Patent Publication Number: US-2022231343-A1

Title: Solid-state battery and solid-state battery unit

Description:
This application is based on and claims the benefit of priority from Japanese Patent Application No. 2021-005949, filed on 18 Jan. 2021, the content of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a solid-state battery and a solid-state battery unit. 
     Related Art 
     In recent years, the proliferation of electrical and electronic devices of various sizes, such as automobiles, personal computers, and cell phones, has led to a drastically increasing demand for high-capacity, high-output batteries. One such battery is a solid-state battery including a laminate in which a flame-retardant solid-state electrolyte is interposed between the positive electrode and the negative electrode. Examples of such solid-state batteries include a solid-state battery in which the laminate is covered with resin. 
     For example, Patent Document 1 describes a solid-state battery in which a solid battery element is covered with a thermosetting resin or a thermoplastic resin. In addition, Patent Document 2 describes a solid-state battery in which at least a side surface of an all-solid-state battery laminate is covered, and a cavity is present between a side surface of at least a negative electrode active material layer and a resin casing. 
     Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2000-106154 
     Patent Document 2: Japanese Unexamined Patent Application, Publication No. 2019-121532 
     SUMMARY OF THE INVENTION 
     In a solid-state battery in which the laminate is covered with resin as in Patent Document 1, a change in volume of the negative electrode active material layer in the laminate occurs due to charging or discharging, and there is thus a risk of cracks occurring in the resin casing. To address this concern, the solid-state battery of Patent Document 2 has a cavity between the side surface of the negative electrode active material layer and the resin casing, which allows the negative electrode active material layer to expand in a direction orthogonal to the laminating direction if a change in volume of the negative electrode active material occurs, allowing for suppression of the occurrence of cracks in the resin casing. 
     However, in the solid-state battery of Patent Document 2, the presence of the cavity between the side surface of the negative electrode active material layer and the resin casing means that the side surface of the laminate in the direction orthogonal to the laminating direction, as well as any current collector tabs formed on said side surface, would not be sufficiently protected, and there is therefore room for improvement in terms of assuring greater mechanical strength. 
     The present invention has an object of providing a solid-state battery or a solid state battery unit including a laminate covered with a resin casing, which is capable of ensuring a higher mechanical strength while suppressing damage to the resin casing due to changes in volume of the laminate. 
     The present invention relates to a solid-state battery including: a solid-state battery cell including a laminate having at least one positive electrode having a positive electrode current collector and a positive electrode active material layer, at least one negative electrode having a negative electrode current collector and a negative electrode active material layer, and a solid-state electrolyte interposed between the positive electrode and the negative electrode, and a first elastic member arranged at least on both sides of the laminate in a laminating direction; and a resin casing that is made of a thermosetting resin or a thermoplastic resin and closely adheres to and covers the solid-state battery cell. 
     The solid-state battery cell may further include a positive electrode current collector tab extending in a direction away from the laminate from an end portion of the positive electrode current collector in a direction orthogonal to the laminating direction; and a negative electrode current collector tab extending in a direction away from the laminate from an end portion of the negative electrode current collector in a direction orthogonal to the laminating direction, the resin casing closely adhering to and covering the positive electrode current collector tab and the negative electrode current collector tab. 
     A surface of the first elastic member that is in contact with the laminate may have an area equal to or greater than that of a surface of the negative electrode active material layer orthogonal to the laminating direction. 
     A total maximum compression amount in a thickness direction of the first elastic member arranged on both sides of the laminate in the laminating direction may be greater than a maximum expansion amount of the laminate. 
     A negative electrode active material constituting the negative electrode active material layer may be hard carbon. 
     A negative electrode active material constituting the negative electrode active material layer may be graphite, and a capacity ratio (negative capacity/positive capacity) of the negative electrode and the positive electrode may be 1.1 or more. 
     The present invention also relates to a solid-state battery unit including: a solid-state battery module including a group of a plurality of laminates each having at least one positive electrode having a positive electrode current collector and a positive electrode active material layer, at least one negative electrode having a negative electrode current collector and a negative electrode active material layer, and a solid-state electrolyte interposed between the positive electrode and the negative electrode, the laminates being stacked in a laminating direction of each laminate, and a second elastic member arranged at least on both sides of the laminate group in the laminating direction; and a module resin casing made of a thermosetting resin or a thermoplastic resin and which closely adheres to and covers the solid-state battery module. 
     The second elastic member may be arranged on both sides in the laminating direction of each of the plurality of laminates. 
     According to the present invention, it is possible to provide a solid-state battery or a solid-state battery unit including a laminate covered with a resin casing, which is capable of ensuring a higher mechanical strength while suppressing damage to the resin casing due to changes in volume of the laminate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view showing a solid-state battery according to an embodiment of the present invention; 
         FIG. 2  is a cross-sectional view taken along line A-A in  FIG. 1 ; 
         FIG. 3  is a perspective view showing a solid-state battery unit according to an embodiment of the present invention; and 
         FIG. 4  is a cross-sectional view taken along line B-B in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present invention is described below with reference to the drawings. However, the embodiment shown below is merely an example of the present invention, and the invention is not limited to this embodiment. 
     &lt;Solid-State Battery&gt; 
     A solid-state battery  1  according to the present invention is described with reference to  FIG. 1  and  FIG. 2 .  FIG. 1  is a perspective view of the solid-state battery  1 .  FIG. 2  is a cross-sectional view taken along line A-A of the solid-state battery  1  in  FIG. 1 . It should be noted that, in  FIG. 1 , a resin casing  300  is shown by a long-dash double-short-dash line, and in  FIG. 2 , hatching of lead terminals  200  and the resin casing  300  is omitted to avoid complication of the illustration. 
     As shown in  FIG. 1  and  FIG. 2 , the solid-state battery  1  according to the present embodiment, includes a solid-state battery cell  100 , lead terminals  200 , and a resin casing  300 . 
     (Solid-State Battery Cell) 
     The solid-state battery cell  100  includes a laminate  110 , a positive electrode current collector tab  120 , a negative electrode current collector tab  130 , and first elastic members  140 . 
     [Laminate] 
     The laminate  110  has at least one positive electrode  10 , at least one negative electrode  20 , and a solid-state electrolyte  30  interposed between the positive electrode  10  and the negative electrode  20 . In the present embodiment, as shown in  FIG. 2 , the laminate as a whole has an approximately rectangular cuboidal shape, where three positive electrodes  10  in the form of positive electrodes  10   a,    10   b,  and  10   c,  four negative electrodes  20  in the form of negative electrodes  20   a,    20   b,    20   c,  and  20   d,  and six solid-state electrolytes  30  in the form of solid-state electrolytes  30   a,    30   b,    30   c,    30   d,    30   e,  and  30   f,  are laminated. Specifically, the above elements are laminated in the following order from one side (the upper side in  FIG. 2 ) in a laminating direction C of the laminate  110 : negative electrode  20   a,  solid-state electrolyte  30   a,  positive electrode  10   a,  solid-state electrolyte  30   b,  negative electrode  20   b,  solid-state electrolyte  30   c,  positive electrode  10   b,  solid-state electrolyte  30   d,  negative electrode  20   c,  solid-state electrolyte  30   e,  positive electrode  10   c,  solid-state electrolyte  30   f,  negative electrode  20   d.  The laminating direction C is indicated by a double-headed arrow in  FIG. 2 . 
     [Positive Electrode] 
     Each of the three positive electrodes  10  has a plate-shaped positive electrode current collector  11  and plate-shaped positive electrode active material layers  12 . As shown in  FIG. 2 , the positive electrode active material layers  12  are arranged on both surfaces of the positive electrode current collector  11  in the laminating direction C. 
     [Positive Electrode Current Collector] 
     The positive electrode current collector  11  is not particularly limited, and any well-known current collector usable in positive electrodes of solid-state batteries may be applied. Examples include metallic foils such as a stainless steel (SUS) foil, an aluminum (Al) foil, etc. 
     A positive electrode current collector tab  120  is formed at an end portion  111  on one side (the left side in  FIG. 2 ) of the positive electrode current collector  11  in a direction orthogonal to the laminating direction C. Specifically, the positive electrode current collector tabs  120  of the positive electrodes  10   a  to  10   c  extend in a direction away from the laminate  110  at the end portions  111  of the respective positive electrode current collectors  11 . 
     The respective positive electrode current collector tabs  120  of the positive electrodes  10   a  to  10   c  are bonded to a lead terminal  200  described later, with their end portions opposite from the laminate  110  being bundled together. The bonding method is not particularly limited, and any well-known method, including welding methods such as vibration welding or ultrasonic welding, etc. may be used. 
     The positive electrode current collector tab  120  may be formed in one piece with the positive electrode current collector  11 , or it may be a different member from the positive electrode current collector  11  and be electrically connected to the end portion  111  of the positive electrode current collector  11  by welding or the like. The positive electrode current collector tab  120  according to the present embodiment is formed in one piece with the positive electrode current collector  11 . In the present embodiment, the positive electrode current collector  11  is a portion that is in contact with the positive electrode active material layer  12  of one metallic foil and is pressed out by pressure in the laminating direction C, and the positive electrode current collector tab  120  is a portion that is not in contact with the positive electrode active material layer  12  of the one metallic foil and is not pressed out. This means that a weak fragile portion  121  is formed at the boundary between the pressed positive electrode current collector  11  and the unpressed positive electrode current collector tab  120 . 
     The width of the positive electrode current collector tab  120  is appropriately set to minimize resistance according to the intended use, with the width of the bonding material being the maximum width, and is preferably 1 mm to 1000 mm, and more preferably 2 mm to 300 mm. The thickness is generally about 5 to 50 μm, and the length is generally 5 to 50 mm. 
     [Positive Electrode Active Material Layer] 
     The material constituting the positive electrode active material layer  12  is not particularly limited, and any material known to be usable as a positive electrode active material in a solid-state battery may be applied. The composition thereof is also not particularly limited, and may include, other than the positive electrode active material, a solid-state electrolyte, an electroconductive agent, etc. 
     Positive electrode active materials include, for example, transition metal chalcogenides such as titanium disulfide, molybdenum disulfide, and niobium selenide, and transition metal oxides such as lithium nickel oxide (LiNiO 2 ), lithium manganese oxide (LiMnO 2 , LiMn 2 O 4 ), and lithium cobalt oxide. (LiCoO 2 ). 
     [Negative Electrode] 
     Each of the four negative electrodes  20  has a plate-shaped negative electrode current collector  21  and a plate-shaped negative electrode active material layer  22 . As shown in  FIG. 2 , the negative electrode active material layers  22  are arranged on one or both surfaces of the negative electrode current collector  21  in the laminating direction C. 
     [Negative Electrode Current Collector] 
     The negative electrode current collector  21  is not particularly limited, and any well-known current collector usable in negative electrodes of solid-state batteries may be applied. Examples include metallic foils such as a stainless steel (SUS) foil, a copper (Cu) foil, etc. 
     A negative electrode current collector tab  130  is formed at an end portion  211  on the other side (the right side in  FIG. 2 ) of the negative electrode current collector  21  in a direction orthogonal to the laminating direction C. Specifically, the negative electrode current collector tabs  130  of the negative electrodes  20   a  to  20   d  extend in a direction away from the laminate  110  at the end portions  211  of the respective negative electrode current collectors  21 . 
     The respective negative electrode current collector tabs  130  of the negative electrodes  20   a  to  20   d  are bonded to a lead terminal  200  described later, with their end portions opposite from the laminate  110  being bundled together. The bonding method is not particularly limited, and any well-known method, including welding methods such as vibration welding or ultrasonic welding, etc. may be used. 
     The negative electrode current collector tab  130  may be formed in one piece with the negative electrode current collector  21 , or it may be a different member from the negative electrode current collector  21  and be electrically connected to the end portion  211  of the negative electrode current collector  21  by welding or the like. The negative electrode current collector tab  130  according to the present embodiment is formed in one piece with the negative electrode current collector  21 . In the present embodiment, the negative electrode current collector  21  is a portion that is in contact with the negative electrode active material layer  22  of one metallic foil and is pressed out by pressure in the laminating direction C, and the negative electrode current collector tab  130  is a portion that is not in contact with the negative electrode active material layer  22  of the one metallic foil and is not pressed out. This means that a weak fragile portion  131  is formed at the boundary between the pressed negative electrode current collector  21  and the unpressed negative electrode current collector tab  130 . 
     The width of the negative electrode current collector tab  130  is appropriately set to minimize resistance according to the intended use, with the width of the bonding material being the maximum width, and is preferably 1 mm to 1000 mm, and more preferably 2 mm to 300 mm. The thickness is generally about 5 to 50 μm, and the length is generally 5 to 50 mm. 
     [Negative Electrode Active Material Layer] 
     The material constituting the negative electrode active material layer  22  is not particularly limited, and any material known to be usable as a negative electrode active material in a solid-state battery may be applied. The composition thereof is also not particularly limited, and may include, other than the negative electrode active material, a solid-state electrolyte, an electroconductive agent, etc. 
     The negative electrode active material is not particularly limited, so long as it can absorb and release lithium ions. Negative electrode active materials include, for example, metallic lithium, a lithium alloy, a metal oxide, a metal nitride, Si, SiO, and carbon materials such as graphite, hard carbon, soft carbon, etc. Considering the small volume change of the negative electrode  20 , hard carbon, which exhibits a small volume change due to electric charge and discharge is preferably used as the negative electrode active material. In addition, similar to hard carbon, considering the small volume change of the negative electrode  20 , it is preferable to use graphite as the negative electrode active material and to make the capacity ratio (negative capacity/positive capacity) of the negative electrodes  20  and the positive electrodes  10  be 1.1 or more. 
     [Solid-State Electrolyte] 
     The solid state electrolyte  30  is laminated between the positive electrodes  10  and the negative electrodes  20 , and is formed, for example, as layers. The solid-state electrolyte  30  is a layer that contains at least a solid-state electrolyte material. Charge transfer between the positive electrode active material and the negative electrode active material can be performed through the above solid-state electrolyte material. 
     The solid-state electrolyte material is not particularly limited, and may be, for example, a sulfide solid-state electrolyte material, an oxide solid-state electrolyte material, a nitride solid-state electrolyte material, a halide solid-state electrolyte material, etc. 
     [First Elastic Member] 
     The first elastic member  140  is a plate-shaped, highly elastic member. The first, elastic member  140  may be natural rubber, diene rubber, non-diene rubber, etc. In the present embodiment, a styrene-butadiene rubber plate is used as the first elastic member  140 . 
     The first elastic members  140  are arranged at least on both sides of the laminate  110  in the laminating direction C. In the present embodiment, as shown in  FIG. 1  and  FIG. 2 , two first elastic members  140  in the form of a first elastic member  140   a  and a first elastic member  140   b  are arranged on both sides of the laminate  110  in the laminating direction C. 
     The first elastic member  140   a  is arranged on one side (the upper side in  FIG. 2 ) of the laminate  110  in the laminating direction C, and the first elastic member  140   b  is arranged on the other side (the lower side in  FIG. 2 ) of the laminate  110  in the laminating direction C. Specifically, the first elastic member  140   a  is arranged to be in contact with the entire surface of the negative electrode current collector  21  of the negative electrode  20   a  on one side in the laminating direction C (the upper side in  FIG. 2 ), and the first elastic member  140   b  is arranged to be in contact with the entire surface of the negative electrode current collector  21  of the negative electrode  20   d  on the other side (the lower side in  FIG. 2 ) in the laminating direction C. According to this configuration, even if, for example, charging of the solid-state battery  1  causes the negative electrode active material layers  22  to expand, increasing the volume of the laminate  110 , the first elastic members  140  can be compressed in the laminating direction C in response to the increase in volume. That is to say, even if the volume of the laminate  110  increases, compression of the first elastic members  140  can maintain a constant overall volume of the solid-state battery cell  100 . 
     The area of the surface of the first elastic member  140   a  in contact with the laminate  110  is equal to or greater than the areas of the surfaces of the negative electrode active material layers  22  of the electrodes  20  orthogonal to the laminating direction C. Likewise, the area of the surface of the first elastic member  140   b  in contact, with the laminate  110  is equal to or greater than the areas of the surfaces of the negative electrode active material layers  22  of the electrodes  20  orthogonal to the laminating direction C. 
     In addition, the solid-state battery cell  100  is configured so that a total maximum compression amount in the thickness direction of the first elastic members  140  arranged on both sides of the laminate  110  in the laminating direction C is greater than a maximum expansion amount of the laminate  110 . Specifically, it is configured so that the total maximum compression amount in the thickness direction of the first elastic members  140   a,    140   b  is greater than the total expansion amount of all the negative electrode active material layers  22  included in the laminate  110 . It should be noted that the dimensions, such as thickness, length, and width, as well as the materials of the first elastic members  140   a,    140   b  may be the same or different. 
     (Lead Terminal) 
     As shown in  FIG. 2 , an end portion  201  on one side (the laminate  110  side in  FIG. 2 ) of the lead terminal  200  is electrically connected to the plurality of positive electrode current collector tabs  120  or negative electrode current collector tabs  130  by welding or the like, and an end portion  202  on the other side (the opposite side from the laminate  110  in  FIG. 2 ) extends from the resin casing  300  to the outside, constituting an electrode portion of the solid-state battery cell  100 . The material of the lead terminal  200  may be the same material as that of a current collector tab lead used in a conventional solid-state battery, and is not particularly limited. 
     As shown in  FIG. 2 , in the present embodiment, two lead terminals  200  in the form of lead terminals  200   a  and  200   b  are connected to the solid-state battery cell  100 . Specifically, the lead terminal  200   a  is connected to the plurality of positive electrode current collector tabs  120 , and the lead terminal  200   b  is connected to the plurality of negative electrode current collector tabs  130 . 
     (Resin Casing) 
     The resin casing  300  is made from a thermosetting resin or a thermoplastic resin. The resin used in the resin casing  300  preferably has a melting point that is less than 200° C., which is the temperature at which the positive electrode active material, negative electrode active material, and solid-state catalyst of the solid-state battery  1  are affected. Types of resin include, for example, polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polystyrene (PS), acrylonitrile-styrene resin (AS), acrylonitrile-butadiene-styrene resin (ABS), polyethylene (PE), ethylene vinyl acetate (EVA), polypropylene (PP), polyacetal (POM), acrylic resin (PMMA), methyl methacrylate-styrene copolymer (MS), polycarbonate (PC), polyurethane (PU), polyvinylidene fluoride (PVDF), etc. 
     The resin casing  300  closely adheres to and covers the entire solid-state battery cell  100 . In other words, the resin casing  300  closely adheres to and covers the four side surfaces of the laminate  110  orthogonal to the laminating direction C, the four side surfaces orthogonal to the laminating direction C and the surface opposite the surface in contact with the laminate  110  in the laminating direction C of each first elastic member  140 , the positive electrode current collector tabs  120 , and the negative electrode current collector tabs  130 . In addition, the resin casing  300  closely adheres to and covers the respective end portions  201  of the lead terminal  200   a  connected to the plurality of positive electrode current; collector tabs  120  and the lead terminal  200   b  connected to the plurality of negative electrode current collector tabs  130 . 
     The method for forming the resin casing  300  is not particularly limited, and any known method may be used. For example, the resin casing  300  may be formed by placing the solid-state battery cell  100  with the lead terminals  200   a  and  200   b  connected thereto in a die, filling the die with a thermosetting resin or a thermoplastic resin in liquid form at or below the melting point, and then curing the resin. At this time, the respective end portions  202  of the lead terminals  200   a  and  200   b  are arranged outside of the die, and the respective end portions  201  of the lead terminals  200   a  and  200   b  are positioned inside the die. 
     The solid-state battery  1  according to the present embodiment, exhibits the following effects. The solid-state battery  1  according to the present embodiment includes: a solid-state battery cell  100  including a laminate  110 , the laminate  110  having at least one positive electrode  10  having a positive electrode current collector  11  and a positive electrode active material layer  12 , at least one negative electrode  20  having a negative electrode current collector  21  and a negative electrode active material layer  22 , and a solid state catalyst  30  interposed between the positive electrode  10  and the negative electrode  20 , and first elastic members  140  arranged at least on both sides of the laminate  110  In the laminating direction C; and a resin casing  300  made of a thermosetting resin or a thermoplastic resin and which closely adheres to and covers the solid-state battery cell  100 . The resin casing  300  thus closely adheres to and covers the entire solid-state battery cell  100  including the laminate  110 , allowing for more reliable protection of the entire solid-state battery cell  100 . Further, even if the entire solid-state battery cell  100  is covered by the resin casing  300  without any gaps, if a change in volume of the laminate  110  occurs due to expansion of the negative electrode active material layers  22  caused by charging or discharging, the first elastic members  140  interposed between the laminate  110  and the resin casing  300  will be compressed according to the change in volume. In other words, even if the volume of the laminate  110  in the laminating direction C changes, the compression of the first elastic members  140  allows for suppression of the occurrence of cracks in the resin casing  300 . It is thus possible to ensure a higher mechanical strength of the solid-state battery  1  while suppressing damage to the resin casing  300  due to changes in volume of the laminate  110 . 
     In addition, the solid-state battery cell  100  of the solid-state battery  1  according to the present embodiment further includes positive electrode current collector tabs  120  extending, in a direction away from the laminate  110 , from the end portions  111  of the positive electrode current collectors  11  in a direction orthogonal to the laminating direction C, and negative electrode current collector tabs  130  extending, in a direction away from the laminate  110 , from the end portions  211  of the negative electrode current collectors  21  in a direction orthogonal to the laminating direction C, and the resin casing  300  closely adheres to and covers the positive electrode current collector tabs  120  and the negative electrode current collector tabs  130 . The entirety of the positive electrode current collector tabs  120  including the weak fragile portions  121 , and the entirety of the negative electrode current collector tabs  130  including the weak fragile portions  131 , are thus protected by the resin casing  300 . It is thus possible to improve the mechanical strength of the positive electrode current collector tabs  120  and the negative electrode current collector tabs  130  while suppressing the occurrence of cracks in the resin casing  300  by means of the first elastic members  140  that can compress and expand according to changes in volume of the laminate  110 . 
     In addition, in the solid-state battery cell  100  of the solid-state battery  1  according to the present embodiment, the area of the surface of each first elastic member  140  in contact with the laminate  110  is equal to or greater than the areas of the surfaces of the negative electrode active material layers  22  orthogonal to the laminating direction C. This allows for expansion and compression of the first elastic members  140  according to a change in volume of the entire surface of the negative electrode active material layers  22  orthogonal to the laminating direction C. It is thus possible to more reliably suppress damage to the resin casing  300  due to changes in volume of the laminate  110 . 
     In addition, in the solid-state battery  1  according to the present embodiment, the total maximum compression amount in the thickness direction of the first elastic members  140  arranged on both sides of the laminate  110  in the laminating direction C is greater than the maximum expansion amount of the laminate  110 . Therefore, even if all of the negative electrode active material layers  22  in the laminate  110  were to expand by the maximum expansion amount in the laminating direction C, the first elastic members  140  arranged by the laminate  110  will be compressed according to the expansion, which makes it possible to more reliably suppress damage to the resin casing  300  due to changes in volume of the laminate  110 . 
     In addition, in the solid-state battery  1  according to the present invention, the negative electrode active material constituting the negative electrode active material layers  22  is hard carbon. This allows for a reduction of the volume change amount of the laminate  110  due to expansion or contraction of the negative electrode active material layers  22  caused by charging or discharging. 
     In addition, in the solid-state battery  1  according to the present embodiment, the negative electrode active material constituting the negative electrode active material layers  22  is a graphite active material, and the capacity ratio (negative capacity/positive capacity) of the negative electrodes  20  and the positive electrodes  10  is 1.1 or more. This allows for a reduction of the volume change amount of the laminate  110  due to expansion or contraction of the negative electrode active material layers  22  caused by charging or discharging. 
     &lt;Solid-State Battery Unit&gt; 
     Next, a solid-state battery unit  1 A according to the present embodiment is described with reference to  FIG. 3  and  FIG. 4 .  FIG. 3  is a perspective view of the solid-state battery unit  1 A.  FIG. 4  is a cross-sectional view taken along line B-B of the solid-state battery unit  1 A in  FIG. 3 . It should be noted that, in  FIG. 3 , a module resin casing  400  is shown by a long-dash double-short-dash line, and in  FIG. 4 , hatching of lead terminals  200 A and the module resin casing  400  is omitted to avoid complication of the illustration. Moreover, the same constituents as the ones of the solid-state battery  1  are given the same reference numerals, and description thereof is omitted. 
     As shown in  FIG. 3  and  FIG. 4 , the solid-state battery unit  1 A includes a solid-state battery module  100 A, lead terminals  200 A, and a module resin casing  400 . 
     (Solid-State Battery Module) 
     The solid-state battery module  100 A includes a laminate group  110 A, a positive electrode current collector tab  120 , a negative electrode current collector tab  130 , and second elastic members  150 . 
     [Laminate Group] 
     The laminate group  110 A is composed of a plurality of laminates  110  laminated in laminating direction C. In the present embodiment, as shown in  FIG. 3  and  FIG. 4 , the laminate group  110 A has an approximately rectangular cuboidal shape, where three laminates  110  in the form of laminates  11   110   b,  and  110   c  are laminated in that order. 
     [Second Elastic Member] 
     The second elastic member  150  is a plate-shaped, highly elastic member. The second elastic member  150  may be natural rubber, diene rubber, non-diene rubber, etc. In the present embodiment, a styrene-butadiene rubber plate is used as the second elastic member  150 . 
     The second elastic members  150  are arranged at least on both sides of the laminate group  110 A in the laminating direction C. In the present embodiment, as shown in  FIG. 3  and  FIG. 4 , four second elastic members  150  in the form of second elastic members  150   a,    150   b,    150   c,  and  150   d  are arranged in the laminate group  110 A. 
     The second elastic member  150   a  is arranged on one side (the upper side in  FIG. 4 ) of the laminate group  110 A in the laminating direction C. Specifically, the second elastic member  150   a  is arranged to be in contact with the entire surface of the negative electrode current collector  21  of the negative electrode  20   a  of the laminate  110   a  on one side in the laminating direction C (the upper side in FIG. A). 
     The second elastic member  150   d  is arranged on the other side (the lower side in  FIG. 4 ) of the laminate group  110 A in the laminating direction C. Specifically, the second elastic member  150   b  is arranged to be in contact with the entire surface of the negative electrode current collector  21  of the negative electrode  20   d  on the other side (the lower side in  FIG. 4 ) of the laminate  110   c  in the laminating direction C. 
     The second elastic member  150   b  is arranged between the laminate  110   a  and the laminate  110   b.  Specifically, the second elastic member  150   b  is arranged to be in contact with the entire surface of the negative electrode current collector  21  of the negative electrode  20   d  on the other side (the lower side in  FIG. 4 ) of the laminate  110   a  in the laminating direction C, and to be in contact with the entire surface of the negative electrode current collector  21  of the negative electrode  20   a  on one side (the upper side in  FIG. 4 ) of the laminate  110   b  in the laminating direction C. 
     The second elastic member  150   c  is arranged between the laminate  110   b  and the laminate  110   c.  Specifically, the second elastic member  150   c  is arranged to be in contact, with the entire surface of the negative electrode current collector  21  of the negative electrode  20   d  on the other side (the lower side in  FIG. 4 ) of the laminate  110   b  in the laminating direction C, and to be in contact with the entire surface of the negative electrode current collector  21  of the negative electrode  20   a  on one side (the upper side in  FIG. 4 ) of the laminate  110   c  in the laminating direction C. 
     The areas of the surfaces of the second elastic members  150   a  to  150   d  in contact with the respective laminates  110  are equal to or greater than the areas of the surfaces of the negative electrode active material layers  22  in the laminates  110  orthogonal to the laminating direction C. This allows for expansion and compression of the second elastic members  150  according to a change in volume of the entire surface of the negative electrode active material layers  22  orthogonal to the laminating direction C. 
     In addition, the solid-state battery module  100 A is configured so that a total maximum compression amount in the thickness direction of all the second elastic members  150  arranged in the laminate group  110 A is greater than a maximum expansion amount of the laminate group  110 A. Specifically, it is configured so that the total maximum compression amount in the thickness direction of the second elastic members  150   a  to  150   d  is greater than the total expansion amount of all the negative electrode active material layers  22  included in the laminate group  110 A. Therefore, even if all of the negative electrode active material layers  22  in the laminate group  110 A were to expand by the maximum expansion amount in the laminating direction C, the second elastic members  150  arranged in the laminate group  110 A can be compressed according to the expansion. It should be noted that the dimensions, such as thickness, length, and width, as well as the materials of the second elastic members  150   a  to  150   d  may be the same or different. 
     (Lead Terminal) 
     As shown in  FIG. 4 , an end portion  201  on one side (the laminate group  110 A side in  FIG. 4 ) of the lead terminal  200 A is electrically connected to the plurality of positive electrode current collector tabs  120  or negative electrode current collector tabs  130  by welding or the like, and an end portion  202  on the other side (the opposite side from the laminate group  110 A in  FIG. 4 ) extends from the module resin casing  400  to the outside, constituting an electrode portion of the solid-state battery unit  1 A. The material of the lead terminal  200 A, like that of the lead terminal  200 , may be the same material as that of a current collector tab lead used in a conventional solid-state battery, and is not particularly limited. 
     As shown in  FIG. 4 , six lead terminals  200 A in the form of lead terminals  200   c,    200   d,    200   e,    200   f,    200   g,  and  200   h  are electrically connected to the solid-state battery module  100 A. Specifically, the lead terminal  200   c  is connected to the plurality of positive electrode current collector tabs  120  extending from the laminate  110   a,  the lead terminal  200   d  is connected to the plurality of negative electrode current collector tabs  130  extending from the laminate  110   a,  the lead terminal  200   e  is connected to the plurality of positive electrode current collector tabs  120  extending from the laminate  110   b,  the lead terminal  200   f  is connected to the plurality of negative electrode current collector tabs  130  extending from the laminate  110   b,  the lead terminal  200   g  is connected to the plurality of positive electrode current collector tabs  120  extending from the laminate  110   c,  and the lead terminal  200   h  is connected to the plurality of negative electrode current collector tabs  130  extending from the laminate  110   c.    
     (Module Resin Casing) 
     The module resin casing  400  is made from a thermosetting resin or a thermoplastic resin. The resin used in the module resin casing  400  may be the same type as that used in the resin casing  300  described above. 
     The module resin casing  400  closely adheres to and covers the entire solid-state battery module  100 A. In other words, the module resin casing  400  closely adheres to and covers the four side surfaces of the laminate group  110 A orthogonal to the laminating direction C, the four side surfaces orthogonal to the laminating direction C of the second elastic members  150   a  to  150   d  and the surface opposite the surface in contact with the laminate group  110 A in the laminating direction C of each of the second elastic members  150   a  and  150   d,  the positive electrode current collector tabs  120 , and the negative electrode current collector tabs  130 . In addition, the module resin casing  400  closely adheres to and covers at least the end portions  201  of the lead terminals  200   c  to  200   h  connected to the positive electrode current collector tabs  120  or the negative electrode current collector tabs  130 . 
     The method for forming the module resin casing  400  is not particularly limited, and any known method may be used. For example, the module resin casing  400  may be formed by placing the solid-state battery module  100 A with the lead terminals  200 A connected thereto in a die, filling the die with a thermosetting resin or a thermoplastic resin in liquid form at or below the melting point, and then curing the resin. At this time, the end portions  202  of the lead terminals  200 A are arranged outside of the die, and the end portions  201  of the lead terminals  200 A are positioned inside the die. 
     The solid-state battery unit  1 A according to the present embodiment exhibits the following effects. 
     The solid-state battery unit  1 A according to the present embodiment includes: a solid-state battery module  100 A including a laminate group  110 A constituted by a plurality of laminates  110  laminated in the laminating direction C, and second elastic members  150  arranged at least on both sides of the laminate group  110 A in the laminating direction C; and a module resin casing  400  made of a thermosetting resin or a thermoplastic resin and which closely adheres to and covers the solid-state battery module  100 A. This makes it possible to protect a solid-state battery module  100 A wherein a plurality of laminates  110  are arranged in parallel in one module resin casing  400 , which eliminates the need to provide a resin casing for each laminate  110 , thus allowing for miniaturization of the solid-state battery unit  1 A. In addition, since the module resin casing  400  closely adheres to and covers the entire solid-state battery module  100 A including the laminate group  110 A, the entire solid-state battery module  100 A can be more reliably protected. Further, even if the entire solid-state battery module  100 A is covered by the module resin casing  400  without any gaps, if a change in volume of the laminate group  110 A occurs due to expansion of the negative electrode active material layers  22  caused by charging or discharging, the second elastic members  150  interposed between the laminate group  110 A and the module resin casing  400  will be compressed according to the change in volume. It is thus possible to miniaturize and ensure a higher mechanical strength of the solid-state battery unit  1 A while suppressing damage to the module resin casing  400  due to changes in volume of the laminate group  110 A. 
     In addition, the second elastic members  150  of the solid-state battery unit  1 A according to the present embodiment are arranged on both sides of each of the plurality of laminates  110  in the laminating direction C. Thus, since the second elastic members  150  are arranged on both sides in the laminating direction C of each laminate  110  included in the laminate group  110 A, the second elastic members  150  can be more reliably compressed according to a change in volume of each laminate  110 . 
     In addition, the second elastic members  150  of the solid-state battery unit  1 A according to the present embodiment are insulative. This makes it possible to ensure insulation between each laminate  110  of the solid-state battery module  100 A even if the laminates  110  are connected in series. 
     An embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications are possible. 
     In the above embodiment, the laminate  110  of the solid-state battery  1  has three positive electrodes  10 , four negative electrodes  20 , and six solid-state catalysts  30 , but so long as the solid-state catalysts  30  are interposed between the positive electrodes  10  and the negative electrodes  20 , the number of positive electrodes  10 , negative electrodes  20 , and solid-state catalysts  30  of the laminate  110  is not particularly limited. For example, the number of positive electrodes  10  may be two or less, or four or more. In addition, the number of negative electrodes  20  may be three or less, or five or more. In addition, the number of solid-state catalysts  30  may be five or less, or seven or more. 
     In the above embodiment, the first elastic members  140  are arranged on both sides in the laminating direction C of the laminate  110  of the solid-state battery  1 , but first elastic members  140  may be additionally arranged at the side surfaces of the negative electrode active material layers  22  of the laminate  110  orthogonal to the laminating direction C. 
     In the above embodiment, the solid-state battery module  100 A of the solid-state battery unit  1 A has three laminates  110 , but so long as there are two or more laminates  110 , the number is not particularly limited. For example, the number of laminates  110  in the solid-state battery module  100 A, may be two, or four or more. 
     In the above embodiment, the second elastic members  150  of the solid-state battery unit  1 A are arranged on both sides in the laminating direction C of all laminates  110  in the solid-state battery module  100 A, but they may be arranged only on both sides of the laminate group  110 A. In addition, second elastic members  150  may be additionally arranged at the side surfaces of the negative electrode active material layers  22  of the laminates  110  orthogonal to the laminating direction C. Moreover, in case the laminates  110  in the solid state battery module  100 A are connected in series, an insulating member is interposed between each laminate  110 . 
     EXPLANATION OF REFERENCE NUMERALS 
       1  Solid-state battery 
       10 ,  10   a,    10   b,    10   c  Positive electrode
       11  Positive electrode current collector     12  Positive electrode active material layer     20 ,  20   a,    20   b,    20   c,    20   d  Negative electrode     21  Negative electrode current collector     22  Negative electrode active material layer     30 ,  30   a,    30   b,    30   c,    30   d,    30   e,    30   f  Solid-state electrolyte     100  Solid-state battery cell     110  Laminated structure     140 ,  140   a,    140   b  First elastic member     300  Resin casing