CN114883572B

CN114883572B - No negative pole piece and contain its lithium ion battery

Info

Publication number: CN114883572B
Application number: CN202210345888.7A
Authority: CN
Inventors: 请求不公布姓名; 郑军华; 汪常; 李乾坤; 赵凯
Original assignee: Svolt Energy Technology Co Ltd
Current assignee: Svolt Energy Technology Co Ltd
Priority date: 2022-03-31
Filing date: 2022-03-31
Publication date: 2024-08-02
Anticipated expiration: 2042-03-31
Also published as: CN114883572A

Abstract

The invention provides a non-negative electrode plate and a lithium ion battery comprising the same, wherein the non-negative electrode plate is a metal foil supported by a polymer, the non-negative electrode plate comprises a polymer base material provided with a through hole, an evaporation metal layer and a polymer conductive polymer layer, the evaporation metal layer is attached to the inner wall of the through hole of the polymer base material, and the polymer conductive polymer layer is arranged on the surface of the polymer base material.

Description

No negative pole piece and contain its lithium ion battery

Technical Field

The invention belongs to the technical field of lithium ion batteries, and relates to a cathode-free pole piece and a lithium ion battery comprising the same.

Background

According to measurement and calculation, the energy density of the current graphite anode lithium ion battery is up to 600Wh/L, the highest energy density of the silicon-based anode lithium ion battery can reach 800Wh/L, and along with the continuous improvement of the energy density requirement of the battery, a 1000 Wh/L lithium ion battery is needed.

Modification of the positive electrode material is an effective means for improving the energy density of the battery, and generally, the energy density of the battery is improved by 5% per year, but the innovation is very asymptotic and scattered. The innovation of the cathode material is difficult, and the cathode material breaks through greatly in 10-20 years generally. The metal negative electrode is an effective means for improving the energy density of the battery, and is beneficial to the energy density of the battery reaching 1000Wh/L, but the metal lithium can bring greater safety risk in the assembly process. In addition, larger metallic lithium blocks increase the quality of the battery and reduce the energy density of the battery. Direct contact of the metallic lithium with the electrolyte can disrupt the electrode material/electrolyte interface, causing a continual loss of active lithium.

CN114050308a discloses a structure of a lithium battery without negative electrode and a preparation method of the lithium battery without negative electrode. The cathode-free lithium battery structure comprises a cathode current collector and a cathode current collector, wherein a cathode lithium source coating is arranged outside the cathode current collector, a liquid metal coating is arranged outside the cathode current collector, and the cathode current collector are separated by a diaphragm which is mutually attached to each other.

CN113013417a discloses a cathode-free lithium metal battery, a cathode current collector and a preparation method thereof, wherein the cathode current collector comprises a cathode current collector matrix and an ion conducting layer, an electron conducting layer or an ion-electron mixed conducting layer loaded on the cathode current collector matrix.

In the non-negative electrode battery, the metal lithium directly contacts with the electrolyte to damage the electrode material/electrolyte interface, so that the active lithium is continuously lost, and the problem of poor cycle performance or poor multiplying power performance exists, so that the development of the non-negative electrode lithium ion battery with good cycle performance and good multiplying power performance is necessary.

Disclosure of Invention

The invention aims to provide a cathode-free electrode piece and a lithium ion battery comprising the cathode-free electrode piece. The scientificity of the design of the negative electrode is further improved by chemically polymerizing a layer of high-molecular conductive polymer on the surface of the metal layer, and the high-molecular conductive polymer can form a stable electrolyte interface, so that the cycling stability of the battery is improved.

In order to achieve the aim of the invention, the invention adopts the following technical scheme:

In a first aspect, the invention provides a non-negative electrode plate, which is a metal foil supported by a polymer, and comprises a polymer substrate provided with a through hole, an evaporation metal layer and a polymer conductive polymer layer, wherein the evaporation metal layer is attached to the inner wall of the through hole of the polymer substrate, and the polymer conductive polymer layer is arranged on the surface of the polymer substrate.

According to the invention, the non-negative electrode plate adopts the macromolecule supported vapor deposition composite foil, and the macromolecule layer is uniformly distributed with a plurality of through holes, so that after metal is subsequently vapor deposited, a vapor deposition metal layer is partially or completely attached to the inner wall of the through holes, and the electron transmission performance of the front and back sides of the macromolecule is penetrated. On the other hand, lithium ion transmission is facilitated, polarization is reduced, and dynamics and uniformity of metal lithium deposition are improved. And a layer of high-molecular conductive polymer is chemically polymerized on the surface of the metal foil, and the high-molecular conductive polymer has excellent electron transmission performance and stable electrolyte compatibility. In addition, the microscopic molecular structure allows lithium ions to quickly pass through the layer of high-molecular conductive polymer, so that the transmission dynamics of lithium ions is not reduced, and meanwhile, the high-molecular conductive polymer layer is beneficial to forming a stable electrolyte electrode material interface, improving the cycle performance and improving the safety of a battery.

Preferably, the material of the polymer substrate comprises polyethylene and/or polypropylene.

Preferably, the thickness of the polymer substrate is 1 to 4.5 μm, for example: 1 μm, 2 μm, 3 μm, 4 μm or 4.5 μm, etc.

Preferably, the diameter of the through-hole is 1 to 10 μm, for example: 1 μm, 2 μm, 5 μm, 8 μm or 10 μm, etc.

Preferably, the material of the evaporated metal layer includes any one or a combination of at least two of copper, gold or nickel.

Preferably, the thickness of the evaporated metal layer is 500-1000 nm, for example: 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm, etc.

Preferably, the material of the high-molecular conductive polymer layer comprises any one or a combination of at least two of polypyrrole, polythiophene and polyaniline.

The high-molecular conductive polymer layer is coated on the surface of the foil, so that in the first charging process, metal lithium is deposited on the surface of the copper foil subjected to magnetron sputtering, the deposited metal surface is coated with a layer of polypyrrole, the polypyrrole can form a uniform and stable SEI film, gas production of a battery is inhibited, the thermal stability of the SEI film is improved, and the safety performance of the battery is improved.

Preferably, the thickness of the high molecular conductive polymer layer is 50 to 500nm, for example: 50nm, 100 nm, 200nm, 300nm, 400nm, 500nm, etc.

Preferably, the thickness He of the non-negative electrode plate and the thickness Hc of the evaporated metal layer satisfy the relation of 0.5 less than or equal to HexHc less than or equal to 5, for example: 0.5, 1, 2, 3,4, 5, etc.

For example, the thickness He of the non-negative electrode sheet is 5 μm, and the thickness Hc of the vapor deposition metal layer is 0.8 μm.

Preferably, the thickness He of the non-negative electrode sheet and the aperture R of the through hole satisfy the relationship of 0.5 < HexR < 60, for example: 0.5, 1, 5, 10, 20, or 60, etc.

For example, the non-negative electrode tab thickness He is 4 μm and the aperture R of the through hole is 2 μm.

In a second aspect, the present invention provides a method for preparing the non-negative electrode sheet according to the first aspect, the method comprising the steps of:

(1) Magnetically sputtering metal on two sides of the polymer base material provided with the through holes, and attaching the metal on the inner walls of the through holes to obtain a semi-finished product;

(2) And (3) depositing a high-molecular conductive polymer on the surface of the high-molecular substrate of the semi-finished product obtained in the step (1) to obtain the cathode-free electrode plate.

Preferably, the shape of the through hole in the step (1) includes any one or a combination of at least two of square, rectangle, triangle or circle.

Preferably, the temperature of the magnetron sputtering is 23-27 ℃, for example: 23 ℃, 24 ℃, 25 ℃, 26 ℃ or 27 ℃ and the like.

Preferably, the low-pressure atmosphere of the magnetron sputtering is 0.1 to 5Pa, for example: 0.1Pa, 1Pa, 2Pa, 3Pa, 4Pa, 5Pa, etc.

Preferably, the atmosphere of the magnetron sputtering comprises argon and/or nitrogen.

Preferably, the voltage of the magnetron sputtering is 1-3 kV, for example: 1kV, 1.5kV, 2kV, 2.5kV or 3kV, etc.

Preferably, a transition metal layer of 5 to 20nm (for example, 5nm, 8nm, 10nm, 15nm, 20nm, etc.) may be added between the metal and the polymer material.

Preferably, the transition metal layer material includes any one or a combination of at least two of NiO, cr ₂O₃, cuO.

The transition metal layer can improve the binding force of the metal coating and the high polymer material.

Preferably, the method of deposition of step (2) comprises chemical deposition and/or electrochemical deposition.

Preferably, the chemical deposition method comprises the steps of preparing a solution by taking FeCl ₃ as an oxidant and Na ₂S₂O₈ as a cross-linking agent, and putting the semi-finished product obtained in the step (1) into the solution for reaction.

Preferably, the concentration of FeCl ₃ is 0.1-4 mol/L, for example: 0.1mol/L, 1mol/L, 2mol/L, 3mol/L, 4mol/L, 5mol/L, etc.

Preferably, the concentration of Na ₂S₂O₈ is 0.2-5 mol/L, for example: 0.2mol/L, 1mol/L, 2mol/L, 3mol/L, 4mol/L, 5mol/L, etc.

Preferably, the temperature of the reaction is 23-27 ℃, for example: 23 ℃, 24 ℃, 25 ℃, 26 ℃ or 27 ℃ and the like.

Preferably, the electrochemical deposition method comprises the steps of putting the polymer monomer solution obtained in the step (1) into a high-molecular conductive polymer monomer solution, and carrying out electrochemical polymerization by adopting Pt or graphite inert counter electrode.

Preferably, in the high-molecular conductive polymer monomer solution, the molar concentration of the conductive polymer monomer is 0.01-5 mol/L.

Preferably, the current of the electrochemical polymerization is 0.1 to 20A, for example: 0.1A, 1A, 5A, 10A, 15A, 20A, or the like.

Preferably, the time of the chemical polymerization is 0.2 to 120s, for example: 0.2s, 1s, 10s, 50s or 120s, etc.

In a third aspect, the present invention provides a lithium ion battery comprising a positive electrode sheet, an electrolyte and a non-negative electrode sheet according to the first aspect.

The cathode-free pole piece is applied to a lithium ion battery, lithium released from a positive electrode is deposited on the surface of a cathode-free foil, a layer of polypyrrole is polymerized on the deposited metal surface, and the polypyrrole can inhibit direct contact between metal lithium and electrolyte, so that a stable SEI film is formed, the problems of gas production, thermal runaway and the like are inhibited, and the safety performance of the battery is improved.

The thinner magnetron sputtering copper foil in the battery and the porous design in the cathode can improve the uniformity of deposition of the metallic lithium in the cathode-free foil and the charge-discharge dynamics. In addition, polypyrrole can avoid excessive irreversible capacity loss of active lithium on the surface of the anode, thereby improving the cycle performance of the battery

Compared with the prior art, the invention has the following beneficial effects:

(1) The invention adopts a design without negative electrode, the negative electrode foil is modified and functionalized, and the interface design can greatly improve the energy density of the battery and improve the safety and the cycle life of the battery. The cathode is free of electrode materials, binders and conductive agents, the quality and the volume of the battery are reduced, and the energy density is improved. The interface of the high-molecular conductive polymer is modified, the concentration of lithium salt in the electrolyte is increased, and the concentration of active lithium is increased by supplementing lithium to the positive electrode, so that the cycle life is further prolonged.

(2) The lithium ion battery provided by the invention has no negative electrode active material, binder and conductive agent, so that the quality and volume of the battery are reduced, and the battery obtains increased energy density. Compared with the pure metal copper foil of the traditional non-negative electrode battery, the non-negative electrode foil of the patent adopts the metal foil supported by the polymer, and has lighter weight.

(3) The energy density of the battery prepared from the non-negative electrode plate can reach more than 1440Wh/L, the multiplying power performance can reach more than 79%, the capacity retention rate after 1C is circulated for 1500 circles can reach more than 79%, and the battery can pass the needling experiment.

Drawings

Fig. 1 is a schematic diagram of the application of the non-negative electrode sheet of embodiment 1 of the present invention in a lithium ion battery.

Detailed Description

The technical scheme of the invention is further described by the following specific embodiments. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.

Example 1

The embodiment provides a non-negative electrode plate, which comprises the following components:

(1) The method comprises the steps of performing magnetron sputtering on the front side and the back side of a polyethylene supporting layer with the thickness of 4 mu m and provided with a through hole with the circular aperture of 5 mu m, and performing 600nm metal copper on the front side and the back side of the polyethylene supporting layer under the conditions of 25 ℃ and low-pressure environment of 2Pa and voltage of 2kV, wherein NiO with the thickness of 10nm is added between the polyethylene supporting layer and the metal copper;

(2) And (3) preparing a solution with FeCl ₃ as an oxidant, na ₂S₂O₈ as a cross-linking agent and FeCl ₃ concentration of 2mol/L and Na ₂S₂O₈ concentration of 2mol/L, and placing the semi-finished product obtained in the step (1) into the solution at 25 ℃ for chemical polymerization to obtain the non-negative electrode plate with the polypyrrole layer with the thickness of 100 nm.

The schematic diagram of the non-negative pole piece applied to the lithium ion battery is shown as the figure

Example 2

(1) The method comprises the steps of performing magnetron sputtering on the front side and the back side of a polyethylene supporting layer with the thickness of 4.5 mu m and provided with a through hole with the circular aperture of 4 mu m, and performing metal copper with the thickness of 550nm on the front side and the back side of the polyethylene supporting layer under the conditions of 25 ℃ and low-pressure environment of 2.5Pa and voltage of 2.2kV, wherein NiO with the thickness of 2nm is added between the polyethylene supporting layer and the metal copper;

(2) And (3) taking platinum as an inert counter electrode, putting the semi-finished product obtained in the step (1) into a pyrrole solution with the concentration of 2mol/L, and polymerizing for 30s under 2A to obtain the anode-free pole piece with the polypyrrole layer with the thickness of 80 nm.

Example 3

The difference between this example and example 1 is that the thickness of the through hole in step (1) is 0.5 μm, and other conditions and parameters are exactly the same as those in example 1.

Example 4

The present example differs from example 1 only in that the thickness of the through hole in step (1) is 15 μm, and other conditions and parameters are exactly the same as those in example 1.

Example 5

This example differs from example 1 only in that the other conditions and parameters for the thickness of the polypyrrole layer to be 20nm are exactly the same as in example 1.

Example 6

This example differs from example 1 only in that the other conditions and parameters for the thickness of the polypyrrole layer to be 600nm are exactly the same as in example 1.

Example 7

This example differs from example 1 only in that the thickness of the metallic copper layer is 600nm and other conditions and parameters are exactly the same as in example 1.

Example 8

The present example differs from example 1 only in that the thickness of the metallic copper layer is 1200nm and other conditions and parameters are exactly the same as those of example 1

Comparative example 1

This comparative example differs from example 1 only in that copper is not sputtered, and other conditions and parameters are exactly the same as example 1.

Comparative example 2

This comparative example differs from example 1 only in that no polypyrrole layer was provided, and other conditions and parameters were exactly the same as example 1.

Comparative example 3

This comparative example differs from example 1 only in that the polymer support layer is not provided with through holes, and other conditions and parameters are exactly the same as example 1.

Performance test: the positive electrode sheet was prepared by using NCM 811-bit positive electrode active material, PVDF as binder, SP and carbon nanotube as conductive agent, and the electrolyte was EC, EMC and DMC (volume ratio: 1:1:1) of 1.3mol/L LiPF ₆, and the negative electrode-free sheet obtained in examples 1-8 and comparative examples 1-3 was prepared into a cell, and the cell was tested for energy density of 0.5C charge and discharge, 2C discharge rate performance and cycle performance of 1500 cycles of 1C charge and discharge, and needling results, and the test results are shown in Table 1:

TABLE 1

	Energy Density (Wh/L)	Rate performance (%)	Cycle performance (%)	Needling process
					Example 1	1600	82	85	By passing through
Example 2	1520	81	84	By passing through
					Example 3	1480	80	82	By passing through
Example 4	1460	80	83	By passing through
					Example 5	1450	79	82	By passing through
Example 6	1430	80	81	By passing through
					Example 7	1440	79	80	By passing through
Example 8	1460	80	79	By passing through
					Comparative example 1	1370	74	72	Smoking device
Comparative example 2	1320	71	71	Smoke and fire

As can be seen from Table 1, according to examples 1 to 8, the energy density of the battery prepared from the non-negative electrode plate can reach more than 1440Wh/L, the multiplying power performance can reach more than 79%, and the capacity retention rate after 1500 circles of 1C can reach more than 79%, which can be achieved through needling experiments.

As can be seen from comparison between the embodiment 1 and the embodiment 3-4, in the non-negative electrode plate of the present invention, the aperture of the through hole affects the performance of the non-negative electrode plate, the aperture of the through hole is controlled to be 1-10 μm, the performance of the non-negative electrode plate is better, if the aperture is too large, the battery plate is easily fragile, and lithium deposition is uneven, and if the aperture is too small, the positive electrode and the negative electrode of the plate are not conducted, thereby affecting lithium deposition and ion transport.

As can be seen from comparison between example 1 and examples 5-6, in the non-negative electrode sheet according to the present invention, the thickness of the high polymer conductive polymer layer affects the performance of the non-negative electrode sheet, the thickness of the high polymer conductive polymer layer is controlled to be 50-500 nm, the performance of the non-negative electrode sheet is better, if the thickness of the high polymer conductive polymer layer is too large, lithium ion transmission is affected, rate performance is affected, and if the thickness of the high polymer conductive polymer layer is too small, a stable SEI film cannot be formed, thereby reducing the cycle life of the battery.

As can be seen from comparison between example 1 and examples 7-8, in the non-negative electrode sheet according to the present invention, the thickness of the evaporated metal layer affects the performance of the non-negative electrode sheet, the thickness of the evaporated metal layer is controlled to be 500-1000 nm, the performance of the non-negative electrode sheet is better, if the thickness of the evaporated metal layer is too large, the manufacturing cost and energy consumption of the electrode sheet are increased, the quality of the battery is increased, the energy density is reduced, and if the thickness of the evaporated metal layer is too small, the electron transport capacity of the electrode sheet is reduced, and the internal resistance of the battery is increased.

As can be seen from the comparison of example 1 and comparative example 1, the sputtered copper of the present invention is able to build up electron transport channels and a plateau for positive deintercalation lithium deposition. In the first charging process, the lithium released from the positive electrode can be uniformly deposited on the specially designed negative electrode plate, so that the battery has the characteristic of reversible charge and discharge.

As can be obtained by comparing the example 1 with the comparative example 2, the polypyrrole design on the surface of the non-negative electrode plate can avoid direct contact between deposited metallic lithium and electrolyte, thereby constructing a stable electrode material/electrolyte interface and improving the cycle performance and the safety performance of the battery.

By comparing the embodiment 1 with the comparative example 3, the invention arranges the through holes on the supporting layer, and the holes on the macromolecule layer can be attached with metallic copper in the magnetron sputtering process, thereby leading the front and the back of the pole piece to be conducted, and the holes are also beneficial to the transmission and the deposition of lithium ions, thereby improving the cathode dynamics of the battery.

The applicant declares that the above is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be apparent to those skilled in the art that any changes or substitutions that are easily conceivable within the technical scope of the present invention disclosed by the present invention fall within the scope of the present invention and the disclosure.

Claims

1. The lithium ion battery is characterized by comprising a positive electrode plate, electrolyte and a non-negative electrode plate, wherein the non-negative electrode plate consists of a high polymer base material provided with a through hole, a transition metal layer, an evaporation metal layer and a high polymer conductive polymer layer, the evaporation metal layer is attached to the inner wall of the through hole of the high polymer base material, the high polymer conductive polymer layer is arranged on the surface of the high polymer base material, and the transition metal layer is arranged between the high polymer base material and the evaporation metal layer;

The thickness of the macromolecule substrate is 1-4.5 mu m, the thickness of the vapor plating metal layer is 500-1000 nm, and the thickness of the macromolecule conductive polymer layer is 50-500 nm;

The material of the vapor plating metal layer comprises any one or a combination of at least two of copper, gold or nickel;

The non-negative electrode plate is prepared by adopting the following preparation method, and the preparation method comprises the following steps:

(2) Depositing a high-molecular conductive polymer on the surface of the high-molecular substrate of the semi-finished product obtained in the step (1) to obtain the non-negative electrode plate;

and (3) adding a transition metal layer between the metal and the high polymer material in the step (1).

2. The lithium-ion battery of claim 1, wherein the polymeric substrate material comprises polyethylene and/or polypropylene.

3. The lithium ion battery according to claim 1, wherein the aperture of the through-hole is 1 to 10 μm.

4. The lithium-ion battery of claim 1, wherein the material of the high molecular conductive polymer layer comprises any one or a combination of at least two of polypyrrole, polythiophene, or polyaniline.

5. The lithium-ion battery according to claim 1, wherein the thickness He of the non-negative electrode sheet and the thickness Hc of the evaporated metal layer satisfy the relationship of 0.5 +.he×hc +.5.

6. The lithium ion battery according to claim 1, wherein the thickness He of the non-negative electrode sheet and the aperture R of the through hole satisfy the relationship of 0.5 +.he x R +.60.

7. The lithium-ion battery of claim 1, wherein the shape of the through-hole of step (1) comprises any one or a combination of at least two of square, rectangular, triangular, or circular.

8. The lithium-ion battery of claim 1, wherein the temperature of the magnetron sputtering in step (1) is 23-27 ℃.

9. The lithium-ion battery of claim 1, wherein the low-pressure atmosphere for the magnetron sputtering in step (1) is 0.1 to 5Pa.

10. The lithium-ion battery of claim 1, wherein the atmosphere of magnetron sputtering of step (1) comprises argon and/or nitrogen.

11. The lithium-ion battery of claim 1, wherein the magnetron sputtering in step (1) has a voltage of 1-3 kV.

12. The lithium ion battery of claim 1, wherein a transition metal layer of 5-20 nm is further added between the metal and the polymer material in step (1).

13. The lithium-ion battery of claim 1, wherein the transition metal layer material of step (1) comprises any one or a combination of at least two of NiO, cr ₂O₃, cuO.

14. The lithium-ion battery of claim 1, wherein the method of deposition of step (2) comprises chemical deposition and/or electrochemical deposition.

15. The lithium ion battery of claim 14, wherein the chemical deposition method comprises preparing a solution with FeCl ₃ as an oxidant and Na ₂S₂O₈ as a cross-linking agent, and placing the semi-finished product obtained in the step (1) into the solution for reaction.

16. The lithium-ion battery of claim 15, wherein the concentration of FeCl ₃ is 0.1 to 4mol/L, respectively.

17. The lithium-ion battery of claim 15, wherein the Na ₂S₂O₈ has a concentration of 0.2 to 5mol/L.

18. The lithium-ion battery of claim 15, wherein the temperature of the reaction is 23-27 ℃.

19. The lithium-ion battery of claim 14, wherein the electrochemical deposition method comprises placing the polymer monomer solution obtained in step (1) into a high molecular conductive polymer monomer solution, and performing electrochemical polymerization by using Pt or graphite inert counter electrode.

20. The lithium ion battery of claim 19, wherein the molar concentration of the conductive polymer monomer in the high molecular conductive polymer monomer solution is 0.01 to 5mol/L.

21. The lithium-ion battery of claim 19, wherein the electrochemical polymerization current is between 0.1 and 20A.

22. The lithium-ion battery of claim 19, wherein the electrochemical polymerization time is from 0.2 to 120 seconds.