JPH08264178A - Nonaqueous secondary battery - Google Patents

Abstract

PURPOSE: To improve a discharge capacity, a charge/discharge cycle characteristic, and safety by using an amorphous compound, which is obtained by mixing and burning oxide or chalcogenide and silicon dioxide, as a negative electrode material in a nonaqueous electrolyte secondary battery. CONSTITUTION: A nonaqueous secondary battery consists of a positive electrode active material, a negative electrode material, a separator, and a nonaqueous electrolyte containing lithium salt. A compound prepared by burning a mixture of composition MZ.pGO is desirable for the negative electrode material. MZ represents at least one kind of oxide of a substance selected from Sn, Ge, Pb, Sb, Bi, while GO represents an amorphous networking structure forming agent containing at least silicon dioxide. The compound prepared by burning contains a non-stoichiometric compound in which a ratio of oxygen is not stoichiometric, a compound with plural number of valence, and a heterogeneous compound. On the other hand, (p) representing a molar ratio between a lithium adsorption/ desorption site and a dispersion medium is set to be 0.33-2 desirably.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel non-aqueous secondary battery having a high discharge potential, a high capacity, good cycleability, good storage stability and excellent safety.

[0002]

2. Description of the Related Art In recent years, with the widespread use of portable personal computers and mobile phones, there has been an increasing demand for higher capacity secondary batteries. Therefore, a lithium secondary battery capable of high capacity has been extensively developed.

From the beginning of the development of lithium secondary batteries, lithium metal and lithium alloys, which have a high capacity, have been typical as a negative electrode material, but there is a risk of ignition or explosion due to dendrite formation. Therefore, a calcined carbonaceous material capable of inserting and releasing lithium has come into practical use. However, the carbonaceous material has a defect that the discharge capacity is small.

Further, SnO is disclosed in JP-A-6-275268, and silicon oxide is disclosed in JP-A-6-325765, particularly silicon oxide in which silicon has a valence of 4 or less, JP-A-6-338325. The publication describes that a composite oxide of tin and another element is used as a negative electrode material. Some of these negative electrode materials have high discharge potential and high capacity, but their cycleability was insufficient. Further, due to its high capacity, accidents such as a sudden rise in battery temperature due to an abnormality such as a short circuit and a squirt of battery contents are likely to occur, so that safety is not sufficiently ensured.

[0005]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a non-aqueous secondary battery having high discharge potential, high capacity, good cycleability and excellent safety.

[0006]

Means for Solving the Problems The above-mentioned problem is a non-aqueous secondary battery comprising a positive electrode active material, a negative electrode material, a separator and a non-aqueous electrolyte containing a lithium salt, wherein the negative electrode material is
This can be achieved by a non-aqueous electrolyte secondary battery characterized by being an amorphous compound obtained by mixing and firing an oxide or chalcogenide and silicon dioxide.

The present invention will be described in detail below. The negative electrode material of the present invention is an amorphous oxide or chalcogenide, and is preferably mainly amorphous when incorporated in a battery. The term "amorphous" as used herein means a substance having a broad scattering band having an apex at a 20 value of 20 ° to 40 ° by an X-ray diffraction method using CuKα rays, and has a crystalline diffraction line. Good. Preferably 2θ value is 40 ° or more and 70 °
The strongest of the crystalline diffraction lines seen below is 2
It is preferably 500 times or less, more preferably 100 times or less, particularly preferably 5 times or less, of the diffraction line intensity at the apex of the broad scattering band seen in the θ value of 20 ° or more and 40 ° or less. Most preferably, it has no crystalline diffraction line.

A more preferable negative electrode material is silicon dioxide,
It is an amorphous composite oxide obtained by mixing and firing at least one oxide of an element selected from Sn, Ge, Pb, Sb and Bi, and is obtained by firing a mixture of the following composition MZ · pGO. Is a compound. Here, MZ is Sn, G
An element selected from e, Pb, Sb and Bi represents at least one kind of oxide, and GO represents an amorphous network forming agent containing at least silicon dioxide. The compound obtained by firing,
A non-stoichiometric compound having a non-stoichiometric ratio with oxygen, a compound having a plurality of valences, a disproportionated compound and the like are also included. p represents the molar ratio of the lithium adsorption / desorption site to the dispersion medium, and is 0.2
It is 5 to 5, more preferably 0.33 to 2.

[0009] MZ is an inorganic oxide involved in the absorption and desorption of lithium ions, and it is considered that during the charge and discharge reaction of the battery, MZ coordinates lithium and simultaneously coordinates lithium to provide a site for lithium adsorption and desorption. In order to stabilize the charge / discharge cycle, it is necessary that the lithium adsorption / desorption sites are stably dispersed in the medium, and the amorphous network former GO serves as a dispersion medium for the adsorption / desorption sites. It is believed that. Examples of MZ include GeO, GeO ₂ , S
nO, SnO ₂ , PbO, PbO ₂ , Pb ₂ O ₃ , Pb
₂ O ₄ , Pb ₃ O ₄ , Sb ₂ O ₃ , Sb ₂ O ₄ , Sb ₂
O ₅ , Bi ₂ O ₃ , Bi ₂ O ₄ , Bi ₂ O ₅ and the like are preferable. Further, these may be composite oxides with lithium oxide, such as Li ₂ GeO ₃ and Li ₂ SnO ₂ .
Of these, SnO, SnO ₂ , and GeO are more preferable.
These can be used alone or in combination.

The amorphous network forming agent GO may be any one that forms an amorphous network with MZ, and examples thereof include compounds of B, P and Al in addition to silicon compounds. Of these, those that form an amorphous network structure after being baked together with MZ described above are preferred.

The negative electrode material of the present invention has a composition, MZ · pGO.
The following compounds can be used as MZ and GO. These compounds may include a plurality of each. As the Si compound, for example, S
iO ₂ , halogenated organosilicon compounds such as silicon tetrachloride, silicon tetrabromide, trichloromethylsilane, dimethyldichlorosilane and trimethylchlorosilane, organosilicon compounds such as tetramethylsilane and tetraethylsilane, tetramethoxysilane, tetraethoxysilane and the like. And alkoxysilane compounds, and hydrosilane compounds such as trichlorohydrosilane.

Examples of the Sn compound include Sn O and Sn
O₂, Sn₂O₃, Sn₃O_Four, Sn₇O ₁₃・ H₂O, Sn₈O
_Fifteen, Stannous hydroxide, stannic oxyhydroxide, stannic acid, oxalic acid
Stannous, stannous phosphate, orthostannic acid, metastannic acid, paratin
Acid, stannous fluoride, stannic fluoride, stannous chloride, stannic chloride
Tin, stannous bromide, stannic bromide, stannous iodide, stannic iodide
Tin, tin selenide, tin telluride, stannous pyrophosphate, phosphorus
Examples include tin oxide, stannous sulfide, stannic sulfide, and the like.
It

Examples of the Ge compound include GeO ₂ and G
Examples include alkoxy germanium compounds such as eO, germanium tetrachloride, germanium tetrabromide, germanium tetramethoxide, and germanium tetraethoxide. Examples of the Pb compound include PbO ₂ and Pb
O, Pb ₂ O ₃ , Pb ₃ O ₄ , PbCl ₂ , lead chlorate,
Examples thereof include lead perchlorate, lead nitrate, lead carbonate, lead formate, lead acetate, lead tetraacetate, lead tartrate, lead diethoxide, and lead di (isopropoxide).

Examples of the P compound include phosphorus pentaoxide, phosphorus oxychloride, phosphorus pentachloride, phosphorus trichloride, phosphorus tribromide,
Examples thereof include trimethyl phosphoric acid, triethyl phosphoric acid, tripropyl phosphoric acid, stannous pyrophosphate, and boron phosphate. Examples of the B compound include boron trioxide,
Examples thereof include boron trichloride, boron tribromide, boron carbide, boric acid, trimethyl borate, triethyl borate, tripropyl borate, tributyl borate, boron phosphide and boron phosphate. Examples of the Al compound include aluminum oxide (α-alumina, β-alumina), aluminum silicate, aluminum tri-iso-propoxide, aluminum tellurite, aluminum chloride, aluminum boride, aluminum phosphide, aluminum phosphate, lactic acid. Examples thereof include aluminum, aluminum borate, aluminum sulfide, aluminum sulfate, aluminum boride and the like.

Particularly preferred compounds among the above compounds
Has the composition SnO.qSiO₂-Firing a mixture of rGO '
It is a compound obtained by Where GO 'is the above-mentioned amorphous
Compounds obtained by removing tin compounds and silicon compounds from the organic network forming agents
Represents a thing. GO 'may be a single compound or a plurality of compounds.
It may be a thing. q and r are 0.1 to 2.0 respectively
R / q = 0.05 to 10, more preferably 0.2 to
1.2 and r / q = 0.1-5. Compound of the present invention
The following can be cited as examples of
It is not limited to these. SnB_0.5P_0.5O₃, SnAl_0.3B_0.5P_0.2O
_2.7, SnAl_0.3B_{0. 7}O_2.5, SnSi_0.8P_0.2
O_3.1, SnSi_0.8B_0.2O_2.9, SnSi_{0. 8}Al
_0.2O_2.9, SnSi_0.6Al_0.2B_0.2O_2.8, Sn
Si_0.6Al_0.2P_0.2O₃, SnSi_0.6B_0.2P
_0.2O₃, SnSi_0.4Al_0.2B_0.4O_{2. 7}, SnS
i_0.6Al_0.1B_0.1P_0.3O_3.25, SnSi_0.6Al
_0.1B_0.3P _0.1O_3.05, SnSi_0.5Al_0.3B_0.4
P_0.2O_3.55, SnSi_0.5Al_0.3B_0.4P_0.5O
_4.30, SnSi_0.8Al_0.3B_0.2P_0.2O_3.85

In the present invention, the compound as shown above is used.
By using the material as the negative electrode material,
Excellent discharge cycle characteristics, high discharge voltage and high capacity
A non-aqueous secondary battery with high safety and excellent quick charging characteristics
Obtainable. In the present invention, particularly excellent effects
What can be obtained is that it contains Sn and the valence of Sn is
By using a compound that exists in two valences as a negative electrode material,
It The valence of Sn can be obtained by chemical titration operation.
Wear. For example, Physics and Chemistry of Glasses Vol.8
 It can be analyzed by the method described on page 165 of No. 4 (1967).
it can. For solid-state nuclear magnetic resonance (NMR) measurement of Sn
It is also possible to determine from the night shift according to. example
For example, in wide measurement, metallic Sn (zero-valent Sn) is Sn.
(CH₃) _FourExtremely low magnetic field around 7,000 ppm
While a peak appears in the field, in SnO (= bivalent)
Near 100ppm, SnO₂(= 4 valence) -600p
Appears near pm. In this way, if they have the same ligand,
The total night shift depends largely on the valence of Sn, which is the central metal.
Since it exists, the peak determined by 119 Sn-NMR measurement
It is possible to determine the valence at the position.

Various compounds can be included in the negative electrode material of the present invention. For example, Group 1 elements (Li, Na, K, R
b, Cs), Group 2 element (Be, Mg, Ca, Sr, B
a), transition metals (Sc, Ti, V, Cr, Mn, Fe,
Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, T
c, Ru, Rh, Pd, Ag, Cd, lanthanoid metal, Hf, Ta, W, Re, Os, Ir, Pt, Au,
Hg) or a periodic table group 17 element (F, Cl, Br, I) can be included. It may also contain a dopant of various compounds (for example, compounds of Sb, In, and Nb) that enhance electron conductivity. The amount of compound added is 0 to 20 mol%
Is preferred. The calcination method is preferable as the method for synthesizing the complex chalcogen compound and the complex oxide in the present invention. The firing method will be described in detail. Si, Ge, Sn, Pb, P, B,
A predetermined amount of three or more compounds of Al, As, and Sb may be mixed, and the mixture may be fired under the firing conditions described below. The compounds of the present invention also include non-stoichiometric compounds produced during firing and elements having different valences produced by the disproportionation reaction.

The firing conditions are preferably a heating rate of 4 ° C./min to 2000 ° C./min.
More preferably, it is 6 ° C. or higher and 2000 ° C. or lower. Particularly preferably, it is 10 ° C or higher and 2000 ° C or lower, and the firing temperature is preferably 250 ° C or higher and 1500 ° C or lower, and more preferably 350 ° C or higher and 1500 ° C.
Or less, particularly preferably 500 ° C or higher and 1500 ° C
And the firing time is 0.01 hours or more 1
It is preferably 00 hours or less, more preferably 0.5 hours or more and 70 hours or less, particularly preferably 1 hour or more and 20 hours or less, and the temperature decreasing rate is 2 ° C or more and 10 ⁷ ° C or less per minute. It is preferably 4 ° C or more and 10 ⁷ ° C or less, particularly preferably 6 ° C or more and 10 ⁷ ° C or less, and particularly preferably 1
It is 0 ° C. or higher and 10 ⁷ ° C. or lower. The rate of temperature rise in the present invention is the average rate of temperature increase from "50% of the firing temperature (indicated in ° C)" to "80% of the firing temperature (indicated in ° C)", and the rate of temperature decrease in the present invention is "Baking temperature (℃
80% of "displayed" to "50% of firing temperature (displayed in ° C)"
Is the average rate of temperature drop until reaching. The temperature may be lowered in the firing furnace or may be taken out of the firing furnace and put in water for cooling. Also, ceramic processing (Gihodo Shuppan 1987), page 217, gun method, Hammer-Anvil method, slap method,
Gas atomization method, plasma spray method, centrifugal quenching method,
An ultraquenching method such as the melt drag method can also be used. See also New Glass Handbook (Maruzen 199
1) Cooling may be performed using the single roller method or the twin roller method described on page 172. In the case of a material that melts during firing, the fired product may be continuously taken out while supplying the raw material during firing. In the case of a material that melts during firing, it is preferable to stir the melt.

The firing gas atmosphere is preferably an atmosphere having an oxygen content of 5% by volume or less, and more preferably an inert gas atmosphere. Examples of the inert gas include nitrogen, argon, helium, krypton, xenon and the like. The average particle size of the compounds represented by the general formulas (1) to (3) used in the present invention is preferably 0.1 to 60 μm,
1.0 to 30 μm is particularly preferable, and 2.0 to 20 μm is more preferable. A well-known crusher or classifier is used to obtain a predetermined particle size. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a satellite ball mill, a planetary ball mill, a swirling airflow type jet mill, a sieve and the like are used. At the time of pulverization, wet pulverization in which water or an organic solvent such as methanol is allowed to coexist can be performed as necessary. In order to obtain the desired particle size, it is preferable to carry out classification. The classification method is not particularly limited, and a sieve, an air classifier, or the like can be used as necessary. Classification can be carried out both dry and wet.

As shown in the examples, by using the negative electrode material of the present invention containing silicon dioxide and having an amorphous network structure, a battery having a high capacity and good cycleability can be manufactured. However, with these high-capacity batteries, an abnormal current may flow due to an external short circuit or the like caused by misuse such as forced discharge, which may cause an accident such as a remarkable increase in internal temperature, ejection of contents, or rupture of battery can. is there. In order to prevent these, measures such as a safety valve and a current cut-off element such as a PTC have been incorporated, but this is not an essential solution to heat generation. In the present invention, in order to improve safety, it is preferable to use the above negative electrode material in combination with the separator described below.

As the separator, a material having a large ion permeability, a predetermined mechanical strength, and insulating micropores or gaps is used. Further, in order to improve safety, it is necessary to have a function of blocking the current by closing the above-mentioned gap at 80 ° C. or more to increase resistance. The closing temperature of these gaps is 90 ° C. or higher and 180 ° C. or lower, and more preferably 110 ° C. or higher and 170 ° C. or lower. The method of forming the gap depends on the material, but any known method may be used. In the case of a porous film, the shape of the holes is usually circular or elliptical, and the size thereof is 0.05 μm to 30 μm, preferably 0.1 μm to 20 μm. Further, as in the case of the stretching method or the phase separation method, the holes may be rod-shaped or amorphous. In the case of cloth, the gap is a space between fibers and depends on how to make a woven or non-woven fabric. The ratio of these gaps, that is, the porosity is 20% to 90%,
35% to 80% is preferable.

The separator of the present invention has a thickness of 5 μm or more and 10
A microporous film having a thickness of 0 μm or less, more preferably 10 μm or more and 80 μm or less, a woven fabric, a non-woven fabric, or the like.
The separator of the present invention contains at least 2 ethylene components.
Polymers containing 0% by weight are preferred, with 3 being especially preferred.
It contains 0% or more. As components other than ethylene, propylene, butene, hexene, fluorinated ethylene,
Examples thereof include vinyl chloride, vinyl acetate and acetalized vinyl alcohol, with propylene and fluorinated ethylene being particularly preferred. The microporous film is preferably made of polyethylene, an ethylene-propylene copolymer or an ethylene-butene copolymer. Further, those made by mixing and dissolving polyethylene and polypropylene and polyethylene and polytetrafluoroethylene are also preferable. The non-woven fabric or woven fabric has a thread diameter of 0.1 μm to 5 μm, and is made of polyethylene, ethylene-propylene copolymer, ethylene-butene 1 copolymer, ethylene-methylbutene copolymer, ethylene-methylpentene copolymer, polypropylene, A yarn made of polytetrafluoroethylene fiber yarn is preferable. These separators may be a single material or a composite material. In particular, a laminate of two or more kinds of microporous films having different pore diameters, porosities, pore blocking temperatures, etc., a microporous film and a non-woven fabric,
A composite of microporous film and woven fabric, and non-woven fabric and paper in different forms are particularly preferable. The separator of the present invention may contain inorganic fibers such as glass fibers and carbon fibers, and particles of inorganic substances such as silicon dioxide, zeolite, alumina and talc. Further, the voids and the surface may be treated with a surfactant to make them hydrophilic.

The positive and negative electrodes used in the non-aqueous secondary battery of the present invention can be prepared by coating a positive electrode mixture or a negative electrode mixture on a current collector. The positive electrode or the negative electrode mixture can contain a positive electrode active material or a negative electrode material, as well as a conductive agent, a binder, a dispersant, a filler, an ion conductive agent, a pressure enhancer or various additives, respectively. The positive electrode active material used in the present invention may be a compound capable of inserting and extracting light metal ions, and is particularly selected from transition metal oxides and transition metal chalcogenides. A transition metal oxide is particularly preferable, and a transition metal oxide containing lithium is particularly preferable.

Preferred transition metals used in the present invention include Ti, V, Cr, Mn, Fe, Co, Ni, Cu,
Nb, Mo and W can be mentioned. Among these transition metal compounds, manganese dioxide, vanadium pentoxide,
Iron oxide, molybdenum oxide, molybdenum sulfide, cobalt oxide, iron sulfide, titanium sulfide and the like are preferable. These compounds can be used alone or in combination of two or more kinds. It can also be used as a transition metal oxide containing lithium.

In addition to lithium compounds and transition metal compounds,
In general, compounds that enhance ionic conductivity, such as Ca ²⁺ ,
Alternatively, an amorphous network forming agent containing P, B or Si (for example, P ₂ O ₅ , Li ₃ PO ₄ , H ₃ BO ₃ , B ₂
O _3, etc. SiO ₂₎ and may be fired by mixing. In addition, alkali metal ions such as Na, K and Mg and /
Or Si, Sn, Al, Ga, Ge, Ce, In, B
You may mix with a compound containing i etc., and may bake. The transition metal oxide containing lithium is, for example, a lithium compound,
It can be synthesized by firing a mixture of transition metal compounds. Specific examples of preferable positive electrode active materials used in the present invention include JP-A-61-2562, US Pat. No. 4,302,518, and JP-A-63-29905.
6, JP-A-1-294364, JP-B-4-3014
6, U.S. Pat. Nos. 5,240,794 and 5,15.
3,081, JP-A-4-328,258, JP-A-5
-54, 889 and the like. Representative compounds are shown below, but the present invention is not limited thereto.

Li _x CoO ₂ , Li _x NiO ₂ , Li _x
Co _a Ni _1-a O ₂ , Li _x Co _b V _1-b O _z , Li _x
Co _b Fe _1-b O _z , Li _x Mn ₂ O ₄ , Li _x Mn
O ₂ , Li _x Mn ₂ O ₃ , Li _x Mn _b Co _2-b O _z ,
_{Li x Mn b Ni 2-b} O z, Li x Mn b V 2-b O z,
Li _x Mn _b Fe _1-b O _z , Li _x Co _c B _1-c O
₂ (where x = 0.05 to 1.2, a = 0.1 to 0.
9, b = 0.8 to 0.98, c = 0.85 to 0.99,
z = 1.5 to 5).

The positive electrode active material used in the present invention can be synthesized by a method of mixing and firing a lithium compound and a transition metal compound or a solution reaction, but a firing method is particularly preferable. Details for firing are described in paragraphs 0035 of JP-A-6-60,867, JP-A-7-14,579 and the like, and these methods can be used. The positive electrode active material obtained by firing may be used after being washed with water, an acidic aqueous solution, an alkaline aqueous solution, or an organic solvent. Furthermore,
The method of chemically inserting lithium ions into the transition metal oxide may be a method of synthesizing lithium metal, a lithium alloy, or butyl lithium by reacting with the transition metal oxide.

The average particle size of the positive electrode active material used in the present invention is preferably 0.1 to 50 μm. 0.5-30 μm
It is preferable that the volume of the particles is 95% or more. The specific surface area is not particularly limited, but is 0.01 by the BET method.
˜50 m ² / g is preferred. The pH of the supernatant liquid when 5 g of the positive electrode active material was dissolved in 100 ml of distilled water was 7
It is preferably 12 or more and 12 or less. In addition to this, the surfaces of the positive electrode active material and the negative electrode material can be modified. For example,
The surface of the metal oxide may be treated with an esterifying agent, a chelating agent, a conductive polymer or polyethylene oxide. Also, the surface of the negative electrode material can be modified. For example, the treatment may be performed by providing an ion conductive polymer or a polyacetylene layer. Further, the positive electrode active material and the negative electrode material may be subjected to a purification step such as washing with water.

As the electrode mixture, a conductive agent, a binder, a filler, a dispersant, an ionic conductive agent, a pressure enhancer and various other additives can be used. The conductive agent may be any electron-conductive material that does not cause a chemical change in the constructed battery. Usually, natural graphite (scaly graphite, flake graphite, earthy graphite, etc.), graphite such as artificial graphite, acetylene black, Ketjen black, channel black, furnace black, lamp black,
Carbon blacks such as thermal black, conductive fibers such as carbon fibers and metal fibers, metal powders such as copper, nickel, aluminum and silver, conductive whiskers such as zinc oxide and potassium titanate, oxidation A conductive metal oxide such as titanium or an organic conductive material such as a polyphenylene derivative can be contained alone or as a mixture thereof. Among these conductive agents, acetylene black, and the combined use of graphite and acetylene black are particularly preferable. The amount added is not particularly limited, but is 1
-50% by weight is preferable, and 1-30% by weight is particularly preferable. For carbon and graphite, 2 to 15% by weight is particularly preferable.

As the binder, one or a mixture of polysaccharides, thermoplastic resins and polymers having rubber elasticity can be used. Preferred examples are starch, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose,
Diacetyl cellulose, polyvinyl chloride, polyvinylpyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, polybutadiene, fluororubber and polyethylene oxide. Can be mentioned. When a compound containing a functional group that reacts with lithium, such as a polysaccharide, is used, it is preferable to add a compound such as an isocyanate group to deactivate the functional group. The amount of the binder added is not particularly limited, but is preferably 1 to 50% by weight, and particularly 2
-30% by weight is preferred. The distribution of the binder in the mixture may be uniform or non-uniform.

As the filler, any fibrous material which does not cause a chemical change in the constructed battery can be used. Generally, olefin polymers such as polypropylene and polyethylene, fibers such as glass and carbon are used. The amount of the filler added is not particularly limited, but is 0
-30% by weight is preferred. As the ionic conductive agent, those known as inorganic and organic solid electrolytes can be used, and details are described in the section of the electrolytic solution. The pressure enhancer is a compound that increases the internal pressure described later, and a typical example is carbonate.

The electrolyte is generally dissolved in the solvent and the solvent.
Lithium salt (anion and lithium cation) to be solved
It is composed of As the solvent, propylene carbonate
, Ethylene carbonate, butylene carbonate,
Dimethyl carbonate, diethyl carbonate, methyl
Ethyl carbonate, γ-butyrolactone, methyl formate
, Methyl acetate, 1,2-dimethoxyethane, tetrahi
Drofuran, 2-methyltetrahydrofuran, dimethyl
Sulfoxide, 1,3-dioxolane, formamide,
Dimethylformamide, dioxolane, acetonitril
, Nitromethane, ethyl monoglyme, triphosphate
Stell, trimethoxymethane, dioxolane derivative, suture
Luforane, 3-methyl-2-oxazolidinone, propyi
Len carbonate derivative, tetrahydrofuran derivative,
Non-preservatives such as ethyl ether and 1,3-propane sultone
Examples include rotonic organic solvents, one of these
Or, two or more kinds are mixed and used. Soluble in these solvents
As the cation of the lithium salt to be used, for example, ClO_Four
^-, BF_Four ^-, PF₆ ^-, CF₃SO₃ ^-, CF₃CO
₂ ^-, AsF₆ ^-, SbF₆ ^-, (CF₃SO₂)₂N
^-, B_TenCl_Ten ^2-, (1,2-dimethoxyethane)₂C
10_Four ^-, Lower aliphatic carboxylate ion, AlC
l_Four ^-, Cl^-, Br^-, I^-Of chloroborane compounds
Anion, tetraphenyl borate ion can be mentioned
You can use one or more of these
It Above all, cyclic carbonate and / or acyclic car
It is preferable to include a bonate. For example, diethyl
Carbonate, dimethyl carbonate, methyl ethyl carbonate
It is preferable to include a carbonate. Also, ethylene
Carbonate, propylene carbonate
Is preferred. In addition to ethylene carbonate,
Pyrene carbonate, 1,2-dimethoxyethane, dime
Cyl carbonate or diethyl carbonate as appropriate
LiCF in the mixed electrolyte₃SO₃, LiClO_Four, L
iBF_FourAnd / or LiPF₆Electrolyte containing
Good. In those supporting salts, LiPF₆Include
And are particularly preferred.

The amount of these electrolytes to be added into the battery is not particularly limited, but it can be used in the required amount depending on the amount of the positive electrode active material or the negative electrode material and the size of the battery. The concentration of the supporting electrolyte is not particularly limited, but is preferably 0.2 to 3 mol per liter of the electrolytic solution.

In addition to the electrolytic solution, the following solid electrolytes can be used together. Solid electrolytes are classified into inorganic solid electrolytes and organic solid electrolytes. Li-nitrides, halides, oxyacid salts, and the like are well known as inorganic solid electrolytes. Among them, Li ₃ N, LiI, Li _{5
NI 2, Li 3 N-LiI} -LiOH, Li 4 Si
O ₄ , Li ₄ SiO ₄ -LiI-LiOH, x Li ₃ P
_{O 4 - (1-x)} Li 4 SiO 4, Li 2 SiS 3, it is effective and phosphorus sulfide compounds.

In the organic solid electrolyte, a polyethylene oxide derivative or a polymer containing the derivative, a polypropylene oxide derivative or a polymer containing the derivative, a polymer containing an ionic dissociative group, a mixture of the polymer containing an ionic dissociative group and the above aprotic electrolyte solution. A polymer matrix material containing a phosphoric acid ester polymer and an aprotic polar solvent is effective. Furthermore, there is also a method of adding polyacrylonitrile to the electrolytic solution. Also known is a method of using an inorganic and organic solid electrolyte in combination.

Further, other compounds may be added to the electrolyte for the purpose of improving discharge and charge / discharge characteristics. For example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivative,
Sulfur, quinone imine dye, N-substituted oxazolidinone and N, N'-substituted imidazolidinone, ethylene glycol dialkyl ether, quaternary ammonium salt, polyethylene glycol, pyrrole, 2-methoxyethanol, A
lCl ₃ , a conductive polymer electrode active material monomer, triethylenephosphoramide, trialkylphosphine, morpholine, an aryl compound having a carbonyl group, 12-
Crown ethers such as Crown-4, hexamethylphosphoric triamide and 4-alkylmorpholine,
Examples include bicyclic tertiary amines, oils, quaternary phosphonium salts, and tertiary sulfonium salts.

Further, in order to make the electrolytic solution nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolytic solution. Further, the electrolytic solution may contain carbon dioxide gas in order to have suitability for high temperature storage. Further, the mixture of the positive electrode and the negative electrode can contain an electrolytic solution or an electrolyte. For example, a method is known in which the ion conductive polymer, nitromethane, and an electrolytic solution are contained.

The collector of the electrode active material may be any electron conductor as long as it does not cause a chemical change in the constructed battery. For example, for the positive electrode, in addition to stainless steel, nickel, aluminum, titanium, carbon, or the like, a material obtained by treating the surface of aluminum or stainless steel with carbon, nickel, titanium, or silver is used. Particularly, aluminum or aluminum alloy is preferable. For the negative electrode, in addition to stainless steel, nickel, copper, titanium, aluminum, carbon, etc. as a material, a material obtained by treating the surface of copper or stainless steel with carbon, nickel, titanium or silver, or an Al-Cd alloy is used. To be Particularly, copper or copper alloy is preferable. It is also used to oxidize the surface of these materials. Further, it is desirable to make the surface of the current collector uneven by surface treatment. As the shape, in addition to the foil, a film, a sheet, a net, a punched product, 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
Those having a thickness of up to 500 μm are used.

The shape of the battery can be any of coins, buttons, sheets, cylinders, flats, corners and the like. When the shape of the battery is a coin or a button, the mixture of the positive electrode active material and the negative electrode material is mainly used after being compressed into a pellet shape.
The thickness and diameter of the pellet are determined by the size of the battery. When the shape of the battery is a sheet, a cylinder, or a corner, the mixture of the positive electrode active material and the negative electrode material is mainly used after being applied (coated), dried, and compressed on the current collector. As a coating method, a general method can be used. For example,
Reverse roll method, direct roll method, blade method,
Knife method, extrusion method, curtain method, gravure method, bar method, dip method and squeeze method can be mentioned. Among them, the blade method, the knife method and the extrusion method are preferable. Application is 0.1-10
It is preferably carried out at a speed of 0 m / min. On this occasion,
By selecting the above coating method according to the solution physical properties and drying properties of the mixture, a good surface state of the coating layer can be obtained. The coating may be performed one by one or simultaneously on both sides. The coating may be continuous, intermittent or striped. The thickness, length and width of the coating layer are determined by the size of the battery, but the thickness of the coating layer on one side is particularly preferably 1 to 2000 μm in the compressed state after drying.

As a method for drying or dehydrating the pellets or sheets, a generally adopted method can be used. In particular, it is preferable to use hot air, vacuum, infrared rays, far infrared rays, electron beams, and low humidity air alone or in combination. The temperature is preferably in the range of 80 to 350 ° C, particularly 10
The range of 0 to 250 ° C. is preferable. The water content of the whole battery is preferably 2000 ppm or less, and the content of each of the positive electrode mixture, the negative electrode mixture and the electrolyte is preferably 500 ppm or less from the viewpoint of cycleability. As a pellet or sheet pressing method, a generally adopted method can be used, but a die pressing method or a calendar pressing method is particularly preferable. The pressing pressure is not particularly limited, but is 0.2 to 3 t /
cm ² is preferred. The press speed of the calendar press method is preferably 0.1 to 50 m / min. The pressing temperature is preferably room temperature to 200 ° C. The width ratio of the negative electrode sheet to the positive electrode sheet is preferably 0.9 to 1.1. In particular,
0.95-1.0 is preferable. Since the content ratio of the positive electrode active material and the negative electrode material differs depending on the compound type and mixture formulation,
Although not limited, it can be set to an optimum value in terms of capacity, cycleability, and safety.

Stacked with the mixture sheet via a separator
After being fitted, the sheets can be rolled or folded.
Insert it into the can, connect the can and the sheet electrically, and
Inject and use the sealing plate to form a battery can. At this time,
The safety valve can be used as a sealing plate. Safety valve
In addition, equipped with various conventionally known safety elements
Is also good. For example, fuses,
Immetal, PTC element, etc. are used. Also, the safety valve
In addition to the above, cut into the battery can as a measure to increase the internal pressure of the battery can
Inserting method, gasket cracking method or sealing plate cracking
Method or cutting method with lead plate can be used.
Wear. In addition, the charger has built-in measures against overcharge and overdischarge.
Either have a protection circuit or connect it independently
Good. Also, as a measure against overcharge, increase the internal pressure of the battery.
It is possible to provide a method of cutting off the electric current. This and
A compound that raises the internal pressure in the mixture or in the electrolyte.
Can be included in. As a compound that increases internal pressure
Is Li₂CO₃, LiHCO ₃, Na₂CO₃, Na
HCO₃, CaCO₃, MgCO₃Such as carbonate
can give. Cans and lead plates are made of metal or
Alloys can be used. For example, iron, nickel, chi
Gold such as tan, chrome, molybdenum, copper, aluminum
A genus or an alloy thereof is used. Caps, cans,
Welding methods for sheets and lead plates are known methods (eg, direct current or
Is AC electric welding, laser welding, ultrasonic welding)
Can be Sealing agents for sealing are asphalt, etc.
It is possible to use conventionally known compounds and mixtures of
it can.

The application of the non-aqueous secondary battery of the present invention is not particularly limited. For example, when it is mounted on an electronic device, a color notebook computer, a black and white notebook computer, a sub notebook computer, a pen input computer, a pocket (palmtop). PC, notebook word processor, pocket word processor, e-book player, mobile phone, cordless phone handset, pager, handy terminal, mobile fax, mobile copy, mobile printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD, Mini disks, electric shavers, electronic translators, car phones, transceivers, power tools, electronic organizers, calculators, memory cards, tape recorders, radios, backup power supplies, memory cards, etc. Other consumer products include automobiles, electric vehicles, motors, lighting equipment, toys, game machines, road conditioners, irons, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.) and the like. Furthermore, it can be used for various military purposes and for space. It can also be combined with other secondary batteries, solar cells, or primary batteries.

[0043]

EXAMPLES The present invention will be described in more detail with reference to specific examples below, but the present invention is not limited to the examples as long as the gist of the invention is not exceeded.

Synthesis Example-1 Predetermined amounts of tin monoxide, silicon dioxide, aluminum oxide, and
Dry mix of diboron oxide and phosphorus pentoxide, made of alumina
Place it in a bowl and heat it to 1000 ° C at 15 ° C / min in an argon atmosphere.
The temperature was raised. After firing at 1150 ° C for 12 hours, 10 ° C
/ Min to room temperature, remove from the firing furnace,
Coarsely crushed and then crushed with a jet mill for composition analysis
SnSi with an average particle size of 5.5 μm_0.8Al_0.2B_0.4
P_0.2O _FourWas obtained (Compound A). This compound is CuK
In the X-ray diffraction method using α rays, the 2θ value was around 27 °.
It has a peak with a broad peak and has 2θ
A crystalline diffraction line is observed at a value of 40 ° to 70 °
However, it was confirmed to be an amorphous substance. Similar to compound A
And SnSi_0.5B_0.3P_0.1Mg_0.1O_2.6(Compound
Material B), SnSiO₃(Compound C) and prepared in the same manner
It was confirmed to be amorphous. As a compound for comparison
Then, a predetermined amount of silicon monoxide and tin monoxide are mixed and fired,
Sn_0.67Si_0.33O (compound d), and further commercial monoxide
Tin was used as a comparative compound e. All of these are crystalline
Was a compound of.

The following were prepared as separators. S-1: Polyethylene film having a thickness of 50 μm and a porosity of 63%. S-2: An ethylene-propylene copolymer film having a thickness of 50 μm and a porosity of 62% (ethylene 50% by weight). S-3: A composite film obtained by laminating a polyethylene film having a thickness of 25 μm and a porosity of 66% with a polypropylene film having a thickness of 25 μm and a porosity of 62%. S-4: Polyethylene yarn having an average fiber diameter of 1 μm and polypropylene yarn having the same weight and an average fiber diameter of 1 μm, having a thickness of 5
0 μm non-woven fabric S-5; polyethylene fiber having an average fiber diameter of 1 μm 30% by weight
And a non-woven fabric having a thickness of 50 μm and made of 70% by weight of polypropylene yarn having an average fiber diameter of 1 μm S-6; S-2 except that ethylene is 20% by weight.
Same as. S-7; 20% by weight of polyethylene yarn having an average fiber diameter of 1 μm
Then, a non-woven fabric having a thickness of 50 μm and made of 80% by weight of polypropylene yarn having an average fiber diameter of 1 μm was prepared as a separator other than the present invention. SC1; 10% by weight of polyethylene yarn having an average fiber diameter of 1 μm
And a nonwoven fabric SC2 having a thickness of 50 μm and made of 90% by weight of polypropylene yarn having an average fiber diameter of 1 μm SC2; a polypropylene film having a thickness of 50 μm and a porosity of 62%. SC3; S-2 except that ethylene is 10% by weight
Same as.

Example 1 As a negative electrode material, 86 wt% of compound 1-A, 6 wt% of scaly graphite and 3 wt% of acetylene black were mixed, and an aqueous dispersion of polyvinylidene fluoride was used as a binder. 4% by weight and carboxymethylcellulose 1% by weight
Was added and kneaded with water as a medium to prepare a slurry.
The slurry was applied on both sides of a copper foil having a thickness of 18 μm by an extrusion method, dried, compression-molded by a calender press, and cut into a predetermined width and length to prepare a strip-shaped negative electrode sheet. The thickness of the negative electrode sheet was 124 μm. As a positive electrode material, 87% by weight of LiCoO ₂ , 6% by weight of flake graphite, 3% by weight of acetylene black, and 3% by weight of polytetrafluoroethylene aqueous dispersion 3 as a binder.
% By weight and 1% by weight of sodium polyacrylate and kneaded with water as a medium to obtain a slurry having a thickness of 20 μm.
The aluminum foil was coated on both sides by the same method as above, dried, press-compressed, and cut to prepare a strip-shaped positive electrode sheet. The thickness of the positive electrode sheet was 280 μm. After spot welding nickel and aluminum lead plates to the respective ends of the negative electrode sheet and the positive electrode sheet, dehydration drying was performed for 2 hours at 150 ° C. in dry air having a dew point of −40 ° C. or less.

Next, a dehydrated and dried positive electrode sheet (5), a separator (3), a dehydrated and dried negative electrode sheet (4), and a separator were laminated in this order, wound spirally, and the outermost periphery was taped to a wound body. It was created. This wound body was housed in a stainless steel bottomed cylindrical battery can (2) plated with nickel which also serves as a negative electrode terminal. LiPF per liter
_An electrolyte containing 0.9 and 0.1 mol of ₆ and LiBF ₄ , respectively, and a solvent of ethylene carbonate and a 2: 2: 6 volume mixture of butylene carbonate and dimethyl carbonate was injected into a battery can. Immediately after the injection, the battery lid (8) having the positive electrode terminal was caulked and sealed via the gasket (1) to produce cylindrical batteries D-1 to D-3. The positive electrode terminal (8) was connected to the positive electrode sheet (5), and the battery can (2) was connected to the negative electrode sheet (4) by a lead terminal in advance. FIG. 2 shows a cross section of the cylindrical battery. Incidentally, (7) is a safety valve, which is set to open when the pressure inside the battery can exceeds 15 kgf / cm ² . Compounds A to e were used as the negative electrode materials and S-1 to S-5 were used as the separators to produce the batteries shown in the table below. Charge / discharge test conditions are 4.3-
The voltage was 2.7 V and 1 mA / cm ² . Further, the battery charged to 4.5 V was externally short-circuited, and the condition at the time of short-circuit was examined. The results are shown in the table below.

Description of abbreviations: battery number, negative electrode material, separator, fifth discharge capacity (mAh per 1 g of negative electrode material), charge / discharge cycleability (cycle number of 85% of the first capacity) ) ,; Presence / absence of safety valve open at the time of external short circuit No. Negative electrode material Separator Discharge capacity Cycling valve Open D-1 Compound A S-1 485 310 No D-2 Same as above S-2 490 320 No D-3 Same as above S-3 510 360 None D-4 Same as above S-4 515 345 None D-5 Same as above S-5 512 335 None D-6 Same above SC1 475 295 Open D-7 Same above SC2 480 330 Open From the above results, Compound A of the negative electrode of the present invention The performance of the battery using the battery depends on the type of separator.When a separator other than the present invention is used, the valve opens in the external short-circuit test and the contents are blown out. To contrast, in combination with the separator of the present invention it can be seen that does not occur abnormal. It has also been found that, among the separators of the present invention, particularly good results can be obtained by using a composite type separator of S-3. Furthermore, when the compound e of the negative electrode material other than the present invention is used, there is no difference in the external short circuit test regardless of which separator is used,
It was found to be unique to the negative electrode material of the present invention.

Example 2 The following results were obtained in the same manner as in Example 1. No. Negative electrode material Separator Discharge capacity Cycling valve Open D-3 Compound A S-3 510 360 None D-7 Same as above SC2 480 330 Open D13 Compound B S-3 520 370 None D14 Same as above SC2 480 315 Open D15 Compound C S-3 465 235 None D16 Same as above SC2 450 240 Open D17 Compound d S-3 520 35 Open D18 Same as above SC2 505 40 Open D19 Compound e S-3 570 15 Open D20 Same above SC2 545 15 15 Open As a result, silicon dioxide is used as a negative electrode material. It can be seen that when a material other than the present invention that does not use is used, the cycle property is remarkably inferior and the safety cannot be ensured.

Example 3 The following results were obtained in the same manner as in Example 1. No. Negative electrode material Separator Discharge capacity Cycling valve Open D-1 Compound A S-1 485 310 No D-2 Same as above S-2 490 320 No D21 Same as S-6 485 315 No D22 Same as above SC3 485 325 Open D-7 Same as SC2 480 330 Open D-4 Same as above S-4 515 345 None D-5 Same as above S-5 512 335 None D23 Same above S-7 500 315 None D-6 Same above SC1 475 295 From the above results, the separator of the present invention is: It can be seen that the ethylene component is required to be 20% by weight or more.

Example 4 The thickness of the separator S-2 was 100 μm, 125 μm,
Separators S-8 to 10 were made in the same manner except that the thickness was changed to 150 μm. When an experiment similar to that of Example 3 was performed using these separators, S-9 and S-1
The discharge capacity of the battery using 0 decreased. Further, when a discharge experiment was conducted in an environment of 0 ° C., it was found that the discharge capacity of the batteries using S-9 and S-10 was significantly reduced, and the thickness of the separator was preferably 100 μm or less.

[0052]

As in the present invention, by using a negative electrode using an amorphous oxide and a separator containing at least 20% by weight of ethylene in combination, a high discharge capacity and excellent charge / discharge cycle characteristics can be obtained. A non-aqueous secondary battery excellent in safety can be obtained.

[Brief description of drawings]

FIG. 1 shows a cross-sectional view of a cylindrical battery used in an example.

[Explanation of symbols]

 1 Gasket 2 Battery Can 3 Separator 4 Negative Sheet 5 Positive Electrode Sheet 6 Electrolyte 7 Safety Valve 8 Positive Terminal 9 PTC Element 10 Sealing Plate 11 Insulating Ring

Claims (4)

[Claims] 1. A non-aqueous secondary battery comprising a positive electrode active material, a negative electrode material, a separator and a non-aqueous electrolyte containing a lithium salt, wherein the negative electrode material is obtained by mixing and firing an oxide or chalcogenide and silicon dioxide. A non-aqueous electrolyte secondary battery, which is a crystalline compound. 2. The negative electrode material comprises silicon dioxide, Sn, G
The non-aqueous electrolyte secondary according to claim 1, which is an amorphous composite oxide obtained by mixing and firing at least one oxide of an element selected from e, Pb, Sb, and Bi. battery. 3. The non-aqueous electrolyte secondary battery according to claim 1, wherein the separator is a porous film or cloth containing at least 20% by weight of an ethylene component. 4. The separator has a thickness of 5 μm or more and 100.
The non-aqueous electrolyte secondary battery according to claim 3, wherein the non-aqueous electrolyte secondary battery has a thickness of not more than μm.