WO2020184359A1

WO2020184359A1 - Battery

Info

Publication number: WO2020184359A1
Application number: PCT/JP2020/009334
Authority: WO
Inventors: 良太 ▲柳▼澤; 剛正山本
Original assignee: 株式会社エンビジョンＡｅｓｃエナジーデバイス
Priority date: 2019-03-08
Filing date: 2020-03-05
Publication date: 2020-09-17
Also published as: JP2020145128A; JP7348733B2; JP2023165682A

Abstract

A battery (10) includes a positive electrode (100) and a first insulation layer (322). The positive electrode (100) includes a current collector (110) and a first active material layer (122). The current collector (110) has a first surface (112) and a second surface (114). The second surface (114) is on the reverse side from the first surface (112). The first active material layer (122) is positioned on the first surface (112) of the current collector (110). The first insulation layer (322) faces the first active material layer (122) of the positive electrode (100). The first active material layer (122) includes active material particles represented by Li_aNi_bM_1-bO₂ (where, 0.95≤a≤1.05, b≥0.50, and M is at least one element selected from among Co, Mn, Al, Ti, Zr, Na, Ba, and Mg). The first insulation layer (322) includes magnesium hydroxide particles. The product of the basis weight and specific surface area of the magnesium hydroxide particles is 0.7 or more times greater than the product of the basis weight and specific surface area of the active material particles.

Description

battery

The present invention relates to a battery.

As a type of battery, a secondary battery, especially a non-aqueous electrolyte secondary battery, has been developed. The non-aqueous electrolyte secondary battery includes a positive electrode, a negative electrode and a separator. The separator is located between the positive electrode and the negative electrode.

Patent Document 1 describes an example of a separator. The separator includes a polyethylene microporous membrane and a heat resistant porous layer on both sides of the polyethylene microporous membrane. The heat-resistant porous layer contains an inorganic filler composed of polymethaphenylene isophthalamide and aluminum hydroxide.

Patent Document 2 describes an example of a separator. The separator includes a polyethylene microporous membrane and a porous layer on both sides of the polyethylene microporous membrane. The porous layer contains an inorganic filler composed of meta-type total aromatic polyamide and α-alumina.

Patent Documents 3 and 4 describe an example of a separator. The separator includes a polyethylene porous film and a heat resistant porous layer on the polyethylene porous film. The heat-resistant porous layer contains liquid crystal polyester and alumina particles.

Patent Document 5 describes improving the resistance of a battery crush test. Patent Document 5 specifies the tensile elongation of the positive electrode, the tensile elongation of the negative electrode, and the tensile elongation of the separator in order to improve the resistance to the crushing test.

Japanese Unexamined Patent Publication No. 2009-231281 Japanese Unexamined Patent Publication No. 2010-160939 Japanese Unexamined Patent Publication No. 2008-31221 Japanese Unexamined Patent Publication No. 2008-307893 JP-A-2010-165664

In non-aqueous electrolyte secondary batteries, especially lithium ion batteries, gas (for example, carbon dioxide gas generated by oxidative decomposition of carbonic acid ester in the electrolytic solution) may be generated during charging and discharging. The residual gas in the cell may cause various troubles (for example, an increase in the distance between the adjacent positive electrode and the negative electrode or an increase in the internal pressure of the cell).

An example of an object of the present invention is to reduce residual gas in a cell. Other objects of the invention will become apparent from the disclosure herein.

According to one aspect of the invention
A positive electrode including a current collector having a first surface and a second surface opposite to the first surface, and a first active material layer located on the first surface of the current collector.
The first insulating layer of the positive electrode facing the first active material layer and
Including
The first active material layer is Li _a Ni _b M _1-b O ₂ (0.95 ≦ a ≦ 1.05, b ≧ 0.50, M is Co, Mn, Al, Ti, Zr, Na, It contains active material particles represented by (one or more elements selected from Ba and Mg).
The first insulating layer contains magnesium hydroxide particles and contains magnesium hydroxide particles.
A battery is provided in which the product of the grain size and the specific surface area of the magnesium hydroxide particles is 0.7 times or more the product of the grain size and the specific surface area of the active material particles.

According to the above-described aspect of the present invention, the residual gas in the cell can be reduced.

It is a top view of the battery which concerns on embodiment. It is sectional drawing of AA'of FIG. It is an enlarged view of a part of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same constituents will be referred to with the same numerals, and the description thereof will not be repeated.

FIG. 1 is a top view of the battery 10 according to the embodiment. FIG. 2 is a cross-sectional view taken along the line AA'of FIG. FIG. 3 is an enlarged view of a part of FIG. FIG. 2 does not show the exterior material 400 shown in FIG. 1 for the sake of explanation.

The outline of the battery 10 will be described with reference to FIG. The battery 10 includes a positive electrode 100 and a first insulating layer 322. The positive electrode 100 includes a current collector 110 and a first active material layer 122. The current collector 110 has a first surface 112 and a second surface 114. The second surface 114 is on the opposite side of the first surface 112. The first active material layer 122 is located on the first surface 112 of the current collector 110. The first insulating layer 322 faces the first active material layer 122 of the positive electrode 100. The first active material layer 122 is Li _a Ni _b M _1-b O ₂ (0.95 ≦ a ≦ 1.05, b ≧ 0.50, M is Co, Mn, Al, Ti, Zr, Na, It contains active material particles represented by (one or more elements selected from Ba and Mg). The first insulating layer 322 contains magnesium hydroxide particles. The product of the grain size and the specific surface area of the magnesium hydroxide particles is 0.7 times or more the product of the grain size and the specific surface area of the active material particles.

According to this embodiment, the residual gas in the cell (in the space closed by the exterior material 400 described later) can be reduced. Specifically, the present inventor has newly focused on the relationship between the product of the grain and specific surface area of magnesium hydroxide particles and the product of the grain and specific surface area of active material particles in order to reduce the residual gas in the cell. As a result of the examination by the present inventor, it has been clarified that the residual gas in the cell is reduced according to the relationship between the product of magnesium hydroxide and the product of the active material particles, as will be described in detail later.

The composition ratio b of Li _a Ni _b M _1-b O ₂ may be b ≧ 0.80. Even in this case, according to the present embodiment, the residual gas in the cell can be reduced.

The details of the battery 10 will be described with reference to FIG.

The battery 10 includes a first lead 130, a second lead 230, and an exterior material 400.

The first lead 130 is electrically connected to the positive electrode 100 shown in FIG. The first lead 130 may be formed of, for example, aluminum or an aluminum alloy.

The second lead 230 is electrically connected to the negative electrode 200 shown in FIG. The second lead 230 may be formed of, for example, copper or a copper alloy or a nickel-plated product thereof.

In the example shown in FIG. 1, the exterior material 400 has a rectangular shape having four sides. In the example shown in FIG. 1, the first lead 130 and the second lead 230 protrude from a common one of the four sides of the exterior material 400. In another example, the first lead 130 and the second lead 230 may protrude from different sides (for example, sides opposite to each other) of the four sides of the exterior material 400.

The exterior material 400 contains the laminate 12 shown in FIG. 2 together with an electrolytic solution (not shown).

The exterior material 400 may include, for example, a thermosetting resin layer and a barrier layer, and may be a laminated film including, for example, a thermosetting resin layer and a barrier layer.

The resin material forming the thermosetting resin layer may be, for example, polyethylene (PE), polypropylene, nylon, polyethylene terephthalate (PET) or the like. The thickness of the thermosetting resin layer is, for example, 20 μm or more and 200 μm or less, preferably 30 μm or more and 150 μm or less, and more preferably 50 μm or more and 100 μm or less.

The barrier layer has a barrier property such as prevention of leakage of electrolytic solution or invasion of moisture from the outside, and for example, metal such as stainless steel (SUS) foil, aluminum foil, aluminum alloy foil, copper foil, and titanium foil. It may be a barrier layer formed by. The thickness of the barrier layer is, for example, 10 μm or more and 100 μm or less, preferably 20 μm or more and 80 μm or less, and more preferably 30 μm or more and 50 μm or less.

The thermosetting resin layer of the laminated film may be one layer or two or more layers. Similarly, the barrier layer of the laminated film may be one layer or two or more layers.

The electrolytic solution is, for example, a non-aqueous electrolytic solution. This non-aqueous electrolytic solution may contain a lithium salt and a solvent that dissolves the lithium salt.

Lithium salt, for _{_{_{example, LiClO 4, LiBF 4, LiPF}}} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl 4, LiCl, LiBr, LiB (C 2 H 5) ₄ , CF ₃ SO ₃ Li, CH ₃ SO ₃ Li, LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, lower fatty acid lithium carboxylate and the like may be used.

Solvents that dissolve the lithium salt are carbonate esters such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), It contains carbonates such as methyl ethyl carbonate (MEC) and vinylene carbonate (VC). Solvents include lactones such as γ-butyrolactone and γ-valerolactone; ethers such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, tetrahydrofuran and 2-methyltetraxide; sulfoxides such as dimethyl sulfoxide; 1, Oxolanes such as 3-dioxolane and 4-methyl-1,3-dioxolane; nitrogen-containing solvents such as acetonitrile, nitromethane, formamide and dimethylformamide; methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate and propionic acid. Organic acid esters such as ethyl; phosphoric acid triesters and jigrimes; triglimes; sulfolanes such as sulfolanes and methyl sulfoxides; oxazolidinones such as 3-methyl-2-oxazolidinone; 1,3-propanesulton, 1,4 -Sultons such as butane sulton and nafta sulton may be further contained. These substances may be used alone or in combination.

The carbonic acid ester in the solvent may be oxidatively decomposed by charging and discharging in the vicinity of the positive electrode 100 to generate carbon dioxide gas. The residual carbon dioxide gas in the cell may cause various troubles (increasing the distance between the positive electrode 100 and the negative electrode 200 or increasing the internal pressure of the cell (pressure in the space closed by the exterior material 400)). In this embodiment, such obstacles can be reduced.

The electrolytic solution may further contain an additive, and the additive is, for example, a sulfonic acid ester such as a cyclic sulfonic acid ester.

The details of the laminated body 12 will be described with reference to FIG.

The laminated body 12 includes a plurality of positive electrodes 100, a plurality of negative electrodes 200, and a separator 300. The plurality of positive electrodes 100 and the plurality of negative electrodes 200 are alternately laminated. In the example shown in FIG. 2, the separator 300 is folded in a zigzag so that a part of the separator 300 is located between the adjacent positive electrode 100 and the negative electrode 200. In another example, a plurality of separators 300 separated from each other may be located between the adjacent positive electrode 100 and the negative electrode 200.

The details of each of the positive electrode 100, the negative electrode 200, and the separator 300 will be described with reference to FIG.

The positive electrode 100 includes a current collector 110 and an active material layer 120 (first active material layer 122 and second active material layer 124). The current collector 110 has a first surface 112 and a second surface 114. The second surface 114 is on the opposite side of the first surface 112. The first active material layer 122 is on the first surface 112 of the current collector 110. The second active material layer 124 is on the second surface 114 of the current collector 110.

The current collector 110 may be formed of, for example, aluminum, stainless steel, nickel, titanium, or an alloy thereof. The shape of the current collector 110 may be, for example, foil, flat plate or mesh.

The active material layer 120 (first active material layer 122 and second active material layer 124) contains active material particles, a binder resin, and a conductive auxiliary agent.

The active material particles contained in the active material layer 120 (first active material layer 122 and second active material layer 124) are Li _a Ni _b M _1-b O ₂ (M is Co, Mn, Al, Ti, Zr. , At least one element selected from Na, Ba and Mg.). Li _a Ni _b M _1-b O ₂ is, for example,
Lithium-nickel composite oxide;
Lithium-nickel-A1 composite oxide (A1 is one of cobalt, manganese, aluminum, titanium, zirconium, sodium, barium and magnesium);
Lithium-nickel-B1-B2 composite oxide (each of B1 and B2 is one of cobalt, manganese, aluminum, titanium, zirconium, sodium, barium and magnesium; B1 and B2 are different from each other);
Lithium-nickel-C1-C2-C3 composite oxides (each of C1 to C3 is one of cobalt, manganese, aluminum, titanium, zirconium, sodium, barium and magnesium. C1 to C3 are different from each other. );
Lithium-nickel-D1-D2-D3-D4 composite oxide (each of D1 to D4 is one of cobalt, manganese, aluminum, titanium, zirconium, sodium, barium and magnesium. D1 to C4 are each other. different.);
Lithium-nickel-E1-E2-E3-E4-E5 composite oxide (each of E1 to E5 is one of cobalt, manganese, aluminum, titanium, zirconium, sodium, barium and magnesium. E1 to E5 are , Different from each other.);
Lithium-nickel-F1-F2-F3-F4-F5-F6 composite oxide (each of F1 to F6 is one of cobalt, manganese, aluminum, titanium, zirconium, sodium, barium and magnesium. F1 to F6 are different from each other.);
Lithium-nickel-G1-G2-G3-G4-G5-G6-G7 composite oxide (each of G1 to G7 is one of cobalt, manganese, aluminum, titanium, zirconium, sodium, barium and magnesium. G1 to G7 are different from each other.); Or is a lithium-nickel-cobalt-manganese-aluminum-titanium-zirconium-sodium-barium-magnesium composite oxide. The composition ratio a of Li _a Ni _b M _1-b O ₂ is, for example, 0.95 ≦ a ≦ 1.05. The composition ratio b of Li _a Ni _b M _1-b O ₂ can be appropriately determined according to, for example, the energy density of the battery 10. The energy density of the battery 10 increases with a large composition ratio b. The composition ratio b is, for example, b ≧ 0.50, preferably b ≧ 0.80. In another example, the active material contained in the active material layer 120 (first active material layer 122 and second active material layer 124) is lithium and a transition metal such as a lithium-cobalt composite oxide and a lithium-manganese composite oxide. composite _oxides; TiS 2, FeS, transition metal sulfides such as _{_{_{_{MoS 2; MnO, V 2 O}}}} 5, V 6 O 13, TiO transition metal oxides such as _2, a olivine-type lithium phosphorus oxides such as May be good. The olivine-type lithium phosphorus oxide is, for example, at least one element in the group consisting of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb and Fe. It contains lithium, phosphorus, and oxygen. These compounds may be those in which some elements are partially replaced with other elements in order to improve their properties. These substances may be used alone or in combination.

The density of the active material contained in the active material layer 120 (the first active material layer 122 and the second active material layer 124) is, for example, 2.0 g / cm ³ or more and 4.0 g / cm ³ or less, preferably 2.4 g. / cm ³ or more 3.8 g / cm ³ or less, more preferably 2.8 g / cm ³ or more 3.6 g / cm ³ or less.

The active material particles contained in the active material layer 120 (the first active material layer 122 and the second active material layer 124) have, for example, a specific surface area of 0.25 m ² / g or more and 1.45 m ² / g or less. You may.

The thickness of the active material layer (first active material layer 122 or second active material layer 124) on one of the two surfaces (first surface 112 and second surface 114) of the current collector 110 is, for example, a battery. It can be appropriately determined according to the rate of 10. The rate of the battery 10 increases as the thickness becomes thinner. The thickness is, for example, 60 μm or less, preferably 50 μm or less, and more preferably 40 μm or less.

The total thickness of the active material layers (first active material layer 122 and second active material layer 124) on both sides (first surface 112 and second surface 114) of the current collector 110 is, for example, the rate of the battery 10. It can be determined as appropriate. The rate of the battery 10 increases as the thickness becomes thinner. The thickness is, for example, 120 μm or less, preferably 100 μm or less, and more preferably 80 μm or less.

The active material layer 120 (first active material layer 122 and second active material layer 124) can be manufactured, for example, as follows. First, the active material, the binder resin and the conductive additive are dispersed in an organic solvent to prepare a slurry. The organic solvent is, for example, N-methyl-2-pyrrolidone (NMP). Next, this slurry is applied onto the first surface 112 of the current collector 110, the slurry is dried, and if necessary, pressing is performed to perform the active material layer 120 (first active material layer) on the current collector 110. 122) is formed. The second active material layer 124 can also be formed in the same manner.

The binder resin contained in the active material layer 120 (the first active material layer 122 and the second active material layer 124) is, for example, polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF).

The amount of the binder resin contained in the active material layer 120 (the first active material layer 122 or the second active material layer 124) can be appropriately determined. The first active material layer 122 has, for example, 0.1 part by mass or more and 10.0 parts by mass or less, preferably 0.5 parts by mass or more and 5.0 with respect to the total mass of 100 parts by mass of the first active material layer 122. It contains a binder resin of 2.0 parts by mass or more, more preferably 4.0 parts by mass or less by mass or less. The same applies to the second active material layer 124.

The conductive additive contained in the active material layer 120 (the first active material layer 122 and the second active material layer 124) is, for example, carbon black, Ketjen black, acetylene black, natural graphite, artificial graphite, carbon fiber and the like. .. The graphite may be, for example, scaly graphite or spheroidal graphite. These substances may be used alone or in combination.

The amount of the conductive additive contained in the active material layer 120 (first active material layer 122 or second active material layer 124) can be appropriately determined according to, for example, the cycle characteristics of the battery 10. The cycle characteristics of the battery 10 improve as the amount of the conductive auxiliary agent in the active material layer 120 increases. The first active material layer 122 has, for example, 3.0 parts by mass or more and 8.0 parts by mass or less, preferably 5.0 parts by mass or more and 6.0 parts by mass with respect to the total mass of 100 parts by mass of the first active material layer 122. Contains less than parts by mass of conductive aid. The same applies to the second active material layer 124.

The active material particles of the first active material layer 122 or the second active material layer 124 may contain lithium hydroxide (LiOH). Lithium hydroxide is a raw material for active material particles. Lithium hydroxide may remain as an impurity in the active material particles after the process of producing the active material particles. The active material particles may contain, for example, 0.43 parts by mass or more or 0.52 parts by mass or more of lithium hydroxide with respect to 100 parts by mass of the total mass of the active material particles.

The negative electrode 200 includes a current collector 210 and an active material layer 220 (first active material layer 222 and second active material layer 224). The current collector 210 has a first surface 212 and a second surface 214. The second surface 214 is on the opposite side of the first surface 212. The first active material layer 222 is on the first surface 212 of the current collector 210. The second active material layer 224 is on the second surface 214 of the current collector 210.

The current collector 210 may be formed of, for example, copper, stainless steel, nickel, titanium, or an alloy thereof. The shape of the current collector 210 may be, for example, foil, flat plate or mesh.

The active material layer 220 (first active material layer 222 and second active material layer 224) contains an active material and a binder resin. The active material layer 220 may further contain a conductive auxiliary agent, if necessary.

The active material contained in the active material layer 220 (the first active material layer 222 and the second active material layer 224) is, for example, graphite, amorphous carbon, diamond-like carbon, fullerene, carbon nanotube, carbon nanohorn which occludes lithium. Carbon materials such as carbon materials; lithium-based metal materials such as lithium metals and lithium alloys; Si-based materials such as Si, SiO ₂ , SiO _x (0 <x ≦ 2), Si-containing composite materials; It is a sex polymer material or the like. These substances may be used alone or in combination. In one example, the active material layer 220 (first active material layer 222 and second active material layer 224) is a first group of graphite particles (for example, natural graphite) having a first average particle size and a first average hardness. It may contain a second group of graphite particles (eg, natural graphite) having a 2 average particle size and a 2nd average hardness. The second average particle size may be smaller than the first average particle size, the second average hardness may be higher than the first average hardness, and the total mass of the graphite particles in the second group is that of the graphite particles in the first group. It may be smaller than the total mass, and the total mass of the graphite particles in the second group may be, for example, 20 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the total mass of the graphite particles in the first group. ..

The density of the active material contained in the active material layer 220 (the first active material layer 222 and the second active material layer 224) is, for example, 1.2 g / cm ³ or more and 2.0 g / cm ³ or less, preferably 1.3 g. / Cm ³ or more and 1.9 g / cm ³ or less, more preferably 1.4 g / cm ³ or more and 1.8 g / cm ³ or less.

The thickness of the active material layer (first active material layer 222 or second active material layer 224) on one of both surfaces (first surface 212 and second surface 214) of the current collector 210 is, for example, a battery. It can be appropriately determined according to the rate of 10. The rate of the battery 10 increases as the thickness becomes thinner. The thickness is, for example, 60 μm or less, preferably 55 μm or less, and more preferably 50 μm or less.

The total thickness of the active material layers (first active material layer 222 and second active material layer 224) on both sides (first surface 212 and second surface 214) of the current collector 210 is, for example, the rate of the battery 10. It can be determined as appropriate. The rate of the battery 10 increases as the thickness becomes thinner. The thickness is, for example, 120 μm or less, preferably 110 μm or less, and more preferably 100 μm or less.

The active material layer 220 (first active material layer 222 and second active material layer 224) can be manufactured, for example, as follows. First, the active material and the binder resin are dispersed in a solvent to prepare a slurry. The solvent may be, for example, an organic solvent such as N-methyl-2-pyrrolidone (NMP), or water. Next, this slurry is applied onto the first surface 212 of the current collector 210, the slurry is dried, and if necessary, a press is performed to perform an active material layer 220 (first active material layer) on the current collector 210. 222) is formed. The second active material layer 224 can also be formed in the same manner.

The binder resin contained in the active material layer 220 (the first active material layer 222 and the second active material layer 224) is, for example, polyvinylidene fluoride (PVDF) or the like when an organic solvent is used as the solvent for obtaining the slurry. It can be a binder resin, and when water is used as a solvent for obtaining a slurry, it can be, for example, a rubber-based binder (for example, SBR (styrene-butadiene rubber)) or an acrylic-based binder resin. Such an aqueous binder resin may be in the form of an emulsion. When water is used as the solvent, it is preferable to use an aqueous binder and a thickener such as CMC (carboxymethyl cellulose) in combination.

The amount of the binder resin contained in the active material layer 220 (the first active material layer 222 or the second active material layer 224) can be appropriately determined. The first active material layer 222 is, for example, 0.1 part by mass or more and 10.0 parts by mass or less, preferably 0.5 parts by mass or more and 8.0 with respect to the total mass of 100 parts by mass of the first active material layer 222. It contains a binder resin of 1 part by mass or less, more preferably 1.0 part by mass or more and 5.0 parts by mass or less, and even more preferably 1.0 part by mass or more and 3.0 parts by mass or less. The same applies to the second active material layer 224.

The separator 300 includes a base material 310 and an insulating layer 320 (first insulating layer 322 and second insulating layer 324). The base material 310 has a first surface 312 and a second surface 314. The second surface 314 is on the opposite side of the first surface 312. The first insulating layer 322 is on the first surface 312 of the base material 310. The second insulating layer 324 is on the second surface 314 of the base material 310.

In the example shown in FIG. 3, the separator 300 includes an insulating layer 320 (first insulating layer 322 and second insulating layer 324) on both surfaces (first surface 312 and second surface 314) of the base material 310. In another example, the separator 300 may include the insulating layer 320 only on one of the two surfaces (first surface 312 and second surface 314) of the base material 310.

The separator 300 has a function of electrically insulating the positive electrode 100 and the negative electrode 200 and allowing ions (for example, lithium ions) to pass therethrough. The separator 300 can be, for example, a porous separator.

The shape of the separator 300 can be appropriately determined according to the shape of the positive electrode 100 or the negative electrode 200, and can be, for example, a rectangle.

The base material 310 preferably contains a resin layer containing a heat-resistant resin. The resin layer contains a heat-resistant resin as a main component, and specifically, 50 parts by mass or more, preferably 70 parts by mass or more, and more preferably 90 parts by mass with respect to 100 parts by mass of the total mass of the resin layer. The above heat-resistant resin is contained, and 100 parts by mass of the heat-resistant resin may be contained with respect to 100 parts by mass of the total mass of the resin layer. The resin layer may be a single layer, or may be two or more types of layers.

Heat-resistant resins include, for example, polyethylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, poly-m-phenylene terephthalate, poly-p-phenylene isophthalate, polycarbonate, polyester carbonate, aliphatic polyamide, total aromatic polyamide, and semi-aroma. Aromatic polyamide, total aromatic polyester, polyphenylene sulfide, polyparaphenylene benzobisoxazole, polyimide, polyarylate, polyetherimide, polyamideimide, polyacetal, polyether ether ketone, polysulfone, polyether sulfone, fluororesin, poly One or more selected from ether nitrile, modified polyphenylene ether and the like.

The insulating layer 320 (first insulating layer 322 and second insulating layer 324) can be manufactured, for example, as follows. First, a solution is prepared by dispersing magnesium hydroxide particles and a resin in a solvent. The solvent is, for example, water, alcohols such as ethanol, N-methylpyrrolidone (NMP), toluene, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and the like. Next, a solution is applied onto the first surface 312 of the base material 310 to form the insulating layer 320 (first insulating layer 322). The second insulating layer 324 can also be formed in the same manner.

The magnesium hydroxide particles may have, for example, a specific surface area of 4.0 m ² / g or more and 8.0 m ² / g or less.

When the electrolytic solution contains a sulfonic acid ester, the sulfonic acid ester may contain 5.0 parts by mass or more of sulfonic acid groups with respect to 100 parts by mass of the total mass of the magnesium hydroxide particles. The sulfonic acid ester is easily adsorbed on the magnesium hydroxide particles. Therefore, it is preferable that the ratio of the mass of the sulfonic acid ester to the mass of the magnesium hydroxide particles is relatively large.

The resin contained in the insulating layer 320 (the first insulating layer 322 and the second insulating layer 324) is, for example, an aromatic polyamide resin such as a meta-aromatic polyamide or a para-aromatic polyamide; carboxymethyl cellulose (CMC) or the like. Cellular resin; acrylic resin; fluororesin such as polyvinylidene fluoride (PVDF); etc. Among these, aromatic polyamide resins are preferable, and meta-aromatic polyamides are more preferable. These substances may be used alone or in combination.

The thickness of the base material 310 can be appropriately determined, and can be, for example, 5.0 μm or more and 10.0 μm or less, preferably 6.0 μm or more and 10.0 μm or less.

The total thickness of the first insulating layer 322 and the thickness of the second insulating layer 324 can be appropriately determined, for example, 10.0 μm or more and 20.0 μm or less, preferably 12.5 μm or more and 17.5 μm or less. Can be.

The thickness of the separator 300 can be appropriately determined, and can be, for example, 15.0 μm or more and 30.0 μm or less, preferably 16.0 μm or more and 27.5 μm or less.

In the example shown in FIG. 3, in the positive electrode 100, the negative electrode 200, and the separator 300, the first surface 112 of the positive electrode 100 faces the first surface 312 of the separator 300, and the first surface 212 of the negative electrode 200 is the second surface of the separator 300. They overlap each other so as to face surface 314.

(Example 1)
The battery 10 was manufactured as follows.

The positive electrode 100 was formed as follows. First, the following materials were dispersed in an organic solvent to prepare a slurry.
Active material particles: 94.0 parts by mass of lithium nickel-containing composite oxide (Chemical formula: Li _1.01 (Ni _0.80 Co _0.15 Al _0.05 ) O ₂ ) (Active material particles are of active material particles. It contains 0.43 parts by mass of lithium hydroxide (LiOH) with respect to 100 parts by mass of the total mass.
Conductive aid: 2.0 parts by mass of spheroidal graphite and 1.0 parts by mass of scaly graphite Binder resin: 3.0 parts by mass of polyvinylidene fluoride (PVDF)
Next, this slurry is applied on both sides (first surface 112 and second surface 114) of the aluminum foil (current collector 110), the slurry is dried, pressed, and the active material layer 120 (first active surface) is carried out. The material layer 122 and the second active material layer 124) were formed. Details of the current collector 110, the first active material layer 122, and the second active material layer 124 are as follows.
(Current collector 110)
Thickness: 15 μm
(1st active material layer 122)
Density: 3.35 g / cm ³
Thickness: 36.6 μm
Metsuke of active material particles A1: 115.1 g / m ²
Specific surface area of active material particles S1 _m : 0.25 m ² / g
(Second active material layer 124)
Density: 3.35 g / cm ³
Thickness: 36.6 μm
Metsuke of active material particles A1: 115.1 g / m ²
Specific surface area of active material particles S1 _m : 0.25 m ² / g

The negative electrode 200 was formed as follows. First, the following materials were dispersed in water to prepare a slurry.
Active material: 77.36 parts by mass of natural graphite (average particle size: 16.0 μm) and 19.34 parts by mass of natural graphite (average particle size: 10.5 μm)
Conductive aid: 0.3 parts by mass of spheroidal graphite Binder resin: 2.0 parts by mass of styrene-butadiene rubber (SBR)
Thickener: 1.0 parts by mass of carboxymethyl cellulose (CMC)
Next, this slurry is applied on both sides (first surface 212 and second surface 214) of the copper foil (current collector 210), the slurry is dried, pressed, and the active material layer 220 (first active surface) is carried out. The material layer 222 and the second active material layer 224) were formed. Details of the current collector 210, the first active material layer 222, and the second active material layer 224 are as follows.
(Current collector 210)
Thickness: 8 μm
(1st active material layer 222)
Density: 1.55 g / cm ³
Thickness: 50.0 μm
(Second active material layer 224)
Density: 1.55 g / cm ³
Thickness: 50.0 μm

The separator 300 was formed as follows. First, the following materials were dispersed in a solvent to prepare a solution.
Inorganic filler: 75 parts by mass of magnesium hydroxide Resin: 25 parts by mass of meta-aromatic polyamide Next, this solution is applied on both sides (first surface 312 and second surface 314) of a polyethylene film (base material 310). The insulating layer 320 (first insulating layer 322 and second insulating layer 324) was formed. Details of the base material 310, the first insulating layer 322, and the second insulating layer 324 are as follows.
(Base material 310)
Thickness: 6.0 μm
(First Insulation Layer 322)
Thickness: 8.0 μm
Metsuke of magnesium hydroxide particles A2: 4.8 g / m ²
Specific surface area of magnesium hydroxide particles S2 _m : 6.1 m ² / g
(Second insulation layer 324)
Thickness: 8.0 μm
Metsuke of magnesium hydroxide particles A2: 4.8 g / m ²
Specific surface area of magnesium hydroxide particles S2 _m : 6.1 m ² / g

As shown in FIG. 2, the laminated body 12 was formed so that 14 positive electrodes 100 and 14 negative electrodes 200 were alternately arranged and the separator 300 was folded back in a zigzag manner.

As shown in FIG. 1, the battery 10 was manufactured by accommodating the laminate 12 together with the electrolytic solution in the exterior material 400. The electrolytic solution contains the following supporting salts, solvents and additives.
Supporting salt: LiPF ₆
Solvents: 30% by volume ethylene carbonate (EC), 60% by volume diethyl carbonate (DEC) and 10% by volume methyl ethyl carbonate (MEC).
Additive: Cyclic sulfonic acid ester (Cyclic sulfonic acid ester contains 0.27 parts by mass of sulfonic acid groups with respect to 100 parts by mass of the total mass of the active material particles of the first active material layer 122 or the second active material layer 124. Included), 1.5 parts by mass of vinylene carbonate with respect to 100 parts by mass of the total mass of the electrolytic solution and 1.0 part by mass of fluoroethylene carbonate with respect to 100 parts by mass of the total mass of the electrolytic solution.

The reduction of residual gas was evaluated for the battery 10. Specifically, initial charging was performed at a temperature of 25 ° C. with a constant current of a charging rate of 0.15 C and a charge termination voltage of 4.2 V and 2.3 A. The volume V ₀ (cc) of the battery 10 before the initial charge and the volume V _charge (cc) of the battery 10 after the initial charge were measured. The reduction of residual gas was evaluated according to the following criteria.
◯: V _charge / V ₀ × 100 was less than 115% ×: V _charge / V ₀ × 100 was 115% or more

The cycle characteristics of the battery 10 were evaluated. Specifically, a cycle test was carried out at a temperature of 45 ° C. with a charge rate of 1.0 C, a discharge rate of 1.0 C, a charge end voltage of 4.2 V, and a discharge end voltage of 2.5 V. The discharge capacity C ₁₀ (mAh) at the _10th cycle and the discharge capacity C ₅₀₀ (mAh) at the 500th cycle were measured. The cycle characteristics were evaluated according to the following criteria.
◯: C ₅₀₀ / C ₁₀ × 100 was 90% or more ×: C ₅₀₀ / C ₁₀ × 100 was less than 90%

Table 1 shows the conditions of the positive electrode 100, the conditions of the separator 300, the reduction of residual gas, and the cycle characteristics in Example 1.

The conditions of the positive electrode 100 and the conditions of the separator 300 in Examples 2 to 9 and Comparative Examples 1 to 4 are the same as the conditions of the positive electrode 100 and the conditions of the separator 300 in Example 1, except for the points shown in Table 1. And said. In Table 1, "-" in Comparative Example 4 means that the first insulating layer 322 and the second insulating layer 324 do not contain magnesium hydroxide particles.

Table 1 shows the reduction of residual gas and the cycle characteristics in each of Examples 2 to 9 and Comparative Examples 1 to 4.

From the comparison of the results of Examples 1 to 9 and the results of Comparative Examples 1 to 4, the product P2 of the magnesium hydroxide particles having a grain A2 and the specific surface area S2 _m is the product P1 of the active material particles having a grain A1 and a specific surface area S1 _m . It may be 0.7 times or more of (the numerical value (0.7) is rounded to one significant digit). The residual gas in the cell can be reduced according to the relationship between the product P1 and the product P2.

The reason why the residual gas is reduced by the relationship between the product P1 and the product P2 is presumed to be as follows. It is presumed that most of the gas generated by the initial charge is carbon dioxide gas generated by the oxidative decomposition of the carbonic acid ester contained in the electrolytic solution. The product P1 corresponds to the total surface area of the active material particles per unit area, and the product P2 corresponds to the total surface area of the magnesium hydroxide particles per unit area. The larger the product P1, the larger the surface area of the chemical reaction that generates carbon dioxide (that is, the total surface area of the active material particles), and the more carbon dioxide can be generated. On the other hand, as the product P2 is larger, the surface area of the chemical reaction that absorbs carbon dioxide gas (that is, the total surface area of the magnesium hydroxide particles) becomes larger, and the absorption of carbon dioxide gas can be increased. In each of Examples 1 to 9, the surface area of the chemical reaction that absorbs carbon dioxide gas (that is, product P2) has a relatively large ratio to the surface area of the chemical reaction that generates carbon dioxide gas (that is, product P1). As a result, the residual carbon dioxide gas is reduced.

From the results of Examples 1 to 9, the ratio of the thickness of the first insulating layer 322 to the thickness of the base material 310 or the ratio of the thickness of the second insulating layer 324 to the thickness of the base material 310 is 3.8 /. It may be 7.5 or more and 4.0 / 3.0 or less. The residual gas does not depend on the relationship between the thickness of the base material 310 and the thickness of the first insulating layer 322 or the relationship between the thickness of the base material 310 and the thickness of the second insulating layer 324, at least in the above-mentioned range. It will be reduced.

From the comparison of the results of Examples 2, 3, 7 and 8 and the results of Comparative Examples 1, 3 and 4, the active material particles of the first active material layer 122 or the second active material layer 124 are the total mass of the active material particles. It may contain 0.52 parts by mass or more of lithium hydroxide with respect to 100 parts by mass. Specifically, from the comparison of the results of Comparative Example 2 and the results of Comparative Examples 1, 3 and 4, the cycle characteristics tend to deteriorate when the amount of lithium hydroxide is relatively large. However, as compared with the results of Examples 2, 3, 7 and 8 and the results of Comparative Examples 1, 3 and 4, the products P1 and P2 are described above even when the amount of lithium hydroxide is relatively large. When there is a relationship, it can be said that deterioration of cycle characteristics can be reduced.

The reason why the cycle characteristics tend to deteriorate when the amount of lithium hydroxide is relatively large is presumed to be as follows. First, the reaction of lithium hydroxide and carbon dioxide gas deposits high-resistance lithium carbonate (Li ₂ CO ₃ ) on the surface of the positive electrode 100, which can inhibit the intercalation of Li ions on the surface of the positive electrode 100. Secondly, the conductive path formed between the active material particles by the conductive auxiliary agent is blocked by lithium carbonate, and the electron transfer resistance of the positive electrode 100 can be increased. Third, lithium hydroxide between the primary particles of the active material particles can be eluted into the electrolytic solution to form lithium carbonate so as to cover the surface of the secondary particles of the active material particles.

Even when the amount of lithium hydroxide is relatively large, the reason why the deterioration of the cycle characteristics is reduced according to the relationship between the product P1 and the product P2 is presumed to be as follows. As described above, the carbon dioxide gas can be reduced according to the relationship between the product P1 and the product P2. Therefore, the reaction between lithium hydroxide and carbon dioxide can be reduced.

Although the embodiments and examples of the present invention have been described above with reference to the drawings, these are examples of the present invention, and various configurations other than the above can be adopted.

This application claims priority based on Japanese Application Japanese Patent Application No. 2019-042199 filed on March 8, 2019, and incorporates all of its disclosures herein.

10 Battery 12 Laminated body 100 Positive electrode 110 Current collector 112 First surface 114 Second surface 120 Active material layer 122 First active material layer 124 Second active material layer 130 First lead 200 Negative electrode 210 Current collector 212 First surface 214 2nd surface 220 Active material layer 222 1st active material layer 224 2nd active material layer 230 2nd lead 300 Separator 310 Base material 312 1st surface 314 2nd surface 320 Insulating layer 322 1st insulating layer 324 2nd insulating layer 400 Exterior material

Claims

A positive electrode including a current collector having a first surface and a second surface opposite to the first surface, and a first active material layer located on the first surface of the current collector.
The first insulating layer of the positive electrode facing the first active material layer and
Including
The first active material layer is Li a Ni b M 1-b O 2 (0.95 ≦ a ≦ 1.05, b ≧ 0.50, M is Co, Mn, Al, Ti, Zr, Na, It contains active material particles represented by (one or more elements selected from Ba and Mg).
The first insulating layer contains magnesium hydroxide particles and contains magnesium hydroxide particles.
A battery in which the product of the grain size and the specific surface area of the magnesium hydroxide particles is 0.7 times or more the product of the grain size and the specific surface area of the active material particles.
In the battery according to claim 1,
The separator facing the positive electrode and
A negative electrode facing the separator from the side opposite to the positive electrode,
Including
The separator comprises a first insulating layer, a second insulating layer facing the negative electrode, and a base material located between the first insulating layer and the second insulating layer.
In the battery according to claim 1 or 2.
The magnesium hydroxide particles are a battery having a specific surface area of 4.0 m 2 / g or more and 8.0 m 2 / g or less.
In the battery according to any one of claims 1 to 3,
The active material particles are a battery further containing 0.52 parts by mass or more of lithium hydroxide with respect to 100 parts by mass of the total mass of the active material particles.
In the battery according to any one of claims 1 to 4.
Further containing an electrolytic solution containing a sulfonic acid ester,
The sulfonic acid ester is a battery containing 5.0 parts by mass or more of sulfonic acid groups with respect to 100 parts by mass of the total mass of the magnesium hydroxide particles.
In the battery according to any one of claims 1 to 5,
The first insulating layer is a battery further containing an aromatic polyamide.