WO2017168982A1

WO2017168982A1 - Secondary battery negative electrode, secondary battery, battery pack, electric vehicle, power storage system, electric tool and electronic device

Info

Publication number: WO2017168982A1
Application number: PCT/JP2017/001838
Authority: WO
Inventors: 中村　利一; 松本　健
Original assignee: ソニー株式会社
Priority date: 2016-03-31
Filing date: 2017-01-20
Publication date: 2017-10-05

Abstract

A secondary battery negative electrode is provided which can achieve excellent battery characteristics. This secondary battery negative electrode contains a negative electrode active material powder, a coating layer formed on the negative electrode active material powder, and a binding agent, wherein the coating layer contains a hydrocarbon polymer which contains at least one item selected from the group consisting of ether bonds, carbonyl groups, carboxylic acid, carboxylic acid salts, carbonic acid and carbonic acid salts.

Description

Negative electrode for secondary battery, secondary battery, battery pack, electric vehicle, power storage system, electric tool and electronic device

This technology relates to a negative electrode for a secondary battery and a secondary battery. More specifically, the present technology relates to a negative electrode for a secondary battery, a secondary battery, a battery pack, an electric vehicle, an electric power storage system, an electric tool, and an electronic device.

In recent years, portable electronic devices such as video cameras, digital still cameras, mobile phones, and notebook computers have become widespread, and their miniaturization, weight reduction, and long life have been strongly demanded. Along with this, development of batteries as power sources, particularly secondary batteries that are small and lightweight and capable of obtaining a high energy density, is underway.

In particular, lithium ion secondary batteries that use the insertion and release of lithium ions as charge / discharge reactions and lithium metal secondary batteries that use lithium metal precipitation and dissolution are highly expected. This is because an energy density higher than that of the lead battery and the nickel cadmium battery can be obtained.

Recently, since the advantages of light weight and high energy density are suitable for automobile applications such as electric vehicles and hybrid electric vehicles, research aimed at increasing the size and output of secondary batteries has been actively conducted. Yes.

For example, a carbon material for a non-aqueous electrolyte secondary battery in which two or more polymer layers are laminated on a carbon material (A), and a layer made of a composition containing at least a water-soluble polymer (B) and a water-insoluble solution A carbon material (D) for a non-aqueous electrolyte secondary battery in which layers made of a composition containing a conductive polymer (C) are sequentially laminated has been proposed (see Patent Document 1). According to the technique proposed in Patent Document 1, it is possible to provide a non-aqueous electrolyte secondary battery with a high capacity and a small amount of gas generation.

Japanese Patent No. 5540826

However, in the present technical field, a secondary battery with improved battery characteristics is desired more than the secondary battery based on the technique proposed in Patent Document 1.

Therefore, the present technology has been made in view of such a situation, and a negative electrode for a secondary battery that can contribute to excellent battery characteristics, a secondary battery having excellent battery characteristics, and the secondary battery. A battery pack, an electric vehicle, an electric power storage system, an electric tool, and an electronic device.

As a result of intensive studies to solve the above-mentioned object, the present inventors have surprisingly succeeded in dramatically improving battery characteristics by providing a coating layer on the secondary battery negative electrode. And this technology was completed.

That is, the present technology includes a negative electrode active material powder, a coating layer formed on the negative electrode active material powder, and a binder, and the coating layer includes an ether bond, a carbonyl group, a carboxylic acid, Provided is a negative electrode for a secondary battery comprising a hydrocarbon polymer containing at least one selected from the group consisting of carboxylate, carbonate and carbonate.

The coating layer is a component formed by heat-treating a carboxymethylcellulose-based water-soluble polymer, a component formed by heat-treating a polyacrylic acid-based water-soluble polymer, and a methacrylic acid-based water-soluble polymer Thus, at least one selected from the group consisting of components formed may be included.
The coating layer may include at least one selected from the group consisting of a carboxymethylcellulose-based water-soluble polymer, a polyacrylic acid-based water-soluble polymer, and a methacrylic acid-based water-soluble polymer.
The coating layer may include at least one selected from the group consisting of fibrous carbon, vapor grown carbon fiber, carbon nanotube, graphene, and powdered carbon.
The coating layer may include a carboxylic acid and / or a carboxylate.
The carboxylate may be sodium oxalate or lithium oxalate.

The binder may be included in the coating layer. The binder may be a polyvinylidene fluoride polymer.

The negative electrode active material powder may contain a carbon-based material and / or a silicon-based material.

The negative electrode for a secondary battery may contain N-methylpyrrolidone.

Further, the present technology includes at least a negative electrode for a secondary battery, a positive electrode for a secondary battery, and an electrolytic solution, and the negative electrode for a secondary battery includes a negative electrode active material powder and a negative electrode active material powder on the negative electrode active material powder. A coating layer and a binder, and the coating layer contains at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate, and a carbonate. A secondary battery including a hydrocarbon polymer is provided.

In the present technology, a secondary battery according to the present technology, a control unit that controls a usage state of the secondary battery, and a switch unit that switches a usage state of the multivalent ion secondary battery according to an instruction of the control unit, A battery pack is provided.
Further, in the present technology, the secondary battery according to the present technology, a conversion unit that converts electric power supplied from the secondary battery into a driving force, a driving unit that is driven according to the driving force, and the secondary battery An electric vehicle comprising: a control unit that controls a use state of the vehicle.
Furthermore, in the present technology, the secondary battery according to the present technology, one or more electric devices to which electric power is supplied from the secondary battery, and control for controlling power supply from the secondary battery to the electric device And a power storage system comprising: a unit.

The present technology provides an electric tool including a secondary battery according to the present technology and a movable part to which electric power is supplied from the secondary battery.
In addition, the present technology provides an electronic device including the secondary battery according to the present technology as a power supply source.

According to the present technology, the battery characteristics can be improved. In addition, the effect described here is not necessarily limited, and may be any effect described in the present technology.

It is sectional drawing showing the structure of the example (cylindrical type) of the secondary battery which concerns on this technique. It is a figure which expands and represents a part of winding electrode body shown in FIG. It is a perspective view showing the composition of the example (lamination film type) of the secondary battery concerning this art. FIG. 4 is a cross-sectional view taken along line IV-IV of the spirally wound electrode body illustrated in FIG. 3. It is a block diagram showing the structure of the application example (battery pack) of the secondary battery which concerns on this technique. It is a block diagram showing the structure of the application example (electric vehicle) of the secondary battery which concerns on this technique. It is a block diagram showing the structure of the application example (electric power storage system) of the secondary battery which concerns on this technique. It is a block diagram showing the structure of the application example (electric tool) of the secondary battery which concerns on this technique. It is a figure which shows the relationship between the capacity | capacitance maintenance factor (%) and the number of cycles (times) regarding Examples 1 and 3 and Comparative Example 1.

Hereinafter, preferred embodiments for implementing the present technology will be described. The embodiment described below shows an example of a typical embodiment of the present technology, and the scope of the present technology is not interpreted narrowly.

The description will be given in the following order.
1. Overview of this technology First embodiment (negative electrode for secondary battery)
3. Second embodiment (secondary battery)
4). Example of secondary battery 4-1. Secondary battery example (cylindrical lithium ion secondary battery)
4-2. Secondary battery example (laminate film type lithium ion secondary battery)
5. Applications of secondary batteries 5-1. Overview of secondary battery applications 5-2. Third embodiment (battery pack)
5-3. Fourth embodiment (electric vehicle)
5-4. Fifth embodiment (power storage system)
5-5. Sixth embodiment (power tool)
5-6. Seventh embodiment (electronic device)

<1. Overview of this technology>
First, an outline of the present technology will be described.
Regarding carbon materials used in lithium ion secondary batteries having an active material capable of occluding or releasing lithium ions, which is one of the secondary batteries, in the case of graphite having a high degree of crystallinity or high degree of graphitization, at the first charge and at a high temperature The amount of gas generated during storage tends to increase. One reason is that the solid-liquid interface (SEI) coating (hereinafter referred to as coating) formed during charging has low co-insertion resistance to an electrolyte solvent, particularly propylene carbonate (hereinafter referred to as PC). Because it breaks or flows out, the degree of film re-formation increases during charge / discharge cycles and during high-temperature storage, and the amount of solvent that undergoes reductive decomposition increases, resulting in an increase in the amount of generated gas or lithium precipitation. In addition, the charge / discharge efficiency is lowered and the low temperature characteristics are lowered. In the case of a laminate type secondary battery cell, there are also concerns about appearance such as cell swelling.

Therefore, as a guideline for countermeasures, a method has been established in which the negative electrode carbon is covered with amorphous carbon (pitch coating) to control side reactions such as gas generation.

However, since pitch coating reduces the ionic conductivity on the surface of the active material, it is considered that there is a trade-off relationship between the load characteristics and the low-temperature characteristics. In addition, when a boron salt is contained in the pitch coat, the charge / discharge efficiency is improved as compared with a pitch coat not containing boron, but the improvement effect is particularly effective when the cell voltage at which lithium is liable to precipitate is 4.35V. Seems to be quite limited.

In addition, a technology related to negative electrode active materials and current collectors related to water-based paint electrodes (water / CMC / SBR negative electrode), including two types of polymers that are well-soluble and poorly-soluble in electrolytes. There is.

In this technique, two kinds of water-soluble polymers with good and poor electrolyte swell (for example, CMC + water-insoluble polymer (SBR) included) are dry-adhered or powder-mixed to the active material powder, and the subsequent water CMC paint Improvement of charge / discharge efficiency by improving current collecting performance by improving adhesion strength (peeling strength) between a certain mixture and current collector foil or improving electrolyte penetration by improving electrolyte wettability There is a possibility to make it.

However, there are concerns about rapid deterioration due to the generation of hydrogen gas during the initial charge due to decomposition of residual water or residual OH groups, and deterioration of the mixture separation current collection due to charge / discharge expansion / contraction, which may occur because of the water-based negative electrode. In this regard, the N-methylpyrrolidone (NMP) -polyvinylidene fluoride polymer (PVDF) system is considered to be better.

Also, for example, the formation of SEI film by ethylene carbonate (EC) reduction reaction that occurs well when the negative electrode potential is in the vicinity of 0.9 V to 0.6 V vs. Li depends on the impregnation state of the electrolyte in the active material mixture layer. The surface layer of active material agglomerates in the surface layer has a high density and a low density in the back layer. Problems such as swelling of the electrode mixture layer due to co-insertion of the solvent into the active material layer under low-temperature discharge and Li precipitation due to film destruction Cause.

Furthermore, when SiO is contained in the negative electrode, when the rise in negative electrode potential during discharge reaches 0.7 V vs. Li or more, the silicate (Li—O—Li) itself of the SiO surface layer decomposes and dissolves, so that as the SiO active material The surface of the SEI that has already been formed and the exposed surface of the SEI that has already been formed are re-formed and increased by a reductive reaction in the subsequent charging, thereby promoting the expansion of the active material itself. This leads to a problem that the current cannot be collected, that is, rapid deterioration of cycle characteristics.

The present technology is based on the above situation, and the present technology includes a negative electrode active material powder, a coating layer formed on the negative electrode active material powder, and a binder, Excellent battery characteristics by using a negative electrode for a secondary battery comprising a hydrocarbon polymer containing at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonic acid and a carbonate In particular, it can contribute to excellent cycle characteristics.

The present technology also includes at least a negative electrode for a secondary battery, a positive electrode for a secondary battery, and an electrolyte, and the negative electrode for a secondary battery is formed on the negative electrode active material powder and the negative electrode active material powder. A hydrocarbon layer containing a coating layer and a binder, wherein the coating layer contains at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate, and a carbonate. By using a secondary battery including a product, excellent battery characteristics, in particular, excellent cycle characteristics can be obtained.

<2. First Embodiment (Anode for Secondary Battery)>
[Anode for secondary battery]
The negative electrode for a secondary battery according to the first embodiment of the present technology includes a negative electrode active material powder, a coating layer formed on the negative electrode active material powder, and a binder, A negative electrode for a secondary battery, comprising a hydrocarbon polymer containing at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonic acid and a carbonate.

The secondary battery negative electrode of the first embodiment according to the present technology contributes to excellent battery characteristics, and in particular, can contribute to improvement of cycle characteristics. That is, according to the negative electrode for secondary battery of the first embodiment according to the present technology, hydrogen gas generation at the initial charge due to residual water or residual OH group decomposition, which is a problem because it is a water-based paint negative electrode, Thus, it is possible to greatly improve the point of concern about rapid deterioration of the cycle due to a decrease in the performance of collecting and separating the current accompanying charge / discharge expansion and contraction. By using the negative electrode for a secondary battery according to the first embodiment of the present technology, side reaction such as gas generation due to side reaction with a reaction active site on the carbon surface by the coating layer, ion conductivity improvement, mechanical In addition, the improvement in electrochemical stability and the like can contribute to a favorable improvement effect in the charge / discharge cycle characteristics of the secondary battery.

[Negative electrode active material powder]
The negative electrode active material powder included in the secondary battery negative electrode of the first embodiment according to the present technology is not particularly limited and may be any negative electrode active material powder, but may be a carbon material, a silicon-based material, or a carbon material. A mixture of a silicon-based material is preferred. This preferred embodiment can contribute to improvement of battery characteristics, particularly cycle characteristics.

[Carbon-based materials]
Since the carbon material undergoes very little change in the crystal structure during insertion and extraction of Li, a high energy density and excellent cycle characteristics can be obtained. The carbon material can also function as a negative electrode conductive agent. Examples of the carbon material include graphitizable carbon, non-graphitizable carbon, and graphite. However, the interplanar spacing of the (002) plane in non-graphitizable carbon is preferably 0.37 nm or more, and the interplanar spacing of the (002) plane in graphite is preferably 0.34 nm or less. More specifically, pyrolytic carbons, cokes, glassy carbon fibers, organic polymer compound fired bodies, activated carbon and carbon blacks. The cokes include pitch coke, needle coke and petroleum coke. The organic polymer compound fired body is obtained by firing (carbonizing) a polymer compound such as a phenol resin and a furan resin at an appropriate temperature. In addition, the carbon material may be low crystalline carbon heat-treated at a temperature of about 1000 ° C. or less, or may be amorphous carbon. The shape of the carbon material may be any of a fibrous shape, a spherical shape, a granular shape, and a scale shape.

[Silicon material]
The silicon-based material may be any of a simple substance of Si (silicon), an alloy and a compound (silicon oxide, silicon fluoride, etc.), two or more of them, and one or two or more phases thereof. May be at least partially included. The simple substance is a simple substance in a general sense (may contain a small amount of impurities), and does not necessarily mean 100% purity.

The alloy of Si is, for example, any one or two of Sn, Ni, Cu, Fe, Co, Mn, Zn, In, Ag, Ti, Ge, Bi, Sb and Cr as constituent elements other than Si. It contains the above elements. The Si compound includes, for example, one or more of C, O, F and the like as a constituent element other than Si. Note that the Si compound may include, for example, any one or more of the elements described with respect to the Si alloy as a constituent element other than Si.

Si alloys and compounds include, for example, SiB ₄ , SiB ₆ , Li ₂ SiF ₆ , Mg ₂ Si, Ni ₂ Si, TiSi 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, SiOv (0 <v ≦ 2), and LiSiO the like. Note that v in SiOv may be 0.2 <v <1.4.

[Mixed material of carbon material and silicon material]
The mixed material of the carbon material and the silicon-based material is more preferably a mixture of graphite and SiO. The mass ratio of the mixture of the carbon material and the silicon-based material may be any ratio, but is preferably a ratio of 100: 0 to 85:15, and a ratio of 95: 5 to 90:10 More preferred.

The negative electrode active material powder other than the carbon material, the silicon-based material, and the mixture of the carbon material and the silicon-based material is a material including any one or two 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 of a simple substance, an alloy, and a compound, or two or more kinds thereof, or one having at least a part of one or two or more phases thereof. The alloy includes a material including one or more metal elements and one or more metalloid elements in addition to a material composed of two or more metal elements. The alloy may contain a nonmetallic element. The structure includes a solid solution, a eutectic (eutectic mixture), an intermetallic compound, and two or more kinds of coexisting substances.

The metal element and metalloid element described above are, for example, one or more metal elements and metalloid elements capable of forming an alloy with Li. Specifically, for example, Mg, B, Al, Ga, In, Ge, Sn, Pb, Bi, Cd, Ag, Zn, Hf, Zr, Y, Pd, and Pt.

[Coating layer]
The coating layer included in the secondary battery negative electrode according to the first embodiment of the present technology is formed on the negative electrode active material powder. The coating layer is formed on the negative electrode active material powder. The coating layer may be formed on the entire surface of the negative electrode active material powder, or may be formed on at least a part of the surface of the negative electrode active material powder. Means good. In addition, as long as the coating layer is formed on the entire surface of the negative electrode active material powder or at least a part of the surface, the coating layer may penetrate into the negative electrode active material powder.

The coating layer includes a hydrocarbon polymer containing at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate, and a carbonate.

The hydrocarbon polymer may be any hydrocarbon polymer as long as it contains at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate and a carbonate.

The coating layer heat-treats a component formed by heat-treating a carboxymethylcellulose-based water-soluble polymer, a component formed by heat-treating a polyacrylic acid-based water-soluble polymer, and a methacrylic acid-based water-soluble polymer. It is preferable to include at least one selected from the group consisting of components formed by the above. Components formed by heat-treating carboxymethylcellulose-based water-soluble polymer, components formed by heat-treating polyacrylic acid-based water-soluble polymer, and formed by heat-treating methacrylic acid-based water-soluble polymer Each of the components includes a hydrocarbon polymer containing at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, and a carboxylate.

The coating layer preferably contains at least one selected from the group consisting of carboxymethylcellulose-based water-soluble polymers, polyacrylic acid-based water-soluble polymers, and methacrylic acid-based water-soluble polymers.

Examples of the carboxymethylcellulose-based water-soluble polymer include carboxymethylcellulose acid, carboxymethylcellulose sodium salt, carboxymethylcellulose lithium salt, carboxymethylcellulose ammonium salt, and the like. It is a modified water-soluble polymer. Carboxymethylcellulose-based water-soluble polymer is subjected to a heat treatment to oxalic acid or oxalate (sodium salt, lithium salt), carbonate (sodium salt, lithium salt), hydrocarbon polymer containing carbonyl group, etc. Become.

Examples of the polyacrylic acid-based water-soluble polymer include polyacrylic acid, sodium polyacrylate, lithium polyacrylate, ammonium polyacrylate, and the like. A water-soluble polymer modified with lithium, ammonium or the like. The polyacrylic acid-based water-soluble polymer is subjected to a heat treatment to become a hydrocarbon polymer containing a carbonate (sodium salt, lithium salt), a carbonyl group, an acrylic group, or the like.

Examples of the methacrylic acid-based water-soluble polymer include methacrylic acid, methyl methacrylate, ethyl methacrylate and the like, and are water-soluble polymers in which methacrylic acid itself or a part of methacrylic acid is modified with sodium or lithium. . The methacrylic acid-based water-soluble polymer is subjected to a heat treatment to become a hydrocarbon polymer containing carbonate (sodium salt, lithium salt), carbonyl group or the like.

In addition, the coating layer preferably contains at least one selected from the group consisting of fibrous carbon, vapor grown carbon fiber, carbon nanotube, graphene, and powdered carbon. Fibrous carbon and powdered carbon are preferably conductive.

Furthermore, the coating layer preferably contains carboxylic acid, carboxylate, a mixture of carboxylic acid and carboxylate, carbonic acid, carbonate or a mixture of carbonic acid and carbonate. According to this preferred embodiment, ion conductivity can be improved, and an improvement effect in further charge / discharge cycle characteristics can be obtained.

The carboxylic acid is not particularly limited, but is preferably oxalic acid. The carboxylate is not particularly limited, and examples thereof include sodium oxalate, lithium oxalate, and ammonium oxalate, and sodium oxalate or lithium oxalate is preferable. The carbonate is not particularly limited but is preferably sodium carbonate or lithium carbonate.

The coating layer is obtained by mixing a hydrocarbon polymer containing at least one selected from the group consisting of ether bonds, carbonyl groups, carboxylic acids, carboxylates, carbonates and carbonates, negative electrode active material powders, etc. It can be obtained by drying and heat-treating in a paint state, pulverizing, sizing and forming. The heat treatment is preferably performed in a high temperature atmosphere of 180 ° C. or higher and 350 ° C. or lower.

To reduce functional groups and reaction points related to side reactions by reacting or coating the coating layer with reactive active sites on the negative electrode surface (for example, hydroxyl groups on the carbon surface or Cδ- (delta minus) points on the carbon). Moreover, the side effect of hydrogen gas generation | occurrence | production at the time of first charge, the improvement effect of the tolerance with respect to the malfunction by propylene carbonate (PC), such as propylene carbonate (PC) co-insertion, is seen.

Since the coating layer is obtained by heat treatment, it has ionic conductivity, so it has a function as a pseudo solid-liquid interface (SEI) coating, is electrochemically stable, and has a physical mechanical strength, for example, Since it is stable against heat (heating) of about 40 ° C. to 90 ° C., it is less likely to break down or flow out, and exhibits good characteristics even under test conditions such as high temperature storage and high temperature cycling of the cell.

[Binder]
The negative electrode for secondary batteries of the first embodiment according to the present technology includes a binder. Although a binder is not specifically limited, For example, any 1 type or 2 types or more, such as a synthetic rubber and a polymeric material, are included. Examples of the synthetic rubber include styrene butadiene rubber, fluorine rubber, and ethylene propylene diene. Examples of the polymer material include polyvinylidene fluoride and polyimide. A polyvinylidene fluoride polymer (PVDF) ) Is preferred.

The binder is preferably contained inside the coating layer. The coating layer containing the binder in the coating layer includes a hydrocarbon polymer containing at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate and a carbonate, a binder. It can be obtained by forming a powder, a negative electrode active material powder, etc., by drying and heat-treating them in a powder mixed or paint state, pulverizing and sizing.

The secondary battery negative electrode according to the first embodiment of the present technology preferably includes N-methylpyrrolidone (NMP). When forming a coating layer on the negative electrode active material powder to form a coating material, a binder, particularly N-methylpyrrolidone (NMP) having solubility of a polyvinylidene fluoride polymer can be used. In the case of coating with a non-aqueous solvent, there is no influence of residual water, and the high binding property of the binder, especially polyvinylidene fluoride polymer (PVDF), and the characteristics as a binder, the combination with charge / discharge expansion / contraction The agent peeling current collection performance does not drop rapidly, and problems such as rapid cycle deterioration do not occur. This effect is particularly remarkable in an active material composition containing a silicon-based material in addition to a carbon-based material.

<3. Second Embodiment (Secondary Battery)>
[Secondary battery]
A secondary battery according to a second embodiment of the present technology includes at least a negative electrode for a secondary battery, a positive electrode for a secondary battery, and an electrolytic solution, and the negative electrode for a secondary battery includes a negative electrode active material powder and A coating layer formed on the negative electrode active material powder, and a binder, the coating layer comprising an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate, and a carbonate. It is a secondary battery including a hydrocarbon polymer containing at least one selected.

According to the secondary battery of the second embodiment according to the present technology, excellent battery characteristics can be obtained, and in particular, excellent cycle characteristics can be obtained. That is, according to the secondary battery of the first embodiment of the present technology, the problem is that the negative electrode is a water-based paint-formed negative electrode. Significant improvements can be made with respect to concerns about rapid cycle deterioration due to a decrease in the performance of collecting and releasing current accompanying discharge expansion and contraction. By using the secondary battery of the second embodiment according to the present technology, side reaction such as gas generation due to side reaction with the reactive surface of the carbon surface by the coating layer is suppressed, ion conductivity is improved, mechanical and electrical By improving the chemical stability and the like, it is possible to obtain a favorable improvement effect in the charge / discharge cycle characteristics of the secondary battery.

[Anode for secondary battery]
The negative electrode for secondary battery provided in the secondary battery according to the second embodiment of the present technology is as described above.

[Positive electrode for secondary battery]
The secondary battery according to the second embodiment of the present technology includes a positive electrode for a secondary battery. For detailed examples of the positive electrode for secondary battery, the following <4. An explanation will be given in the column “Example of Secondary Battery>.

[Electrolyte]
The secondary battery according to the second embodiment of the present technology includes an electrolytic solution. For detailed examples of the electrolytic solution, the following <4. An explanation will be given in the column “Example of Secondary Battery>.

<4. Example of secondary battery>
Next, an example of the secondary battery according to the second embodiment of the present technology will be described using the secondary battery described in FIGS. 1 to 4 as an example.

<4-1. Example of secondary battery (cylindrical lithium ion secondary battery)>
1 and 2 show a cross-sectional configuration of the secondary battery. In FIG. 2, a part of the wound electrode body 20 shown in FIG. 1 is enlarged. Here, the negative electrode for secondary battery of the first embodiment described above is applied to the negative electrode 22.

[Overall structure of secondary battery]
The secondary battery described here is a lithium secondary battery (lithium ion secondary battery) in which the capacity of the negative electrode 22 is obtained by occlusion and release of Li (lithium ion), which is an electrode reactant, and is a so-called cylindrical type.

In this secondary battery, for example, as shown in FIG. 1, a pair of insulating plates 12 and 13 and a wound electrode body 20 are housed inside a hollow cylindrical battery can 11. The wound electrode body 20 is wound, for example, after a positive electrode 21 and a negative electrode 22 are laminated via a separator 23.

The battery can 11 has, for example, a hollow structure in which one end is closed and the other end is opened. For example, the battery can 11 is formed of one or more of iron, aluminum, and alloys thereof. Has been. Nickel or the like may be plated on the surface of the battery can 11. The pair of insulating plates 12 and 13 are disposed so as to sandwich the wound electrode body 20, and extend perpendicular to the winding peripheral surface of the wound electrode body 20.

Since the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element (PTC element) 16 are caulked through the gasket 17 at the open end of the battery can 11, the battery can 11 is sealed. The battery lid 14 is formed of the same material as the battery can 11, for example. The safety valve mechanism 15 and the thermal resistance element 16 are provided inside the battery lid 14, and the safety valve mechanism 15 is electrically connected to the battery lid 14 via the thermal resistance element 16. In this safety valve mechanism 15, when the internal pressure becomes a certain level or more due to an internal short circuit or external heating, the disk plate 15 </ b> A is reversed to disconnect the electrical connection between the battery lid 14 and the wound electrode body 20. It is like that. The thermal resistance element 16 prevents abnormal heat generation due to a large current, and the resistance of the thermal resistance element 16 increases as the temperature rises. The gasket 17 is formed of, for example, an insulating material, and asphalt may be applied to the surface of the gasket 17.

For example, a center pin 24 is inserted into the winding center of the wound electrode body 20. For example, a positive electrode lead 25 formed of a conductive material such as aluminum is connected to the positive electrode 21, and a negative electrode lead 26 formed of a conductive material such as nickel is connected to the negative electrode 22. ing. For example, the positive electrode lead 25 is welded to the safety valve mechanism 15 and is electrically connected to the battery lid 14. For example, the negative electrode lead 26 is welded to the battery can 11 and is electrically connected to the battery can 11.

[Positive electrode]
The positive electrode 21 has a positive electrode active material layer 21B on one surface or both surfaces of a positive electrode current collector 21A. The positive electrode current collector 21A is formed of any one or more of conductive materials such as aluminum, nickel, and stainless steel, for example.

The positive electrode active material layer 21 </ b> B includes any one or more of lithium ion occluding and releasing materials as the positive electrode active material. However, the positive electrode active material layer 21B may further include any one kind or two or more kinds of other materials such as a positive electrode binder and a positive electrode conductive agent.

The positive electrode active material is preferably a lithium-containing compound, and more specifically, preferably one or both of a lithium-containing composite oxide and a lithium-containing phosphate compound. This is because a high energy density can be obtained.

“Lithium-containing composite oxide” is an oxide containing lithium and one or more elements (hereinafter referred to as “other elements”, excluding lithium (Li)) as constituent elements, and is a layered rock salt A crystal structure of a type or a spinel type. The “lithium-containing phosphate compound” is a phosphate compound containing lithium and one or more other elements as constituent elements and has an olivine type crystal structure.

The type of other element is not particularly limited as long as it is any one or more of arbitrary elements. Among them, the other elements are preferably any one or more of elements belonging to Groups 2 to 15 in the long-period periodic table. More specifically, the other element is more preferably any one or two or more metal elements of nickel (Ni), cobalt (Co), manganese (Mn), and iron (Fe). . This is because a high voltage can be obtained.

Among them, the lithium-containing composite oxide having a layered rock salt type crystal structure is preferably one or more of the compounds represented by formulas (21) to (23).

_{_{Li a Mn (1-bc)}} Ni b M11 c O (2-d) F e ··· (21)
(M11 is cobalt (Co), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), zirconium (Zr), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W), a to e being 0.8 ≦ a ≦ 1.2, 0 <b <0.5, 0 ≦ c ≦ 0.5, (b + c) <1, −0.1 ≦ d ≦ 0.2 and 0 ≦ e ≦ 0.1 are satisfied. However, the composition of lithium varies depending on the charge / discharge state, and a is the value of the fully discharged state.)

Li _a Ni _(1-b) M12 _b O _(2-c) F _d (22)
(M12 is cobalt (Co), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W), and a to d are 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 / discharge state Unlikely, a is the value of the fully discharged state.)

Li _a Co _(1-b) M13 _b O _(2-c) F _d (23)
(M13 is nickel (Ni), manganese (Mn), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper (Cu), zinc (Zn), molybdenum (Mo), tin (Sn), calcium (Ca), strontium (Sr), and tungsten (W), and a to d are 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 varies depending on the charge / discharge state, a is the value of the fully 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 .

The lithium-containing composite oxide having a spinel crystal structure is preferably one or more of the compounds represented by formula (24).

Li _a Mn _(2-b) M14 _b O _c F _d (24)
(M14 is cobalt (Co), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), chromium (Cr), iron (Fe), copper 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 differs depending on the charge / discharge state, and a Is the value of the fully discharged state.)

Specific examples of the lithium-containing composite oxide having a spinel crystal structure include LiMn ₂ O ₄ .

The lithium-containing phosphate compound having an olivine-type crystal structure is preferably one or more of the compounds represented by formula (25).

Li _a M15PO ₄ (25)
(M15 is cobalt (Co), manganese (Mn), iron (Fe), nickel (Ni), magnesium (Mg), aluminum (Al), boron (B), titanium (Ti), vanadium (V), niobium It is at least one of (Nb), copper (Cu), zinc (Zn), molybdenum (Mo), calcium (Ca), strontium (Sr), tungsten (W), and zirconium (Zr). 0.9 ≦ a ≦ 1.1, where the composition of lithium varies depending on the charge / discharge state, and a is the value of the complete discharge state.)

Specific examples of the lithium-containing phosphate compound having an olivine type crystal structure include LiFePO ₄ , LiMnPO ₄ , LiFe _0.5 Mn _0.5 PO _4, and LiFe _0.3 Mn _0.7 PO ₄ .

Note that the lithium-containing composite oxide may be one kind or two or more kinds of compounds represented by the formula (26).

(Li ₂ MnO ₃ ) _x (LiMnO ₂ ) _1-x (26)
(X satisfies 0 ≦ x ≦ 1, where the composition of lithium varies depending on the charge / discharge state, and x is the value of the complete discharge state.)

The positive electrode binder contains, for example, any one kind or two kinds or more of synthetic rubber and polymer material. Fluorine rubber, ethylene propylene diene, etc. Examples of the polymer material include polyvinylidene fluoride and polytetrafluoroethylene, a copolymer of vinylidene fluoride and hexafluoropyrene, polyacrylonitrile, polyacrylic acid polymer polyimide, and the like.

The positive electrode conductive agent includes, for example, one or more of carbon materials. Examples of the carbon material include graphite, carbon black, acetylene black, and ketjen black. Note that the positive electrode conductive agent may be a metal material, a conductive polymer, or the like as long as the material has conductivity.

In addition, the cathode material may be any one kind or two or more kinds of oxides, disulfides, chalcogenides, conductive polymers, and the like. Examples of the oxide include titanium oxide, vanadium oxide, and manganese dioxide. Examples of the disulfide include titanium disulfide and molybdenum sulfide. An example of the chalcogenide is niobium selenide. Examples of the conductive polymer include sulfur, polyaniline, and polythiophene. However, the positive electrode material is not limited to the series of materials described above, and may be other materials.

[Negative electrode]
The negative electrode 22 has a negative electrode active material layer 22B on one surface or both surfaces of a negative electrode current collector 22A.

The negative electrode current collector 22A is formed of, for example, one or more of conductive materials such as copper, nickel, and stainless steel. The surface of the negative electrode current collector 22A is preferably roughened. This is because the so-called anchor effect improves the adhesion of the negative electrode active material layer 22B to the negative electrode current collector 22A. In this case, the surface of the negative electrode current collector 22A only needs to be roughened at least in a region facing the negative electrode active material layer 22B. The roughening method is, for example, a method of forming fine particles using electrolytic treatment. This electrolytic treatment is a method of forming irregularities on the surface of the negative electrode current collector 22A by forming fine particles on the surface of the negative electrode current collector 22A using an electrolysis method in an electrolytic cell. A copper foil produced by an electrolytic method is generally called an electrolytic copper foil.

In order to prevent lithium metal from unintentionally depositing on the negative electrode 22 during charging, the negative electrode active material layer 22B generally has a larger chargeable capacity of the negative electrode material than the discharge capacity of the positive electrode 21. It is preferable. That is, the electrochemical equivalent of the negative electrode material capable of occluding and releasing Li is preferably larger than the electrochemical equivalent of the positive electrode 21.

In addition, the negative electrode active material layer 22 may include any one kind or two or more kinds of metal oxides and polymer compounds, for example. Examples of the metal oxide include iron oxide, ruthenium oxide, and molybdenum oxide. Examples of the polymer compound include polyacetylene, polyaniline, and polypyrrole. However, the negative electrode material is not limited to the series of materials described above, and may be other materials.

The negative electrode active material layer 22B is formed by any one method or two or more methods such as a coating method, a gas phase method, a liquid phase method, a thermal spraying method, and a firing method (sintering method). The application method is, for example, a method in which a negative electrode active material in the form of particles (powder) is mixed with a negative electrode binder and then dispersed in a solvent such as an organic solvent and then applied to the negative electrode current collector 22A. Examples of the vapor phase method include a physical deposition method and a chemical deposition method. More specifically, for example, a vacuum deposition method, a sputtering method, an ion plating method, a laser ablation method, a thermal chemical vapor deposition, a chemical vapor deposition (CVD) method, and a plasma chemical vapor deposition method. Examples of the liquid phase method include 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 22A. The firing method is, for example, a method of applying a heat treatment at a temperature higher than the melting point of the negative electrode binder or the like after being applied to the negative electrode current collector 22A using a coating method. As this firing method, for example, an atmosphere firing method, a reaction firing method, a hot press firing method, or the like can be used.

In this secondary battery, as described above, in order to prevent unintentional precipitation of lithium metal on the negative electrode 22 during charging, the electrochemical equivalent of the negative electrode material capable of occluding and releasing Li is the electric charge of the positive electrode. It is preferably larger than the chemical equivalent. In addition, when the open circuit voltage (that is, the battery voltage) at the time of full charge is 4.25 V or more, lithium ions are released per unit mass even when the same positive electrode active material is used as compared with the case of 4.2 V. Since the amount increases, the amounts of the positive electrode active material and the negative electrode active material are adjusted accordingly. Thereby, a high energy density can be obtained.

[Separator]
The separator 23 separates the positive electrode 21 and the negative electrode 22, thereby allowing lithium ions to pass through while preventing a short circuit of current caused by contact between the two electrodes. The separator 23 is, for example, a porous film such as a synthetic resin and ceramic, and may be a laminated film in which two or more kinds of porous films are laminated. Examples of the synthetic resin include polytetrafluoroethylene, polypropylene, and polyethylene.

Particularly, the separator 23 may have, for example, a polymer compound layer on one side or both sides of the above-described porous film (base material layer). This is because the adhesion of the separator 23 to the positive electrode 21 and the negative electrode 22 is improved, so that the distortion of the wound electrode body 20 is suppressed. As a result, 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 resistance is not easily increased even if charging and discharging are repeated, and the battery swelling is also suppressed. Is done.

The polymer compound layer includes, for example, a polymer material such as polyvinylidene fluoride. This is because it has excellent physical strength and is electrochemically stable. However, the polymer material may be a polymer material other than polyvinylidene fluoride. When forming this polymer compound layer, for example, after preparing a solution in which the polymer material is dissolved, the solution is applied to the base material layer and then dried. The substrate layer may be dipped in the solution and then dried.

[Electrolyte]
The separator 23 is impregnated with an electrolytic solution that is a liquid electrolyte. This electrolytic solution contains a solvent and an electrolyte salt, and may further contain other materials such as additives.

The solvent includes one or more of non-aqueous solvents such as organic solvents. Examples of the non-aqueous solvent include a cyclic carbonate ester, a chain carbonate ester, a lactone, a chain carboxylate ester, and a nitrile. This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained. Examples of the cyclic carbonate include ethylene carbonate, propylene carbonate, and butylene carbonate, and examples of the chain carbonate include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, and methyl propyl carbonate. Examples of the lactone include γ-butyrolactone and γ-valerolactone. Examples of the carboxylic acid ester include methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, and ethyl trimethyl acetate. Nitriles include, for example, acetonitrile, glutaronitrile, adiponitrile, methoxyacetonitrile, 3-methoxypropionitrile and the like.

Other non-aqueous solvents include, for example, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, 1,3-dioxane, 1 , 4-dioxane, N, N-dimethylformamide, N-methylpyrrolidinone, N-methyloxazolidinone, N, N′-dimethylimidazolidinone, nitromethane, nitroethane, sulfolane, trimethyl phosphate and dimethyl sulfoxide. This is because similar advantages can be obtained.

Of these, one or more of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate are preferred. This is because better battery capacity, cycle characteristics, storage characteristics, and the like can be obtained. In this case, high viscosity (high dielectric constant) solvents such as ethylene carbonate and propylene carbonate (for example, dielectric constant ε ≧ 30) and low viscosity solvents such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate (for example, viscosity ≦ 1 mPas). -A combination with s) is more preferred. This is because the dissociation property of the electrolyte salt and the ion mobility are improved.

In particular, the solvent may contain one kind or two or more kinds of unsaturated cyclic carbonate, halogenated carbonate, sultone (cyclic sulfonate) and acid anhydride. This is because the chemical stability of the electrolytic solution is improved. The unsaturated cyclic carbonate is a cyclic carbonate having one or more unsaturated bonds (carbon-carbon double bonds), and examples thereof include vinylene carbonate, vinyl ethylene carbonate, and methylene ethylene carbonate. The halogenated carbonate is a cyclic or chain carbonate containing one or more halogens as a constituent element. Examples of cyclic halogenated carbonates include 4-fluoro-1,3-dioxolan-2-one and 4,5-difluoro-1,3-dioxolan-2-one. Examples of the chain halogenated carbonate include fluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, and difluoromethyl methyl carbonate. Examples of sultone include propane sultone and propene sultone. Examples of the acid anhydride include succinic anhydride, ethanedisulfonic anhydride, and anhydrous sulfobenzoic acid. However, the solvent is not limited to the series of materials described above, and other materials may be used.

The electrolyte salt includes, for example, one or more of salts such as lithium salt. However, the electrolyte salt may contain a salt other than the lithium salt, for example. This other salt is, for example, a light metal salt other than a lithium salt.

Examples of the lithium salt include lithium hexafluorophosphate (LiPF ₆ ), lithium tetrafluoroborate (LiBF ₄ ), lithium perchlorate (LiClO ₄ ), lithium hexafluoroarsenate (LiAsF ₆ ), and 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 Examples include dilithium silicate (Li ₂ SiF ₆ ), lithium chloride (LiCl), and lithium bromide (LiBr). This is because excellent battery capacity, cycle characteristics, storage characteristics, and the like can be obtained.

Among these, at least one of LiPF ₆ , LiBF ₄ , LiClO ₄ and LiAsF ₆ is preferable, and LiPF ₆ is more preferable. This is because a higher effect can be obtained because the internal resistance is lowered. However, the electrolyte salt is not limited to the series of materials described above, and may be other materials.

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

[Operation of secondary battery]
This secondary battery operates as follows, for example. At the time of charging, lithium ions released from the positive electrode 21 are occluded in the negative electrode 22 through the electrolytic solution. On the other hand, at the time of discharge, lithium ions released from the negative electrode 22 are occluded in the positive electrode 21 through the electrolytic solution.

In this case, as described above, it is desirable to increase the charging voltage in order to release more lithium. More specifically, it is preferable to charge the secondary battery to a voltage (for example, 4.6 V) equal to or higher than 4.4 V (standard potential for lithium metal).

[Method for producing secondary battery]
This secondary battery is manufactured by the following procedure, for example.

First, the positive electrode 21 is manufactured. The above-described active material for a secondary battery, which is a positive electrode active material, and a positive electrode binder and a positive electrode conductive agent are mixed to obtain a positive electrode mixture. Subsequently, the positive electrode mixture is dispersed in an organic solvent or the like to obtain a paste-like positive electrode mixture slurry. Subsequently, the positive electrode mixture slurry is applied to both surfaces of the positive electrode current collector 21A and then dried to form the positive electrode active material layer 21B. Subsequently, the positive electrode active material layer 21B is compression molded using a roll press machine or the like. In this case, compression molding may be performed while heating, or compression molding may be repeated a plurality of times.

Further, the negative electrode 22 is produced by the same procedure as that of the positive electrode 21 described above. A negative electrode mixture in which a negative electrode active material, a negative electrode binder, a negative electrode conductive agent, and the like are mixed is dispersed in an organic solvent or the like to obtain a paste-like negative electrode mixture slurry. Subsequently, the negative electrode mixture slurry is applied to both surfaces of the negative electrode current collector 22A and then dried to form the negative electrode active material layer 22B, and then the negative electrode active material layer 22B is compression molded.

Finally, a secondary battery is assembled using the positive electrode 21 and the negative electrode 22. The positive electrode lead 25 is attached to the positive electrode current collector 21A using a welding method or the like, and the negative electrode lead 26 is attached to the negative electrode current collector 22A using a welding method or the like. Subsequently, after the positive electrode 21 and the negative electrode 22 are laminated via the separator 23 and wound to produce the wound electrode body 20, the center pin 24 is inserted into the winding center. Subsequently, the wound electrode body 20 is accommodated in the battery can 11 while being sandwiched between the pair of insulating plates 12 and 13. In this case, the tip of the positive electrode lead 25 is attached to the safety valve mechanism 15 using a welding method or the like, and the tip of the negative electrode lead 26 is attached to the battery can 11 using a welding method or the like. Subsequently, an electrolytic solution in which an electrolyte salt is dispersed in a solvent is injected into the battery can 11 and impregnated in the separator 23. Subsequently, the battery lid 14, the safety valve mechanism 15, and the heat sensitive resistance element 16 are caulked to the opening end portion of the battery can 11 through the gasket 17.

[Operation and effect of secondary battery]
According to this cylindrical secondary battery, the positive electrode active material layer 21B of the positive electrode 21 includes the above-described secondary battery active material as the positive electrode active material. Therefore, it is possible to more smoothly occlude and release Li while improving the energy density. Therefore, a higher battery capacity can be obtained.

<4-2. Example of secondary battery (laminated film type lithium ion secondary battery)>
FIG. 3 shows an exploded perspective configuration of another secondary battery, and FIG. 4 is an enlarged cross-sectional view taken along line IV-IV of the spirally wound electrode body 30 shown in FIG. However, FIG. 3 shows a state in which the spirally wound electrode body 30 and the two exterior members 40 are separated from each other. In the following, the components of the cylindrical secondary battery already described will be referred to as needed. Here, the negative electrode for secondary battery of the first embodiment described above is applied to the negative electrode 34.

[Overall structure of secondary battery]
The secondary battery described here is a so-called laminate film type lithium ion secondary battery. For example, as shown in FIG. 3, the wound electrode body 30 is housed in a film-shaped exterior member 40. Yes. For example, the wound electrode body 30 is wound after the positive electrode 33 and the negative electrode 34 are stacked via the separator 35 and the electrolyte layer 36. A positive electrode lead 31 is attached to the positive electrode 33, and a negative electrode lead 32 is attached to the negative electrode 34. The outermost peripheral part of the wound electrode body 30 is protected by a protective tape 37.

The positive electrode lead 31 and the negative electrode lead 32 are led out in the same direction from the inside of the exterior member 40 to the outside, for example. The positive electrode lead 31 is formed of a conductive material such as aluminum, and the negative electrode lead 32 is formed of a conductive material such as copper, nickel, or stainless steel. These conductive materials have, for example, a thin plate shape or a mesh shape.

The exterior member 40 is, for example, a laminate film in which a fusion layer, a metal layer, and a surface protective layer are laminated in this order. The exterior member 40 is obtained by, for example, laminating two laminated films so that the fusion layer faces the spirally wound electrode body 30 and then fusing the outer peripheral edges of the fusion layers. . However, the two laminated films may be bonded together with an adhesive or the like. The fusion layer is, for example, a film made of polyethylene or polypropylene. The metal layer is, for example, an aluminum foil. The surface protective layer is, for example, a film such as nylon and polyethylene terephthalate.

Especially, it is preferable that the exterior member 40 is an aluminum laminate film in which a polyethylene film, an aluminum foil, and a nylon film are laminated in this order. However, the exterior member 40 may be a laminate film having another laminated structure, a polymer film such as polypropylene, or a metal film.

Between the exterior member 40 and the positive electrode lead 31 and the negative electrode lead 32, for example, an adhesion film 41 is inserted to prevent intrusion of outside air. The adhesion film 41 is formed of a material having adhesion to the positive electrode lead 31 and the negative electrode lead 32. The adhesive material is, for example, a polyolefin resin, and more specifically, polyethylene, polypropylene, modified polyethylene, modified polypropylene, and the like.

The positive electrode 33 has, for example, a positive electrode active material layer 33B on both surfaces of the positive electrode current collector 33A, and the negative electrode 34 has, for example, a negative electrode active material layer 34B on both surfaces of the negative electrode current collector 34A. . The configurations of the positive electrode current collector 33A, the positive electrode active material layer 33B, the negative electrode current collector 34A, and the negative electrode active material layer 34B are respectively the positive electrode current collector 21A, the positive electrode active material layer 21B, the negative electrode current collector 22A, and the negative electrode active material layer. The configuration is the same as 22B. That is, the positive electrode active material layer 33 </ b> B of the positive electrode 33 that is a secondary battery electrode contains the above-described secondary battery active material as the positive electrode active material. The configuration of the separator 35 is the same as the configuration of the separator 23.

[Electrolyte layer]
The electrolyte layer 36 is a so-called gel electrolyte in which an electrolytic solution is held by a polymer compound. This is because high ionic conductivity (for example, 1 mS / cm or more at room temperature) is obtained and leakage of the electrolytic solution is prevented. The electrolyte layer 36 may further contain other materials such as additives.

The polymer compound includes one kind or two or more kinds of polymer materials. This polymeric material is, for example, polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, polyhexafluoropropylene, polyethylene oxide, polypropylene oxide, polyphosphazene, polysiloxane, polyvinyl fluoride, polyvinyl acetate, polyvinyl alcohol, poly Examples thereof include methyl methacrylate, polyacrylic acid, polymethacrylic acid, styrene-butadiene rubber, nitrile-butadiene rubber, polystyrene and polycarbonate. In addition, the polymer material may be a copolymer. This copolymer is, for example, a copolymer of vinylidene fluoride and hexafluoropyrene. Among these, polyvinylidene fluoride and a copolymer of vinylidene fluoride and hexafluoropyrene are preferable, and polyvinylidene fluoride is more preferable. This is because it is electrochemically stable.

The composition of the electrolytic solution is the same as that of the cylindrical type, for example. However, in the electrolyte layer 36 which is a gel electrolyte, the solvent of the electrolytic solution is a wide concept including not only a liquid solvent but also a material having ion conductivity capable of dissociating the electrolyte salt. Therefore, when using a polymer compound having ion conductivity, the polymer compound is also included in the solvent.

In addition, it may replace with the gel-like electrolyte layer 36 and may use electrolyte solution as it is. In this case, the separator 35 is impregnated with the electrolytic solution.

[Operation of secondary battery]
This secondary battery operates as follows, for example. During charging, lithium ions released from the positive electrode 33 are occluded in the negative electrode 34 through the electrolyte layer 36. On the other hand, at the time of discharging, lithium ions released from the negative electrode 34 are occluded in the positive electrode 33 through the electrolyte layer 36. Even in this case, it is desirable to increase the charging voltage in order to release more lithium. More specifically, it is preferable to set the charging voltage to a voltage (for example, 4.6 V) equal to or higher than 4.4 V (vs. lithium metal standard potential).

[Method for producing secondary battery]
The secondary battery provided with the gel electrolyte layer 36 is manufactured, for example, by the following three types of procedures.

In the first procedure, the positive electrode 33 and the negative electrode 34 are manufactured by the same manufacturing procedure as that of the positive electrode 21 and the negative electrode 22. In this case, the positive electrode active material layer 33B is formed on both surfaces of the positive electrode current collector 33A to produce the positive electrode 33, and the negative electrode active material layer 34B is formed on both surfaces of the negative electrode current collector 34A to produce the negative electrode 34. To do. Subsequently, after preparing a precursor solution containing an electrolytic solution, a polymer compound, and a solvent such as an organic solvent, the precursor solution is applied to the positive electrode 33 and the negative electrode 34 to form a gel electrolyte layer 36. . Subsequently, the positive electrode lead 31 is attached to the positive electrode current collector 33A using a welding method or the like, and the negative electrode lead 32 is attached to the negative electrode current collector 34A using a welding method or the like. Subsequently, after the positive electrode 33 and the negative electrode 34 are stacked via the separator 35 and wound to produce the wound electrode body 30, a protective tape 37 is attached to the outermost periphery. Subsequently, after sandwiching the wound electrode body 30 between the two film-shaped exterior members 40, the outer peripheral edge portions of the exterior members 40 are bonded to each other using a heat fusion method or the like. The spirally wound electrode body 30 is sealed inside. In this case, the adhesion film 41 is inserted between the positive electrode lead 31 and the negative electrode lead 32 and the exterior member 40.

In the second procedure, the positive electrode lead 31 is attached to the positive electrode 33 and the negative electrode lead 52 is attached to the negative electrode 34. Subsequently, the positive electrode 33 and the negative electrode 34 are stacked via the separator 35 and wound to produce a wound body that is a precursor of the wound electrode body 30, and then a protective tape 37 is provided on the outermost peripheral portion thereof. Paste. Subsequently, after the wound body is arranged between the two film-like exterior members 40, the remaining outer peripheral edge portion excluding the outer peripheral edge portion on one side is bonded by using a heat sealing method or the like, and the bag The wound body is housed inside the shaped exterior member 40. Subsequently, an electrolytic solution is prepared by mixing an electrolyte, a monomer that is a raw material of the polymer compound, a polymerization initiator, and another material such as a polymerization inhibitor. Subsequently, after the electrolyte composition is injected into the bag-shaped exterior member 40, the exterior member 40 is sealed using a heat fusion method or the like. Subsequently, the monomer is thermally polymerized to form a polymer compound. As a result, the polymer compound is impregnated with the electrolytic solution, and the polymer compound gels, so that the electrolyte layer 36 is formed.

In the third procedure, a wound body is produced and stored in the bag-shaped exterior member 40 in the same manner as in the second procedure described above, except that the separator 35 coated with the polymer compound on both sides is used. The polymer compound applied to the separator 35 is, for example, a polymer (a homopolymer, a copolymer, and a multi-component copolymer) containing vinylidene fluoride as a component. Specifically, the homopolymer is, for example, polyvinylidene fluoride. The copolymer is, for example, a binary copolymer containing vinylidene fluoride and hexafluoropropylene as components. The multi-component copolymer is, for example, a ternary copolymer containing vinylidene fluoride, hexafluoropropylene, and chlorotrifluoroethylene as components. In addition to the polymer containing vinylidene fluoride as a component, one or more other polymer compounds may be used. Subsequently, after the electrolytic solution is prepared and injected into the exterior member 40, the opening of the exterior member 40 is sealed using a thermal fusion method or the like. Subsequently, the exterior member 40 is heated while applying a load, and the separator 35 is brought into close contact with the positive electrode 33 and the negative electrode 34 through the polymer compound. As a result, the polymer compound is impregnated with the electrolytic solution, and the polymer compound gels, so that the electrolyte layer 36 is formed.

In this third procedure, swelling of the secondary battery is suppressed more than in the first procedure. In the third procedure, since the monomer or solvent that is a raw material of the polymer compound hardly remains in the electrolyte layer 36 than in the second procedure, the formation process of the polymer compound is controlled well. For this reason, sufficient adhesion is obtained between the positive electrode 33, the negative electrode 34 and the separator 35 and the electrolyte layer 36.

[Operation and effect of secondary battery]
According to this laminated film type secondary battery, the positive electrode active material layer 33B of the positive electrode 33 contains the above-described secondary battery active material as the positive electrode active material, and therefore, excellent for the same reason as in the case of the cylindrical type. Battery characteristics can be obtained. Other operations and effects are the same as in the case of the cylindrical type.

<5. Applications of secondary batteries>
The use of the secondary battery will be described in detail.

<5-1. Overview of secondary battery applications>

The secondary battery can be used for machines, devices, instruments, devices, and systems (a collection of multiple devices) that can use the secondary battery as a power source for driving or a power storage source for storing power. There is no particular limitation. The ion secondary battery used as a power source may be a main power source (a power source used preferentially) or an auxiliary power source (a power source used in place of or switched from the main power source). When an ion secondary battery is used as an auxiliary power source, the type of main power source is not limited to the secondary battery.

The usage of the secondary battery is, for example, as follows. Electronic devices (including portable electronic devices) such as video cameras, digital still cameras, mobile phones, notebook computers, cordless phones, headphone stereos, portable radios, portable televisions, and portable information terminals. It is a portable living device such as an electric shaver. Storage devices such as backup power supplies and memory cards. Electric tools such as electric drills and electric saws. It is a battery pack used for a notebook computer or the like as a detachable power source. Medical electronic devices such as pacemakers and hearing aids. An electric vehicle such as an electric vehicle (including a hybrid vehicle). It is an electric power storage system such as a home battery system that stores electric power in case of an emergency. Of course, applications other than those described above may be used.

Especially, 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. This is because, since excellent battery characteristics are required, the performance can be effectively improved by using the secondary battery of the present technology. The battery pack is a power source using a secondary battery, and is a so-called assembled battery. An electric vehicle is a vehicle that operates (runs) using a secondary battery as a driving power source, and may be an automobile (such as a hybrid automobile) that includes a drive source other than the secondary battery as described above. The power storage system is a system that uses a secondary battery as a power storage source. For example, in a household power storage system, power is stored in a secondary battery, which is a power storage source, so that household electrical products can be used using the power. An electric power tool is a tool in which a movable part (for example, a drill etc.) moves, using a secondary battery as a driving power source. An electronic device is a device that exhibits various functions using a secondary battery as a driving power source (power supply source).

Here, some application examples of the secondary battery will be specifically described. In addition, since the structure of each application example demonstrated below is an example to the last, it can change suitably.

<5-2. Third Embodiment (Battery Pack)>
The battery pack according to the third embodiment of the present technology includes the secondary battery according to the second embodiment of the present technology, a control unit that controls a usage state of the secondary battery, and an instruction from the control unit. And a switch unit that switches a usage state of the secondary battery. The battery pack according to the third embodiment of the present technology includes the secondary battery according to the second embodiment of the present technology having excellent battery characteristics, which leads to an improvement in the performance of the battery pack.

Hereinafter, a battery pack according to a third embodiment of the present technology will be described with reference to the drawings.

FIG. 5 shows a block configuration of the battery pack. This battery pack includes, for example, a control unit 61, a power source 62, a switch unit 63, a current measurement unit 64, a temperature detection unit 65, and a voltage detection unit inside a housing 60 formed of a plastic material or the like. 66, a switch control unit 67, a memory 68, a temperature detection element 69, a current detection resistor 70, a positive terminal 71 and a negative terminal 72.

The control unit 61 controls the operation of the entire battery pack (including the usage state of the power supply 62), and includes, for example, a central processing unit (CPU). The power source 62 includes one or more secondary batteries (not shown). The power source 62 is, for example, an assembled battery including two or more secondary batteries, and the connection form of these secondary batteries may be in series, in parallel, or a mixture of both. For example, the power source 62 includes six secondary batteries connected in two parallel three series.

The switch unit 63 switches the usage state of the power source 62 (whether or not the power source 62 can be connected to an external device) according to 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, a discharging diode (all not shown), and the like. The charge control switch and the discharge control switch are semiconductor switches such as a field effect transistor (MOSFET) using a metal oxide semiconductor, for example.

The current measurement unit 64 measures current using the current detection resistor 70 and outputs the measurement result to the control unit 61. The temperature detection unit 65 measures the temperature using the temperature detection element 69 and outputs the measurement result to the control unit 61. This temperature measurement result 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, converts the measured voltage from analog to digital, and supplies the converted voltage to the control unit 61.

The switch control unit 67 controls the operation of the switch unit 63 in accordance with signals input from 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) and controls the charging current not to flow through the current path of the power source 62. . As a result, the power source 62 can only discharge through the discharging diode. The switch control unit 67 is configured to cut off the charging current when a large current flows during charging, for example.

Further, the switch control unit 67 disconnects the switch unit 63 (discharge control switch) so that the discharge current does not flow in the current path of the power source 62 when the battery voltage reaches the overdischarge detection voltage, for example. . As a result, the power source 62 can only be charged via the charging diode. For example, the switch control unit 67 is configured to cut off the discharge current when a large current flows during discharging.

In the secondary battery, for example, the overcharge detection voltage is 4.2V ± 0.05V, and the overdischarge detection voltage is 2.4V ± 0.1V.

The memory 68 is, for example, an EEPROM which is a nonvolatile memory. The memory 68 stores, for example, numerical values calculated by the control unit 61 and information (for example, internal resistance in the initial state) of the secondary battery measured in the manufacturing process stage. 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 to the control unit 61, and is, for example, a thermistor.

The positive electrode terminal 71 and the negative electrode terminal 72 are connected to an external device (for example, a notebook personal computer) operated using a battery pack, an external device (for example, a charger) used to charge the battery pack, or the like. Terminal. Charging / discharging of the power source 62 is performed via the positive terminal 71 and the negative terminal 72.

<5-3. Fourth Embodiment (Electric Vehicle)>
The electric vehicle according to the fourth embodiment of the present technology includes a secondary battery according to the second embodiment of the present technology, a conversion unit that converts electric power supplied from the secondary battery into driving power, and driving power. It is an electric vehicle provided with the drive part driven according to this and the control part which controls the use condition of a multivalent ion secondary battery. Since the electric vehicle according to the fourth embodiment of the present technology includes the secondary battery according to the second embodiment of the present technology having excellent battery characteristics, the performance of the electric vehicle is improved.

Hereinafter, an electric vehicle according to a fourth embodiment of the present technology will be described with reference to the drawings.

FIG. 6 shows a block configuration of a hybrid vehicle which is an example of an electric vehicle. This electric vehicle includes, for example, a control unit 74, an engine 75, a power source 76, a driving motor 77, a differential device 78, a generator 79, and a transmission 80 inside a metal casing 73. And a clutch 81, inverters 82 and 83, and various sensors 84. In addition, the electric vehicle includes, for example, a front wheel drive shaft 85 and a front wheel 86 connected to the differential device 78 and the transmission 80, and a rear wheel drive shaft 87 and a rear wheel 88.

This electric vehicle can run using, for example, either the engine 75 or 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, the driving force (rotational force) of the engine 75 is transmitted to the front wheels 86 or the rear wheels 88 via, for example, a differential device 78, a transmission 80, and a clutch 81 which are driving units. . The rotational force of the engine 75 is also transmitted to the generator 79, and the generator 79 generates AC power using the rotational force. The AC power is converted into DC power via the inverter 83, and the power source 76. On the other hand, when the motor 77 which is the conversion unit is used as a power source, the power (DC power) supplied from the power source 76 is converted into AC power via the inverter 82, and the motor 77 is driven using the AC power. . The driving force (rotational force) converted from electric power by the motor 77 is transmitted to the front wheels 86 or the rear wheels 88 via, for example, a differential device 78, a transmission 80, and a clutch 81, which are driving units.

When the electric vehicle decelerates via a braking mechanism (not shown), the resistance force at the time of deceleration is transmitted as a rotational force to the motor 77, and the motor 77 generates AC power using the rotational force. Good. This AC power is preferably converted into DC power via the inverter 82, and the DC regenerative power is preferably stored in the power source 76.

The control unit 74 controls the operation of the entire electric vehicle and includes, for example, a CPU. The power source 76 includes one or more secondary batteries (not shown). The power source 76 may be connected to an external power source and can store power by receiving power supply from the external power source. The various sensors 84 are used to control the opening of a throttle valve (not shown) (throttle opening) by controlling the rotational speed of the engine 75, for example. The various sensors 84 include, for example, a speed sensor, an acceleration sensor, an engine speed sensor, and the like.

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

<5-4. Fifth Embodiment (Power Storage System)>
The power storage system according to the fifth embodiment of the present technology includes the secondary battery according to the second embodiment of the present technology, one or more electric devices to which power is supplied from the secondary battery, and a secondary battery. And a control unit that controls power supply from the battery to the electric device. Since the power storage system of the fifth embodiment according to the present technology includes the secondary battery according to the second embodiment of the present technology having excellent battery characteristics, the power storage performance is improved.

Hereinafter, a power storage system according to a fifth embodiment of the present technology will be described with reference to the drawings.

FIG. 7 shows a block configuration of the power storage system. This power storage system includes, for example, a control unit 90, a power source 91, a smart meter 92, and a power hub 93 in a house 89 such as a general house and a commercial building.

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

Note that the electric device 94 includes, for example, one or more home appliances, and the home appliances are, for example, a refrigerator, an air conditioner, a television, and a water heater. The private power generator 95 is, for example, any one type or two or more types such as a solar power generator and a wind power generator. The electric vehicle 96 is, for example, one type or two or more types such as an electric vehicle, an electric motorcycle, and a hybrid vehicle. The centralized electric power system 97 is, for example, one type or two or more types such as a thermal power plant, a nuclear power plant, a hydroelectric power plant, and a wind power plant.

The control unit 90 controls the operation of the entire power storage system (including the usage state of the power supply 91), and includes, for example, a CPU. The power source 91 includes one or more secondary batteries (not shown). The smart meter 92 is, for example, a network-compatible power meter installed in a power consumer's house 89 and can communicate with the power supplier. Accordingly, for example, the smart meter 92 enables efficient and stable energy supply by controlling the balance between supply and demand in the house 89 while communicating with the outside.

In this power storage system, for example, power is accumulated in the power source 91 from the centralized power system 97 that is an external power source via the smart meter 92 and the power hub 93, and the power hub 93 is connected from the solar power generator 95 that is an independent power source. Power is accumulated in the power source 91 through the power source 91. Since the electric power stored in the power source 91 is supplied to the electric device 94 and the electric vehicle 96 in accordance with an instruction from the control unit 90, the electric device 94 can be operated and the electric vehicle 96 can be charged. . In other words, the power storage system is a system that makes it possible to store and supply power in the house 89 using the power source 91.

The power stored in the power supply 91 can be used arbitrarily. For this reason, for example, power is stored in the power source 91 from the centralized power system 97 at midnight when the amount of electricity used is low, and the power stored in the power source 91 is used during the day when the amount of electricity used is high. it can.

The power storage system described above may be installed for each house (one household), or may be installed for each of a plurality of houses (multiple households).

<5-5. Sixth Embodiment (Electric Tool)>
The electric tool of 6th Embodiment which concerns on this technique is an electric tool provided with the secondary battery of 2nd Embodiment which concerns on this technique, and the movable part to which electric power is supplied from a secondary battery. Since the electric tool of the sixth embodiment according to the present technology includes the secondary battery according to the second embodiment of the present technology having excellent battery characteristics, the performance of the electric tool is improved.

Hereinafter, a power tool according to a sixth embodiment of the present technology will be described with reference to the drawings.

FIG. 8 shows a block configuration of the electric tool. This electric tool is, for example, an electric drill, and includes a control unit 99 and a power supply 100 inside a tool main body 98 formed of a plastic material or the like. 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 control unit 99 controls the operation of the entire power tool (including the usage state of the power supply 100), and includes, for example, a CPU. The power supply 100 includes one or more secondary batteries (not shown). The control unit 99 supplies power from the power supply 100 to the drill unit 101 in response to an operation switch (not shown).

<5-6. Seventh Embodiment (Electronic Device)>
The electronic device of 7th Embodiment which concerns on this technique is an electronic device provided with the secondary battery of 2nd Embodiment which concerns on this technique as an electric power supply source. As described above, the electronic device according to the tenth embodiment of the present technology is a device that exhibits various functions using the secondary battery as a driving power source (power supply source). The electronic device according to the seventh embodiment of the present technology includes the secondary battery according to the second embodiment of the present technology having excellent battery characteristics, which leads to an improvement in performance of the electronic device.

The effect of the present technology should be obtained without depending on the type of electrode reactant if it is an electrode reactant used in a secondary battery. An effect can be obtained.

Further, the effects described in the present specification are merely examples and are not limited, and other effects may be obtained.

In addition, the present technology may have the following configurations.
[1]
Negative electrode active material powder;
A coating layer formed on the negative electrode active material powder;
A binder, and
A negative electrode for a secondary battery, wherein the coating layer includes a hydrocarbon polymer containing at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate, and a carbonate.
[2]
The coating layer is a component formed by heat-treating a carboxymethylcellulose-based water-soluble polymer, a component formed by heat-treating a polyacrylic acid-based water-soluble polymer, and a methacrylic acid-based water-soluble polymer The negative electrode for a secondary battery according to [1], comprising at least one selected from the group consisting of components formed thereby.
[3]
[1] or [2], wherein the coating layer includes at least one selected from the group consisting of a carboxymethylcellulose-based water-soluble polymer, a polyacrylic acid-based water-soluble polymer, and a methacrylic acid-based water-soluble polymer. The negative electrode for secondary batteries as described.
[4]
The covering layer includes at least one selected from the group consisting of fibrous carbon, vapor grown carbon fiber, carbon nanotube, graphene, and powdered carbon, according to any one of [1] to [3]. Negative electrode for secondary battery.
[5]
The negative electrode for a secondary battery according to any one of [1] to [4], wherein the coating layer contains a carboxylic acid and / or a carboxylate.
[6]
The negative electrode for a secondary battery according to [5], wherein the carboxylate is sodium oxalate or lithium oxalate.
[7]
The negative electrode for a secondary battery according to any one of [1] to [6], wherein the binder is contained in the coating layer.
[8]
The negative electrode for a secondary battery according to any one of [1] to [7], wherein the binder is a polyvinylidene fluoride polymer.
[9]
The negative electrode for a secondary battery according to any one of [1] to [8], wherein the negative electrode active material powder includes a carbon-based material and / or a silicon-based material.
[10]
The negative electrode for a secondary battery according to any one of [1] to [9], comprising N-methylpyrrolidone.
[11]
A negative electrode for a secondary battery;
A positive electrode for a secondary battery;
An electrolyte solution,
The negative electrode for a secondary battery comprises a negative electrode active material powder,
A coating layer formed on the negative electrode active material powder;
A binder, and
The secondary battery, wherein the coating layer includes a hydrocarbon polymer containing at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate, and a carbonate.
[12]
[2] to [10] the secondary battery negative electrode according to any one of
A positive electrode for a secondary battery;
A secondary battery comprising at least an electrolytic solution.
[13]
[11] The secondary battery according to [12],
A control unit for controlling a usage state of the secondary battery;
A battery pack comprising: a switch unit that switches a use state of the ion secondary battery in accordance with an instruction from the control unit.
[14]
[11] or the secondary battery according to [12],
A conversion unit that converts electric power supplied from the secondary battery into a driving force, and a driving unit that is driven according to the driving force;
And a control unit that controls a usage state of the secondary battery.
[15]
[11] or the secondary battery according to [12],
One or more electrical devices to which power is supplied from the secondary battery;
And a control unit that controls power supply from the secondary battery to the electrical device.
[16]
[11] or the secondary battery according to [12],
And a movable part to which electric power is supplied from the secondary battery.
[17]
[11] An electronic device comprising the secondary battery according to [12] as a power supply source.

Hereinafter, the effects of the present technology will be described in detail with examples. Note that the scope of the present technology is not limited to the examples.

<Method for producing secondary battery negative electrode>
The secondary battery negative electrode is formed by forming a coating layer on the surface of the negative electrode active material powder, and after coating, drying and rolling on a copper foil current collector foil with a roll press to a predetermined width A slit was made to obtain a negative electrode for a secondary battery for winding an electrode element.

<Method for producing positive electrode for secondary battery>
A positive electrode for a secondary battery uses a polyvinylidene fluoride polymer (hereinafter sometimes referred to as PVDF), a positive electrode active material, and a conductive material in an N-methylpyrrolidone (hereinafter sometimes referred to as NMP) solvent. After forming a paint, an aluminum current collector foil was used to obtain a positive electrode by an electrode preparation method similar to that of the negative electrode.

<Method for manufacturing secondary battery>
The form of the secondary battery cell is a cylindrical shape of ICR18650 size, and after creating an electrode element with a machine constituting a predetermined wound electrode element, inserting it into a predetermined can, and performing current collecting lead welding, An electrolyte prepared in advance with EC / EMC = 1/3 and 1 mol / kg of LiPF ₆ (≈1.25 mol / L) was injected, and sealed with a sealing body equipped with a predetermined safety valve interposed therebetween, The assembly of the secondary battery cell was completed. Next, initial charge was performed using the produced secondary battery. The initial charge is performed at a 0.2 ItA charge rate, a high temperature aging process is performed to promote SEI film formation, and after full charge, an open circuit voltage defect screening inspection is performed. On the other hand, the following cell evaluation was performed.

<Cycle evaluation method>
The test conditions were the following severe low-temperature (0 ° C.) cycle evaluation, which was the most severe cycle evaluation due to Li precipitation. The test conditions were as follows: the following charge / discharge cycle was performed, and the following second step low-temperature cycle capacity was derived as a maintenance factor when the capacity at the initial 10 cycles was set to 100, and summarized in Table 1 below.
-Charging: 0.5C4.2V5% current Cut
・ Discharge: 0.5C3VCut
-First step: (1-10 cycles): Charging / discharging 23 ° C
Second step: (11 to 60 cycles): Charging / discharging 0 ° C (0 ° C 50 cycles)
-Third step: (61-70 cycles): Charging / discharging 23 ° C

<Example 1>
Graphite powder is used as the main active material, and as a method for forming the coating layer, a carboxymethyl cellulose-based water-soluble polymer (hereinafter sometimes referred to as CMC) 1% aqueous solution (Serogen 4H, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Kneaded, transferred to a predetermined metal container, roughly dried at 100 ° C, then heat treated (vacuum heat treatment device) at 300 ° C for 24 hours to thermally denature CMC, and at the same time completely remove the adsorbed water A first coating layer was formed. After that, as an electrode mixture forming method, knead with an NMP-PVDF-based dissolved binder solution, apply and dry on a copper foil current collector foil, roll-mold with a roll press, slit to a predetermined width, A negative electrode for winding an electrode element was obtained. In accordance with all the other positive electrode, cell configuration, cycle evaluation test conditions, etc., a secondary battery-1 was produced.

<Example 2>
A secondary battery-2 was produced in the same manner as in Example 1 except that the PVDF powder was mixed in the CMC aqueous solution as the method for forming the coating layer described in Example 1.

<Example 3>
A secondary battery-3 was produced in the same manner as in Example 1 except that the coating layer formation method described in Example 1 was mixed with CMC aqueous solution and Li oxalate powder.

<Comparative Example 1>
A secondary battery A was fabricated in the same manner as in Example 1 except that the coating layer described in Example 1 was not formed.

<Comparative example 2>
The film layer described in Example 1 was not formed, and a copper foil current collector was prepared by using a water-soluble dispersion of CMC aqueous solution and styrene-butadiene rubber (hereinafter sometimes referred to as SBR) as an electrode paint. A secondary battery B was prepared in the same manner as in Example 1 except for the case after coating and drying on the foil.

<Example 4>
A secondary battery 4 was produced in the same manner as in Example 1 except that a mixed powder of 90% by mass of graphite powder and 10% by mass of SiO powder was used as the main active material.

<Example 5>
A secondary battery-5 was produced in the same manner as in Example 2 except that the main active material was a mixed powder of 90% by mass of graphite powder and 10% by mass of SiO powder.

<Example 6>
A secondary battery-6 was produced in the same manner as in Example 3 except that a mixed powder of 90% by mass of graphite powder and 10% by mass of SiO powder was used as the main active material.

<Comparative Example 3>
A secondary battery C was produced in the same manner as in Comparative Example 1 except that the main active material was a mixed powder of 90% by mass of graphite powder and 10% by mass of SiO powder.

<Comparative example 4>
A secondary battery D was produced in the same manner as in Comparative Example 2 except that the main active material was a mixed powder of 90% by mass of graphite powder and 10% by mass of SiO powder.

<Evaluation results and discussion>
The evaluation results of Examples 1 to 6 (secondary battery-1 to secondary battery-6) and Comparative Examples 1 to 4 (secondary battery-A to secondary battery-D) are shown in Table 1 below.

FIG. 1 shows the capacity for the 0 ° C. cycle and the 23 ° C. cycle for Example 1 (secondary battery-1), Example 3 (secondary battery-3), and Comparative Example 1 (secondary battery-A). The relationship between a maintenance rate (%) and the number of cycles (times) is shown.

As shown in Table 1, Examples 1 to 3 (secondary battery-1 to secondary battery-3) having a coating layer formed thereon were compared with Comparative Examples 1 to 2 (secondary battery-A) having no coating layer. As a result, the cycle capacity retention rate (%) at 50 ° C. for 50 cycles was higher than that of the secondary battery-B).

Further, as shown in FIG. 1 (vertical axis: capacity retention rate (%) vs horizontal axis: cycle number (times)), the second step of 0 ° C. cycle (cycle number: 11 to 60 times) and In a three-step 23 ° C. cycle (number of cycles: 61 to 70 times), Examples 1 to 3 (secondary battery-1 to secondary battery-3) are compared to Comparative Example 1 (secondary battery-A). In contrast, the cycle capacity retention rate at 50 ° C. at 50 ° C. was high, and the low-temperature cycle characteristics were good.

Examples 4 to 6 (secondary battery-4 to secondary battery-6) and Comparative Examples 3 to 4 (secondary battery-C to secondary battery-D) composed of graphite and SiO as negative electrode active material powders When the cycle capacity retention rate (%) at 0 ° C. and 50 cycles was compared, the difference in the presence or absence of the coating layer became more remarkable. That is, Examples 4 to 6 (secondary battery-4 to secondary battery-6) having a coating layer are Comparative Examples 3 to 4 (secondary battery-C to secondary battery-D) having no coating layer. On the other hand, the cycle capacity retention rate (%) at 50 ° C. and 50 cycles was high. At that time, Examples 4 to 6 (secondary battery-4 to secondary battery-6) having a coating layer were used in Comparative Example 4 (secondary battery-D) in which the paint system forming the negative electrode mixture was water CMC. However, the difference was more dominant.

According to the secondary batteries-1 to secondary battery-6 of Examples 1 to 6, side reaction such as gas generation due to side reaction with the reactive sites on the carbon surface by the coating layer, improvement of ion conductivity, It has been confirmed that a good improvement effect can be obtained in the charge / discharge cycle characteristics of the secondary battery cell at a low temperature by improving the mechanical and electrochemical stability.

As mentioned above, although this technique was demonstrated, giving an embodiment and an Example, this technique is not limited to the aspect demonstrated in embodiment and an Example, A various deformation | transformation is possible.

For example, the case where the battery structure is a cylindrical type and a laminate film type is described as an example, and the case where the battery element has a winding structure is described as an example, but the present invention is not limited thereto. The secondary battery of the present technology can be applied to cases having other battery structures such as a square type, a coin type, and a button type, and also applicable to cases where the battery element has another structure such as a laminated structure. It is.

Further, for example, the electrode reactant may be other group 1 elements such as sodium (Na) and potassium (K) in addition to lithium (Li), or group 2 elements such as magnesium (Mg) and calcium (Ca). Alternatively, other light metals such as aluminum (Al) and sulfur (S) may be used. Since the effect of the present technology should be obtained without depending on the type of the electrode reactant, the same effect can be obtained even if the type of the electrode reactant is changed.

DESCRIPTION OF SYMBOLS 11 ... Battery can, 20, 30 ... Winding electrode body, 21, 33 ... Positive electrode, 21A, 33A ... Positive electrode collector, 21B, 33B ... Positive electrode active material layer, 22, 34 ... Negative electrode, 22A, 34A ... Negative electrode collection Electrical body, 22B, 34B ... negative electrode active material layer, 23, 35 ... separator, 36 ... electrolyte layer, 40 ... exterior member.

Claims

Negative electrode active material powder;
A coating layer formed on the negative electrode active material powder;
A binder, and
A negative electrode for a secondary battery, wherein the coating layer includes a hydrocarbon polymer containing at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate, and a carbonate.
The coating layer is a component formed by heat-treating a carboxymethylcellulose-based water-soluble polymer, a component formed by heat-treating a polyacrylic acid-based water-soluble polymer, and a methacrylic acid-based water-soluble polymer The negative electrode for secondary batteries according to claim 1, comprising at least one selected from the group consisting of components formed thereby.
The secondary layer according to claim 1, wherein the coating layer includes at least one selected from the group consisting of a carboxymethylcellulose-based water-soluble polymer, a polyacrylic acid-based water-soluble polymer, and a methacrylic acid-based water-soluble polymer. Battery negative electrode.
The secondary battery negative electrode according to claim 1, wherein the coating layer includes at least one selected from the group consisting of fibrous carbon, vapor-grown carbon fiber, carbon nanotube, graphene, and powdered carbon.
The secondary battery negative electrode according to claim 1, wherein the coating layer contains a carboxylic acid and / or a carboxylate.
The secondary battery negative electrode according to claim 5, wherein the carboxylate is sodium oxalate or lithium oxalate.
The secondary battery negative electrode according to claim 1, wherein the binder is contained in the coating layer.
The negative electrode for a secondary battery according to claim 1, wherein the binder is a polyvinylidene fluoride polymer.
The negative electrode for a secondary battery according to claim 1, wherein the negative electrode active material powder contains a carbon-based material and / or a silicon-based material.
The negative electrode for a secondary battery according to claim 1, comprising N-methylpyrrolidone.
A negative electrode for a secondary battery;
A positive electrode for a secondary battery;
An electrolyte solution,
The negative electrode for a secondary battery comprises a negative electrode active material powder,
A coating layer formed on the negative electrode active material powder;
A binder, and
The secondary battery, wherein the coating layer includes a hydrocarbon polymer containing at least one selected from the group consisting of an ether bond, a carbonyl group, a carboxylic acid, a carboxylate, a carbonate, and a carbonate.
A secondary battery according to claim 11;
A control unit for controlling a usage state of the secondary battery;
A battery pack comprising: a switch unit that switches a use state of the ion secondary battery in accordance with an instruction from the control unit.
A secondary battery according to claim 11;
A conversion unit that converts electric power supplied from the secondary battery into a driving force, and a driving unit that is driven according to the driving force;
And a control unit that controls a usage state of the secondary battery.
A secondary battery according to claim 11;
One or more electrical devices to which power is supplied from the secondary battery;
And a control unit that controls power supply from the secondary battery to the electrical device.
A secondary battery according to claim 11;
And a movable part to which electric power is supplied from the secondary battery.
An electronic device comprising the secondary battery according to claim 11 as a power supply source.