WO2019013027A1

WO2019013027A1 - Secondary battery, battery pack, electric vehicle, electrical energy storage system, electric tool and electronic device

Info

Publication number: WO2019013027A1
Application number: PCT/JP2018/025044
Authority: WO
Inventors: 洋樹三田; 一正武志
Original assignee: 株式会社村田製作所
Priority date: 2017-07-11
Filing date: 2018-07-02
Publication date: 2019-01-17

Abstract

This secondary battery comprises a positive electrode, a negative electrode, and an electrolyte layer which is configured such that: (A) an electrolyte solution, a polymer compound and a plurality of fibrous substances are contained therein; (B) the electrolyte solution is held by the polymer compound; and (C) the plurality of fibrous substances contain celluloses having fiber diameters of 40 nm or less.

Description

Secondary battery, battery pack, electric vehicle, electric power storage system, electric tool and electronic device

The present technology relates to a secondary battery provided with an electrolytic solution and an electrolyte layer containing a polymer compound, and a battery pack, an electric vehicle, an electric power storage system, an electric tool, and an electronic device using the secondary battery.

2. Description of the Related Art Various electronic devices such as mobile phones are widely used, and there is a demand for downsizing, weight reduction and long life of the electronic devices. Therefore, development of a secondary battery which is compact and lightweight and capable of obtaining high energy density is being promoted as a power source.

Secondary batteries are considered not only for electronic devices but also for other applications. For example, a battery pack detachably mounted on an electronic device or the like, an electric vehicle such as an electric vehicle, an electric power storage system such as a household electric power server, and an electric tool such as an electric drill.

The secondary battery includes a positive electrode, a negative electrode, and an electrolyte layer which is a gel electrolyte, and the electrolyte layer contains an electrolytic solution and a polymer compound (so-called matrix polymer). This is because leakage of the electrolytic solution is prevented as compared with the case where the electrolytic solution which is a liquid electrolyte is used as it is.

Since the composition of the electrolyte layer has a great influence on the battery characteristics of the secondary battery, various studies have been made regarding the composition of the electrolyte layer.

Specifically, in order to improve cycle characteristics and the like, fibrous insolubles are contained in the electrolyte layer, and a superfine fibrous porous polymer matrix is used as the polymer compound (for example, See Patent Documents 1 and 2.).

Patent No. 4081895 Japanese Patent Publication No. 2003-533861

Electronic devices and the like on which a secondary battery is mounted are becoming increasingly sophisticated and multifunctional. Along with this, the frequency of use of electronic devices and the like is increasing, and the use environment of electronic devices and the like is expanding. Therefore, the battery characteristics of the secondary battery still have room for improvement.

The present technology has been made in view of such problems, and an object thereof is to provide a secondary battery, a battery pack, an electric vehicle, an electric power storage system, an electric tool, and an electronic device capable of obtaining excellent battery characteristics. It is.

The secondary battery of the present technology includes a positive electrode, a negative electrode, (A) an electrolytic solution, a polymer compound, and a plurality of fibrous substances, and (B) the electrolytic solution is held by the polymer compound; A plurality of fibrous substances are provided with an electrolyte layer containing cellulose having a fiber diameter of 40 nm or less.

Each of the battery pack, the electric vehicle, the electric power storage system, the electric power tool, and the electronic device of the present technology includes a secondary battery, and the secondary battery has the same configuration as that of the above-described secondary battery of the present technology. .

According to the secondary battery of the present technology, the electrolyte layer contains a plurality of fibrous substances together with the electrolytic solution and the polymer compound, and the plurality of fibrous substances contain cellulose having a fiber diameter of 40 nm or less. , Excellent battery characteristics can be obtained. In addition, similar effects can be obtained in each of the battery pack, the electric vehicle, the electric power storage system, the electric tool, and the electronic device of the present technology.

In addition, the effect described here is not necessarily limited, and may be any effect described in the present technology.

It is a perspective view showing composition of a rechargeable battery of one embodiment of this art. FIG. 3 is a cross-sectional view showing a configuration of a wound electrode body along a II-II line shown in FIG. It is a perspective view showing the composition of the example of application of a rechargeable battery (battery pack: single battery). It is a block diagram showing the structure of the battery pack shown in FIG. It is a block diagram showing the composition of the example of application of a rechargeable battery (battery pack: group battery). It is a block diagram showing the composition of the example of application of a rechargeable battery (electric vehicle). It is a block diagram showing the composition of the example of application of a rechargeable battery (electric power storage system). It is a block diagram showing the composition of the example of application of a rechargeable battery (electric tool).

Hereinafter, an embodiment of the present technology will be described in detail with reference to the drawings. The order to be described is as follows.

1. Secondary battery 1-1. Configuration 1-2. Operation 1-3. Manufacturing method 1-4. Action and effect 2. Applications of Secondary Battery 2-1. Battery pack (single cell)
2-2. Battery pack (battery pack)
2-3. Electric vehicle 2-4. Power storage system 2-5. Electric tool

<1. Secondary battery>
First, a secondary battery according to an embodiment of the present technology will be described.

The secondary battery described here is, for example, a secondary battery using lithium as an electrode reactant. The "electrode reactant" is a substance involved in an electrode reaction (charge-discharge reaction).

More specifically, the secondary battery is a lithium ion secondary battery in which a battery capacity (capacity of the negative electrode) is obtained by utilizing a lithium absorption phenomenon and a lithium release phenomenon.

<1-1. Configuration>
First, the configuration of the secondary battery will be described.

FIG. 1 shows a perspective view of the secondary battery, and FIG. 2 is an enlarged sectional view of the wound electrode body 10 taken along the line II-II shown in FIG. In addition, in FIG. 1, in order to make the structure of the winding electrode body 10 and the structure of the exterior member 20 intelligible, the state which the winding electrode body 10 and the exterior member 20 mutually separated is shown.

This secondary battery is, for example, a laminate in which a wound electrode body 10 as a battery element is housed inside a flexible (or flexible) film-like package member 20 as shown in FIG. It is a film type secondary battery.

[Exterior member]
The exterior member 20 is, for example, a single film that can be folded in the direction of the arrow R as shown in FIG. 1, and the exterior member 20 accommodates, for example, the wound electrode body 10. The hollow 20U of the

The exterior member 20 is, for example, a laminate film in which a surface protection layer, a metal layer, and a fusion layer are laminated in this order from the outside. In the manufacturing process of the secondary battery, for example, as described later, after the package member 20 is folded so that the fusion layers face each other via the wound electrode body 10, the outer peripheral edge portion of the fusion layer They are fused together.

The surface protective layer contains, for example, any one or more of films such as nylon and polyethylene terephthalate. The metal layer contains, for example, any one or more of metal foils such as aluminum foil. The fusion layer contains, for example, any one or more of films such as polyethylene and polypropylene.

Among them, the exterior member 20 is preferably an aluminum laminate film in which a polyethylene film, an aluminum foil, and a nylon film are laminated in this order from the outside.

However, the exterior member 20 may be, for example, a laminate film having another laminated structure, a single layer polymer film such as a polypropylene film, or a single layer metal foil such as an aluminum foil. Moreover, the exterior member 20 is, for example, two films, and the two films may be attached to each other via, for example, an adhesive.

[Wound electrode body]
For example, as shown in FIG. 2, after the positive electrode 13 and the negative electrode 14 are stacked on each other via the separator 15 and the electrolyte layer 16, the wound electrode body 10 has the positive electrode 13, the negative electrode 14, the separator 15, and the electrolyte. The layer 16 is formed by winding. The outermost periphery of the wound electrode body 10 is protected by, for example, a protective tape 17.

[Positive electrode lead and negative electrode lead]
The positive electrode lead 11 is connected to the positive electrode 13, and the positive electrode lead 11 is drawn out from the inside of the exterior member 20 to the outside. The positive electrode lead 11 contains, for example, one or more of conductive materials such as aluminum. The shape of the positive electrode lead 11 is, for example, a thin plate or a mesh.

The negative electrode lead 12 is connected to the negative electrode 14, and the negative electrode lead 12 is drawn out from the inside of the package member 20 to the outside. The lead-out direction of the negative electrode lead 12 is, for example, the same as the lead-out direction of the positive electrode lead 11. The negative electrode lead 12 contains, for example, one or more of conductive materials such as copper, nickel and stainless steel. The shape of the negative electrode lead 12 is, for example, the same as the shape of the positive electrode lead 31.

[Adhesive film]
For example, an adhesive film 21 is inserted between the exterior member 20 and the positive electrode lead 11 in order to prevent the entry of the outside air. The adhesive film 21 contains, for example, one or more of materials having adhesiveness to the positive electrode lead 11, and more specifically, contains a polyolefin resin or the like. The polyolefin resin is, for example, any one or more of polyethylene, polypropylene, modified polyethylene and modified polypropylene.

For example, an adhesive film 22 having the same function as the adhesive film 21 is inserted between the exterior member 20 and the negative electrode lead 12. The forming material of the adhesive film 22 is, for example, the same as the forming material of the adhesive film 21.

[Positive electrode]
For example, as shown in FIG. 2, the positive electrode 13 includes a positive electrode current collector 13A and two positive electrode active material layers 13B provided on both sides of the positive electrode current collector 13A. However, only one positive electrode active material layer 13B may be provided on one side of the positive electrode current collector 13A.

(Positive current collector)
The positive electrode current collector 13A contains, for example, one or more of conductive materials. The type of conductive material is not particularly limited, and is, for example, a metal material such as aluminum, nickel and stainless steel. The positive electrode current collector 13A may be a single layer or a multilayer.

(Positive electrode active material layer)
The positive electrode active material layer 13B contains, as a positive electrode active material, any one or two or more kinds of positive electrode materials capable of inserting and extracting lithium. However, the positive electrode active material layer 13B may further contain one or more of other materials such as a positive electrode binder and a positive electrode conductive agent.

(Positive electrode active material (positive electrode material))
The positive electrode material is preferably a lithium-containing compound. This is because a high energy density can be obtained. The "lithium-containing compound" is a generic term for compounds containing lithium as a constituent element. The type of lithium-containing compound is not particularly limited, and examples thereof include lithium-containing composite oxides and lithium-containing phosphoric acid compounds.

The term "lithium-containing composite oxide" is a generic term for oxides containing lithium and one or more other elements as constituent elements, and, for example, a crystal of layered rock salt type, spinel type, etc. It has a structure. The "lithium-containing phosphoric acid compound" is a generic term for a phosphoric acid compound containing lithium and one or more other elements as constituent elements, and has, for example, a crystal structure such as an olivine type. In addition, "other elements" are elements other than lithium.

The type of the other element is not particularly limited, but among them, one or more of elements belonging to Groups 2 to 15 in the long period periodic table are preferable. Specifically, the other elements are, for example, nickel (Ni), cobalt (Co), manganese (Mn) and iron (Fe). This is because a high voltage can be obtained.

The lithium-containing composite oxide having a layered rock salt type crystal structure is, for example, a compound represented by each of the following formulas (1) to (3).

Li _a Mn _(1-bc) Ni _b M 1 _c O _(2-d) F _e (1)
(M1 is cobalt (Co), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc) At least one of (Zn), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W), a to e is 0.8 The following conditions are satisfied: a ≦ 1.2, 0 <b <0.5, 0 ≦ c ≦ 0.5, (b + c) <1, −0.1 ≦ d ≦ 0.2 and 0 ≦ e ≦ 0.1. However, the composition of lithium varies depending on the charge and discharge state, and a is a value of a completely discharged state.)

Li _a Ni _(1-b) M 2 _b O _(2-c) F _d (2)
(M2 is cobalt (Co), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper) And at least one of (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr) and tungsten (W), wherein a to d is 0.8 ≦ a ≦ 1.2, 0.005 ≦ b ≦ 0.5, −0.1 ≦ c ≦ 0.2 and 0 ≦ d ≦ 0.1, provided that the composition of lithium depends on the charge and discharge state Differently, a is the value of the fully discharged state)

Li _a Co _(1-b) M3 _b O _(2-c) F _d (3)
(M3 represents nickel (Ni), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper) And at least one of (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr) and tungsten (W), wherein a to d is 0.8 ≦ a ≦ 1.2, 0 ≦ b <0.5, −0.1 ≦ c ≦ 0.2 and 0 ≦ d ≦ 0.1, provided that the composition of lithium differs depending on the charge / discharge state, a is the value of the completely discharged state)

Specific examples of the lithium-containing composite oxide having a layered rock salt type crystal structure are LiNiO ₂ , LiCoO ₂ , LiCo _0.98 Al _0.01 Mg _0.01 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ LiNi _0.33 Co _0.33 Mn _0.33 O ₂ , Li _1.2 Mn _0.52 Co _0.175 Ni _0.1 O ₂ and Li _1.15 (Mn _0.65 Ni _0.22 Co _0.13 ) O ₂ and the like.

When the lithium-containing composite oxide having a layered rock salt type crystal structure contains nickel, cobalt, manganese and aluminum as constituent elements, the atomic ratio of nickel is preferably 50 atomic% or more. This is because a high energy density can be obtained.

The lithium-containing composite oxide having a spinel crystal structure is, for example, a compound represented by the following formula (4).

Li _a Mn _(2-b) M 4 _b O _c F _d (4)
(M4 is cobalt (Co), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper) And at least one of (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr) and tungsten (W), wherein a to d are 0.9 ≦ a ≦ 1.1, 0 ≦ b ≦ 0.6, 3.7 ≦ c ≦ 4.1 and 0 ≦ d ≦ 0.1, provided that the composition of lithium varies depending on the charge / discharge state, a Is the value of the completely discharged state.)

A specific example of the lithium-containing composite oxide having a spinel type crystal structure is LiMn ₂ O ₄ or the like.

The lithium-containing phosphoric acid compound having an olivine type crystal structure is, for example, a compound represented by the following formula (5).

Li _a M5PO ₄ (5)
(M5 is cobalt (Co), manganese (Mn), iron (Fe), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), niobium) At least one of (Nb), copper (Cu), zinc (Zn), molybdenum (Mo), calcium (Ca), strontium (Sr), tungsten (W) and zirconium (Zr), a is 0.9 ≦ a ≦ 1.1, provided that the composition of lithium varies depending on the charge and discharge state, and a is a value of a completely discharged state)

Specific examples of the lithium-containing phosphoric acid compound having an olivine type crystal structure are LiFePO ₄ , LiMnPO ₄ , LiFe _0.5 Mn _0.5 PO ₄ and LiFe _0.3 Mn _0.7 PO ₄ and the like.

In addition, the compound etc. which are represented by following formula (6) may be sufficient as lithium containing complex oxide.

(Li ₂ MnO ₃ ) _x (LiMnO ₂ ) _1-x (6)
(X satisfies 0 ≦ x ≦ 1. However, the composition of lithium varies depending on the charge and discharge state, and x is a value of a completely discharged state)

(Other positive electrode materials)
The positive electrode material may be, for example, an oxide, a disulfide, a chalcogenide, or a conductive polymer. The oxides are, for example, titanium oxide, vanadium oxide and manganese dioxide. Examples of the disulfide include titanium disulfide and molybdenum sulfide. The chalcogenide is, for example, niobium selenide or the like. The conductive polymer is, for example, sulfur, polyaniline and polythiophene.

(Positive electrode binder)
The positive electrode binder contains, for example, one or more of synthetic rubber and polymer compound. The synthetic rubber is, for example, styrene butadiene rubber, fluorine rubber and ethylene propylene diene. The high molecular compounds are, for example, polyvinylidene fluoride and polyimide.

(Positive electrode conductive agent)
The positive electrode conductive agent contains, for example, one or more of conductive materials such as a carbon material. This carbon material is, for example, graphite, carbon black, acetylene black and ketjen black. However, the positive electrode conductive agent is not limited to a carbon material as long as it is a conductive material, and may be a metal material, a conductive polymer, or the like.

[Negative electrode]
For example, as shown in FIG. 2, the negative electrode 14 includes a negative electrode current collector 14A and two negative electrode active material layers 14B provided on both sides of the negative electrode current collector 14A. However, only one negative electrode active material layer 14B may be provided on one side of the negative electrode current collector 14A.

(Negative current collector)
The negative electrode current collector 14A contains, for example, one or more of conductive materials. The type of conductive material is not particularly limited, but is, for example, metal materials such as copper, aluminum, nickel and stainless steel. The negative electrode current collector 14A may be a single layer or a multilayer.

The surface of the negative electrode current collector 14A is preferably roughened. This is because the adhesion of the negative electrode active material layer 14B to the negative electrode current collector 14A is improved by utilizing the so-called anchor effect. In this case, the surface of the negative electrode current collector 14A may be roughened at least in a region facing the negative electrode active material layer 14B. The roughening method is, for example, a method of forming fine particles using electrolytic treatment. In the electrolytic treatment, since fine particles are formed on the surface of the negative electrode current collector 14A by using the electrolytic method in the electrolytic cell, unevenness is provided on the surface of the negative electrode current collector 14A. The copper foil produced by the electrolytic method is generally called an electrolytic copper foil.

(Anode active material layer)
The negative electrode active material layer 14B contains, as a negative electrode active material, any one kind or two or more kinds of negative electrode materials capable of inserting and extracting lithium. However, the negative electrode active material layer 14B may further contain one or more of other materials such as a negative electrode binder and a negative electrode conductive agent.

In order to prevent lithium metal from unintentionally depositing on the surface of the negative electrode 14 during charging, the chargeable capacity of the negative electrode material is preferably larger than the discharge capacity of the positive electrode 13. That is, the electrochemical equivalent of the negative electrode material capable of inserting and extracting lithium is preferably larger than the electrochemical equivalent of the positive electrode 13.

(Anode active material (negative electrode material))
The type of negative electrode material is not particularly limited as long as it is a material capable of inserting and extracting lithium.

(Carbon material)
The negative electrode material is, for example, a carbon material. The "carbon material" is a general term for materials containing carbon as a constituent element. This is because a high energy density can be stably obtained because the crystal structure of the carbon material hardly changes significantly at the time of lithium storage and lithium release. In addition, since the carbon material also functions as a negative electrode conductive agent, the conductivity of the negative electrode active material layer 14B is improved.

The carbon material is, for example, graphitizable carbon, non-graphitizable carbon, graphite and the like. However, the spacing of the (002) plane relating to the non-graphitizable carbon is preferably 0.37 nm or more, and the spacing of the (002) plane relating to the graphite is preferably 0.34 nm or less. More specifically, the carbon material is, for example, pyrolytic carbons, cokes, glassy carbon fibers, organic polymer compound fired bodies, activated carbon, carbon blacks and the like. The cokes include pitch coke, needle coke and petroleum coke. The organic polymer compound fired body is a fired product obtained by firing (carbonizing) a polymer compound such as a phenol resin and furan resin at an appropriate temperature. In addition, the carbon material may be, for example, low crystalline carbon heat-treated at a temperature of about 1000 ° C. or lower, or amorphous carbon. The shape of the carbon material may be any of fibrous, spherical, granular and scaly.

(Metal-based material)
The negative electrode material is, for example, a metal-based material. The "metal-based material" is a generic name of a material containing one or more of metal elements and metalloid elements as constituent elements. This is because a high energy density can be obtained.

The metal-based material may be any one of an element, an alloy and a compound, two or more of them, or a material having at least a part of one or two or more of them. . However, in addition to the material which consists of 2 or more types of metal elements, the alloy also contains the material containing 1 or more types of metal elements, and 1 or more types of metalloid elements. The alloy may also contain nonmetallic elements. The structure of this metal-based material is, for example, a solid solution, a eutectic (eutectic mixture), an intermetallic compound, and a coexistence of two or more thereof.

Metal elements and metalloid elements are, for example, metal elements and metalloid elements that can form an alloy with lithium. Specifically, the metal element and the metalloid element are, for example, magnesium (Mg), boron (B), aluminum (Al), gallium (Ga), indium (In), silicon (Si), germanium (Ge), Tin (Sn), lead (Pb), bismuth (Bi), cadmium (Cd), silver (Ag), zinc, hafnium (Hf), zirconium, yttrium (Y), palladium (Pd), platinum (Pt), etc. is there.

Among them, one or both of silicon and tin are preferred. Because the ability to insert and extract lithium is excellent, extremely high energy density can be obtained.

The material containing one or both of silicon and tin as a constituent element may be any of silicon alone, an alloy and a compound, or any of tin alone, an alloy and a compound, and among them Or a material having at least a part of one or two or more of them. The term "single substance" described herein means a single substance (which may contain a trace amount of impurities) in a general sense, and therefore means that the purity is necessarily 100%. is not.

The alloy of silicon is, for example, one of tin, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, chromium and the like as constituent elements other than silicon or It contains two or more types. The compound of silicon contains, for example, one or more of carbon, oxygen, and the like as a constituent element other than silicon. The compound of silicon may contain, for example, one or more of a series of elements described for the alloy of silicon as a constituent element other than silicon.

Specific examples of the alloy of silicon and the compound of silicon are SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ , MnSi ₂ , NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _v (0 <v ≦ 2), LiSiO and the like. In addition, _v in SiOv may be 0.2 <v <1.4.

The alloy of tin is, for example, one of silicon, nickel, copper, iron, cobalt, manganese, zinc, indium, silver, titanium, germanium, bismuth, antimony, chromium and the like as a constituent element other than tin or the like It contains two or more types. The compound of tin contains, for example, one or more of carbon, oxygen, and the like as a constituent element other than tin. The compound of tin may contain, for example, one or more of the series of elements described for the alloy of tin as a constituent element other than tin.

Specific examples of alloys of tin and compounds of tin are SnO _w (0 <w ≦ 2), SnSiO ₃ , LiSnO and Mg ₂ Sn.

In particular, the material containing tin as a constituent element is preferably, for example, a material (tin-containing material) containing a second constituent element and a third constituent element together with tin as the first constituent element. The second constituent element is, for example, cobalt, iron, magnesium, titanium, vanadium, chromium, manganese, nickel, copper, zinc, gallium, zirconium, niobium, molybdenum, silver, indium, cesium (Ce), hafnium (Hf), It contains one or more of tantalum, tungsten, bismuth, silicon and the like. The third constituent element contains, for example, one or more of boron, carbon, aluminum, phosphorus and the like. This is because high battery capacity and excellent cycle characteristics can be obtained.

Among them, the tin-containing material is preferably a material (tin-cobalt carbon-containing material) containing tin, cobalt and carbon as constituent elements. In this tin-cobalt carbon-containing material, for example, the content of carbon is 9.9% to 29.7% by mass, and the ratio of the content of tin and cobalt (Co / (Sn + Co)) is 20% to 70% by mass is there. This is because a high energy density can be obtained.

The tin-cobalt carbon-containing material has a phase containing tin, cobalt and carbon, and the phase is preferably low crystalline or amorphous. Since this phase is a phase capable of reacting with lithium (reactive phase), excellent properties are obtained due to the presence of the reactive phase. The half-width (diffraction angle 2θ) of the diffraction peak obtained by X-ray diffraction of this reaction phase is 1 ° or more when the CuKα ray is used as the specific X-ray and the drawing speed is 1 ° / min. Is preferred. While lithium is occluded and released more smoothly, the reactivity with the electrolytic solution is reduced. In addition to the low crystalline or amorphous phase, the tin-cobalt carbon-containing material may include a phase containing a single element or a part of each constituent element.

As to whether the diffraction peak obtained by X-ray diffraction is a diffraction peak corresponding to a reaction phase capable of reacting with lithium, compare X-ray diffraction charts before and after the electrochemical reaction with lithium. It can be easily determined. For example, if the position of the diffraction peak changes before and after the electrochemical reaction with lithium, it is a diffraction peak corresponding to the reaction phase capable of reacting with lithium. In this case, for example, the diffraction peak of the low crystalline or amorphous reaction phase is detected between 2θ = 20 ° and 50 °. This reaction phase contains, for example, the above-described constituent elements, and is considered to be low in crystallization or amorphization mainly due to the presence of carbon.

In the tin-cobalt carbon-containing material, it is preferable that at least a part of carbon which is a constituent element is bonded to a metal element or a metalloid element which is another constituent element. This is because aggregation or crystallization of tin or the like is suppressed. The bonding state of elements can be confirmed using, for example, X-ray photoelectron spectroscopy (XPS). In a commercially available apparatus, for example, Al-Kα rays or Mg-Kα rays are used as soft X-rays. When at least a part of carbon is bonded to a metal element or a metalloid element or the like, a peak of a synthetic wave of carbon 1s orbital (C1s) appears in an energy region lower than 284.5 eV. In addition, it is assumed that the energy calibration is performed so that the peak of 4f orbit (Au4f) of gold atom is obtained at 84.0 eV. Under the present circumstances, since surface contamination carbon exists in the substance surface normally, the peak of C1s of the surface contamination carbon is made into 284.8 eV, and the peak is used as an energy standard. In XPS measurement, the waveform of the C1s peak is obtained in a state including the peak due to surface contamination carbon and the peak due to carbon in the tin-cobalt carbon-containing material. Therefore, for example, the peaks are separated by analyzing the peaks using commercially available software. In the analysis of the waveform, the position of the main peak present on the lowest binding energy side is used as the energy reference (284.8 eV).

The tin-cobalt carbon-containing material is not limited to a material whose constituent elements are only tin, cobalt and carbon. The tin-cobalt-carbon-containing material may be, for example, in addition to tin, cobalt and carbon, any of silicon, iron, nickel, chromium, indium, niobium, germanium, titanium, molybdenum, aluminum, phosphorus, gallium and bismuth etc. You may contain 1 type or 2 types or more as a constitutent element.

Besides tin-cobalt carbon-containing materials, materials containing tin, cobalt, iron and carbon as constituent elements (tin-cobalt-iron-carbon-containing materials) are also preferable. The composition of this tin-cobalt-iron-carbon-containing material is optional. For example, when the content of iron is set to be small, the content of carbon is 9.9% by mass to 29.7% by mass, and the content of iron is 0.3% by mass to 5.9% by mass The content ratio of tin and cobalt (Co / (Sn + Co)) is 30% by mass to 70% by mass. In addition, when the content of iron is set to be large, the content of carbon is 11.9 mass% to 29.7 mass%, and the content ratio of tin, cobalt and iron ((Co + Fe) / (Sn + Co + Fe)) Is 26.4% by mass to 48.5% by mass, and the ratio of the content of cobalt and iron (Co / (Co + Fe)) is 9.9% by mass to 79.5% by mass. In such a composition range, high energy density can be obtained. The physical properties (such as half width) of the tin-cobalt-iron-carbon-containing material are the same as the physical properties of the above-mentioned tin-cobalt-carbon-containing material.

(Combined use of carbon material and metal material)
Among them, the negative electrode material preferably contains both a carbon material and a metal-based material for the following reasons.

Metal-based materials, in particular, materials containing one or both of silicon and tin as constituent elements have the advantage of high theoretical capacity, but have the concern that they tend to undergo extensive expansion and contraction during charge and discharge. On the other hand, carbon materials have the concern that the theoretical capacity is low, but they have the advantage of being difficult to expand and contract during charge and discharge. Therefore, by using the carbon material and the metal-based material in combination, expansion and contraction at the time of charge and discharge are suppressed while securing a high theoretical capacity (that is, battery capacity).

(Other negative electrode materials)
The negative electrode material may be, for example, a metal oxide and a polymer compound. The metal oxide is, for example, iron oxide, ruthenium oxide and molybdenum oxide. The polymer compounds are, for example, polyacetylene, polyaniline and polypyrrole.

(Negative electrode binder and negative electrode conductive agent)
The details of the negative electrode binder are, for example, the same as the details of the positive electrode binder described above. Further, details of the negative electrode conductive agent are, for example, the same as the details of the negative electrode conductive agent described above.

In the secondary battery, as described above, in order to prevent lithium metal from being unintentionally deposited on the surface of the negative electrode 14 during charging, electricity of the negative electrode material capable of inserting and extracting lithium The chemical equivalent is greater than the electrochemical equivalent of the positive electrode. In addition, when the open circuit voltage at the full charge (ie, the battery voltage) is 4.25 V or more, the same positive electrode active material is used as compared to the case where the open circuit voltage at the full charge is 4.20 V. The amount of the positive electrode active material and the amount of the negative electrode active material are mutually adjusted in consideration of the fact that the amount of release of lithium per unit mass is increased. This gives a high energy density.

[Separator]
For example, as shown in FIG. 2, the separator 15 is disposed between the positive electrode 13 and the negative electrode 14, and allows lithium ions to pass while preventing a short circuit of the current caused by the contact of the both electrodes.

The separator 15 contains, for example, one or more types of porous films such as synthetic resin and ceramic, and may be a laminated film of two or more types of porous films. Synthetic resins are, for example, polytetrafluoroethylene, polypropylene and polyethylene.

In particular, the separator 15 may include, for example, the above-described porous membrane (base layer) and a polymer compound layer provided on one side or both sides of the base layer. This is because the adhesion of the separator 15 to each of the positive electrode 13 and the negative electrode 14 is improved, so distortion of the wound electrode body 10 is suppressed. Thereby, the decomposition reaction of the electrolytic solution is suppressed, and the leakage of the electrolytic solution impregnated in the base material layer is also suppressed. Therefore, the electric resistance is less likely to increase even if charge and discharge are repeated, and the secondary battery is It becomes difficult to swell.

The polymer compound layer contains, for example, a polymer compound such as polyvinylidene fluoride. It is because it is excellent in physical strength and electrochemically stable. However, the polymer compound may be other than polyvinylidene fluoride. In the case of forming the polymer compound layer, for example, a solution in which the polymer compound is dissolved in an organic solvent or the like is applied to the base material layer, and then the base material layer is dried. In addition, after a base material layer is immersed in a solution, the base material layer may be dried.

The polymer compound layer may contain, for example, one or more of insulating particles such as inorganic particles. This is because the safety of the secondary battery is improved. The type of inorganic particles is not particularly limited, and examples thereof include aluminum oxide and aluminum nitride.

[Electrolyte layer]
The electrolyte layer 16 contains an electrolytic solution, a polymer compound, and a plurality of fibrous materials. However, the electrolyte layer 16 may further contain any one or more of other materials such as additives.

The electrolyte layer 16 described here is a so-called gel electrolyte. That is, in the electrolyte layer 16, each of the electrolytic solution and the plurality of fibrous substances is dispersed, and the electrolytic solution is held by the polymer compound. This is because high ionic conductivity (for example, 1 mS / cm or more at room temperature) can be obtained, and leakage of the electrolytic solution can be prevented. The plurality of fibrous substances may be held by the polymer compound or may not be held by the polymer compound. Also, the plurality of fibrous substances may hold an electrolytic solution.

For example, as shown in FIG. 2, the electrolyte layer 16 is disposed between the positive electrode 13 and the separator 15 and disposed between the negative electrode 14 and the separator 15. However, the electrolyte layer 16 may be disposed, for example, only between the positive electrode 13 and the separator 15, or may be disposed only between the negative electrode 14 and the separator 15.

(Electrolyte solution)
The electrolyte contains a solvent and an electrolyte salt. However, the electrolytic solution may further contain any one or more of other materials such as additives.

(solvent)
The solvent contains any one or more kinds of non-aqueous solvents such as organic solvents. The electrolyte containing a non-aqueous solvent is a so-called non-aqueous electrolyte.

Nonaqueous solvents are, for example, cyclic carbonates, linear carbonates, lactones, linear carboxylic esters and mononitrile compounds. This is because excellent battery capacity, cycle characteristics and storage characteristics can be obtained.

Cyclic carbonates are, for example, ethylene carbonate, propylene carbonate and butylene carbonate. The chain carbonate is, for example, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate and methyl propyl carbonate. Lactones are, for example, γ-butyrolactone and γ-valerolactone. The chain carboxylic acid ester is, for example, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethylacetate and ethyl trimethylacetate. The mononitrile compounds are, for example, acetonitrile, methoxyacetonitrile, 3-methoxypropionitrile and the like.

Other non-aqueous solvents are, for example, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1 And 4-dioxane, N, N-dimethylformamide, N-methyl pyrrolidinone, N-methyl oxazolidinone, N, N'-dimethyl imidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate and dimethyl sulfoxide and the like. It is because the same advantage is obtained.

Among them, the non-aqueous solvent preferably contains one or more selected from ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate. This is because high battery capacity, excellent cycle characteristics and excellent storage characteristics can be obtained. In this case, high viscosity (high dielectric constant) solvents such as ethylene carbonate and propylene carbonate (for example, relative permittivity ε ≧ 30) and low viscosity solvents such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate (for example, viscosity The combination with ≦ 1 mPa · s) is more preferable. This is because the dissociative nature of the electrolyte salt and the mobility of the ions are improved.

Also, the non-aqueous solvent is, for example, unsaturated cyclic carbonate, halogenated carbonate, sulfonic acid ester, acid anhydride, dicyano compound (dinitrile compound), diisocyanate compound, phosphoric acid ester and carbon-carbon triple bond chain compound is there. This is because the chemical stability of the electrolytic solution is improved.

An unsaturated cyclic carbonate is a cyclic carbonate having one or more unsaturated bonds (carbon-carbon double bonds). The unsaturated cyclic carbonate is, for example, vinylene carbonate, vinyl ethylene carbonate and methylene ethylene carbonate. The content of the unsaturated cyclic carbonate in the non-aqueous solvent is not particularly limited, and is, for example, 0.01% by weight to 10% by weight.

The halogenated carbonate is a cyclic or chain carbonate containing one or more halogen elements as a constituent element. When the halogenated carbonate ester contains two or more halogens as constituent elements, the number of kinds of two or more halogens may be only one or two or more. Cyclic halogenated carbonates are, for example, 4-fluoro-1,3-dioxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one. The chain halogenated carbonates are, for example, fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate and difluoromethyl methyl carbonate. The content of the halogenated carbonate in the non-aqueous solvent is not particularly limited, and is, for example, 0.01% by weight to 50% by weight.

Sulfonic acid esters are, for example, monosulfonic acid esters and disulfonic acid esters. The content of sulfonic acid ester in the non-aqueous solvent is not particularly limited, and is, for example, 0.01% by weight to 10% by weight.

The monosulfonic acid ester may be a cyclic monosulfonic acid ester or a linear monosulfonic acid ester. Cyclic monosulfonic acid esters are, for example, sultones such as 1,3-propane sultone and 1,3-propene sultone. The linear monosulfonic acid ester is, for example, a compound in which a cyclic monosulfonic acid ester is cleaved halfway. The disulfonic acid ester may be a cyclic disulfonic acid ester or a linear disulfonic acid ester.

The acid anhydride is, for example, carboxylic acid anhydride, disulfonic acid anhydride and carboxylic acid sulfonic acid anhydride. Carboxylic anhydrides are, for example, succinic anhydride, glutaric anhydride and maleic anhydride. Examples of disulfonic anhydride include anhydrous ethanedisulfonic acid and anhydrous propanedisulfonic acid. Carboxylic acid sulfonic acid anhydrides are, for example, sulfobenzoic anhydride, sulfopropionic anhydride and sulfobutyric anhydride. The content of the acid anhydride in the non-aqueous solvent is not particularly limited, and is, for example, 0.5% by weight to 5% by weight.

The dinitrile compound is, for example, a compound represented by NC-R1-CN (R1 is any of an alkylene group and an arylene group). The dinitrile compounds are, for example, succinonitrile _{_{(NC-C 2 H 4 -CN}} ), glutaronitrile _{_{(NC-C 3 H 6 -CN}} ), adiponitrile _{_{(NC-C 4 H 8 -CN}} ) and phthalonitrile ( NC-C ₆ H ₄ -CN) and the like. The content of the dinitrile compound in the non-aqueous solvent is not particularly limited, and is, for example, 0.5% by weight to 5% by weight.

The diisocyanate compound is, for example, a compound represented by OCN-R2-NCO (R2 is any of an alkylene group and an arylene group). The diisocyanate compound is, for example, hexamethylene diisocyanate (OCN-C ₆ H ₁₂ -NCO). The content of the diisocyanate compound in the non-aqueous solvent is not particularly limited, and is, for example, 0.5% by weight to 5% by weight.

The phosphoric acid ester is, for example, trimethyl phosphate and triethyl phosphate. The content of phosphoric acid ester in the non-aqueous solvent is not particularly limited, and is, for example, 0.5% by weight to 5% by weight.

A carbon-carbon triple bond chain compound is a chain compound having one or more unsaturated bonds (carbon-carbon triple bonds). Examples of such a carbon-carbon triple bond chain compound include propargyl methyl carbonate (CH≡C-CH ₂ —O—C ((O) —O—CH ₃ ) and propargyl methyl sulfonate (CH≡C—CH ₂ —O -S (= O) ₂ -CH ₃ ) and the like. The content of the chain compound having a carbon-carbon triple bond in the non-aqueous solvent is not particularly limited, and is, for example, 0.5% by weight to 5% by weight.

(Electrolyte salt)
The electrolyte salt contains, for example, any one or more of salts such as lithium salts. However, the electrolyte salt may include, for example, other salts than the lithium salt. Other salts are, for example, salts of light metals other than lithium.

The lithium salt is, for example, lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoride arsenate (LiAsF ₆ ), tetraphenyl Lithium borate (LiB (C ₆ H ₅ ) ₄ ), lithium methanesulfonate (LiCH ₃ SO ₃ ), lithium trifluoromethanesulfonate (LiCF ₃ SO ₃ ), lithium tetrachloroaluminate (LiAlCl ₄ ), hexafluoride These include dilithium silicate (Li ₂ SiF ₆ ), lithium chloride (LiCl) and lithium bromide (LiBr). This is because excellent battery capacity, cycle characteristics and storage characteristics can be obtained.

Among them, one or two or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium hexafluoroarsenate are preferable, and lithium hexafluorophosphate is more preferable. . It is because internal resistance falls.

The content of the electrolyte salt is not particularly limited, but preferably 0.3 mol / kg to 3.0 mol / kg with respect to the solvent. It is because high ion conductivity is obtained.

(Polymer compound)
The polymer compound contains one or more of homopolymers and copolymers.

Examples of homopolymers include polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, polyvinyl fluoride, polyvinyl acetate, polyvinyl alcohol, and polymethacryl. Acid methyl acrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene and polycarbonate.

The copolymer is, for example, a copolymer of vinylidene fluoride and another monomer. The “other monomer” is a monomer other than vinylidene fluoride, and is, for example, one or more of hexafluoropropylene, monomethyl maleate, trifluoroethylene, chlorotrifluoroethylene and the like. . The copolymerization amount (% by weight) of the other monomer in the copolymer is not particularly limited and can be arbitrarily set.

Among them, the homopolymer is preferably polyvinylidene fluoride, and the copolymer is preferably a copolymer of vinylidene fluoride and hexafluoropropylene. The electrolyte layer 16 is electrochemically stabilized.

Here, in the electrolyte layer 16 which is a gel electrolyte, the “solvent” contained in the electrolytic solution is not only a liquid material (the non-aqueous solvent described above) but also ion conduction capable of dissociating the electrolyte salt. It is a broad concept that includes even materials with sex. For this reason, when the polymer compound has ion conductivity, the polymer compound is also included in the solvent described herein.

(Multiple fibrous substances)
The plurality of fibrous materials include cellulose. The fiber diameter of cellulose is 40 nm or less, preferably 1 nm to 40 nm, more preferably 3 nm to 40 nm. The cellulose having a fiber diameter of 40 nm or less is so-called cellulose nanofibers. The cellulose nanofibers described here have a fiber diameter smaller than that of a cellulose fiber generally having a fiber diameter of 50 nm or more, as is apparent from the range of the fiber diameter described above.

The cellulose nanofibers are, for example, ultrafine fibers produced using so-called TEMPO oxidation. This "TEMPO oxidation" mechanically disintegrates wood fibers by causing wood fibers (pulp) to react with TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) catalyst. It is a process.

The electrolyte layer 16 contains a plurality of fibrous substances (cellulose nanofibers) because the mechanical strength of the electrolyte layer 16 is improved. As a result, the electrolyte layer 16 interposed between the positive electrode 13 and the negative electrode 14 becomes difficult to soften or flow, so the distance between the positive electrode 13 and the separator 15 becomes difficult to change, and the negative electrode 14 and the separator 15 The distance between and becomes less likely to fluctuate. Therefore, a sufficient amount of lithium ions easily and smoothly move between the positive electrode 13 and the negative electrode 14, and therefore, the discharge capacity is unlikely to decrease even if charge and discharge are repeated. In this case, particularly, even if the secondary battery is used or stored in a severe environment such as a high temperature environment, the electrolyte layer 16 does not sufficiently soften or sufficiently flow, so the discharge capacity is effectively reduced. It becomes difficult.

The average fiber length of the cellulose nanofibers is not particularly limited, but is preferably 5 μm or less, and more preferably 1 μm or less. This is because the mechanical strength of the electrolyte layer 16 is further improved. The lower limit value of the average fiber length is not particularly limited, and is, for example, 0.1 μm.

The content of the plurality of fibrous substances in the electrolyte layer 16 is not particularly limited. Among them, the ratio W2 / W1 of the weight W2 of the plurality of fibrous substances to the weight W1 of the polymer compound is preferably 0.01 to 50. Since the weights of the plurality of fibrous substances are optimized with respect to the weight of the polymer compound, the mechanical strength of the electrolyte layer 16 is further improved while maintaining the gel state in which the electrolytic solution is retained by the polymer compound. It is from.

(Additive)
The type of additive is not particularly limited. Specifically, the additive is, for example, a plurality of insulating particles. The plurality of insulating particles are dispersed in the electrolyte layer 16 in the same manner as the plurality of fibrous substances described above. The plurality of insulating particles may be held by the polymer compound.

When the electrolyte layer 16 contains a plurality of insulating particles, the separator 15 is less likely to be oxidized during charge and discharge of the secondary battery, so that a short circuit between the positive electrode 13 and the negative electrode 14 is suppressed. This improves the safety of the secondary battery.

The plurality of insulating particles include, for example, any one or more of insulating materials such as inorganic compounds. The type of inorganic compound is not particularly limited. For example, aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), magnesium oxide (MgO), aluminum nitride (AlN), boron nitride (BN) and zeolites. Zeolite includes, for example, molecular sieves and the like.

Among them, the inorganic compound is preferably aluminum oxide, aluminum nitride, boron nitride, zeolite or the like. This is because the occurrence of a short circuit is further suppressed since the separator 15 is extremely difficult to be oxidized.

The content of the plurality of insulating particles in the electrolyte layer 16 is not particularly limited. Among them, the ratio W3 / W1 of the weight W3 of the plurality of insulating particles to the weight W1 of the polymer compound is preferably 6 or less, and more preferably 0.01 to 6. Since the weights of the plurality of insulating particles are optimized with respect to the weight of the polymer compound, occurrence of a short circuit while maintaining the gel state in which the electrolyte is retained from the polymer compound and the mechanical strength of the electrolyte layer 16 Is more suppressed.

<1-2. Operation>
Next, the operation of the secondary battery will be described. The secondary battery operates, for example, as follows.

At the time of charging, lithium ions are released from the positive electrode 13 and the lithium ions are occluded by the negative electrode 14 through the electrolyte layer 16. On the other hand, at the time of discharge, lithium ions are released from the negative electrode 14, and the lithium ions are occluded by the positive electrode 13 via the electrolyte layer 16.

<1-3. Manufacturing method>
Next, a method of manufacturing a secondary battery will be described. The secondary battery provided with the gel electrolyte layer 16 is manufactured, for example, by the following three types of procedures.

[First step]
In the case of producing the positive electrode 13, first, a positive electrode active material, and if necessary, a positive electrode binder, a positive electrode conductive agent, and the like are mixed to form a positive electrode mixture. Subsequently, the positive electrode mixture is dispersed in an organic solvent or the like to prepare a paste-like positive electrode mixture slurry. Finally, the positive electrode mixture slurry is applied to both surfaces of the positive electrode current collector 13A, and then the positive electrode mixture slurry is dried to form the positive electrode active material layer 13B. After that, the positive electrode active material layer 13B may be compression molded using a roll press machine or the like, as necessary. In this case, the positive electrode active material layer 13B may be heated or compression molding may be repeated multiple times.

When manufacturing the negative electrode 14, the negative electrode active material layer 14B is formed on both surfaces of the negative electrode current collector 14A by the same procedure as the manufacturing procedure of the positive electrode 13 described above. Specifically, the negative electrode active material is mixed with a negative electrode binder and a negative electrode conductive agent to form a negative electrode mixture, and then the negative electrode mixture is dispersed in an organic solvent or the like to form a paste. A negative mix slurry is prepared. Subsequently, the negative electrode mixture slurry is applied to both surfaces of the negative electrode current collector 14A, and then the negative electrode mixture slurry is dried to form the negative electrode active material layer 14B. Thereafter, the negative electrode active material layer 14B may be compression molded using a roll press or the like, as necessary.

The method of forming the negative electrode active material layer 14B is not particularly limited. For example, any one or two or more of a coating method, a gas phase method, a liquid phase method, a thermal spraying method and a firing method (sintering method) It is. The application method is, for example, a method of applying a solution in which particles (powder) of an anode active material and an anode binder or the like are dissolved or dispersed in an organic solvent or the like to the anode current collector 14A and then drying the solution. It is. The vapor phase method is, for example, physical deposition method and chemical deposition method, and more specifically, vapor vacuum deposition method, sputtering method, ion plating method, laser ablation method, thermal chemical vapor deposition, chemical vapor phase method These include the growth (CVD) method and the plasma chemical vapor deposition method. The liquid phase method is, for example, an electrolytic plating method and an electroless plating method. The thermal spraying method is a method of spraying a molten or semi-molten negative electrode active material onto the negative electrode current collector 14A. For example, after the solution is applied to the negative electrode current collector 14A by the same procedure as the above-described application method, the temperature of the solution applied to the negative electrode current collector 14A is higher than the melting point of the negative electrode binder etc. Heat treatment. The firing method is, for example, an atmosphere firing method, a reaction firing method, a hot press firing method, or the like.

When the electrolyte layer 16 is to be formed, the electrolyte solution, the polymer compound, the plurality of fibrous substances, the organic solvent and the like are mixed, and then the mixture is stirred to prepare a precursor solution. In this case, a plurality of insulating particles may be contained in the precursor solution. The precursor solution is applied to the positive electrode 13, and then dried to form the electrolyte layer 16. The precursor solution is applied to the negative electrode 14, and then the precursor solution is dried to form the electrolyte layer 16. Form

When assembling the secondary battery, first, the positive electrode lead 11 is connected to the positive electrode current collector 13A using a welding method or the like, and the negative electrode lead 12 is connected to the negative electrode current collector 14A using a welding method or the like. . Subsequently, the positive electrode 13 on which the electrolyte layer 16 is formed and the negative electrode 14 on which the electrolyte layer 16 is formed are wound around each other through the separator 15, and then the positive electrode 13, the negative electrode 14, the separator 15, and the electrolyte layer 16. The wound electrode body 10 is formed by winding. After this, the protective tape 17 is attached to the outermost periphery of the wound electrode body 10. Subsequently, in a state in which the wound electrode body 10 is housed in the recess 20U, the exterior member 20 is folded so as to sandwich the wound electrode body 10. Finally, the outer peripheral edge portions of the exterior member 20 are adhered to each other using a heat fusion method or the like, so that the wound electrode body 10 is housed inside the exterior member 20. In this case, the adhesive film 21 is inserted between the positive electrode lead 11 and the package member 20, and the adhesive film 22 is inserted between the negative electrode lead 12 and the package member 20.

As a result, the wound electrode body 10 is enclosed in the exterior member 20, and thus the secondary battery is completed.

[Second step]
First, each of the positive electrode 13 and the negative electrode 14 is fabricated by the same procedure as the first procedure described above, and then the positive electrode lead 11 is connected to the positive electrode 13 using a welding method etc. The negative electrode lead 12 is connected to 14. Subsequently, the positive electrode 13 and the negative electrode 14 are stacked on each other through the separator 15, and then the positive electrode 13, the negative electrode 14 and the separator 31 are wound to form a wound body which is a precursor of the wound electrode body 10. Make. After this, the protective tape 37 is attached to the outermost periphery of the wound body.

Subsequently, after the exterior member 20 is folded so as to sandwich the wound electrode body 10, the remaining outer peripheral edge excluding one outer peripheral edge of the outer cover member 20 is adhered using a heat fusion method or the like. As a result, the wound body is housed inside the bag-like exterior member 20.

Subsequently, after mixing the electrolytic solution, the monomer which is the raw material of the polymer compound, a plurality of fibrous substances, the polymerization initiator and, if necessary, other materials such as the polymerization inhibitor, the mixture is The composition for electrolyte is prepared by stirring. In this case, a plurality of insulating particles may be contained in the composition for electrolyte. Subsequently, after the composition for electrolyte is injected into the inside of the bag-like exterior member 20, the exterior member 20 is sealed using a heat fusion method or the like.

Finally, a polymer compound is formed by thermally polymerizing the monomers in the composition for electrolyte. As a result, the electrolytic solution is held by the polymer compound, whereby the electrolyte layer 16 is formed. Thus, the wound electrode body 10 is sealed inside the exterior member 20.

[Third step]
First, a wound body is produced by the same procedure as the above-described second procedure except that a separator 15 in which two polymer compound layers are formed on both surfaces of a porous membrane (base material layer) is used. . Subsequently, the wound body is housed inside the bag-like exterior member 20. Subsequently, an electrolyte composition containing an electrolytic solution and a plurality of fibrous substances is injected into the inside of the package member 20, and then the opening of the package member 20 is sealed using a heat fusion method or the like. In this case, a plurality of insulating particles may be contained in the composition for electrolyte. Finally, by heating the package member 20 while applying weight to the package member 20, the separator 15 is adhered to the positive electrode 13 via the polymer compound layer, and the separator 14 is placed on the negative electrode 14 via the polymer compound layer. Attach the 15 together. Thereby, the electrolytic solution is impregnated into the polymer compound layer, and the polymer compound layer is gelated, whereby the electrolytic solution is held by the polymer compound, whereby the electrolyte layer 16 is formed. Thus, the wound electrode body 10 is sealed inside the exterior member 20.

In this third procedure, the secondary battery is less likely to swell than in the first procedure. Further, in the third procedure, compared to the second procedure, the solvent and the monomer (raw material of the polymer compound) and the like are less likely to remain in the electrolyte layer 16, so the step of forming the polymer compound is well controlled. . Thereby, each of the positive electrode 13, the negative electrode 14, and the separator 15 is sufficiently in close contact with the electrolyte layer 16.

<1-4. Action and effect>
According to this secondary battery, the electrolyte layer 16 contains a plurality of fibrous substances together with the electrolytic solution and the polymer compound, and the plurality of fibrous substances contain cellulose having a fiber diameter of 40 nm. In this case, as described above, the mechanical strength of the electrolyte layer 16 is improved, so that the distance between the positive electrode 13 and the separator 15 does not easily change, and the distance between the negative electrode 14 and the separator 15 is also It becomes difficult to change. As a result, a sufficient amount of lithium ions can be moved smoothly and stably between the positive electrode 13 and the negative electrode 14, so the discharge capacity is unlikely to be reduced even if charge and discharge are repeated. Therefore, excellent battery characteristics can be obtained.

In particular, when the ratio W2 / W1 is 0.01 to 50, the mechanical strength of the electrolyte layer 16 is further improved while maintaining the gel state in which the electrolytic solution is held by the polymer compound, so that a higher effect is obtained. be able to.

In addition, when the polymer compound contains polyvinylidene fluoride or the like, the electrolyte layer 16 is electrochemically stabilized, so that higher effects can be obtained.

In addition, if the electrolyte layer contains a plurality of insulating particles containing an inorganic compound, the safety of the secondary battery is improved, and a higher effect can be obtained. In this case, when the inorganic compound contains aluminum oxide or the like, the separator 15 becomes extremely difficult to be oxidized, so that the occurrence of a short circuit can be further suppressed, and a higher effect can be obtained. In addition, when the ratio W3 / W1 is 0.01 to 6, the occurrence of a short circuit is further suppressed while maintaining the gel-like state in which the electrolytic solution is held by the polymer compound and the mechanical strength of the electrolytic layer 16 Therefore, a higher effect can be obtained.

<2. Applications of Secondary Battery>
Next, application examples of the above-described secondary battery will be described.

Applications of secondary batteries include machines, devices, instruments, devices and systems (aggregates of multiple devices) where secondary batteries can be used as a power source for driving or a power storage source for storing electric power, etc. For example, it is not particularly limited. The secondary battery used as a power source may be a main power source or an auxiliary power source. The main power supply is a power supply that is preferentially used regardless of the presence or absence of other power supplies. The auxiliary power source may be, for example, a power source used instead of the main power source, or a power source switched from the main power source as needed. When a secondary battery is used as an auxiliary power supply, the type of main power supply is not limited to the secondary battery.

The application of the secondary battery is, for example, as follows. They are electronic devices (including portable electronic devices) such as video cameras, digital still cameras, mobile phones, laptop computers, cordless phones, headphone stereos, portable radios, portable TVs, and portable information terminals. It is a portable household appliance such as an electric shaver. Storage devices such as backup power supplies and memory cards. It is a power tool such as a power drill and a power saw. It is a battery pack installed in a notebook computer as a removable power supply. Medical electronics such as pacemakers and hearing aids. It is an electric vehicle such as an electric car (including a hybrid car). It is a power storage system such as a household battery system for storing power in preparation for an emergency or the like. Of course, applications of the secondary battery may be applications other than the above.

Among them, it is effective that the secondary battery is applied to a battery pack, an electric vehicle, an electric power storage system, an electric tool, an electronic device, and the like. Since excellent battery characteristics are required in these applications, it is possible to effectively improve the performance by using the secondary battery of the present technology. The battery pack is a power supply using a secondary battery. The battery pack may use a single cell or an assembled battery as described later. The electric vehicle is a vehicle that operates (travels) using a secondary battery as a driving power source, and as described above, may be a car (such as a hybrid car) equipped with a driving source other than the secondary battery. The power storage system is a system using a secondary battery as a power storage source. For example, in a household power storage system, since power is stored in a secondary battery which is a power storage source, it is possible to use the power to use household electrical appliances and the like. The electric power tool is a tool in which a movable portion (for example, a drill or the like) moves using a secondary battery as a power source for driving. The electronic device is a device that exhibits various functions as a power source (power supply source) for driving a secondary battery.

Here, some application examples of the secondary battery will be specifically described. The configuration of the application example described below is merely an example, and the configuration of the application example can be changed as appropriate.

<2-1. Battery pack (single cell)>
FIG. 3 shows a perspective view of a battery pack using single cells. FIG. 4 shows a block configuration of the battery pack shown in FIG. In addition, in FIG. 3, the state which the battery pack was decomposed | disassembled is shown.

The battery pack described here is a simple battery pack (so-called soft pack) using one secondary battery, and is mounted, for example, on an electronic device represented by a smartphone. For example, as shown in FIG. 3, this battery pack includes a power supply 111 which is a laminated film type secondary battery, and a circuit board 116 connected to the power supply 111. The positive electrode lead 112 and the negative electrode lead 113 are attached to the power source 111.

A pair of

adhesive tapes

118 and 119 is attached to both sides of the power supply 111. On the circuit board 116, a protection circuit (PCM: Protection Circuit) is formed. The circuit board 116 is connected to the positive electrode 112 through the tab 114 and connected to the negative electrode lead 113 through the tab 115. Further, the circuit board 116 is connected to the connector-attached lead wire 117 for external connection. When the circuit board 116 is connected to the power supply 111, the circuit board 116 is protected by the label 120 and the insulating sheet 121. By attaching the label 120, the circuit board 116, the insulating sheet 121, and the like are fixed.

The battery pack also includes, for example, a power supply 111 and a circuit board 116, as shown in FIG. The circuit board 116 includes, for example, a control unit 121, a switch unit 122, a PTC element 123, and a temperature detection unit 124. The power source 111 can be connected to the outside through the positive electrode terminal 125 and the negative electrode terminal 127, so the power source 111 is charged and discharged through the positive electrode terminal 125 and the negative electrode terminal 127. The temperature detection unit 124 detects a temperature using a temperature detection terminal (so-called T terminal) 126.

The control unit 121 controls the operation of the entire battery pack (including the usage state of the power supply 111). The control unit 121 includes, for example, a central processing unit (CPU) and a memory.

For example, when the battery voltage reaches the overcharge detection voltage, the control unit 121 disconnects the switch unit 122 so that the charging current does not flow in the current path of the power supply 111. Further, for example, when a large current flows during charging, the control unit 121 cuts off the charging current by disconnecting the switch unit 122.

On the other hand, for example, when the battery voltage reaches the overdischarge detection voltage, the control unit 121 disconnects the switch unit 122 to prevent the discharge current from flowing in the current path of the power supply 111. Further, for example, when a large current flows at the time of discharge, the control unit 121 cuts off the discharge current by disconnecting the switch unit 122.

The overcharge detection voltage is not particularly limited, but is, for example, 4.2V ± 0.05V, and the overdischarge detection voltage is not particularly limited, but is, for example, 2.4V ± 0.1 V.

The switch unit 122 switches the use state of the power supply 111, that is, the presence or absence of connection between the power supply 111 and an external device, in accordance with an instruction from the control unit 121. The switch unit 122 includes, for example, a charge control switch and a discharge control switch. Each of the charge control switch and the discharge control switch is, for example, a semiconductor switch such as a field effect transistor (MOSFET) using a metal oxide semiconductor. The charge and discharge current is detected based on, for example, the ON resistance of the switch unit 122.

The temperature detection unit 124 measures the temperature of the power supply 111 and outputs the measurement result of the temperature to the control unit 121. The temperature detection unit 124 includes, for example, a temperature detection element such as a thermistor. The measurement result of the temperature measured by the temperature detection unit 124 is used, for example, when the control unit 121 performs charge / discharge control during abnormal heat generation, or when the control unit 121 performs correction processing when calculating the remaining capacity. .

The circuit board 116 may not have the PTC element 123. In this case, the circuit board 116 may be additionally provided with a PTC element.

<2-2. Battery pack (battery pack)>
FIG. 5 shows a block configuration of a battery pack using a battery pack.

The battery pack includes, for example, a control unit 61, a power supply 62, a switch unit 63, a current measurement unit 64, a temperature detection unit 65, a voltage detection unit 66, and a switch control unit 67 in a housing 60. , A memory 68, a temperature detection element 69, a current detection resistor 70, and a positive electrode terminal 71 and a negative electrode terminal 72. The housing 60 contains, for example, a plastic material or the like.

The control unit 61 controls the operation of the entire battery pack (including the usage state of the power supply 62). The control unit 61 includes, for example, a CPU. The power source 62 is a battery pack including two or more secondary batteries, and the connection form of the two or more secondary batteries may be in series, in parallel, or a combination of both. As one example, the power supply 62 includes six secondary batteries connected in two parallel three series.

The switch unit 63 switches the use state of the power supply 62, that is, the presence or absence of connection between the power supply 62 and an external device, in accordance with an instruction from the control unit 61. The switch unit 63 includes, for example, a charge control switch, a discharge control switch, a charging diode, and a discharging diode. Each of the charge control switch and the discharge control switch is, for example, a semiconductor switch such as a field effect transistor (MOSFET) using a metal oxide semiconductor.

The current measuring unit 64 measures the current using the current detection resistor 70, and outputs the measurement result of the current to the control unit 61. The temperature detection unit 65 measures the temperature using the temperature detection element 69, and outputs the measurement result of the temperature to the control unit 61. The measurement result of the temperature is used, for example, when the control unit 61 performs charge / discharge control during abnormal heat generation, or when the control unit 61 performs correction processing when calculating the remaining capacity. The voltage detection unit 66 measures the voltage of the secondary battery in the power supply 62, and supplies the control unit 61 with the measurement result of the analog-digital converted voltage.

The switch control unit 67 controls the operation of the switch unit 63 in accordance with the signals input from each of the current measurement unit 64 and the voltage detection unit 66.

For example, when the battery voltage reaches the overcharge detection voltage, the switch control unit 67 disconnects the switch unit 63 (charge control switch) to prevent the charging current from flowing in the current path of the power supply 62. Thus, the power supply 62 can only discharge via the discharge diode. Note that, for example, when a large current flows during charging, the switch control unit 67 cuts off the charging current.

Further, for example, when the battery voltage reaches the overdischarge detection voltage, the switch control unit 67 disconnects the switch unit 63 (discharge control switch) to prevent the discharge current from flowing in the current path of the power supply 62. Thus, the power source 62 can only charge via the charging diode. The switch control unit 67 cuts off the discharge current, for example, when a large current flows during discharge.

The memory 68 includes, for example, an EEPROM which is a non-volatile memory. In the memory 68, for example, numerical values calculated by the control unit 61, information of the secondary battery measured in the manufacturing process stage (for example, internal resistance in an initial state) and the like are stored. If the full charge capacity of the secondary battery is stored in the memory 68, the control unit 61 can grasp information such as the remaining capacity.

The temperature detection element 69 measures the temperature of the power supply 62, and outputs the measurement result of the temperature to the control unit 61. The temperature detection element 69 includes, for example, a thermistor.

Each of the positive electrode terminal 71 and the negative electrode terminal 72 is used for an external device (for example, a laptop personal computer) operated by using a battery pack, an external device (for example, a charger or the like) used for charging the battery pack, It is a terminal to be connected. The power source 62 is charged and discharged via the positive electrode terminal 71 and the negative electrode terminal 72.

<2-3. Electric vehicles>
FIG. 6 shows a block configuration of a hybrid vehicle which is an example of the electric vehicle.

The electric vehicle includes, for example, a control unit 74, an engine 75, a power supply 76, a driving motor 77, a differential gear 78, a generator 79, and a transmission 80 in a metal casing 73. And a clutch 81,

inverters

82 and 83, and various sensors 84. In addition, the electric-powered vehicle includes, for example, a front wheel drive shaft 85 and a front wheel 86 connected to the differential 78 and the transmission 80, and a rear wheel drive shaft 87 and a rear wheel 88.

The electrically powered vehicle can travel, for example, using one of the engine 75 and the motor 77 as a drive source. The engine 75 is a main power source, such as a gasoline engine. When the engine 75 is used as a power source, for example, the driving force (rotational force) of the engine 75 is transmitted to the front wheels 86 and the rear wheels 88 via the differential 78 as a driving unit, the transmission 80 and the clutch 81. Ru. Since the rotational power of engine 75 is transmitted to generator 79, generator 79 generates AC power using the rotational power, and the AC power is converted to DC power through inverter 83. Therefore, the DC power is stored in the power supply 76. On the other hand, in the case where the motor 77 which is a conversion unit is used as a power source, the electric power (DC power) supplied from the power source 76 is converted into AC power via the inverter 82. 77 drives. The driving force (rotational force) converted from the electric power by the motor 77 is transmitted to the front wheel 86 and the rear wheel 88 via, for example, the differential 78 as a driving unit, the transmission 80 and the clutch 81.

When the electric vehicle decelerates via the braking mechanism, the resistance at the time of deceleration is transmitted to the motor 77 as a rotational force, so that the motor 77 generates alternating current power using the rotational force. Good. Since this AC power is converted to DC power via inverter 82, it is preferable that the DC regenerative power be stored in power supply 76.

Control unit 74 controls the operation of the entire electric vehicle. The control unit 74 includes, for example, a CPU. The power source 76 includes one or more secondary batteries. The power supply 76 may be connected to an external power supply and may store power by receiving power supply from the external power supply. The various sensors 84 are used, for example, to control the rotational speed of the engine 75 and to control the opening degree of the throttle valve (throttle opening degree). The various sensors 84 include, for example, one or more of a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

Although the case where the electric vehicle is a hybrid vehicle is exemplified, the electric vehicle may be a vehicle (electric vehicle) that operates using only the power supply 76 and the motor 77 without using the engine 75.

<2-4. Power storage system>
FIG. 7 shows a block configuration of the power storage system.

The power storage system includes, for example, a control unit 90, a power supply 91, a smart meter 92, and a power hub 93 inside a house 89 such as a home or a commercial building.

Here, the power supply 91 can be connected to, for example, the electric device 94 installed inside the house 89 and to the electric vehicle 96 stopped outside the house 89. Also, the power supply 91 is connected to, for example, a private generator 95 installed in a house 89 via a power hub 93, and is connected to an external centralized power system 97 via a smart meter 92 and the power hub 93. It is possible.

The electric device 94 includes, for example, one or more types of home appliances, and the home appliances are, for example, a refrigerator, an air conditioner, a television, a water heater, and the like. The in-house generator 95 includes, for example, one or more of a solar power generator, a wind power generator, and the like. The electric vehicle 96 includes, for example, any one or more of an electric car, an electric bike, a hybrid car and the like. The centralized power system 97 includes, for example, any one or two or more of a thermal power plant, a nuclear power plant, a hydroelectric power plant, a wind power plant and the like.

The control unit 90 controls the operation of the entire power storage system (including the usage state of the power supply 91). The control unit 90 includes, for example, a CPU. The power supply 91 includes one or more secondary batteries. The smart meter 92 is, for example, a network compatible power meter installed in the house 89 on the power demand side, and can communicate with the power supply side. Along with this, the smart meter 92 enables highly efficient and stable energy supply by controlling the balance between the demand and supply of power in the house 89 while communicating with the outside, for example.

In this power storage system, for example, power is stored in the power supply 91 from the centralized power system 97 which is an external power supply via the smart meter 92 and the power hub 93, and from a private generator 95 which is an independent power supply via the power hub 93. Thus, power is stored in the power supply 91. The electric power stored in the power supply 91 is supplied to the electric device 94 and the electric vehicle 96 according to the instruction of the control unit 90, so that the electric device 94 can be operated and the electric vehicle 96 can be charged. Become. That is, the power storage system is a system that enables storage and supply of power in the house 89 using the power supply 91.

The power stored in the power supply 91 can be used as needed. For this reason, for example, it is possible to store the power from the centralized power system 97 in the power supply 91 at midnight, when the electricity charge is low, and use the power accumulated in the power supply 91 during the day when the electricity charge is high. it can.

In addition, the above-mentioned electric power storage system may be installed for every one house (one household), and may be installed for every two or more houses (plural households).

<2-5. Power tool>
FIG. 8 shows a block configuration of the power tool.

The power tool described here is, for example, a power drill. The power tool includes, for example, a control unit 99 and a power supply 100 inside a tool body 98. For example, a drill portion 101 which is a movable portion is attached to the tool body 98 so as to be operable (rotatable).

The tool body 98 contains, for example, a plastic material or the like. The control unit 99 controls the operation of the entire power tool (including the usage state of the power supply 100). The control unit 99 includes, for example, a CPU. The power supply 100 includes one or more secondary batteries. The control unit 99 supplies power from the power supply 100 to the drill unit 101 in response to the operation of the operation switch.

Hereinafter, embodiments of the present technology will be described.

Experimental Examples 1-1 to 1-11
The laminated film type secondary battery (lithium ion secondary battery) shown in FIG. 1 and FIG. 2 was produced by the following procedure.

When producing the positive electrode 13, first, 90 parts by mass of a positive electrode active material (lithium cobaltate (LiCoO ₂ )), 5 parts by mass of a positive electrode binder (polyvinylidene fluoride), and a positive electrode conductive agent (Ketjen black) The mixture was mixed with 5 parts by mass to obtain a positive electrode mixture. Subsequently, the positive electrode mixture was charged into an organic solvent (N-methyl-2-pyrrolidone), and then the organic solvent was stirred to prepare a paste-like positive electrode mixture slurry. Subsequently, a positive electrode mixture slurry is applied on both sides of the positive electrode current collector 13A (strip-like aluminum foil, thickness = 15 μm) using a coating apparatus, and then the positive electrode mixture slurry is dried to obtain a positive electrode active material. Layer 13B was formed. Finally, the positive electrode active material layer 13B was compression molded using a roll press.

In the case of producing the negative electrode 14, first, 90 parts by weight of a negative electrode active material (artificial graphite) and 10 parts by weight of a negative electrode binder (polyvinylidene fluoride) were mixed to obtain a negative electrode mixture. Subsequently, the negative electrode mixture was charged into an organic solvent (N-methyl-2-pyrrolidone), and then the organic solvent was stirred to prepare a paste-like negative electrode mixture slurry. Subsequently, a negative electrode mixture slurry is applied on both sides of the negative electrode current collector 14A (strip-shaped copper foil, thickness = 15 μm) using a coating apparatus, and then the negative electrode mixture slurry is dried to obtain a negative electrode active material. Layer 14B was formed. Finally, the negative electrode active material layer 14B was compression molded using a roll press.

When forming the electrolyte layer 16, first, an electrolyte salt (lithium hexafluorophosphate) is added to a solvent (ethylene carbonate, propylene carbonate and ethyl methyl carbonate), and then the solvent is stirred to conduct electrolysis. The solution was prepared. In this case, the mixing ratio (weight ratio) of the solvent was ethylene carbonate: propylene carbonate: ethyl methyl carbonate = 30: 50: 60, and the concentration of the electrolyte salt was 1 mol / kg with respect to the solvent.

Subsequently, 90 parts by mass of an electrolytic solution, 10-X parts by mass of a polymer compound (copolymer of vinylidene fluoride and hexafluoropropylene, copolymerized amount of hexafluoropropylene = 15% by weight), and a plurality of fibrous A mixed solution was obtained by mixing X parts by mass of a substance (cellulose nanofiber (CNF), average fiber length = 2 μm to 3 μm) and an organic solvent for dilution (dimethyl carbonate). The types of the plurality of fibrous substances, the fiber diameter (nm), and the mixing ratio (ratio W2 / W1) of the polymer compound to the plurality of fibrous substances are as shown in Table 1.

For comparison, alumina fibers (AF, average fiber length = 2 μm to 3 μm) and cellulose fibers (CF, average fiber length = 2 μm to 3 μm) were used in place of cellulose nanofibers for comparison. . The fiber diameter (nm) and the ratio W2 / W1 are as shown in Table 1.

Subsequently, the polymer solution and the plurality of fibrous materials were uniformly dispersed in the electrolytic solution by treating the mixed solution using a homogenizer. Subsequently, the mixed solution was stirred while heating (heating temperature = 75 ° C.), and the mixed solution was further stirred (stirring time = 1 hour) to prepare a sol-like precursor solution.

Finally, the precursor solution is applied to the surface of the positive electrode 13 and then dried to form the gel electrolyte layer 16, and the precursor solution is applied to the surface of the negative electrode 14, and then the precursor solution is applied. The gel electrolyte layer 16 was formed by drying.

When assembling the secondary battery, first, the positive electrode lead 11 made of aluminum was welded to the positive electrode current collector 13A, and the negative electrode lead 12 made of copper was welded to the negative electrode current collector 14A. Subsequently, a laminate is obtained by laminating the positive electrode 13 on which the electrolyte layer 16 is formed and the negative electrode 14 on which the electrolyte layer 16 is formed via the separator 15 (microporous polyethylene film, thickness = 7 μm). I got Subsequently, the laminate was wound in the longitudinal direction, and then the protective tape 17 was attached to the outermost periphery of the laminate to produce a wound electrode body 10. Finally, after folding the exterior member 20 (outside: nylon film, thickness = 25 μm / aluminum foil, thickness = 40 μm, / polypropylene film, thickness = 30 μm: inside) so as to sandwich the wound electrode body 10, The outer peripheral edge portions of three sides of the exterior member 20 were heat-sealed. In this case, the adhesive film 21 (polypropylene film, thickness = 60 μm) is inserted between the positive electrode lead 11 and the package member 20, and the adhesive film 22 (polypropylene film) is formed between the negative electrode lead 12 and the package member 20. , Thickness = 60 μm).

As a result, since the wound electrode body 10 was sealed inside the exterior member 20, a laminate film type secondary battery was completed.

When the high temperature cycle characteristics and the low temperature cycle characteristics of the secondary battery were examined to evaluate the battery characteristics of the secondary battery, the results shown in Table 1 were obtained.

When investigating the high temperature cycle characteristics, first, in order to stabilize the state of the secondary battery, the secondary battery was charged and discharged in a normal temperature environment (temperature = 25 ° C.). Subsequently, the discharge capacity in the second cycle was measured by charging and discharging the secondary battery in a high temperature environment (temperature = 45 ° C.). Subsequently, the discharge capacity of the 100th cycle was measured by repeatedly charging and discharging the secondary battery until the number of charge and discharge cycles reaches 100 cycles in the same environment. Finally, the high temperature capacity retention ratio (%) = (discharge capacity at 100th cycle / discharge capacity at second cycle) × 100 was calculated.

At the time of charge, constant current charge is performed until the voltage reaches 4.35 V at a current density of 1 mA / cm ² and then constant voltage charge until the current density reaches 0.02 mA / cm ² at a voltage of 4.35 V did. During the discharge, the battery was discharged at a current density of 1 mA / cm ² until the voltage reached 3 V.

When investigating the low-temperature cycle characteristics, follow the same procedure as when investigating the high-temperature cycle characteristics except that the secondary battery is charged and discharged in the low-temperature environment (temperature = 0 ° C.) instead of in the high-temperature environment. Low temperature capacity retention ratio (%) = (discharge capacity at 100th cycle / discharge capacity at second cycle) × 100 was calculated.

Each of the high temperature capacity retention rate and the low temperature capacity retention rate varied greatly depending on the types and configurations of the plurality of fibrous materials. Hereinafter, the high temperature capacity retention ratio and the low temperature capacity retention ratio in the case where the electrolyte layer 16 does not contain a plurality of fibrous substances (Experimental Example 1-8) are used as comparison standards.

Specifically, when alumina fibers or cellulose fibers are used as a plurality of fibrous substances (Examples 1-9 and 1-10), the high temperature capacity retention rate and the low temperature capacity retention rate respectively increase only slightly. It was not. Specifically, when the alumina fiber was used, the increase rate of the high temperature capacity retention rate was about 6.7%, and the increase rate of the low temperature capacity retention rate was about 6.7%. In addition, when the cellulose fiber was used, the increase rate of the high temperature capacity retention rate was about 3.3%, and the increase rate of the low temperature capacity retention rate was about 6.7%.

On the other hand, when cellulose nanofibers were used as a plurality of fibrous substances, the high temperature capacity retention ratio and the low temperature capacity retention ratio dramatically changed according to the fiber diameter of the cellulose nanofibers.

That is, when the average fiber diameter of the cellulose nanofibers was larger than 40 nm (Experimental Example 1-11), each of the high temperature capacity retention rate and the low temperature capacity retention rate decreased significantly. However, when the fiber diameter of the cellulose nanofibers is 40 nm or less (Experimental Examples 1-1 to 1-7), each of the high temperature capacity retention rate and the low temperature capacity retention rate significantly increases. Specifically, the increase rate of the high temperature capacity retention rate is about 33.3% at the minimum and about 103.3% at the maximum, and the increase rate of the low temperature capacity retention rate is about 26.7% at the minimum The maximum was about 113.3%.

In particular, when cellulose nanofibers having a fiber diameter of 40 nm or less were used, when the ratio W2 / W1 was 0.01 to 50, the high temperature capacity retention rate and the low temperature capacity retention rate were further increased.

(Experimental examples 2-1 to 2-8)
As shown in Table 2, the same as Experimental Example 1-1 except that the electrolyte layer 16 contained a plurality of insulating particles (aluminum oxide (Al ₂ O ₃ , median diameter D 50 = 0.3 μm)). The secondary battery was fabricated and the battery characteristics were examined according to the following procedure.

When preparing a mixed solution, 90 parts by mass of electrolyte solution, 10 parts by mass of polymer compound, X parts by mass of a plurality of fibrous substances, Y parts by mass of a plurality of insulating particles, and for dilution And an organic solvent (dimethyl carbonate). The mixing ratio (ratio W3 / W1) of the polymer compound to the plurality of insulating particles is as shown in Table 2.

When the electrolyte layer 16 contains a plurality of insulating particles (Experimental Examples 2-1 to 2-8), the case where the electrolyte layer 16 does not contain a plurality of insulating particles (Experimental Example 1-1) In comparison, each of the high temperature capacity retention rate and the low temperature capacity retention rate increased.

In particular, when a plurality of insulating particles are used, when the ratio W3 / W1 is 0.01 to 6 (Experimental Examples 2-1 to 2-5), the high temperature capacity retention ratio and the low temperature capacity retention ratio are each Increased more.

From the results shown in Tables 1 and 2, when the electrolyte layer contains a plurality of fibrous materials (cellulose having a fiber diameter of 40 nm or less) together with the electrolytic solution and the polymer compound, high temperature cycle characteristics and low temperature cycle characteristics are obtained. Both have been improved. Therefore, excellent battery characteristics were obtained in the secondary battery.

Although the present technology has been described above by citing embodiments and examples, the present technology is not limited to the aspects described in the embodiments and examples, and various modifications are possible.

Specifically, although the laminated film type secondary battery has been described, the present invention is not limited to this. For example, a cylindrical secondary battery, a square secondary battery, and a coin secondary battery may be used.

Although the case where the battery element has a wound structure has been described, the present invention is not limited to this. For example, the battery element may have another structure such as a laminated structure.

In addition, although the lithium ion secondary battery in which the capacity of the negative electrode is obtained by utilizing the lithium storage phenomenon and the lithium release phenomenon has been described, the invention is not limited thereto. For example, it may be a lithium ion secondary battery in which the capacity of the negative electrode is obtained by utilizing the precipitation phenomenon of lithium and the dissolution phenomenon of lithium. Also, for example, by setting the capacity of the negative electrode active material capable of inserting and extracting lithium to be smaller than the capacity of the positive electrode, the capacity resulting from the lithium absorption phenomenon and the lithium release phenomenon and the lithium It may be a secondary battery in which the capacity of the negative electrode is obtained based on the sum of the capacity resulting from the deposition phenomenon and the dissolution phenomenon of lithium.

Moreover, although demonstrated regarding the secondary battery which used lithium as an electrode reaction substance, it is not restricted to this. For example, sodium and potassium may be any other Group 1 element in any long period periodic table, or may be elements of Group 2 in the long periodic table such as magnesium and calcium, or other light metals such as aluminum.

In addition, the effect described in this specification is an illustration to the last, is not limited, and may have other effects.

The present technology can also be configured as follows.
(1)
Positive electrode,
A negative electrode,
(A) an electrolytic solution, a polymer compound, and a plurality of fibrous substances, (B) the electrolytic solution is held by the polymer compound, and (C) the plurality of fibrous substances are And an electrolyte layer comprising cellulose having a fiber diameter of 40 nm or less.
(2)
The ratio of the weight of the plurality of fibrous substances to the weight of the polymer compound is 0.01 or more and 50 or less.
The secondary battery as described in said (1).
(3)
The polymer compound includes at least one of polyvinylidene fluoride and a copolymer of vinylidene fluoride and hexafluoropyrene.
The secondary battery as described in said (1) or (2).
(4)
The electrolyte layer further includes a plurality of insulating particles containing an inorganic compound.
The secondary battery according to any one of the above (1) to (3).
(5)
The inorganic compound includes at least one of aluminum oxide, aluminum nitride, boron nitride and zeolite.
The secondary battery as described in said (4).
(6)
The ratio of the weight of the plurality of insulating particles to the weight of the polymer compound is 0.01 or more and 6 or less.
The secondary battery as described in said (4) or (5).
(7)
Being a lithium ion secondary battery,
The secondary battery according to any one of the above (1) to (6).
(8)
The secondary battery according to any one of the above (1) to (7);
A control unit that controls the operation of the secondary battery;
A switch unit that switches the operation of the secondary battery according to an instruction of the control unit.
(9)
The secondary battery according to any one of the above (1) to (7);
A converter for converting the power supplied from the secondary battery into a driving power;
A driving unit driven according to the driving force;
And a control unit that controls the operation of the secondary battery.
(10)
The secondary battery according to any one of the above (1) to (7);
One or more electric devices supplied with power from the secondary battery,
And a controller configured to control power supply from the secondary battery to the electric device.
(11)
The secondary battery according to any one of the above (1) to (7);
A movable part to which power is supplied from the secondary battery;
(12)
The electronic device provided with the secondary battery in any one of said (1) thru | or (7) as an electric power supply source.

Claims

Positive electrode,
A negative electrode,
(A) an electrolytic solution, a polymer compound, and a plurality of fibrous substances, (B) the electrolytic solution is held by the polymer compound, and (C) the plurality of fibrous substances are And an electrolyte layer comprising cellulose having a fiber diameter of 40 nm or less.
The ratio of the weight of the plurality of fibrous substances to the weight of the polymer compound is 0.01 or more and 50 or less.
The secondary battery according to claim 1.
The polymer compound includes at least one of polyvinylidene fluoride and a copolymer of vinylidene fluoride and hexafluoropyrene.
The secondary battery according to claim 1.
The electrolyte layer further includes a plurality of insulating particles containing an inorganic compound.
The secondary battery according to claim 1.
The inorganic compound includes at least one of aluminum oxide, aluminum nitride, boron nitride and zeolite.
The secondary battery according to claim 4.
The ratio of the weight of the plurality of insulating particles to the weight of the polymer compound is 0.01 or more and 6 or less.
The secondary battery according to claim 4.
Being a lithium ion secondary battery,
The secondary battery according to claim 1.
With a secondary battery,
A control unit that controls the operation of the secondary battery;
A switch unit that switches the operation of the secondary battery in accordance with an instruction from the control unit;
The secondary battery is
Positive electrode,
A negative electrode,
(A) an electrolytic solution, a polymer compound, and a plurality of fibrous substances, (B) the electrolytic solution is held by the polymer compound, and (C) the plurality of fibrous substances are An electrolyte layer comprising cellulose having a fiber diameter of 40 nm or less.
With a secondary battery,
A converter for converting the power supplied from the secondary battery into a driving power;
A driving unit driven according to the driving force;
A control unit that controls the operation of the secondary battery;
The secondary battery is
Positive electrode,
A negative electrode,
(A) an electrolytic solution, a polymer compound, and a plurality of fibrous substances, (B) the electrolytic solution is held by the polymer compound, and (C) the plurality of fibrous substances are And an electrolyte layer comprising cellulose having a fiber diameter of 40 nm or less.
With a secondary battery,
One or more electric devices supplied with power from the secondary battery,
A control unit that controls power supply from the secondary battery to the electric device;
The secondary battery is
Positive electrode,
A negative electrode,
(A) an electrolytic solution, a polymer compound, and a plurality of fibrous substances, (B) the electrolytic solution is held by the polymer compound, and (C) the plurality of fibrous substances are And an electrolyte layer comprising cellulose having a fiber diameter of 40 nm or less.
With a secondary battery,
A movable part supplied with power from the secondary battery;
The secondary battery is
Positive electrode,
A negative electrode,
(A) an electrolytic solution, a polymer compound, and a plurality of fibrous substances, (B) the electrolytic solution is held by the polymer compound, and (C) the plurality of fibrous substances are And an electrolyte layer comprising cellulose having a fiber diameter of 40 nm or less.
Equipped with a secondary battery as a power supply source,
The secondary battery is
Positive electrode,
A negative electrode,
(A) an electrolytic solution, a polymer compound, and a plurality of fibrous substances, (B) the electrolytic solution is held by the polymer compound, and (C) the plurality of fibrous substances are And an electrolyte layer comprising cellulose having a fiber diameter of 40 nm or less.