JP7289659B2 - Housing structure of all-solid-state battery and module structure using the same - Google Patents

Description

The present invention relates to a housing structure of an all-solid-state battery and a module structure using the same, and in particular, the outer periphery of a solid-state battery stack in which a plurality of solid-state battery elements are stacked in series and positive and negative electrode plates sandwiching the stack and serving as external terminals. The present invention relates to a housing structure of an all-solid-state battery in which space efficiency is improved by resin-sealing and integrating parts, and a module structure using the same.

Rechargeable secondary batteries are widely used in various situations. Especially in the field of automobiles, where high reliability is required, the conversion of drive systems from gasoline engines to motors is progressing, and along with this, the number of vehicles equipped with secondary batteries is increasing. In addition to electrical performance, such secondary batteries are required to be small and lightweight for applications involving movement, and at present, lithium-ion batteries are often used.

Lithium-ion batteries have good performance and are easy to use, but because they use an organic solvent-based electrolyte, it is known that there is a safety issue because if a short circuit occurs due to mechanical shock, etc., it will lead to a fire accident. ing. For this reason, in applications that require reliability, they are used with due consideration given to various safety measures and quality control.
In order to solve the safety problem of lithium-ion batteries, development of all-solid-state batteries using solid electrolytes instead of electrolytic solutions is underway.

Patent Document 1 discloses a total structure in which a negative electrode current collector layer having a negative electrode current collecting tab, a negative electrode active material layer, a solid electrolyte layer, a positive electrode active material layer, and a positive electrode current collector layer having a positive electrode current collecting tab are laminated in this order. A method for producing a laminated all-solid-state battery is disclosed, in which a solid-state battery element is housed in an outer package made of a laminate film in the same manner as a conventional lithium-ion battery, and a filler is filled and sealed while applying pressure in the stacking direction.

In Patent Document 2, a power generation unit in which a positive electrode layer, a solid electrolyte membrane, and a negative electrode layer are laminated in this order is housed in a battery case and sealed with a fluid sealant. A stationary solid state battery is disclosed.

In both the all-solid-state battery of Patent Document 1 and the solid-state battery of Patent Document 2, the external terminal of the battery is formed as a tab extended from the current collector or pulled out in parallel with the current collector. When these batteries are used as a module by connecting them in series because they require a high voltage, a connection area for connecting the tabs is required, resulting in wasted space.
Therefore, there is a demand for a housing structure for all-solid-state batteries that can be modularized without taking up unnecessary space for series connection.

JP 2018-133175 A JP 2009-252548 A

The present invention has been made in view of the problems in the conventional all-solid-state battery described above. An object of the present invention is to provide a housing structure for an all-solid-state battery in which space efficiency is improved by integrating the positive and negative electrode plates by resin-sealing the outer periphery thereof, and a module structure using the same.

The housing structure of the all-solid-state battery according to the present invention, which has been made to achieve the above object, comprises a positive electrode in which a positive electrode is formed on one side of a current collector, and a surface facing the positive electrode and facing the positive electrode of the current collector. A negative electrode forming a negative electrode, a plurality of solid electrolytes positioned between the positive electrode and the negative electrode, and a positive electrode formed on one side of a current collector positioned between the adjacent solid electrolytes. A solid battery stack comprising a plurality of bipolar electrodes with negative electrodes formed on opposite surfaces, a positive electrode plate positioned adjacent to the positive electrodes, and a negative electrode plate positioned adjacent to the negative electrodes. and a resin casing that covers the solid battery stack, the positive electrode plate, and the negative electrode plate, and integrates them so that the electrode surfaces of the positive electrode plate and the negative electrode plate are exposed. The resin casing is injected in a resin molding die in a pressurized state that presses the positive electrode plate and the negative electrode plate against the solid battery stack, and is solidified to maintain the pressurized state. and sealing the solid battery stack.

A module structure for an all-solid-state battery according to the present invention, which has been made to achieve the above object, is a module structure for electrically connecting a plurality of casing structures of an all-solid-state battery, wherein the casing structure for the all-solid-state battery comprises: A positive electrode having a positive electrode formed on one side of a current collector, a negative electrode facing the positive electrode and having a negative electrode formed on a side of the current collector facing the positive electrode, and a plurality of electrodes positioned between the positive electrode and the negative electrode. A solid battery stack comprising a solid electrolyte and a plurality of bipolar electrodes positioned between a plurality of adjacent solid electrolytes, each having a positive electrode formed on one side of a current collector and a negative electrode formed on the opposite side of the positive electrode. , a positive electrode plate arranged adjacent to the positive electrode; a negative electrode plate arranged adjacent to the negative electrode; outer peripheral portions of the solid battery stack, the positive electrode plate, and the negative electrode plate; and a resin housing integrated with the positive electrode plate and the negative electrode plate so that the electrode surfaces of the positive electrode plate and the negative electrode plate are exposed, and the resin housing includes the positive electrode plate and the The solid battery stack is sealed while maintaining the pressurized state by being injected and solidified in a pressurized state that presses the negative electrode plate against the solid battery stack, and the housing structure of the plurality of all-solid-state batteries is characterized in that the exposed positive electrode plates are arranged in series adjacent to the exposed negative electrode plates of other all-solid-state battery housing structures.

The positive electrode plate and the negative electrode plate facing each other are connected to each other with a conductive material sandwiched therebetween, and the conductive material is a flexible conductive plate-like member, a conductive film material, or a conductive paste material. Preferably.

According to the case structure of the all-solid-state battery according to the present invention, the positive and negative electrode plates integrated by the resin case sandwiching the solid-state battery stack function as external terminals of the case structure of the all-solid-state battery. By arranging a plurality of positive electrode plates of the housing structure of the all-solid-state battery in series so as to be in contact with the negative electrode plate of the housing structure of another all-solid-state battery, they can be electrically connected in series, It is possible to easily realize a highly space-efficient module structure that does not require an extra connection area. Furthermore, unlike the conventional electrode structure using tabs, since there is no need to connect tabs to each other, man-hours for connection can be reduced.

Further, according to the case structure of the all-solid-state battery according to the present invention, the solid-state battery stack is constrained by sealing the outer peripheral portion with the resin case while being pressed in the stacking direction. It is possible to suppress the expansion of the body in the state of use in which charging and discharging are performed.

According to the module structure using the housing structure of the all-solid-state battery according to the present invention, a conductive plate-like member or a conductive film material having flexibility between the electrode plates of the housing structure of the all-solid-state battery connected in series, Alternatively, since they are connected to each other with a conductive paste material sandwiched between them, the adhesion between the electrode plates of the casing structure of the adjacent all-solid-state battery is improved, the electrical contact resistance is reduced, and the thermal resistance is also reduced. A module structure with excellent electrical and thermal properties can be realized.

1 is a perspective view showing the internal structure by partially cutting the housing structure of an all-solid-state battery according to an embodiment of the present invention; FIG. 2 is a schematic horizontal cross-sectional view of the internal structure of the housing structure of the all-solid-state battery shown in FIG. 1; FIG. Fig. 3 schematically shows a module structure according to an embodiment of the present invention; 4 is a diagram schematically showing the internal structure of the module structure shown in FIG. 3 in a horizontal section; FIG. Fig. 3 schematically illustrates a method of fastening a modular structure according to an embodiment of the present invention; FIG. 6 is a diagram schematically showing the internal structure of the module structure shown in FIG. 5 in a horizontal section;

Next, a specific example of a form for implementing a housing structure of an all-solid-state battery and a module structure using the same according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing the internal structure by partially cutting the housing structure of an all-solid-state battery according to one embodiment of the present invention.

Referring to FIG. 1, a housing structure 1 for an all-solid-state battery according to an embodiment of the present invention includes a solid-state battery stack 20 for charging and discharging, a positive electrode plate 30 and a negative electrode plate 30 sandwiching the solid-state battery stack 20 . It includes an electrode plate 40, and a resin casing 50 that covers the solid battery stack 20, the positive electrode plate 30, and the negative electrode plate 40, and integrates the whole.

The positive electrode plate 30 and the negative electrode plate 40 are exposed to the outside except for the outer peripheral portion covered with the resin housing 50 on one side, and the exposed portion functions as an electrode surface to the outside. That is, the entire solid-state battery housing structure 1 is formed as a substantially rectangular parallelepiped. The exposed electrode surface of the negative electrode plate 40 serves as a negative electrode, and the positive electrode and the negative electrode serve as external terminals of the housing structure 1 of the all-solid-state battery.

FIG. 2 is a diagram schematically showing the internal structure of the housing structure of the all-solid-state battery shown in FIG. 1 by a horizontal cross section.
Referring to FIG. 2, the solid battery stack 20 includes a positive electrode 23 having a positive electrode 22 formed on one side of a current collector 21, a positive electrode 23 located on the opposite side of the positive electrode 23, and a surface of the current collector 21 facing the positive electrode 22. A negative electrode 25 forming a negative electrode 24, a plurality of solid electrolytes 26 positioned between the positive electrode 23 and the negative electrode 25, and a plurality of adjacent solid electrolytes 26 positioned on one side of the current collector 21, respectively. It comprises a plurality of bipolar electrodes 27 forming positive electrodes 22 and forming negative electrodes 24 on the surface opposite to the positive electrodes 22 .

As described above, the solid battery laminate 20 is configured by laminating a plurality of layers. It has a structure in which multiple arrays are arranged in
The materials used for the solid-state battery stack 20 are not limited in kind and combination as long as they function as solid-state batteries. The following known materials are used for each layer of the solid battery stack 20 .

A metal foil is generally used for the current collector 21, and materials such as Al, SUS, Cu, and Ni are used as materials for the metal foil. The solid battery stack 20 includes current collectors 21 for three types of electrodes, a positive electrode 23, a negative electrode 25, and a bipolar electrode 27, and the materials of the three types of electrodes may be the same or different.

The positive electrode 22 contains a positive electrode active material such as LiCoO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiFePO ₄ , LiMnPO ₄ and the like. The positive electrode is included in the positive electrode 23 and the bipolar electrode 27, and it is preferable that the positive electrode 23 and the bipolar electrode 27 use the same positive electrode active material.

The negative electrode 24 contains a negative electrode active material, and carbon materials such as graphite, hard carbon, and soft carbon, and inorganic oxides such as Li ₄ Ti ₅ O ₁₂ are used as the negative electrode active material. The negative electrode is included in the negative electrode 25 and the bipolar electrode 27, and it is preferable that the negative electrode 25 and the bipolar electrode 27 use the same negative electrode active material.

As a material for the _solid electrolyte 26, an oxide-based _solid electrolyte or a sulfide _- based solid electrolyte _{is used} . _0.5 La _0.5 TiO ₃ and the like, and sulfide-based solid electrolytes include Li ₂ SP ₂ S ₅ , Li ₂ S—SiS ₂ , LiGe _0.25 P _0.75 S ₄ and the like. mentioned.

In addition to the solid battery stack 20, a positive electrode plate 30 is arranged adjacent to the outer surface of the positive electrode 23, a negative electrode plate 40 is arranged adjacent to the outer surface of the negative electrode 25, and the solid battery stack 20, The outer peripheral portions of the positive electrode plate 30 and the negative electrode plate 40 are covered with a resin housing 50 and integrated. At this time, the portions of the positive electrode plate 30 and the negative electrode plate 40 covered with the resin housing 50 are partially covered so that the resin housing 50 covering the outer peripheral portion does not protrude higher than the electrode surfaces of the positive electrode plate 30 and the negative electrode plate 40. It has a thin step structure.

The positive electrode plate 30 and the negative electrode plate 40 are made of a material having good thermal conductivity in addition to electrical conductivity, such as a metallic material. The exposed electrode surface may be subjected to surface treatment such as plating for improving corrosion resistance and keeping contact resistance low.
The resin casing 50 is formed by injecting it into a mold and curing it as described below, and uses a thermosetting resin. The resin housing 50 is for putting together the housing structure 1 of the all-solid-state battery as a structural body, and is required to have strength and environmental resistance. Therefore, a thermosetting resin such as an epoxy sealing material is used.

When forming the housing structure 1 of the all-solid-state battery shown in FIGS. , The mold is placed in a mold, and when the mold is clamped, the depth of the mold is adjusted so that pressure is applied to the combined structure in the stacking direction. The mold resin is injected into the outer periphery and cured in the mold.

By resin-sealing in a pressurized state in this way, it is possible to reduce the contact resistance between the positive electrode plate 30, the solid battery stack 20, and the negative electrode plate 40, and prevent deterioration in battery performance. . Further, by solidifying the solid battery stack 20 so as to be held in a pressurized state by the resin casing, it is possible to suppress expansion of the solid battery stack 20 during charging and discharging.

The solid battery stack 20 is covered with the positive electrode plate 30 and the negative electrode plate 40 on the front and back surfaces, and is covered with the resin housing 50 on the outer periphery, so that it is shielded from the outside air and can be prevented from being deteriorated by moisture or foreign matter during use. It is possible. In addition, by making the positive electrode plate 30 and the negative electrode plate 40 thick, it is possible to prevent the solid battery stack 20 from being damaged even if a mechanical external force is applied, and an effect of improving safety can be obtained. be done.

When the resin is injected into the molding die, if the positive electrode 22 or the negative electrode 24 is larger than the solid electrolyte 26 and protrudes outside the solid electrolyte 26, the injected resin deforms the positive electrode 22 and the negative electrode 24 so that the positive electrode 22 and the negative electrode 24 approach or contact each other. The positive electrode 22 and the negative electrode 24 are formed smaller than the solid electrolyte 26, because this leads to a short circuit and a decrease in reliability.

FIG. 3 is a schematic diagram of a module structure according to an embodiment of the present invention.
Referring to FIG. 3, a module structure 10 according to an embodiment of the present invention has a form in which a plurality of casing structures 1 of all-solid-state batteries shown in FIG. 1 are connected in series. The case structure 1 of the all-solid-state battery has a substantially rectangular parallelepiped shape, but the exposed positive electrode plate 30 of one of the adjacent case structures 1 of the all-solid-state battery is the exposed negative electrode plate 30 of the other case structure 1 of the all-solid-state battery. The electrode plates are arranged in series adjacent to each other.

FIG. 3 shows a structure in which six all-solid-state battery housing structures 1 are arranged in series. By connecting as described above, the positive electrode plate 30 of the first all-solid-state battery housing structure 1 The sixth negative electrode plate 40 serves as the positive electrode of the module structure 10 and the negative electrode of the module structure 10 . The number of casing structures 1 for all-solid-state batteries included in the module structure 10 is not limited to six, and may be more or less than six. Regardless of the number of stacks, the positive electrode plate 30 of the first all-solid-state battery housing structure 1 becomes the positive electrode of the module structure 10, and the last all-solid-state battery housing structure 1 of the negative electrode plate 40 becomes the module structure. 10 negative electrodes.

As described above, in the case structure 1 of the all-solid-state battery according to the present invention, tabs serving as external terminals do not protrude from the solid-state battery stack 20 unlike conventional all-solid-state batteries. It is not necessary to separately provide a connection area for connecting the body structures 1, and it is possible to realize a module structure with high space efficiency.

FIG. 4 is a diagram schematically showing the internal structure of the module structure shown in FIG. 3 in horizontal section.
As described above, since the resin casing 50 does not protrude higher than the electrode surfaces of the positive electrode plate 30 and the negative electrode plate 40, it is possible to realize an electrically series-connected module structure by simply arranging them in series. If the electrode surfaces of the positive electrode plate 30 and the negative electrode plate 40 have minute irregularities or inclinations, the contact resistance between the positive electrode plate 30 and the negative electrode plate 40 may increase.

Therefore, in the module structure shown in FIG. 4, the positive electrode plate 30 and the negative electrode plate 40 facing each other in the casing structure 1 of the adjacent all-solid-state battery are connected to each other with the conductive material 60 interposed therebetween. Here, the conductive material 60 is a flexible conductive plate member, a conductive film material, or a conductive paste material. Conductive materials with such flexibility generally have conductive microparticles dispersed at a high density. It is configured. The conductive material 60 may be applied to such conductive fine particles, or the material itself may have conductivity and deformability.

When the positive electrode plate 30 and the negative electrode plate 40 facing each other with a flexible conductive plate member, conductive film material, or conductive paste material sandwiched therebetween are pressed in the direction of approaching each other, the electrode surfaces The positive electrode plate 30 and negative electrode plate 40 can be prevented from increasing.

FIG. 5 is a diagram schematically showing a fastening method of a module structure according to an embodiment of the present invention, and FIG. 6 is a diagram schematically showing the internal structure of the module structure shown in FIG. 5 in horizontal section.
In order to form a module structure 10 by connecting a plurality of all-solid-state battery casing structures 1 in series, adjacent all-solid-state battery casing structures 1 must be pressed against each other and fixed from the viewpoint of contact resistance. is desirable. Figures 5 and 6 show one embodiment of a fastening method for this purpose.

5 and 6, a pair of fasteners 70 are provided laterally along the direction in which the plurality of all-solid-state battery housing structures 1 are arranged in series, and the plurality of all-solid-state battery housing structures 1 are arranged sideways. are fixed to the fastening body 70 by fastening bolts 71 . The fastener 70 is bent downward into an L-shape and has legs with bolt holes for attachment, and is adapted to be attached to the housing of the device or vehicle that uses the module structure 10 .

5 and 6, the module structure 10 shown in FIGS. The body structure 1 is fixed by the fastening bolt 71 while being pressed against the housing structure 1 of the first all-solid-state battery. A module structure 10 that prevents an increase in resistance can be formed. At this time, a conductive material 60 as shown in FIG. 4 may be sandwiched for connection. Further, the bolt holes through which the fastening bolts 71 of the fastening body 70 pass may be formed as long holes so that the mounting position of the housing structure 1 of the all-solid-state battery can be adjusted.

The housing structure 1 of the all-solid-state battery used in the module structure 10 shown in FIG. has a screw mount.
In another embodiment, a notch is provided in the solid battery stack 20 at the portion to which the fastening bolt 71 is fastened, and a screw mounting portion is provided so as to fit in the notch so as not to generate a protrusion on the side surface. shape.
The shape of the fastening body 70 shown in FIGS. 5 and 6 and the fastening method using the fastening body 70 are one embodiment. is not limited to

Although the embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the technical scope of the present invention. It is possible to

1 Case Structure of All Solid Battery 10 Module Structure 20 Solid Battery Stack 21 Current Collector 22 Positive Electrode 23 Positive Electrode 24 Negative Electrode 25 Negative Electrode 26 Solid Electrolyte 27 Bipolar Electrode 30 Positive Electrode Plate 40 Negative Electrode Plate 50 Resin Case 60 Conductivity elastic material 70 fastening body 71 fastening bolt

Claims (1)

A module structure that electrically connects a plurality of housing structures of all-solid-state batteries,
The housing structure of the all-solid-state battery is
A positive electrode having a positive electrode formed on one side of a current collector, a negative electrode facing the positive electrode and having a negative electrode formed on a side of the current collector facing the positive electrode, and a plurality of electrodes positioned between the positive electrode and the negative electrode. A solid battery stack comprising a solid electrolyte and a plurality of bipolar electrodes positioned between a plurality of adjacent solid electrolytes, each having a positive electrode formed on one side of a current collector and a negative electrode formed on the opposite side of the positive electrode. ,
a positive electrode plate positioned adjacent to the positive electrode;
a negative electrode plate positioned adjacent to the negative electrode;
a resin casing that covers outer peripheral portions of the solid battery stack, the positive electrode plate, and the negative electrode plate, and integrates the positive electrode plate and the negative electrode plate so that electrode surfaces of the positive electrode plate and the negative electrode plate are exposed; death,
The resin casing is injected in a resin mold in a pressurized state that presses the positive electrode plate and the negative electrode plate against the solid battery stack and is solidified, thereby maintaining the pressurized state and solidifying the solid state. sealing the battery stack,
the plurality of all-solid-state battery housing structures are arranged in series such that exposed positive electrode plates are adjacent to exposed negative electrode plates of other all-solid-state battery housing structures ;
The positive electrode plate and the negative electrode plate facing each other are connected to each other with a conductive material interposed therebetween,
A module structure, wherein the conductive material is a flexible conductive plate member, a conductive film material, or a conductive paste material.

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