JP4921594B2 - Secondary battery current collector paste, secondary battery current collector and method for producing the same, secondary battery electrode, secondary battery - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a paste for forming a current collector for a secondary battery, a current collector for a secondary battery and a method for producing the same, an electrode for a secondary battery, and a secondary battery, and lithium having excellent rapid charge / discharge characteristics. The present invention relates to a high-performance material capable of providing an ion secondary battery.

Lithium-ion secondary batteries are high-performance secondary batteries, and because of their high energy density, they are currently used in applications such as mobile phones, notebook computers, and video cameras, and the market is greatly expanding. Of these lithium ion batteries, small batteries generally use lithium cobaltate or lithium manganate as the positive electrode active material and graphite as the negative electrode. Furthermore, polypropylene, a porous separator is a sheet of polyethylene or the like, such as ethylene carbonate-based solution of lithium hexafluorophosphate as an electrolyte (LiPF _6), and an organic solution of lithium salt is dissolved.

  More specifically, the positive electrode of a general lithium ion secondary battery is composed of lithium cobaltate or lithium manganate as a positive electrode active material, and carbon fine particles having electron conductivity for transporting electrons from here (here). Is fixed on a metal foil having a current collecting effect. At this time, aluminum is generally used as the metal foil, and polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE) is used as a binder to fix the positive electrode active material and the carbon fine particles. It is used.

  In recent years, there has been an active movement to apply such high-performance secondary batteries to fields that require power, such as automobiles. For this reason, problems that have not been anticipated with small batteries have occurred.

  One of them is rapid charge / discharge characteristics. In order to require power, a large amount of current is required. Therefore, since the capacity of the battery is exhausted immediately, it becomes necessary to newly charge the battery. If the charging time is set long, the battery cannot be used during that time, so charging must be completed quickly with as much current as possible. The discharge performance and the charge performance at such a large current value are referred to as rapid charge / discharge characteristics and are important performance indexes of the secondary battery.

  In order to perform rapid charge / discharge, it is essential to increase the current value as described above. However, in the current lithium ion secondary battery, when charging / discharging is performed with a large current, there is a problem in that a decrease in capacity (initial battery capacity maintenance ratio) when charging / discharging is extremely reduced. That is, when charging and discharging are repeated with a large current, the power decreases. More specifically, charging / discharging at 1 C (current value capable of charging / discharging the battery capacity in one hour) is possible, but at 20 C (current value 20 times the current value capable of charging / discharging the battery capacity in one hour), it is almost impossible. The current situation is that it is possible, and many attempts have been made to improve such problems as described in the following document.

JP 2001-266850 A Japanese Examined Patent Publication No. 7-123053 Patent No. 1989293 The 45th Battery Discussion (2004) 3C18

  However, none of the techniques described in the above-mentioned documents is sufficient to improve the above-mentioned problems.

  The present invention has been made in view of the above circumstances, and allows for rapid charging and discharging, and formation of a secondary battery current collector for a lithium secondary battery having a high initial battery capacity retention rate at a high rate (high current value). An object of the present invention is to provide a paste for a battery, a current collector for a secondary battery and a method for producing the same, an electrode for a secondary battery, and a secondary battery.

As a result of intensive studies to achieve the above object, the present inventor has made a positive electrode current collector that distributes lithium ion conductivity to a specific compound and electronic conductivity to electron conductive carbon particles, particularly in the positive electrode structure. It has been found that the above problems can be solved by using a body structure, and the present invention has been made. That is, the present invention relates to the following.
(1) (a) a film-forming compound comprising a polysaccharide polymer and a crosslinking agent,
A paste for forming a current collector for a secondary battery, comprising (b) carbon fine particles, and (c) a solvent.
(2) The paste for forming a current collector for a secondary battery as described in (1) above, wherein the polysaccharide polymer is chitosan or chitin.
(3) The paste for forming a current collector for a secondary battery according to any one of (1) or (2), wherein the crosslinking agent is an acid anhydride.
(4) The paste for forming a current collector for a secondary battery as described in (3) above, wherein the acid anhydride is trimellitic anhydride or pyromellitic anhydride.
(5) The paste for forming a current collector for a secondary battery according to any one of items 1 to 4, wherein the carbon fine particles include needle-shaped or rod-shaped carbon fine particles.
(6) A step of forming a film made of the paste for forming a current collector for a secondary battery according to any one of items 1 to 5 on an aluminum foil or a copper foil; and
The manufacturing method of the electrical power collector for secondary batteries including the process of scattering the solvent of this membrane | film | coat.
(7) A current collector for a secondary battery manufactured using the paste for forming a current collector for a secondary battery according to any one of items 1 to 5.
(8) An electrode for a secondary battery comprising the current collector according to item 7 above and a film containing an active material.
(9) A secondary battery comprising the electrode according to item 8 above.

  The secondary battery current collector, the secondary battery electrode, and the secondary battery manufactured using the paste for forming a secondary battery current collector according to the present invention have an improved initial capacity maintenance rate at a high rate. Since it is greatly improved, it can be suitably used for a secondary battery having excellent rapid charge / discharge characteristics.

It is the schematic which shows the collector sectional structure which concerns on the lower layer of Example 1 of this invention. It is the schematic which shows the positive electrode cross-section based on Example 2 of this invention.

  Hereinafter, the present invention will be described in more detail. In the present specification, aluminum means aluminum and aluminum alloy. Copper means pure copper and copper alloy.

  The aluminum foil that can be used in the present invention is not particularly limited, and various types such as a pure aluminum-based A1085 material and A3003 material can be used. The thickness is preferably about 5 μm to 100 μm. The same applies to the copper foil, and a rolled copper foil or an electrolytic copper foil is preferably used. In the present invention, the aluminum foil is used on the positive electrode side, and the copper foil is used on the negative electrode side.

  If the thickness of the aluminum foil and the copper foil is 5 μm or less, there is a risk that the foil may be broken in the coating process for forming the current collecting layer due to insufficient strength. On the other hand, if the thickness exceeds 100 μm, This is not preferable because the ratio of the foil increases and the battery capacity decreases.

The positive electrode active material used in the present invention is not particularly limited as long as it is a substance capable of inserting and extracting lithium (ions). Specifically, lithium cobaltate (LiCoO ₂ ), lithium manganate (LiMn ₂ O 4), lithium nickelate (LiNiO ₂ ), and ternary lithium compounds of Co, Mn, and Ni ( Li (CoxMnyNiz) O ₂ ), sulfur-based (TiS ₂ ), olivine-based (LiFePO ₄ ) and the like are suitable.

  Moreover, as a particle diameter of these positive electrode active materials, 1-50 micrometers is preferable. A particle diameter of 50 μm or more is not preferable because non-uniformity in lithium insertion / extraction occurs inside and outside the particle. On the other hand, when the thickness is 1 μm or less, the crystallinity is lowered and the particle structure is disturbed, so that the performance is lowered, which is not preferable.

  A well-known thing can be used as a negative electrode active material used for a negative electrode. There are no particular restrictions on graphite, such as graphite, amorphous graphite, and oxide.

  An ion-permeable compound that can be used in the present invention, a compound that is not swellable with respect to an organic solvent, a compound that does not peel off in a peeling test with an organic solvent, a compound that does not peel off in a tape peeling (hereinafter collectively referred to as film formation) The following can be used as the compound for use).

  As the ion-permeable compound, any material (including the compound) having a performance capable of simply transmitting ions may be used.For example, a crosslinked polymer of cellulose and acrylamide and a crosslinked polymer of cellulose and chitosan pyrrolidone carboxylate are suitable. Yes. In addition to these, polysaccharide polymers such as chitosan and chitin which are crosslinked with a crosslinking agent can be used. Suitable crosslinking agents that can be used include acrylamide, acrylonitrile, chitosan pyrrolidone carboxylate, hydroxypropyl chitosan, or acid anhydrides such as phthalic anhydride, maleic anhydride, trimellitic anhydride, and pyromellitic anhydride. ing.

From the viewpoint of battery performance, those having high ionic conductivity are preferred. In particular, a lithium ion having a high conductivity is preferable, and a compound having a lithium ion conductivity of 1 × 10 ⁻² S / cm or more is preferable. Alternatively, a compound having a fluorine ion conductivity of 1 × 10 ⁻² S / cm or more is also suitable.

  Alternatively, as the film forming compound, among the above compounds, those having resistance to an organic solvent and firmly adhering to the metal foil are preferable. The reason for this is that in lithium ion batteries, an organic electrolytic solution is usually used as the electrolytic solution, so that the formed film is dissolved in the electrolytic solution.

  In general, polyamides, polyamideimides and the like are known as compounds having resistance to organic solvents, but these are very expensive and impractical. Furthermore, these average molecular weights are as small as about 50000, and the adhesiveness with respect to metal foil is not enough. On the other hand, when the average molecular weight is 50000 or more, the above-mentioned PVDF, PTFE, and the like are present, and the metal foil has sufficient adhesion, but these swell in the organic solvent, and the resistance to the organic solvent is very weak. is there. Accordingly, those having an average molecular weight of 50,000 or less, high adhesion to the metal foil, and extremely high resistance to organic solvents are suitable.

  As a scale for measuring these performances, it can be judged by swelling property with respect to a solvent, a peeling test (rubbing test) with a cloth soaked with a solvent, and a tape peeling test (JIS D0202-1988).

  Examples of the material exhibiting the above characteristics include those obtained by crosslinking polysaccharide polymer polymers with acrylic additives and acid anhydrides, and those based on chitosan derivatives.

The electron conductive carbon fine particles that can be used in the present invention are not particularly limited, but acetylene black, ketjen black, vapor grown carbon fiber, graphite (graphite) and the like are suitable. In particular, it is preferable that the electrical resistance of the powder is 100% green compact and 1 × 10 ⁻¹ Ω · cm or less, and the above can be used in combination as necessary.

  In the above-mentioned electron conductive carbon fine particles, the particle size is not particularly limited, but is generally 10 to 100 nm. Furthermore, it is more preferable that the shape is not spherical but has anisotropy such as a needle shape or a rod shape. The reason is described below. The electron conductive carbon fine particles share the movement of electrons in the lithium ion secondary battery. At the time of charging, it is necessary to allow electrons supplied from the outside to reach the positive electrode active material through the aluminum foil, so it is desired to increase the contact area between the aluminum foil and the positive electrode active material. For this purpose, fine particles having a large surface area per mass are more advantageous. Moreover, it must be achieved with as little amount as possible to ensure battery capacity. Therefore, electron conductive carbon fine particles having anisotropy in shape are suitable.

  In the present invention, there is no particular limitation on the preparation of the film containing the film forming compound and the carbon fine particles, and a known method can be used. Specifically, there are a casting method, a bar coater method, a dip method, a printing method, and the like. Of these methods, the bar coater method, the cast method and the like are preferable because the thickness of the film can be easily controlled. A current collector (for positive electrode or negative electrode) can be obtained by forming a carbon fine particle-containing film on an aluminum foil or copper foil by the above method. Further, the thickness is preferably 0.1 μm or more and 10 μm or less. If the thickness is 0.1 μm or less, the desired effect cannot be obtained, which is not preferable. On the other hand, when the thickness is 10 μm or more, the ratio of the active material in a predetermined volume of one secondary battery is relatively decreased, which is not preferable.

  On the other hand, when a film containing a positive electrode active material or a negative electrode active material is formed, the same method can be used. The film thickness is preferably 10 μm or more and 500 μm or less. A film thickness of 10 μm or less is not preferable because the ratio of the active material in a predetermined volume of one battery decreases and the battery capacity decreases. On the other hand, when the thickness is 500 μm or more, detachment from the foil and the internal resistance of the battery increase, such being undesirable.

  Hereinafter, the case where a film containing a positive electrode active material is formed will be described in more detail. In the case of a film containing a negative electrode active material, the same can be applied by replacing the aluminum foil with a copper foil and the positive electrode active material with a negative electrode active material in the following description.

  The composition ratio of the film is adjusted at the stage of the paste for forming the film. Specifically, it is prepared by mixing a film-forming compound, carbon fine particles, a positive electrode active material and the like with a kneader or the like, and further adding a solvent for viscosity adjustment. In addition, since the solvent is scattered in a subsequent step, only solid content (film forming compound, carbon fine particles, positive electrode active material) remains in the film. These ratios are generally in terms of mass ratio, preferably 1% to 30% by mass of the film-forming compound, 1% to 30% by mass of the carbon fine particles, and 65% by mass or more of the positive electrode active material.

  The thickness of the film is preferably 0.1 μm or more and 500 μm or less. If the thickness is 0.1 μm or less, the desired effect cannot be obtained. On the other hand, when the thickness is 500 μm or more, there is a risk of cracking of the film, dropping from the aluminum foil, and the like, which is not preferable.

  In the present invention, a current collector may be provided in which an aluminum foil is provided with two layers of a lower layer and an upper layer. At this time, a film containing the film-forming compound and carbon fine particles is used as a lower layer, and a film containing a binder, carbon fine particles and a positive electrode active material is used as an upper layer. The binder contained in the upper layer only needs to have an effect of fixing particles, and may include a film-forming compound such as a polysaccharide polymer polymer crosslinked with an acrylic additive, or a commonly used compound such as polyfluoride. Vinylidene (PVDF) or polytetrafluoroethylene (PTFE) may be included.

  The battery evaluation of the current collector for the secondary battery according to the present invention can be performed by forming the current collector into an electrode and configuring a secondary battery including a known separator and organic electrolyte.

  Furthermore, the performance of the secondary battery according to the present invention can be evaluated by mounting it on a moving body (vehicle such as an automobile or bicycle) or a power electric tool (electric drill, impact wrench, etc.).

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated concretely, this invention is not limited to the following Example.

Example 1
An aluminum foil having a thickness of 30 μm made of A1085 material was prepared. Next, a polysaccharide polymer polymer chitosan crosslinked with pyromellitic anhydride was prepared as an ion-permeable compound. This molecular weight was 35000 by GPC measurement. Using this, a mixed paste with carbon fine particles (acetylene black: particle size 40 nm) having electronic conductivity was prepared. The solvent was water, and the mass ratio of the ion-permeable compound, the carbon fine particles, and water was 35:15:50. Next, using an applicator (gap: 10 μm), this paste was applied onto an aluminum foil by a casting method, and then dried in air at 180 ° C. for 3 minutes, followed by thermosetting to make the ion permeability. The aluminum foil provided with the film | membrane containing the compound which has and a carbon microparticle was obtained.

  When the thickness of this film was measured after drying, the thickness was 5 μm, and the content of carbon fine particles having electronic conductivity in the film was 30% by mass.

  Next, a positive electrode paste made of a positive electrode active material, electron conductive carbon fine particles, a binder, and a solvent was used to form an electrode layer having a thickness of 200 μm to obtain a positive electrode for a lithium ion secondary battery. At this time, lithium cobaltate was used as the positive electrode active material, acetylene black as the conductive carbon fine particles, polyvinylidene fluoride (PVDF) as the binder, and N-methyl-2-pyrrolidone (NMP) as the solvent. The composition ratio of each component was positive electrode active material: carbon fine particles: binder = 95: 2: 3 (mass ratio), and the solvent was 10% by mass of the positive electrode active material mass.

  Furthermore, the separator and the negative electrode formed on the copper foil were incorporated, and these were impregnated with an organic electrolyte solution to obtain a lithium ion secondary battery.

  The cycle characteristics of the lithium ion secondary battery obtained above were measured. The results are shown in Table 1. The measuring device used was a battery charging / discharging device HJ-2010 type manufactured by Hokuto Denko Co., Ltd., and the initial capacity maintenance rate after 100 cycles was displayed as a percentage by changing the current rate to 0.1C, 2C, and 20C. As can be seen from the table, a large difference was not observed when the current rate was small. However, the use of the current collector according to the present invention significantly improved the initial capacity maintenance ratio on the high rate side. I understand that. That is, the rapid charge / discharge characteristics are excellent.

  Moreover, the internal resistance of the secondary battery was measured. The measurement was carried out by an AC impedance method using a HIOKI3551 battery tester at a measurement frequency of 1 kHz. The measurement results are shown in Table 2. The smaller the measured value, the better the quick charge / discharge performance.

(Example 2)
An aluminum foil having a thickness of 30 μm made of A1085 material was prepared. Next, a polysaccharide polymer polymer chitin crosslinked with maleic anhydride was prepared as a compound having ion permeability. This molecular weight was 30000 by GPC measurement. Using this, carbon fine particles having electron conductivity (acetylene black: particle diameter 40 nm) and a paste made of lithium manganate (LiMn ₂ O ₄ ) and a solvent (NMP) as a positive electrode active material were prepared. The composition ratios of the ion-permeable compound, the carbon fine particles, and the positive electrode active material in the paste were 2 mass%, 3 mass%, and 95 mass%, respectively, and the solvent was 10 mass% of the positive electrode active material. Next, this paste was applied onto an aluminum foil using an applicator (gap: 250 μm) in the same manner as in Example 1, and then dried in air at 180 ° C. for 3 minutes, followed by thermosetting, An aluminum foil provided with a film containing a permeable compound, carbon fine particles, and a positive electrode active material was obtained.

  When the thickness of this film was measured after drying, the thickness was 200 μm, and the contents of the carbon fine particles having electron conductivity and the positive electrode active material in the film were 3% by mass and 95% by mass, respectively.

Thereafter, the separator and the negative electrode current collector formed on the copper foil were incorporated by the same process as in Example 1, and the organic electrolyte was impregnated therein to obtain a lithium ion secondary battery.
Similarly, the initial capacity retention ratio and the internal resistance were measured, and the results are shown in Table 1 and Table 2, respectively.

(Example 3)
In Example 2, the material of the aluminum foil was changed from the A1085 material to the A3003 material, and instead of the compound having ion permeability, chitosan, which is a polysaccharide polymer polymer, was cross-linked with acrylonitrile as a compound that did not peel in an organic solvent peel test. I prepared what I did. When this compound was formed into a film having a thickness of 0.5 μm and subjected to a peel test with ethyl alcohol as an organic solvent, no peel was observed. Moreover, this molecular weight was 31000 by GPC measurement. Moreover, it was set as the vapor-phase-grown carbon fiber (made by Showa Denko, trademark registration name VGCF) as carbon fine particles. The positive electrode active material was changed to olivine (LiFePO ₄ ).
Furthermore, the addition amount of the carbon fine particles was changed, and the composition ratios of the compound, the carbon fine particles, and the positive electrode active material that did not peel in the peel test using the organic solvent in the paste were 2 mass%, 1 mass%, and 97 mass%, respectively.

  Except for this, a lithium ion secondary battery was obtained in the same manner as in Example 2. Similarly, the initial capacity retention ratio and the internal resistance were measured, and the results are shown in Table 1.

Example 4
In Example 1, as a compound that does not swell with respect to NMP instead of an ion-permeable compound, a polysaccharide polymer polymer chitosan was crosslinked with trimellitic anhydride, and a solvent in which NMP was used was prepared. . This molecular weight was 22000 by GPC measurement.

  A lithium ion secondary battery was obtained in the same manner as in Example 1 except that this was used. Similarly, the initial capacity retention ratio and the internal resistance were measured, and the results are shown in Tables 1 and 2, respectively.

(Example 5)
A copper foil having an electrolytic copper foil thickness of 9 μm was prepared. Next, a polysaccharide polymer polymer cellulose crosslinked with chitosan pyrrolidone carboxylate was prepared as an ion-permeable compound. This molecular weight was 40000 by GPC measurement. Using this, a mixed paste with carbon fine particles (acetylene black: particle size 40 nm) having electronic conductivity was prepared. The solvent was NMP, and the mass ratio of the ion-permeable compound, the carbon microparticles, and the solvent was 35:15:50. Next, this paste is applied onto a copper foil by a gravure method using a gravure roll (# 200), then dried in air at 180 ° C. for 3 minutes, and thermally cured to have ion permeability. A copper foil (current collector) provided with a film containing the compound and carbon fine particles was obtained.

  When the thickness of this film was measured after drying, the thickness was 0.2 μm, and the content of carbon fine particles having electronic conductivity in the film was 30% by mass.

  Next, an electrode layer having a thickness of 250 μm was formed using a negative electrode paste made of a negative electrode active material, electronically conductive carbon fine particles, a binder, and a solvent to obtain a negative electrode for a lithium ion secondary battery. At this time, graphite was used as the negative electrode active material, acetylene black as the conductive carbon fine particles, polyvinylidene fluoride (PVDF) as the binder, and N-methyl-2-pyrrolidone (NMP) as the solvent. The composition ratio of each component was negative electrode active material: carbon fine particles: binder = 92: 5: 3 (mass ratio), and the solvent was 10% by mass of the negative electrode active material mass.

  Thereafter, a separator and a positive electrode formed on the aluminum foil used in Example 1 were incorporated by the same process as in Example 1, and these were impregnated with an organic electrolyte solution to obtain a lithium ion secondary battery. Similarly, the initial capacity retention ratio and the internal resistance were measured, and the results are shown in Tables 1 and 2, respectively.

(Example 6)
Instead of the compound having ion permeability in Example 5, a compound obtained by crosslinking chitosan, which is a polysaccharide polymer, with acrylonitrile as a compound that does not peel off in a tape peeling test was prepared. When this compound was formed to a thickness of 0.5 μm and a tape peeling test was conducted, it was 100/100 and no peeling was observed. Moreover, this molecular weight was 26000 by GPC measurement. Moreover, it was set as the vapor-phase-grown carbon fiber (made by Showa Denko, trademark registration name VGCF) as carbon fine particles. Except for this, a lithium ion secondary battery was obtained in the same manner as in Example 5. Similarly, the initial capacity retention ratio and the internal resistance were measured, and the results are shown in Tables 1 and 2, respectively.

(Comparative Example 1)
In Example 1, the positive electrode active material (lithium cobaltate) and electronic conductivity shown in Example 1 were not formed on the A1085 material without forming a composite film composed of an ion-permeable compound and carbon particles having electronic conductivity. A current collector layer composed of conductive carbon fine particles (acetylene black), a binder (PVDF), and a solvent (NMP) was formed to a thickness of 200 μm to obtain a positive electrode current collector. Hereinafter, lithium ion secondary batteries were prepared in the same manner, and the initial capacity retention ratio and internal resistance were measured under the same conditions as in Example 1, and are shown in Tables 1 and 2, respectively.

(Comparative Example 2)
In Example 5, a lithium ion secondary battery was prepared in the same manner as in Example 1 except that the PVDF binder (a compound that peeled off in a peel test using an organic solvent) was used instead of the compound having ion permeability. The initial capacity retention rate and the internal resistance were measured under the same conditions as in Example 1, and are shown in Tables 1 and 2, respectively. Although it was possible to process to a secondary battery, when the surface of the current collector was rubbed with a cloth dipped in NMP at the stage of the current collector provided with a film containing carbon fine particles, a large peeling occurred. . Even if the initial characteristics are good, it can be measured that the secondary battery cannot withstand long-term use.

(Comparative Example 3)
In Example 1, a lithium ion secondary battery was prepared in the same manner as in Example 1 except that a PVA (polyvinyl alcohol) binder (a compound that peeled off in the tape peeling test) was used instead of the compound having ion permeability. The initial capacity retention ratio and the internal resistance were measured under the same conditions as in Example 1, and are shown in Tables 1 and 2, respectively. Although it was possible to process to a secondary battery, a tape peeling test was performed at the stage of a current collector provided with a film containing carbon fine particles, and the current collector surface was largely peeled off. Even if the initial characteristics are good, it can be measured that the secondary battery cannot withstand long-term use.

According to Table 1, in the comparative example, the initial capacity retention rate at the low rate is not inferior to that of the example in the present invention, but the initial capacity retention rate is significantly lowered at the high rate.
That is, it turns out that rapid charge / discharge is difficult.
Table 2 also shows that the secondary battery has a low internal resistance and is suitable for rapid charge / discharge.

  The reason why the present invention is excellent in rapid charge / discharge characteristics is that the ion-permeable binder and the electronically conductive carbon fine particles share the movement of ions and the movement of the battery, respectively. This is probably because the film and the electrode film are firmly adhered.

  The present invention provides a paste for forming a current collector for a secondary battery, a current collector for a secondary battery using the paste, a method for producing the current collector, an electrode for a secondary battery, and a secondary battery. In particular, a specific paste containing a film-forming compound comprising a polysaccharide polymer polymer and a crosslinking agent, carbon fine particles, and a solvent, and a current collector for a secondary battery using the paste and a related invention When the battery is configured, the improvement of the initial capacity maintenance rate at a high rate can be greatly improved, and the rapid charge / discharge characteristics are excellent, so in communication equipment and digital home appliances equipped with secondary batteries, etc. It can be used suitably. Due to this characteristic, the application of the device equipped with the secondary battery is expanded and the industrial use range can be expanded more than expected.

1 ... Aluminum foil,
2 ... ion-permeable compound,
3 ... carbon fine particles,
4 ... Composite film,
5 ... Positive electrode active material,

Claims (7)

(A) a film-forming compound obtained by crosslinking chitosan with an acid anhydride or acrylonitrile ;
A paste for forming a current collector for a secondary battery, comprising (b) carbon fine particles, and (c) a solvent. The paste for forming a current collector for a secondary battery according to claim 1 , wherein the acid anhydride is trimellitic anhydride or pyromellitic anhydride. The paste for forming a current collector for a secondary battery according to claim 1 or 2 , wherein the carbon fine particles include needle-shaped or rod-shaped carbon fine particles. The process of forming the membrane | film | coat which consists of the paste for the collectors for secondary batteries of any one of Claims 1-3 on aluminum foil or copper foil, and
The manufacturing method of the electrical power collector for secondary batteries including the process of scattering the solvent of this membrane | film | coat. Current collector for a secondary battery manufactured using the secondary battery current collector forming paste according to any one of claims 1-3. An electrode for a secondary battery comprising the current collector according to claim 5 and a film containing an active material. A secondary battery comprising the electrode according to claim 6 .

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