JP6679895B2 - Electric storage element and manufacturing method thereof - Google Patents

Description

  The present invention relates to a storage element and a method for manufacturing the same.

  Conventionally, for example, Patent Document 1 proposes a configuration in which an inorganic oxide layer is provided on the surface of a positive electrode active material. The positive electrode active material constitutes the positive electrode of a rechargeable secondary battery. The inorganic oxide layer plays a role of suppressing the reaction between the positive electrode active material and the electrolyte solution substance when a voltage is applied to the positive electrode active material.

JP, 2014-116111, A

  However, in the above conventional technique, since the inorganic oxide layer is composed of an insulating material, when an electrode is produced using a positive electrode active material provided with the inorganic oxide layer, the electron conductivity in the electrode is lowered. Will end up. Therefore, there is a problem that the battery performance is deteriorated.

  In view of the above points, the present invention provides a power storage device capable of improving battery performance by suppressing generation of a resistance component in a reaction between a positive electrode and an electrolyte substance while ensuring electronic conductivity of the positive electrode active material. This is the first purpose. A second object is to provide a method for manufacturing the power storage element.

In order to achieve the above object, in the invention according to claim 1 , a positive electrode (40) containing a positive electrode active material (42) capable of occluding and releasing metal ions as a main component, and a negative electrode active material capable of occluding and releasing metal ions. And a negative electrode (50) containing (52) as a main component. Further, it is sandwiched between the positive electrode and the negative electrode, and has a separator (60) which has conductivity of metal ions and electrically insulates and separates the positive electrode and the negative electrode.

  Further, it is provided with a positive electrode terminal (20) connected to the positive electrode and a negative electrode terminal (30) connected to the negative electrode. The housing (10) accommodates the separator, the positive electrode, the negative electrode, a part of the positive electrode terminal, and a part of the negative electrode terminal in the accommodation chamber (18) with the separator sandwiched between the positive electrode and the negative electrode. Further, in the storage chamber, a metal oxide coating film (71) covering the entire wall surface (19) of the storage chamber, the separator, the positive electrode, the negative electrode, a part of the positive electrode terminal, and a part of the negative electrode terminal. ) Is provided.

According to the invention of claim 5 , a positive electrode (40) containing a positive electrode active material (42) capable of inserting and extracting metal ions as a main component is prepared. Further, a negative electrode (50) containing a negative electrode active material (52) capable of inserting and extracting metal ions as a main component is prepared.

  Next, a separator (60) having metal ion conductivity and electrically insulating and separating the positive electrode and the negative electrode is prepared, and the separator is sandwiched between the positive electrode and the negative electrode. Then, the positive electrode terminal (20) is connected to the positive electrode. Further, the negative electrode terminal (30) is connected to the negative electrode.

  Subsequently, the housing (10) having the accommodation chamber (18) is prepared, and the separator, the positive electrode, the negative electrode, a part of the positive electrode terminal, and a part of the negative electrode terminal are accommodated in the accommodation chamber. After that, a metal oxide film (which covers the entire wall surface (19) of the accommodation chamber, the separator, the positive electrode, the negative electrode, a part of the positive electrode terminal, and a part of the negative electrode terminal in the accommodation chamber ( 71) is formed.

  As described above, since the first coating of the metal oxide covers the entire surface of the positive electrode, it is possible to prevent the first coating from intervening in the current path of the positive electrode active material. Therefore, the electron conductivity of the positive electrode active material can be secured. Further, since the positive electrode active material does not come into contact with the electrolytic solution by the first coating, it is possible to suppress the generation of the resistance component in the reaction between the electrolytic material contained in the electrolytic solution and the positive electrode active material. Therefore, deterioration of the battery performance of the power storage element can be suppressed.

  It should be noted that the reference numerals in parentheses for each means described in this column and in the claims indicate the correspondence with the specific means described in the embodiments described later.

FIG. 3 is a perspective view of the electricity storage device according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view of the electricity storage device shown in FIG. 1. FIG. 3 is an enlarged cross-sectional view of the positive electrode, the negative electrode, and the separator shown in FIG. 2. It is a figure showing a manufacturing process of a storage element concerning a 1st embodiment. It is a figure showing the correlation of the cycle number and capacity maintenance rate. FIG. 6 is a diagram showing a correlation between a capacity per active material and a voltage. It is an expanded sectional view of a positive electrode, a negative electrode, and a separator concerning a 2nd embodiment of the present invention. It is a figure showing the manufacturing process of the electric storage element concerning a 2nd embodiment. It is an expanded sectional view near the positive electrode terminal among the electric storage elements concerning a 3rd embodiment. It is a figure showing a manufacturing process of a storage element concerning a 3rd embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following respective embodiments, the same or equivalent parts are designated by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The electricity storage device according to the present embodiment is a secondary battery in which charge and discharge are realized by the movement of charges due to electrolyte ions between the positive and negative electrodes. The electrolyte ions are metal ions such as lithium ions.

  As shown in FIGS. 1 and 2, the electricity storage device 1 includes a housing 10, a positive electrode terminal 20, a negative electrode terminal 30, a plurality of positive electrodes 40, a plurality of negative electrodes 50, and a plurality of separators 60. . Note that in FIG. 3, the cross section of the separator 60 is represented by a broken line in order to make the laminated structure of the laminated body 70 easy to see. The separator 60 is actually a sheet.

  The electricity storage device 1 is of a laminate type in which a laminate 70 is sealed in laminate films 11 and 12 that form the housing 10. The laminated body 70 is accommodated in the recesses 13 and 14 formed in the laminated films 11 and 12 by embossing or the like.

  The laminated body 70 is configured by further laminating a plurality of the positive electrodes 40 and the negative electrodes 50 that are laminated via the separator 60. The laminated body 70 has a rectangular parallelepiped shape including a surface slightly smaller than the bottom surfaces of the recesses 13 and 14. The uppermost layer and the lowermost layer of the laminated body 70 are the negative electrode 50.

  The outer peripheral edge 15 of each of the laminate films 11 and 12 is a surface located at the outer edge of the recesses 13 and 14 and abutting against each other. The outer peripheral edge 15 is joined by a method such as heat fusion.

  The positive electrode terminal 20 and the negative electrode terminal 30 are sealed at the outer peripheral edge 15 of the laminate films 11 and 12 via tab films 16 and 17. The tab films 16 and 17 are made of, for example, acid-modified polypropylene or the like. Since the tab films 16 and 17 have polarities, they have adhesiveness.

  One end of the positive electrode terminal 20 is connected to the plurality of positive electrodes 40, and the other end thereof projects outside the outer peripheral edge 15. Similarly, the negative electrode terminal 30 has one end connected to the plurality of negative electrodes 50 and the other end protruding outside the outer peripheral edge 15.

  Therefore, the housing 10 houses the laminated body 70, a part of the positive electrode terminal 20, and a part of the negative electrode terminal 30 in the housing chamber 18 formed by the recesses 13 and 14 of the laminate films 11 and 12, respectively. . The tab films 16 and 17 form a part of the wall surface 19 of the housing chamber 18 of the housing 10.

  As shown in FIG. 3, the positive electrode 40 has a positive electrode current collector 41, a positive electrode active material 42, a conductive material 43, and a first coating film 44. Further, the negative electrode 50 has a negative electrode current collector 51, a negative electrode active material 52, and a second coating 53.

  Specifically, the positive electrode 40 is formed by laminating a positive electrode active material 42 as an oxidizing agent on both surfaces of a positive electrode current collector 41 made of aluminum foil. The positive electrode 40 has this positive electrode active material 42 as a main component. The negative electrode 50 is obtained by laminating a negative electrode active material 52 as a reducing agent on both surfaces of a negative electrode current collector 51 made of copper foil. The negative electrode 50 has this negative electrode active material 52 as a main component.

  The positive electrode current collector 41 and the negative electrode current collector 51 serve as terminals for extracting electricity. A plurality of positive electrode current collectors 41 are bundled and connected to one end side of the positive electrode terminal 20. Similarly, a plurality of negative electrode current collectors 51 are bundled and connected to one end side of the negative electrode terminal 30.

  The positive electrode active material 42 and the negative electrode active material 52 are materials that perform an oxidation / reduction reaction by sending out and receiving metal ions. That is, the positive electrode active material 42 and the negative electrode active material 52 are compounds capable of inserting and extracting lithium ions as metal ions.

As the positive electrode active material 42, for example, lithium cobalt oxide (LiCoO ₂ ), lithium iron phosphate (LiFePO ₄ ), lithium manganate (LiMnPO ₄ ), LiNi _0.5 Mn _1.5 O ₄ or the like is used. As the negative electrode active material 52, for example, carbon (C), lithium titanate (Li ₄ Ti ₅ O ₁₂ ) or the like is used.

  The conductive material 43 plays a role of providing an electron supply path to the positive electrode active material 42. As the conductive material 43, for example, a carbon material, metal powder, conductive polymer or the like is used.

  The first coating film 44 is a film that plays a role of suppressing the reaction between the positive electrode current collector 41, the positive electrode active material 42, and the conductive material 43 that form the positive electrode 40 and the electrolytic solution included in the separator 60. The first coating 44 covers the entire surface of the positive electrode 40.

  Here, the surface of the positive electrode 40 is the entire surface of the positive electrode current collector 41, the positive electrode active material 42, and the conductive material 43 excluding the contact surfaces that contact each other. In other words, the surface of the positive electrode 40 is the surface where the positive electrode current collector 41, the positive electrode active material 42, and the conductive material 43 are exposed in the state where the first coating film 44 is not provided on the positive electrode 40.

  Similarly, the second coating 53 is a film that plays a role of suppressing the reaction between the negative electrode current collector 51 and the negative electrode active material 52 that form the negative electrode 50 and the electrolytic solution. The second coating 53 covers the entire surface of the negative electrode 50. The surface of the negative electrode 50 is defined similarly to the surface of the positive electrode 40.

  The negative electrode 50 may include the conductive material 43 forming the positive electrode 40. When the negative electrode 50 includes the conductive material 43, the second coating 53 covers the entire surface of the negative electrode 50 while ensuring conductivity inside the negative electrode 50.

Each of the coatings 44 and 53 is made of metal oxide. As one example, the metal oxide is an oxide containing at least one of Al, Ti, and Si. For example, it is an oxide containing at least one of Al ₂ O ₅ , TiO ₂ , and SiO ₂ .

Further, as another example, the metal oxide is an oxide containing at least Al and at least one of Ti and Si. For example, it is an oxide containing Al ₂ O ₅ , TiO ₂ , and SiO ₂ in the same layer.

As still another example, the metal oxide is an oxide containing Li. For example, LiAlO ₄ , Li ₄ Ti ₅ O ₁₂ , and LiSiO ₄ .

  In the present embodiment, the first coating 44 and the second coating 53 are made of the same metal oxide. In addition, in the configuration of the electricity storage device 1 according to the present embodiment, the first coating 44 and the second coating 53 may be configured by different metal oxides.

  The separator 60 plays a role of electrically insulating and separating the positive electrode 40 and the negative electrode 50 and holding an electrolytic solution. The separator 60 is sandwiched between the positive electrode 40 and the negative electrode 50. That is, the separator 60 is in contact with the first coating film 44 provided on the positive electrode 40 and the second coating film 53 provided on the negative electrode 50. Here, the portion of the first coating 44 that contacts the separator 60 is limited to the portion that covers the positive electrode active material 42 and the conductive material 43. Further, the portion of the second coating 53 that contacts the separator 60 is limited to the portion that covers the negative electrode active material 52.

  Further, the separator 60 has metal ion conductivity. That is, the separator 60 has a property of allowing electrons to pass therethrough but allowing metal ions to pass therethrough. As the separator 60, a porous synthetic resin film such as polyethylene or polypropylene is used. The separator 60 is configured to include an electrolytic solution (not shown). The electrolytic solution is also provided in the gap between the separator 60 and the positive electrode 40 and the gap between the separator 60 and the negative electrode 50. The separator 60 may include ceramic particles on the surface and inside. The above is the overall configuration of the electricity storage device 1 according to the present embodiment.

  Next, a method for manufacturing the storage element 1 will be described with reference to FIG. First, the positive electrode 40 and the negative electrode 50 are prepared. Since the method of forming the positive electrode 40 and the negative electrode 50 is the same, the step of preparing the positive electrode 40 will be described as an example.

  First, a compounding / mixing step of mixing and kneading the positive electrode mixture material including the positive electrode active material 42, the conductive material 43, and the binder in a solvent is performed. Subsequently, a coating step of applying a paste-like positive electrode mixture material to both surfaces of the positive electrode current collector 41 is performed, and a pressing step for adjusting the density of the positive electrode mixture material is performed. The positive electrode 40 after the pressing process is often wound into a roll, but this is not the case. In addition, a vacuum drying process may be performed in a decompression chamber for the purpose of removing water and solvent in the positive electrode 40.

  After that, a film forming step of forming the first film 44 is performed. The film formation is performed using an atomic layer deposition method (Atomic Layer Deposition; ALD). In the ALD method, for example, by adsorbing water on the surface of the positive electrode 40 and then flowing a raw material gas, a surface reaction between the water adsorbed on the surface of the positive electrode 40 and the raw material forms a very thin film on the surface of the positive electrode 40. Is the way to do it. In the ALD method, film formation is performed with 4 steps as one cycle.

  In order to form the first coating film 44 on the entire electrode surface of the positive electrode 40, the positive electrode 40 is installed in the chamber. The positive electrode 40 installed in the chamber may be in the form of a roll, may be cut into battery cell sizes, or may be in a state in which a plurality of sets thereof are present.

Then, the temperature inside the chamber is set to 100 ° C., the raw material TMA (trimethylaluminum) is set to 15 ° C., and the water (H ₂ O) is set to 25 ° C. to form the first coating film 44. As film forming conditions, TMA gas transportation was 0.3 sec, purging was 0.9 sec, H ₂ O gas transportation was 0.3 sec, and purging was 0.9 sec.

  Since the film forming temperature is low, it is preferable to set each film forming condition sufficiently large in consideration of gas viscosity. The inventors have also confirmed that the positive electrode active material 42 and the conductive material 43 are uniformly deposited on the entire surface with a film thickness proportional to the number of cycles.

For example, Al ₂ O ₃ is formed as the first coating film 44. Of course, if an ALD film that can be formed at 100 ° C. or lower and has an insulating property such as TiO ₂ , SiO ₂ , Ta ₂ O ₅ or the like can be formed, an ALD film of another metal oxide is formed. May be.

  Then, a cutting step of cutting the positive electrode current collector 41 into a cell shape is performed. Here, the first coating film 44 may be formed after the positive electrode current collector 41 is cut into a cell shape. That is, the cutting step is performed after the vacuum drying step. Then, a film forming step is performed after the cutting step. Accordingly, the first coating film 44 can be formed on the cut surface of the positive electrode current collector 41. For this reason, it is possible to secure the insulating property against the foreign metal particles mixed in the housing 10 and the insulating property such as the metal burr of the positive electrode current collector 41. Therefore, the quality of the storage element 1 is improved. The positive electrode 40 and the negative electrode 50 are formed as described above.

  Subsequently, a separator 60 is prepared, and an electrode assembly step of sandwiching the separator 60 between the positive electrode 40 and the negative electrode 50 is performed. That is, the laminated body 70 is formed by laminating the negative electrode 50, the separator 60, the positive electrode 40, the separator 60, the negative electrode 50, ...

  Further, the ends of the positive electrode collectors 41 of the plurality of positive electrodes 40 are connected to one end of the positive electrode terminal 20. Similarly, the ends of the negative electrode current collectors 51 of the plurality of negative electrodes 50 are connected to one end of the negative electrode terminal 30.

  After that, a cell assembling step of assembling the laminated body 70 to the housing 10 is performed. That is, the separator 60, the positive electrode 40, the negative electrode 50, part of the positive electrode terminal 20, and part of the negative electrode terminal 30 are housed in the housing chamber 18. Here, the laminated films 11 and 12 are joined so that one side of the outer peripheral edges 15 of the four sides of the laminated films 11 and 12 that form the housing 10 is open. Then, a vacuum drying process is performed in the decompression chamber.

  Further, an electrolytic solution injecting step of injecting an electrolytic solution through the openings of the laminate films 11 and 12 is performed. Finally, a sealing step of sealing the openings of the laminated films 11 and 12 is performed. In this way, the storage element 1 is completed.

  As described above, in the present embodiment, the first coating film 44 of metal oxide that covers the entire surface of the positive electrode 40 is provided. In such a configuration, the contact between the positive electrode current collector 41 and the positive electrode active material 42, the contact between the positive electrode current collector 41 and the conductive material 43, and the contact between the positive electrode active material 42 and the conductive material 43 are maintained. Thus, the first coating film 44 is formed on the surface of the positive electrode 40.

  Therefore, the electrical connection of each contact can be reliably ensured. That is, the electron conductivity of the positive electrode active material 42 can be ensured. On the other hand, in the positive electrode 40 configured by covering the positive electrode active material 42 and the like in advance with the coating, the positive electrode active material 42 and the positive electrode current collector 41 contact each other through the coating, and the positive electrode active material 42 and The conductive material 43 contacts. Therefore, the coating film becomes insufficient in electrical connection and becomes a resistance component. However, since the first coating film 44 according to the present embodiment does not hinder the electrical connection between the positive electrode current collector 41, the positive electrode active material 42, and the conductive material 43, it suppresses an increase in the resistance component in the mutual current paths. You can

  Further, since the positive electrode current collector 41, the positive electrode active material 42, and the conductive material 43 are covered with the first coating film 44, it is possible to prevent them from coming into contact with the electrolytic solution. Therefore, it is possible to suppress the generation of the electrolytic solution decomposition product in the reaction of the positive electrode current collector 41, the positive electrode active material 42, and the conductive material 43 with the electrolytic substance contained in the electrolytic solution. Therefore, the battery performance of the storage element 1 can be improved. With respect to the negative electrode 50 as well, the same effect as above can be obtained with the same configuration as the positive electrode 40.

  The inventors investigated the relationship between the thickness of the first coating 44 and the second coating 53 and the battery capacity of the storage element 1. The results are shown in FIGS. 5 and 6.

  First, when the battery capacity of the storage element 1 is increased or decreased from 0% to 100%, the potential on the surface of the positive electrode 40 rises. Therefore, in the case where the first coating film 44 is not formed, the positive electrode 40 and the electrolytic solution are likely to react with each other, and the electrolytic solution is decomposed to reduce the battery capacity. Therefore, the inventors examined the change in the capacity retention ratio of the electricity storage device 1 with respect to the increase in the number of cycles, with one charge / discharge of the electricity storage device 1 as one cycle.

Here, the positive electrode active material 42 to be investigated was LiNi _0.5 Mn _1.5 O ₄ and the negative electrode active material 52 was carbon (C). In the positive electrode 40, the positive electrode active material 42, the conductive material 43, and the binder that holds the positive electrode active material 42 and the conductive material 43 in the positive electrode terminal 41 were mixed at a ratio of 80:10:10. In the negative electrode 50, carbon (C) and the binder were mixed at a ratio of 90:10.

  As shown in FIG. 5, in the electricity storage device 1 in which the coating films 44 and 53 were not provided, the capacity retention ratio decreased as the number of cycles increased. On the other hand, in the storage element 1 provided with the coatings 44 and 53, the capacity retention rate was maintained regardless of the increase in the number of cycles.

  Further, FIG. 6 shows a discharge curve of the storage element 1 with and without the coatings 44 and 53. It was clarified that the capacities per active material differ depending on the presence or absence of the coatings 44 and 53. The main cause of the difference in the capacity per active material is the voltage drop immediately after discharge. In the case of no coating, the resistance increases due to the decomposition product of the electrolytic solution formed on the electrode surface. On the other hand, it is considered that the formation of the coating films 44 and 53 on the electrode surface can suppress the decomposition of the electrolytic solution and suppress the increase in resistance due to the decomposition of the electrolytic solution.

  From the above results, it can be seen that the coating films 44 and 53 improve the battery performance of the electricity storage device 1.

In particular, when the positive electrode active material 42 has an operating potential of 4.0 V or higher, the effect is particularly great. For example, in the electricity storage device 1 in which the positive electrode active material 42 is composed of a plurality of substances, such as containing at least one kind of substance of LiNi _0.5 Mn _1.5 O ₄ , LiMnPO _4, and LiCoPO ₄ , decomposition of the electrolytic solution is performed. Is easily promoted, the effect of forming the coating films 44 and 53 is great. Also, as referred LiFe _x Mn _1-x PO ₄ where part of the elements is substituted in LiMnPO _4, the same effect can be obtained for the electricity storage device 1 element with a positive electrode active material 42 which is partially substituted .

(Second embodiment)
In the present embodiment, parts different from the first embodiment will be described. As shown in FIG. 7, the electricity storage device 1 includes a third coating 71. The third coating 71 is a metal oxide film that covers the entire surface of the separator 60, the positive electrode 40, and the negative electrode 50 when the separator 60 is sandwiched between the positive electrode 40 and the negative electrode 50.

  That is, the third coating 71 is also formed on the surface of the separator 60 excluding the portions in contact with the positive electrode 40 and the negative electrode 50. Therefore, the positive electrode 40 and the negative electrode 50 are in direct contact with the separator 60, not via the third coating film 71. Further, the third coating 71 is formed of the same metal oxide on all of the positive electrode 40, the negative electrode 50, and the separator 60.

  Next, a method for manufacturing the electricity storage device 1 according to the present embodiment will be described with reference to FIG. In the present embodiment, a film forming step of forming the third coating film 71 is performed after the electrode assembly step of sandwiching the separator 60 between the positive electrode 40 and the negative electrode 50. That is, the third coating 71 is formed on the entire surface of the laminated body 70. The film formation may be performed in a state where a plurality of laminated bodies 70 are arranged in the chamber.

Then, the temperature inside the chamber is set to 60 ° C., the raw material TMA is set to 20 ° C., the water is set to 40 ° C., and the third coating film 71 of Al ₂ O _{3 is} formed as a metal oxide. Film forming conditions were as follows: TMA gas transportation was 1 sec, purging was 3 sec, H ₂ O gas transportation was 1 sec, and purging was 3 sec. The inventors have confirmed that the third coating film 71 is uniformly deposited on the entire surface of the laminated body 70.

Note that the outermost surface of the laminated body 70 can prevent the dissolution of the third coating film 71 by considering the dissolution of the third coating film 71 and having a laminated structure of, for example, Al ₂ O ₃ and TiO ₂ . Further, since the film forming temperature is low, it is preferable to set each film forming condition (particularly, the purge time) sufficiently large in consideration of a gas such as H ₂ O having a high viscosity.

  After forming the third coating 71 as described above, the respective steps after the cell assembling step described above are performed. Thus, the electricity storage device 1 according to the present embodiment is completed.

  As described above, by performing the step of forming the third coating film 71 after the electrode assembly step, it is possible to provide a configuration in which the third coating film 71 is provided on the entire laminated body 70 including the separator 60. Regarding the correspondence relationship between the description of the present embodiment and the description of the claims, the third coating 71 corresponds to the “coating” of the claims.

(Third Embodiment)
In this embodiment, parts different from the 22nd embodiment will be described. In the present embodiment, the third coating 71 is also formed inside the storage chamber 18 in which the stacked body 70 is stored. That is, the third coating 71 is a surface of the housing chamber 18 that is formed by the wall surface 19 of the housing chamber 18, the separator 60, the positive electrode 40, the negative electrode 50, a part of the positive electrode terminal 20, and a part of the negative electrode terminal 30. Covers the whole.

  Specifically, as shown in FIG. 9, the third coating 71 is formed on one end side which is a part of the positive electrode terminal 20, the wall surface 19 of the housing chamber 18, and the tab film 16 which constitutes the wall surface 19. It is a film. Therefore, the third coating 71 is formed of the same metal oxide on all of the wall surface 19 of the housing chamber 18, the separator 60, the positive electrode 40, the negative electrode 50, a part of the positive electrode terminal 20, and a part of the negative electrode terminal 30. There is.

  In addition, on the negative electrode terminal 30 side not shown, similarly, the third coating 71 is formed on one end side which is a part of the negative electrode terminal 30, the wall surface 19 of the housing chamber 18, and the tab film 17 constituting the wall surface 19. It is a film.

  Next, a method for manufacturing the electricity storage device 1 according to the present embodiment will be described with reference to FIG. 10. In this embodiment, first, a cell assembling step of assembling the laminated body 70 to the housing 10 as described above is performed. That is, the stacked body 70, part of the positive electrode terminal 20, and part of the negative electrode terminal 30 are housed in the housing chamber 18. In this step, one side of the outer peripheral edges 15 of the four sides of each of the laminate films 11 and 12 forming the housing 10 is opened. Then, a vacuum drying process is performed.

  After that, before forming the third coating 71, a mask is formed on the other end sides of the positive electrode terminal 20 and the negative electrode terminal 30 and on the outer surface of the housing 10. This prevents film formation on the other end sides of the positive electrode terminal 20 and the negative electrode terminal 30 and on the outer surface of the housing 10.

Then, a film forming process is performed in which the source gas is flown into the accommodation chamber 18 through the openings of the laminate films 11 and 12. The conditions for film formation are the same as in the second embodiment. As a result, the entire surface formed by the wall surface 19 of the storage chamber 18, the separator 60, the positive electrode 40, the negative electrode 50, a part of the positive electrode terminal 20, and a part of the negative electrode terminal 30 is Al ₂ O ₃ as a metal oxide. To form the third coating 71.

The film formation of the third coating 71 may be performed in a state where the plurality of housings 10 are arranged in the chamber. Further, similarly to the second embodiment, the outermost surface of the laminated body 70 may have a laminated structure of Al ₂ O ₃ and TiO ₂ .

  After forming the third coating 71 as described above, the above-described electrolytic solution injection step and the subsequent steps are performed. Thus, the electricity storage device 1 according to the present embodiment is completed. As described above, the step of forming the third coating 71 is formed after the vacuum drying step after the cell assembling step, so that the wall 19 of the housing chamber 18 of the housing 10 is also provided with the third coating 71. A configuration can be provided.

Further, in a lithium battery, lithium hexafluorophosphate (LiPF ₆ ) and lithium tetrafluoroborate (LiBF ₄ ) are often used as the salt of the electrolytic solution, but a protective film is not formed on the aluminum of the positive electrode current collector foil. For salts, specifically, lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), lithium bis (fluorosulfonyl) imide (LiFSI), etc., the third coating 71 of metal oxide is provided in the housing 10 of the electricity storage device 1. By forming the film, contact between aluminum and the electrolytic solution can be suppressed, and thus the same effect can be obtained.

  Regarding the correspondence relationship between the description of the present embodiment and the description of the claims, the third coating 71 corresponds to the “coating” of the claims.

(Other embodiments)
The configuration of the electricity storage device 1 shown in each of the above-described embodiments is an example, and the present invention is not limited to the configuration shown above, and may have another configuration that can realize the present invention. For example, the form of the electricity storage device 1 is not limited to the laminate type. For example, the electricity storage device 1 may have various shapes such as a coin shape, a cylinder shape, and a square shape.

  In addition, in each of the above-described embodiments, the content in which the positive electrode active material 42, the conductive material 43, the binder, and the like are used for the positive electrode 40 has been described. Is obtained.

  Furthermore, when LiFSI was used as the salt of the electrolytic solution, the same examination was carried out. As a result, the films with the films 44, 53 and 71 formed can maintain high battery performance as compared with the case without film formation. It became clear.

10 Casing 18 Storage Chamber 19 Wall Surface 20, 30 Terminal 40 Positive Electrode 42 Positive Electrode Active Material 44, 53, 71 Coating 50 Negative Electrode 52 Negative Electrode Active Material 60 Separator

Claims (8)

A positive electrode (40) containing, as a main component, a positive electrode active material (42) capable of inserting and extracting metal ions;
A negative electrode (50) containing as a main component a negative electrode active material (52) capable of inserting and extracting the metal ions;
A separator (60) sandwiched between the positive electrode and the negative electrode, having conductivity of the metal ions, and electrically insulating and separating the positive electrode and the negative electrode;
A positive electrode terminal (20) connected to the positive electrode,
A negative electrode terminal (30) connected to the negative electrode,
A housing for accommodating the separator, the positive electrode, the negative electrode, a part of the positive electrode terminal, and a part of the negative electrode terminal in the accommodating chamber (18) while the separator is sandwiched between the positive electrode and the negative electrode. (10),
A metal oxide covering the entire surface of the storage chamber, which is constituted by the wall surface (19) of the storage chamber, the separator, the positive electrode, the negative electrode, a part of the positive electrode terminal, and a part of the negative electrode terminal. Film (71) of
An electric storage device including. The electricity storage device according to claim 1, wherein the metal oxide is an oxide containing at least one of Al, Ti, and Si. The electricity storage device according to claim 1, wherein the metal oxide is an oxide containing at least Al and at least one of Ti and Si. The metal oxide, the electric storage device according to to any one of 3 claims 1 to an oxide containing Li. A step of preparing a positive electrode (40) whose main component is a positive electrode active material (42) capable of inserting and extracting metal ions;
A step of preparing a negative electrode (50) containing a negative electrode active material (52) capable of inserting and extracting metal ions as a main component;
A step of preparing a separator (60) having electrical conductivity of the metal ions and electrically insulating and separating the positive electrode and the negative electrode, and sandwiching the separator between the positive electrode and the negative electrode,
Connecting a positive electrode terminal (20) to the positive electrode,
Connecting a negative electrode terminal (30) to the negative electrode;
Preparing a casing (10) having a storage chamber (18) and storing the separator, the positive electrode, the negative electrode, a part of the positive electrode terminal, and a part of the negative electrode terminal in the storage chamber;
A metal oxide covering the entire surface of the storage chamber, which is constituted by the wall surface (19) of the storage chamber, the separator, the positive electrode, the negative electrode, a part of the positive electrode terminal, and a part of the negative electrode terminal. Forming a film (71) of
A method for manufacturing an electricity storage device including: The method of manufacturing an electricity storage device according to claim 5 , wherein in the step of forming the coating film, a coating film of an oxide containing at least one of Al, Ti, and Si is formed as the metal oxide. The method for manufacturing an electricity storage device according to claim 5 , wherein, in the step of forming the coating film, a coating film of an oxide containing at least Al as the metal oxide and containing at least one of Ti and Si is formed. In the step of forming the coating film, as the metal oxide, a manufacturing method of a power storage device according to any one of claims 5 to 7 to form a coating of oxide containing Li.

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