Electrochemical element, method for manufacturing the same, and module of the electrochemical element

Abstract

Provided is an electrochemical element with excellent reliability, a method for manufacturing the same, and a module of the electrochemical element.　This electrochemical element is characterized by comprising an exterior body and an electrode layered body sealed within the exterior body, and characterized in that: the electrode layered body includes a first electrode, a second electrode, and an isolation layer interposed between the first electrode and the second electrode; a resin foam sheet is disposed between the electrode layered body and the exterior body; and the electrode layered body is pressed by the foam sheet. This electrochemical element module is characterized by being configured so that: the electrochemical element module accommodates, in a casing, a layered body in which a plurality of the electrochemical elements are layered; and so that the exterior body of each electrochemical element is constituted by a laminate film.

Description

Technical Field

[0001] The present invention relates to an electrochemical element having excellent reliability, a method for manufacturing the same, and a module of the electrochemical element.

Background Art

[0002] In recent years, with the development of portable electronic devices such as mobile phones and notebook personal computers, and the practical application of electric vehicles, there has been an increasing need for batteries that are small, lightweight, and have high capacity and high energy density.

[0003] Currently, in lithium batteries, particularly lithium ion batteries, which can meet this requirement, an organic electrolyte solution containing an organic solvent and a lithium salt is used as a non-aqueous electrolyte.

[0004] With the further development of the devices to which lithium ion batteries are applied, there is a demand for further extending the lifespan, increasing the capacity, and increasing the energy density of lithium ion batteries. At the same time, high reliability of lithium ion batteries with extended lifespan, increased capacity, and increased energy density is also highly demanded.

[0005] However, since the organic electrolyte solution used in lithium ion batteries contains an organic solvent, which is a flammable substance, when an abnormal situation such as a short circuit occurs in the battery, the organic electrolyte solution may generate abnormal heat. In addition, with the increasing energy density of recent lithium ion batteries and the increasing trend of the amount of organic solvent in the organic electrolyte solution, the reliability of lithium ion batteries is further demanded.

[0006] Under the above circumstances, all-solid-state lithium batteries (all-solid batteries) that do not use organic solvents have attracted attention. An all-solid battery uses a molded body of a solid electrolyte that does not use an organic solvent instead of a conventional organic solvent-based electrolyte, and has no risk of abnormal heat generation of the solid electrolyte and has high safety.

[0007] In addition, all-solid-state batteries are expected to be maintenance-free batteries that not only have high safety but also high reliability, high environmental resistance, and long life, and thus can contribute to the development of society while continuously contributing to peace of mind and safety. By providing all-solid-state batteries to society, among the 17 goals of the Sustainable Development Goals (SDGs) established by the United Nations, it is possible to contribute to the achievement of Goal 3 (Ensure healthy lives and promote well-being for all people of all ages), Goal 7 (Ensure access for all people to affordable, reliable, and sustainable modern energy), Goal 11 (Make cities and human settlements inclusive, safe, resilient, and sustainable), and Goal 12 (Ensure sustainable consumption and production patterns).

[0008] By the way, various exterior bodies are used in batteries such as all-solid-state batteries. For example, in Patent Document 1, there is an insulating substrate having a recess for accommodating a power generation element and having two external electrodes on the bottom surface, and a lid body for closing the recess. A conductive sheet considered to function as a current collector is disposed above and below the power generation element, and wiring for electrically connecting one of the conductive sheets to one of the two external electrodes and wiring for electrically connecting the other of the conductive sheets to the remaining one of the two external electrodes are provided. A battery package is proposed.

[0009] And Patent Document 1 describes that an elastic body (spacer) such as rubber is interposed between the lid body and the conductive sheet, and the thickness of the spacer is made thicker than the interval between the lid body and the conductive sheet, so that the conductive sheet is pressed against the electrode of the power generation element by the elastic force of the spacer to perform conductive connection and fixation of the battery (electrode body). It is also described that a thermally expandable butyl rubber or the like is used as the spacer, and after the exterior body is sealed, the butyl rubber or the like is thermally expanded to cause the same action as described above.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

[0011] However, in the method using elastic materials such as rubber, it is necessary to press the spacer with the lid to reduce the thickness of the spacer when sealing the outer casing, which can easily lead to a decrease in sealing performance. In addition, in the method using thermally expandable butyl rubber, it is necessary to heat the butyl rubber to a high temperature (200°C or higher) where thermal expansion is possible, which raised concerns about a decrease in battery performance due to the deterioration of the active material and solid electrolyte.

[0012] The present invention has been made in view of the above circumstances, and its object is to provide an electrochemical element with excellent reliability, a method for manufacturing the same, and a module of the electrochemical element. [Means for solving the problem]

[0013] The electrochemical element of the present invention comprises an outer casing and an electrode laminate sealed inside the outer casing, wherein the electrode laminate has a first electrode, a second electrode, and an isolation layer interposed between the first electrode and the second electrode, and a resin foam sheet is disposed between the electrode laminate and the outer casing, and the electrode laminate is pressed by the foam sheet.

[0014] The electrochemical element module of the present invention is characterized in that a laminate formed by stacking multiple electrochemical elements of the present invention is housed in a housing, and the outer casing of the electrochemical element is made of a laminate film.

[0015] The electrochemical element of the present invention can be manufactured by a manufacturing method of the present invention, which is characterized by comprising a sealing step of sealing an electrode laminate having a first electrode, a second electrode, and an isolation layer interposed between the first electrode and the second electrode, and a resin sheet that foams and expands when heated, within an outer casing, and a heating step of heating the resin sheet to cause it to foam and pressing the electrode laminate with the expanded resin sheet. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an electrochemical element with excellent reliability, a method for manufacturing the same, and a module of the electrochemical element. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic cross-sectional view showing an example of the electrochemical element of the present invention. [Figure 2] This is a schematic cross-sectional view showing a different example of the electrochemical element of the present invention from Figure 1. [Figure 3] Figure 2 is a schematic cross-sectional view of an electrochemical element module in which multiple electrochemical elements shown are stacked and incorporated into a housing. [Modes for carrying out the invention]

[0018] Figure 1 shows a schematic longitudinal cross-sectional view of an example of the electrochemical element of the present invention. The electrochemical element 100 shown in Figure 1 has an electrode stack 110 having a first electrode 111, a second electrode 112, and an isolation layer 113 interposed between them, and this electrode stack 110 is enclosed within an outer casing formed by an outer container 140 and a lid 150.

[0019] External terminals 160 and 170 are provided on the lower surface of the outer container 140 in the figure for electrically connecting to equipment to which the electrochemical element 100 is applied. External terminal 160 is electrically connected to a current collector 120 located on the outside of the first electrode 111 in the electrode stack 110 (opposite side from the isolation layer 113) via a conductive path 161. Furthermore, external terminal 170 is electrically connected to a current collector 121 located on the outside of the second electrode 112 in the electrode stack 110 (opposite side from the isolation layer 113) via a conductive path 171.

[0020] Furthermore, a resin foam sheet 130 is placed on the opposite side (upper side in the figure) of the current collector 121, which is positioned outside the second electrode 112 in the electrode stack 110, from the second electrode 112. Due to the expansion force of the foam sheet 130, the current collector 121 and the electrode stack 110 via the current collector 121 are pressed downward in the figure. As a result, the position of the electrode stack 110 is fixed, and good conductivity is maintained between the current collector 121, the second electrode 112, and the conductive path 171.

[0021] If the electrode stack 110 has a solid electrolyte layer as an isolation layer 113, for example, only the electrode stack 110 is sealed inside the outer casing. On the other hand, if the electrode stack 110 has a separator as an isolation layer 113, an electrolyte (not shown) is sealed inside the outer casing along with the electrode stack 110.

[0022] As shown in Figure 1, in the electrochemical element of the present invention, a resin foam sheet may be placed on one side of an electrode laminate having a first electrode, a second electrode, and an isolation layer interposed between the first electrode and the second electrode, or resin foam sheets may be placed on both sides of the electrode laminate.

[0023] The aforementioned foamed resin sheet expands and foams upon heating, and can be formed by using a resin sheet of a thickness that does not interfere with the sealing process of the outer casing, and by heating the resin sheet under appropriate conditions that do not affect the properties of the active material or solid electrolyte after the outer casing has been sealed. Therefore, since the electrochemical element can be assembled without degrading the sealing performance or properties, a highly reliable electrochemical element can be obtained.

[0024] In the electrochemical element 100 shown in Figure 1, a resin foam sheet 130 is placed on the side of the current collector 121, which is located outside the second electrode 112 of the electrode stack 110, that is opposite to the second electrode 112. However, no foam sheet is placed on the side of the current collector 120, which is located outside the first electrode 111. Nevertheless, the foam sheet 130 presses the electrode stack 110 downwards in the figure via the current collector 121, causing the first electrode 111 to be pressed against the current collector 120. As a result, in the electrochemical element 100 shown in Figure 1, the position of the electrode stack 110 is fixed by the action of the resin foam sheet 130, preventing displacement due to vibration, etc., and good conductivity is maintained not only between the second electrode 112 and the current collector 121 and between the current collector 121 and the conductive path 171, but also between the first electrode 111 and the current collector 120 and between the current collector 120 and the conductive path 161.

[0025] Depending on the arrangement and shape of the conductive path 161 connecting the first electrode 111 and the external terminal 160 in the figure, it is also possible to place a resin foam sheet on the opposite side (lower side in the figure) of the current collector 120, which is located outside the first electrode 111 related to the electrode laminate 110, to press the current collector 120 against the first electrode 111.

[0026] Figure 2 shows a schematic cross-sectional view illustrating another example of the electrochemical element of the present invention. The electrochemical element 200 shown in Figure 2 is an example having an outer casing 210 made of a laminate film. The electrochemical element 200 has an electrode laminate 110 formed by laminating a first electrode 111 having a first electrode active material layer 111a containing an active material and a first electrode current collector 111b, and a second electrode 112 having a second electrode active material layer 112a containing an active material and a second electrode current collector 112b, with an isolation layer 113 in between.

[0027] In the electrochemical element 200 shown in Figure 2, similar to the electrochemical element 100 shown in Figure 1, if the electrode stack 110 has a solid electrolyte layer as an isolation layer 113, for example only the electrode stack 110 is sealed inside the outer casing 210, and if the electrode stack 110 has a separator as an isolation layer 113, the outer casing 210 contains the electrode stack 110 along with an electrolyte (not shown).

[0028] In the first electrode 111 of the electrochemical element 200, the first electrode current collector 111b is provided with an exposed portion that does not come into contact with the first electrode active material layer 111a. This exposed portion is brought out to the outside of the outer casing 210 and forms a terminal portion 111c for electrically connecting the electrochemical element 200 to the application equipment or for electrically connecting the first electrodes of the electrochemical elements when forming an electrochemical element module (described later). The terminal portion 111c of the first electrode may be formed by using a separate conductive material (metal, carbon, etc.) foil, plate, wire, etc., and connecting it to the first electrode current collector 111b.

[0029] Furthermore, although not shown in Figure 2, the second electrode 112 also has an exposed portion on the second electrode current collector 112b that does not come into contact with the second electrode active material layer 112a. This exposed portion is brought out to the outside of the outer casing 210 and forms a terminal portion for electrically connecting the electrochemical element 200 to the application equipment or for electrically connecting the second electrodes of the electrochemical elements when forming an electrochemical element module (described later). The terminal portion of the second electrode may also be formed by using a separate conductive material (metal, carbon, etc.) foil, plate, or wire, and connecting it to the second electrode current collector 112b.

[0030] Furthermore, resin foam sheets 130, 130 are placed between the outer casing 210 and the electrode stack 110 (above and below the electrode stack 110 in Figure 2). In the electrode stack 200 shown in Figure 2, the resin foam sheets 130, 130 prevent misalignment between the components constituting the electrode stack 110 and enhance the conductivity or ionic conductivity between the components.

[0031] The electrochemical elements of the present invention include batteries and capacitors. Furthermore, when the electrochemical element of the present invention is a battery, it includes primary batteries and secondary batteries, as well as batteries having a solid electrolyte layer interposed between a positive electrode and a negative electrode (all-solid-state batteries), and batteries having a separator interposed between a positive electrode and a negative electrode and an electrolyte containing a solvent (electrolyte solution or gel-like electrolyte) (batteries other than all-solid-state batteries). In addition, when the electrochemical element of the present invention is a capacitor, it includes electric double-layer capacitors, lithium-ion capacitors, and the like.

[0032] <Resin foam sheet> In the electrochemical element, the foamed resin sheet can be formed by using a resin sheet that can foam and expand at a temperature of 195°C or lower during the assembly of the electrochemical element, and by heating the resin sheet after sealing the outer casing to cause it to foam and expand. The minimum temperature at which foaming begins for the foamable resin sheet is preferably 60°C or higher, from the viewpoint of suppressing unexpected foaming, for example, during the manufacturing of the electrochemical element. Furthermore, the heating of the resin sheet is actually performed by heating the sealed outer casing.

[0033] As resin sheets that can be foamed at temperatures below 195°C, various resins that do not easily degrade inside electrochemical elements, such as urethane resin, epoxy resin, and silicone resin, which contain a foaming agent, are preferably used.

[0034] Regarding the foaming agent, there are no particular restrictions as long as it does not impair the properties of the electrodes (active material) and the separator (separator or solid electrolyte layer) of the electrochemical element when the resin sheet is foamed, and can foam the resin sheet at or below the aforementioned temperature (and more preferably, cannot foam the resin sheet below the aforementioned minimum temperature). Conventional foaming agents such as urethane resin, epoxy resin, and silicone resin can be used. In addition, "Advancell EM (product name)" manufactured by Sekisui Chemical Co., Ltd. can also be used as a foaming agent.

[0035] Furthermore, commercially available products (such as Nikkan Industries' foam adhesive sheet "SAFB" (product name)) can be used for resin sheets that can be foamed at temperatures below 195°C.

[0036] The thickness of the foamable resin sheet used in assembling the electrochemical element before foaming is preferably 10 μm or more, and more preferably 20 μm or more, from the viewpoint of ensuring that the current collector is properly pressed against the electrode after foaming. However, if the foamable resin sheet is too thick, not only will the above-mentioned effect be saturated, but the volume occupied by components that do not participate in power generation within the electrochemical element will also increase. Therefore, the thickness of the foamable resin sheet is preferably 2000 μm or less, more preferably 500 μm or less, and particularly preferably 100 μm or less.

[0037] Furthermore, the thickness of the foamable resin sheet when foamed without being incorporated into an electrochemical element (the thickness when freely expanded) is preferably 1.1 times or more, more preferably 1.2 times or more, and particularly preferably 1.5 times or more, the thickness of the resin sheet before foaming, in order to ensure sufficient pressing force on the electrodes when foamed after being incorporated into an electrochemical element. The degree of change in the thickness of the resin sheet due to foaming can be adjusted, for example, by changing the amount of foaming agent contained in the resin sheet.

[0038] <Electrode Laminate> The electrode stack comprises a first electrode, a second electrode, and an isolation layer interposed between them.

[0039] Examples of the first and second electrodes include electrodes made of a molded body of an electrode mixture containing an electrode active material, and electrodes having this molded body as an electrode mixture layer.

[0040] When an electrochemical element using an electrode stack is a battery or a lithium-ion capacitor, one of the first electrode and the second electrode is the positive electrode and the other is the negative electrode. Furthermore, when an electrochemical element using an electrode stack is an electric double-layer capacitor, the first electrode and the second electrode can be electrodes with the same configuration.

[0041] When the electrochemical device is a battery and one of the first electrode and the second electrode is a positive electrode, the electrode mixture constituting this, that is, the positive electrode mixture, contains a positive electrode active material and the like.

[0042] When the electrode is the positive electrode of a primary battery, the same positive electrode active materials as those used in conventionally known non-aqueous electrolyte primary batteries, alkaline batteries, manganese batteries, etc. can be used. Specifically, for example, manganese dioxide, lithium-containing manganese oxides [for example, LiMn3O6 and composite oxides having the same crystal structure as manganese dioxide (such as β-type, γ-type, or a structure in which β-type and γ-type are mixed), and the content of Li is 3.5 mass% or less, preferably 2 mass% or less, more preferably 1.5 mass% or less, and particularly preferably 1 mass% or less], Li a Ti 5 / 3 Lithium-containing composite oxides such as O4 (4 / 3 ≤ a < 7 / 3); vanadium oxides; niobium oxides; titanium oxides; sulfides such as iron disulfide; graphite fluoride; silver sulfides such as Ag2S; nickel oxides such as NiO2; silver oxide, etc. can be mentioned.

[0043] Also, when the electrode is the positive electrode of a secondary battery, the positive electrode active materials used in conventionally known non-aqueous electrolyte secondary batteries and alkaline secondary batteries can be used. Specifically, Li 1-x M r Mn 2-r Spinel-type lithium manganese composite oxides represented by O4 (where M is at least one element selected from the group consisting of Li, Na, K, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Zr, Fe, Co, Ni, Cu, Zn, Al, Sn, Sb, In, Nb, Ta, Mo, W, Y, Ru, and Rh, 0 ≤ x ≤ 1, 0 ≤ r ≤ 1), Li r Mn (1-s-t) Ni s M t O (2-u) F v(However, M is at least one element selected from the group consisting of Co, Mg, Al, B, Ti, V, Cr, Fe, Cu, Zn, Zr, Mo, Sn, Ca, Sr, and W, 0 ≦ r ≦ 1.2, 0 < s < 0.5, 0 ≦ t ≦ 0.5, u + v < 1, -0.1 ≦ u ≦ 0.2, 0 ≦ v ≦ 0.1) layered compound, Li 1-x Co 1-r M r O2 (However, M is at least one element selected from the group consisting of Al, Mg, Ti, V, Cr, Zr, Fe, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, 0 ≦ x ≦ 1, 0 ≦ r ≦ 0.5) lithium cobalt composite oxide, Li 1-x Ni 1-r M r O2 (However, M is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Fe, Co, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, 0 ≦ x ≦ 1, 0 ≦ r ≦ 0.5) lithium nickel composite oxide, Li 1+s-x M 1-r N r PO4F s (However, M is at least one element selected from the group consisting of Fe, Mn, and Co, and N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, V, and Ba, 0 ≦ x ≦ 1, 0 ≦ r ≦ 0.5, 0 ≦ s ≦ 1) olivine-type composite oxide, Li 2-x M 1-r N r P2O7 (However, M is at least one element selected from the group consisting of Fe, Mn, and Co, and N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, V, and Ba, 0 ≦ x ≦ 2, 0 ≦ r ≦ 0.5) pyrophosphate compound, nickel hydroxide, silver oxide, etc. can be exemplified, and only one of these may be used, or two or more may be used in combination.

[0044] When the electrochemical element is an all-solid-state secondary battery, the average particle size of the positive electrode active material is preferably 1 μm or more, more preferably 2 μm or more, more preferably 10 μm or less, and more preferably 8 μm or less. The positive electrode active material may be primary particles or secondary particles formed by aggregation of primary particles. Using a positive electrode active material with an average particle size within the above range allows for a larger interface with the solid electrolyte contained in the positive electrode, thereby improving the output characteristics of the battery.

[0045] In this specification, the average particle diameter of various particles (such as positive electrode active material and solid electrolyte) is the 50% diameter value in the volume-based integrated fraction when determining the integrated volume from the smallest particles using a particle size distribution analyzer (such as the Microtrac particle size distribution analyzer "HRA9320" manufactured by Nikkiso Co., Ltd.). 50 ) means.

[0046] In the case of an all-solid-state secondary battery, it is preferable that the positive electrode active material has a reaction-inhibiting layer on its surface to suppress the reaction with the solid electrolyte contained in the positive electrode.

[0047] If the positive electrode active material and the solid electrolyte come into direct contact within the molded electrode mixture (the molded positive electrode mixture), the solid electrolyte may oxidize and form a resistive layer, potentially reducing the ionic conductivity within the molded electrode mixture. By providing a reaction-inhibiting layer on the surface of the positive electrode active material to suppress the reaction with the solid electrolyte, direct contact between the positive electrode active material and the solid electrolyte can be prevented, thereby suppressing the reduction in ionic conductivity within the molded electrode mixture due to oxidation of the solid electrolyte.

[0048] The reaction suppression layer should be composed of a material that has ionic conductivity and can suppress the reaction between the positive electrode active material and the solid electrolyte. Examples of materials that can constitute the reaction suppression layer include oxides containing Li and at least one element selected from the group consisting of Nb, P, B, Si, Ge, Ti, and Zr, more specifically, Nb-containing oxides such as LiNbO3, Li3PO4, Li3BO3, Li4SiO4, Li4GeO4, LiTiO3, LiZrO3, and Li2WO4. The reaction suppression layer may contain only one of these oxides, or two or more, and furthermore, multiple of these oxides may form a composite compound. Among these oxides, it is preferable to use an Nb-containing oxide, and more preferable to use LiNbO3.

[0049] The reaction-inhibiting layer is preferably present on the surface in an amount of 0.1 to 1.0 part by mass per 100 parts by mass of positive electrode active material. Within this range, the reaction between the positive electrode active material and the solid electrolyte can be effectively suppressed.

[0050] Methods for forming a reaction-inhibiting layer on the surface of the positive electrode active material include the sol-gel method, mechanofusion method, CVD method, PVD method, and ALD method.

[0051] From the viewpoint of increasing the energy density of the electrochemical element, the content of the positive electrode active material in the positive electrode mixture is preferably 60 to 85% by mass.

[0052] The positive electrode mixture may contain a conductive additive. Specific examples include carbon materials such as graphite (natural graphite, artificial graphite), graphene, carbon black, carbon nanofibers, and carbon nanotubes. However, if Ag2S is used as the active material, conductive Ag is generated during the discharge reaction, so a conductive additive does not need to be included. When a conductive additive is included in the positive electrode mixture, its content is preferably 1.0 part by mass or more, preferably 7.0 parts by mass or less, and more preferably 6.5 parts by mass or less, based on the content of 100 parts by mass of the positive electrode active material.

[0053] Furthermore, a binder can be included in the positive electrode mixture. Specific examples include fluororesins such as polyvinylidene fluoride (PVDF). However, if good moldability can be ensured in forming the molded body of the electrode mixture (the molded body of the positive electrode mixture) without using a binder, such as when the positive electrode mixture contains a sulfide-based solid electrolyte (details will be described later), then the positive electrode mixture does not need to contain a binder.

[0054] In the positive electrode mixture, if a binder is required, its content is preferably 15% by mass or less, and more preferably 0.5% by mass or more. On the other hand, in the positive electrode mixture, if moldability can be obtained without the need for a binder, its content is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0% by mass (i.e., no binder is included).

[0055] If the electrochemical element is an all-solid-state battery (all-solid-state primary battery, all-solid-state secondary battery), the positive electrode mixture must contain a solid electrolyte.

[0056] The solid electrolyte to be included in the positive electrode mixture is not particularly limited as long as it has lithium ion conductivity, and for example, sulfide-based solid electrolytes, hydride-based solid electrolytes, halide-based solid electrolytes, oxide-based solid electrolytes, etc., can be used.

[0057] Examples of sulfide-based solid electrolytes include particles such as Li2S-P2S5, Li2S-SiS2, Li2S-P2S5-GeS2, and Li2S-B2S3 glass, as well as thio-LISICON type electrolytes, which have recently attracted attention for their high Li ion conductivity. 10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 such as, immortal 12-12a-b+c+6d-e M 1 3+a-b-c-d M2 b M 3 c M 4 d M 5 12-e X e (However, M 1 is Si, Ge or Sn, M 2 is P or V, M 3 is Al, Ga, Y or Sb, M 4 is Zn, Ca, or Ba, M 5 is either S or S and O, X is F, Cl, Br or I, 0 ≦ a < 3, 0 ≦ b + c + d ≦ 3, 0 ≦ e ≦ 3), and those having an argyrodite-type crystal structure can also be used.

[0058] Examples of the hydride-based solid electrolyte include, for example, LiBH4, a solid solution of LiBH4 and the following alkali metal compound (for example, those having a molar ratio of LiBH4 to the alkali metal compound of 1:1 to 20:1). Examples of the alkali metal compound in the solid solution include at least one selected from the group consisting of lithium halide (LiI, LiBr, LiF, LiCl, etc.), rubidium halide (RbI, RbBr, RbF, RbCl, etc.), cesium halide (CsI, CsBr, CsF, CsCl, etc.), lithium amide, rubidium amide, and cesium amide.

[0059] Examples of the halide-based solid electrolyte include, for example, monoclinic LiAlCl4, defective spinel-type or layered LiInBr4, monoclinic Li 6-3m Y m X6 (where 0 < m < 2 and X = Cl or Br), etc., and in addition, for example, those known in International Publication No. 2020 / 070958 and International Publication No. 2020 / 070955 can also be used.

[0060] Examples of the oxide-based solid electrolyte include, for example, garnet-type Li7La3Zr2O 12 , NASICON-type Li 1+O Al 1+O Ti 2-O(PO4)3, Li 1+p Al 1+p Ge 2-p (PO4)3, perovskite-type Li 3q La 2 / 3-q Examples include TiO3.

[0061] Among these solid electrolytes, sulfide-based solid electrolytes are preferred due to their high lithium ion conductivity, sulfide-based solid electrolytes containing Li and P are more preferred, and sulfide-based solid electrolytes having an argyrodite crystal structure are even more preferred due to their higher lithium ion conductivity and chemical stability.

[0062] As sulfide-based solid electrolytes having an argyrodite-type crystal structure, those containing Li, P, S, and halogen elements, such as Li6PS5Cl, are particularly preferred.

[0063] The average particle size of the solid electrolyte is preferably 0.1 μm or larger, and more preferably 0.2 μm or larger, from the viewpoint of reducing grain boundary resistance. On the other hand, from the viewpoint of forming a sufficient contact interface between the active material and the solid electrolyte, it is preferably 10 μm or smaller, and more preferably 5 μm or smaller.

[0064] From the viewpoint of further enhancing ionic conductivity within the positive electrode and improving the output characteristics of the electrochemical element, the solid electrolyte content in the positive electrode mixture is preferably 10 parts by mass or more, and more preferably 15 parts by mass or more, when the positive electrode active material content is 100 parts by mass. However, if the amount of solid electrolyte in the positive electrode mixture is too high, the amount of other components will decrease, and the effects of those components may be reduced. Therefore, the solid electrolyte content in the positive electrode mixture is preferably 65 parts by mass or less, and more preferably 60 parts by mass or less, when the positive electrode active material content is 100 parts by mass.

[0065] When the electrochemical element is a battery, and one of the first and second electrodes is the negative electrode, the electrode mixture, i.e., the negative electrode mixture, contains a negative electrode active material, etc.

[0066] Examples of negative electrode active materials include carbon materials such as graphite, lithium titanium oxide (such as lithium titanate), elements such as Si and Sn, elements in elemental form, compounds (such as oxides), and alloys thereof. In addition, lithium metal and lithium alloys (such as lithium-aluminum alloy and lithium-indium alloy), zinc, and hydrogen storage alloys can also be used as negative electrode active materials.

[0067] From the viewpoint of increasing the energy density of the battery, the content of the negative electrode active material in the negative electrode mixture is preferably 40 to 80% by mass.

[0068] The negative electrode mixture may contain a conductive additive. Specific examples include the same conductive additives mentioned earlier as those that can be included in the positive electrode mixture. The content of the conductive additive in the negative electrode mixture is preferably 10 to 30 parts by mass, based on a negative electrode active material content of 100 parts by mass.

[0069] Furthermore, a binder can be included in the negative electrode mixture. Specific examples include the same binders mentioned earlier that can be included in the positive electrode mixture. However, if good moldability can be ensured when forming the molded body of the electrode mixture (the molded body of the negative electrode mixture) without using a binder, such as when the negative electrode mixture contains a sulfide-based solid electrolyte (as described later), then the negative electrode mixture does not need to contain a binder.

[0070] In the negative electrode mixture, if a binder is required, its content is preferably 15% by mass or less, and more preferably 0.5% by mass or more. On the other hand, in the negative electrode mixture, if moldability can be obtained without the need for a binder, its content is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0% by mass (i.e., no binder is included).

[0071] When the electrochemical element is an all-solid-state battery, the negative electrode mixture contains a solid electrolyte. Specific examples include the same solid electrolytes exemplified earlier that can be included in the positive electrode mixture. Among the exemplified solid electrolytes, sulfide-based solid electrolytes are preferred because they have high lithium-ion conductivity and enhance the moldability of the negative electrode mixture. More preferably, sulfide-based solid electrolytes having an argyrodite crystal structure are used, and even more preferably, those containing Li, P, S, and halogen elements, such as Li6PS5Cl, are preferred.

[0072] For the same reasons as in the case of the positive electrode mixture, the average particle size of the solid electrolyte is preferably 0.1 μm or larger, more preferably 0.2 μm or larger, and more preferably 10 μm or smaller, and more preferably 5 μm or smaller.

[0073] From the viewpoint of further enhancing ionic conductivity within the negative electrode and improving the output characteristics of the electrochemical element, the solid electrolyte content in the negative electrode mixture is preferably 30 parts by mass or more, and more preferably 35 parts by mass or more, when the negative electrode active material content is 100 parts by mass. However, if the amount of solid electrolyte in the negative electrode mixture is too high, the amount of other components will decrease, and the effects of those components may be reduced. Therefore, the solid electrolyte content in the negative electrode mixture is preferably 130 parts by mass or less, and more preferably 110 parts by mass or less, when the negative electrode active material content is 100 parts by mass.

[0074] Furthermore, if the electrochemical element is a battery, one of the first and second electrodes used as the negative electrode can also be a sheet of metal that functions as the negative electrode active material, such as a sheet of lithium or a sheet of lithium alloy.

[0075] When the electrochemical element using the electrode stack is an electric double-layer capacitor, the first and second electrodes may have molded bodies of electrode mixtures formed from electrode mixtures having a similar configuration to the positive electrode mixture described above, except that activated carbon is used as the active material.

[0076] Furthermore, when the electrochemical element using the electrode stack is a lithium-ion capacitor, one of the first and second electrodes can be used as the positive electrode with the same configuration as the first and second electrodes in an electric double-layer capacitor, and the other electrode can be used as the negative electrode with the same configuration as the negative electrode in a battery.

[0077] The thickness of the first electrode and the second electrode is preferably 50 to 3000 μm.

[0078] In an electrode stack, an isolation layer is interposed between the first electrode and the second electrode. However, in batteries and capacitors that do not use solvent-containing electrolytes, such as all-solid-state batteries, a solid electrolyte layer is used as the isolation layer.

[0079] Specific examples of the solid electrolyte constituting the solid electrolyte layer include the same solid electrolytes as those previously exemplified as those that can be included in the positive electrode mixture. Among the solid electrolytes exemplified above, sulfide-based solid electrolytes are preferred because they have high lithium ion conductivity and the function of improving moldability, sulfide-based solid electrolytes having an argyrodite-type crystal structure are preferred, and those represented by the general composition formula (1) or the general composition formula (2) are even more preferred.

[0080] The solid electrolyte layer may have a porous material, such as a resin nonwoven fabric, as a support.

[0081] The thickness of the solid electrolyte layer is preferably 10 to 200 μm.

[0082] In electrode stacks used in batteries and capacitors that utilize electrolytes containing solvents, a separator is used as an isolation layer between the first electrode and the second electrode.

[0083] As a separator, one that has sufficient strength and can retain a large amount of electrolyte is preferable. From this viewpoint, microporous films or nonwoven fabrics containing polyethylene, polypropylene, or ethylene-propylene copolymer, with a thickness of 10 to 50 μm and an opening ratio of 30 to 70%, are preferred.

[0084] An electrode laminate can be manufactured, for example, by using a first electrode and / or second electrode formed from a molded body of an electrode mixture obtained by pressure molding the electrode mixture, or by using a metal sheet that functions as a negative electrode active material as the first or second electrode, and laminating these to a separately molded solid electrolyte layer or separator. Alternatively, an electrode laminate can also be manufactured by, for example, putting a solid electrolyte constituting the solid electrolyte layer into a mold and pressure molding it to form a temporary molded body, putting an electrode mixture constituting the first electrode (or second electrode) into one side of this temporary molded body of the solid electrolyte and pressure molding to integrate the solid electrolyte and the temporary molded body of the first electrode (or second electrode), and then putting an electrode mixture constituting the second electrode (or first electrode) into the other side of the temporary molded body of the solid electrolyte and pressure molding to form the final electrode laminate.

[0085] Furthermore, when forming the first and second electrodes, a current collector can be placed on one side of the electrode mixture poured into the mold, and then pressure-molded to integrate the first and second electrodes with the current collector.

[0086] <Current collector> The current collector, which is positioned outside at least one of the first and second electrodes in the electrode stack, can be made of metal foil, perforated metal, mesh, expanded metal, foamed metal, carbon sheet, etc.

[0087] Among such current collectors, it is preferable to use a foamed porous metal material (such as "Cellmet®" manufactured by Sumitomo Electric Industries, Ltd.) because it offers higher current collection efficiency. The molded bodies of the electrode mixture for the first and second electrodes have relatively rough surfaces, and the current collector made of a foamed porous metal material also has a relatively rough surface. It is presumed that the pressing force of the foamed sheet causes a portion of its surface to penetrate inward from the surface of the molded body of the electrode mixture, thereby increasing the contact area.

[0088] The thickness of the current collector is preferably 50 to 1500 μm.

[0089] The current collector can be used without being integrated with the first or second electrode, but as mentioned above, it may also be used integrated with the first or second electrode.

[0090] <Exterior> For the casing of an electrochemical element, for example, a case consisting of an outer container and a lid, as shown in Figure 1, can be used. In such a casing, the outer container can be made of ceramics or resin. The lid can be made of ceramics, resin, or metal (such as iron-nickel alloys or iron-based alloys such as iron-nickel-cobalt alloys).

[0091] In the outer casing, the external terminals and the conductive paths connecting the electrodes in the electrode stack to the external terminals can be made of metals such as manganese, cobalt, nickel, copper, molybdenum, silver, palladium, tungsten, platinum, and gold, or alloys containing these metals.

[0092] The outer container and the lid can be sealed by bonding them together with adhesive. Alternatively, if a metal lid is used, the side wall of the recess in the outer container that faces the lid can be made of metal (such as an iron-nickel alloy or an iron-nickel-cobalt alloy), and then welded to the lid to seal it.

[0093] Furthermore, similar to conventional coin-type batteries, the outer casing and lid may be made of metal, and the outer casing and lid may be sealed by crimping them together with a gasket or by bonding them together with an adhesive.

[0094] Furthermore, the outer casing may be made of laminate film, as shown in Figure 2. The laminate film used to make up the outer casing can be a metal laminate film, which is made by laminating a resin film (resin sheet) such as nylon film (nylon 66 film, etc.) or polyester film (polyethylene terephthalate film, etc.) with a metal film (metal foil, metal plate) such as aluminum (including aluminum alloy) or stainless steel.

[0095] In the case of an outer casing made of laminate film, for example, two sheets of laminate film may be used, or one sheet of laminate film may be folded over to form the casing, and the sealing can be performed by fusing the overlapping laminate films together by heat sealing. In this case, to facilitate the heat sealing process, a heat-sealable resin layer may be laminated onto the laminate film before use in the outer casing. Examples of heat-sealable resins that constitute the heat-sealable resin layer include modified polyolefins (such as modified polyolefin ionomers), polyethylene and its copolymers, and polypropylene and its copolymers.

[0096] The shape of the outer casing of the electrochemical element in plan view is not particularly limited; it may be circular, or it may be a polygon such as a square or rectangle.

[0097] <Electrolytes> In the case of an electrochemical element having an electrode stack with a separator as an isolation layer, an electrolyte is used as described above. Typically, a liquid electrolyte (non-aqueous electrolyte or aqueous electrolyte) having a non-aqueous or aqueous solvent is used as the electrolyte. The non-aqueous electrolyte is prepared by dissolving an electrolyte salt such as a lithium salt in an organic solvent. The organic solvent is not particularly limited, but examples include linear esters such as dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate; cyclic esters with high dielectric constants such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate; and mixed solvents of linear esters and cyclic esters. Mixed solvents of linear esters and cyclic esters are particularly suitable.

[0098] For example, when the electrochemical element is a battery or lithium-ion capacitor, the electrolyte salts to be dissolved in the organic solvent include LiPF6, LiBF4, LiAsF6, LiSbF6, LiCF3SO3, LiC4F9SO3, LiCF3CO2, Li2C2F4(SO3)2, and LiC n F 2n+1 SO3 (n≧2), LiN(RfSO2)(Rf'SO2), LiC(RfSO2)3, LiN(RfOSO2)2 (where Rf and Rf' are fluoroalkyl groups) can be used individually or in combination of two or more. In addition, for the non-aqueous electrolyte in the case of an electric double-layer capacitor, (C2H5)4NBF4, (C2H5)4PBF4, etc., are used as the electrolyte salts.

[0099] The concentration of the electrolyte salt in the electrolyte solution is not particularly limited, but it is preferably 0.3 mol / l or higher, more preferably 0.4 mol / l or higher, and preferably 1.7 mol / l or lower, and more preferably 1.5 mol / l or lower.

[0100] Furthermore, as aqueous electrolytes, alkaline aqueous solutions (alkaline electrolytes) consisting of aqueous solutions of alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, and lithium hydroxide, or aqueous solutions with a pH in the range of 3 to 12 are used.

[0101] The concentration of alkali metal hydroxide in the alkaline electrolyte can be, for example, 25 to 40% by mass.

[0102] Furthermore, aqueous solutions with a pH in the range of 3 to 12 include solutions obtained by dissolving one or more of the following electrolyte salts in water: chlorides such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride, ammonium chloride, and zinc chloride; hydroxides of alkali metals and alkaline earth metals (sodium hydroxide, potassium hydroxide, magnesium hydroxide, etc.), acetates (sodium acetate, potassium acetate, magnesium acetate, etc.), nitrates (sodium nitrate, potassium nitrate, magnesium nitrate, etc.), sulfates (sodium sulfate, potassium sulfate, magnesium sulfate, etc.), phosphates (sodium phosphate, potassium phosphate, magnesium phosphate, etc.), borates (sodium borate, potassium borate, magnesium borate, etc.), citrates (sodium citrate, potassium citrate, magnesium citrate, etc.), glutamates (sodium glutamate, potassium glutamate, magnesium glutamate, etc.); alkali metal bicarbonates (sodium bicarbonate, potassium bicarbonate, etc.); alkali metal percarbonates (sodium percarbonate, potassium percarbonate, etc.); halogen-containing compounds such as fluorides; and polycarboxylic acids.

[0103] As the electrolyte for the electrochemical element, a gel-like electrolyte can also be used, which is obtained by gelling the aforementioned electrolyte with a gelling agent such as a polymer.

[0104] <Electrochemical element module> Electrochemical elements can be used individually, but they can also be used in the form of modules, for example, where a laminate of multiple electrochemical elements is housed in a casing made of resin or metal.

[0105] Figure 3 shows a schematic cross-sectional view of an example of an electrochemical element module. The electrochemical element module 300 shown in Figure 3 is constructed by housing a laminate consisting of three stacked electrochemical elements 200 within a housing 310. The housing 310 has a metal container 311 and a metal lid 312. The terminal portions 111c of the first electrodes of each electrochemical element 200 constituting the electrochemical element laminate are bundled together by welding or other means and connected to the inside of the container 311. In other words, the metal container 311 also serves as a terminal connecting the first electrodes of the electrochemical element module 300 (the first electrodes of each electrochemical element 200 constituting the module 300) to the application equipment.

[0106] Although not shown in the diagram, the second electrodes of each electrochemical element constituting module 300 are also bundled together by welding or other means and connected to the inside of the lid 312 of the housing 310. In other words, the metal lid 312 also serves as a terminal connecting the second electrodes of the electrochemical element module 300 (the second electrodes of each electrochemical element 200 constituting module 300) to the application equipment. An insulating layer 313 made of resin or the like is interposed between the container 311 and the lid 312.

[0107] In an electrochemical element having an outer casing made of laminate film, as shown in Figure 2, a resin foam sheet is placed between the electrode stack and the outer casing. In this case, in order to sufficiently press the electrode stack with the pressing force of the foam sheet, for example, as shown in Figure 3, multiple electrochemical elements with laminate film outer casings are stacked and housed in a housing made of resin or metal, and the foamed sheet can be used to press the electrode stack using the reaction force from the housing, thus creating an electrochemical element module. [Examples]

[0108] The present invention will be described in detail below based on examples. However, the following examples are not intended to limit the present invention.

[0109] (Example 1) Lithium titanate (Li4Ti5O) with an average particle size of 2 μm 12 (negative electrode active material) and a sulfide-based solid electrolyte (Li) with an average particle size of 0.7 μm. 7.0 A negative electrode mixture was prepared by mixing PS6Cl and graphene (a conductive additive) in a mass ratio of 50:41:9.

[0110] Furthermore, LiCoO2 (positive electrode active material) with an average particle size of 5 μm and a LiNbO3 coating layer formed on its surface, and a sulfide-based solid electrolyte (Li) with an average particle size of 3 μm. 7.0 A cathode mixture was prepared by mixing PS6Cl, carbon black, and vapor-grown carbon fibers (VGCF) in a mass ratio of 70:26.8:1.1:2.1.

[0111] Next, a sulfide-based solid electrolyte (Li) with an average particle size of 0.7 μm 7.0 A powder mold was placed in a powder molding die, and pressure molding was performed using a press to form a preliminary layer of the solid electrolyte. Furthermore, the negative electrode mixture was placed on the upper surface of the preliminary layer of the solid electrolyte and pressure molding was performed to form another preliminary layer of the negative electrode on top of the preliminary layer of the solid electrolyte.

[0112] Furthermore, after inverting the mold, the positive electrode mixture was placed on the upper surface of the pre-formed solid electrolyte layer inside the mold (the side opposite to the side with the pre-formed negative electrode layer) and pressure molding was performed to obtain an electrode laminate having a positive electrode (thickness: 900 μm) on one side of a solid electrolyte layer with a thickness of 150 μm and a negative electrode (thickness: 1300 μm) on the other side.

[0113] A nickel-based foamed metal porous material [Nickel-based "Cellmet" (registered trademark)] (thickness: 1.2 mm, porosity: 98%) from Sumitomo Electric Industries was pressed to form a porous sheet with a thickness of 0.5 mm. Next, the porous sheet was cut to a diameter of 7 mm to produce current collector 1, and similarly, the porous sheet was cut to a 7 mm x 7 mm square to produce current collector 2. First, the current collector 1 was inserted into the bottom of the recess of an outer container having a cross-sectional structure similar to that shown in Figure 1, with the lid-side portion of the recess's side wall made of iron-nickel-cobalt alloy and the other parts made of ceramics, and the electrode stack was placed on top of it with the positive electrode facing downwards. Next, the current collector 2 was placed on top of the negative electrode of the electrode stack, and then a foamed adhesive sheet "SAFB" (product name) (thickness: 50 μm) from Nikkan Industries, cut to a 7 mm x 7 mm square, was placed on top. Subsequently, a lid made of an iron-nickel-cobalt alloy was placed on the side wall of the recess in the outer container and welded to it, thereby sealing the outer container and its lid. During sealing, there was a 100 μm gap between the upper surface of the foamed adhesive sheet and the lower surface of the lid, allowing for successful sealing without any problems.

[0114] Furthermore, when the foam adhesive sheet used in the assembly was heated at 150°C for 10 minutes or more, separately from the foam adhesive sheet used in the assembly, without being sealed inside the outer casing, its thickness increased to 225 μm (4.5 times the thickness before heating). This confirmed that the foam adhesive sheet, when heated and transformed into a foam sheet, is capable of sealing the gaps and pressing the current collector and electrode laminate together.

[0115] Next, the sealed outer casing was heated at 150°C for 20 minutes to foam the foam adhesive sheet and form a foamed sheet. As a result, the foamed sheet, which had increased in thickness, pressed against the current collector 1, the electrode laminate, and the current collector 2, allowing electrical contact between each current collector, the electrode, and the conductive path formed in the outer casing, thereby obtaining the electrochemical element shown in Figure 1.

[0116] (Comparative Example 1) An electrochemical element was fabricated in the same manner as in Example 1, except that current collectors 1 and 2 were changed to nickel plates with a thickness of 0.5 mm, and conductive connections between current collectors 1 and 2 and the positive and negative electrodes, and between current collectors 1 and 2 and the conductive paths formed in the outer casing were made using conductive adhesive, without using a foam adhesive sheet.

[0117] Each of the fabricated electrochemical elements was charged and discharged, and its discharge capacity and internal resistance were measured. It was confirmed that the electrochemical elements in the examples had characteristics equivalent to those of the electrochemical elements in the comparative examples, and that there was no decrease in sealing performance or characteristics.

[0118] (Example 2) <Preparation of solid electrolyte sheets> A slurry with a solid content of 40% was prepared by mixing sulfide-based solid electrolyte (Li6PS5Cl) particles with an average particle size of 1 μm, an acrylic resin binder, and a dispersant with xylene ("super dehydrated" grade) as a solvent in a mass ratio of 100:3:1. 2 The slurry was applied to a PET nonwoven fabric by passing it through an applicator with a 40 μm gap, and then vacuum-dried at 120°C for 1 hour to obtain a solid electrolyte sheet. In the solid electrolyte sheet, the proportion of binder to the total amount of solid electrolyte particles was 2.9% by mass.

[0119] <Fabrication of the positive electrode> LiNi particles with an average particle size of 3 μm, having an amorphous composite oxide layer of Li and Nb formed on the surface. 0.6 Co 0.2 Mn 0.2O2, a sulfide solid electrolyte (Li6PS5Cl), a conductive additive carbon nanotube (Showa Denko Corporation's "VGCF" product name), and an acrylic resin binder were mixed with xylene ("super dehydrated" grade) as a solvent in a mass ratio of 70:24:3:3 to prepare a slurry with a solid content ratio of 60%. This slurry was applied to a 20 μm thick aluminum foil current collector with pre-attached current-collecting tabs, and vacuum-dried at 120°C to obtain a positive electrode.

[0120] <Fabrication of the negative electrode> A slurry with a solid content of 50% was prepared by mixing graphite with an average particle size of 20 μm, a sulfide solid electrolyte (Li6PS5Cl), a conductive additive carbon nanotube (Showa Denko Corporation's "VGCF" (product name)), and an acrylic resin binder with xylene ("super dehydrated" grade) as a solvent in a mass ratio of 50:44:3:3. This slurry was applied to a 20 μm thick SUS foil current collector with pre-attached current collecting tabs, and the negative electrode was obtained by vacuum drying at 120°C.

[0121] <Assembly of electrochemical elements> The positive electrode, the negative electrode, and the solid electrolyte sheet are stacked so that the current collectors of each electrode are on the outside and the solid electrolyte sheet is interposed between the two electrodes, with a load capacity of 10 tons / cm². 2 The electrodes were then pressed together to form a single unit, and the portion excluding the current collection tabs was cut to a size of 30mm x 40mm to obtain an electrode laminate.

[0122] A sealant film was attached to the portion of the current-collecting tab of each electrode of the electrode stack that would be sandwiched between aluminum laminate films and heat-sealed. Furthermore, the same foam adhesive sheet as in Example 1 was cut to a size of 30 mm x 40 mm and placed on top of the electrode stack. Both were then inserted inside the aluminum laminate film which was folded in the middle, and the whole was sandwiched and fixed from both sides. Next, the outer edges of the aluminum laminate film were heat-sealed on three sides to form an outer casing, and the excess sealed portion was cut off. Except for the connection configuration between the positive and negative electrode current collectors and the terminals, an electrochemical element with a structure similar to that shown in Figure 2 was fabricated.

[0123] <Fabrication of electrochemical element modules> After being housed in the aforementioned stainless steel housing, the laminate was heated at 150°C for 20 minutes to foam the foam adhesive sheet and form a foamed sheet. Before heating, there was a gap of approximately 300 μm between the laminate and the housing, but the foamed sheet, which increased in thickness after foaming, filled the gap and pressed down on each electrode laminate, making it possible to obtain an electrochemical element module with a structure similar to that shown in Figure 3.

[0124] (Comparative Example 2) An electrochemical element was fabricated in the same manner as in Example 2, except that the electrode laminate was not placed on top of the foam adhesive sheet electrode laminate, but only the electrode laminate was inserted inside the aluminum laminate film and the aluminum laminate film was heat-sealed.

[0125] Three of the aforementioned electrochemical elements were stacked to form a laminate, and both sides of the laminate were fixed to a jig and pressed at 0.2 MPa to obtain an electrochemical element module.

[0126] (Comparative Example 3) Three of the same electrochemical elements as in Comparative Example 2 were stacked to form a laminate, and both sides of the laminate were fixed to a jig, but the laminate was not pressed down to form an electrochemical element module.

[0127] The electrochemical element modules of Example 2, Comparative Example 2, and Comparative Example 3 were charged and discharged, and their discharge capacity and internal resistance were measured. The electrochemical element module of Example 2 had characteristics equivalent to those of the electrochemical element module of Comparative Example 2, confirming that the pressure of the electrode laminate by the foam sheet was functioning sufficiently.

[0128] On the other hand, in Comparative Example 3, the electrochemical element module lacked pressure on the electrode stack, resulting in a decrease in discharge capacity and an increase in internal resistance.

[0129] The present invention can also be implemented in forms other than those described herein, without departing from its spirit. The embodiments disclosed herein are examples, and the present invention is not limited to these embodiments. The scope of the present invention shall be interpreted in accordance with the claims attached, which take precedence over the description herein, and all modifications within the scope equivalent to the claims are included in the claims. [Industrial applicability]

[0130] The electrochemical element of the present invention can be applied to the same applications as conventionally known electrochemical elements, and the module of the electrochemical element of the present invention can be applied to the same applications as conventionally known modules of electrochemical elements. [Explanation of Symbols]

[0131] 100, 200 electrochemical elements 110 Electrode Stack 111 1st electrode 111a First electrode active material layer 111b First electrode current collector 111c Terminal portion of the first electrode 112 2nd electrode 112a Second electrode active material layer 112b Second electrode current collector 113 Isolation layer 120, 121 Current collector 130 Resin foam sheet 140 Outer container 150 Lid 160, 170 External terminals 161, 171 Conduction path 300 Electrochemical Element Modules 310 cabinets 311 Container 312 Lid 313 Insulating layer

Claims

1. An electrochemical element having an outer casing and an electrode laminate sealed inside the outer casing, The electrode stack comprises a flat plate-shaped first electrode, a flat plate-shaped second electrode, and an isolation layer interposed between the first electrode and the second electrode. A foamed resin sheet is placed between the electrode laminate and the outer casing. The exterior body has an external terminal for a first electrode, partly exposed to the outside, and a conductive path for a first electrode connecting the external terminal for the first electrode to the first electrode of the electrode stack, and an external terminal for a second electrode, partly exposed to the outside, and a conductive path for a second electrode connecting the external terminal for the second electrode to the second electrode of the electrode stack. An electrochemical element characterized in that the foamed sheet presses the electrode laminate toward the conductive path side for the first electrode or the conductive path side for the second electrode.

2. The electrochemical element according to claim 1, wherein the isolation layer is a solid electrolyte layer.

3. A current collector is placed between the electrode laminate and the foam sheet. The electrochemical element according to claim 1, wherein the foamed sheet presses the electrode laminate via the current collector.

4. The electrochemical element according to claim 1, wherein the foamed sheet is formed by heating a resin sheet that foams and expands upon heating.

5. An electrochemical element module characterized by comprising a laminate in which a plurality of electrochemical elements according to any one of claims 1 to 4 are stacked, and housed in a housing.

6. A method for manufacturing the electrochemical element described in Claim 1, The electrode stack comprises a first electrode, a second electrode, and an isolation layer interposed between the first electrode and the second electrode. A sealing step in which a resin sheet that foams and expands upon heating and the electrode laminate are sealed inside the outer casing, A method for manufacturing an electrochemical element, characterized by comprising a heating step of heating the resin sheet to cause foaming and pressing the electrode laminate with the expanded resin sheet.

7. The method for manufacturing an electrochemical element according to claim 6, wherein the temperature at which the resin sheet is heated is 195°C or lower.

8. The method for manufacturing an electrochemical element according to claim 6, wherein the thickness of the resin sheet before heating is 10 to 2000 μm.

9. The method for manufacturing an electrochemical element according to claim 6, wherein the isolation layer is a solid electrolyte layer.

10. A current collector is placed between the electrode laminate and the resin sheet. A method for manufacturing an electrochemical element according to claim 6, wherein the electrode laminate is pressed by the foamed resin sheet via the current collector.

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