JP2019169312A - All-solid battery - Google Patents

Abstract

To provide an all-solid battery, and the all-solid battery in which the contact with an outer member such as a battery case or the like housing the all-solid battery at the time of charging is suppressed.SOLUTION: An all-solid battery 100 of the present invention has at least one unit all-solid battery, and the unit all-solid battery includes: a positive electrode collector layer; a positive active material layer; a solid-electrolyte layer; a negative active material layer; and a negative electrode collector layer in this order. The all-solid battery includes a substantially rectangular outer peripheral shape made from two long sides 10 opposite each other and two short sides 20 opposite each other in a surface direction. Each of the two long sides exists so as to be cross a region near an intersection point 42 of a substantially rectangular diagonal line 40 from a line connecting each of both ends 30 in respective long sides. Thus, the length in the short side direction in a central part 50 of the all-solid battery is formed so as to be shorter than that of the two short sides.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an all solid state battery.

  As a power source for driving an electric motor of a hybrid vehicle or the like, an all solid state battery such as an all solid state lithium ion battery has attracted attention. Such an all-solid battery comprises at least one unit all-solid battery, wherein the unit all-solid battery comprises a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and It has a negative electrode collector layer in this order.

  Patent Document 1 includes a positive electrode including a positive electrode active material, a negative electrode including a negative electrode active material, and a solid electrolyte interposed between the positive electrode and the negative electrode, and has a substantially rectangular parallelepiped shape. A pair of chamfered shapes and R-chamfered shapes provided on the portion, and a pair of layers disposed at both ends of the laminate so as to sandwich the side surfaces of the laminate and connected to one of the positive electrode and the negative electrode, respectively An all-solid lithium secondary battery comprising an external current collector is disclosed.

  Patent Document 2 discloses a non-aqueous electrolyte battery that includes a base portion that is formed of a metal foil and has an electrode layer formed on at least one surface to form an electrode body, and a current collecting lead portion that is drawn from the base portion. A current collector, in which a base portion and a lead portion are integrally formed. The base portion includes a film formation region in which an electrode layer is formed and a film formation region from the outer peripheral edge to the inside of the base portion. A surplus region having a width of 1.5 mm or less, and the surplus region has a plurality of notches for positioning with respect to a current collector holder that holds the current collector during film formation, A current collector for a non-aqueous electrolyte battery is disclosed.

  Patent Document 3 discloses a laminate for an all-solid battery in which a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer are laminated in this order, and at least a part of the end of the laminate is chamfered. A laminate for an all-solid-state battery is disclosed.

JP 2007-080812 A JP2011-198625A Japanese Patent Application Laid-Open No. 2015-0500153

  In the all solid state battery having the unit all solid state battery, the expansion amount of the central portion is larger than the expansion amount of both end portions in the plane direction due to the non-uniform expansion of the active material layer during charging. Due to such non-uniform expansion, an external member such as a battery case housing the all-solid battery is brought into contact with the central portion of the all-solid battery, which may deteriorate the performance of the all-solid battery. This expansion was particularly noticeable when an alloy-based negative electrode was used as the negative electrode active material.

  Therefore, there is a need to provide an all solid state battery in which contact between the all solid state battery and an external member such as a battery case storing the all solid state battery is suppressed.

As a result of intensive studies, the present inventors have found that the above problems can be solved by the following means, and have completed the present invention. That is, the present invention is as follows:
<Aspect 1> An all-solid battery having at least one unit all-solid battery,
The unit all solid state battery has a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order,
The all-solid-state battery has a substantially rectangular outer peripheral shape composed of two long sides facing each other and two short sides facing each other in the surface direction, and the two long sides Each of the sides exists so as to cross a region closer to the intersection of the substantially rectangular diagonal lines than a line segment connecting both ends of each of the long sides, thereby, in the central portion of the all solid state battery. The length in the short side direction is shorter than any of the two short sides,
All solid battery.

  ADVANTAGE OF THE INVENTION According to this invention, the all-solid-state battery with which the contact at the time of charge with an all-solid-state battery and external members, such as a battery case which accommodates it was suppressed can be provided.

FIG. 1 is a conceptual diagram of an all-solid battery of the present invention. FIG. 2 is a conceptual diagram of the all solid state battery of the present invention before and after charging. FIG. 2 (a) shows a state before charging, and FIG. 2 (b) shows a state after charging. FIG. 3 is a conceptual diagram of a conventional all solid state battery before and after charging. FIG. 3A shows a state before charging, and FIG. 3B shows a state after charging.

<All-solid battery>
As shown in FIG. 1, an all solid state battery 100 of the present invention is an all solid state battery having at least one unit all solid state battery,
The unit all solid state battery includes a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order.
The all-solid-state battery has a substantially rectangular outer peripheral shape composed of two long sides 10 facing each other and two short sides 20 facing each other in the plane direction, and has two long sides Each of the sides 10 exists so as to cross a region closer to the intersection 42 of the substantially rectangular diagonal line 40 than the line segment connecting the both ends 30 of each long side 10, and thereby the center of the all-solid-state battery. The length of the portion 50 in the short side direction is set to be shorter than any length of the two short sides 20.

  Here, in the present invention, the “substantially square” is a shape in which a straight line connecting each vertex forms a square, and each of the two long sides is more than a line segment connecting both ends of each long side. , And exists so as to cross a region near the intersection of diagonal lines of a substantially rectangular shape, whereby the length in the short side direction at the center of the substantially rectangular shape is shorter than the length of any of the two short sides. In other words, it means a shape different from a square. Such a shape can be obtained, for example, by cutting an all-solid battery laminate using a laser.

  When the all solid state battery is viewed in the plane direction, that is, when the all solid state battery is viewed from the stacking direction of each layer, when the all solid state battery is charged, the all solid state battery expands unevenly. In particular, when the shape of the all-solid battery in the surface direction is the rectangle shown in FIG. 3A, the expansion in the short side direction is large near the center of the all-solid battery as shown in FIG. 3B. Become. It should be noted that the state of expansion is exaggerated to clarify the difference and does not necessarily match the actual scale.

  On the other hand, as shown in FIG. 2A, when the length in the short side direction in the central portion of the all-solid-state battery is shorter than any of the two short sides, the expansion due to charging is performed. 2b, as shown in FIG. 2 (b), it is possible to suppress the departure from the substantially rectangular extension, and as a result, when an external member is disposed on the side surface of the all-solid-state battery, for example, When the solid battery is stored in the battery case, unintentional contact between the all solid battery and the external member can be prevented. In the present invention, the substantially square extension is defined as a square region obtained by connecting the apexes 30 of the substantially square with straight lines.

  Hereinafter, the “substantially rectangular shape” that is the outer peripheral shape in the surface direction of the all solid state battery of the present invention will be described more specifically.

  The length of the substantially square in the short side direction may be the shortest at an arbitrary position in the central portion. As shown in FIG. 1, the central portion 50 has two line segments that are parallel to the short side 20 and separated from the two short sides 20 by a length that is ¼ of the length in the long side direction. 52 and the area surrounded by two long sides.

  The length in the short side direction at the position where the length in the short side direction is the shortest is 99.8% or less, 99.5% or less, 99.3% or less, or 99 of the length of the two short sides. 0.0% or less is preferable from the viewpoint of making it difficult to deviate the substantially rectangular extension during charging. The length in the short side direction is 97.0% or more, 97.5% or more, or 98.0% or more of the length of the two short sides, from the viewpoint of not impairing the battery capacity excessively. preferable. As shown in FIG. 1, the length in the short side direction may coincide with the length of a line segment 12a that connects the midpoints 12 of the two long sides 10 in a substantially square shape, for example.

  The two long sides may each be constituted by a pair of continuous curves or straight lines having no inflection points extending from both ends of the long side to the position where the length in the short side direction is the shortest. In particular, when the long side is composed of a pair of curves, these curves may form a continuous curve with no inflection point as a unit.

  As shown in FIG. 1, the two long sides may be symmetric with respect to the long axis 60, which is a line segment connecting the midpoints of the short sides, or may be asymmetric, but are symmetric. It is preferable from the viewpoint of ease of manufacture.

  Next, each layer which comprises the laminated body for all-solid-state batteries in the all-solid-state battery of this invention is demonstrated.

  In the present invention, the “positive electrode current collector layer” referred to below means that at least one surface is in contact with the positive electrode active material layer, and only the positive electrode active material layer is present. The current collector layer may be in contact, or may be a current collector layer that can be shared by the positive electrode active material layer and the negative electrode active material layer. Similarly, the “negative electrode current collector layer” referred to below may be a current collector layer in contact with only the negative electrode active material layer, or a current collector that can be shared by the positive electrode active material layer and the negative electrode active material layer. It may be an electrical layer.

<Positive electrode current collector layer>
The conductive material used for the positive electrode current collector layer is not particularly limited, and any known material that can be used for an all-solid battery can be appropriately employed. Examples include stainless steel (SUS), aluminum, copper, nickel, iron, titanium, and carbon.

  The shape of the positive electrode current collector layer according to the present disclosure is not particularly limited, and examples thereof include a foil shape, a plate shape, and a mesh shape. Among these, a foil shape is preferable.

<Positive electrode active material layer>
The positive electrode active material layer contains at least a positive electrode active material, and preferably further includes a solid electrolyte described later. In addition, an additive used for a positive electrode active material layer of an all-solid battery, such as a conductive additive or a binder, can be included in accordance with the intended use or intended purpose.

In the present disclosure, the positive electrode active material used is not particularly limited, and a known material is used. For example, sulfur (S), lithium sulfide (Li ₂ S), lithium cobaltate (LiCoO ₂ ), lithium nickelate (LiNiO ₂ ), lithium manganate (LiMn ₂ O ₄ ), LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , Li _{1 + x} Mn _2−xy M _y O ₄ (M is one or more metal elements selected from Al, Mg, Co, Fe, Ni, and Zn) Examples include, but are not limited to, heteroelement-substituted Li—Mn spinel.

  The conductive auxiliary agent is not particularly limited, and known ones are used. Examples thereof include, but are not limited to, carbon materials such as VGCF (vapor-grown carbon fiber, Vapor Carbon Carbon Fiber) and carbon nanofibers, and metal materials.

  It does not specifically limit as a binder, A well-known thing is used. Examples include, but are not limited to, materials such as polyvinylidene fluoride (PVdF), carboxymethylcellulose (CMC), butadiene rubber (BR), styrene butadiene rubber (SBR), or combinations thereof.

<Solid electrolyte layer>
The solid electrolyte layer includes at least a solid electrolyte. The solid electrolyte is not particularly limited, and a material that can be used as a solid electrolyte of an all-solid battery can be used. For example, a sulfide solid electrolyte, an oxide solid electrolyte, a polymer electrolyte, or the like can be used.

Examples of the sulfide solid electrolyte include, for example, Li ₂ S—SiS ₂ , LiI—Li ₂ S—SiS ₂ , LiI—Li ₂ S—P ₂ S ₅ , LiI—LiBr—Li ₂ S—P ₂ S ₅ , _{Li 2 S-P 2 S 5} -LiI-LiBr, Li 2 S-P 2 S 5 -GeS 2, LiI-Li 2 S-P 2 O 5, LiI-Li 3 PO 4 -P 2 S 5, and Li ₂ S-P ₂ S _{5 and the} like; sulfide-based crystalline solid electrolytes such as Li ₁₀ GeP ₂ S ₁₂ , Li ₇ P ₃ S ₁₁ , Li ₃ PS ₄ , and Li _3.25 P _0.75 S ₄ As well as combinations thereof.

Examples of oxide solid electrolytes include Li ₂ O—B ₂ O ₃ —P ₂ O ₃ , Li ₂ O—SiO ₂ , Li ₂ O—P ₂ O _{5 and} other oxide amorphous solid electrolytes, Li ₅ La ₃ Ta ₂ O ₁₂ , Li ₇ La ₃ Zr ₂ O ₁₂ , Li ₆ BaLa ₂ Ta ₂ O ₁₂ , Li ₃ PO _{(4-3 / 2w)} N _w (w <1), Li _3.6 Si _0.6 Examples thereof include, but are not limited to, oxide crystalline solid electrolytes such as P _0.4 O ₄ .

  The sulfide solid electrolyte or oxide solid electrolyte may be glass or crystallized glass (glass ceramic).

  Examples of the polymer electrolyte include, but are not limited to, polyethylene oxide (PEO) and polypropylene oxide (PPO).

  Further, the solid electrolyte layer may contain a binder or the like as necessary in addition to the above-described solid electrolyte. A specific example is the same as the “binder” listed in the “positive electrode active material layer” described above, and a description thereof is omitted here.

<Negative electrode active material layer>
The negative electrode active material layer includes at least a negative electrode active material, and preferably further includes the solid electrolyte described above. In addition, an additive used for the negative electrode active material layer of the all-solid-state battery, such as a conductive additive or a binder, can be included in accordance with the intended use or intended purpose.

  In the present disclosure, the negative electrode active material used is not particularly limited as long as it can occlude and release metal ions such as lithium ions. Examples include, but are not limited to, metals such as Li, Sn, Si, or In, alloys of lithium and titanium, or carbon materials such as hard carbon, soft carbon, or graphite.

  Among these, as a negative electrode active material, an alloy-based negative electrode active material containing two or more metals selected from the group consisting of Li, Sn, Si, In, and Ti, particularly an alloy-based negative electrode containing Si When the active material is used as the negative electrode active material, the configuration of the present invention is more useful because the all solid state battery is easily expanded by charging.

  As other additives such as a solid electrolyte, a conductive additive, and a binder used in the negative electrode active material layer, those described in the above-mentioned items of “positive electrode active material layer” and “solid electrolyte layer” can be appropriately employed. .

<Negative electrode current collector layer>
The conductive material used for the negative electrode current collector layer is not particularly limited, and a known material that can be used for an all-solid battery can be appropriately employed. Examples include stainless steel (SUS), aluminum, copper, nickel, iron, titanium, and carbon.

  The shape of the negative electrode current collector layer according to the present disclosure is not particularly limited, and examples thereof include a foil shape, a plate shape, and a mesh shape. Among these, a foil shape is preferable.

10 Long side 12 Mid point of long side 12a Line segment connecting mid points of long side 20 Short side 30 Both ends of long side (vertex of approximately square)
40 Diagonal line 42 Intersection of diagonal lines 50 Center part 52 Line segment that is 1/4 of the dimension in the long side direction from the short side 60 Long axis 100 All solid state battery of the present invention 200 Conventional all solid state battery

Claims (1)

An all solid state battery having at least one unit all solid state battery,
The unit all solid state battery includes a positive electrode current collector layer, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector layer in this order.
The all-solid-state battery has a substantially rectangular outer peripheral shape composed of two long sides facing each other and two short sides facing each other in the surface direction, and the two long sides Each of the sides exists so as to cross a region closer to the intersection of the substantially rectangular diagonal lines than a line segment connecting both ends of each of the long sides, thereby, in the central portion of the all solid state battery. The length in the short side direction is shorter than any of the two short sides,
All solid battery.

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