JP7259691B2 - laminate structure - Google Patents

Description

The present invention relates to laminate structures.

From the viewpoint of weight reduction and space saving, there is a technique of sealing an electrode body, which is a laminate of battery elements such as a positive electrode, a negative electrode, and a separator, with a laminate film. Sealing with a laminate is also being considered for an all-solid-state battery that uses a solid electrolyte.

For example, when a sulfide-based solid electrolyte is used for the electrode body, there is concern that harmful sulfide-based gas may be generated. When such gas is generated inside the laminate film, pressure is applied to the sealed portion, and the gas leaks out when the sealed portion is cleaved.

Patent Literature 1 discloses that a water absorbing member is disposed apart from the battery element, and the water absorbing member is provided inside the laminated exterior body. However, it is difficult to detect gas leakage from the welded portion.

Patent Literature 2 discloses a structure in which a laminate expands due to gas generation inside a battery and contacts a sensor to detect gas generation. However, gas leakage cannot be detected if the sealing portion is ruptured before contact with the sensor.

JP 2003-187762 A Japanese Patent Application Laid-Open No. 2003-168410

The main object of the present application is to provide a laminate structure that can easily detect the generation of gas before the gas generated inside flows out to the outside.

As one means for solving the above-described problems, the present application provides a laminate structure that is an electrode exterior body, wherein an unsealed portion formed between sealed portions has a gas flow path portion and a gas reservoir portion. The width of the gas reservoir is greater than the width of the gas flow path, the gas reservoir is shorter than the gas flow path, and the volume ratio obtained by dividing the volume of the gas reservoir by the volume of the gas flow path is 2 or more. A laminate structure is disclosed.

According to the laminate structure disclosed by the present application, it is possible to easily detect gas generation before the internally generated gas flows out to the outside.

It is a figure explaining the structure of the all-solid-state battery containing the laminate structure of this application.

The laminate structure of the present invention will be described in detail below. FIG. 1 is a diagram illustrating the structure of an all-solid laminate battery. The all-solid laminate battery 10 has a laminate structure 11 and an electrode assembly 21 .

[Laminate structure]
The laminate structure 11 functions as an exterior body for the electrode body 21, and is a structure in which laminate films are superimposed and the outer peripheral portion thereof is sealed.
The laminate structure 11 has a hollow storage portion 12 in which the electrode body 21 is stored, and a first sealing portion, which is a sealing portion, is provided on the outer peripheral side of the storage portion 12 so as to surround the storage portion 12. 13. A gas channel portion 14 and a gas pool portion 15, which are unsealed portions (non-sealed portions), are provided on the outer peripheral side of the first sealing portion 13, and the gas channel portion 14 and the gas pool portion are provided. A second sealing portion 16 that is a sealing portion is formed on the outer peripheral side of 15 .
In this way, the laminate structure 11 has a first sealed portion 13, a non-sealed portion (the gas flow path portion 14 and the gas reservoir portion 15), and a second sealed portion from the storage portion 12 toward the outer peripheral side. It has a structure in which 16 are lined up. Further, the gas passage portion 14 and the gas reservoir portion 15 are communicated with each other.

A known laminate film can be used for the laminate structure.

<Gas Flow Path Portion 14 and Gas Reservoir Portion 15>
The unsealed portion has a gas flow path portion 14 and a gas reservoir portion 15, both sides of which are sealed by a first sealing portion 13 and a second sealing portion 16, forming two sealing portions. Since it is sandwiched between the stop portions, it forms a channel or a cavity when gas flows into it. Therefore, the gas does not flow out to the outside at least immediately, but flows and accumulates in the gas flow path portion 14 and the gas reservoir portion 15 .

The shapes of the gas flow path portion 14 and the gas reservoir portion 15 have the following characteristics.
When the width of the gas passage portion 14 is W _R and the length is L _R , and the width of the gas reservoir portion 15 is W _T and the length is L _T , the following relationship holds.
W _R <W _T and L _R >L _T

The width W _R of the gas channel portion 14 is the size in the direction perpendicular to the direction in which the channel extends, and the length L _R is the total length of the gas channel portion 14 along the direction in which the channel extends.
On the other hand, the width W _T of the gas pool portion 15 is the width of the portion of the gas passage portion 14 adjacent to the gas pool portion 15 that is the largest in the same direction. The length _LT of the gas pool portion 15 is the size in the same direction as the direction in which the portion of the gas channel portion 14 adjacent to the gas pool portion 15 extends.

Furthermore, when the maximum volume that the gas passage portion 14 can take is V _R and the maximum volume that the gas reservoir portion 15 can take is V _T , the volume ratio R preferably satisfies the following relationship.
R= _VT / _VR ≧2
As a result, as will be described later, the height of the gas reservoir can be made sufficient with respect to the inflow of gas into the unsealed portion, and the generation of gas can be easily detected.

Note that the shape of the gas reservoir 15 from the viewpoint shown in FIG. 1 is not limited to being rectangular as in the present embodiment, and square, circular, elliptical, and other geometric shapes can be applied.
Further, the number of gas reservoirs is not limited to one, and a plurality of gas reservoirs may be arranged.

[Electrode body]
The electrode body 21 is each element constituting the all-solid-state battery in this embodiment, and includes, for example, a positive electrode active material layer, a negative electrode active material layer, a solid electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer, A positive electrode current collector and a negative electrode current collector are provided.

<Positive electrode active material layer>
The positive electrode active material layer is a layer containing at least a positive electrode active material, and if necessary, may contain at least one of a solid electrolyte material, a conductive material and a binder.

The positive electrode _active material _is not particularly limited _{, and} known materials can be _{used .} O3 _, etc.), iron phosphate-based ( _LiFePO4 , _{Li2FeP2O7 ,} etc.), NCA-based (nickel, _cobalt and aluminum compounds), NMC-based (nickel, manganese and cobalt compounds), and the like.

The solid electrolyte material is not particularly limited, but includes a sulfide solid electrolyte material and an oxide solid electrolyte material.
Examples of sulfide solid electrolyte materials having Li ion conductivity include Li ₂ SP ₂ S ₅ , Li ₂ SP ₂ S ₅ -LiI, Li ₂ SP ₂ S ₅ -Li ₂ O, Li ₂ S—P ₂ S ₅ —Li ₂ O—LiI, Li ₂ S—SiS ₂ , Li ₂ S—SiS ₂ —LiI, Li ₂ S—SiS ₂ —LiBr, Li ₂ S—SiS ₂ —LiCl, Li _2S - _SiS2 - _{B2S3 -} LiI, _{Li2S -SiS2-P2S5 - LiI} , _Li2S - _{B2S3 ,} Li2S- _{P2S5 -} ZmSn (where m, n is a positive number, and Z is one of Ge, Zn, and Ga.), Li ₂ S—GeS ₂ , Li ₂ S—SiS ₂ —Li ₃ PO ₄ , Li ₂ S—SiS ₂ —Li _x MO _y ( However, x and y are positive numbers, and M is any one of P, Si, Ge, B, Al, Ga, and In.). The above description of "Li ₂ SP ₂ S ₅ " means a sulfide solid electrolyte material using a raw material composition containing Li ₂ S and P ₂ S ₅ .
On the other hand, examples of oxide solid electrolyte materials having Li ion conductivity include compounds having a NASICON structure. Examples of compounds having a NASICON structure include compounds represented by the general formula Li _1+x Al _x Ge _2-x (PO ₄ ) ³ (0≦x≦2) (LAGP) and general formula Li _1+x Al _x Ti _{2 -x} (PO ₄ ) ³ (0≦x≦2) (LATP) and the like. Other examples of oxide solid electrolyte materials include LiLaTiO (eg, Li _0.34 La _0.51 TiO ₃ ), LiPON (eg, Li _2.9 PO _3.3 N _0.46 ), LiLaZrO ( For _example , _Li7La3Zr2O12 ) etc. can _be mentioned _.

The addition of the conductive material can improve the electron conductivity of the positive electrode active material layer. The conductive material is not particularly limited, and may include known carbon materials and metal materials.
The binder is not particularly limited as long as it is chemically and electrically stable. Examples include rubber-based binders such as butadiene rubber (SBR), olefin-based binders such as polypropylene (PP) and polyethylene (PE), and cellulose-based binders such as carboxymethylcellulose (CMC).

<Negative electrode active material layer>
The negative electrode active material layer is a layer containing at least a negative electrode active material, and if necessary, may contain at least one of a solid electrolyte material, a conductive material and a binder. The solid electrolyte material, conductive material and binder can be considered in the same manner as the positive electrode active material layer.

Examples of negative electrode active materials include metal active materials and carbon active materials. Examples of metal active materials include In, Al, Si and Sn. On the other hand, examples of carbon active materials include mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon.

<Solid electrolyte layer>
The solid electrolyte layer is a layer formed between the positive electrode active material layer and the negative electrode active material layer. The solid electrolyte layer contains at least a solid electrolyte material. Examples of the solid electrolyte material include a sulfide solid electrolyte material and an oxide solid electrolyte material, which can be considered in the same manner as the materials described above for the positive electrode active material layer.

<Current collector>
The current collectors are a positive electrode current collector laminated on the positive electrode active material layer and collecting current, and a negative electrode current collector laminated on the negative electrode active material layer and collecting current. Examples of materials for the positive electrode current collector include stainless steel, aluminum, nickel, iron, titanium and carbon. On the other hand, examples of materials for the negative electrode current collector include stainless steel, copper, nickel and carbon.

<Terminal>
Further, as shown in FIG. 1, terminals 22 are connected to the current collector to enable connection with the outside.

[Fabrication of laminated all-solid-state battery]
Production of the laminated all-solid-state battery is not particularly limited, but is carried out, for example, as follows.
The electrode body 21 is arranged between two laminate films, and the outer periphery of the electrode body 21 is first vacuum-sealed to form a first sealing portion. Next, the outside of the first sealing portion is vacuum-sealed so as to leave the unsealed portion (the gas flow path portion and the gas reservoir portion) to form the second sealing portion.

[Action]
According to the laminate structure as described above, when gas is generated in the electrode body 21 and the sealing of the first sealing portion is broken, the gas is released to the gas flow path portion 14, which is the unsealed portion, and the gas It flows into the reservoir 15 . Here, since the gas reservoir 15 has the characteristics as described above with respect to the gas flow path 14, the gas directly and preferentially flows into the gas reservoir 15 from the storage 12, and the gas reservoir 15 does not flow into the gas reservoir 15. Gas flows into the portion 15 from the gas flow path portion 14 . As a result, the gas reservoir 15 swells with good response, and the height (the size in the thickness direction of the laminate film) changes.

The laminate film structure of the present disclosure will be described below using examples. In the examples, the volume ratio R was varied to evaluate the height of the gas reservoir during gas generation.

[Electrode body]
For the positive electrode active material layer, an NCM (nickel, cobalt, manganese)-based positive electrode active material and an S-based solid electrolyte were used, and the binder was polyvinylidene fluoride (PVDF).
For the negative electrode active material layer, a Si-based negative active material and an S-based solid electrolyte were used, and styrene-butadiene rubber (SBR) was used as a binder.
The solid electrolyte layer (separator) was an S-based solid electrolyte.

[Laminated film structure]
The electrode body is stored in the storage part, and non-sealed parts (gas flow path part, gas reservoir part) such as Examples 1 to 2 and Comparative Examples 1 to 3 are formed to form a solid Battery.
(Example 1)
In Example 1, the width of the gas passage portion is 1 mm, the total length of the gas passage portion is 200 mm, the width of the gas reservoir portion is 5 mm, and the length of the gas reservoir portion is 80 mm. The volume of the gas channel portion/the volume of the gas channel portion) was set to 2.
(Example 2)
In Example 2, the volume ratio R was set to 5 by changing the width of the gas reservoir.
(Comparative example 1)
In Comparative Example 1, the width of the gas reservoir was changed to set the volume ratio R to 1.5.
(Comparative example 2)
In Comparative Example 2, the volume ratio R was set to 1 by changing the width of the gas reservoir.
(Comparative Example 3)
In Comparative Example 3, no second sealing portion was formed.

[Evaluation method]
For each example, gas was generated from the electrode assembly, and the height of the gas reservoir (the size in the thickness direction of the laminate film) at that time was measured, and the outflow of the gas to the outside was inspected.
As for the height of the gas reservoir, the height at which appropriate detection was possible was obtained in Example 1, so this was used as a reference, and in the other examples, the ratio of the height of the object example to the height in Example 1 was used. (The height of the target example was divided by the height of Example 1.). Table 1 shows the results.

As can be seen from Table 1, when the volume ratio R is 2 or more, the height of the gas reservoir is sufficiently secured for gas generation, and prompt detection can be performed.

10 All-solid-state battery 11 Laminate structure 12 Storage part 13 First sealing part 14 Gas flow path part (non-sealing part)
15 gas reservoir (unsealed portion)
16 second sealing part 21 electrode body 22 terminal

Claims (1)

A laminated structure that is an electrode outer package and in which laminated films are superimposed and the outer peripheral portion is sealed ,
a hollow storage portion in which the electrode assembly is stored;
a first sealing portion surrounding the storage portion;
a non-sealed portion provided so as to surround the outer peripheral side of the first sealed portion;
a second sealing portion provided so as to surround the outer peripheral side of the non-sealing portion;
The non-sealed portion has a gas flow path and a gas reservoir provided in communication with the gas flow path and adjacent to the gas flow path ,
When the direction in which the unsealed portion extends so as to surround the first sealed portion is taken as the length direction, and the direction perpendicular to this in which the first sealed portion and the unsealed portion are aligned is taken as the width direction ,
the gas reservoir is a portion having a width greater than that of the gas channel,
The gas reservoir is shorter than the gas flow path, and the volume ratio obtained by dividing the volume of the gas reservoir by the volume of the gas flow path when the gas is accumulated is 2 or more,
When the sealing of the first sealing portion is broken, gas flows into the gas reservoir and the gas reservoir expands, and the height of the gas reservoir is the size in the thickness direction of the laminate film. changes,
laminate structure.

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