JP2003200739A - Accumulating electricity device and its usage - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an accumulating electricity device capable of improving regeneration capability at the time of deceleration in hybrid vehicles and minimizing the size and reducing the cost, and its method for use. <P>SOLUTION: The constitution consists of the circuit connecting in parallel with at least one secondary battery 2 (e.g. a lithium secondary battery) using material containing at least one kind selected from non-graphite carbon material (e.g. hard carbon) and amorphous oxide (e.g. silicon dioxide) for negative pole active material, and at least one capacitor 3 (e.g. an electric double layer capacitor). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power storage device used in, for example, a hybrid vehicle, which can be reduced in size and cost, and can improve regenerative ability during deceleration when mounted on a vehicle. And a method of using such a power storage device.

[0002]

2. Description of the Related Art A hybrid vehicle using an electric motor as an auxiliary drive source for assisting the output of an engine has been studied. In such a hybrid vehicle, a secondary battery has hitherto been used as a power source for driving the auxiliary drive motor. Is used.

On the other hand, a power storage device in which a capacitor and a battery are connected in parallel, which can discharge a large output in a short time, is considered as a power source for a hybrid vehicle in order to generate an instantaneous high output such as engine start or rapid acceleration. There is. For example,
Japanese Patent Application Laid-Open No. 8-193564 proposes to reduce the load on the battery due to the lock current at the time of starting the engine, thereby reducing the size of the system and extending the life of the battery.

Recently, in order to compensate for the low temperature output of the battery, a power storage device in which a secondary battery and a capacitor are connected in parallel has been studied as a power source for a hybrid vehicle. For example, Japanese Patent Application Laid-Open No. 10-294135 proposes a hybrid element that uses a combination of a capacitor and a battery as a power source having good pulse discharge characteristics at low temperatures. In a secondary battery involving a chemical reaction, the internal resistance increases as the temperature of the secondary battery decreases, and the dischargeable / chargeable power decreases. If the performance of a vehicle is designed based on the performance of the secondary battery at room temperature, the battery performance at low temperature will decrease, and the expected vehicle performance cannot be exhibited at low temperature.
In addition, if the performance of a vehicle is designed based on the performance of the secondary battery at low temperatures, it becomes necessary to mount a large number of secondary batteries on the vehicle. Will end up. Therefore, in actuality, the vehicle performance at the time of low temperature is sacrificed to some extent.

On the other hand, since the output characteristics of the capacitor hardly change with changes in temperature, it is possible to use a capacitor as a power storage device in which the output at low temperature is supplemented by connecting the secondary battery and the capacitor in parallel. For example, it is predicted that a compact and low-cost power storage device can be obtained as compared with a device that includes a single secondary battery.

[0006]

However, when a secondary battery using graphite as a negative electrode active material is used as a power source for a hybrid vehicle as a secondary battery connected in parallel with a capacitor, it is regenerated during deceleration. When the power storage device is charged, the difference between the upper limit voltage and the open circuit voltage is too small, so there is no significant improvement in deceleration regeneration, and there is the problem that the advantage of connecting in parallel with the capacitor can hardly be expected. In particular, at low temperatures where the performance of the battery is extremely reduced, the capacitor plays a large role during deceleration regeneration, and the regenerative input is extremely low in the secondary battery using graphite with a small difference between the upper limit voltage and the open circuit voltage as the negative electrode active material. However, there has been a problem in that such a problem is solved in a power storage device including a secondary battery using graphite and a capacitor.

[0007]

An object of the present invention is to solve the above-mentioned problems in the conventional power storage device, and it is possible to improve the regenerative ability at the time of deceleration in a hybrid vehicle, and to make it compact and low in cost. An object of the present invention is to provide a power storage device capable of achieving the above and a method of using such a power storage device.

[0008]

The power storage device according to the present invention is provided with at least one secondary battery using, as a negative electrode active material, a material containing at least one selected from a non-graphitic carbon material and an amorphous oxide. A battery and at least one capacitor are connected in parallel, and such a structure of the power storage device is a means for solving the above-mentioned conventional problems.

As a preferred embodiment of the electricity storage device according to the present invention, the negative electrode active material of the secondary battery is composed only of non-graphitic carbon material, the non-graphitic carbon material is hard carbon, The secondary battery is a lithium secondary battery, and the capacitor is an electric double layer capacitor.

In use of the power storage device according to the present invention, when the vehicle is decelerated, a generator is driven from the wheels to charge the battery to store regenerative energy. As a preferred mode of using the power storage device, the vehicle is It is characterized in that the hybrid vehicle is equipped with an electric motor together with an engine as a driving source for traveling.

[0011]

Most of the lithium secondary batteries currently on the market use graphite as the negative electrode active material. In a lithium secondary battery using such graphite, as shown by the curve b in FIG. In addition, since the difference between the upper limit voltage and the open circuit voltage is too small, when using it as a power source for a hybrid vehicle,
The amount of energy that can be regenerated during deceleration decreases. On the other hand, in a lithium secondary battery using a non-graphitic carbon material such as hard carbon or an amorphous oxide such as silicon oxide as the negative electrode active material, the curve a in FIG.
Alternatively, as shown by the curve c, since the change in the open circuit voltage with respect to the state of charge is large and the difference between the upper limit voltage for use and the open circuit voltage is large, the amount of energy that can be regenerated during vehicle deceleration is the lithium secondary battery using graphite as the negative electrode active material. It is larger than a battery.

[0012] Such an effect becomes more remarkable when a battery and a capacitor are connected in parallel and used as a power source of a hybrid vehicle. Therefore, it is necessary to use a battery that has a large difference between the maximum operating voltage and the open circuit voltage, such as a lithium secondary battery that uses hard carbon or silicon oxide as the negative electrode active material, for the battery that is connected in parallel with the capacitor. Becomes

In the present invention, the secondary battery having a large difference between the upper limit voltage and the open circuit voltage, that is, the material containing at least one selected from the above non-graphitic carbon materials and amorphous oxides is used as the negative electrode active material. By connecting at least one secondary battery and at least one capacitor used in the material in parallel, the capacitor excellent in low-temperature characteristics assists input and output, thus improving the deceleration regeneration capacity of the vehicle, The power storage device can be made compact and the cost can be reduced.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An electricity storage device according to the present invention includes at least one secondary battery using as a negative electrode active material a material containing at least one selected from non-graphitic carbon materials and amorphous oxides. One capacitor is connected in parallel, and by connecting the secondary battery and the capacitor in parallel, the capacitor with good low-temperature characteristics assists the input and output, and the regenerative energy during vehicle deceleration increases. The effect is obtained. Here, the secondary battery is a positive electrode, a negative electrode,
Each electrode is composed of an electrolytic solution and a separator, and each electrode has a form in which an active material is applied to a metal foil for current collection. In the present invention, it is essential to use a material containing at least one selected from non-graphitic carbon materials and amorphous oxides as the negative electrode active material. That is, since the secondary battery using the non-graphitic carbon material or the amorphous oxide as the negative electrode active material has a large difference between the upper limit voltage and the open circuit voltage,
The input that can be regenerated is large, and the advantage of using it in parallel with the capacitor can be maximized.

Here, the non-graphitic carbon material means a carbon material other than the graphitic carbon material, and specifically,
Carbonaceous materials (soft carbon, hard carbon) and low temperature fired carbon can be used. The amorphous oxide is an oxide of a metal such as nickel, cobalt, titanium, silicon or tin, and means an amorphous metal oxide.
These non-graphitic carbon materials and non-crystalline oxides can be used alone or as a mixture, and their composite oxides can also be used. In any case, the effect is exhibited.

Further, in the present invention, it is necessary to use at least one capacitor. Here, the capacitor means a device having an electric capacity, and specifically, an aluminum electrolytic capacitor, a tantalum electrolytic capacitor, an organic semiconductor solid electrolytic capacitor, an electric double layer capacitor or the like can be used. A capacitor is like a secondary battery,
Since there is no chemical reaction during charging / discharging, there is little decrease in output at low temperatures. Therefore, by connecting the capacitor in parallel with the secondary battery to supplement the output at low temperature with the capacitor, the size and cost of the secondary battery can be reduced as compared with the case of the secondary battery alone. At least one capacitor is required to achieve the object of the present invention, and the number of capacitors to be used can be appropriately increased according to the demand.

In a preferred form of the electricity storage device according to the present invention, a secondary battery using only a non-graphitic carbon material as the negative electrode active material can be used. A secondary battery using a non-graphitic carbon material as the negative electrode active material has a large difference between the upper limit voltage and the open circuit voltage, so the regenerable input becomes large,
It is possible to maximize the advantages of the device that is used in parallel with the capacitor.

In another preferred embodiment of the electricity storage device according to the present invention, a secondary battery using hard carbon as a non-graphitic carbon material as a negative electrode active material can be used.
Here, hard carbon means non-graphitizable carbon,
It is a carbonaceous material having a structure close to an amorphous structure represented by glassy carbon, and does not become graphite even when heat-treated at a high temperature (3000 ° C. or higher). Similarly, a secondary battery using hard carbon as the negative electrode active material is
Since the difference between the upper limit voltage and the open circuit voltage is large, the regenerable input is large, and the merit of the device used in parallel with the capacitor is maximized.

In still another preferred embodiment of the power storage device according to the present invention, it is desirable to use a lithium secondary battery as the secondary battery. That is, as a secondary battery using a non-graphitic carbon material or a non-crystalline oxide such as a metal oxide as a negative electrode active material, there is a lithium secondary battery or a magnesium secondary battery. The battery is the lightest in weight and has the largest output density as compared with other secondary batteries, and is advantageous from the viewpoint of weight reduction and high output when mounted on, for example, an automobile.

Further, in the electricity storage device according to another preferred embodiment of the present invention, it is desirable to apply an electric double layer capacitor as the capacitor. Electric double-layer capacitors, compared to other capacitors, such as electrolytic capacitors,
It has a storage capacity of 10 to 100 times or more and has excellent output characteristics. For example, when obtaining an equivalent output, an electric double layer capacitor requires only 1 kg, but an electrolytic capacitor requires 100 kg. become. Therefore, when it is mounted on, for example, an automobile, it is advantageous from the viewpoint of weight saving and space saving.

As a method of using the above electricity storage device according to the present invention, regenerative energy can be stored by charging the electricity storage device by driving a generator from the wheels during vehicle deceleration. By using the power storage device including a secondary battery having a large difference between the upper limit voltage and the open-circuit voltage and a capacitor for charging, a larger number of power storage devices than the power storage device using the secondary battery having a small difference between the upper-limit voltage and the open circuit voltage is used. Energy can be charged and deceleration regenerative energy can be stored efficiently. Further, at low temperature when the output of the secondary battery decreases, the capacitor connected in parallel to the secondary battery compensates for the output decrease of the secondary battery, and becomes a high-performance, compact power storage device. This is advantageous in terms of high output and space saving.

As a preferred mode of using the power storage device according to the present invention, it is preferable that the vehicle is a hybrid vehicle equipped with an electric motor in addition to an engine as a driving source for traveling. By making the vehicle a hybrid vehicle, the power storage device can assist the engine only for a short time when the vehicle starts or accelerates, and can be driven by the engine during normal running, for example, without the engine, Compared to an electric vehicle that runs only on a power storage device,
More compact and less expensive.

A hybrid vehicle is a vehicle that has both an engine and an electric motor as a drive source for traveling the vehicle. Specifically, a series hybrid vehicle in which the power storage device is a vehicle drive motor or a vehicle auxiliary device and has no power source other than the vehicle drive motor, and the power storage device is a vehicle drive motor or a vehicle auxiliary device. , There are parallel hybrid vehicles that have a power source other than the vehicle drive motor. The power storage device according to the present invention can be effectively used in both a series hybrid vehicle and a parallel hybrid vehicle, and it may be conveniently examined which one is used according to a request.

[0024]

EXAMPLES The present invention will be described more specifically below based on examples. (Embodiment 1) FIG. 2 shows a power storage device according to the present invention. In the power storage device 1, a secondary battery 2 and two capacitors 3 and 3 connected in series are connected in parallel. It consists of a circuit. Here, the secondary battery 2 has a Coulomb capacity of 3.5 A using hard carbon as the negative electrode active material.
In addition to using the lithium secondary battery of h, an electric double layer capacitor having an electrostatic capacity of 200 F is used as the capacitor 3, and as shown in FIG. 2, two capacitors 3 and 3 are connected in series and A lithium secondary battery 2 is connected in parallel.

The performance at −30 ° C. when the power storage device 1 having the above circuit structure was used as a power source for a hybrid vehicle was investigated, and the same specifications as the above lithium secondary battery using hard carbon as the negative electrode active material were investigated. Compared with the case of using it alone. The result is shown in FIG. In FIG. 3, the horizontal axis represents the state of charge of the battery and the vertical axis represents the regenerable input. Further, in the figure, a is an embodiment of the present invention in which the lithium secondary battery 3 and two electric double layer capacitors 3 and 3 are connected in parallel, and b is a comparison using only the lithium secondary battery 3 alone. Here is an example:

As is clear from the results shown in FIG.
It was confirmed that the regenerative input is remarkably increased by connecting the capacitor 3 in parallel with the secondary battery 2 at a low temperature of 30 ° C.

Example 2 In the case of using a lithium secondary battery using silicon oxide, which is an amorphous oxide, as the negative electrode active material as the secondary battery in the electricity storage device 1 shown in FIG. Similarly, the performance at −30 ° C. was investigated, and in the case of the above-mentioned Example 1 in which a lithium secondary battery using hard carbon as the negative electrode active material was used, and a lithium secondary battery using graphite as the negative electrode active material was used. It was compared with the performance when it was done. The result is shown in FIG. In addition, in FIG. 4, the vertical axis represents the value obtained by subtracting the regenerable input in the case of only the secondary battery alone from the regenerable input when the respective secondary batteries and capacitors are connected in parallel, that is, the electric double layer capacitor is also used. The increase in performance due to doing is shown. Further, in FIG. 4, a shows the case of Example 1 in which hard carbon is used as the negative electrode active material, b shows the case of using silicon oxide as the negative electrode active material, and c shows the case of the comparative example using graphite. ing.

In FIG. 4, the increase in the regenerative input due to the parallelization of the secondary battery and the capacitor is, for example, when the state of charge is 3
When compared with the increase at 0%, it is 0.035 kW when graphite is used as the negative electrode active material, while 0.085 kW when hard carbon is used,
In the case of silicon oxide, it was 0.072 kW, and the effect of two times or more was recognized. This indicates that by using hard carbon, it is possible to maximize the effect of the capacitors connected in parallel.

(Embodiment 3) In the electricity storage device 1 shown in FIG. 2, a lithium secondary battery using hard carbon as a negative electrode active material is used as the secondary battery 2, and the secondary battery 2 is connected in parallel with the lithium secondary battery 2. When the capacitance of the connected electric double layer capacitors 3 and 3 is changed to 100F and 50F-
Similarly, the performance at 30 ° C. was investigated, and 200 of Example 1 was investigated.
Compared with the case of F. The result is shown in FIG. At this time, the vertical axis represents a value obtained by subtracting the regenerable input in the case of the secondary battery alone from the regenerable input when the secondary battery and the capacitor are connected in parallel, as in FIG. As a result, it was confirmed that the larger the capacity of the capacitor to be connected, the more the increase in the regenerable input.

(Embodiment 5) FIG. 6 is a block diagram for explaining a mode in which the power storage device according to the present invention is applied to a parallel hybrid vehicle. In this figure, a thick solid line indicates a mechanical force transmission path, Thick broken lines indicate power lines. The thin solid line indicates the control line.

The power train of this vehicle includes a generator motor 11, an engine 12, a clutch 13, and a drive motor 1.
4, a continuously variable transmission 15, a differential device 16 and drive wheels 17. Output shaft of generator motor 11, engine 1
The output shaft of 2 and the input shaft of the clutch 13 are connected to each other, and the output shaft of the clutch 13, the output shaft of the drive motor 14 and the input shaft of the continuously variable transmission 15 are connected to each other.

When the clutch 13 is engaged, the engine 12 and the drive motor 14 serve as a vehicle propulsion source, and the clutch 13
When released, only the drive motor 14 serves as a vehicle propulsion source. The driving force of the engine 12 and / or the drive motor 14 is transmitted to the drive wheels 17 via the continuously variable transmission 15 and the differential device 16.

The generator motor 11 and the drive motor 14 are AC machines such as a three-phase synchronous motor or a three-phase induction motor. The generator motor 11 is mainly used for engine starting and power generation, and the drive motor 14 is mainly for propulsion and braking of the vehicle. Used for. Further, when the clutch 13 is engaged, the generator motor 11 can be used for propulsion and braking of the vehicle, and the drive motor 14 can be used for engine start and power generation.

The clutch 13 is a powder clutch,
The transmission torque can be adjusted. The clutch 13 may be a dry single plate clutch or a wet multi-plate clutch. The continuously variable transmission 15 is a continuously variable transmission such as a belt type or a toroidal type, and can continuously adjust the gear ratio.

The generator motor 11 and the drive motor 14 are driven by inverters 18 and 19, respectively. The inverters 18 and 19 are connected to the power storage device 1 according to the present invention via a common DC link 20, and convert the DC discharge power of the power storage device 1 into AC power to generate the motor 1.
1. The AC power generated by the generator motor 11 and the drive motor 14 is converted into DC power while being supplied to the drive motor 14 to charge the power storage device 1. Inverter 1
Since 8 and 19 are connected to each other via the DC link 20, the electric power generated by the motor during the regenerative operation can be directly supplied to the motor during the power running operation without passing through the power storage device 1.

The electric power of the power storage device 1 is connected to the DC / DC converter 22 via the DC link 20, and the auxiliary device 2 of the vehicle is connected.
3 is supplied with electric power. As shown in FIG. 2, the power storage device 1 is a power source in which a secondary battery 2 and a capacitor 3 are connected in parallel. The controller 24 controls the rotation speed and torque of the engine 12, the gear ratio of the continuously variable transmission 15, the charging / discharging of the power storage device 1, and the like.

[0037]

As described above, the electricity storage device according to the present invention comprises at least one selected from a non-graphitic carbon material such as hard carbon and an amorphous oxide such as silicon oxide. At least one secondary battery using a material containing a negative electrode active material and at least one capacitor connected in parallel, the open-circuit voltage changes greatly with respect to the state of charge, and the upper limit voltage and the open-circuit voltage are used. Since a secondary battery with a large difference is used, when using it as a power source for a hybrid vehicle, use a lithium secondary battery that uses graphite as the negative electrode active material because of the amount of energy that can be regenerated during vehicle deceleration. It will be larger than in the case of doing so, it will be possible to improve the fuel efficiency performance of the vehicle and make the battery compact and cost reduction in the hybrid vehicle. Cormorants extremely excellent effect is brought about.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the state of charge and the open circuit voltage of lithium secondary batteries using various negative electrode active material materials.

FIG. 2 is a diagram showing a circuit configuration including a secondary battery and a capacitor in a power storage device according to the present invention.

FIG. 3 is a graph showing the performance of a power storage device according to the present invention in comparison with a device including only a secondary battery.

FIG. 4 is a graph showing an influence of a negative electrode active material of a secondary battery on a performance improvement range by paralleling with a capacitor.

FIG. 5 is a graph showing the influence of the capacitance of the capacitor on the range of performance improvement due to parallelization with the capacitor.

FIG. 6 is a block diagram showing an example in which the power storage device according to the present invention is applied to a parallel hybrid vehicle.

[Explanation of symbols]

1 power storage device 2 Secondary battery 3 capacitors 11 Generator motor 12 engine 14 Drive motor (electric motor)

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01M 10/40 B60K 6/04 ZHV (72) Inventor Hitoshi Ito 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Takaaki Abe 2 Takaracho, Kanagawa-ku, Kanagawa Prefecture Kanagawa F-Term (Reference) 5H029 AJ00 AL02 AL06 DJ18 HJ12 5H050 AA00 BA17 CB07 FA20 5H115 PA08 PA15 PC06 PG04 PI16 PO06 PO07 PO17 PU27 PV02 PV09 QE10 QI04 SE06 TI01 TI05

Claims (7)

[Claims] 1. At least one secondary battery using a material containing at least one selected from a non-graphitic carbon material and an amorphous oxide as a negative electrode active material, and at least one capacitor in parallel. A power storage device characterized by being connected. 2. The power storage device according to claim 1, wherein the negative electrode active material material of the secondary battery is composed only of a non-graphitic carbon material. 3. The power storage device according to claim 1, wherein the non-graphitic carbon material is hard carbon. 4. The power storage device according to claim 1, wherein the secondary battery is a lithium secondary battery. 5. The power storage device according to claim 1, wherein the capacitor is an electric double layer capacitor. 6. The use of the power storage device according to claim 1, wherein a generator is driven from a wheel to charge the battery when the vehicle decelerates to store regenerative energy. 7. The use of a power storage device according to claim 6, wherein the vehicle is a hybrid vehicle equipped with an electric motor together with an engine as a driving source for traveling.