Battery pack

Abstract

To provide a battery pack capable of discharging gas even when a small amount of gas is generated.SOLUTION: A battery pack 1 mounted on an automobile includes a battery case that houses an all-solid-state battery containing a sulfur-based material in a positive electrode layer and / or an electrolyte layer, the battery case has a ventilation port 115 provided at a corner portion 14 of the battery case and discharging the gas inside the battery case to the outside. Even the small amount of gas that builds up gradually during normal use of the vehicle can be exhausted.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a battery pack to be mounted on a mobile object. [Background technology]

[0002] A gas exhaust device is known that has a battery pack mounted inside the vehicle cabin, an exhaust path connecting the battery pack to the outside of the vehicle, an exhaust lid provided at a gas exhaust port of the exhaust path, and a control unit that operates the exhaust lid depending on the state of the battery pack (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-39006 Summary of the Invention [Problem to be solved by the invention]

[0004] This gas exhaust device opens the exhaust lid when a gas concentration detector detects the generation of a certain amount of gas or more, so it has the problem of not being able to deal with the small amount of gas that gradually accumulates during normal use of the vehicle.

[0005] The problem to be solved by the present invention is to provide a battery pack that is capable of discharging gas even when a small amount of gas is generated. [Means for solving the problem]

[0006] The present invention solves the above problem by providing a battery case with ventilation holes at the corners for discharging gas inside the battery case to the outside. [Effects of the Invention]

[0007] According to the present invention, the battery case has ventilation holes in the corners that allow gas inside the battery case to be discharged to the outside, so that even small amounts of gas that gradually accumulate during normal use of the vehicle can be discharged. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a battery pack according to an embodiment of the present invention attached to the underside of the floor of an automobile body. [Figure 2] FIG. 2 is a plan view showing a battery pack according to an embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4(a) is a plan view of an all-solid-state battery constituting a battery according to an embodiment of the present invention, and FIG. 4(b) is a cross-sectional view taken along line IV-IV in FIG. 4(a). [Figure 5] FIG. 5 is a flowchart illustrating the procedure of the control process executed by the control unit in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a battery pack according to this embodiment attached to the underside of the floor of a vehicle body. Fig. 2 is a plan view showing the battery pack according to this embodiment. Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. In the drawings, Fr indicates the front direction of the vehicle 2, UPR indicates the upper direction of the vehicle 2, RH indicates the right direction of the vehicle 2, and LH indicates the left direction of the vehicle 2.

[0010] The battery pack of this embodiment is mounted on a mobile body such as an automobile. As shown in Fig. 1, the battery pack 1 of this embodiment is attached to almost the entire surface of the underside 21 of the body 20 of an automobile 2, from the front of the front floor panel 23 to the rear floor panel 24. Note that the reference numerals 22 and 25 indicate dash panels and sills, respectively.

[0011] 2 and 3, the battery pack 1 of this embodiment includes a battery case 10 that houses multiple batteries 3. The battery 3 (also called a battery pack) in this embodiment includes multiple battery modules, each housed in a module case. Multiple thin batteries (also called cells) are housed in a stacked state inside the module case.

[0012] The cell of this embodiment is an all-solid-state battery (all-solid-state lithium-ion secondary battery). That is, the all-solid-state battery includes a power generating element having a positive electrode including a positive electrode active material layer containing a positive electrode active material capable of absorbing and releasing lithium ions, a negative electrode including a negative electrode active material layer containing a negative electrode active material capable of absorbing and releasing lithium ions, and a solid electrolyte layer interposed between the positive electrode active material layer and the negative electrode active material layer. In addition to the power generating element, the all-solid-state battery also includes an electrode tab and an exterior member that houses the electrode tab and the power generating element. Furthermore, the all-solid-state battery is a battery that uses at least a sulfur-based material, and the positive electrode material and / or the solid electrolyte material contain a sulfur component.

[0013] Here, the structure of the all-solid-state battery 30 constituting the battery 3 will be described with reference to Figures 4(a) and 4(b). Figure 4(a) is a plan view of the all-solid-state battery 30 according to this embodiment, and Figure 4(b) is a cross-sectional view taken along line IV-IV in Figure 4(a). Note that the structure of the all-solid-state battery 30 is not limited to the structure shown in Figures 4(a) and 4(b), and other structures may also be used.

[0014] The all-solid-state battery 30 is composed of a power generating element 301 having three positive electrode layers 302, seven electrolyte layers 303, and three negative electrode layers 304, positive electrode tabs 305 connected to the three positive electrode layers 302, respectively, negative electrode tabs 306 connected to the three negative electrode layers 304, and an upper exterior member 307 and a lower exterior member 308 that house and seal the power generating element 301, positive electrode tabs 305, and negative electrode tabs 306.

[0015] The numbers of the positive electrode layers 302, the electrolyte layers 303, and the negative electrode layers 304 are not particularly limited, and the power generating element 301 may be configured with one positive electrode layer 302, three electrolyte layers 303, and one negative electrode layer 304, or the numbers of the positive electrode layers 302, the electrolyte layers 303, and the negative electrode layers 304 may be appropriately selected as needed.

[0016] The positive electrode layer 302 constituting the power generating element 301 includes a positive electrode current collector 302a extending to the positive electrode tab 305, and positive electrode active material layers formed on both main surfaces of a portion of the positive electrode current collector 302a. The positive electrode current collector 302a constituting the positive electrode layer 302 can be made of an electrochemically stable metal foil such as aluminum foil, aluminum alloy foil, copper-titanium foil, or stainless steel foil. Metals such as nickel, iron, and copper may be used for the positive electrode current collector 302a. Other materials that may be used include a clad material of nickel and aluminum, a clad material of copper and aluminum, and the like.

[0017] Instead of metal, a conductive resin may be used for the positive electrode current collector 302a. The conductive resin may be a resin obtained by adding a conductive filler to a non-conductive polymeric material as needed. Examples of non-conductive polymeric materials include polyethylene (PE; high-density polyethylene (HDPE), low-density polyethylene (LDPE), etc.), polypropylene (PP), and polyethylene terephthalate (PET), which have excellent potential resistance. The conductive filler can be any conductive material. Examples of materials with excellent conductivity, potential resistance, or lithium ion blocking properties include metals and conductive carbon. Examples of metals include, but are not limited to, at least one metal selected from the group consisting of Ni, Ti, Al, Cu, Pt, Fe, Cr, Sn, Zn, In, and Sb, or alloys or metal oxides containing such metals.

[0018] The positive electrode active material layer constituting the positive electrode layer 302 is not particularly limited, but may be a layered rock salt active material such as LiCoO2, LiMnO2, LiNiO2, LiVO2, or Li(Ni-Mn-Co)O2; LiMn2O4, LiNi 0.5 Mn 1.5 Examples of oxide active materials include spinel-type active materials such as LiFePO4 and LiMnPO4, olivine-type active materials such as LiFeSiO4 and LiMnSiO4, and Si-containing active materials such as LiFeSiO4 and LiMnSiO4. 12 Examples of such composite oxides include those containing lithium and nickel. Composite oxides containing lithium and nickel are preferably used, and more preferably Li(Ni-Mn-Co)O2 and those in which part of the transition metals in these oxides are substituted with other elements (hereinafter simply referred to as "NMC composite oxides"). As mentioned above, NMC composite oxides also include composite oxides in which part of the transition metal elements are substituted with other metal elements. In such cases, examples of such other elements include Ti, Zr, Nb, W, and P.

[0019] The cathode active material layer may contain a sulfur-based cathode active material. Examples of sulfur-based cathode active materials include particles or thin films of organic sulfur compounds or inorganic sulfur compounds, and any material can be used as long as it utilizes the oxidation-reduction reaction of sulfur to release lithium ions during charging and absorb lithium ions during discharging. Examples of organic sulfur compounds include disulfide compounds and sulfur-modified polyacrylonitrile. Examples of inorganic sulfur compounds include sulfur (S), S-carbon composite, TiS2, TiS3, TiS4, NiS, NiS2, CuS, FeS2, Li2S, MoS2, and MoS3.

[0020] Note that positive electrode active materials other than those described above may also be used. The shape of the positive electrode active material may be, for example, particulate (spherical, fibrous), thin film, etc. The amount of positive electrode active material contained in the positive electrode active material layer is not particularly limited. The positive electrode active material layer may further contain at least one of a solid electrolyte, a conductive additive, and a binder, as needed. The shape of the positive electrode active material may be, for example, particulate (spherical, fibrous), thin film, etc. The amount of positive electrode active material contained in the positive electrode active material layer is not particularly limited. The positive electrode active material layer may further contain at least one of a solid electrolyte, a conductive additive, and a binder, as needed. Examples of solid electrolytes include sulfide solid electrolytes and oxide solid electrolytes, and those exemplified as solid electrolytes that can form the electrolyte layer 303 described below can be used.

[0021] The conductive additive is not particularly limited, but is preferably particulate or fibrous in shape. When the conductive additive is particulate, the shape of the particles is not particularly limited, and may be any shape such as powder, sphere, rod, needle, plate, column, irregular shape, scale, or spindle shape. When the conductive additive is particulate, the average particle diameter (primary particle diameter) is not particularly limited, but is preferably 0.01 to 10 μm from the viewpoint of the electrical characteristics of the battery.

[0022] Examples of binders include thermoplastic polymers such as polybutylene terephthalate, polyethylene terephthalate, polyvinylidene fluoride (PVDF) (including compounds in which hydrogen atoms are substituted with other halogen elements), polyethylene, polypropylene, polymethylpentene, polybutene, polyethernitrile, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, ethylene-vinyl acetate copolymer, polyvinyl chloride, styrene-butadiene rubber (SBR), ethylene-propylene-diene copolymer, styrene-butadiene-styrene block copolymer and its hydrogenated products, styrene-isoprene-styrene block copolymer and its hydrogenated products; tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene-tetrafluoroethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTF), etc. Fluororesins such as vinylidene fluoride-hexafluoropropylene fluororubber (VDF-HFP fluororubber), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene fluororubber (VDF-HFP-TFE fluororubber), vinylidene fluoride-pentafluoropropylene fluororubber (VDF-PFP fluororubber), vinylidene fluoride-pentafluoropropylene-tetrafluoroethylene fluororubber (VDF-PFP-TFE fluororubber), vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoroethylene fluororubber (VDF-PFMVE-TFE fluororubber), vinylidene fluoride-chlorotrifluoroethylene fluororubber (VDF-CTFE fluororubber), and other vinylidene fluoride fluororubber; epoxy resins; and the like. Among these, polyimide, styrene-butadiene rubber, carboxymethyl cellulose, polypropylene, polytetrafluoroethylene, polyacrylonitrile, and polyamide are more preferable.

[0023] Each of the positive electrode current collectors 302a constituting the three positive electrode layers 302 is joined to a positive electrode tab 305. The positive electrode tab 305 may be made of aluminum foil, aluminum alloy foil, copper foil, nickel foil, or the like.

[0024] The negative electrode layer 304 constituting the power generating element 301 has a negative electrode side current collector 304a extending to the negative electrode tab 306, and a negative electrode active material layer formed on each of the two main surfaces of a portion of the negative electrode side current collector 304a. The negative electrode side current collector 304a of the negative electrode layer 304 is an electrochemically stable metal foil such as nickel foil, copper foil, stainless steel foil, or iron foil.

[0025] The negative electrode layer 304 is formed of a layer containing a negative electrode active material. The type of negative electrode active material is not particularly limited, but examples thereof include carbon materials, metal oxides, and metal active materials. Examples of carbon materials include natural graphite, artificial graphite, mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon. Examples of metal oxides include Nb2O5, Li4Ti5O 12 , SiO, etc. Furthermore, examples of the metal active material include simple metals such as In, Al, Si, and Sn, and alloys such as TiSi and La3Ni2Sn7.

[0026] The negative electrode active material may be a metal containing Li. Such a negative electrode active material is not particularly limited as long as it is an active material containing Li. It may be Li metal or a lithium alloy containing Li. Examples of lithium alloys include alloys of lithium and at least one metal selected from gold (Au), magnesium (Mg), aluminum (Al), calcium (Ca), zinc (Zn), tin (Sn), and bismuth (Bi). The lithium alloy may also be an alloy of lithium and two or more of the above-mentioned metals. Specific examples of lithium alloys include lithium-gold alloy (Li-Au), lithium-magnesium alloy (Li-Mg), lithium-aluminum alloy (Li-Al), lithium-calcium alloy (Li-Ca), lithium-zinc alloy (Li-Zn), lithium-tin alloy (Li-Sn), and lithium-bismuth alloy (Li-Bi).

[0027] The negative electrode active material layer may contain a lithium alloy, and its configuration is not particularly limited. For example, when the metal other than lithium constituting the lithium alloy is "Me," the negative electrode active material layer may be any of the following embodiments (1) to (3): (1) A single layer consisting of only a lithium alloy (i.e., a Li-Me layer); (2) A layer comprising a layer of lithium metal and a layer of a lithium alloy (i.e., a Li layer / Li-Me layer); or (3) A layer comprising a layer of lithium metal, a layer of a lithium alloy, and a layer of a metal other than lithium (i.e., a Li layer / Li-Me layer / Me layer). In the embodiment (2), the layer of the lithium alloy (Li-Me layer) is preferably the layer on the electrolyte layer 103 side (the layer that forms the interface with the electrolyte layer 103). In the embodiment (3), the layer of the metal other than lithium (Me layer) is preferably the layer on the electrolyte layer 103 side (the layer that forms the interface with the electrolyte layer 103). When a lithium metal layer containing lithium metal and a layer (intermediate layer) containing a metal other than lithium metal are used, the intermediate layer is a layer between the lithium metal layer and the solid electrolyte, and it is desirable that at least a portion of the lithium metal and at least a portion of the metal forming the intermediate layer are alloyed.

[0028] For example, when the negative electrode has the above-mentioned configuration (3), i.e., a configuration including a layer of lithium metal, a layer of a lithium alloy, and a layer of a metal other than lithium (i.e., Li layer / Li-Me layer / Me layer), stacking the lithium metal and the metal other than lithium alloys the interface between them, thereby forming a layer of lithium alloy at the interface. The method for stacking the lithium metal and the metal other than lithium is not particularly limited, but examples include a method in which the metal other than lithium is deposited on the layer of lithium metal by vacuum deposition or the like, thereby forming a layer of the metal other than lithium on the layer of lithium metal and alloying the interface between them. Alternatively, examples include a method in which lithium metal is deposited on the layer of the metal other than lithium by vacuum deposition or the like, and forming a layer of lithium metal on the layer of the metal other than lithium and alloying the interface between them.

[0029] In the all-solid-state battery 30 of this embodiment, the three negative electrode layers 304 are configured such that each negative electrode-side current collector 304a constituting the negative electrode layer 304 is joined to a single negative electrode tab 306. That is, in the all-solid-state battery 30 of this embodiment, the negative electrode layers 304 are joined to a single common negative electrode tab 306.

[0030] The electrolyte layer 303 of the power generating element 301 prevents a short circuit between the above-described positive electrode layer 302 and negative electrode layer 304, contains a solid electrolyte as a main component, and is a layer interposed between the above-described positive electrode active material layer and negative electrode active material layer. Examples of the solid electrolyte include sulfide solid electrolytes, oxide solid electrolytes, and polymer solid electrolytes, but a sulfide solid electrolyte is preferred.

[0031] Examples of the sulfide solid electrolyte include, for example, LiI-Li2S-SiS2, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, LiI-Li3PS4, LiI-LiBr-Li3PS4, Li3PS4, Li6PS5Cl, Li2S-P2S5, Li2S-P2S5-LiI, Li2S-P2S5-Li2O, Li2S-P2S5-Li2OLiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-ZmSn (where m and n are positive numbers and Z is any of Ge, Zn, Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-LixMOy (where x and y are positive numbers and M is any of P, Si, Ge, B, Al, Ga, In), etc. The description of "Li2S-P2S5" means a sulfide solid electrolyte formed using a raw material composition containing Li2S and P2S5, and the same applies to other descriptions.

[0032] The sulfide solid electrolyte may, for example, have a Li3PS4 skeleton, a Li4P2S7 skeleton, or a Li4P2S6 skeleton. Examples of the sulfide solid electrolyte having a Li3PS4 skeleton include, for example, LiI-Li3PS4, LiI-LiBr-Li3PS4, and Li3PS4. Further, examples of the sulfide solid electrolyte having a Li4P2S7 skeleton include, for example, a Li-P-S-based solid electrolyte called LPS (e.g., Li7P3S 11 ). Additionally, as the sulfide solid electrolyte, for example, LGPS represented by Li (4-x) Ge (1-x) P x S4 (where 0 < x < 1) may be used. Among them, the sulfide solid electrolyte is preferably a sulfide solid electrolyte containing the P element, and more preferably a material mainly composed of Li2S-P2S5. Further, the sulfide solid electrolyte may contain a halogen (F, Cl, Br, I).

[0033] Furthermore, when the sulfide solid electrolyte is a Li2S-P2S5 system, the molar ratio of Li2S and P2S5 is preferably within the range of Li2S:P2S5=50:50 to 100:0, and particularly preferably Li2S:P2S5=70:30 to 80:20. Furthermore, the sulfide solid electrolyte may be sulfide glass, crystallized sulfide glass, or a crystalline material obtained by a solid-phase method. Note that sulfide glass can be obtained, for example, by mechanical milling (such as a ball mill) of a raw material composition. Furthermore, crystallized sulfide glass can be obtained, for example, by heat treating sulfide glass at a temperature equal to or higher than the crystallization temperature. Furthermore, the ionic conductivity (e.g., Li ion conductivity) of the sulfide solid electrolyte at room temperature (25°C) is, for example, 1 × 10 -5 S / cm or more is preferable, and 1×10 -4 It is more preferable that the ionic conductivity is S / cm or more. The ionic conductivity value of the solid electrolyte can be measured by an AC impedance method.

[0034] Examples of oxide solid electrolytes include compounds having a NASICON structure. An example of a compound having a NASICON structure is a compound represented by the general formula Li 1+x Al x Ge 2-x Compounds (LAGP) represented by (PO4)3 (0≦x≦2), general formula Li 1+x Al x Ti 2-x (PO4)3 (0≦x≦2) (LATP) and the like. Another example of an oxide solid electrolyte is LiLaTiO (for example, Li 0.34 La 0.5 1TiO3), LiPON (e.g., Li 2.9 PO 3.3 N 0.46 ), LiLaZrO (e.g., Li7La3Zr2O 12 ) and the like. The electrolyte layer 303 may further contain a binder in addition to the above-mentioned solid electrolyte. The binder is not particularly limited, but the binders mentioned above can be used, for example.

[0035] The content of the solid electrolyte is, for example, preferably in the range of 10 to 100 mass %, more preferably in the range of 50 to 100 mass %, and further preferably in the range of 90 to 100 mass %.

[0036] As described above, the cathode layer 302 used in this embodiment contains a sulfur compound as a cathode active material, and thus uses a sulfur-based material, while the electrolyte layer 303 contains a sulfide solid electrolyte as a main component, and thus uses a sulfur material. Note that the sulfur-based material may be used in either the cathode layer 302 or the electrolyte layer 303.

[0037] As shown in FIG. 4(b), the positive electrode layers 302 and the negative electrode layers 304 are alternately stacked with the electrolyte layers 303 interposed therebetween, and the electrolyte layers 303 are stacked on the top and bottom layers, respectively, thereby forming the power generating element 301.

[0038] Power generating element 301 configured as described above is housed in and sealed within upper exterior member 307 and lower exterior member 308. Upper exterior member 307 and lower exterior member 308 for sealing power generating element 301 are formed from a flexible material, such as a resin film of polyethylene, polypropylene, or the like, or a resin-metal thin film laminate material in which both sides of a metal foil such as aluminum are laminated with a resin such as polyethylene or polypropylene, and by heat-sealing upper exterior member 307 and lower exterior member 308 together, power generating element 301 is sealed in a state in which positive electrode tab 305 and negative electrode tab 306 are exposed to the outside.

[0039] Note that, in the portions of positive electrode tab 305 and negative electrode tab 306 that come into contact with upper exterior member 307 and lower exterior member 308, sealing films 309 are provided to ensure adhesion with upper exterior member 307 and lower exterior member 308. The sealing film 309 is not particularly limited, but can be made of, for example, a synthetic resin material that has excellent electrolyte resistance and heat-sealing properties, such as polyethylene, modified polyethylene, polypropylene, modified polypropylene, or ionomer.

[0040] As described above, the all-solid-state battery 30 constituting the battery 3 of this embodiment contains a sulfur-based material. If sulfur reacts with water for some reason, hydrogen sulfide is generated. If the hydrogen sulfide leaks out of the battery 3, it may corrode the components inside the battery case 10. Therefore, even if a small amount of hydrogen sulfide is generated, it is necessary to discharge the generated hydrogen sulfide to the outside of the battery case 10. In contrast, in this embodiment, the ventilation opening 115 is provided in the corner 14 of the battery case 10, so that the hydrogen sulfide is discharged to the outside.

[0041] 2 and 3, the battery case 10 includes a bottom frame 11, a plurality of (four in this example) plate-shaped side frames 12a to 12d fixed to the outer periphery of the bottom frame 11, and a cover member 13 that covers the side frames 12a to 12d. The bottom frame 11, the side frames 12a to 12d, and the cover member 13 can be made of, but are not limited to, extruded aluminum.

[0042] As shown in Fig. 2, bottom frame 11 is a plate-like member having a rectangular planar shape. As shown in Fig. 3, bottom frame 11 has a first main surface 11a and a second main surface 11b on the opposite side thereof. When bottom frame 11 is attached to automobile body 20, first main surface 11a corresponds to the upper surface and second main surface 11b corresponds to the lower surface. Bottom frame 11 has a mounting portion 111 on which battery 3 is mounted and a step portion 112 provided at a position lower than mounting portion 111.

[0043] 2 and 3, the step portion 112 has a rectangular frame-like planar shape, is provided on the outer periphery of the bottom frame 11, and is positioned further outward than the mounting portion 111. The first main surface 11a of this step portion 112 is recessed in a direction away from the cover member 13 more than the first main surface 11a of the mounting portion 111, so that the height of the step portion 112 is lower than the height of the mounting portion 111.

[0044] The step portion 112 has a plurality of (four in this example) flat portions 113 located at the corners 14 of the battery case 10, and a plurality of (four in this example) inclined portions 114 located between the flat portions 113. The flat portions 113 are located at the four corners of the step portion 112, and have flat first main surfaces 11a. On the other hand, the inclined portions 114 are located on the four sides of the step portion 112, and have inclined first main surfaces 11a. The inclined portions 114 have, on the first main surface 11a, an apex 114a and inclined surfaces 114b and 114c that are inclined so that the height continuously decreases from the apex 114a to the flat portions 113.

[0045] The formation of such inclined surfaces 114b and 114c in the step portion 112 makes it easier for gases such as hydrogen sulfide generated from the battery 3 to be guided to the flat portion 113 having the ventilation opening 115. This improves exhaust efficiency.

[0046] In this embodiment, a ventilation opening 115 is provided in the flat portion 113 of the stepped portion 112 to discharge gases such as hydrogen sulfide generated inside the battery case 10 to the outside of the battery case 10. As shown in FIG. 3 , this ventilation opening 115 is a cylindrical through-hole that penetrates the bottom frame 11 along the thickness direction of the bottom frame 11, and is located at a corner 14 of the battery case 10. Note that the shape of this through-hole is not limited to a cylindrical shape and may be any shape, such as a polygonal shape or a slit shape. Furthermore, this ventilation opening 115 may be connected to a pipe or the like that discharges gas to the outside of the automobile 2.

[0047] Thus, hydrogen sulfide, which has a higher specific gravity than air, tends to accumulate in the lower part of the battery case 10. For this reason, hydrogen sulfide tends to accumulate more easily in the stepped part 112, which is located lower than the mounting part 111 on which the battery 3 is mounted, and therefore, by providing a ventilation opening 115 in this stepped part 112, hydrogen sulfide can be efficiently guided to the ventilation opening 115. This improves the efficiency of exhausting hydrogen sulfide.

[0048] In this embodiment, ventilation holes 115 are provided in the bottom surface (bottom frame 11) of the battery case 10 at the corners 14. As described above, hydrogen sulfide has a higher specific gravity than air and tends to accumulate at the bottom of the battery case 10, so providing the ventilation holes 115 in the bottom surface can improve exhaust efficiency.

[0049] In this embodiment, the ventilation openings 115 are provided on the bottom surfaces of the corners 14, but this is not limiting. For example, the ventilation openings 115 may be provided on the side surfaces (side frames 12a to 12b) of the corners 14. However, from the viewpoint of exhaust efficiency, it is preferable to provide the ventilation openings 115 in the lower parts of the corners 14, as in this embodiment. Here, the lower part of the battery case 10 refers to a portion located in an area that is half or less (H / 2 or less) of the height H of the side frames 12a to 12b, and is the portion that includes the lower halves of the side frames 12a to 12d and the bottom frame 11 in this embodiment.

[0050] A vent member 116 is fitted into the opening on the first main surface 11a side of the ventilation hole 115. This vent member 116 is a member that allows gas to pass through but does not allow moisture to pass through, and can prevent moisture from entering the battery case 10 while maintaining the exhaust performance of the ventilation hole 115.

[0051] This vent member 116 has a bottom member 116a, a breathable waterproof sheet 116b, and a cap member 116c. The bottom member 116a is a cylindrical resin member having an outer diameter that is the same as the inner diameter of the ventilation opening 115, and is inserted into and fitted with the ventilation opening 115. The shape of the bottom member 116a is not particularly limited, and may be changed appropriately depending on the shape of the ventilation opening 115.

[0052] A breathable waterproof sheet 116b is placed at one end (the upper end in this example) of the opening of the bottom member 116a so as to close the opening. This breathable waterproof sheet 116b is a sheet made of a material that allows gas to pass through but does not allow water to pass through. It is not particularly limited, but for example, a sheet made of a PTFE (polytetrafluoroethylene) porous film with a backing material layer formed thereon can be used. In this case, the breathable waterproof sheet is adhered to the bottom member 116a via the backing material.

[0053] The cap member 116c is a disk-shaped resin member having approximately the same diameter as the bottom member 116a, and is formed integrally with the bottom member 116a. The cap member 116c is disposed above the breathable waterproof sheet 116b at a distance from the breathable waterproof sheet 116b, and protects the breathable waterproof sheet 116b by covering it from above.

[0054] Inside the ventilation opening 115, a sliding shutter 117 housed in a shutter housing portion 117a is arranged below the vent member 116. The sliding shutter 117 is a member having a flat shape that can close the ventilation opening 115, and opens and closes the ventilation opening 115 by moving horizontally using an actuator or the like (not shown).

[0055] In this embodiment, the vent member 116 is arranged above the ventilation opening 115 and the sliding shutter 117 is arranged below the ventilation opening 115, but this is not limitative and the vent member 116 and the sliding shutter 117 may be arranged upside down. In other words, the vent member 116 may be arranged on the second main surface 11b side of the bottom frame 11, and the sliding shutter 117 may be arranged on the first main surface 11a side of the bottom frame 11.

[0056] The actuator that drives this sliding shutter 117 is connected to the control unit 15 via a communication line 16 (see FIG. 2). This control unit 15 has a CPU, a memory, etc. The control unit 15 opens and closes the ventilation opening 115 depending on the traveling state of the moving body (automobile 2) in accordance with the procedure shown in FIG.

[0057] 5 is a flowchart illustrating the procedure of the control process executed by the control unit 15 in this embodiment. First, in step S1, the control unit 15 acquires vehicle speed information from a speed sensor. The control unit 15 may acquire the vehicle speed information from a speed sensor provided in the automobile 2. Alternatively, the control unit 15 may be provided with a vehicle speed sensor and acquire the vehicle speed information from the vehicle speed sensor.

[0058] Next, in step S2, the control unit 15 determines whether the vehicle speed is 0. That is, the control unit 15 determines whether the automobile 2 is stopped. If the control unit 15 determines that the vehicle speed is not 0, it executes the control process of step S3, and if the control unit 15 determines that the vehicle speed is 0, it executes the control process of step S4.

[0059] In step S3, the control unit 15 horizontally moves the sliding shutter 117 by controlling the actuator via the communication line 16. As a result, the control unit 15 opens the ventilation opening 115. Note that if the ventilation opening 115 was open before executing step S3, the control unit 15 maintains the position of the sliding shutter 117, thereby maintaining the ventilation opening 115 in the open state.

[0060] In step S4, the control unit 15 horizontally moves the sliding shutter 117 by controlling the actuator via the communication line 16. As a result, the control unit 15 closes the ventilation opening 115. Note that if the ventilation opening 115 was closed before executing step S4, the control unit 15 maintains the position of the sliding shutter 117, thereby maintaining the ventilation opening 115 in the closed state.

[0061] As described above, the control unit 15 closes the ventilation opening 115 when the automobile 2 is stopped, and opens the ventilation opening 115 when the automobile 2 is moving. In this way, by preventing hydrogen sulfide from being emitted while the automobile 2 is stopped, it is possible to prevent hydrogen sulfide from accumulating around the stopped vehicle.

[0062] Furthermore, because hydrogen sulfide has a greater specific gravity than air, the inertial force acting on hydrogen sulfide when the vehicle 2 is turning is relatively greater than the inertial force acting on air. Therefore, when the vehicle 2 turns, hydrogen sulfide moves more easily than air, and therefore hydrogen sulfide tends to accumulate at the corners 14 of the battery case 10. Specifically, for example, when the vehicle 2 turns in a forward right direction, hydrogen sulfide moves in a rearward left direction along the side frames 12a, 12b, and moves toward the rear left corner 14 inside the battery case 10. Similarly, when the vehicle 2 turns in a direction other than the forward right direction, hydrogen sulfide moves to the front right, front left, and rear right corners 14.

[0063] As such, hydrogen sulfide tends to accumulate in the corners of the battery case, so even if ventilation holes are provided on the sides of the bottom frame, hydrogen sulfide is unlikely to accumulate near the ventilation holes, and hydrogen sulfide cannot be sufficiently discharged. In contrast, in the battery pack 1 of this embodiment, ventilation holes 115 are located at the corners 14 of the battery case 10, and hydrogen sulfide tends to accumulate near the ventilation holes 115, so hydrogen sulfide can be efficiently discharged. Therefore, even small amounts of hydrogen sulfide generated during normal use of the automobile 2 can be discharged.

[0064] Furthermore, in this embodiment, unlike the case where gases are discharged through multiple pipes by changing the discharge route depending on the specific gravity of the gas, gases with high specific gravity such as hydrogen sulfide can be discharged outside the automobile 2 through a single discharge passage, thereby reducing costs.

[0065] In addition, in this embodiment, hydrogen sulfide that moves to the vicinity of the ventilation opening 115 due to the movement of the automobile 2, such as turning, is discharged. Therefore, there is no need to provide a fan or the like to forcibly move the hydrogen sulfide, and the manufacturing cost of the battery pack 1 can be reduced.

[0066] Although the embodiments of the present invention have been described above, these embodiments are described to facilitate understanding of the present invention and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0067] For example, although the battery case 10 in the above embodiment has a rectangular planar shape, this is not limited thereto and the battery case 10 may have a polygonal planar shape other than a square. In this case, too, the vicinity of the corners of the polygon becomes the corners, and ventilation holes can be provided in the corners. Furthermore, although ventilation holes are provided in all corners in the above embodiment, this is not limited thereto and ventilation holes may be provided only in some of the multiple corners.

[0068] In addition, in the above embodiment, an example was described in which both the vent member 116 and the sliding shutter 117 were provided in the ventilation opening 115, but this is not limited to this, and only one of the vent member 116 and the sliding shutter 117 may be provided, or both the vent member 116 and the sliding shutter 117 may be omitted.

[0069] In the above embodiment, the ventilation opening 115 is opened and closed by operating the slide shutter 117, but the invention is not limited to this, and the ventilation opening 115 may be opened and closed by other means. [Explanation of symbols]

[0070] 1. Battery pack 10...Battery case 11...Bottom frame 11a...first principal surface 11b...second principal surface 111...Placement section 112...Step 113...Flat area 114…Slope part 114a...top 114b,114c…Slope surface 115...Ventilation vent 116...Vent member 116a...Bottom member 116b...Breathable waterproof sheet 116c...Cap member 117...Slide shutter 117a...shutter housing section 12a~12d...Side frame 13...Cover member 14...Corner 15...Control unit 16...Communication line 2. Automobiles 20...Car body 21...Underside of floor 22...Dash panel 23...Front floor panel 24...Rear floor panel 25...sil 3. Battery 30…All-solid-state battery

Claims

1. A battery pack mounted on a rotatable mobile body, a battery case that houses an all-solid-state battery containing a sulfur-based material in a positive electrode and / or a solid electrolyte; the battery case has a ventilation opening provided at a corner of the battery case for discharging gas inside the battery case to the outside, the ventilation opening is provided in the corner portion at a lower portion of the battery case, the lower portion is a portion located in an area equal to or less than half the height of the battery case, the battery case has a bottom frame on which the all-solid-state battery is placed, The bottom frame is a mounting portion on which the all-solid-state battery is mounted; a step portion provided on the outer periphery of the bottom frame and lower in height than the placement portion;

2. 2. The battery pack according to claim 1, The ventilation opening is provided on the bottom surface of the battery case at the corner.

3. 2. The battery pack according to claim 1, The step portion has an inclined surface that is inclined so that the height decreases toward the corner portion of the battery pack.

4. The battery pack according to any one of claims 1 to 3, a control unit that operates to open or close the ventilation opening depending on the operating state of the moving body; The control unit closes the ventilation opening when the moving object is stationary, and opens the ventilation opening when the moving object is moving.

5. The battery pack according to any one of claims 1 to 4, The battery pack has a vent member provided at the ventilation opening, the vent member including a breathable and waterproof sheet.

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