH determined for the previous cycle minus the second positive error.

In one implementation of the present application, the second positive error ranges from 0.01% to 0.1%.

In one implementation manner of the present application, the lithium analysis SOC analysis device 1010 is specifically configured to: acquiring internal resistance and SOC of the electrochemical device during the interruption period; obtaining a first curve based on the SOC and the internal resistance during each discontinuous period, wherein the first curve represents the change of the internal resistance along with the SOC; based on the first curve, a lithium deposition SOC is determined, and based on the first curve, a reference internal resistance is determined.

In one implementation manner of the present application, the lithium analysis SOC analysis device 1010 is specifically configured to: at least one of the manner a1 and the manner a2 is performed. Mode a1 includes: differentiating the first curve to obtain a first differential curve; determining whether the first differential curve has a maximum value and a minimum value; and if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as a lithium analysis SOC. Mode a2 includes: differentiating the first curve to obtain a first differential curve; differentiating the first differential curve to obtain a second differential curve; and determining the SOC corresponding to the point where the ordinate of the second differential curve is less than zero for the first time as the lithium analysis SOC.

In one implementation of the present application, the mapping relationship between the lithium analysis SOC-reference internal resistance-SOH is pre-established by: obtaining a sample electrochemical device set; performing intermittent charging operation on the sample electrochemical devices in the sample electrochemical device set, and acquiring reference internal resistance and lithium precipitation SOC of the sample electrochemical devices in the intermittent charging operation; calibrating the SOH of the sample electrochemical device; and establishing a mapping relation of lithium analysis SOC-reference internal resistance-SOH based on the reference internal resistance and lithium analysis SOC of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

In one implementation of the present application, the pre-established charge-discharge cycle number-SOH mapping relationship is pre-established by: obtaining a number of charge-discharge cycles of a sample electrochemical device in a set of sample electrochemical devices prior to performing an intermittent charging operation on the sample electrochemical device; and establishing a charge-discharge cycle number-SOH mapping relation based on the charge-discharge cycle number of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

The electronic device in the embodiment of the present application may be used to implement the corresponding lithium analysis detection method in the foregoing method embodiments, and has the beneficial effects of the corresponding method embodiment, which are not described herein again. In addition, the description of the corresponding parts in the foregoing method embodiments can be referred to for the function implementation of each device in the electronic device of this embodiment, and is not repeated here.

As shown in fig. 11, the charging device 1100 includes a processor 1101 and a processor 1102, and the charging device 1110 may further include a charging circuit module 1103, an interface 1104, a power interface 1105, and a rectifying circuit 116. The charging circuit module 1103 is configured to perform an intermittent charging operation on a lithium ion battery (i.e., an electrochemical device); the charging circuit module 1103 may also be configured to collect parameters such as terminal voltage and charging current of the lithium ion battery, and send the parameters to the processor; interface 1104 is for electrical connection with electrochemical device 2000; the power interface 1105 is used for connecting with an external power supply; the rectifier circuit 1106 is used for rectifying an input current; the processor 1102 stores machine-executable instructions that are executable by the processor, and the processor 1101 performs the method steps of any of the above-described method embodiments when executing the machine-executable instructions.

The embodiment of the present application further provides a computer-readable storage medium, in which a computer program is stored, and when the computer program is executed by a processor, the method steps described in any of the above method embodiments are implemented.

An embodiment of the present application further provides a battery system, as shown in fig. 12, where the battery system 1200 includes a second processor 1201 and a second machine-readable storage medium 1202, and the battery system 1200 may further include a charging circuit module 1203, a lithium ion battery 1204, and a second interface 1205. The charging circuit module 1203 is configured to perform an intermittent charging operation on the lithium ion battery; the charging circuit module 1203 may also be configured to acquire parameters such as a terminal voltage and a charging current of the lithium ion battery, and send the parameters to the second processor. The second interface 1205 is used for interfacing with the external charger 1300; the external charger 1300 is for providing power; the second machine-readable storage medium 1202 stores machine-executable instructions executable by the processor to perform method steps as described in any of the above method embodiments when executed by the second processor 1201. The external charger 1300 may include a first processor 1301, a first machine-readable storage medium 1302, a first interface 1303 and a corresponding rectifying circuit, and the external charger may be a commercially available charger, and the structure of the external charger is not specifically limited in this embodiment of the present application.

The embodiment of the application also provides electronic equipment comprising the battery system.

The machine-readable storage medium may include a Random Access Memory (RAM) or a non-volatile Memory (non-volatile Memory), such as at least one disk Memory. Optionally, the memory may also be at least one memory device located remotely from the processor.

The Processor may be a general-purpose Processor, and includes a Central Processing Unit (CPU), a Network Processor (NP), and the like; the Integrated Circuit may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other Programmable logic device, a discrete Gate or transistor logic device, or a discrete hardware component.

For the electronic device/charging device/storage medium/battery system embodiment, since it is substantially similar to the method embodiment, the description is relatively simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

Claims

1. An electrochemical device health SOH assessment method comprising:

performing an intermittent charging operation on the electrochemical device, in which a reference internal resistance and a lithium evolution SOC of the electrochemical device are obtained, the reference internal resistance being indicative of an internal resistance when the electrochemical device is charged to a first SOC;

and determining the SOH of the electrochemical device based on the lithium analysis SOC, the reference internal resistance and a pre-established mapping relation of the lithium analysis SOC-reference internal resistance-SOH.

2. The method of claim 1, wherein after determining the SOH of the electrochemical device based on the lithium extraction SOC, the reference internal resistance, and a pre-established lithium extraction SOC-reference internal resistance-SOH mapping relationship, the method further comprises: and correcting the SOH.

3. The method of claim 1, wherein prior to the intermittent charging operation of the electrochemical device, the method further comprises: acquiring the current charge-discharge cycle number of the electrochemical device;

the correcting the SOH comprises: and correcting the SOH according to the current charge-discharge cycle number.

4. The method of claim 3, wherein the correcting the SOH according to the current number of charge-discharge cycles comprises:

determining the SOH corresponding to the current charge-discharge cycle number according to the current charge-discharge cycle number and a pre-established charge-discharge cycle number-SOH mapping relation;

determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number;

and correcting the SOH by using the SOH allowable range.

5. The method of claim 4, wherein the determining an SOH allowable range based on the SOH corresponding to the current charge-discharge cycle number comprises:

determining the lower limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number minus a first positive error;

and determining the upper limit value of the SOH allowable range as the SOH corresponding to the current charge-discharge cycle number plus a first positive error.

6. The method of claim 5, wherein the first positive error is in a range of 0% to 5%.

7. The method of claim 4, wherein said modifying said SOH using said SOH allowed range comprises:

if the SOH is larger than the upper limit value of the SOH allowable range, correcting the SOH to the upper limit value;

and if the SOH is smaller than the lower limit value of the SOH allowable range, correcting the SOH to be the lower limit value.

8. The method of claim 2, wherein the method is performed on a periodic basis, and wherein the correcting the SOH comprises:

and correcting the SOH based on the SOH determined in the last period.

9. The method of claim 8, wherein the correcting the SOH based on the SOH determined for the previous cycle comprises at least one of:

if the SOH is larger than the SOH determined in the previous period, correcting the SOH to be the SOH determined in the previous period; or

If the SOH is less than the SOH determined in the previous cycle minus a second positive error, the SOH is corrected to the SOH determined in the previous cycle minus the second positive error.

10. The method of claim 9, wherein the second positive error is in a range of 0.01% to 0.1%.

11. The method of claim 1, wherein the intermittent charging includes a plurality of charging periods and a plurality of intermittent periods, the performing an intermittent charging operation on the electrochemical device in which the reference internal resistance and the lithium evolution SOC of the electrochemical device are obtained includes:

obtaining an internal resistance and SOC of the electrochemical device during the interruption;

obtaining a first curve based on the SOC and the internal resistance during each interruption, the first curve representing a variation of the internal resistance with the SOC;

based on the first curve, the lithium deposition SOC is determined, and based on the first curve, the reference internal resistance is determined.

12. The method of claim 11, wherein the determining the lithium extraction SOC based on the first curve includes at least one of a mode A1 and a mode A2, wherein,

the mode a1 includes:

differentiating the first curve to obtain a first differential curve;

determining whether the first differential curve has a maximum value and a minimum value;

if the maximum value and the minimum value exist, determining the SOC corresponding to the maximum value as the lithium analysis SOC;

the mode a2 includes:

differentiating the first curve to obtain a first differential curve;

differentiating the first differential curve to obtain a second differential curve;

and determining the SOC corresponding to the point where the ordinate of the second differential curve is less than zero for the first time as the lithium analysis SOC.

13. The method of claim 4, wherein the mapping of the lithium extraction SOC-reference internal resistance-SOH is pre-established by:

obtaining a sample electrochemical device set;

performing an intermittent charging operation on sample electrochemical devices in the set of sample electrochemical devices, in which a reference internal resistance and a lithium evolution SOC of the sample electrochemical devices are obtained;

calibrating the SOH of the sample electrochemical device;

and establishing a mapping relation of the lithium analysis SOC-reference internal resistance-SOH based on the reference internal resistance and the lithium analysis SOC of each sample electrochemical device in the sample electrochemical device set and the calibrated SOH.

14. The method of claim 13, wherein the pre-established charge-discharge cycle number-SOH mapping is pre-established by:

obtaining a number of charge-discharge cycles of a sample electrochemical device of the set of sample electrochemical devices prior to performing an intermittent charging operation on the sample electrochemical device;

and establishing a charge-discharge cycle number-SOH mapping relation based on the charge-discharge cycle number and the calibrated SOH of each sample electrochemical device in the sample electrochemical device set.

15. A battery system comprising a processor, a machine-readable storage medium storing machine-executable instructions executable by the processor for detecting at least one of a pressure or a temperature of an electrochemical device, and a sensor for implementing the method of any one of claims 1-14 when the machine-executable instructions are executed by the processor.

16. An electronic device, wherein the electronic device comprises the battery system of claim 15.

17. An electronic device, comprising: a lithium analysis SOC analysis device and an SOH determination device;

the lithium evolution SOC analysis device is used for carrying out intermittent charging operation on the electrochemical device, and obtaining reference internal resistance and lithium evolution SOC of the electrochemical device in the intermittent charging operation, wherein the reference internal resistance is used for indicating the internal resistance when the electrochemical device is charged to a first SOC;

the SOH determining device is used for determining the SOH of the electrochemical device based on the lithium analysis SOC, the reference internal resistance and a pre-established mapping relation of the lithium analysis SOC to the reference internal resistance to the SOH.

18. The electronic apparatus according to claim 17, wherein the electronic apparatus further comprises SOH correction means for correcting the SOH after determining the SOH of the electrochemical device based on the lithium deposition SOC, the reference internal resistance, and a pre-established mapping relationship of lithium deposition SOC-reference internal resistance-SOH.

19. The electronic device according to claim 18, wherein the electronic device further comprises an acquisition means for acquiring a current number of charge-discharge cycles of the electrochemical device before an intermittent charging operation is performed on the electrochemical device;

the SOH correction device is specifically configured to correct the SOH according to the current charge-discharge cycle number.

20. The electronic device of claim 19, wherein the SOH correction apparatus is specifically configured to:

and correcting the SOH by using the SOH allowable range.

21. The electronic device of claim 20, wherein the SOH correction apparatus is specifically configured to:

22. The electronic device of claim 21, wherein the first positive error is in a range of 0% to 5%.

23. The electronic device of claim 20, wherein the SOH correction apparatus is specifically configured to:

24. The electronic device of claim 18, wherein the SOH determining means is specifically configured to determine the SOH on a periodic basis;

the SOH correction apparatus is specifically configured to correct the SOH based on the SOH determined in the previous cycle.

25. The electronic device of claim 24, wherein the SOH correction apparatus is specifically configured to perform at least one of:

26. The electronic device of claim 25, wherein the second positive error is in a range of 0.01% to 0.1%.

27. The electronic device of claim 17, wherein the lithium analysis SOC analysis device is specifically configured to:

determining the lithium deposition SOC based on the first curve, and determining the reference internal resistance based on the first curve.

28. The electronic device of claim 27, wherein the lithium analysis SOC analysis device is specifically configured to: performing at least one of the mode A1 and the mode A2, wherein,

the mode a1 includes:

differentiating the first curve to obtain a first differential curve;

the mode a2 includes:

differentiating the first curve to obtain a first differential curve;

29. The electronic device of claim 20, wherein the mapping of the lithium extraction SOC-reference internal resistance-SOH is pre-established by:

obtaining a sample electrochemical device set;

calibrating the SOH of the sample electrochemical device;

30. The electronic device of claim 26, wherein the pre-established charge-discharge cycle number-SOH mapping is pre-established by: