JP2020170673A - Battery members for secondary battery and secondary battery - Google Patents

Abstract

To provide battery members for a secondary battery capable of manufacturing a secondary battery having excellent safety.SOLUTION: A battery member 13, 14 for a secondary battery according to an embodiment of the present invention includes a current collector 9, 11, an electrode mixture layer 10, 12 provided on the current collector 9, 11, and an electrolyte layer 7 provided on the electrode mixture layer 10, 12, and the electrode mixture layer 10, 12 includes an electrode active material, an electrolyte salt, and a non-aqueous solvent, and the electrolyte layer 7 includes an ion conductive polymer. The battery member 13, 14 for the secondary battery according to another embodiment of the present invention includes a current collector 9, 11, an electrode mixture layer 10, 12 provided on the current collector 9, 11, and an electrolyte layer 7 provided on the electrode mixture layer 10, 12, and the electrode mixture layer 10, 12 includes an electrode active material, an electrolyte salt, and an ionic liquid, and the electrolyte layer 7 includes an ionic conductive polymer.SELECTED DRAWING: Figure 3

Description

The present invention relates to a battery member for a secondary battery and a secondary battery.

In recent years, the penetration rate of electric vehicles and hybrid vehicles, which have a small environmental load, has been increasing. These automobiles are equipped with secondary batteries such as nickel-metal hydride batteries and lithium-ion secondary batteries. Secondary batteries for automobiles are required to have high safety as well as battery characteristics. As a method for improving the safety of the secondary battery, a method of changing the electrolytic solution to a solid electrolyte is known (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2004-107641

However, the safety of the conventional secondary battery is still insufficient, and there is room for further improvement.

Therefore, a main object of the present invention is to provide a battery member for a secondary battery capable of producing a secondary battery having excellent safety.

One aspect of the present invention includes a current collector, an electrode mixture layer provided on the current collector, and an electrolyte layer provided on the electrode mixture layer, and the electrode mixture layer has electrode activity. A battery member for a secondary battery, which contains a substance, an electrolyte salt, and a non-aqueous solvent, and the electrolyte layer contains an ionic conductive polymer.

In the electrolyte layer of this battery member, since ionic conductivity is ensured by using an ionic conductive polymer, it is not necessary to use an electrolytic solution (non-aqueous solvent). By providing such an electrolyte layer on the electrode mixture layer, leakage of a non-aqueous solvent contained in the electrode mixture layer can be suppressed. Therefore, according to this battery member, it is possible to manufacture a secondary battery having excellent safety.

The electrode mixture layer may further contain a polymer capable of gelling a non-aqueous solvent. In this case, since the non-aqueous solvent is gelled, leakage of the non-aqueous solvent is further suppressed, and a secondary battery can be manufactured even more excellent in terms of safety.

The electrode mixture layer may further contain an ionic liquid. In this case, in the electrode mixture layer, the electrolyte salt dissolves in the ionic liquid so that it easily comes into contact with the electrode active material, so that the battery characteristics can be improved.

Another aspect of the present invention includes a current collector, an electrode mixture layer provided on the current collector, and an electrolyte layer provided on the electrode mixture layer, and the electrode mixture layer comprises. It is a battery member for a secondary battery containing an electrode active material, an electrolyte salt, and an ionic liquid, and the electrolyte layer contains an ionic conductive polymer.

By using the ionic liquid in the electrode mixture layer of the battery member, the electrolyte salt is dissolved in the ionic liquid and easily comes into contact with the electrode active material. Further, in the electrolyte layer, ionic conductivity is ensured by using an ionic conductive polymer. Therefore, it is not necessary to use an electrolytic solution (non-aqueous solvent) in either the electrode mixture layer or the electrolyte layer. Therefore, according to this battery member, it is possible to manufacture a secondary battery having excellent safety.

Another aspect of the present invention is a secondary battery including the above battery member.

According to one aspect of the present invention, there is provided a battery member for a secondary battery capable of producing a secondary battery having excellent safety. Further, according to another aspect of the present invention, a secondary battery having excellent safety is provided.

It is a perspective view which shows the secondary battery which concerns on 1st Embodiment. It is an exploded perspective view which shows the electrode group of the secondary battery shown in FIG. (A) is a schematic cross-sectional view showing a secondary battery battery member (positive electrode member) according to one embodiment, and (b) is a schematic showing a secondary battery battery member (negative electrode member) according to another embodiment. It is a sectional view. It is an exploded perspective view which shows the electrode group of the secondary battery which concerns on 2nd Embodiment. It is a schematic cross-sectional view which shows the battery member (bipolar electrode member) for a secondary battery which concerns on another embodiment.

Hereinafter, embodiments 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 components (including steps and the like) are not essential unless otherwise specified. The sizes of the components in each figure are conceptual, and the relative size relationships between the components are not limited to those shown in each figure.

The numerical values and their ranges in the present specification do not limit the present invention. The numerical range indicated by using "~" in the present specification indicates a range including the numerical values before and after "~" as the minimum value and the maximum value, respectively. In the numerical range described stepwise in the present 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 another stepwise description. Further, in the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[First Embodiment]
FIG. 1 is a perspective view showing a secondary battery according to the first embodiment. As shown in FIG. 1, the secondary battery 1 includes an electrode group 2 composed of a positive electrode, a negative electrode, and an electrolyte layer, and a bag-shaped battery exterior body 3 accommodating the electrode group 2. The positive electrode and the negative electrode are provided with a positive electrode current collecting tab 4 and a negative electrode current collecting tab 5, respectively. The positive electrode current collecting tab 4 and the negative electrode current collecting tab 5 project from the inside of the battery exterior 3 to the outside so that the positive electrode and the negative electrode can be electrically connected to the outside of the secondary battery 1, respectively.

The battery exterior 3 may be formed of, for example, a laminated film. The laminated film may be, for example, a laminated film in which a resin film such as polyethylene terephthalate (PET) film, a metal foil such as aluminum, copper, and stainless steel, and a sealant layer such as polypropylene are laminated in this order.

FIG. 2 is an exploded perspective view showing the electrode group 2 of the secondary battery shown in FIG. As shown in FIG. 2, the electrode group 2A according to the embodiment includes a positive electrode 6, an electrolyte layer 7, and a negative electrode 8 in this order. The positive electrode 6 includes a first current collector 9 and a positive electrode mixture layer 10 provided on the first current collector 9. A positive electrode current collector tab 4 is provided on the first current collector 9 of the positive electrode 6. The negative electrode 8 includes a second current collector 11 and a negative electrode mixture layer 12 provided on the second current collector 11. A negative electrode current collector tab 5 is provided on the second current collector 11 of the negative electrode 8. In the present specification, the positive electrode mixture layer 10 and the negative electrode mixture layer 12 are collectively referred to as an electrode mixture layer. Similarly, the positive electrode active material and the negative electrode active material described later are collectively referred to as an electrode active material.

In one embodiment, the electrode group 2A includes a first battery member (positive electrode member) including a first current collector 9, a positive electrode mixture layer 10, and an electrolyte layer 7 in this order. You can see it. FIG. 3A is a schematic cross-sectional view showing a battery member (positive electrode member) for a secondary battery according to an embodiment, that is, a schematic cross-sectional view showing a first battery member (positive electrode member). As shown in FIG. 3A, the first battery member 13 includes a first current collector 9, a positive electrode mixture layer 10 provided on the first current collector 9, and a positive electrode mixture layer. It is a positive electrode member including an electrolyte layer 7 provided on the 10 in this order.

The first current collector 9 may be made of a metal such as aluminum, titanium, tantalum, or an alloy thereof. The first current collector 9 is preferably made of aluminum or an alloy thereof because it is lightweight and has a high weight energy density.

In one embodiment, the positive electrode mixture layer 10 contains a positive electrode active material, an electrolyte salt, and a non-aqueous solvent.

The positive electrode active material may be a lithium transition metal compound such as a lithium transition metal oxide or a lithium transition metal phosphate.

The lithium transition metal oxide may be, for example, lithium manganate, lithium nickel oxide, lithium cobalt oxide, or the like. The lithium transition metal oxide is a part of transition metals such as Mn, Ni, and Co contained in lithium manganate, lithium nickelate, lithium cobalt, etc., and one or more other transition metals, or It may be a lithium transition metal oxide substituted with a metal element (typical element) such as Mg or Al. That is, the lithium transition metal oxide may be a compound represented by ^LiM 1 _{O 2} or ^{LiM ₁} 2 _O 4 ^(M ₁ comprises at least one transition metal). Specifically, the lithium transition metal oxides are Li (Co _1/3 Ni _1/3 Mn _1/3 ) O ₂ , LiNi _1/2 Mn _1/2 O ₂ , and LiNi _1/2 Mn _3/2 O. It may be ₄ mag.

The lithium transition metal oxide is preferably a compound represented by the following formula (1) from the viewpoint of further improving the energy density.
Li _a Ni _b Co _c M ² _d O _{2 + e} (1)
[In the formula (1), M ² is at least one selected from the group consisting of Al, Mn, Mg and Ca, and a, b, c, d and e are 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 phosphates are LiFePO ₄ , LiMnPO ₄ , LiMn _x M ³ _1-x PO ₄ (0.3 ≦ x ≦ 1, M ³ are Fe, Ni, Co, Ti, Cu, Zn, Mg, and It may be at least one element selected from the group consisting of Zr) and the like.

The content of the positive electrode active material may be 70% by mass or more, 80% by mass or more, or 90% by mass or more 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 electrolyte salt may be at least one selected from the group consisting of lithium salt, sodium salt, calcium salt, and magnesium salt.

Anion of the electrolyte salt, a halide ion ^{(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 -, BPh 4 -, B (C 2 H 4 O _{^{2) 2 -, C (FSO}} 2) 3 -, C (CF 3 SO 2) 3 -, CF 3 COO -, CF 3 SO 2 O -, C 6 F 5 SO 2 O -, [B (C 2 O _{4) 2]} ^- it may be like. The anions are preferably PF ₆ ⁻ , BF ₄ ⁻ , N (SO ₂ F) ₂ ⁻ , N (SO ₂ CF ₃ ) ₂ ⁻ , [B (C ₂ O ₄ ) ₂ ] ⁻ , or ClO ₄ ⁻ . is there.

In the following, the following abbreviations may be used.
[FSI] ⁻ : N (SO ₂ F) ₂ ⁻ , bis (fluorosulfonyl) imide anion [TFSI] ⁻ : N (SO ₂ CF ₃ ) ₂ ⁻ , bis (trifluoromethanesulfonyl) imide anion [BOB] ⁻ : [ _{B (C 2 O 4) 2} ] -, bis oxalate borate anion _{^{[f3C] -: C (FSO}} 2) 3 -, tris (fluorosulfonyl) carbanions

Lithium salts include LiPF ₆ , LiBF ₄ , Li [FSI], Li [TFSI], Li [f3C], Li [BOB], LiClO ₄ , LiCF ₃ BF ₃ , LiC ₂ F ₅ BF ₃ , LiC ₃ F ₇ BF. ₃ , LiC ₄ F ₉ BF ₃ , Li [C (SO ₂ CF ₃ ) ₃ ], LiCF ₃ SO ₃ , LiCF ₃ COO, and LiRCOO (R is an alkyl group, phenyl group, or naphthyl having 1 to 4 carbon atoms). It may be at least one selected from the group consisting of groups.).

Sodium salts are NaPF ₆ , NaBF ₄ , Na [FSI], Na [TFSI], Na [f3C], Na [BOB], NaClO ₄ , NaCF ₃ BF ₃ , NaC ₂ F ₅ BF ₃ , NaC ₃ F ₇ BF. ₃ , NaC ₄ F ₉ BF ₃ , Na [C (SO ₂ CF ₃ ) ₃ ], NaCF ₃ SO ₃ , NaCF ₃ COO, and NaRCOO (R is an alkyl group, phenyl group, or naphthyl having 1 to 4 carbon atoms). It may be at least one selected from the group consisting of groups.).

Calcium salts are 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. (CF ₃ BF ₃ ) ₂ , Ca (C ₂ F ₅ BF ₃ ) ₂ , Ca (C ₃ F ₇ BF ₃ ) ₂ , Ca (C ₄ F ₉ BF ₃ ) ₂ , Ca [C (SO ₂ CF ₃ )) ₃ ] ₂ , Ca (CF ₃ SO ₃ ) ₂ , Ca (CF ₃ COO) ₂ , and Ca (RCOO) ₂ (R is an alkyl group, phenyl group, or naphthyl group having 1 to 4 carbon atoms). It may be at least one selected from the group consisting of.

Magnesium salts are Mg (PF ₆ ) ₂ , Mg (BF ₄ ) ₂ , Mg [FSI] ₂ , Mg [TFSI] ₂ , Mg [f3C] ₂ , Mg [BOB] ₂ , Mg (ClO ₄ ) ₂ , Mg. (CF ₃ BF ₃ ) ₂ , Mg (C ₂ F ₅ BF ₃ ) ₂ , Mg (C ₃ F ₇ BF ₃ ) ₂ , Mg (C ₄ F ₉ BF ₃ ) 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, phenyl group, or naphthyl group having 1 to 4 carbon atoms). It may be at least one selected from the group consisting of.

Of these, from the viewpoint of dissociability and electrochemical stability, the electrolyte salt is preferably LiPF ₆ , LiBF ₄ , Li [FSI], Li [TFSI], Li [f3C], Li [BOB], LiClO ₄ , LiCF ₃ BF ₃ , LiC ₂ F ₅ BF ₃ , LiC ₃ F ₇ BF ₃ , LiC ₄ F ₉ BF ₃ , Li [C (SO ₂ CF ₃ ) ₃ ], LiCF ₃ SO ₃ , LiCF ₃ COO, and LiRCO (R is at least one selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, a phenyl group, or a naphthyl group), and more preferably Li [TFSI], Li [FSI], LiPF _6. , LiBF ₄ , Li [BOB], and LiClO _4, at least one selected from the group, more preferably Li [TFSI] or Li [FSI].

The content of the electrolyte salt may be 0.1% by mass or more, 0.4% by mass or more, or 0.7% by mass or more based on the total amount of the positive electrode mixture layer, and is 4.8% by mass or less, 3 It may be 2% by mass or less, or 1.6% by mass or less.

The non-aqueous solvent may be, for example, a carbonate (carbonic acid ester) such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, chloroethylene carbonate, chloropropylene carbonate and the like. The non-aqueous solvent may be a non-aqueous solvent other than carbonate, for example, γ-butyrolactone, 1,2-dimethoxyethane, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide. , Methyl propionate, ethyl propionate, phosphate triester, trimethoxymethane, dioxolane, diethyl ether, sulfolane, 3-methyl-2-oxazolidinone, tetrahydrofuran, 1,2-diethoxyethane and the like. The non-aqueous solvent may be used alone or in combination of two or more.

The content of the non-aqueous solvent may be 1% by mass or more, 3% by mass or more, or 5% by mass or more, based on the total amount of the positive electrode mixture layer, and is 30% by mass or less, 20% by mass or less, or 10% by mass. It may be less than or equal to%.

The positive electrode mixture layer 10 may further contain a polymer capable of gelling a non-aqueous solvent. In the present specification, the polymer capable of gelling a non-aqueous solvent means a polymer capable of significantly reducing the fluidity of the non-aqueous solvent. Specifically, in the following evaluation of fluidity, position A It means a polymer in which the distance between the position B and the position B is less than 1 cm.

First, put a non-aqueous solvent and a non-aqueous solvent in a glass vial (manufactured by AS ONE Corporation, Labran screw tube bottle No. 4, 13.5 mL, bottom diameter: about 2 cm, height: about 4 cm, cylindrical shape). 5 g of a mixture with a gellable polymer (non-aqueous solvent / polymer = 90/10 (mass ratio)) is added and the lid is closed. Subsequently, after melting the polymer at a temperature equal to or higher than the glass transition temperature of the polymer, the polymer is allowed to stand at 25 ° C. for 20 hours with the bottom side of the glass vial bottle facing down and the lid side facing up. Position A is the position of the uppermost surface (the surface farthest from the bottom surface of the glass vial) of the mixture of the non-aqueous solvent and the polymer in the glass vial after standing. Then, the glass vial is allowed to stand at 25 ° C. for 10 minutes in a state where the top and bottom of the glass vial are reversed (the bottom side of the glass vial is up and the lid side is down). The position of the lowermost surface (the surface farthest from the bottom surface of the glass vial) of the mixture of the non-aqueous solvent and the polymer in the glass vial after standing is defined as position B. The fluidity is evaluated based on the distance between the position A and the position B thus obtained.

Polymers capable of gelling non-aqueous solvents include, for example, copolymers of vinylidene fluoride and hexafluoropropylene, polyvinylidene fluoride, polyacrylonitrile, methyl polymethacrylate, methyl polyacrylate, poly (N-isopropylacrylamide), and poly. (Diallyldimethylammonium-bis (trifluoromethanesulfonyl) imide) and the like may be used. The polymer can also be obtained by mixing with a non-aqueous solvent in the state of a monomer or an oligoma and polymerizing. The polymerization can be carried out by heat or light irradiation using a polymerization initiator, if necessary.

The content of the polymer capable of gelling the non-aqueous solvent may be 0.01% by mass or more, 0.1% by mass or more, or 1% by mass or more, based on the total amount of the positive mixture layer, and may be 20% by mass. Hereinafter, it may be 10% by mass or less, or 5% by mass or less.

The positive electrode mixture layer 10 may further contain an ionic liquid. The ionic liquid contains the following anionic and cationic components. The ionic liquid in the present specification is a substance that is liquid at −20 ° C. or higher.

Anion component of the ionic liquid is not particularly ^{limited, Cl -, Br -, I} - halogen anions _{^{such, BF 4 -, N (SO}} 2 F) 2 - or the like of the inorganic _{anion, B} (C _{6 H} 5) _{^{4 -, CH 3 SO 3 -}} , CF 3 SO 3 -, N (C 4 F 9 SO 2) 2 -, N (SO 2 CF 3) 2 -, N (SO 2 CF 2 CF 3) 2 - , etc. It may be an organic anion or the like. Anion component of the ionic liquid, _{^{preferably, B (C 6 H 5)}} 4 -, CH 3 SO 3 -, N (C 4 F 9 SO 2) 2 -, CF 3 SO 3 -, N (SO 2 F) _{^{2 -, N (SO 2 CF}} 3) 2 - and _{N (SO 2 CF 2 CF 3} ) 2 - contains at least one selected from the group consisting of, further improves the ionic conductivity at a relatively low viscosity From the viewpoint of further improving the charge / discharge characteristics, more preferably, N (C ₄ F ₉ SO ₂ ) ₂ ⁻ , CF ₃ SO ₃ ⁻ , N (SO ₂ F) ₂ ⁻ , N (SO ₂ CF ₃ ) ₂ ^It contains at least one selected from the group consisting of ⁻ and N (SO ₂ CF ₂ CF ₃ ) ₂ ^−, and more preferably N (SO ₂ F) ₂ ⁻ .

The cation component of the ionic liquid is not particularly limited, but is preferably at least one selected from the group consisting of a chain quaternary onium cation, a piperidinium cation, a pyroridinium cation, a pyridinium cation, and an imidazolium cation.

［式（２）中、Ｒ^１〜Ｒ^４は、それぞれ独立に、炭素数が１〜２０の鎖状アルキル基、又はＲ−Ｏ−（ＣＨ_２）_ｎ−で表される鎖状アルコキシアルキル基（Ｒはメチル基又はエチル基を表し、ｎは１〜４の整数を表す）を表し、Ｘは、窒素原子又はリン原子を表す。Ｒ^１〜Ｒ^４で表されるアルキル基の炭素数は、好ましくは１〜２０、より好ましくは１〜１０、更に好ましくは１〜５である。］ The chain quaternary onium cation is, for example, a compound represented by the following general formula (2).

[In the formula (2), R ^{1 to} R ⁴ are independently chain alkyl groups having 1 to 20 carbon atoms or chain alkoxyalkyl groups represented by RO-O- (CH ₂ ) _n-. (R represents a methyl group or an ethyl group, n represents an integer of 1 to 4), and X represents a nitrogen atom or a phosphorus atom. The alkyl group represented by R ^{1 to} R ⁴ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms. ]

［式（３）中、Ｒ^５及びＲ^６は、それぞれ独立に、炭素数が１〜２０のアルキル基、又はＲ−Ｏ−（ＣＨ_２）_ｎ−で表されるアルコキシアルキル基（Ｒはメチル基又はエチル基を表し、ｎは１〜４の整数を表す）を表す。Ｒ^５及びＲ^６で表されるアルキル基の炭素数は、好ましくは１〜２０、より好ましくは１〜１０、更に好ましくは１〜５である。］ The piperidinium cation is, for example, a nitrogen-containing six-membered cyclic compound represented by the following general formula (3).

[In the formula (3), R ⁵ and R ⁶ are each independently an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group represented by RO-O- (CH ₂ ) _n- (R is methyl). It represents a group or an ethyl group, and n represents an integer of 1 to 4). The alkyl group represented by R ⁵ and R ⁶ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms. ]

［式（４）中、Ｒ^７及びＲ^８は、それぞれ独立に、炭素数が１〜２０のアルキル基、又はＲ−Ｏ−（ＣＨ_２）_ｎ−で表されるアルコキシアルキル基（Ｒはメチル基又はエチル基を表し、ｎは１〜４の整数を表す）を表す。Ｒ^７及びＲ^８で表されるアルキル基の炭素数は、好ましくは１〜２０、より好ましくは１〜１０、更に好ましくは１〜５である。］ The Helicobacter pyloridinium cation is, for example, a five-membered cyclic compound represented by the following general formula (4).

[In formula (4), R ⁷ and R ⁸ are each independently an alkyl group having 1 to 20 carbon atoms or an alkoxyalkyl group represented by RO-O- (CH ₂ ) _n- (R is methyl). It represents a group or an ethyl group, and n represents an integer of 1 to 4). The alkyl group represented by R ⁷ and R ⁸ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms. ]

［式（５）中、Ｒ^９〜Ｒ^１３は、それぞれ独立に、炭素数が１〜２０のアルキル基、Ｒ−Ｏ−（ＣＨ_２）_ｎ−で表されるアルコキシアルキル基（Ｒはメチル基又はエチル基を表し、ｎは１〜４の整数を表す）、又は水素原子を表す。Ｒ^９〜Ｒ^１３で表されるアルキル基の炭素数は、好ましくは１〜２０、より好ましくは１〜１０、更に好ましくは１〜５である。］ The pyridinium cation is, for example, a compound represented by the following general formula (5).

[In formula (5), R ^{9 to} R ¹³ are independently alkyl groups having 1 to 20 carbon atoms and alkoxyalkyl groups represented by RO-O- (CH ₂ ) _n- (R is a methyl group). Alternatively, it represents an ethyl group, where n represents an integer of 1 to 4), or a hydrogen atom. The alkyl group represented by R ^{9 to} R ¹³ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms. ]

［式（６）中、Ｒ^１４〜Ｒ^１８は、それぞれ独立に、炭素数が１〜２０のアルキル基、Ｒ−Ｏ−（ＣＨ_２）_ｎ−で表されるアルコキシアルキル基（Ｒはメチル基又はエチル基を表し、ｎは１〜４の整数を表す）、又は水素原子を表す。Ｒ^１４〜Ｒ^１８で表されるアルキル基の炭素数は、好ましくは１〜２０、より好ましくは１〜１０、更に好ましくは１〜５である。］ The imidazolium cation is, for example, a compound represented by the following general formula (6).

[In formula (6), R ^{14 to} R ¹⁸ are independently alkyl groups having 1 to 20 carbon atoms and alkoxyalkyl groups represented by RO-O- (CH ₂ ) _n- (R is a methyl group). Alternatively, it represents an ethyl group, where n represents an integer of 1 to 4), or a hydrogen atom. The alkyl group represented by R ^{14 to} R ¹⁸ has preferably 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms. ]

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

In another embodiment, the positive electrode mixture layer 10 contains a positive electrode active material, an electrolyte salt, and an ionic liquid. The types and contents of the positive electrode active material, the electrolyte salt and the ionic liquid may be the same as those in the above-described embodiment.

In each of the above embodiments, the positive electrode mixture layer 10 may further contain a conductive agent, a binder, and the like.

The conductive agent is not particularly limited, but may be a carbon material such as graphite, acetylene black, carbon black, or carbon fiber. The conductive agent may be a mixture of two or more of the above-mentioned carbon materials.

The content of the conductive agent may be 0.1% 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, and is 15% by mass or less, 10% by mass or less, or 8 It may be mass% or less.

The binder is not particularly limited, and contains at least one selected from the group consisting of ethylene tetrafluoride, vinylidene fluoride, hexafluoropropylene, acrylic acid, maleic acid, ethyl methacrylate, and methyl methacrylate as a monomer unit. It may be a rubber such as polymer, styrene-butadiene rubber, isoprene rubber, or acrylic rubber. The binder is preferably a copolyma containing ethylene tetrafluoroethylene and vinylidene fluoride as structural units.

The content of the binder may be 0.1% 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, and is 15% by mass or less, 10% by mass or less, or. It may be 8% by mass or less.

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

The electrolyte layer 7 contains an ionic conductive polymer. The ionic conductive polymer is, for example, a polymer capable of conducting ions derived from an electrolyte salt.

In the present specification, the ionic conductive polymer is a polymer in which a dopant is doped with a base polymer (hereinafter, such a polymer may be referred to as a "base polymer"), and the base polymer and the dopant are used. It can be said that it is a reaction product of. Base polymers usually do not tend to exhibit ionic conductivity, but the dopant is doped and the polymer is oxidized or reduced to form positive and negative charge pairs in the polymer structure, resulting in ions. It is speculated that a conduction path is formed.

The base polymer is not particularly limited as long as it is a polymer that can be oxidized or reduced by a dopant. More specifically, the base polymer is polyphenylene sulfide (PPS), poly (p-phenylene oxide) (PPO), polyether ether ketone (PEEK), polyphthalamide (PPA), polythiophene, polyaniline, polyacetylene, polythiadyl, It may be polydiaacetylene, polypyrrole, polyparaphenylene, polynaphthylene, polyanthracene or the like. The base polymer may be a thermoplastic polymer, preferably polyphenylene sulfide.

The weight average molecular weight of the base polymer is not particularly limited, but is preferably 10,000 to 2 million, more preferably 20,000 to 1.5 million, and even more preferably 30,000 to 1,000,000. The weight average molecular weight means a value converted by a standard polystyrene calibration curve measured by a gel permeation chromatography (GPC) method.

The dopant may be an electron-accepting dopant (acceptor) or an electron-donating dopant (donor). That is, the dopant may be an oxidizing agent or a reducing agent.

Acceptors (oxidizers) include halogens such as bromine, iodine and chlorine, Lewis acids such as BF ₃ , PF ₅ , AsF ₅ , SbF ₅ , HNO ₃ , H ₂ SO ₄ , HClO ₄ , HF, HCl, FSO ₃ Protoacids such as H, CF ₃ SO ₃ H, transition metal halides such as FeCl ₃ , MoCl ₅ , WCl ₅ , SnCl ₄ , MoF ₅ , RuF ₅ , TaBr ₄ , TaBr ₅ , SnI ₄ , 2,3-dichloro Organic compounds such as -5,6-dicyano-p-benzoquinone (DDQ), tetrachloro-1,4-benzoquinone (chloranyl), tetracyanoquinodimethane (TCNQ), tetracyanoethylene (TCNE), oxygen, etc. Be done. These acceptors may be used alone or in admixture of two or more. Doping of the acceptor to the base polymer may be done by electrochemical treatment.

Examples of the donor (reducing agent) include alkali metals such as Li, Na, K, Rb and Cs, alkaline earth metals such as Be, Mg and Ca, ammonium salts such as tetraethylammonium salt and tetrabutylammonium salt, and hydrogen. Can be mentioned. These donors may be used alone or in admixture of two or more.

The ionic conductive polymer can be obtained by a step including preparing a polymer composition containing a base polymer and a dopant, and kneading and reacting the prepared polymer composition. The kneading conditions are not particularly limited as long as the base polymer reacts with the dopant, but may be 120 to 500 ° C. for 1 minute to 30 hours.

The mass ratio of the base polymer to the dopant (base polymer / dopant) is preferably 99/1 to 20/80, more preferably 95/5 to 30/70, and even more preferably 90/10 to 50/50.

The ionic conductive polymer can also be obtained by treating the base polymer with a dopant. Examples of the method of treating the base polymer with a dopant include a method of evaporating (sublimating) the dopant and bringing the base polymer into contact with the vapor. At this time, the base polymer may be formed into a sheet shape. The conditions for evaporating (sublimating) the dopant can be appropriately set according to the properties of the dopant.

The weight average molecular weight (Mw) of the ionic conductive polymer is preferably 10,000 or more, more preferably 20,000 or more, still more preferably 30,000 or more, preferably 2 million or less, more preferably 1.5 million or less, still more preferably. Is less than 1 million. The weight average molecular weight is a value obtained by measuring by a gel permeation chromatography (GPC) method and converting from a standard polystyrene calibration curve, and the same applies below.

The ionic conductivity of the ionic conductivity polymer is preferably 1 × 10 ^-5 S / cm or more, more preferably 1 × 10 ^-4 S / cm or more, ^still more preferably 1 × 10 ^-4 S / cm or more, from the viewpoint of improving the battery characteristics of the secondary battery. It is 1 × 10 ^-3 S / cm or more. The ionic conductivity of the ionic conductivity polymer may be, for example, 1 × 10 ^-1 S / cm or less. The ionic conductivity can be measured by, for example, an AC impedance measuring device.

The content of the ionic conductive polymer is preferably 60% by mass or more, more preferably 65% by mass or more, still more preferably 70% by mass, based on the total amount of the electrolyte layer, from the viewpoint of further improving the ionic conductivity of the electrolyte layer. It may be 95% by mass or less, or 90% by mass or less.

The electrolyte layer 7 may further contain an electrolyte salt. The electrolyte salt contained in the electrolyte layer 7 may be the same as the above-mentioned electrolyte salt, and may be at least one selected from the group consisting of lithium salt, sodium salt, calcium salt, and magnesium salt. The electrolyte salt is preferably one selected from the group consisting of an imide-based lithium salt, an imide-based sodium salt, an imide-based calcium salt, and an imide-based magnesium salt.

The imide-based lithium salt may be Li [TFSI], Li [FSI] or the like. The imide sodium salt may be Na [TFSI], Na [FSI] or the like. The imide-based calcium salt may be Ca [TFSI] ₂ , Ca [FSI] _2, or the like. The imide-based magnesium salt may be Mg [TFSI] ₂ , Mg [FSI] _2, or the like.

The content of the electrolyte salt is preferably 20% by mass or more based on the total amount of the electrolyte layer from the viewpoint of increasing the conductivity of the electrolyte layer, and enables the secondary battery 1 to be charged and discharged at a high load factor. From the viewpoint, it is more preferably 30% by mass or more. The content of the electrolyte salt may be 10% by mass or more and 60% by mass or less based on the total amount of the electrolyte layer from the viewpoint of preferably producing the electrolyte layer 7.

The thickness of the electrolyte layer 7 is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of increasing the strength and improving the safety. The thickness of the electrolyte layer 7 is preferably 200 μm or less, more preferably 150 μm or less, still more preferably 100 μm or less, from the viewpoint of further reducing the internal resistance of the secondary battery and further improving the large current characteristics.

In another embodiment, the electrode group 2A includes a second battery member (negative electrode member) including a second current collector 11, a negative electrode mixture layer 12, and an electrolyte layer 7 in this order. You can also see that it is. FIG. 3B is a schematic cross-sectional view showing a battery member (negative electrode member) for a secondary battery according to another embodiment, that is, a schematic cross-sectional view showing a second battery member (negative electrode member). As shown in FIG. 3B, the second battery member 14 includes a second current collector 11, a negative electrode mixture layer 12 provided on the second current collector 11, and a negative electrode mixture layer. It is a negative electrode member including an electrolyte layer 7 provided on the 12 in this order. Since the electrolyte layer 7 is the same as the electrolyte layer 7 in the first battery member 13 described above, the description thereof will be omitted below.

The second current collector 11 may be a metal such as aluminum, copper, nickel, or stainless steel, an alloy thereof, or the like. The second current collector 11 is lightweight and has a high weight energy density, and is therefore preferably aluminum or an alloy thereof. The second current collector 11 is preferably copper from the viewpoint of ease of processing into a thin film and cost.

In one embodiment, the negative electrode mixture layer 12 contains a negative electrode active material, an electrolyte salt, and a non-aqueous solvent.

The negative electrode active material may be a carbon material such as graphite or amorphous carbon, a metal material containing tin, silicon or the like, lithium titanate (Li ₄ Ti ₅ O ₁₂ ), metallic lithium or the like.

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 type and content of the electrolyte salt and the non-aqueous solvent contained in the negative electrode mixture layer 12 may be the same as those of the electrolyte salt and the non-aqueous solvent contained in the positive electrode mixture layer 10 described above. The electrolyte salt and the non-aqueous solvent contained in the positive electrode mixture layer 10 and the electrolyte salt and the non-aqueous solvent contained in the negative electrode mixture layer 12 may be the same or different from each other.

The negative electrode mixture layer 12 may further contain a polymer capable of gelling the non-aqueous solvent contained in the negative electrode mixture layer 12. The type and content of the polymer capable of gelling the non-aqueous solvent contained in the negative electrode mixture layer 12 may be the same as that of the polymer capable of gelling the non-aqueous solvent contained in the positive electrode mixture layer 10 described above. .. The polymer capable of gelling the non-aqueous solvent contained in the positive electrode mixture layer 10 and the polymer capable of gelling the non-aqueous solvent contained in the negative electrode mixture layer 12 may be the same or different from each other. May be good.

The negative electrode mixture layer 12 may further contain an ionic liquid. The type and content of the ionic liquid contained in the negative electrode mixture layer 12 may be the same as that of the ionic liquid contained in the positive electrode mixture layer 10 described above. The ionic liquid contained in the positive electrode mixture layer 10 and the ionic liquid contained in the negative electrode mixture layer 12 may be the same as each other or may be different from each other.

In another embodiment, the negative electrode mixture layer 12 contains a negative electrode active material, an electrolyte salt, and an ionic liquid. The types and contents of the negative electrode active material, the electrolyte salt and the ionic liquid may be the same as those in the above-described embodiment.

In each of the above embodiments, the negative electrode mixture layer 12 may further contain a conductive agent, a binder, and the like. The types and contents of the conductive agent and the binder contained in the negative electrode mixture layer 12 may be the same as those of the conductive agent and the binder contained in the positive electrode mixture layer 10 described above. The conductive agent and the binder contained in the positive electrode mixture layer 10 and the conductive agent and the binder contained in the negative electrode mixture layer 12 may be the same or different from each other.

The thickness of the negative electrode mixture layer 12 may be 10 μm or more, 15 μm or more, or 20 μm or more. The thickness of the negative electrode mixture layer may be 60 μm or less, 55 μm or less, or 50 μm or less.

Subsequently, the method for manufacturing the secondary battery 1 described above will be described. The method for manufacturing the secondary battery 1 according to the first embodiment includes a first step of forming a positive electrode mixture layer 10 on a first current collector 9 to obtain a positive electrode 6, and a second current collector 11. It has a second step of forming a negative electrode mixture layer 12 on the negative electrode mixture layer 12 to obtain a negative electrode 8, and a third step of providing an electrolyte layer 7 between the positive electrode 6 and the negative electrode 8.

In the first step, for the positive electrode, for example, after preparing a slurry-like positive electrode mixture containing a material used for the positive electrode mixture layer, the obtained positive electrode mixture is placed on one surface of the first current collector 9. It can be obtained by applying. Examples of the method of applying the positive electrode mixture to the first current collector 9 include a method of applying using an applicator, a metal mask printing method, an electrostatic coating method, a dip coating method, a spray coating method, and a roll coating method. It is a known coating method such as a gravure coating method and a screen printing method.

When the positive electrode mixture layer 10 contains a non-aqueous solvent and a polymer capable of gelling the non-aqueous solvent, the non-aqueous solvent is gelled by a known method after the positive electrode mixture is applied to the first current collector 9. Can be transformed into.

When the positive electrode mixture layer 10 does not contain a non-aqueous solvent, the positive electrode mixture may further contain a dispersion medium in addition to the material used for the positive electrode mixture layer. The dispersion medium is preferably an organic solvent such as N-methyl-2-pyrrolidone. In this case, the positive electrode mixture layer 10 is obtained by applying the positive electrode mixture to the first current collector 9 and then drying the positive electrode mixture (volatilizing the dispersion medium). The method for drying the positive electrode mixture (volatilizing the dispersion medium) is not particularly limited, and a commonly used method can be used.

When the positive electrode mixture layer 10 contains an electrolyte salt and an ionic liquid, the electrolyte salt can be dissolved in the ionic liquid and then added to the slurry together with other materials.

In the second step, the negative electrode can be obtained in the same manner as in the first step described above. That is, it can be obtained by preparing a slurry-like negative electrode mixture containing the material used for the negative electrode mixture layer 12 and then applying the obtained negative electrode mixture on one surface of the second current collector 11. .. When the negative electrode mixture layer 12 contains a non-aqueous solvent and a polymer capable of gelling the non-aqueous solvent, when the negative electrode mixture layer 12 does not contain a non-aqueous solvent, and when the negative electrode mixture layer 12 contains an electrolyte salt and an ionic liquid. The method for producing the negative electrode in the case of containing the above-mentioned solvent may be the same as that in the first step described above.

In the third step, the electrolyte layer 7 is formed by preparing an electrolyte sheet in which an electrolyte composition containing the material used for the electrolyte layer 7 is formed in a sheet shape in one embodiment.

The method for producing the electrolyte sheet includes, for example, a step of obtaining a mixture containing a part or all of the material used for the electrolyte layer 7, a step of doping the polymer (base polymer) with a dopant, and forming the mixture in the form of a sheet. Including the process. The order of each of these steps may be changed, and a plurality of steps may be performed at the same time.

In the method for producing an electrolyte sheet according to one embodiment, first, a base polymer and a dopant are kneaded with other materials if necessary to obtain a mixture. The kneading temperature may be 290 ° C. or higher and may be 340 ° C. or lower. The kneading time may be 20 minutes or more and may be 3 hours or less. By mixing the base polymer and the dopant at a high temperature, the dopant is doped into the base polymer to obtain an ionic conductive polymer. As a result, an electrolyte composition containing an ionic conductive polymer is obtained. Then, the obtained mixture is formed into a sheet by a T-die method or the like. Thereby, an electrolyte sheet can be obtained.

When a sublimable dopant is used as a method for producing the electrolyte sheet according to the other embodiment, the electrolyte sheet can also be produced by the following method. In this method, the base polymer and, if necessary, other materials are first kneaded to obtain a mixture. The kneading temperature may be 290 ° C. or higher and may be 340 ° C. or lower. The kneading time may be 20 minutes or more and may be 3 hours or less. This mixture is formed into a sheet by the T-die method or the like. The dopant is then evaporated and the vapor is brought into contact with the sheet. As a result, the dopant is doped into the base polymer contained in the sheet, and the polymer becomes an ionic conductive polymer. Thereby, an electrolyte sheet can be obtained. The conditions for evaporating (sublimating) the dopant are appropriately set according to the properties of the dopant.

The method of providing the electrolyte layer 7 between the positive electrode 6 and the negative electrode 8 using the electrolyte sheet is, for example, a method of laminating the positive electrode 6, the electrolyte sheet and the negative electrode 8 by, for example, laminating. At this time, the electrolyte layer 7 obtained from the electrolyte sheet is located on the positive electrode mixture layer 10 side of the positive electrode 6 and on the negative electrode mixture layer 12 side of the negative electrode 8, that is, the first current collector 9 and the positive electrode combination. The agent layer 10, the electrolyte layer 7, the negative electrode mixture layer 12 and the second current collector 11 are laminated in this order.

[Second Embodiment]
Next, the secondary battery according to the second embodiment will be described. FIG. 4 is an exploded perspective view showing an electrode group of the secondary battery according to the second embodiment. In FIG. 4, the same reference numerals as those in the first embodiment are assigned, and duplicate description will be omitted. As shown in FIG. 4, the difference between the secondary battery in the second embodiment and the secondary battery in the first embodiment is that the electrode group 2B further includes the bipolar electrode 15. That is, the electrode group 2B includes a positive electrode 6, a first electrolyte layer 7, a bipolar electrode 15, a second electrolyte layer 7, and a negative electrode 8 in this order.

The bipolar electrode 15 includes a third current collector 16, a positive electrode mixture layer 10 provided on the surface of the third current collector 16 on the negative electrode 8 side, and a positive electrode 6 side of the third current collector 16. It is provided with a negative electrode mixture layer 12 provided on the surface.

In the secondary battery of the second embodiment, the electrode group 2B includes a first electrolyte layer 7, a bipolar electrode 15, and a second electrolyte layer 7 in this order, a third battery member (bipolar electrode member). Can be seen as being included. FIG. 5 is a schematic cross-sectional view showing a third battery member (bipolar electrode member). As shown in FIG. 5, the third battery member 17 includes a third current collector 16, a positive electrode mixture layer 10 provided on one surface of the third current collector 16, and a positive electrode mixture. A second electrolyte layer 7 provided on the layer 10 opposite to the third current collector 16, a negative electrode mixture layer 12 provided on the other surface of the third current collector 16, and a negative electrode. It includes a third current collector 16 on the mixture layer 12 and a first electrolyte layer 7 provided on the opposite side.

The third current collector 16 is formed of, for example, a single metal such as aluminum, stainless steel, or titanium, or a clad material obtained by rolling and joining aluminum and copper or stainless steel and copper.

The first electrolyte layer 7 and the second electrolyte layer 7 may be of the same type or different from each other, and are preferably the same type of each other.

As described above, according to the secondary battery battery member of the first battery member 13 (that is, the positive electrode member) and the second battery member 14 (that is, the negative electrode member), the ion conductive polymer is formed in the electrolyte layer 7. Since ionic conductivity is ensured by using it, it is not necessary to use an electrolytic solution (non-aqueous solvent). Then, when such an electrolyte layer 7 is provided on the electrode mixture layers 10 and 12, in one embodiment, the electrode mixture layers 10 and 12 contain a non-aqueous solvent. Also, leakage of non-aqueous solvent can be suppressed. Further, in another embodiment, when the electrode mixture layers 10 and 12 contain an ionic liquid, the electrolyte salt dissolves in the ionic liquid and easily comes into contact with the electrode active material. It is not necessary to use an electrolytic solution (non-aqueous solvent) also in the electrode mixture layer. Therefore, according to these battery members, it is possible to manufacture a secondary battery having excellent safety.

1 ... secondary battery, 2,2A, 2B ... electrode group, 3 ... battery exterior, 4 ... positive electrode current collecting tab, 5 ... negative electrode current collecting tab, 6 ... positive electrode, 7 ... electrolyte layer, 8 ... negative electrode, 9 ... 1st current collector, 10 ... positive electrode mixture layer, 11 ... second current collector, 12 ... negative electrode mixture layer, 13 ... first battery member, 14 ... second battery member, 15 ... bipolar electrode , 16 ... 3rd current collector, 17 ... 3rd battery member.

Claims (5)

With the current collector
The electrode mixture layer provided on the current collector and
An electrolyte layer provided on the electrode mixture layer is provided.
The electrode mixture layer contains an electrode active material, an electrolyte salt, and a non-aqueous solvent.
A battery member for a secondary battery, wherein the electrolyte layer contains an ionic conductive polymer. The battery member according to claim 1, wherein the electrode mixture layer further contains a polymer capable of gelling the non-aqueous solvent. The battery member according to claim 1 or 2, wherein the electrode mixture layer further contains an ionic liquid. With the current collector
The electrode mixture layer provided on the current collector and
An electrolyte layer provided on the electrode mixture layer is provided.
The electrode mixture layer contains an electrode active material, an electrolyte salt, and an ionic liquid.
A battery member for a secondary battery, wherein the electrolyte layer contains an ionic conductive polymer. A secondary battery comprising the battery member according to any one of claims 1 to 4.

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