JP5355429B2 - Positive electrode for power storage device, manufacturing method thereof, and power storage device cell - Google Patents

Description

  The present invention relates to a configuration of a positive electrode for a power storage device used in a power storage device cell incorporating a configuration of a lithium ion capacitor and a lithium ion battery, and a manufacturing method thereof.

  Examples of the power storage device cell include an electric double layer capacitor, a lithium ion battery, and a lithium ion capacitor. Capacitors are provided with polarizable electrodes (positive and negative electrodes) facing each other with a separator interposed therebetween, and use the capacitance of the electric double layer formed on the surface of the polarizable electrode in the electrolyte It is. Here, the capacitor is also referred to as an electric double layer capacitor, a super capacitor, an electrochemical capacitor, or the like, and a lithium ion capacitor described below is also included in this capacitor.

  The lithium ion battery is characterized in that lithium can be stably charged and stored in the carbon negative electrode. An oxide such as cobalt, nickel, or manganese is used for the positive electrode.

  The electric double layer capacitor does not have the instantaneous power as much as that of the aluminum electrolytic capacitor, but has an advantage that the output density is large and charging / discharging can be performed in a short time. On the other hand, the lithium ion battery is a power storage device having an overwhelming energy density (ie, sustainability) among the power storage devices. If a power storage device cell that has both the instantaneous power of a capacitor and the sustainability of a lithium battery can be realized, it can be used for various applications such as hybrid vehicles and various types of brake regeneration.

  In addition, lithium ion capacitors have been developed as new capacitors. This lithium ion capacitor is obtained by doping lithium ions into the negative electrode of an electric double layer capacitor, and has a characteristic that an upper limit voltage higher than that of the electric double layer capacitor can be obtained but the lower limit voltage cannot be reduced to 0V. Hereinafter, the lithium ion capacitor is referred to as a capacitor for the sake of simplicity.

  As a power storage device cell incorporating a structure of a capacitor and a lithium ion battery, there is one disclosed by the same applicant as the present invention (see, for example, Patent Document 1). This patent document 1 can realize an ideal power storage device that combines the instantaneous power of an electric double layer capacitor and the sustainability of a lithium ion battery.

Japanese Patent Laying-Open No. 2009-141181 (see FIGS. 1 and 12)

However, the prior art has the following problems.
The conventional power storage device cell has a problem that deterioration of the battery positive electrode increases when rapid charge / discharge is repeated by utilizing the instantaneous force of the capacitor. As a result of investigating and investigating the cause, it was found that deterioration was promoted by the following two factors.
(Factor 1) When the battery is charged, the capacitor generates a large amount of heat. When the battery is charged, the temperature of the battery positive electrode, which easily deteriorates, is increased to accelerate the side reaction and increase the deterioration.
(Factor 2) On the contrary, there is a large heat absorption of the capacitor at the time of discharging, and a large temperature difference is locally generated inside the positive electrode at the time of charging / discharging, thereby causing physical changes such as expansion / contraction of the battery positive electrode. .

  The present invention has been made in order to solve the above-mentioned problems, and is a battery positive electrode that occurs when rapid charge / discharge is repeated by mitigating local temperature rise and local temperature change during charging. An object of the present invention is to obtain a power storage device positive electrode capable of suppressing deterioration of the battery, a method for manufacturing the same, and a power storage device cell.

The power storage device positive electrode according to the present invention includes a positive electrode current collector foil and a positive electrode current collector foil, on which one side of the positive electrode current collector foil is formed with a capacitor positive electrode layer including activated carbon particles that generate heat during charge and absorb heat during discharge. A positive electrode for a power storage device comprising a battery positive electrode layer formed with a battery positive electrode layer containing particles of a lithium-containing metal compound that absorbs heat during charge and generates heat during discharge. The foil has a thickness of 7 μm or more and less than 15 μm, and the positive electrode current collector foil sandwiched between the capacitor positive electrode layer and the battery positive electrode layer follows the shape of the particles contained in the capacitor positive electrode layer and the battery positive electrode layer. and those that have undulating.

In addition, the method for producing a positive electrode for a power storage device according to the present invention includes a capacitor positive electrode layer having a capacitor positive electrode layer including activated carbon particles that generate heat during charge and absorb heat during discharge on one surface of the positive electrode current collector foil. A battery positive electrode layer on which the battery positive electrode layer containing particles of a lithium-containing metal compound that absorbs heat during charge and generates heat during discharge is formed on the other surface of the positive electrode current collector foil. The positive electrode current collector foil sandwiched between the capacitor positive electrode layer and the battery positive electrode layer has undulations along the shape of the particles contained in the capacitor positive electrode layer and the battery positive electrode layer. A method for producing a positive electrode for a power storage device, comprising the step of forming a undulation of a positive electrode current collector foil by a hot roll press.

Furthermore, the power storage device cell according to the present invention includes a capacitor positive electrode in which a capacitor positive electrode layer including activated carbon particles that generate heat during charge and absorb heat during discharge is formed on one surface of the positive electrode current collector foil, and a positive electrode current collector foil. A battery positive electrode layer on which the battery positive electrode layer containing particles of a lithium-containing metal compound that absorbs heat during charging and generates heat during discharge is formed on the other surface of the electric foil. The positive electrode current collector foil that is 7 μm or more and less than 15 μm and is sandwiched between the capacitor positive electrode layer and the battery positive electrode layer has undulations along the shape of the particles contained in the capacitor positive electrode layer and the battery positive electrode layer Common to the positive electrode for a power storage device, and a common negative electrode having a negative electrode layer formed on both sides of the negative electrode current collector foil and having a through-hole penetrating only the current collector foil or the entire negative electrode. negative The poles are alternately stacked or wound through separators.

  According to the present invention, the positive electrode current collector foil is thinned to provide undulations to promote heat transfer between the activated carbon particles on the front and back surfaces and the particles of the thium-containing metal compound, and the heat absorption and heat generation during charging and discharging are front and back. The battery positive electrode, which is opposite to the capacitor positive electrode, is placed behind the positive electrode current collector foil to reduce local temperature rise and local temperature change during charging, and occurs when repeated rapid charge / discharge It is possible to obtain a power storage device positive electrode capable of suppressing deterioration of the battery positive electrode, a manufacturing method thereof, and a power storage device cell.

It is a cross-sectional schematic diagram of the electric power storage device cell in Embodiment 1 of this invention. It is a cross-sectional enlarged schematic diagram of the positive electrode for electric power storage devices in Embodiment 1 of this invention. A charge-discharge curve of the lithium battery using the lithium-containing cobalt oxide (LiCoO ₂₎ positive electrode in the first embodiment of the present invention, is a graph showing the relationship between heat absorption, heat generation. It is explanatory drawing regarding the manufacturing method which makes the undulation of the positive electrode current collection foil in Embodiment 1 of this invention. It is a characteristic view at the time of quick charge of the electric power storage device cell in Embodiment 1 of this invention. It is a characteristic view at the time of rapid discharge of the electric power storage device cell in Embodiment 1 of this invention. It is a plane block diagram of the power storage device cell for performance tests in Embodiment 1 of the present invention. It is a cross-sectional schematic diagram of the electric power storage device cell in Embodiment 2 of this invention. It is a cross-sectional schematic diagram of the electric power storage device cell in Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a schematic cross-sectional view of a power storage device cell according to Embodiment 1 of the present invention. The power storage device cell in the first embodiment includes a hybrid positive electrode 10, two common negative electrodes 20, a first separator 31, and a second separator 32.

  The hybrid positive electrode 10 is configured by forming a capacitor positive electrode layer 13 including activated carbon particles 12 and a lithium battery positive electrode layer 15 including lithium-containing metal compound particles 14 on both sides of the positive electrode current collector foil 11. In addition, the two common negative electrodes 20 are formed with a capacitor negative electrode layer 22 and a lithium battery negative electrode layer 23 coated with carbon particles on the front and back surfaces of the negative electrode current collector foil 21 and then through holes (not shown). The electrolyte solution is communicated.

  The capacitor positive electrode layer 13 and the capacitor negative electrode layer 22 are opposed to each other via the first separator 31 to constitute a capacitor unit. Further, the lithium battery battery positive electrode layer 15 and the lithium battery negative electrode layer 23 are opposed to each other via the second separator 32 to constitute a lithium battery portion.

  By stacking the strip-like hybrid positive electrode 10, the common negative electrode 20, the first separator 31, and the second separator 32 alternately, a stacked power storage device is configured. Further, by winding together the roll-shaped hybrid positive electrode 10, the common negative electrode 20, the first separator 31, and the second separator 32, a wound type or flat wound type electricity storage device is configured.

As the electrolytic solution, for example, an electrolytic solution in which LiPF ₆ that is an electrolyte is contained in an organic solvent can be used, which is shared by the capacitor unit and the lithium battery unit. As the organic solvent, for example, propylene carbonate (PC), ethylene carbide (EC), or diethyl carbonate (DEC) can be used.

  As the positive electrode current collector foil 11, it is desirable to use an aluminum foil having a thickness of 7 μm or more and 15 μm or less. The negative electrode current collector foil 21 includes a capacitor negative electrode layer 22 and a lithium battery negative electrode in which carbon particles such as graphite and hard carbon are coated on the front and back surfaces of a copper foil having a thickness of about 10 μm to 20 μm. After forming the layer 23, the through hole 24 can be physically opened by using a sharpened tip such as Kenzan.

  Further, as another form, using a punching metal copper foil or an expanded metal copper foil having a thickness of about 10 μm to 20 μm with a through-hole 24 formed in advance, the capacitor negative electrode layer 22 and lithium The negative electrode current collector foil 21 in which the battery negative electrode layer 23 is formed can be used.

  The first separator 31 and the second separator 32 are, for example, porous having a thickness of about 10 to 50 μm, a porosity (porosity) of about 60 to 80% by volume, and an average pore diameter of about several to several tens of μm. Cellulose, polyethylene, polypropylene and the like can be used.

  As the activated carbon particles 12 of the capacitor positive electrode layer 13, it is preferable to use particles having an average particle diameter of about 1 to 10 μm, which are activated by steam or alkali using phenol resin, petroleum pitch, petroleum coke, coconut shell, or the like as a raw material. desirable.

As the lithium-containing metal compound particles 14 of the lithium battery positive electrode layer 15, lithium cobalt oxide (LiCoO ₂ ) is desirable because of the large amount of heat absorbed during charging and large amount of heat generated during discharging. Other lithium-containing metal compound particles 14 may be lithium cobalt oxide containing lithium nickel oxide (LiNiO ₂ ) or lithium manganese oxide (LiMn ₂ O ₄ ), which absorbs heat during charge and generates heat during discharge. It may be a multi-component system such as a ternary system or a quaternary system.

  The average particle size of the lithium-containing metal compound particles 14 is preferably about 2 to 10 μm. In particular, the average particle diameter of the lithium-containing metal compound particles 14 is desirably close to the average particle diameter of the activated carbon particles 12 of the capacitor positive electrode layer 13.

  As the material for the capacitor negative electrode layer 22 and the lithium battery negative electrode layer 23, carbon fine particles such as graphite, hard carbon, amorphous carbon, mesocarbon microbead graphite, etc. used in general lithium ion batteries are used. it can. Further, the average particle diameter is desirably about 1 to 20 μm.

Next, details of endothermic heat generation and hybrid positive electrode structure due to charging / discharging of lithium-containing cobalt-based oxide particles 14 of the lithium battery positive electrode layer 15 and activated carbon particles 12 of the capacitor positive electrode layer 13 in the first embodiment. explain. FIG. 2 is a schematic enlarged cross-sectional view of the positive electrode for a power storage device according to Embodiment 1 of the present invention. FIG. 3 is a graph showing the relationship between the charge / discharge curve of the lithium battery using the lithium-containing cobalt oxide (LiCoO ₂ ) positive electrode according to Embodiment 1 of the present invention and the endothermic / heat generation.

As is apparent from FIG. 3, the lithium cobalt oxide (LiCoO ₂ ) positive electrode has a large endotherm during the initial charge, that is, while the voltage rises from about 2.9 V to about 3.8 V, and the end of discharge, that is, the voltage Generates a large amount of heat while the voltage drops from 3.8V to about 2.8V. These endothermic amounts and calorific values are greater than Joule heat, that is, calorific values proportional to the square of internal resistance and current. Therefore, due to the influence of this lithium cobalt oxide (LiCoO ₂ ) positive electrode, the temperature of the lithium battery part decreases during charging and increases during discharging.

This phenomenon is widely known and has been found to be an endothermic amount and an exothermic amount of entropy change based on crystal change of lithium cobalt oxide (LiCoO ₂ ). In addition to lithium cobalt oxide (LiCoO ₂ ), the endothermic amount and the calorific value of the ternary lithium-containing oxide of Co, Mn, and Ni are generated in the same manner.

In particular, during rapid discharge, Joule heat and heat generation due to changes in the crystal system of lithium cobalt oxide (LiCoO ₂ ) overlap. As a result, lithium cobalt oxide (LiCoO ₂ ) was accompanied by expansion and contraction, which was a major cause of deterioration. Therefore, in the case of lithium cobalt oxide (LiCoO ₂ ), in the past, in the case of rapid discharge, a method of not discharging to a low voltage has been common. For the above reasons, lithium cobalt oxide (LiCoO ₂ ) is the system having the highest energy density among lithium batteries, but a large amount of accumulated electricity could not be rapidly extracted.

  On the other hand, the activated carbon particles 12 of the capacitor positive electrode layer 13 are not shown, but at the time of charging, anions enter pores having a size of several nanometers together with the organic solvent, and there is a large heat generation due to entropy change. Further, during discharge, anions come out of pores having a size of several nanometers together with an organic solvent, and there is a large endotherm due to entropy change. These changes in endotherm and heat generation are completely opposite to those of the lithium-containing cobalt-based oxide particles 14. Therefore, the present invention has a technical feature that the reverse endothermic heat generation is utilized to greatly reduce deterioration.

  In the hybrid positive electrode 10 of the first embodiment shown in FIGS. 1 and 2, the lithium-containing cobalt-based oxide particles 14 of the lithium battery positive electrode layer 15 and the activated carbon particles 12 of the capacitor positive electrode layer 13 are undulated positive electrodes. It is in close contact with the current collector foil 11, and the heat transfer is clearly improved. As a result, during charging, heat generated by the lithium-containing cobalt-based oxide particles 14 is transmitted to the activated carbon particles 12 through the undulating positive electrode current collector foil 11 and absorbed.

  Moreover, at the time of discharge, the heat generation of the activated carbon particles 12 is transmitted to the lithium-containing cobalt-based oxide particles 14 through the undulating positive electrode current collector foil 11 and absorbed. Therefore, as a hybrid positive electrode, excluding Joule heat, heat absorption and heat generation are balanced and a constant temperature can be maintained. If the temperature becomes constant, it is possible to prevent deterioration of the lithium-containing cobalt-based oxide particles 14 at a high temperature and side reactions of the electrolyte solution inside the activated carbon particles 12.

  If there is no undulation of the positive electrode current collector foil 11 as shown in FIG. 2 or if the thickness of the positive electrode current collector foil is 30 to 50 μm as in a commonly used aluminum foil, heat due to rapid heat transfer The movement is difficult, and the effects of the present invention cannot be fully exhibited. The thickness of the positive electrode current collector foil 11 is desirably 7 to 15 μm, and aluminum foil is desirable from the viewpoint of malleability as a material and withstand voltage under positive electrode conditions.

  Next, a manufacturing method for making the undulations of the positive electrode current collector foil 11 as shown in FIG. 2 will be described with reference to FIG. FIG. 4 is an explanatory diagram relating to a manufacturing method for forming the undulations of the positive electrode current collector foil 11 according to Embodiment 1 of the present invention. More specifically, the hybrid positive electrode 10 is compressed by a hot roll press, and the appearance of the undulation of the positive electrode current collector foil 11 is schematically illustrated.

  The left side is a schematic cross-sectional view of the hybrid positive electrode 10 before being compressed. The heating medium temperature of the hot roll press is set to 150 ° C., and the hybrid positive electrode 10 coated and dried on both sides is passed through the hot roll press. As a result, the thin aluminum foil is rolled by being pushed by the upper and lower particles, and deforms along the shape of the upper and lower particles, and the undulation is generated exactly as shown on the right side of FIG. In addition, it is desirable that the average particle diameters of the upper and lower particles are uniform, and an ideal positive electrode current collector foil 11 that is averaged up and down is formed by rolling with the same size particles from the upper and lower sides. .

  FIG. 5 is a characteristic diagram at the time of rapid charging of the power storage device cell according to the first embodiment of the present invention. Moreover, FIG. 6 is a characteristic diagram at the time of rapid discharge of the power storage device cell in Embodiment 1 of the present invention. Specifically, FIG. 5 shows a simulation of the current flowing in the capacitor part and the lithium battery part when a quick charge is performed for 5 seconds at a constant current, and FIG. The results are shown.

  At the time of rapid charging in FIG. 5, the capacitor portion is shared at the initial stage of charging, and the sharing of the lithium battery portion increases as the voltage of the capacitor portion decreases. When charging is completed, the electric power stored in the capacitor moves to the lithium battery unit. In this way, by sharing a large current at the beginning of charging, the capacitor can suppress deterioration due to rapid charging of the lithium battery, and the charging time of the lithium battery can be kept substantially long including the charging time from the capacitor. it can. As a result, charging efficiency increases and heat generation from the lithium battery portion also decreases. This is a great effect of the power storage device including the capacitor unit and the lithium battery unit.

  In addition, the capacitor positive electrode generates heat during charging, but the lithium battery positive electrode absorbs heat, so the thermal balance is maintained, and when the capacitor positive electrode discharges and charges the lithium battery positive electrode, both of them absorb heat. . As a result, if Joule heat is removed, temperature will fall. Therefore, the deterioration of the lithium battery positive electrode during rapid charging of the lithium battery can be significantly suppressed. The same applies to the rapid discharge shown in FIG. 6, and the deterioration of the lithium battery positive electrode can be significantly suppressed.

  Next, the effect of the present invention will be described based on specific Examples 1 to 3 and Comparative Examples 1 to 3.

Example 1
[Production of hybrid positive electrode]
An electrode paste composed of activated carbon having an average particle diameter of 5 μm as a capacitor positive electrode layer, an acrylic polymer as a binder, and water as a solvent was prepared by mixing. Next, this paste was applied to one side of a current collector foil made of pure aluminum having a width of 300 mm and a thickness of 10 μm to form a capacitor positive electrode layer having a thickness of 100 μm. As a lithium battery positive electrode layer on the back surface of the aluminum current collector foil, lithium cobaltate having an average particle diameter of 5 μm, acetylene black, and polyvinylidene fluoride (PVDF) as a binder are dispersed in n-methylpyrrolidone (NMP), and 100 ° C. And dried. As a result, a lithium battery positive electrode having a thickness of 100 μm was formed, and hot roll pressing was performed at 200 ° C. to obtain a hybrid positive electrode of Example 1.

  Thereafter, hot roll pressing was performed at 180 ° C. under a linear pressure of 400 kg / cm, whereby activated carbon particles and lithium cobalt oxide particles were caused to bite into the front and back of the aluminum current collector foil. By observing the cross section with a stereomicroscope, it was observed that the aluminum current collector foil was not broken as shown in FIG.

  The total thickness of the hybrid positive electrode was 170 μm. This positive electrode is cut into a 30 mm × 50 mm strip, a 23 mm × 20 mm portion is cut from the corner, a 7 mm × 20 mm tab portion is provided, and the capacitor positive electrode and the lithium battery positive electrode layer on the front and back are peeled off, and the foil portion Was exposed to form a current terminal tab portion.

[Production of negative electrode]
An electrode paste composed of graphite particles as a negative electrode layer, polyvinylidene fluoride as a binder, and n-methylpyrrolidone as a solvent was mixed and prepared. Next, this paste was used as a negative electrode current collector foil, coated and formed on one side of a copper foil having a width of 300 mm and a thickness of 20 μm, dried, and then pressed at 105 ° C. with a calendar roll press to obtain a negative electrode. This negative electrode was cut into a 32 mm × 52 mm strip, a 20 mm × 20 mm portion was cut from the corner, and a 7 mm × 20 mm tab portion was provided to form a current terminal tab portion.

[Production of cell]
A negative electrode (electrode layer is on one side), a hybrid positive electrode, and a negative electrode (electrode layer is on one side) are laminated in order so that the electrode layers face each other, and one sheet of cellulose paper separator with a thickness of 35 μm is placed between them. Mr .. Two negative electrode current collecting tabs were overlapped, and an aluminum foil was connected to the current collecting tabs by ultrasonic welding to obtain a positive electrode current collecting terminal.

FIG. 7 is a plan configuration diagram of a power storage device cell for performance testing in Embodiment 1 of the present invention. The electrode laminate is housed in an aluminum laminate film exterior 40 as shown in FIG. 7, and an ethylene carbonate-diethyl carbonate 3: 7 mixed solvent containing 1.2 mol / l LiPF ₆ is injected as an electrolyte. Finally, the aluminum laminate exterior was sealed to obtain a test cell.

  In FIG. 7, the aluminum laminate film exterior 40 is folded in two and the three sides are heat-sealed with a thermoplastic resin (corresponding to the heat-sealing portion 50 in FIG. 7). The positive electrode current terminal portion 17 was fixed with a Kapton tape 18 with a fluororesin-coated aroma / calomel thermocouple 16.

  The current terminal portion is heat-sealed to the exterior 40 after a thermoplastic resin with improved adhesion to metal is attached. The bottom side of FIG. 7 was vacuum-evacuated and impregnated with an electrolytic solution, and finally heat-sealed and sealed.

  In FIG. 7, the exterior 40 is long even when a gas accompanying deterioration is generated from the electrode when the surface pressure is applied to the electrode portion of 3 cm × 3 cm to perform the charge / discharge test. This is because the generated gas is accumulated in the outer packaging so that the test can be continued. Note that the negative electrode is made larger than the positive electrode by 1 mm on all four sides in order to prevent measurement errors due to the deviation between the positive electrode and the negative electrode.

Cell evaluation
For this cell, a surface pressure of 5 kg / cm ² was applied to a 3 cm × 3 cm electrode portion with a stainless steel holding plate, and charged at a lower limit voltage of 2.0 V and an upper limit voltage of 4.0 V for 6 minutes in an environment of 25 ° C., 6 The charge / discharge test was repeated for 10 minutes. The temperature rise value after 10 minutes was evaluated as ΔT.

Example 2
As the capacitor positive electrode layer, activated carbon having an average particle diameter of 2 μm was used, as the lithium battery positive electrode layer, lithium cobaltate having an average particle diameter of 2 μm was used, and an aluminum foil having a thickness of 7 μm was used. And the same.

Example 3
As the capacitor positive electrode layer, activated carbon having an average particle diameter of 10 μm is used, and as the lithium battery positive electrode layer, lithium cobaltate having an average particle diameter of 10 μm is used, and an aluminum foil having a thickness of 15 μm is used. Same as 1.

Comparative Example 1
An aluminum foil having a thickness of 20 μm was used, and other than that was the same as Example 1.

Comparative Example 2
Example 1 was the same as Example 1 except that the hot-roll press of the hybrid positive electrode was not performed.

Comparative Example 3
As the capacitor positive electrode layer, activated carbon having an average particle diameter of 10 μm was used, and as the lithium battery positive electrode layer, lithium cobaltate having an average particle diameter of 2 μm was used.

  Table 1 summarizes the evaluation results comparing the temperature rise value ΔT after 10 minutes under the conditions of Examples 1, 2, 3 and Comparative Examples 1, 2, 3.

  In Table 1, when Example 1 and Comparative Example 1 are compared, Example 1 keeps the temperature of the negative electrode current collector foil as low as 15 ° C. From this, the effect of temperature rise prevention by the balance of endothermic heat generation according to the first embodiment, in particular, the effect of the thickness of the current collector foil is clear. That is, if the current collector foil is too thick, undulation does not occur even when hot roll pressing is performed, and good heat transfer cannot be maintained. In the cross-sectional stereomicrograph of Comparative Example 1, it was confirmed that there was no undulation in the aluminum current collector foil.

  In Table 1, when Example 1 and Comparative Example 2 are compared, Example 1 is kept at a lower temperature of the negative electrode current collector foil by 10 ° C. From this, the effect of the temperature rise prevention by the balance of endothermic heat generation according to the first embodiment, in particular, the effect of the hot roll press is clear. That is, unless hot roll pressing is performed, undulations do not occur and good heat transfer cannot be maintained. In the cross-sectional stereomicrograph of Comparative Example 2, it was confirmed that there was no undulation in the aluminum current collector foil.

  In Table 1, when Example 1 and Comparative Example 3 are compared, Example 1 keeps the temperature of the negative electrode current collector foil as low as 8 ° C. From this, the effect of temperature rise prevention by the balance of endothermic heat generation according to the first embodiment, in particular, the effect of the average particle diameter on the front and back sides is clear. That is, if the average particle diameters on the front and back sides are too different, undulation will not occur even with hot roll pressing, and good heat transfer cannot be maintained. In the cross-sectional stereomicrograph of Comparative Example 3, it was confirmed that the aluminum current collector foil had some undulations, but the adhesion with the particles was not good.

  In Table 1, the temperatures of the negative electrode current collector foils in Examples 1 to 3 are all kept low (the temperature increase value ΔT after 10 minutes is 9 to 18 ° C.). From this, the effect of preventing the temperature rise due to the balance of endothermic heat generation according to the first embodiment, in particular, the effect of keeping the average particle diameter on the front and back sides the same is clear. In other words, even if the aluminum current collector foil is somewhat thicker, if the front and back particle diameters are approximately the same, pressure is applied in a balanced manner from the front and back surfaces, and the current collector foil undulates according to the shape of the particles. Adhering to each other, the distance between the front and back particles is kept to the shortest, so that good heat conduction is maintained.

  As described above, in the first embodiment, the thickness of the current collector foil is preferably 7 μm to 15 μm. If the thickness is less than 7 μm, problems such as breakage of the current collector foil or opening of holes in the current collector foil occur. . When a hole is opened in the current collector foil, the electrolyte solution on the front and back sides of the positive electrode is short-circuited, and a short-circuit current flows between the activated carbon particles and the lithium cobalt oxide particles, resulting in deterioration. On the other hand, if the thickness exceeds 15 μm, the current collecting foil does not easily undulate and heat transfer is hindered.

  Further, in the first embodiment, it is desirable to perform hot roll pressing, and by heating to near the temperature at which the binder is softened, the activated carbon particles and the lithium cobalt oxide particles easily flow, and the current collector foil is undulated. Is easily formed.

  Moreover, in Embodiment 1, it is desirable that the average particle diameters on the front and back sides are approximately the same, and by pressing the particles with substantially the same size from the front and back sides, the undulations of the current collector foil are easily formed. Moreover, when the average particle diameters of the front and back are greatly different, the current collector foil is easily broken.

  In addition, in said Examples 1-3 and Comparative Examples 1-3, the case where the negative electrode layer was provided in the single side | surface of negative electrode current collection foil was shown for the test in a small cell. On the other hand, as shown in FIG. 1, it is obvious that the same effect can be obtained by providing negative electrode layers on both sides of the negative electrode current collector foil and alternately laminating them via separators. In addition, it is obvious that the same effect can be obtained even if it is made long and wound or flatly wound.

  Moreover, in said Examples 1-3 and Comparative Examples 1-3, although the case where the positive electrode layer of the front and back was the same thickness was shown, even if it differs, the same effect is acquired. Furthermore, the amount of heat generation and heat absorption during charging and discharging per unit area of the capacitor positive electrode layer is the same as the amount of heat absorption and heat generation during charging and discharging per unit area of the lithium battery positive electrode layer. Thus, if the amount of activated carbon particles and lithium-containing metal compound particles contained in the capacitor positive electrode layer and the lithium battery positive electrode layer is adjusted by the thickness and density of the positive electrode layer, the effect of preventing temperature rise according to the present invention can be obtained. Further enhanced.

  As described above, according to the first embodiment, in the power storage device positive electrode in which the capacitor positive electrode and the battery positive electrode are provided on the front and back sides of the same positive electrode current collector foil, the positive electrode current collector foil is thinned and provided with undulations. Yes. As a result, heat transfer between the capacitor positive electrode and the battery positive electrode is facilitated. Furthermore, by using a material that absorbs heat at the time of charging and generates heat at the time of discharging, the heat generation of the capacitor positive electrode at the time of charging is canceled by the heat absorption of the battery positive electrode, and the heat generation of the battery positive electrode at the time of discharging is canceled by the heat absorption of the capacitor. Can be made. Thereby, the local temperature rise and local temperature change at the time of charge are relieved, and the deterioration of the battery positive electrode which occurs when rapid charge / discharge is repeated can be prevented.

Embodiment 2. FIG.
FIG. 8 is a schematic cross-sectional view of a power storage device cell according to Embodiment 2 of the present invention. The only difference from the first embodiment is that punching metal having a large number of holes (through holes 24) is used for the negative electrode current collector foil 21.

  The large number of holes makes it possible to keep the electrochemical potential of the common negative electrode 20 constant. As a result, there is an effect that the risk of corrosion due to the local high potential or low potential of the capacitor positive electrode or the battery positive electrode can be greatly reduced.

  The negative electrode current collector foil 21 may be an etching foil in which a number of holes are partially formed by chemical etching using an expanded metal or a mask in addition to a punching metal.

  As described above, according to the second embodiment, by using the power storage device cell having a large number of holes in the negative electrode current collector foil, in addition to the effect of the first embodiment, the capacitor positive electrode or the battery positive electrode The risk of corrosion due to local high and low potentials can be greatly reduced.

Embodiment 3 FIG.
FIG. 9 is a schematic cross-sectional view of a power storage device cell according to Embodiment 3 of the present invention. The only difference from the first embodiment is that a large number of holes (through holes 25) penetrating the entire common negative electrode 20 are provided.

  A large number of holes penetrating the entire common negative electrode 20 makes it possible to keep the electrochemical potential of the common negative electrode 20 constant. As a result, there is an effect that the risk of corrosion due to the local high potential or low potential of the capacitor positive electrode or the battery positive electrode can be greatly reduced. Furthermore, since the electrolytic solution and ions can be quickly moved to the front and back separators through the front and back surfaces of the common negative electrode, the effect of preventing rapid deterioration due to rapid charge and discharge can be obtained quickly in response to the expansion and contraction of the electrodes.

  As a drilling method for the common negative electrode 20, for example, a metal mold in which quadrangular pyramid projections having a base of 0.4 mm and a height of 0.7 mm are formed at intervals of 0.8 mm, a metal plate having a smooth surface, There are a method in which the common negative electrode 20 is installed between the two and a pressing operation at a pressure of about 0.3 MPa is repeated, or a method in which a large number of holes are opened through a roller having a needle.

  The opening area of the through hole 25 is preferably 1 to 50% by area, and more preferably 5 to 20% by area with respect to the total area of the negative electrode current collector foil 21. If it is the range of 1-50 area%, both ion conductivity and electrical conductivity can be ensured. Furthermore, if it is the range of 5-20 area%, while the balance of ion conductivity and electrical conductivity will become favorable, the intensity | strength of current collection foil can fully be maintained.

  By changing the opening area, the ion conduction resistance when passing through the through hole 25 is changed. As a result, the difference in electrochemical potential between the capacitor part and the lithium battery part can be controlled. The smaller the opening area, the larger the difference in electrochemical potential and the slower the electrochemical potential of the lithium battery part. To come.

  As described above, according to the third embodiment, by using the power storage device cell having a large number of holes penetrating the entire common negative electrode, in addition to the effect of the first embodiment, the capacitor positive electrode or the battery positive electrode It is possible to significantly reduce the risk of corrosion due to local high potential and low potential, and to quickly respond to the expansion and contraction of the electrode, thereby preventing deterioration due to rapid charge and discharge.

In the first to third embodiments, the case of lithium cobaltate is shown as the lithium-containing metal compound particles. However, the present invention is not limited to this, and any lithium-containing metal compound particles that absorb heat during charging and generate heat during discharging may be used. Specifically, in addition to this, it may be a lithium cobalt oxide containing lithium nickel oxide (LiNiO ₂ ) or lithium manganese oxide (LiMn ₂ O ₄ ), which absorbs heat during charging and generates heat during discharging. A multi-component system such as a ternary system or a quaternary system may be used.

  DESCRIPTION OF SYMBOLS 10 Hybrid positive electrode, 11 Positive electrode current collection foil, 12 Activated carbon particle, 13 Capacitor positive electrode layer, 14 Lithium containing metal compound particle, 15 Battery positive electrode layer, 16 Thermocouple, 17 Positive current terminal part, 18 Kapton tape (adhesive tape) , 20 Common negative electrode, 21 Negative electrode current collector foil, 22 Capacitor negative electrode layer, 23 Lithium battery negative electrode layer, 24 Through hole (through hole of current collector foil), 25 Through hole (through hole penetrating the common negative electrode), 31 1st separator, 32 2nd separator, 40 exterior, 50 heat fusion part.

Claims (6)

A capacitor positive electrode on which one surface of the positive electrode current collector foil is formed with a capacitor positive electrode layer including activated carbon particles that generate heat during charge and absorb heat during discharge;
A positive electrode for a power storage device, comprising: a battery positive electrode layer including a battery positive electrode layer including particles of a lithium-containing metal compound that absorbs heat during charge and generates heat during discharge on the other surface of the positive electrode current collector foil. And
The positive electrode current collector foil has a thickness of 7 μm or more and less than 15 μm,
The positive electrode current collector foil sandwiched between the capacitor positive electrode layer and the battery positive electrode layer has undulations along the shape of particles contained in the capacitor positive electrode layer and the battery positive electrode layer . A positive electrode for a power storage device. The positive electrode for a power storage device according to claim 1,
An average particle size of the activated carbon particles and the lithium-containing metal compound particles is both 2 μm or more and less than 10 μm, and the average particle size is approximately the same, and the positive electrode for a power storage device. The positive electrode for a power storage device according to claim 1 or 2,
The amount of the activated carbon particles contained in the capacitor positive electrode layer and the amount of the lithium-containing metal compound particles contained in the battery positive electrode layer are determined during charging and discharging per unit area of the capacitor positive electrode layer. The power storage, wherein the heat generation amount and the heat absorption amount in each of the battery positive electrode layer and the heat absorption amount and the heat generation amount at the time of charging and discharging per unit area of the battery positive electrode layer are adjusted to be the same Positive electrode for devices. The positive electrode for a power storage device according to any one of claims 1 to 3,
The electrode for a power storage device, wherein the lithium-containing metal compound contains a cobalt oxide. A capacitor positive electrode on which one surface of the positive electrode current collector foil is formed with a capacitor positive electrode layer including activated carbon particles that generate heat during charge and absorb heat during discharge;
On the other surface of the positive electrode current collector foil, a battery positive electrode formed with a battery positive electrode layer containing particles of a lithium-containing metal compound that absorbs heat during charging and generates heat during discharging, and
The positive electrode current collector foil has a thickness of 7 μm or more and less than 15 μm,
The positive electrode current collector foil sandwiched between the capacitor positive electrode layer and the battery positive electrode layer has undulations along the shape of particles contained in the capacitor positive electrode layer and the battery positive electrode layer . A method for producing a positive electrode for a storage device, comprising:
The manufacturing method of the positive electrode for electric power storage devices characterized by including the step of forming the undulation of the said positive electrode current collection foil by hot roll press. A capacitor positive electrode layer formed on one surface of the positive electrode current collector foil with a capacitor positive electrode layer containing activated carbon particles that generate heat during charge and absorb heat during discharge; and the other surface of the positive electrode current collector foil absorbs heat during charge. And a positive electrode current collector foil having a thickness of 7 μm or more and less than 15 μm, wherein the positive electrode current collector foil has a thickness of 7 μm or more and less than 15 μm. The positive electrode current collector foil sandwiched between an electrode layer and the battery positive electrode layer has an undulation along the shape of particles contained in the capacitor positive electrode layer and the battery positive electrode layer . A positive electrode;
A negative electrode layer is formed on both surfaces of the negative electrode current collector foil, and the common negative electrode having a through hole penetrating only the current collector foil or the entire negative electrode,
The power storage device cell, wherein the positive electrode for the power storage device and the common negative electrode are alternately stacked or wound via a separator.

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