JP2000173587A - Non-aqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte battery using a glass-form solid electrolyte equipped with an enhanced cyclic characteristics, high-rate charge/ discharge characteristics, and high-temp. storage characteristics. SOLUTION: A non-aqueous electrolyte secondary battery is composed of a non-aqueous electrolyte, separator, and a positive and negative electrode capable of storing and emitting lithium, in which the negative electrode consists of composite particles structured so that part or the whole of the peripheral surface of each unclear particle consisting of solid phase A is covered with another solid phase B, wherein the solid phase A contains as least one of silicon or zinc as the constituent element while the phase B is a solid solution or intermetallic compound of silicon or zinc as the phase A constituent element and at least one of the group II elements, transition elements, group XII and XIII elements, and group XIV elements except carbon in the periodic table excluding the above-mentioned constituent elements of the phase A, and the non-aqueous electrolyte is of glass-form solid nature having lithium ion electroconductivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an improvement in the negative electrode material of a non-aqueous electrolyte secondary battery, and to the application of a high oxidation resistant organic solvent as a non-aqueous electrolyte to provide electrochemical characteristics such as charge / discharge capacity and charge / discharge cycle life. The present invention relates to a non-aqueous electrolyte secondary battery used for a portable information terminal, a portable electronic device, a small household power storage device, a motorcycle powered by a motor, an electric vehicle, a hybrid electric vehicle, and the like.

[0002]

2. Description of the Related Art In recent years, lithium secondary batteries used as main power sources for mobile communication devices and portable electronic devices have the characteristics of high electromotive force and high energy density.
A lithium secondary battery using lithium metal as the negative electrode material has a high energy density, but dendrites are deposited on the negative electrode during charging, and the dendrites are cut off during discharging, and fall off from the surface of the bulk metallic lithium negative electrode. , Producing "dead" lithium that cannot contribute to the charge / discharge reaction. Further, there is a possibility that dendrite grows by repeating charge / discharge, breaks through the separator, reaches the positive electrode side, and causes an internal short circuit. In addition, the precipitated dendrite has a high specific activity because of its large specific surface area,
The surface reacts with the solvent in the electrolytic solution to form a solid electrolyte-like interface film lacking electron conductivity. For this reason, the internal resistance of the battery is increased, and particles isolated from the electron conduction network are present, and these are factors that lower the charge / discharge efficiency. For these reasons, lithium secondary batteries using lithium metal as the negative electrode material are:
There were issues with low reliability and short cycle life.

In order to suppress such dendrite, a lithium alloy represented by a lithium-aluminum alloy (Li-Al alloy) or a wood alloy has been proposed as a negative electrode material instead of metallic lithium. In the case of such a metal that can be alloyed with lithium and an alloy containing at least one of these metals, a negative electrode material having a relatively high capacity electrochemically can be obtained in an initial charge / discharge cycle stage. However, the original crystal structure of the skeletal alloy is maintained by repeating alloying with lithium and elimination of lithium by charge and discharge, but a phase change occurs or differs from the skeletal alloy of the element. It may change to a crystal structure. In this case, particles of the metal or alloy, which is the host material of lithium as the active material, undergo expansion and contraction, and as the charge and discharge cycle progresses, stress is applied to the crystal grains. As a result, falling off from the electrode plate proceeds. As the particles become finer, the grain boundary resistance and the grain boundary contact resistance increase. As a result, resistance polarization at the time of charge / discharge increases, and at the time of voltage-controlled charging, the depth of charge becomes shallow, and the amount of charged electricity is small. On the other hand, during discharge, a voltage drop occurs due to resistance polarization, and the discharge end voltage is quickly reached. Therefore, it is difficult for both the charge and discharge capacity and the cycle characteristics to be excellent.

At present, a carbon material capable of occluding and releasing lithium ions has been used as a negative electrode material in place of lithium metal, and has been put to practical use. Normally, metallic lithium does not precipitate on the carbon material negative electrode, so there is no problem of internal short circuit due to dendrite. However, the theoretical capacity of graphite, one of the carbon materials, is 372 mAh / g, which is 10% of the theoretical capacity of Li metal alone.
It is as small as one-third. Further, as other compound active material materials, diniobium pentoxide (Nb ₂ O ₅ ), titanium disulfide (Ti
S ₂ ), molybdenum dioxide (MoO ₂ ), lithium titanate (Li _4/3 Ti _5/3 O ₄ ) and the like. These materials are chemically stable, do not generate dendrites, and have remarkable cycling characteristics compared to metallic lithium, which has high chemical activity, because lithium is retained in the host material in an ionized state. It has been improved and carbon-based materials have been put to practical use.

As other negative electrode materials, a simple metal material and a simple nonmetal material which form a compound with lithium are known. For example, the composition formulas of the compounds containing the most lithium of silicon (Si) and zinc (Zn) are Li ₂₂ Si ₅ and LiZn, respectively. In this range, metallic lithium does not usually precipitate, so the problem of internal short circuit due to dendrites is Absent. The electrochemical capacities between these compounds and the individual materials are 4199 mAh / g and 410 mAh / g, respectively, which are both larger than the theoretical capacity of graphite.

In addition to a simple metal material and a simple non-metal material forming a compound with lithium, as a compound negative electrode material, Japanese Patent Application Laid-Open No. 7-240201 discloses a non-ferrous metal silicide comprising a transition element. No. 63651 discloses an intermetallic compound containing a Group 4B element and at least one of P and Sb, and has a crystal structure of CaF ₂ type, ZnS type, or AlL.
Negative electrode materials made of any of the iSi type have been proposed.

On the other hand, as a solvent of an electrolytic solution used for a non-aqueous electrolyte battery, propylene carbonate (PC), ethylene carbonate (E
Cyclic carbonate represented by C) or diethyl carbonate (DE
C), a chain carbonate represented by dimethyl carbonate (DMC), γ-butyrolactone (GBL), γ-valerolactone (GV
L) represented by cyclic carboxylic acid esters, chain ethers such as dimethoxymethane (DMM) and 1,3-dimethoxypropane (DMP), and cyclic esters such as tetrahydrofuran (THF) and 1,3-dioxolane (DOL). Often used.

When applied to a non-aqueous electrolyte secondary battery, a material having a high electric conductivity is desirable. For this purpose, a solvent having a high relative dielectric constant and a low viscosity is preferably used. However, a high relative dielectric constant is nothing less than a strong polarity, that is, a high viscosity. For this purpose, propylene carbonate (dielectric constant ε = 6
5) High dielectric constant solvent such as 5) and 1,2-dimethoxyethane (DM
E, ε = 7.2) and is often used in combination with a low dielectric constant solvent represented by E.

The electrolyte used for the non-aqueous electrolyte battery is obtained by dissolving a supporting electrolyte having a concentration of about 1 mol in the above-mentioned solvent. As the supporting electrolyte, lithium perchlorate (LiClO ₄ ), lithium borofluoride (LiBF ₄ ), an inorganic acid anion lithium salt represented by lithium phosphorus fluoride (LiPF ₆ ), and lithium trifluoromethane sulfonate (LiSO ₃
Organic acid anion lithium salts such as CF ₃ ) and lithium bistrifluoromethanesulfonimide ((CF ₃ SO ₂ ) ₂ NLi) are used.

[0010]

However, the negative electrode materials having higher capacities than the above-mentioned carbon materials have the following problems, respectively.

A single metal material and a single nonmetallic negative electrode material which form a compound with lithium commonly have poorer charge / discharge cycle characteristics than a carbon negative electrode material. The reason is not clear, but I think as follows.

For example, silicon has its crystallographic unit cell.
(Cubic, space group Fd-3m) containing 8 silicon atoms
I have. Converted from lattice constant a = 0.5420 nm, unit cell volume
Is 0.1592nm^ThreeAnd the volume occupied by one silicon atom is 19.
9 × 10^-3nm^ThreeIt is. From the phase diagram of the silicon-lithium binary system
Judging, electrochemical compound with lithium at room temperature
In product formation, silicon and the compound Li₁₂Si₇
It is considered that these two phases coexist. Li₁₂Si₇of
56 crystallographic unit cells (rhombic, space group Pnma)
Contains a silicon atom. Its lattice constant a = 0.8610n
Converted from m, b = 1.9737 nm, c = 1.4341 nm, unit lattice
Product is 2.4372nm^ThreeAnd the volume per silicon atom
(The unit cell volume is divided by the number of silicon atoms in the unit cell.
Value) is 43.5 × 10 ^-3nm^ThreeIt is. From this value,
Element to compound Li₁₂Si₇The volume of the material
It will expand 2.19 times. Silicon and compound Li₁₂Si₇
In the coexistence of two phases with
₁₂Si₇These volume differences are large due to the
Large strains, cracks easily, and fine particles
It can be easy to become. More electrochemical lithium
When the compound formation reaction with the
Li-rich compound_{twenty two}Si_FiveIs generated. Li_{twenty two}Si_FiveCrystal
The unit cell (cubic, space group F23) has 80
Contains an iodine atom. From its lattice constant a = 1.8750 nm
Converted, the unit cell volume is 6.5918 nm^ThreeAnd the silicon source
Volume per child (unit cell volume is
82.4 × 10)^-3nm^ThreeIt is. This value
Is 4.14 times that of elemental silicon, and the material is greatly expanded.
You. In the discharge reaction for the negative electrode material, the compound
The material shrinks as the reaction decreases. This
Since the volume difference between charging and discharging is large as in
Large strain occurs, cracks occur and particles become finer
it is considered as. In addition, there is a space between these miniaturized particles
The electron conduction network is disrupted and the electrochemical
The part that cannot participate in the reaction increases and the charge / discharge capacity decreases.
It is considered to be.

[0013] Zinc contains two zinc atoms in a crystallographic unit cell (hexagonal, space group P63 / mmc).
Lattice constant a = 0.2665nm, in terms of c = 0.4947nm, unit cell volume is 0.030428nm ^3, the volume occupied by one zinc atom is 15.2 × 10 ^-3 nm ^3. Judging from the phase diagram of the zinc-lithium binary system, a lithium-rich compound LiZn is finally produced through several compounds. The crystallographic unit cell of LiZn (cubic, space group Fd-3m) contains eight zinc atoms. Converted from the lattice constant a = 0.6209 nm, the unit cell volume is 0.2394 nm ³ , and the volume per zinc atom (the value obtained by dividing the unit cell volume by the number of zinc atoms in the unit cell) is 29.9 × 10 ^-3 nm ^3. This value is 1.97 times that of elemental zinc, and the material expands.

As described above, both tin and zinc have a large change in the volume of the negative electrode material due to the charge and discharge reaction, similarly to silicon, and the material repeatedly undergoes a change in a state in which two phases having a large volume difference coexist. It is considered that the particles become finer. Finely divided material creates spaces between particles,
It is considered that the electron conduction network is disconnected, the portion that cannot participate in the electrochemical reaction increases, and the charge / discharge capacity decreases.

That is, the large volume change common to the negative electrode materials of a simple metal material and a simple non-metal material forming a compound with lithium, and the structural change due to this, are the reasons why the charge / discharge cycle characteristics are poor as compared with the carbon negative electrode material. I guess.

On the other hand, unlike the above-mentioned simple material, it is composed of a silicide of a non-ferrous metal comprising a transition element or an intermetallic compound containing at least one of a Group 4B element and P or Sb, and its crystal structure is CaF ₂ type, ZnS A negative electrode material of any one of the negative electrode type and the AlLiSi type has been proposed as a negative electrode material having improved cycle life characteristics in JP-A-7-240201 and JP-A-9-63651, respectively.

Batteries using a non-ferrous metal silicide negative electrode material comprising a transition element disclosed in Japanese Patent Application Laid-Open No. 7-240201 were used in the first cycle, the 50th cycle, and the 100th cycle shown in Examples and Comparative Examples. From the battery capacity, the charge-discharge cycle characteristics are improved as compared with the lithium metal anode material, but the battery capacity is increased by only about 12% at the maximum as compared with the natural graphite anode material. Therefore, although not explicitly stated in the specification, it is considered that the non-ferrous metal silicide negative electrode material composed of a transition element has not been significantly increased in capacity as compared with the graphite negative electrode material.

Further, the materials disclosed in Japanese Patent Application Laid-Open No. 9-63651 have improved charge-discharge cycle characteristics as compared with the Li-Pb alloy negative electrode material in Examples and Comparative Examples, and have a higher performance than the graphite negative electrode material. It has been shown to be of high capacity. However, the discharge capacity is remarkably reduced in the charge / discharge cycles of 10 to 20 cycles, and even for Mg ₂ Sn which is considered to be the best, the capacity is reduced to about 70% of the initial capacity after about 20 cycles.

When metallic lithium is used as the negative electrode, the electrolytic solution in contact with the negative electrode is exposed to an extremely strong reducing atmosphere, and the electrolytic solution reacts with the metallic lithium and easily undergoes reductive decomposition. Furthermore, among the Li-Al alloys and the like, when an alloy mainly composed of lithium is used for the negative electrode, the electrode potential of the negative electrode is almost equal to that of metallic lithium, and the reductive decomposition of the electrolytic solution occurs almost in the same manner. As described above, as described above, the negative electrode active material is miniaturized by repeated charging and discharging, and falls off from the electrode plate. Further, when a metal other than lithium is mainly used in the alloy composition, the electrode potential of the negative electrode is lower than that of metallic lithium or a lithium alloy,
It is possible to use an electrolyte solution that is noble and undergoes the reductive decomposition described above. However, when these alloys are alloyed with lithium, they become harder and more brittle than alloys mainly composed of lithium, and the alloys are extremely finely divided.
Drops from the plates are inevitable.

Further, when a solvent such as ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propylene carbonate, γ-butyrolactone, or γ-valerolactone is used in a system using metal lithium and a lithium alloy as a negative electrode, the charge is reduced. When the battery in the state is stored at a high temperature, the electrolytic solution is decomposed and gas is generated, or when the battery is repeatedly charged and discharged, the gasification reaction of the electrolytic solution is performed in parallel with the charge and discharge reaction of the negative electrode. Cause the charge and discharge efficiency to decrease,
As a result, there is a problem that the cycle characteristics deteriorate.

On the other hand, when a graphite-based carbon material is used for the negative electrode material and an electrolyte using propylene carbonate is applied,
Decomposition of the electrolyte occurs at a more noble potential than on metallic lithium, so that lithium ions do not intercalate between graphite layers and do not operate as a battery. Therefore, currently available lithium secondary batteries using a graphite-based negative electrode material often use an electrolyte containing ethylene carbonate. However, ethylene carbonate has a melting point of 37 ° C., which is higher than room temperature. Therefore, at low temperatures, the lithium ion conductivity of the electrolytic solution rapidly decreases, and the charge / discharge characteristics deteriorate.

When an inorganic compound material such as titanium disulfide is used as the negative electrode active material, the intercalation and deintercalation occur at a potential sufficiently higher than that of metallic lithium or a lithium alloy. for that reason,
The electrolyte does not undergo reductive decomposition even when it comes into contact with the electrolytic solution, and the electrolytic solution does not disturb the insertion / desorption of lithium, unlike propylene carbonate, which could not be used with graphite-based materials, The range of choice of liquid is expanded. However, since the potential of these inorganic compound material negative electrodes is noble, the battery voltage is low, which is disadvantageous for increasing the energy density.

As for the supporting electrolyte, lithium perchlorate, lithium borofluoride and lithium phosphorus fluoride all have a problem in thermal stability, and at the same time, the fluorine-containing inorganic anion salt (for example, phosphorus In the case of lithium fluoride, it has a problem that it reacts with water slightly contained in the electrolytic solution (shown in Chemical Formulas 1 to 3) and decomposes.

[0024]

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[0025]

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[0026]

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When a lithium ion conductive glassy solid electrolyte is used as the non-aqueous electrolyte to form an all-solid battery, the solid electrolyte powder is added to the electrode in order to secure and maintain the ion conductivity in the electrode. Need to be mixed. Such an electrode is hard and brittle, cannot absorb the expansion and contraction caused by the charge and discharge of the electrode material, and does not shrink due to lack of elasticity while the entire electrode expands.
As a result, there is a problem that poor bonding between particles occurs, the number of electrode material particles that do not contribute to charge and discharge increases, and as a result, battery characteristics deteriorate.

[0028]

According to the present invention, there is provided a composite particle wherein the whole or a part of the periphery of a core particle comprising a solid phase A is coated with a solid phase B, wherein the solid phase A is at least one of silicon and zinc. Is a constituent element of the periodic table, and the solid phase B is any of silicon and zinc as constituent elements of the solid phase A and, except for the constituent elements, a Group 2 element, a transition element, a Group 12 element, and a Group 13 element of the periodic table. , And a material that is a solid solution or an intermetallic compound with at least one element selected from the group consisting of Group 14 elements excluding carbon, so that the solid phase A has a higher capacity and A non-aqueous electrolyte contains at least lithium sulfide as the first component, and silicon sulfide and sulfide as the second component, using a negative electrode material with excellent charge-discharge cycle characteristics by playing a role in suppressing expansion and contraction caused by discharge. Phosphorus and sulfur One or more compounds selected from the group consisting of boron hydride and one or more compounds selected from the group consisting of lithium phosphate, lithium sulfate, lithium borate and lithium silicate as the third component When using a lithium ion conductive glassy solid electrolyte synthesized from a plurality of compounds, it was found that gas generation was extremely low during high-temperature storage, and that the charge and discharge efficiency of the negative electrode did not decrease during repeated charge and discharge. The object of the present invention is to provide a novel non-aqueous electrolyte secondary battery that can be used in a wide temperature range, has a high energy density, has a small decrease in discharge capacity due to repeated use of the battery, and has excellent high-rate charge / discharge characteristics. And

Since the solid phase A of the negative electrode material of the present invention contains at least one of silicon and zinc having a high capacity as a constituent element, it is considered that the solid phase A mainly contributes to an increase in the charge / discharge capacity. Further, it is considered that the solid phase B which covers the whole or a part of the periphery of the core particles composed of the solid phase A contributes to the improvement of the charge / discharge cycle characteristics. Further, lithium is hardly absorbed in the solid phase B of the negative electrode material, but is absorbed only in the solid phase A. Therefore, only the solid phase B containing no active lithium contacts the electrolyte in the negative electrode material. Therefore, it is considered that decomposition of the electrolyte is unlikely to occur even when the phase contacts the electrolyte.

On the other hand, the lithium ion conductive glassy solid electrolyte used in the present invention has a glass transition temperature of 300 ° C. or more,
Since the crystallization temperature is extremely high at 400 ° C. or higher, it is considered that gas generation and characteristic deterioration during high-temperature storage are extremely small. Furthermore, since the solid electrolyte is glassy, the conduction path of lithium ions is:
Unlike a crystalline solid electrolyte, it has anisotropy and can obtain conductivity on any surface of the solid electrolyte powder. Therefore, there is an advantage that the contact surface can be freely formed when the powdered electrode material is mixed.

The addition of the oxoacid salt of the third component makes the solid electrolyte extremely high in oxidation-resistant decomposition voltage as compared with the non-added one, and has a voltage of about 10 V. This is because, in the case of no addition, the glass skeleton consists of only -Si-S-Si-, whereas the addition of an oxoacid salt locally has a stronger Si-O bond than the Si-S bond. -O-Si-
We believe that the skeleton will be mixed. Therefore,
When the solid electrolyte is used, the positive electrode material may be a material that generates a high voltage of 4 V or more.

In addition, when the oxo acid salt is not added, there is a problem that the impedance at the junction interface increases with time when the oxo acid salt is brought into contact with the metal lithium. Since the increase in the interface impedance is suppressed even in the case of contact, there is also a favorable effect that stability against contact with metallic lithium is also improved.

By combining the above-described negative electrode material and the solid electrolyte, reliability in a wide temperature range can be ensured, and a high-capacity battery excellent in cycle characteristics can be provided.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION A positive electrode and a negative electrode used in the present invention are a mixture layer containing a conductive agent, a binder and the like in a positive electrode active material or a negative electrode material capable of electrochemically and reversibly inserting and releasing lithium ions. Is applied to the surface of the current collector.

The negative electrode material used in the present invention is a composite particle in which the whole or a part of the periphery of the core particle composed of the solid phase A is coated with the solid phase B, and the solid phase A contains at least one of silicon and zinc. The solid phase B includes any of silicon and zinc as the constituent elements of the solid phase A, and, except for the constituent elements, a group 2 element of the periodic table, a transition element,
A solid solution with at least one element selected from the group consisting of Group 13 elements, Group 13 elements, and Group 14 elements excluding carbon, or a material that is an intermetallic compound (hereinafter, referred to as “composite particles”).

As one of the methods for producing composite particles used in the present invention, a melt of the charged composition of each element constituting the composite particles is prepared by a dry spray method, a wet spray method, a roll quenching method and a rotating electrode method. Rapid cooling and solidification by such as
There is a method of performing heat treatment at a temperature lower than the solidus temperature of the solid solution or the intermetallic compound determined by the charged composition. By rapid solidification of the melt, solid phase A particles as core particles and solid phase B covering the entire surface or a part of the periphery of the solid phase A particles are precipitated.
The purpose of the present invention is to increase the uniformity of the composite particles, but the composite particles according to claim 1 can be obtained even without heat treatment. In addition, any method other than the above-mentioned cooling method can be used as long as it can sufficiently cool.

As another manufacturing method, an adhesion layer made of an element other than the elements contained in the solid phase A necessary for forming the solid phase B is formed on the surface of the powder of the solid phase A.
There is a method of performing heat treatment at a temperature lower than the solidus temperature of the solid solution or the intermetallic compound determined by the charged composition. By this heat treatment, the component elements in the solid phase A diffuse into the adhesion layer, and the solid phase B is formed as a coating layer. The adhesion layer can be formed by a plating method or a mechanical alloying method. In addition, any method capable of forming an adhesion layer can be used. In the mechanical alloying method, heat treatment may not be required.

The invention according to claim 1 of the present invention is characterized in that the material obtained as described above is used for a negative electrode, and a lithium ion conductive glassy solid electrolyte is used as a high oxidation resistant organic solvent as an electrolyte. Things.

The composite particles are high in capacity, have a small decrease in discharge capacity due to repeated charge / discharge, and have excellent high rate charge / discharge characteristics. The negative electrode is composed of a positive electrode capable of inserting and extracting lithium and an electrolyte. By using a lithium-ion conductive glassy solid electrolyte for a battery, a battery having high capacity, high energy density, and high reliability in a wide temperature range is achieved.

According to a second aspect of the present invention, the lithium ion conductive glassy solid electrolyte according to the first aspect contains at least lithium sulfide as a first component, and silicon sulfide, phosphorus sulfide and One or more compounds selected from the group consisting of boron sulfide and one or more compounds selected from the group consisting of lithium phosphate, lithium sulfate, lithium borate and lithium silicate as the third component This is a lithium ion conductive glassy solid electrolyte synthesized from a plurality of compounds.

When a lithium ion conductive glassy solid electrolyte is used to form an all-solid battery, it is necessary to disperse the solid electrolyte in the electrodes to secure and maintain an ion conduction path.

At this time, as the lithium ion conductive glassy solid electrolyte to be mixed, the smaller the particle size, the better.
0.02 to 30 μm is preferred. More preferably,
0.02 to 10 μm. The mixing ratio with the electrode material is not particularly limited, but is preferably 5 to 80% by weight, particularly preferably 5 to 30% by weight, based on the electrode material.

Further, the binder used in forming the solid electrolyte sheet used in the present invention may be either a thermoplastic resin or a thermosetting resin. Preferred binders in the present invention are, for example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE),
Polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer (FE
P), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), vinylidene fluoride
Hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE resin), polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymer Copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer, vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoro Ethylene copolymer, ethylene-acrylic acid copolymer or (Na ⁺ ) ion crosslinked product of the above material, ethylene-methacrylic acid copolymer or (Na ⁺ ) ion crosslinked product of the above material, ethylene-methyl acrylate copolymer Coalescing or said Fee (Na ⁺⁾ ion crosslinked body, an ethylene - can be exemplified (Na ⁺⁾ ion crosslinked product of methyl methacrylate copolymer or. Particularly, among these, polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) are most preferable.

The conductive agent for a negative electrode used in the present invention may be any material as long as it is an electron conductive material. For example, graphites such as natural graphite (flaky graphite, etc.) and artificial graphite, carbon blacks such as acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, metal fiber, etc. Conductive fibers, metal powders such as carbon fluoride, copper and nickel, and organic conductive materials such as polyphenylene derivatives, and the like, alone or as a mixture thereof. Among these conductive agents, artificial graphite, acetylene black and carbon fiber are particularly preferred. The amount of the conductive agent is not particularly limited, but is preferably 1 to 50% by weight, and particularly preferably 1 to 30% by weight. In addition, since the negative electrode material of the present invention itself has electronic conductivity, it is possible to function as a battery without adding a conductive agent.

The binder for the negative electrode used in the present invention may be either a thermoplastic resin or a thermosetting resin. Preferred binders in the present invention include, for example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), styrene butadiene rubber, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene Ethylene-perfluoroalkyl vinyl ether copolymer (PF
A), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene copolymer (ETFE resin), polychlorotrifluoroethylene (PC
TFE), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer (ECTFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer , Vinylidene fluoride-perfluoromethylvinyl ether-tetrafluoroethylene copolymer, ethylene-acrylic acid copolymer or (Na ⁺ ) ion cross-linked product of the above material, ethylene-methacrylic acid copolymer or (Na ⁺ ) Ion crosslinked product, ethylene-methyl acrylate copolymer or (Na ⁺ ) ion crosslinked product of the above material, ethylene-methyl methacrylate copolymer or (Na ⁺ ) ion crosslinked product of the above material, and the like. These materials can be used alone or as a mixture. Further, among these materials, more preferred materials are styrene-butadiene rubber, polyvinylidene fluoride, ethylene-acrylic acid copolymer or (Na ⁺ ) ion crosslinked product of the above-mentioned material, ethylene-methacrylic acid copolymer or the above-mentioned material. (Na ⁺ ) ion crosslinked product, ethylene-methyl acrylate copolymer or (Na ⁺ ) ion
⁺ ) Ion crosslinked product, ethylene-methyl methacrylate copolymer or (Na ⁺ ) ion crosslinked product of the above-mentioned material.

As the current collector for the negative electrode used in the present invention, any collector may be used as long as it does not cause a chemical change in the constructed battery. For example, in addition to stainless steel, nickel, copper, titanium, carbon, conductive resin, and the like, a material obtained by treating the surface of copper or stainless steel with carbon, nickel, or titanium is used. Particularly, copper or a copper alloy is preferable. The surface of these materials can be oxidized and used. In addition, it is desirable to make the current collector surface uneven by surface treatment. As the shape, in addition to a foil, a film, a sheet, a net, a punched material, a lath body, a porous body, a foamed body, a molded body of a fiber group, and the like are used. The thickness is not particularly limited, but 1 to
Those having a size of 500 μm are used.

As the positive electrode material used in the present invention, a lithium-containing compound can be used. For example, Li _x CoO
₂ , Li _x NiO ₂ , Li _x MnO ₂ , Li _x Co _y Ni _1-y O ₂ , Li _x Co _y M _1-y O _z , Li _x
Ni _{1- y} M _y O _z , Li _x Mn ₂ O ₄ , Li _x Mn _2-y M _y O ₄ (M = Na, Mg, Sc, Y, Mn,
Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and at least one of B), (where 0 <x ≦ 1.2, 0 ≦ y ≦ 0.9, 2.0 ≦ z ≦ 2.3). Here, the above-mentioned x value is a value before the start of charge / discharge, and increases / decreases due to charge / discharge. However, other positive electrode active materials such as a transition metal chalcogenide, a lithium compound of vanadium oxide, a lithium compound of niobium oxide, a conjugated polymer using an organic conductive material, and a Chevrel phase compound can also be used. It is also possible to use a mixture of a plurality of different positive electrode active materials. The average particle size of the positive electrode active material particles is not particularly limited, but 1 to 30 μm.
m is preferable.

The conductive agent for the positive electrode used in the present invention may be any electronic conductive material which does not cause a chemical change at the charge / discharge potential of the positive electrode material used. For example, graphites such as natural graphite (flaky graphite, etc.), artificial graphite, acetylene black, Ketjen black, channel black, furnace black, lamp black,
Carbon blacks such as thermal black, carbon fiber,
Conductive fibers such as metal fibers, metal powders such as carbon fluoride, copper, nickel, aluminum and silver, zinc oxide,
A conductive whisker such as potassium titanate, a conductive metal oxide such as titanium oxide, an organic conductive material such as a polyphenylene derivative, or the like can be included alone or as a mixture thereof. Among these conductive agents, artificial graphite, acetylene black and nickel powder are particularly preferred. The amount of the conductive agent is not particularly limited,
It is preferably from 1 to 50% by weight, particularly preferably from 1 to 30% by weight. For carbon and graphite, 2 to 15% by weight is particularly preferred.

The binder for the positive electrode used in the present invention may be either a thermoplastic resin or a thermosetting resin. Preferred binders in the present invention include, for example, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoroethylene copolymer, tetrafluoroethylene-hexafluoropropylene Copolymer (FEP), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, ethylene-tetrafluoroethylene Copolymer (ETFE resin), polychlorotrifluoroethylene (PCTFE), vinylidene fluoride-pentafluoropropylene copolymer, propylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer ECTFE), vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene copolymer, vinylidene fluoride - perfluoromethyl vinyl ether - tetrafluoroethylene copolymer, ethylene - acrylic acid copolymer or (Na ⁺⁾ ions A crosslinked product, an ethylene-methacrylic acid copolymer or a (Na ⁺ ) ion crosslinked product of the above material, ethylene-
Examples thereof include a methyl acrylate copolymer or a (Na ⁺ ) ion crosslinked product of the above material, an ethylene-methyl methacrylate copolymer or a (Na ⁺ ) ion crosslinked product of the above material. Particularly, among these, polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) are most preferable.

The current collector for the positive electrode used in the present invention may be any electronic conductor that does not cause a chemical change in the charge and discharge potential of the positive electrode material used. For example, in addition to stainless steel, aluminum, titanium, carbon, conductive resin, and the like, a material obtained by treating the surface of aluminum or stainless steel with carbon or titanium is used. Particularly, aluminum or an aluminum alloy is preferable. The surface of these materials can be oxidized and used. In addition, it is desirable to make the current collector surface uneven by surface treatment. As the shape, in addition to a foil, a film, a sheet, a net, a punched material, a lath body, a porous body, a foamed body, a fiber group, a molded body of a nonwoven fabric body, or the like is used. The thickness is not particularly limited, but a thickness of 1 to 500 μm is used.

In the electrode mixture, a filler, a dispersant, an ion conductor, a pressure enhancer and other various additives can be used in addition to the conductive agent and the binder. As the filler, any fibrous material that does not cause a chemical change in the configured battery can be used. Usually, fibers such as olefin-based polymers such as polypropylene and polyethylene, glass, and carbon are used. The amount of the filler added is not particularly limited, but is preferably 0 to 30% by weight.

The structure of the negative electrode plate and the positive electrode plate in the present invention is as follows.
It is preferable that the negative electrode mixture surface exists at least on the surface opposite to the positive electrode mixture surface.

The shape of the battery can be any of a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, a square type, and a large type used for electric vehicles.

Further, the non-aqueous electrolyte secondary battery of the present invention can be used for a portable information terminal, a portable electronic device, a small household power storage device,
The present invention can be used for a motorcycle, an electric vehicle, a hybrid electric vehicle, and the like, but is not particularly limited thereto.

[0055]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

(Example 1) Method for producing negative electrode material Table 1 shows the components (simple element, intermetallic compound) of solid phase A and solid phase B of the negative electrode material (material A to material L) used in this example. , Solid solution), element ratio at the time of preparation, melting temperature, and solidus temperature. In this embodiment, a specific manufacturing method will be described below.

A powder or a block of each element constituting the negative electrode material is charged into a dissolving tank at a charging ratio shown in Table 1,
It was melted at the melting temperature shown in (Table 1), and the melt was quenched and solidified by a roll quenching method to obtain a solidified product. Subsequently, the solidified product was subjected to a heat treatment for 20 hours in an inert atmosphere at a temperature lower by about 10 ° C. to 50 ° C. than the solidus temperature of the solid solution or the intermetallic compound determined by the charged composition shown in Table 1. This heat-treated product was pulverized with a ball mill and classified with a sieve to obtain materials A to L in the form of particles of 45 μm or less. From these electron microscopic observation results, it was confirmed that the entire surface or a part of the periphery of the solid phase A particles was covered with the solid phase B.

[0058]

[Table 1]

Method for Producing Solid Electrolyte and Solid Electrolyte Sheet A lithium ion conductive glassy solid electrolyte was produced as follows.

A mixture of lithium phosphate, lithium sulfide and silicon disulfide in a molar ratio of 1:63:36 was put into a glassy carbon crucible and dried at 1000 ° C. in a dry nitrogen atmosphere.
The melt was melted for 2 hours, and the melt was quenched with a twin roller to prepare. The obtained solid electrolyte glass was pulverized to obtain a solid electrolyte powder. The result of synthesizing a lithium ion conductive glassy solid electrolyte of a combination of other raw materials in the same way,
It is shown in (Table 2). In the table, the ionic conductivity shows the result measured by the AC impedance method, and the oxidation-resistant decomposition voltage shows the result measured by the potential scanning method.

[0061]

[Table 2]

Next, the solid electrolyte powder 98 obtained above is obtained.
2% by weight of polytetrafluoroethylene (PTFE)
Was added and mixed sufficiently in a mortar to form an elastic body, which was rolled with a roller to obtain a solid electrolyte sheet.

FIG. 1 is a longitudinal sectional view of a cylindrical battery according to the present invention. The positive electrode plate 5 and the negative electrode plate 6 are spirally wound a plurality of times via the solid electrolyte sheet 7 and housed in the battery case 1. Then, a positive electrode lead 5 a is drawn out from the positive electrode plate 5 and connected to the sealing plate 2, and a negative electrode lead 6 a is drawn out from the negative electrode plate 6 and connected to the bottom of the battery case 1. For the battery case and the lead plate, a metal or an alloy having electronic conductivity can be used. For example, iron, nickel,
Metals such as titanium, chromium, molybdenum, copper, and aluminum or alloys thereof are used. In particular, the battery case is preferably made of a stainless steel plate or an Al-Mn alloy plate, and the positive electrode lead is most preferably aluminum and the negative electrode lead is preferably nickel. Further, as the battery case, various types of engineering plastics and a combination thereof with a metal can be used to reduce the weight. Reference numeral 8 denotes an insulating ring provided on the upper and lower portions of the electrode plate group 4, respectively.
Then, a battery can is formed using the sealing plate. At this time,
Safety valves can be used as sealing plates. In addition to the safety valve, various conventionally known safety elements may be provided. For example, a fuse, a bimetal, a PTC element, or the like is used as the overcurrent prevention element. In addition to the safety valve, as a countermeasure against an increase in the internal pressure of the battery case, a method of making a cut in the battery case, a gasket cracking method, a sealing plate cracking method, or a cutting method with a lead plate can be used. Further, the charger may be provided with a protection circuit incorporating measures for overcharging and overdischarging, or may be connected independently. As a method for welding the cap, the battery case, the sheet, and the lead plate, a known method (eg, DC or AC electric welding, laser welding, ultrasonic welding) can be used. A conventionally known compound or mixture such as asphalt can be used as the sealing agent for closing.

The negative electrode plate 6 is composed of 60% by weight of the obtained negative electrode material, 15% by weight of a lithium ion conductive glassy solid electrolyte powder, 20% by weight of a carbon powder as a conductive agent, and polyvinylidene fluoride as a binder. A resin was mixed with 5% by weight, and these were dispersed in dehydrated N-methylpyrrolidinone to prepare a slurry. The slurry was applied on a negative electrode current collector made of copper foil, dried, and then rolled.

On the other hand, the positive electrode plate 5 was composed of 15% by weight of a lithium ion conductive glassy solid electrolyte powder and 10% by weight of a carbon powder of a conductive agent with respect to 70% by weight of lithium cobalt oxide powder.
And 5% by weight of polyvinylidene fluoride resin as a binder, and these are dispersed in dehydrated N-methylpyrrolidinone to prepare a slurry, applied on a positive electrode current collector made of aluminum foil, dried, and then rolled. Produced.

As described above, (Table 3) to (Table 14)
As shown in Table 1, batteries 1 to 168 using the materials A to L in Table 1 as negative electrodes and the materials a to l in Table 2 as solid electrolytes were produced. The manufactured cylindrical battery had a diameter of 18 mm and a height of 650 mm. These batteries were charged at a constant current of 100 mA until the voltage reached 4.1 V, and then a charge / discharge cycle of discharging the battery to 2.0 V at a constant current of 100 mA was repeated. The charge / discharge was repeated up to 100 cycles, and the ratio of the discharge capacity at the 100th cycle to the initial discharge capacity was defined as the capacity retention ratio (Table 3) to (Table 1).
4).

Further, (Table 3) to (Table 14) show that the same configuration was used at a constant current of 100 mA until the battery was charged to 4.1 V and then temporarily discharged to 2.0 V. After checking again, the ratio of the discharge capacity after storage to the discharge capacity before storage as the capacity retention ratio when the battery charged to 4.1 V under the same conditions was stored at 85 ° C. for 60 days, and the battery after storage A gas was collected in liquid paraffin, but gas could not be collected from any of the batteries.

[0068]

[Table 3]

[0069]

[Table 4]

[0070]

[Table 5]

[0071]

[Table 6]

[0072]

[Table 7]

[0073]

[Table 8]

[0074]

[Table 9]

[0075]

[Table 10]

[0076]

[Table 11]

[0077]

[Table 12]

[0078]

[Table 13]

[0079]

[Table 14]

When the solid phase A is Si, the elements constituting the negative electrode material used in this example are Mg as a Group 2 element, Co and Ni as transition elements, Zn as a Group 12 element, and Al as a Group 13 element. Although Sn was used as a group 14 element, similar effects were obtained by using elements of each group other than these. When the solid phase A is Zn, Mg is used as a Group 2 element, and Cu is used as a transition element.
And V, Cd as a Group 12 element, Al as a Group 13 element,
Ge was used as a Group 14 element, but similar effects were obtained by using elements of each group other than these.

Further, the charge ratio of the constituent elements of the negative electrode material is not particularly limited, and the phases become two phases.
One phase (solid phase A) is mainly a phase mainly composed of Sn and Zn, and another phase (solid phase B) may be in a state of covering a part or the whole thereof. The charge composition is not particularly limited. Phase B not only consists of the solid solution and intermetallic compound shown in Table 1, but also each solid solution,
This includes the case where the element constituting the intermetallic compound and other elements are present in trace amounts.

The composition of the lithium ion conductive glassy solid electrolyte used in this example is not particularly limited, and the obtained substance is glassy and exhibits lithium ion conductivity. Further, it is only necessary that an oxidative decomposition voltage of 5 V or more can be obtained, and the charged composition of the lithium ion conductive glassy solid electrolyte in this example is not particularly limited.

[0083]

As described above, according to the present invention, a non-aqueous solution having a higher capacity and superior cycle characteristics, high rate charge / discharge characteristics, and high-temperature storage characteristics than those obtained by using a conventional carbon material as a negative electrode material. An electrolyte secondary battery is obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a cylindrical battery according to an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery case 2 Sealing plate 3 Insulating packing 4 Electrode group 5 Positive electrode plate 5a Positive electrode lead 6 Negative electrode plate 6a Negative electrode lead 7 Solid electrolyte sheet 8 Insulation ring

Continuing on the front page (72) Inventor: Harushima Shimamura 1006, Kazuma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (Reference) 5H003 AA01 AA03 AA04 BB02 BB05 BC01 BC05 5H014 AA01 BB08 CC01 EE05 EE10 5H017 AA03 AS02 CC01 CC03 CC25 CC28 EE01 EE04 EE05 5H029 AJ00 AJ02 AJ05 AK03 AL11 AM12 BJ02 DJ14 DJ14

Claims (2)

[Claims] 1. A non-aqueous electrolyte secondary battery including a non-aqueous electrolyte, a separator, and a positive electrode and a negative electrode capable of inserting and extracting lithium, wherein the negative electrode is formed on the entire surface around the core particles composed of solid phase A or A part thereof is a composite particle coated with a solid phase B, wherein the solid phase A includes at least one of silicon and zinc as constituent elements, and the solid phase B is any of silicon and zinc which are constituent elements of the solid phase A. A solid solution with at least one element selected from the group consisting of Group 2 elements, transition elements, Group 12 and Group 13 elements, and Group 14 elements excluding carbon except for the above-mentioned constituent elements; A non-aqueous electrolyte secondary battery using a compound material and a lithium ion conductive glassy solid electrolyte as a non-aqueous electrolyte. 2. The lithium ion conductive glassy solid electrolyte according to claim 1, which comprises at least lithium sulfide as a first component and silicon sulfide, phosphorus sulfide, and boron sulfide as a second component. It is synthesized from one or more compounds selected and a plurality of compounds of one or more compounds selected from the group consisting of lithium phosphate, lithium sulfate, lithium borate, and lithium silicate as the third component. The non-aqueous electrolyte secondary battery according to claim 1, wherein the non-aqueous electrolyte secondary battery is a lithium ion conductive glassy solid electrolyte.