TW202002383A - Secondary battery and manufacturing method therefor - Google Patents

Abstract

One aspect of the present invention is a secondary battery provided with a positive electrode, an electrolyte layer, and a negative electrode, wherein: the positive electrode, the electrolyte layer, and the negative electrode are stacked in this order and are in a pressure application state in which pressure is applied in the stacked direction; and the secondary battery is further provided with a holding means for holding the pressure application state.

Description

Secondary battery and its manufacturing method

The present disclosure relates to a secondary battery and a manufacturing method thereof.

In recent years, due to the popularization of portable electronic devices, electric vehicles, etc., high-performance secondary batteries are required. Among them, lithium secondary batteries have high energy density, and therefore are used as power sources for portable electronic devices, electric vehicles, and the like. High safety is required for lithium secondary batteries, and as its means, the development of all-solid-state batteries is progressing.

In an all-solid-state battery, a layer (electrolyte layer) of a solid electrolyte such as a polymer electrolyte or an inorganic solid electrolyte is provided on the electrode mixture layer instead of the electrolytic solution (for example, Patent Document 1). In such an all-solid-state battery, a solvent is sometimes added to the electrolyte layer. For example, Patent Literature 2 discloses a secondary battery that contains an ionic liquid in an electrolyte layer such as a polymer electrolyte. [Prior Technical Literature] (Patent Literature)

Patent Document 1: Japanese Patent Laid-Open No. 2006-294326 Patent Literature 2: International Publication No. 2011/037060

[Problems to be solved by the invention] For the secondary battery as described above, higher performance is required, and it is desired to develop a lithium secondary battery whose initial discharge capacity (initial capacity) is as close as possible to the design capacity, that is, so-called initial characteristics are excellent. Therefore, an object of the present invention is to provide a secondary battery and a method for manufacturing the same, which has excellent initial characteristics. [Technical means to solve the problem]

An aspect of the present invention is a secondary battery including a positive electrode, an electrolyte layer, and a negative electrode, wherein the positive electrode, the electrolyte layer, and the negative electrode are stacked in this order, and are in a pressurized state in which pressure is applied in the stacking direction, and The secondary battery further includes holding means for holding the pressurized state.

The positive electrode, the electrolyte layer, and the negative electrode can be applied with a pressure of 0.7 MPa or more in the stacking direction.

Another aspect of the present invention is a method for manufacturing a secondary battery, including: a pressurizing step that applies pressure to a laminate in a stacking direction, the laminate having a positive electrode, an electrolyte layer, and a negative electrode in sequence; and, holding In the step, it is provided with holding means for holding the pressurized state of the laminated body to which the pressure is applied.

In the pressurizing step, pressure may be applied to the layered body at 0.7 MPa or more in the layering direction. The above manufacturing method may further include a step of heating the laminate at 50° C. or higher after the holding step.

In the above aspects, the electrolyte layer may contain polymers, oxide particles, electrolyte salts, and ionic solutions. The positive electrode includes a positive electrode current collector and a positive electrode mixture layer. The positive electrode mixture layer is provided on the positive electrode current collector, and the positive electrode mixture layer may contain a positive electrode active material and an ionic liquid. The negative electrode includes a negative electrode current collector and a negative electrode mixture layer, the negative electrode mixture layer is provided on the negative electrode current collector, and the negative electrode mixture layer may contain a negative electrode active material and an ionic liquid. [Efficacy of invention]

According to the present invention, it is possible to provide a secondary battery and a method for manufacturing the same, which has excellent initial characteristics.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings as appropriate. However, the present invention is not limited to the following embodiments. In the following embodiments, the constituent elements (including steps, etc.) are not necessary unless specifically stated otherwise. The dimensions of the constituent elements in each figure are conceptual dimensions, and the relative relationship of the dimensions between the constituent elements is not limited to those shown in each figure. In the description of the drawings, the same elements are given the same reference signs, and redundant explanations are omitted.

The numerical values and ranges in this specification are not intended to limit the present invention. The numerical range indicated by "~" in this specification means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical range described in stages in this specification, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value described in other stages. In addition, in the numerical range described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples.

Fig. 1 is an exploded perspective view showing a secondary battery according to an embodiment. As shown in FIG. 1, a secondary battery 1 according to an embodiment includes a laminated battery 2 and a holding member 3 for holding the laminated battery 2.

The laminated battery 2 includes an electrode group 4 composed of a positive electrode, a negative electrode, and an electrolyte layer. The battery group 5 has a bag shape and accommodates the electrode group 4. The positive electrode and the negative electrode are provided with a positive electrode collector terminal 6 and a negative electrode collector terminal 7, respectively. The positive electrode collector terminal 6 and the negative electrode collector terminal 7 each protrude from the inside of the battery case 5 to the outside in such a manner that the positive electrode and the negative electrode can be electrically connected to the outside of the laminated battery 2.

The battery case 5 can be formed using, for example, a laminated film. The laminated film may be, for example, a laminated film laminated in the following order: a polymer film such as polyethylene terephthalate (PET) film; a metal foil such as aluminum, copper, or stainless steel; and, polypropylene Etc. sealant layer.

The clamping member 3 is composed of a pair of substrates (8, 8), screws (bolts) 9 and nuts 10, and the screws 9 can fasten the substrates (8, 8) to each other. For example, a plurality of screws 9 are mounted on one of the substrates 8, and a plurality of holes 8a are formed on the other substrate for inserting the plurality of screws 9 respectively. The nut 10 and the screw 9 inserted into the hole 8a are screwed together, thereby fastening the substrates (8, 8) to each other.

FIG. 2 is a schematic cross-sectional view showing the secondary battery 1. As shown in FIG. 2, the electrode group 4 in the laminated battery 2 includes a positive electrode 41, an electrolyte layer 42 and a negative electrode 43 in this order. The positive electrode 41 includes a positive electrode current collector 44 and a positive electrode mixture layer 45. The positive electrode mixture layer 45 is provided on the positive electrode current collector 44. The negative electrode 43 includes a negative electrode current collector 46 and a negative electrode mixture layer 47. The negative electrode mixture layer 47 is provided on the negative electrode current collector 46.

The positive electrode current collector 44 can be formed using aluminum, stainless steel, titanium, or the like. Specifically, the positive electrode current collector 44 may be, for example, an aluminum perforated foil having holes with a pore diameter of 0.1 to 10 mm, expanded metal, expanded metal plate, or the like. In addition to the above materials, the positive electrode current collector 44 can be formed of any material as long as it does not cause changes such as dissolution or oxidation during the use of the battery, and its shape, manufacturing method, and the like are not limited.

The thickness of the positive electrode current collector 44 may be 10 μm or more or 100 μm or less. From the viewpoint of reducing the overall volume of the cathode 41, the thickness of the cathode current collector 44 is preferably 10 μm or more and 50 μm or less. From the viewpoint of winding the positive electrode with a small curvature when forming the battery, it is more preferable 10 μm or more and 20 μm or less.

In one embodiment, the positive electrode mixture layer 45 contains a positive electrode active material and an ionic liquid. The positive electrode active material may be a lithium transition metal compound such as lithium transition metal oxide or lithium transition metal phosphate.

The lithium transition metal oxide may be, for example, lithium manganate, lithium nickelate, lithium cobaltate, or the like. Lithium transition metal oxides can be substituted with one or more than two other transition metals or metals (typical elements) such as magnesium (Mg), aluminum (Al), etc. to replace lithium manganate, lithium nickelate, lithium cobaltate, etc. Lithium transition metal oxides derived from transition metals such as manganese (Mn), nickel (Ni), and cobalt (Co). That is, the lithium transition metal oxide may be a compound represented by LiM ¹ O ₂ or LiM ¹ O ₄ (M ¹ contains at least one transition metal). Specifically, the lithium transition metal oxide may be Li(Co _1/3 Ni _1/3 Mn _1/3 )O ₂ , LiNi _1/2 Mn _1/2 O ₂ , LiNi _1/2 Mn _3/2 O _4th .

From the viewpoint of further increasing the energy density, the lithium transition metal oxide is preferably a compound represented by the following formula (1). Li _a Ni _b Co _c M ² _d O _{2 + e} (1) In formula (1), M ² is at least one selected from the group consisting of Al, Mn, Mg, and Ca, a, b, c , D, and e are each a number that satisfies 0.2≦a≦1.2, 0.5≦b≦0.9, 0.1≦c≦0.4, 0≦d≦0.2, −0.2≦e≦0.2, and b+c+d=1.

Lithium transition metal phosphate, which can be LiFePO ₄ , LiMnPO ₄ , LiMn _x M ³ _{1 - x} PO ₄ (0.3≦x≦1, M ³ is selected from Fe, Ni, Co, Ti, Cu, Zn, Mg and Zr At least one element in the group formed) etc.

The positive electrode active material may be primary particles that have not been granulated or secondary particles that have been granulated.

The particle size of the positive electrode active material is adjusted to be equal to or less than the thickness of the positive electrode mixture layer 45. When there are coarse particles having a particle diameter greater than the thickness of the positive electrode mixture layer 45 in the positive electrode active material, the coarse particles are removed in advance by sieve classification, air flow classification, etc., thereby screening for particles having a particle diameter less than the thickness of the positive electrode mixture layer 45 Positive active material.

The average particle size of the positive electrode active material is preferably 0.1 μm or more, and more preferably 1 μm or more. The average particle size of the positive electrode active material is preferably 30 μm or less, and more preferably 25 μm or less. The average particle diameter of the positive electrode active material is the particle diameter (D ₅₀ ) when the ratio (volume fraction) to the volume of the entire positive electrode active material is 50%. The average particle size (D ₅₀ ) of the positive electrode active material is obtained by using a laser scattering particle size measuring device (for example, Microtrac) and measuring the suspension according to the laser scattering method. This suspension is to suspend the positive electrode active material in Get in the water.

The content of the positive electrode active material may be 70% by mass or more, 80% by mass or more, or 90% by mass based on the total amount of the positive electrode mixture layer. The content of the positive electrode active material may be 99% by mass or less based on the total amount of the positive electrode mixture layer.

The ionic liquid contains the following anionic components and cationic components. In addition, the ionic liquid in this embodiment is a substance that is liquid at -20°C or higher.

The anionic component of the ionic liquid is not particularly limited, and may be halogen anions such as Cl ^－ , Br ^－ , I ^－ ; inorganic anions such as BF ₄ ^－ , N(SO ₂ F) ₂ ^－ ; B(C ₆ H ₅ ) ₄ ^－ , CH ₃ SO ₂ O ^－ , CF ₃ SO ₂ O ^－ , N(SO ₂ C ₄ F ₉ ) ₂ ^－ , N(SO ₂ CF ₃ ) ₂ ^－ , N(SO ₂ C ₂ F ₅ ) ₂ ^－ Such as organic anions. The anion component of the ionic liquid preferably contains at least one kind of anion component represented by the following general formula (I). _{N (SO 2 C m F 2m} + 1) (SO 2 C n F + 1 2n) - (I) m and n are each independently an integer of 0 to 5. m and n may be the same as or different from each other, preferably the same as each other.

The anion component represented by the formula (I), for example, N(SO ₂ C ₄ F ₉ ) ₂ ^－ , N(SO ₂ F) ₂ ^－ , N(SO ₂ CF ₃ ) ₂ ^－ and N(SO ₂ C ₂ F ₅ ) ₂ ^- . From the viewpoint of relatively low viscosity and further improvement of ionic conductivity, and also further improvement of charge and discharge characteristics, the anionic component of the ionic liquid is more preferably selected from N(SO ₂ C ₄ F ₉ ) ₂ ^－ , CF ₃ SO ₂ O ^－ , N(SO ₂ F) ₂ ^－ , N(SO ₂ CF ₃ ) ₂ ^－ , and N(SO ₂ C ₂ F ₅ ) ₂ ^－ at least one of the group, which is even better It contains N(SO ₂ F) ₂ ^- .

In addition, the following abbreviations are sometimes used below. [FSI] ^－ : N(SO ₂ F) ^{2 －} , bis(fluorosulfonyl)imide anion [TFSI] ^－ ：N(SO ₂ CF3) ^{2 －} , bis(trifluoromethanesulfonyl)imide anion [BOB ] ^－ ：B(O ₂ C ₂ O ₂ ) ^{2 －} , bis-oxalate boric acid anion [f3C] ^－ ：C(SO ₂ F) ^{3 －} , ginseng (fluorosulfonyl) carbon anion

The cation component of the ionic liquid is preferably selected from the group consisting of chain quaternary onium salt cations, piperidinium salt cations, pyrrolidinium salt cations, pyridinium salt cations and imidazolium cations At least one of them.

式(II)中，R¹¹ ～R¹⁴ 各自獨立地表示碳數為1～20的鏈狀烷基或由R-O-(CH₂ )_n -表示的鏈狀烷氧烷基(R表示甲基或乙基，n表示1～4的整數)，X表示氮原子或磷原子。由R¹¹ ～R¹⁴ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The chain quaternary onium salt cation is, for example, a compound represented by the following formula (II).

In formula (II), R ¹¹ to R ¹⁴ each independently represent a chain alkyl group having 1 to 20 carbon atoms or a chain alkoxyalkyl group represented by RO-(CH ₂ ) _n- (R represents a methyl group or Ethyl, n represents an integer of 1 to 4), X represents a nitrogen atom or a phosphorus atom. The carbon number of the alkyl group represented by R ¹¹ to R ¹⁴ is preferably from 1 to 20, more preferably from 1 to 10, and even more preferably from 1 to 5.

式(III)中，R¹⁵ 和R¹⁶ 各自獨立地表示碳數為1～20的烷基或由R-O-(CH₂ )_n -表示的烷氧烷基(R表示甲基或乙基，n表示1～4的整數)。由R¹⁵ 和R¹⁶ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The piperidinium salt cation is, for example, a six-membered nitrogen-containing cyclic compound represented by the following formula (III).

In formula (III), R ¹⁵ and R ¹⁶ each independently represent an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group represented by RO-(CH ₂ ) _n- (R represents methyl or ethyl, n Represents an integer of 1 to 4). The carbon number of the alkyl group represented by R ¹⁵ and R ¹⁶ is preferably 1-20, more preferably 1-10, and even more preferably 1-5.

式(IV)中，R¹⁷ 和R¹⁸ 各自獨立地表示碳數為1～20的烷基或由R-O-(CH₂ )_n -表示的烷氧烷基(R表示甲基或乙基，n表示1～4的整數)。由R¹⁷ 和R¹⁸ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The pyrrolidinium salt cation is, for example, a five-membered cyclic compound represented by the following formula (IV).

In formula (IV), R ¹⁷ and R ¹⁸ each independently represent an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group represented by RO-(CH ₂ ) _n- (R represents methyl or ethyl, n Represents an integer of 1 to 4). The carbon number of the alkyl group represented by R ¹⁷ and R ¹⁸ is preferably 1-20, more preferably 1-10, and still more preferably 1-5.

式(V)中，R¹⁹ ～R²³ 各自獨立地表示碳數為1～20的烷基、由R-O-(CH₂ )_n -表示的烷氧烷基(R表示甲基或乙基，n表示1～4的整數)、或氫原子。由R¹⁹ ～R²³ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The pyridinium salt cation is, for example, a compound represented by the following formula (V).

In formula (V), R ¹⁹ to R ²³ each independently represent an alkyl group having 1 to 20 carbon atoms, and an alkoxyalkyl group represented by RO-(CH ₂ ) _n- (R represents methyl or ethyl, n Represents an integer of 1 to 4), or a hydrogen atom. The carbon number of the alkyl group represented by R ¹⁹ to R ²³ is preferably 1-20, more preferably 1-10, and still more preferably 1-5.

式(VI)中，R²⁴ ～R²⁸ 各自獨立地表示碳數為1～20的烷基、由R-O-(CH₂ )_n -表示的烷氧烷基(R表示甲基或乙基，n表示1～4的整數)、或氫原子。由R²⁴ ～R²⁸ 表示的烷基的碳數較佳是1～20，更佳是1～10，進一步更佳是1～5。The imidazolium salt cation is, for example, a compound represented by the following formula (VI).

In formula (VI), R ²⁴ to R ²⁸ each independently represent an alkyl group having 1 to 20 carbon atoms, and an alkoxyalkyl group represented by RO-(CH ₂ ) _n- (R represents a methyl group or an ethyl group, n Represents an integer of 1 to 4), or a hydrogen atom. The carbon number of the alkyl group represented by R ²⁴ to R ²⁸ is preferably 1 to 20, more preferably 1 to 10, and still more preferably 1 to 5.

The content of the ionic liquid based on the total amount of the positive electrode mixture layer is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more. The content of the ionic liquid based on the total amount of the positive electrode mixture layer is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

The positive electrode mixture layer 45 may further contain a conductive material, a binder, and the like.

The conductive material is not particularly limited, and may be carbon materials such as graphite, acetylene black, carbon black, carbon fiber, and carbon nanotubes. The conductive material may be a mixture of two or more of the above carbon materials. Based on the total amount of the positive electrode mixture layer, the content of the conductive material may be 0.1% by mass or more, 1% by mass or more, or 3% by mass or more, or 15% by mass or less, 10% by mass or less, or 8% by mass the following.

The binder, which is not particularly limited, may be a polymer consisting of tetrafluoroethylene, vinylidene fluoride, hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate and methyl methacrylate At least one member of the group is used as a monomer unit; rubbers such as styrene-butadiene rubber, isoprene rubber, acrylic rubber, etc. The binder is preferably a copolymer containing tetrafluoroethylene and vinylidene fluoride as structural units, and a copolymer containing vinylidene fluoride and hexafluoropropylene as structural units.

The content of the binder may be 0.5% by mass or more, 1% by mass or more, or 3% by mass or more based on the total amount of the positive electrode mixture layer. The content of the binder may be 20% by mass or less, 15% by mass or less, or 10% by mass based on the total amount of the positive electrode mixture layer.

In ionic liquids, electrolyte salts are soluble. The electrolyte salt may be at least one selected from the group consisting of lithium salt, sodium salt, calcium salt and magnesium salt.

The anion component of the electrolyte salt may be halide ions (I ^－ , Cl ^－ , Br ^－ etc.), SCN ^－ , BF ₄ ^－ , BF ₃ (CF ₃ ) ^－ , BF ₃ (C ₂ F ₅ ) ^－ , PF ₆ ^－ , ClO ₄ ^－ , SbF ₆ ^－ , N(SO ₂ F) ₂ ^－ , N(SO ₂ CF ₃ ) ₂ ^－ , N(SO ₂ C ₂ F ₅ ) ₂ ^－ , B(C ₆ H ₅ ) ₄ ^－ , B(O ₂ C ₂ H ₄ ) ₂ ^－ , C(SO ₂ F) ₃ ^－ , C(SO ₂ CF ₃ ) ₃ ^－ , CF ₃ COO ^－ , CF ₃ SO ₂ O ^－ , C ₆ F ₅ SO ₂ O ^－ , B(O ₂ C ₂ O ₂ ) ₂ ^－ etc. The anion component of the electrolyte salt is preferably an anion component represented by the above formula (I) such as N(SO ₂ F) ₂ ^－ , N(SO ₂ CF ₃ ) ₂ ^－ ; PF ₆ ^－ , BF ₄ ^－ , B _{(O 2 C 2 O 2)} 2 -, or ClO ₄ ^-.

The lithium salt may be selected from LiPF ₆ , LiBF ₄ , Li[FSI], Li[TFSI], Li[f3C], Li[BOB], LiClO ₄ , LiBF ₃ (CF ₃ ), LiBF ₃ (C ₂ F ₅ ), LiBF ₃ (C ₃ F ₇ ), LiBF ₃ (C ₄ F ₉ ), LiC (SO ₂ CF ₃ ) ₃ , LiCF ₃ SO ₂ O, LiCF ₃ COO, and LiRCOO (R is carbon number 1 to 4 At least one of the group consisting of alkyl, phenyl, or naphthyl).

The sodium salt can be selected from NaPF ₆ , NaBF ₄ , Na[FSI], Na[TFSI], Na[f3C], Na[BOB], NaClO ₄ , NaBF ₃ (CF ₃ ), NaBF ₃ (C ₂ F ₅ ), NaBF ₃ (C ₃ F ₇ ), NaBF ₃ (C ₄ F ₉ ), NaC (SO ₂ CF ₃ ) ₃ , NaCF ₃ SO ₂ O, NaCF ₃ COO, and NaRCOO (R is carbon number 1 to 4 At least one of the group consisting of alkyl, phenyl, or naphthyl).

Calcium salt can be selected from Ca(PF ₆ ) ₂ , Ca(BF ₄ ) ₂ , Ca[FSI] ₂ , Ca[TFSI] ₂ , Ca[f3C] ₂ , Ca[BOB] ₂ , Ca(ClO ₄ ) ₂ , Ca[BF ₃ (CF ₃ )] ₂ , Ca[BF ₃ (C ₂ F ₅ )] ₂ , Ca[BF ₃ (C ₃ F ₇ )] ₂ , Ca[BF ₃ (C ₄ F ₉ )] ₂ , Ca[C(SO ₂ CF ₃ ) ₃ ] ₂ , Ca(CF ₃ SO ₂ O) ₂ , Ca(CF ₃ COO) ₂ , and Ca(RCOO) ₂ (R is a C 1-4 alkane Group, phenyl group, or naphthyl group).

The magnesium salt may be selected from Mg(PF ₆ ) ₂ , Mg(BF ₄ ) ₂ , Mg[FSI] ₂ , Mg[TFSI] ₂ , Mg[f3C] ₂ , Mg[BOB] ₂ , Na(ClO ₄ ) ₂ , Mg[BF ₃ (CF ₃ )] ₂ , Mg[BF ₃ (C ₂ F ₅ )] ₂ , Mg[BF ₃ (C ₃ F ₇ )] ₂ , Mg[BF ₃ (C ₄ F ₉ )] ₂ , Mg[C(SO ₂ CF ₃ ) ₃ ] ₂ , Mg(CF ₃ SO ₃ ) ₂ , Mg(CF ₃ COO) ₂ , and Mg(RCOO) ₂ (R is an alkyl group having 1 to 4 carbon atoms , Phenyl, or naphthyl).

Among them, from the viewpoint of dissociation and electrochemical stability, the electrolyte salt is preferably selected from LiPF ₆ , LiBF ₄ , Li[FSI], Li[TFSI], Li[f3C], Li[BOB], LiClO ₄ , LiBF ₃ (CF ₃ ), LiBF ₃ (C ₂ F ₅ ), LiBF ₃ (C ₃ F ₇ ), LiBF ₃ (C ₄ F ₉ ), LiC (SO ₂ CF ₃ ) ₃ , LiCF ₃ SO ₂ O , LiCF ₃ COO, and LiRCOO (R is a C 1-4 alkyl group, phenyl group, or naphthyl group) at least one member, more preferably selected from Li[TFSI], Li[ At least one of the group consisting of FSI], LiPF ₆ , LiBF ₄ , Li[BOB], and LiClO ₄ , further preferably selected from the group consisting of Li[TFSI] and Li[FSI] At least 1 kind.

The thickness of the positive electrode mixture layer 45 may be 10 μm or more, 15 μm or more, or 20 μm or more. The thickness of the positive electrode mixture layer 45 may be 100 μm or less, 80 μm or less, or 70 μm or less. By setting the thickness of the positive electrode mixture layer to 100 μm or less, it is possible to suppress variations in charge and discharge due to the difference in the charge level of the positive electrode active material near the surface of the positive electrode mixture layer 45 and near the surface of the positive electrode current collector 44. all.

The negative electrode current collector 46 may be metal such as aluminum, copper, nickel, stainless steel, or alloy of these metals. In order to be lightweight and have a high weight energy density, the negative electrode current collector 46 is preferably aluminum or its alloy. From the viewpoints of simplicity and cost of processing the thin film, the negative electrode current collector 46 is preferably copper.

The thickness of the negative electrode current collector 46 may be 10 μm or more or 100 μm or less. From the viewpoint of reducing the volume of the entire negative electrode, the thickness of the negative electrode current collector 46 is preferably 10 μm or more and 50 μm or less, and more preferably 10 μm or more from the viewpoint of winding the negative electrode with a small curvature when forming the battery And below 20μm.

In one embodiment, the negative electrode mixture layer 47 contains a negative electrode active material and an ionic liquid.

As the negative electrode active material, a negative electrode active material commonly used in the field of energy devices can be used. Specifically, examples of the negative electrode active material include metal lithium, lithium titanate (Li ₄ Ti ₅ O ₁₂ ), lithium alloys or other metal compounds, carbon materials, metal complexes, organic polymer compounds, etc. . The negative electrode active material may be a single type of these negative electrode active materials, or a mixture of two or more types. Examples of the carbon material include natural graphite (flaky graphite and the like) and graphite such as artificial graphite; amorphous carbon and carbon fiber; and, acetylene black, Ketjen black, channel black, furnace carbon black, and lamp Carbon black such as black and thermal cracked carbon black. From the viewpoint of obtaining a larger theoretical capacity (for example, 500 to 1500 Ah/kg), the negative electrode active material may also be silicon, tin, or a compound containing these elements (oxide, nitride, or alloy with other metals).

From the viewpoint of obtaining a negative electrode with a good balance that suppresses an increase in irreversible capacity accompanying a decrease in particle size and improves electrolyte salt retention, the average particle size (D ₅₀ ) of the negative electrode active material is preferably 1 μm or more It is more preferably 5 μm or more, still more preferably 10 μm or more, and preferably 50 μm or less, more preferably 40 μm or less, and still more preferably 30 μm or less. The average particle diameter (D ₅₀ ) of the negative electrode active material is measured according to the same method as the average particle diameter (D ₅₀ ) of the positive electrode active material.

The content of the negative electrode active material may be 60% by mass or more, 65% by mass or more, or 70% by mass or more based on the total amount of the negative electrode mixture layer. The content of the negative electrode active material may be 99% by mass or less, 95% by mass or less, or 90% by mass or less based on the total amount of the negative electrode mixture layer.

The ionic liquid may be the ionic liquid described above as the ionic liquid contained in the positive electrode mixture layer 45. The content of the ionic liquid based on the total amount of the negative electrode mixture layer is preferably 3% by mass or more, more preferably 5% by mass or more, and still more preferably 10% by mass or more. The content of the ionic liquid based on the total amount of the negative electrode mixture layer is preferably 30% by mass or less, more preferably 25% by mass or less, and still more preferably 20% by mass or less. In the ionic liquid, the same electrolyte salt that can be used in the positive electrode mixture layer 45 described above can be dissolved.

The negative electrode mixture layer 47 may further contain the above-mentioned conductive material, binder, and the like that can be used in the positive electrode mixture layer 45. The content of the conductive material and the binder contained in the negative electrode mixture layer 47 may be the same as the content of the conductive material or the binder in the positive electrode mixture layer 45, respectively.

The thickness of the negative electrode mixture layer 47 may be 10 μm or more, 15 μm or more, or 20 μm or more. The thickness of the negative electrode mixture layer 47 may be 100 μm or less, 80 μm or less, or 70 μm or less.

In one embodiment, the electrolyte layer 42 contains a polymer, oxide particles, electrolyte salt, and ionic liquid.

The polymer preferably has a first structural unit selected from the group consisting of tetrafluoroethylene and vinylidene fluoride.

The polymer, preferably one kind or two or more kinds of polymers, in the structural units constituting the one kind or two or more kinds of polymers, may include: a first structural unit; and, a second structural unit selected from the group consisting of The group consisting of hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate and methyl methacrylate. That is, the first structural unit and the second structural unit may be included in one kind of polymer to constitute a copolymer, or may be separately contained in different polymers to constitute the first polymer having the first structural unit and have At least two kinds of polymers of the second polymer of the second structural unit.

Specifically, the polymer may be polytetrafluoroethylene, polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, and the like.

The content of the polymer is preferably 3% by mass or more based on the total amount of the electrolyte layer. The content of the polymer is preferably 50% by mass or less, and more preferably 40% by mass or less based on the total amount of the electrolyte layer. The content of the polymer is preferably 3 to 50% by mass, and more preferably 3 to 40% by mass based on the total amount of the electrolyte layer.

The polymer has excellent affinity with the ionic liquid contained in the electrolyte layer 42 and therefore can appropriately hold the ionic liquid. As a result, the electrolyte salt in the ionic liquid can also be held. With this, leakage of the ionic liquid when a load is applied to the electrolyte layer 42 can be suppressed.

The oxide particles are, for example, particles of inorganic oxide. The inorganic oxide, for example, may be an inorganic oxide containing Li, Mg, Al, Si, Ca, Ti, Zr, La, Na, K, Ba, Sr, V, Nb, B, Ge, etc. as constituent elements . The oxide particles are preferably at least 1 selected from the group consisting of SiO ₂ , Al ₂ O ₃ , AlOOH, MgO, CaO, ZrO ₂ , TiO ₂ , Li ₇ La ₃ Zr ₂ O ₁₂ , and BaTiO ₃ Kind of particles. Since the oxide particles have polarity, they can promote the dissociation of the electrolyte salt in the electrolyte layer 42 and improve the battery characteristics.

The oxide particles may be oxides of rare earth metals. Specifically, the oxide particles may be scandium oxide, yttrium oxide, lanthanum oxide, cerium oxide, gallium oxide, rubidium oxide, samarium oxide, europium oxide, yttrium oxide, yttrium oxide, dysprosium oxide, yttrium oxide, erbium oxide, oxide Qin, ytterbium oxide, ytterbium oxide, etc.

From the viewpoint of excellent discharge characteristics of the secondary battery, the specific surface area of the oxide particles is preferably 5 m ² /g or more, 10 m ² /g or more, or 15 m ² /g, preferably 100 m ² /g or less, 80m ² /g or less, or 60m ² /g or less. The specific surface area of the oxide particles means the specific surface area of the entire oxide particles including the primary particles and the secondary particles, and is measured according to the BET method.

The average particle diameter of the oxide particles is preferably 0.005 μm or more, more preferably 0.01 μm or more, and still more preferably 0.03 μm or more. The average particle diameter of the oxide particles is preferably 5 μm or less, more preferably 3 μm or less, and still more preferably 1 μm or less. The average particle diameter of the oxide particles is measured according to the laser diffraction method, and corresponds to the particle diameter at which the volume accumulation reaches 50% when the volume cumulative particle size distribution curve is drawn from the small particle diameter side.

Based on the total amount of the electrolyte layer, the content of oxide particles is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and particularly preferably 20% by mass or more, and, It is preferably 60% by mass or less, more preferably 50% by mass or less, and still more preferably 40% by mass or less.

The electrolyte salt may be at least one selected from the group consisting of lithium salt, sodium salt, calcium salt and magnesium salt. The electrolyte salt may be the same as the electrolyte salt that can be used in the positive electrode mixture layer 45 and the negative electrode mixture layer 47.

The ionic liquid may be the ionic liquid described above as the ionic liquid contained in the positive electrode mixture layer 45. In ionic liquids, electrolyte salts are soluble. From the viewpoint of further improving charge-discharge characteristics, the concentration of the electrolyte salt per unit volume of the ionic liquid is preferably 0.5 mol/L or more, more preferably 0.7 mol/L or more, and still more preferably 0.8 mol/L or more And, it is preferably 2.0 mol/L or less, more preferably 1.8 mol/L or less, and still more preferably 1.5 mol/L or less.

From the viewpoint of making the electrolyte layer 42 appropriately, the content of the ionic liquid may be 10% by mass or more or 80% by mass based on the total amount of the electrolyte layer as a reference. From the viewpoint of further improving the conductivity and suppressing the decrease in the capacity of the secondary battery, the total content of the electrolyte salt and the ionic liquid is preferably 10% by mass or more, more preferably 25% by mass based on the total amount of electrolyte layers as a reference Above, further preferably 40% by mass or more. From the viewpoint of suppressing the decrease in the strength of the electrolyte layer, the total content of the electrolyte salt and the ionic liquid is preferably 80% by mass or less based on the total amount of the electrolyte layer as a reference.

From the viewpoint of improving strength and improving safety, the thickness of the electrolyte layer 42 is preferably 5 μm or more, and more preferably 10 μm or more. From the viewpoint of further reducing the internal resistance of the secondary battery and the viewpoint of further improving the large current characteristics, the thickness of the electrolyte layer 42 is preferably 200 μm or less, more preferably 150 μm or less, and still more preferably 100 μm or less.

The secondary battery 1 described above uses the screw 9 and the nut 10 to fasten the substrates (8, 8) to each other, so that the sandwiching member 3 sandwiches the laminated battery 2. With this, the positive electrode 41, the electrolyte layer 42 and the negative electrode 43 in the laminated battery 2 become a pressurized state in which pressure is applied in the stacking direction D1, and the holding member 3 serves as a holding means for holding the pressurized state Function.

As long as a pressure of 0.1 MPa or more is applied to the positive electrode 41, the electrolyte layer 42 and the negative electrode 43, from the viewpoint of further improving the initial characteristics, it is preferable to apply a pressure of 0.2 MPa or more, 0.4 MPa or more, or 0.5 MPa or more, More preferably, a pressure of 0.7 MPa or more, 0.8 MPa or more, 0.9 MPa or more, or 1.0 MPa or more is applied.

In this secondary battery 1, the pressing state of the positive electrode 41, the electrolyte layer 42 and the negative electrode 43 is held by the holding member 3 (holding means), so it is considered that the positive electrode 41 (positive electrode mixture layer 45) and the electrolyte can be formed well The interface between the layer 42 and the interface between the negative electrode 43 (negative electrode mixture layer 47) and the electrolyte layer 42 (the adhesion of the interface is improved), as a result, a secondary battery 1 (laminated battery 2) having excellent initial characteristics can be obtained.

In the above embodiment, in the secondary battery 1 provided with the laminated secondary battery 2, the holding member 3 functions as a holding means, and as the holding means of another embodiment, for example, a thermoplastic resin can be used , Thermosetting resin, photocurable resin and other resin materials. Specifically, the pressurized state of the positive electrode 41, the electrolyte layer 42 and the negative electrode 43 can be maintained by disposing and curing the resin material at the ends of the positive electrode 41, the electrolyte layer 42 and the negative electrode 43. Alternatively, the pressurized state of the positive electrode 41, the electrolyte layer 42 and the negative electrode 43 may be maintained by arranging and curing the resin material so as to cover the entire laminated battery 2, for example.

In another embodiment, batteries other than laminated batteries can be used. FIG. 3 is a perspective view showing the overall structure and internal structure of a secondary battery according to another embodiment. As shown in FIG. 3, the secondary battery 11 is a wound type (18650 type, also known as a cylindrical type) secondary battery, which includes: an electrode group 14; and a battery container 15 for accommodating electrodes The group 14 is cylindrical and has an opening on the top surface; and, the cover 16 is used to close the opening of the battery container 15.

The electrode group 14 includes an elongated positive electrode 41, an electrolyte layer 42 and a negative electrode 43 in this order. The entire outer peripheral surface of the electrode group 14 is provided with an insulating coating, which is not shown. The battery container 15 may be, for example, a steel container to which nickel plating has been applied. The cover 16 is, for example, crimped and fixed to the upper portion of the battery container 15 via an insulating resin gasket.

The positive electrode 41 and the negative electrode 43 are provided with a positive electrode collector terminal and a negative electrode collector terminal (not shown) so that each of the positive electrode 41 and the negative electrode 43 can be electrically connected to the outside of the secondary battery 11. One end of the positive electrode collector terminal is welded to the lower surface of the lid 16 of the secondary battery 11 by ultrasonic welding, for example. One end of the negative electrode collector terminal is joined to the inner bottom portion 15a of the battery container 15 by resistance welding, for example. In one embodiment, the positive electrode current collector terminal is formed of aluminum, and the negative electrode current collector terminal is formed of copper.

FIG. 4( a) is a perspective view showing the electrode group 14 shown in FIG. 3, and FIG. 4( b) is a schematic cross-sectional view showing the main part of the electrode group 14. As shown in FIG. 4, the electrode group 14 is formed by winding a long laminate 17 into a spiral shape. The laminate 17 includes, for example, an electrolyte layer 42, a positive electrode 41, an electrolyte layer 42 and a negative electrode 43 in order from the inside of the spiral shape. A fixing member 13 is provided on the outermost surface of the electrode group 14, and this fixing member 13 fixes the front end portion of the laminate 17 to the laminate 17 located directly below it. The fixing member 13 may be a member that can be attached, such as an adhesive tape, or may be a member obtained by curing a resin material such as a thermoplastic resin, a thermosetting resin, or a photocurable resin.

In this secondary battery 11, for example, when the laminate 17 is wound, by applying a winding tension, the laminate 17 (electrolyte layer 42, positive electrode 41, electrolyte layer 42 and negative electrode) in the obtained electrode group 14 is made 43) It becomes a pressurized state in which pressure is applied in the stacking direction D2. Further, the fixing member 13 functions as a holding means, and by fixing the front end of the laminate 17, the pressed state of the laminate 17 is maintained.

In this secondary battery 11, since the pressurized state of the positive electrode 41, the electrolyte layer 42 and the negative electrode 43 is also held by the fixing member 13 (holding means), it is considered that the positive electrode 41 (positive electrode mixture layer 45) and The interface between the electrolyte layer 42 and the interface between the negative electrode 43 (negative electrode mixture layer 47) and the electrolyte layer 42 (the adhesion of the interface is improved), as a result, a secondary battery (wound battery) 11 having excellent initial characteristics can be obtained.

Next, the method of manufacturing the secondary battery will be described. A manufacturing method according to an embodiment includes: a pressurizing step that applies pressure to a laminate in a stacking direction, the laminate having a positive electrode 41, an electrolyte layer 42 and a negative electrode 43 in sequence; and, a holding step provided with holding means, The holding means is used to maintain the pressurized state of the laminate to which the pressure is applied.

In the pressurization step, first, a laminate is prepared. When the secondary battery is a laminated battery, a laminate can be produced, for example, by providing an electrolyte layer 42 between the positive electrode 41 and the negative electrode 43, the positive electrode 41 forming a positive electrode mixture on the positive electrode current collector 44 The negative electrode 43 is obtained by forming the negative electrode mixture layer 47 on the negative electrode current collector 46. When the secondary battery is a wound battery, the layered body can be produced by, for example, a method in which the positive electrode 41 in the first layered body and the electrolyte layer 42 in the second layered body are in contact with each other to further layer 1 laminated body and second laminated body, the first laminated body is obtained by laminating the electrolyte layer 42 on the positive electrode 41 obtained in the same manner as above, the second laminated body is carried out in the same manner as above The obtained negative electrode 43 is obtained by laminating an electrolyte layer 42.

Specifically, the positive electrode mixture layer 45 can be obtained by, for example, applying a slurry-like positive electrode mixture to one surface of the positive electrode current collector 44 and then volatilizing the dispersion medium. The material used in the positive electrode mixture layer 45 is dispersed in the dispersion medium (the negative electrode mixture layer 47 is also the same). The dispersion medium may be, for example, an organic solvent such as N-methyl-2-pyrrolidone.

In one embodiment, the electrolyte layer 42 is an electrolyte layer formed in a sheet shape in advance, and then is provided on the positive electrode 41, the negative electrode 43, or between the positive electrode 41 and the negative electrode 43. Specifically, first, after applying the electrolyte slurry on the base material, the dispersion medium is volatilized, thereby obtaining a sheet-shaped electrolyte layer in which the above-mentioned material used in the electrolyte layer is dispersed in the dispersion medium In the middle. The dispersion medium may be, for example, water, N-methyl-2-pyrrolidone (NMP), toluene, or the like. The electrolyte layer 42 can be provided on the positive electrode 41, the negative electrode 43, or the positive electrode 41 and the negative electrode by pressing in a state where the electrolyte layer is overlapped in contact with the positive electrode mixture layer 45 and/or the negative electrode mixture layer 47 Between 43.

In another embodiment, the electrolyte layer 42 can be obtained by coating and drying an electrolyte slurry on the positive electrode mixture layer 45 and/or the negative electrode mixture layer 47. The material in the electrolyte layer is dispersed in the dispersion medium.

The content of the polymer in the electrolyte slurry may be 3% by mass or more based on the total amount of non-volatile components in the electrolyte slurry (components from which the dispersion medium is excluded from the electrolyte slurry), and may also be 50% by mass or less or 40% by mass or less.

The content of oxide particles in the electrolyte slurry may be 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more based on the total amount of non-volatile components in the electrolyte slurry. It may be 60% by mass or less, 50% by mass or less, or 40% by mass or less.

The total amount of the content of the ionic liquid and the electrolyte salt in the electrolyte slurry may be 90% by mass or less, 85% by mass or less, or 80% by mass based on the total amount of nonvolatile components in the electrolyte slurry.

The content of the dispersion medium in the electrolyte slurry may be, for example, 5 parts by mass or more, or 1000 parts by mass or less with respect to 100 parts by mass of nonvolatile components in the electrolyte slurry.

Then, in the pressurizing step, pressure is applied in the stacking direction of the laminate. For example, in the secondary battery 1 shown in FIGS. 1 and 2, the substrates (8, 8) are fastened to each other by the screw 9 and the nut 10, thereby sandwiching the laminated battery with the clamping member 3 2, and apply pressure to the laminate (positive electrode 41, electrolyte layer 42, and negative electrode 43) in the stacking direction D1. For example, in the secondary battery 11 shown in FIGS. 3 and 4, when the layered body 17 is wound into a spiral shape, by applying a winding tension, the layered body 17 (electrolyte layer) is stacked in the layering direction D2. 42. The positive electrode 41, the electrolyte layer 42 and the negative electrode 43) apply pressure.

The pressure in the pressurization step may be, for example, 0.1 MPa or more. From the viewpoint of further improving the initial characteristics of the secondary battery, it is preferably 0.2 MPa or more, 0.4 MPa or more, or 0.5 MPa or more, and more preferably 0.7 MPa or more , 0.8MPa or more, 0.9MPa or more, or 1.0MPa or more.

The holding step following the pressing step is to provide holding means for holding the pressure applied in the pressing step. For example, in the secondary battery 1 shown in FIGS. 1 and 2, the predetermined pressure is applied to the laminate (positive electrode 41, electrolyte layer 42, and negative electrode 43 ), and the screw 9 and the nut 10 are used to fasten The substrates (8, 8) are tightly held against each other, and this state is maintained, thereby maintaining the pressurized state of the laminate. That is, when the secondary battery 1 shown in FIGS. 1 and 2 is manufactured, the pressurizing step and the holding step are performed almost continuously (nearly simultaneously). In the secondary battery 11 shown in FIGS. 3 and 4, when a predetermined pressure is applied to the laminated body 17, the front end of the laminated body 17 is fixed by the fixing member 13, thereby maintaining the Pressure state.

In one embodiment, from the viewpoint of further improving the initial characteristics of the secondary battery, the manufacturing method of the secondary battery preferably further includes a step of heating the laminate after the holding step. In the heating step, it is considered that by heating while maintaining the pressurized state of the laminate, the interface between the positive electrode 41 (positive electrode mixture layer 45) and the electrolyte layer 42 and the negative electrode 43 (negative electrode mixture layer 47) and The interface of the electrolyte layer 42 (adhesion of the interface is further improved).

From the viewpoint of improving the discharge characteristics of the secondary battery, the heating temperature in the heating step is preferably 25°C or higher, more preferably 40°C or higher, even more preferably 50°C or higher, and particularly preferably 60°C or higher. The heating temperature in the heating step may be, for example, 100°C or lower. From the viewpoint of improving the discharge characteristics of the secondary battery, it is preferably 90°C or lower, and more preferably 80°C or lower. [Example]

Hereinafter, the present invention will be described more specifically with examples, but the present invention is not limited to these examples.

[Example 1] <Preparation of positive electrode> 79.6 parts by mass of layered lithium/nickel/manganese/cobalt composite oxide (positive electrode active material) and 3.87 parts by mass of acetylene black (conductive material, average particle diameter 48 nm, ratio Surface area is 39m ² /g, manufactured by Denka Co., Ltd., trade name: HS-100), 0.43 parts by mass of acetylene black (conductive material, average particle diameter is 23nm, specific surface area is 133m ² /g, manufactured by Denka Co., Ltd. ), 2.1 parts by mass of a copolymer of vinylidene fluoride and hexafluoropropylene (a binder), and 14 parts by mass of a lithium salt dissolved in 1 mol/L (lithium bis(fluoromethanesulfonyl)imide (LiFSI)) The ionic liquid (bis(fluorosulfonyl)imide N-methyl-N-propylpyrrolidinium (Py13-FSI)). Next, a dispersion medium, N-methyl-2-pyrrolidone (NMP), was added and kneaded, thereby preparing a slurry-like positive electrode mixture. This positive electrode mixture was applied to a positive electrode current collector (aluminum foil with a thickness of 20 μm) at a coating amount of 135 g/m ² , and heated at 80° C. to volatilize the dispersion medium. Then, compaction was performed by pressing until the mixture density was 3.00 g/cm ³ to form a positive electrode mixture layer (thickness 52 μm). The obtained laminate was die-cut into a square of 3.0 cm×4.5 cm to prepare a positive electrode.

<Preparation of negative electrode> Mix 76.9 parts by mass of graphite (negative electrode active material, manufactured by Hitachi Chemical Co., Ltd.) and 0.49 parts by mass of carbon fiber (conductive material, average fiber diameter is 150 nm, trade name: VGCF-H, Showa Denko Co., Ltd. (Manufactured), 4.11 parts by mass of a copolymer of vinylidene fluoride and hexafluoropropylene (binder), and 18.5 parts by mass of an ionic liquid (Py13-FSI) in which a 1 mol/L lithium salt (LiFSI) is dissolved. Then, the dispersion medium, that is, NMP is added and kneaded, thereby preparing a slurry-like negative electrode mixture. This negative electrode mixture was coated on the negative electrode current collector (copper foil with a thickness of 10 μm) at a coating amount of 73 g/m ² , and heated at 80° C. to volatilize the dispersion medium. Then, compaction was performed by pressing until the mixture density was 1.90 g/cm ³ to form a negative electrode mixture layer (thickness: 38 μm). The obtained laminate was die-cut into a square of 3.1 cm×4.6 cm to prepare a negative electrode.

<Preparation of electrolyte layer> 40 parts by mass of SiO ₂ particles (average particle diameter of 0.04 μm, specific surface area of 50 m ² /g) and 60 parts by mass of copolymer of vinylidene fluoride and hexafluoropropylene are added, and then dispersed The medium is NMP and kneaded to obtain a mixture of SiO ₂ particles and copolymer. Furthermore, LiFSI (electrolyte salt) dried in a dry argon atmosphere was dissolved in Py13-FSI (ionic liquid) at a concentration of 1.5 mol/L. Then, a mixture of SiO ₂ particles and copolymer and an ionic liquid in which electrolyte salts are dissolved are mixed to prepare an electrolyte slurry. In this case, SiO ₂ particles and the volume ratio of ionic liquid dissolved electrolyte salt, the SiO ₂ particle is: dissolved salt of an ionic liquid electrolyte = 20: 80 The obtained slurry was coated on a base material (thickness: 40 μm) made of polyethylene terephthalate, and heated to volatilize the dispersion medium, thereby obtaining an electrolyte layer (electrolyte sheet). The thickness of the obtained electrolyte layer is 20±5 μm.

<Making a laminated battery> A layered body is produced by laminating the positive electrode, the electrolyte layer, and the negative electrode prepared in this order in this order. This laminate was placed in an aluminum laminate container (product name: aluminum laminate film, manufactured by Dai Nippon Printing Co., Ltd.), and the laminate container was vacuum-sucked and then thermally welded to prepare an evaluation. Used laminated battery.

<Apply pressure to laminated battery> The sandwich type battery (made of stainless steel (SUS)) shown in Fig. 1 was used to sandwich the laminated battery produced above, and a pressure of 0.14 MPa was applied in the stacking direction of the laminate at 25°C. Tighten it with a nut to obtain a secondary battery that remains under pressure. At this time, in order to prevent the secondary battery from being short-circuited, the collector terminal does not directly contact the clamping member. Furthermore, a spring is arranged between the substrate of the clamping member and the nut so that the pressure can be adjusted.

<Examples 2-9> Except having changed the pressure at the time of pressure application to the pressure shown in Table 1, it carried out similarly to Example 1, and produced the secondary battery.

<Examples 10 to 13> The laminated battery was held by the holding member, and the pressurized state was maintained. In this state, the secondary battery was heated at the temperature shown in Table 1 for 30 minutes. Except for this, it was carried out in the same manner as in Example 5. To make secondary batteries.

<Comparative Example 1> Except that no pressure was applied to the laminate, it was carried out in the same manner as in Example 1 to produce a secondary battery.

<Early evaluation characteristics> For each of the secondary batteries of the examples and comparative examples, a charge and discharge device (trade name: BATTERY TEST UNIT, manufactured by IEM Co., Ltd.) was used at 25° C. with a current value of 0.1 C and a charge termination voltage of 4.2 V. Implement constant current charging. After stopping for 15 minutes, constant current discharge was performed under the conditions of a current value of 0.1 C and a discharge end voltage of 2.7 V. The charge and discharge were repeated 3 times under the above charge and discharge conditions, and the discharge capacity (initial capacity) at the third time was measured. The initial characteristics of the lithium ion secondary battery are calculated according to the following formula. Initial characteristics (%) = (initial capacity/design capacity) ×100 The results are shown in Table 1. Furthermore, the evaluation is carried out according to the following criteria. A: Initial characteristics are above 95% B: The initial characteristics are more than 80% but less than 95% C: Initial characteristics are more than 70% but less than 80% D: Initial characteristics are less than 70%

[Table 1]

<Evaluate discharge characteristics> For the secondary batteries of Example 5 and Examples 10 to 13, a charge and discharge device (trade name: BATTERY TEST UNIT, manufactured by IEM Co., Ltd.) was used, and the discharge capacity at 25° C. was measured under the following charge and discharge conditions. (1) Perform the following cycle once to obtain the discharge capacity: after the constant voltage and constant voltage (CCCV) charging is performed under the condition that the termination voltage is 4.2V and 0.1C, the constant current (CC) discharge is performed at 0.1C to the end The voltage is up to 2.7V. Furthermore, C means "current value (A)/battery capacity (Ah)". (2) Then, perform the following cycle once to obtain the discharge capacity: after the constant voltage and constant voltage (CCCV) charge is performed under the condition that the termination voltage is 4.2V and 0.1C, the constant current (CC) discharge is performed at 0.5C Until the end voltage is 2.7V. From the obtained discharge capacity, the following formula was used to calculate the discharge characteristics. Discharge characteristics = discharge capacity obtained in (2) / discharge capacity obtained in (1) The results are shown in Table 2. Furthermore, the evaluation is carried out according to the following criteria. A: The discharge characteristic is 0.9 or more. B: The discharge characteristic is 0.8 or more but less than 0.9. C: The discharge characteristic is less than 0.8.

[Table 2]

1, 11‧‧‧ secondary battery 2‧‧‧Laminated battery 3‧‧‧ means of keeping 4, 14‧‧‧ electrode group 5‧‧‧Battery shell 6‧‧‧Positive collector terminal 7‧‧‧Negative collector terminal 8‧‧‧ substrate 8a‧‧‧hole 9‧‧‧screw 10‧‧‧Nut 13‧‧‧ Holding means (fixed member) 15‧‧‧Battery container 15a‧‧‧Inner bottom 16‧‧‧ cover 17‧‧‧Layered body 41‧‧‧Positive 42‧‧‧Electrolyte layer 43‧‧‧Negative 44‧‧‧Positive collector 45‧‧‧positive mixture layer 46‧‧‧Negative collector 47‧‧‧Negative mixture layer D1, D2‧‧‧Stacking direction

Fig. 1 is an exploded perspective view showing a secondary battery according to an embodiment. Fig. 2 is a schematic cross-sectional view showing a secondary battery according to an embodiment. FIG. 3 is a perspective view showing the overall structure and internal structure of a secondary battery according to another embodiment. FIG. 4(a) is a perspective view showing an electrode group according to an embodiment, and FIG. 4(b) is a schematic cross-sectional view showing a main part of the electrode group.

Domestic storage information (please note in order of storage institution, date, number) no

Overseas hosting information (please note in order of hosting country, institution, date, number) no

1‧‧‧Secondary battery

2‧‧‧Laminated battery

3‧‧‧ Holding means (clamping member)

4‧‧‧electrode group

5‧‧‧Battery shell

6‧‧‧Positive collector terminal

7‧‧‧Negative collector terminal

8‧‧‧ substrate

8a‧‧‧hole

9‧‧‧screw

10‧‧‧Nut

Claims (11)

A secondary battery including a positive electrode, an electrolyte layer, and a negative electrode, wherein, The positive electrode, the electrolyte layer, and the negative electrode are stacked in this order, and are in a pressurized state where pressure is applied in the stacking direction, In addition, the secondary battery further includes holding means for holding the pressurized state. The secondary battery according to claim 1, wherein the positive electrode, the electrolyte layer, and the negative electrode are applied with a pressure of 0.7 MPa or more in the stacking direction. The secondary battery according to claim 1 or 2, wherein the electrolyte layer contains a polymer, oxide particles, electrolyte salt, and ionic liquid. The secondary battery according to any one of claims 1 to 3, wherein the positive electrode includes a positive electrode current collector and a positive electrode mixture layer, the positive electrode mixture layer is provided on the positive electrode current collector, and the positive electrode mixture layer contains Positive active material and ionic liquid. The secondary battery according to any one of claims 1 to 4, wherein the negative electrode includes a negative electrode current collector and a negative electrode mixture layer, the negative electrode mixture layer is provided on the negative electrode current collector, and the negative electrode mixture layer contains Negative active material and ionic liquid. A method for manufacturing a secondary battery, including: A pressurizing step, which applies pressure to the layered body in the direction of the layering, the layered body is sequentially provided with a positive electrode, an electrolyte layer, and a negative electrode; and, In the holding step, it is provided with holding means for holding the pressurized state of the aforementioned laminated body to which pressure is applied. The method for manufacturing a secondary battery according to claim 6, wherein in the pressurizing step, pressure is applied to the laminate at 0.7 MPa or more in the lamination direction. The method for manufacturing a secondary battery according to claim 6 or 7, further comprising a heating step after the holding step, the heating step heating the laminate at 50°C or higher. The method for manufacturing a secondary battery according to any one of claims 6 to 8, wherein the electrolyte layer contains a polymer, oxide particles, electrolyte salt, and ionic solution. The method for manufacturing a secondary battery according to any one of claims 6 to 9, wherein the positive electrode includes a positive electrode current collector and a positive electrode mixture layer, the positive electrode mixture layer is provided on the positive electrode current collector, and the positive electrode The mixture layer contains a positive electrode active material and an ionic liquid. The method for manufacturing a secondary battery according to any one of claims 6 to 10, wherein the negative electrode includes a negative electrode current collector and a negative electrode mixture layer, the negative electrode mixture layer is provided on the negative electrode current collector, and the negative electrode The mixture layer contains the negative electrode active material and the ionic liquid.

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