JPH07122298A - Method for electrically charging/discharging non-aqueous secondary battery - Google Patents

Abstract

PURPOSE:To improve battery voltage, electric discharging capacity, and electric discharging cycle lifetime by carrying out electric discharging down to 0.5-1.5V which is smaller than an electric charging completion voltage, followed by electric charging, in an electric charging/discharging cycle. CONSTITUTION:Two or more kinds of transition metal compounds are mixed at predetermined ratios, thus synthesizing transition metal oxide before insertion of a lithium ion. Otherwise, one or two or more kinds of transition metal compounds are mixed with a lithium compound at a molar ratio of 3.1 or less, thereby synthesizing transition metal oxide. The transition metal includes at least one kind of Ti, V, Mn, Co, Ni, Fe, Cr, Nb and Mo. One kind of the above transition materials is used as a negative electrode active material, where an electric charging completion voltage is set to 3.5-4V. Electric charging is carried out after electric discharging up to 0.5-1.5V in an electric charging/discharging cycle. Such transition metal oxide that the basic structure of crystal of a precursor is changed is used, and thereafter, the basic structure is not changed. An X-ray diffraction pattern is changed by insertion of a lithium ion, and then, it cannot be changed with repeated electric charging/discharging.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging / discharging method for a non-aqueous secondary battery having improved charging / discharging cycle characteristics.

[0002]

2. Description of the Related Art Lithium metal and lithium alloys are typical as negative electrode active materials for non-aqueous secondary batteries. When they are used, lithium metal grows in a dendritic form during charge / discharge, causing internal short circuit. , The activity of the dendritic metal itself is high,
There is a risk of ignition. On the other hand, recently, a baked carbonaceous material capable of inserting and extracting lithium has been put into practical use. This carbonaceous material is excellent in that the risk of ignition is relatively low and the charge / discharge capacity is high. However, as a drawback, since it has conductivity by itself, lithium metal may be deposited on the carbonaceous material during overcharging or rapid charging, and as a result, dendritic metal may be deposited. . In order to avoid this, we have devised a charger or adopted a method of reducing the amount of positive electrode active material to prevent overcharge.
In the latter method, the amount of active material is limited, so the discharge capacity is also limited. Further, since the carbonaceous material has a relatively low density, the discharge capacity per volume is small. Therefore, the discharge capacity is limited in terms of both the limitation of the amount of active material and the small capacity per volume.

On the other hand, as negative electrode active materials other than lithium metal, lithium alloys, and carbonaceous materials, TiS ₂ and LiTiS ₂ capable of inserting and extracting lithium ions.
(U.S. Pat. No. 3,983,476), W with rutile structure
O ₂ (US Pat. No. 4,198,476), Lix Fe
Spinel compounds such as (Fe ₂ ) O ₄ (JP-A-58-2
No. 20362), electrochemically synthesized Fe ₂ O
₃ lithium compounds (U.S. Pat. No. 4,464,447)
No.), a lithium compound of Fe ₂ O ₃ (JP-A-3-112)
070), Nb ₂ O ₅ (Japanese Patent Publication No. 62-59412).
No. 2, JP-A-2-82447), iron oxide, Fe
O, Fe ₂ O ₃ , Fe ₃ O ₄ , cobalt oxide, CoO,
Co ₂ O ₃ and Co ₃ O ₄ (JP-A-3-291862) are known.

A positive electrode active material which is a metal chalcogenide
As a combination of quality and negative electrode active material, TiS₂And LiTi
S₂(US Pat. No. 983,476), chemically synthesized.
Li 0.1 V₂O_FiveAnd LiMn1-s Mes O₂(0.
1 <s <1, Me = transition metal; JP-A-63-21002
No. 8), chemically synthesized Li_0.1V₂O_0.1When
LiCo_1-SFes O₂(S = 0.05 to 0.3;
63-212164), chemically synthesized L
i_0.1V₂O_FiveAnd LiCo₁-_SNis O₂(S = 0.5
.About.0.9; JP-A-1-294364), V₂O_Five
And Nb₂O_Five+ Lithium metal (JP-A-2-82447)
Gazette), V₂O_FiveAnd TiS₂And electrochemically synthesized
Lix Fe₂O₃(U.S. Pat. No. 4,464,447;
Journal of Power Sources, Volume 8, 289
(1982, 1982), LiNi is used as a positive electrode active material and a negative electrode active material.
x Co₁-x O₂(0 ≦ x <1; JP-A-1-120765
In the specification, the positive electrode active material and the negative electrode active material are described in Examples.
The substances are described as the same compound. ), LiCoO₂
Or LiMn₂O_FourAnd iron oxide, FeO, Fe
₂O ₃, Fe₃O_Four, Cobalt oxide, CoO, Co₂O
₃Or Co₃O_Four(Japanese Patent Laid-Open No. 3-291862
News) is known.

Among these, the non-aqueous secondary battery using a lithium-containing transition metal oxide as a negative electrode active material is a negative electrode active material that exhibits the above-mentioned high safety, high discharge capacity and high battery voltage (3V class). Although it is promising as a substance, it has a very big problem in practical use that it is inferior in cycle characteristics, and improvement in cycle characteristics has been strongly desired.

[0006]

An object of the present invention is to provide a non-aqueous secondary battery having a high battery voltage, a high discharge capacity (high energy density) and a long charge / discharge cycle life, and a charge / discharge method thereof. It is in.

[0007]

[Means for Solving the Problems] The above-mentioned problems are solved by the negative electrode active material.
Quality is Lix MOj (where M is Ti, V, Mn, C
at least selected from o, Fe, Ni, Nb and Mo
Represents a kind of transition metal, x is 0.17 to 11.25
Range and j is in the range 1.6 to 4.1)
Is a lithium-containing transition metal oxide represented by
The active material is Li _yNO_z(However, N is at least one
Represents a transition metal and at least one of the transition metals is C
at least one selected from o, Mn, Ni, V and Fe
Represents a kind of transition metal, and y is in the range of 0.2 to 1.2.
And z is in the range of 1.4 to 3)
It is a transition metal oxide containing and has an end-of-charge voltage of 3.5-
With non-aqueous secondary battery set to 4.7V, for charge / discharge cycle
Then, charge the battery after discharging it to 0.5 to 1.5V.
Achieved by and.

The transition metal referred to in the present invention has an element number of 2.
From 1 of Sc to Zn of element number 30 and Y of element number 39 to Cd of element number 48 and La of element number 57 to Hg of element number 80.

The non-aqueous secondary battery of the present invention has a basic structure composed of a positive electrode active material, a negative electrode active material and a non-aqueous electrolyte containing a lithium salt. The negative electrode active material is a transition metal oxide that may contain lithium, or is obtained by inserting lithium ions into the transition metal oxide, preferably a lithium-containing transition It is obtained by inserting (preferably electrochemically inserting) lithium ions into the metal oxide.

A transition metal oxide used in the present invention before insertion of lithium ions (hereinafter referred to as a negative electrode active material precursor).
Is prepared by mixing two or more kinds of transition metal compounds at a desired ratio, or a lithium compound and one or more kinds of transition metal compounds are mixed in a lithium compound / total transition metal compound molar ratio of 3.1 or less. It is preferable to mix them so as to be synthesized. However, transition metals include Ti, V, Mn, and C.
The transition metal contains at least one of o, Ni, Fe, Cr, Nb, and Mo. Further, the negative electrode active material precursor is preferably synthesized by mixing a lithium compound and a transition metal compound so that the molar ratio of lithium compound / total transition metal compound is 0.2 to 3.1. Here, the transition metal is the transition metal containing at least one of Ti, V, Mn, Co, Ni and Fe.

At least one of the transition metal oxides that is the precursor of the negative electrode active material of the present invention is LipMOj (provided that M
Represents at least one transition metal and at least one of the transition metals is Ti, V, Mn, Co, Ni, F
e, Cr, Nb, and Mo, p is in the range of 0 to 3.1, and j is in the range of 1.6 to 4.1).

The negative electrode active material precursor further comprises a Lip
M ₁ q1 M ₂ q2 ・ ・ ・ Mnqn Oj (However, M ₁ M ₂・ ・ ・
Each of Mn represents the transition metal, at least one of which represents Ti, V, Mn, Co, Ni or Fe, and p is in the range of 0 to 3.1, q1 + q2.
+ ... + qn = 1, n is in the range 1-10, and j is in the range 1.6-4.1). Further, in the above equation, p is 0.2 to
More preferably, it is in the range 3.1, n is in the range 1 to 4, and j is in the range 1.8 to 4.1. In particular, in the above formula, p is in the range of 0.2 to 3.1, n is in the range of 1 to 3, and j is 1.8 to
It is preferably in the range of 4.1.

As described above, the negative electrode active material precursor of the present invention is a transition metal having a valence of 5+ to 6+ stably existing (eg,
V, Cr, Nb, Mo) is preferably contained in order to obtain a high discharge capacity.

As the negative electrode active material precursor containing V or the like, Lip M ₁ q1 M ₂ q2 ... MnqnXqvOj (however,
M is a transition metal, X is V, Cr, Nb, Mo, p is in the range of 0 to 3.1, q1 + q2 + ...
+ Qn + qv = 1, n is in the range 1 to 9 and j is in the range 1.3 to 4.1). Further, from the viewpoint of obtaining a high discharge capacity, it is particularly preferable that these negative electrode active material precursors contain at least V. The negative electrode active material precursor containing V is L
ip Mq1 Mq2V _1- (q1 + q2) Oj (where M is a transition metal, p is in the range of 0.2 to 3.1, q1 + q2 is in the range of 0 to 0.7, and j is It is more preferably in the range of 1.3 to 4.1). Further, the negative electrode active material precursor containing V is Lip Coq V ₁ -q Oj
, Lip Niq V ₁ -q Oj (where p is 0.3 to 2.
2, q is in the range of 0.02-0.7,
And j is in the range of 1.5 to 2.5) is most preferable.

Examples of particularly preferable negative electrode active material precursors in the present invention include Lip CoVO ₄ and Lip NiVO ₄ (where p is in the range of 0.3 to 2.2). Here, the above p value is a value before the start of charging / discharging, and increases / decreases due to charging / discharging. In addition, the negative electrode active material is one in which the content of lithium is increased in the precursor composition formula. In the general formula (eg, Lip MOj) shown in the present invention, the transition metal M
Since the sum of the above is 1, the number may be an integer multiple in the case of a plurality of transition metals or in a crystallographic composition formula.

The most preferred negative electrode active material precursor of the present invention
Specific examples are given below, but are limited to these compounds
Not a thing. For example, LiVO₃.₁, LiTi
O₂.₃, CoVO₃.₇, LiCoVO_Four, LiCo₀._Five
V₀._FiveO₂.₁, LiNiVO_Four.₀, Li₀.₇₅Ni₀._FiveV
₀._FiveO₂.₁, Li₁.₇₅Ni₀._FiveV₀._FiveO₂._Four, LiTi
₀._FiveV₀._FiveO₂.₉, LiMn₀._FiveV₀._FiveO₂._Five, LiF
e₀._FiveMn₀._FiveO₂.₁, LiCo₀._{twenty five}V₀.₇₅O₂.₈, L
iNi₀._{twenty five}V₀.₇₅O₂.₈, LiNi₀.₀₅V₀.₉₅O₃.₁,
LiFe₀.₀₅V₀.₉₅O₃.₁, LiMn₀.₀₅V₀.
₉₅O₃.₀, LiCa₀.₀₅V₀.₉₅O₃.₂, LiCo₀.₇₅V
₀._{twenty five}O₁.₉, LiMn₀._{twenty five}Ti₀._FiveV₀._{twenty five}O₂.₆, Li
Cr₀.₀₅V₀.₉₅O₃.₂, LiNb_0.05V_0.95O_3.1, L
iMo_0.05V_0.95O_3.0, Li_0.8Na_0.2Co_0.5V
_0.5O_2.1, Li_0.95Rb_0.05Ni_0.5V_0.5O _2.2,
Li_0.9K_0.2Co_0.5V_0.5O_2.2, Li_0.85Ba
_0.15Ni_0.5V_0.5O_2.2, Li_0.9Co_0.4A_10.1V
_0.5O_2.1, LiCo_0.45Ga_0.05V_0.5O _2.2, Li
_0.9Ni_0.2In_0.3V_0.5O_2.3, Li_1.05Co_0.4
T_10.1V₀._FiveO_2.3, Li_1.03Ge_0.5V_0.5O_2.3,
Li_0.98Co_0.25Pb_0.25V_0.5O₂. ₁, LiCo_0.5
Bi_0.05V_0.45O_2.1, Li_0.96Ni_0.25Zr_0.25V
_0.5O₂. ₂, LiCo_0.2Ni_0.3Ag_0.05V_0.45O
_2.1, LiCo_0.4Zr_0.1V_0.5O_2.0, Li_1.01C
o_0.4La_0.1V_0.5O_2.1, LiNi_0.2Cd_0.3V
_0.5O_2.1, LiCo_0.25Ce_0.25V_0.5O_2.2, Li
_1.03Co_0.2Sm_0.3V_0.5O_2.1, Li_0.85Na_0.15
Co_0.4Ge_0.2V_0.4O_2.1Can be mentioned.
The oxygen number is the weight of the compound before firing and the weight after firing.
It is the value obtained from Therefore, is the oxygen number accurate in the measurement method?
It is necessary to add an error of -10 to 10% of the above value.
It

The negative electrode active material of the present invention is obtained by inserting lithium ions into the above negative electrode active material precursor. Therefore,
The Lip of the transition metal oxide that may contain lithium as the negative electrode active material precursor is Lix. That is, x is generally in the range of 0.17 to 11.25 (the lithium increase x-p due to lithium ion insertion is generally 0.
The range is from 17 to 8.15). For example, the negative electrode active material used in the present invention obtained by inserting lithium ions into Lip MOj of the preferred negative electrode active material precursor is Lix MOj (where M represents at least one transition metal and At least one is Ti,
It is selected from V, Mn, Co, Fe, Ni, Nb and Mo, p is in the range of 0 to 3.1, and x is 0.
Is in the range 17-11.25, and j is 1.6-
It is composed of at least one lithium-containing transition metal oxide represented by (4. 1). x is preferably in the range of 0.26 to 10.2, and x is 0.3.
The range of 4 to 9.3 is preferable. Further, a preferred negative electrode active material is Lix Mq V ₁ -q Oj (where M represents a transition metal, p is in the range of 0 to 3.1, and x is 0.17 to
In the range 8.15, q in the range 0-0.7,
And j is in the range of 1.3 to 4.1).
x is preferably in the above range.

The negative electrode active material of the present invention is preferably obtained by inserting lithium ions into a negative electrode active material precursor of a transition metal oxide and / or a lithium-containing transition metal oxide as follows. For example, a method of reacting with lithium metal, a lithium alloy, butyl lithium, or the like, or a method of electrochemically inserting lithium ions is preferable. In the present invention, it is particularly preferable to electrochemically insert lithium ions into the transition metal oxide that is the negative electrode active material precursor. Above all, it is most preferable to use a lithium-containing transition metal oxide as a negative electrode active material precursor and electrochemically insert lithium ions into the transition metal oxide. As a method of electrochemically inserting lithium ions, a target lithium-containing transition metal oxide (a negative electrode active material precursor in the present invention) is included as a positive electrode active material, and lithium metal and a lithium salt are included as a negative electrode active material. It can be obtained by discharging a redox system composed of a non-aqueous electrolyte (for example, an open system (electrolysis) or a closed system (battery)). Furthermore, a redox system comprising a lithium-containing transition metal oxide as a positive electrode active material, a negative electrode active material precursor having a composition formula different from that of the positive electrode active material as a negative electrode active material, and a nonaqueous electrolyte containing a lithium salt (for example, an open system ( Electrolysis) or closed systems (batteries)) are preferred.

The insertion amount of lithium ions is not particularly limited, but is 27 to 1340 mA per 1 g of the negative electrode active material precursor.
h (corresponding to 1 to 50 mmol) is preferable. Especially 40 to 1
070 mAh (corresponding to 1.5 to 40 mmol) is preferable.
And 54-938 mAh (2-35 mmol equivalent) is the most preferable. The use ratio of the positive electrode active material and the negative electrode active material is not particularly limited, but it is preferable to set them so that the effective equivalents are equal to each other (the effective equivalent is an equivalent that can substantially maintain the cycle property). ). At that time, it is also preferable to increase the amount of either the positive electrode active material or the negative electrode active material.

In the present invention, it is preferable that a lithium-containing transition metal oxide in which the basic structure of the crystal of the precursor is changed is used as the negative electrode active material, and the changed basic structure is not changed by charge and discharge. That is, it is preferable that the X-ray diffraction pattern of the negative electrode active material precursor of the present invention changes due to the insertion of lithium ions, and thereafter it does not substantially change even after repeated charging and discharging.

The positive electrode active material used in the present invention may be a transition metal oxide capable of reversibly occluding and releasing lithium ions, but a lithium-containing transition metal oxide is preferable. Preferred lithium-containing transition metal oxide positive electrode active materials include lithium-containing Ti, V, Cr, Mn, Fe and Co.
The oxide containing Ni, Cu, Mo and / or W can be mentioned. It is preferable that the positive electrode active material and the negative electrode active material have different composition formulas.

The lithium-containing transition metal oxide, which is the positive electrode active material of the present invention, contains a lithium compound and one or more transition metal compounds in a molar ratio of lithium compound / total transition metal compound of 0.3 to 2. It is preferable that they are mixed and synthesized so as to be 0.2 (however, the transition metal is Ti,
At least one selected from V, Cr, Mn, Fe, Co, Ni, Mo and W). Furthermore, as the transition metal,
It is preferably at least one selected from V, Cr, Mn, Fe, Co and Ni.

The lithium-containing transition metal oxide, which is the positive electrode active material of the present invention, is Liy NOz (where M is Co,
A transition metal containing at least one selected from Mn, Ni, V and Fe, y is in the range of 0.3 to 1.2, and z is in the range of 1.4 to 3).

Preferred Lithium-Containing Metal Oxides of the Invention
As a positive electrode active material of Liy CoO₂, Liy NiO
₂, Liy Coa Ni₁-a O₂, Liy Cob V₁-b O
z, Liy Cob Fe₁-b O₂, Liy Mn₂O_Four, L
iy Mnc Co₂-c O_Four, Liy Mnc Ni₂-c O_Four,
Liy Mnc V₂-c O_FourAnd Liy Mnc Fe₂-c
O _Four, And Liy Mn₂O_FourAnd MnO₂Mixture with,
Li₂yMn₂O₃And MnO ₂Mixture with, and Liy M
n₂O_Four, Li₂yMn₂O₃And MnO₂Mixture with
, Y is in the range of 0.5 to 1.2, and a is 0.1 to
Is in the range of 0.9 and b is in the range of 0.8 to 0.98.
, C is in the range of 1.6 to 1.96, and 0z is
2.01 to 5).

Further preferred positive electrode active materials for lithium-containing metal oxides of the present invention include LiyCoO ₂ and Liy N
iO ₂ , Liy Coa Ni ₁ -a O ₂ , Liy Cob V _1-
b Oz, Liy Cob Fe ₁ -b O ₂ , Liy Mn
₂ O ₄ , Liy Mnc Co ₂ -c O ₄ , Liy Mnc Ni ₂
-c O ₄ , Liy Mnc V ₂ -c O ₄ , Liy Mnc Fe ₂
-cO ₄ (however, y is in the range of 0.7 to 1.04, a
Is in the range of 0.1 to 0.9, and b is 0.8 to 0.98.
, C is in the range 1.6 to 1.96, and z is in the range 2.01 to 2.3).

The most preferable lithium-containing transition metal oxides of the present invention are Liy CoO ₂ and Liy NiO.
₂ , Liy Coa Ni ₁ -a O ₂ , Liy Mn ₂ O ₄ , L
iyCob V ₁ -b Oz (where y is in the range of 0.7 to 1.1, a is in the range of 0.1 to 0.9, and b is 0.
9 to 0.98 and z is 2.01-2.
3). Furthermore, y is in the range 0.7 to 1.04, a is in the range 0.1 to 0.9, b is in the range 0.9 to 0.98, and z is 2.02. It is preferably in the range of to 2.3. Here, the above y value is a value before the start of charging / discharging,
Increases / decreases due to charge / discharge.

Examples of particularly preferred compounds used in the present invention
Are listed below, but are not limited thereto.
For example, LiCoO₂, LiNiO₂, LiCo₀._FiveN
i₀. _FiveO₂, LiCo_0.95V_0.05O_2.05, LiMn
O₂, LiMn₂O_FourCan be mentioned. In the present invention
The oxide of the positive electrode active material used may be crystalline or amorphous.
Good, but crystalline compounds are preferred.

In the present invention, "the positive electrode active material and the negative electrode active material have different composition formulas" means the following: Different combinations of metal elements, and 2. Positive electrode active material Liy Cob V ₁ -b Oz and negative electrode active material L
The example of ix Coq V ₁ -q Oj means that the values of y and x, b and q, and z and j are not equal at the same time. In particular, this means that b and q and z and j are not equal at the same time. The positive electrode active material and the negative electrode active material used in the present invention are preferably combined with compounds having different standard redox potentials.

The positive electrode active material of the present invention comprises a method of chemically inserting lithium ions into a transition metal oxide, a method of electrochemically inserting lithium ions into a transition metal oxide, and a mixture of a lithium compound and a transition metal compound. , Can be synthesized by firing.

In synthesizing the positive electrode active material of the present invention, as a method of inserting lithium ions into a transition metal oxide, a method of reacting lithium metal, a lithium alloy or butyllithium with a transition metal oxide is preferable. . The positive electrode active material used in the present invention is particularly preferably synthesized by mixing a lithium compound and a transition metal compound and firing.

Further, the firing temperature of the negative electrode active material of the present invention or its precursor may be a temperature at which a part of the mixed compound used in the present invention is decomposed and melted, for example, 25
0 to 2000 ° C. is preferable, and 300 to 1500 ° C. is particularly preferable. Alternatively, the synthesis may be performed in a stepwise heating / cooling pattern of two or more steps. The firing gas atmosphere used in the present invention is not particularly limited, but the positive electrode active material is preferably in air or in a gas containing a large proportion of oxygen (for example, about 30% or more). In the negative electrode active material or its precursor, it is in air, in a gas having a low oxygen content (for example, about 10% or less), in a gas having a high oxygen content (for example, about 30% or more), or an inert gas (nitrogen gas, It can be preferably fired in any of argon gas). Further, the negative electrode active material or the precursor thereof used in the present invention may be synthesized by simultaneously mixing the starting materials and then firing, or may be synthesized by stepwise mixing and firing in two or more steps. Good. For example, when synthesizing a LiCoVO4 as the negative electrode active material precursor, Li compound is a raw material compound, Co compounds, may be fired in one step by both mixing the V compound, a Co compound and a V compound Co ₂ V It can also be obtained by synthesizing ₂₀₇ by firing, mixing it with a Li compound, and further firing.

The ratio of the positive electrode active material and the negative electrode active material used in the non-aqueous secondary battery of the present invention can be arbitrarily set depending on the types of active materials to be combined.

The non-aqueous secondary battery of the present invention is discharged to a battery voltage of 0.5 to 1.5 V during the charge / discharge cycle, and the following two methods can be mentioned as this method. (1) The range of the discharge end voltage used is 1.5 V or more,
A method of setting to 3.0 V or less, discharging once to 0.5 to 1.5 V before charging, and then discharging in the next cycle. In this case, the voltage may be discharged to this voltage each time during the charge / discharge cycle, or after 0.5 to 1.5 after repeating the cycle several times.
You may discharge to V. In the latter case, it is preferable to incorporate an operation of discharging to 0.5 to 1.5 V about once within 20 cycles in consideration of the battery capacity decrease accompanying the cycle. (2) The range of the discharge end voltage used is 0.5 V or more,
How to set less than 1.5V. 0.5 ~ 1.5V above
In the discharge up to, a discharge up to 0.7 to 1.5 V is preferable, and a discharge up to 0.8 to 1.4 V is particularly preferable. If the discharge end voltage is lower than 0.5 V, the current collector may be dissolved, and if it is higher than 1.5 V, the cycle property is deteriorated, which is not preferable.

The end-of-charge voltage is preferably in the range of 3.5 to 4.7 V so that a battery voltage of 3 V class can be exhibited.
3.7-4.5V is more preferable and 3.8-4.4V is preferable.
Is particularly preferable. When it is lower than 3.5 V, the battery voltage becomes low, and when it is higher than 4.7 V, the positive electrode active material and the electrolytic solution may be decomposed, both of which are not preferable.

The negative electrode active material or the precursor thereof and the positive electrode active material of the present invention are preferably synthesized by firing a mixture of a lithium compound and a transition metal compound described below. Examples of the lithium compound include oxygen compounds, oxyacid salts and halides. As the transition metal compound, a monovalent to hexavalent transition metal oxide, the same transition metal salt, or the same transition metal complex salt is used.

Preferred lithium compounds which can be used in the present invention include lithium oxide, lithium hydroxide, lithium carbonate, lithium nitrate, lithium sulfate, lithium sulfite, lithium phosphate, lithium tetraborate, lithium chlorate and perchloric acid. Lithium, lithium thiocyanate,
Lithium formate, lithium acetate, lithium oxalate, lithium citrate, lithium lactate, lithium tartrate, lithium pyruvate, lithium trifluoromethanesulfonate, lithium tetraborate, lithium hexafluorophosphate, lithium fluoride, lithium chloride, bromide Examples thereof include lithium and lithium iodide.

Preferred transition metal compounds that can be used in the present invention include TiO ₂ , lithium titanate,
Acetylacetonato titanyl, titanium tetrachloride, titanium tetraiodide, titanyl ammonium oxalate, VOd (d = 2 to
2.5 d = 2.5 compound is vanadium pentoxide), V
Od lithium compound, vanadium hydroxide, ammonium metavanadate, ammonium orthovanadate, ammonium pyrovanadate, vanadium oxosulfate, vanadium oxytrichloride, vanadium tetrachloride, lithium chromate, ammonium chromate, cobalt chromate, chromium acetylacetoacetate Naates, MnO ₂ , Mn ₂ O ₃ , manganese hydroxide, manganese carbonate, manganese nitrate, manganese sulfate, ammonium manganese sulfate, manganese sulfite, manganese phosphate, manganese borate, manganese chlorate, manganese perchlorate, manganese thiocyanate, formic acid. Manganese, manganese acetate, manganese oxalate, manganese citrate, manganese lactate, manganese tartrate, manganese stearate, manganese fluoride, manganese chloride, manganese bromide, manganese iodide, manganese acetyl Acetonate, iron oxide (2, 3
Valence), iron trioxide, iron hydroxide (2,3 valence), iron chloride (2,3 valence), iron bromide (2,3 valence), iron iodide (2,3 valence)
Value), iron sulfate (2,3 value), ammonium iron sulfate (2,3)
Trivalent), iron nitrate (2,3 valent) iron phosphate (2,3 valent), iron perchlorate, iron chlorate, iron acetate (2,3 valent), iron citrate (2,3 valent), citric acid Ammonium ferric acid (2,3 valent),
Iron oxalate (2,3 valent), ammonium iron oxalate (2,3)
Price),

CoO, Co ₂ O ₃ , Co ₃ O ₄ , LiC
oO ₂ , cobalt carbonate, basic cobalt carbonate, cobalt hydroxide, cobalt sulfate, cobalt nitrate, cobalt sulfite, cobalt perchlorate, cobalt thiocyanate, cobalt oxalate, cobalt acetate, cobalt fluoride, cobalt chloride,
Cobalt bromide, cobalt iodide, hexaammine cobalt complex salt (as salts, sulfuric acid, nitric acid, perchloric acid, thiocyanic acid, oxalic acid, acetic acid, fluorine, chlorine, bromine, iodine), nickel oxide, nickel hydroxide, nickel carbonate, Basic nickel carbonate, nickel sulfate, nickel nitrate, nickel fluoride, nickel chloride, nickel bromide, nickel iodide, nickel formate, nickel acetate, nickel acetylacetonate, copper oxide (divalent), copper hydroxide, Copper sulfate, copper nitrate, copper phosphate, copper fluoride, copper chloride, ammonium chloride copper, copper bromide, copper iodide, copper formate, copper acetate, copper oxalate, copper citrate, niobium oxychloride, niobium pentachloride, penta Niobium iodide, niobium monoxide, niobium dioxide, niobium trioxide, niobium pentoxide, niobium oxalate, niobium methoxide, niobium ethoxide, niobium propoxide, niobium oxide Kishido, lithium niobate,
MoO ₃ , MoO ₂ , LiMo ₂ O ₄ , molybdenum pentachloride, ammonium molybdate, lithium molybdate, ammonium molybdophosphate, molybdenum acetylacetonate oxide, WO ₂ , WO ₃ , tungstic acid, ammonium tungstate, ammonium tungstophosphate. Can be mentioned.

Particularly preferred which can be used in the present invention
As a transition metal compound, TiO 2 ₂, Titanyl oxalate
Limonium, VOd (d = 2-2.5), VOd
Um compounds, ammonium metavanadate, MnO₂,
Mn₂O₃, Manganese hydroxide, manganese carbonate, man nitrate
Cancer, ammonium manganese sulfate, manganese acetate, oxalic acid
Manganese, manganese citrate, iron oxide (2,3 valent), four
Iron trioxide, iron hydroxide (2,3 valent), iron acetate (2,3)
Value), iron citrate (2,3 value), iron citrate ammoniu
(2,3 values), iron oxalate (2,3 values), iron oxalate ammonium
Um (2,3 valence), CoO, Co₂O₃, Co₃O_Four,
LiCoO₂, Cobalt carbonate, basic cobalt carbonate, water
Cobalt oxide, cobalt oxalate, cobalt acetate, nickel oxide
Gel, nickel hydroxide, nickel carbonate, basic nitric carbonate
Kell, nickel sulfate, nickel nitrate, nickel acetate, acid
Copper (1 and 2), copper hydroxide, copper acetate, copper citrate, M
oO₃, MoO₂, LiMo₂O_Four, WO₂, WO₃To
Can be mentioned.

Particularly preferred which can be used in the present invention
As a combination of a lithium compound and a transition metal compound, an acid
Lithium fluoride, lithium hydroxide, lithium carbonate, lithium acetate
Lithium of um and VOd (d = 2-2.5), VOd
Compound, ammonium metavanadate, MnO₂, Mn₂
O₃, Manganese hydroxide, manganese carbonate, manganese nitrate,
Iron oxide (2,3 valence), triiron tetraoxide, iron hydroxide (2,3)
Valent) iron acetate (2,3 valent), iron citrate (2,3 valent),
Ammonium iron enoate (2,3 valent), iron oxalate (2,3)
Valence), ammonium iron oxalate (2,3 valence), CoO, Co
₂O₃, Co₃O_Four, LiCoO₂, Cobalt carbonate, salt
Basic cobalt carbonate, cobalt hydroxide, cobalt sulfate, glass
Cobalt acid, nickel oxide, nickel hydroxide, nickel carbonate
Kell, basic nickel carbonate, nickel sulfate, nickel nitrate
, Nickel acetate, MoO₃, MoO ₂, LiMo₂O
_Four, WO₃Can be mentioned.

In addition to lithium compounds and transition metal compounds,
In general, compounds that enhance ionic conductivity, such as Ca ²⁺ ,
(For example, calcium carbonate, calcium chloride, calcium oxide, calcium hydroxide, calcium sulfate, calcium nitrate, calcium acetate, calcium oxalate, calcium citrate, calcium phosphate) or amorphous formation containing P, B, Si Agents (eg P ₂ O ₅ , Li ₃ P
O ₄ , H ₃ BO ₃ , SiO _{2 and the} like) may be mixed and fired. In addition, alkali metal ions such as Na, K and Mg and / or Sn, Al, Ga, Ge, Ce and I
You may mix with a compound containing n, Bi, etc. (for example, each oxide, hydroxide, carbonate, nitrate, etc.), and bake. Among them, calcium carbonate or P ₂ O ₅
It is preferable to mix with and fire. The addition amount is not particularly limited, but 0.2 to 10 mol% is preferable.

The average particle size of the positive electrode active material, the negative electrode active material or the precursor thereof used in the present invention is not particularly limited, but the average particle size (cumulative distribution 50% particle size) is 0.03 to.
50 μm is preferable. A known crusher or classifier can be used to obtain a predetermined particle size. For example,
Mortar, ball mill, vibrating ball mill, satellite ball mill,
A swirling airflow type jet mill, a sieve, etc. can be mentioned.

The chemical formula of the compound obtained by firing can be calculated from an inductively coupled plasma (ICP) emission spectroscopic analysis method as a measuring method and a weight difference between the powders before and after firing as a simple method.

Both the positive electrode active material and the negative electrode active material used in the present invention obtained as described above are considered to be compounds that occlude and release lithium ions by charge and discharge and change the valence of the transition metal. . Therefore, the negative electrode active material of the present invention is a negative electrode active material having a concept that is fundamentally different from the method of depositing and dissolving lithium by charging and discharging, like a metal negative electrode active material such as lithium metal or lithium alloy. Also,
Similarly, when compared to carbonaceous compounds, carbon is not a compound that changes its valence clearly, and also has high conductivity,
It is a compound that easily deposits lithium metal during charging. Therefore, the negative electrode active material of the present invention is a negative electrode active material whose concept is fundamentally different from that of lithium metal or carbonaceous material.

Materials that can be used with the negative electrode active material of the present invention include lithium metal and lithium alloys (Al, Al-
Mn (US Pat. No. 4,820,599), Al-Mg
(JP-A-57-98977), Al-Sn (JP-A-63-6742), Al-In, Al-Cd.
(JP-A-1-144573) or the like, or a calcined carbonaceous compound capable of inserting and extracting lithium ions or lithium metal (for example, JP-A-58-209864, JP-A-61-214417, and JP-A-62-62). -88269
JP-A-62-216170, JP-A-63
-13282, JP-A-63-24555,
JP-A-63-112247, JP-A-63-121
257, JP-A-63-155568, JP-A-63-276873, and JP-A-63-31482.
1, JP-A-1-204361, JP-A-1-204361
221859, JP-A-1-274360, etc.). The purpose of using the lithium metal or lithium alloy together is to insert lithium ions into the battery, and does not utilize the dissolution / precipitation reaction of lithium metal or the like as the battery reaction.

A conductive agent, a binder, a filler and the like can be added to the electrode mixture. 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.), artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers and metals (copper, nickel, aluminum, silver (JP-A-63) -1
No. 48554), powders, metal fibers, or polyphenylene derivatives (Japanese Patent Laid-Open No. 59-20971) can be included as one kind or a mixture thereof. The combined use of graphite and acetylene black is particularly preferred. The amount added is not particularly limited, but is 1
-50% by weight is preferable, and 2-30% 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 a polysaccharide, a thermoplastic resin and a polymer 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. As the filler, any fibrous material that 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 preferably 0 to 30% by weight.

The electrolyte is generally composed of a solvent and a lithium salt (anion and lithium cation) which is soluble in the solvent. As the solvent, propylene carbonate, ethylene carbonate, butylene carbonate,
Dimethyl carbonate, diethyl carbonate, γ-butyrolactone, methyl formate, methyl acetate, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dimethylsulfoxide, 1,3-dioxolane, formamide, dimethylformamide, dioxolane, acetonitrile, nitromethane, Ethyl monoglyme, phosphoric acid triester (JP-A-60-23973)
JP-A-61-4170.
JP-A-62-1577.
1, JP-A-62-22372, JP-A-62-62
-108474), sulfolane (JP-A-62-3)
1959), 3-methyl-2-oxazolidinone (JP-A-62-44961), propylene carbonate derivative (JP-A-62-290069, JP-A-6-290069).
2-290071), tetrahydrofuran derivative (JP-A-63-32872), ethyl ether (JP-A-63-62166), 1,3-propanesultone (JP-A-63-102173). Aprotic organic solvents such as, and these are used alone or in combination of two or more. Examples of the cation of a lithium salt that dissolves in these solvents include ClO
_{^{4 -, BF 4 -, PF}} 6 -, CF 3 SO 3 -, CF 3 C
O ₂ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , (CF ₃ SO ₂ ) _{2
^{N -, B 10 Cl 10 2-}} ( JP 57-74974 JP), (1,2-dimethoxyethane) ₂ ClO ₄ ^- (JP 57-74977 JP), lower aliphatic carboxylic acid ion ( JP-A-60-41773), AlCl ₄
^{-, Cl -, Br -,} I - ( JP 60-247265
No.), an anion of a chloroborane compound (JP-A-61)
165957) and tetraphenyl borate ion (JP-A-61-214376).
These 1 type (s) or 2 or more types can be used.
Among them, propylene mosquitoes - BONNET - DOO or ethylene carbonate and 1,2-dimethoxyethane and / or LiCF ₃ SO ₃ in a mixture of diethyl carbonate, Li
An electrolyte containing ClO ₄ , LiBF ₄ and / or LiPF _6, and a mixed solution of ethylene carbonate, diethyl carbonate and butylene carbonate, LiCF
Electrolytes containing ₃ SO ₃ , LiClO ₄ , LiBF ₄ and / or LiPF ₆ are preferred.

The amount of these electrolytes to be added into the battery is not particularly limited, but a necessary amount can be used depending on the amount of the positive electrode active material or the negative electrode active material and the size of the battery. The volume ratio of the solvent is not particularly limited, but in the case of a mixed solution of propylene carbonate or ethylene carbonate and 1,2-dimethoxyethane and / or diethyl carbonate, 0.4 / 0.6 to 0.6 / 0.4 ( The mixing ratio when 1,2-dimethoxyethane and diethyl carbonate are used together is preferably 0.4 / 0.6 to 0.6 / 0.4). 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. 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 N
_{I 2, Li 3 N-LiI} -LiOH, LiSiO 4, L
iSiO ₄ -LiI-LiOH (JP-A-49-8189)
9 _{JP), xLi 3 PO 4 - (} 1-x) Li 4 SiO
₄ (Japanese Patent Laid-Open No. 59-60866), Li ₂ SiS ₃
(JP-A-60-501731), phosphorus sulfide compounds (JP-A-62-82665) and the like are effective.

In the organic solid electrolyte, a polyethylene oxide derivative or a polymer containing the derivative (JP-A-63-1).
35447), polypropylene oxide derivatives or polymers containing these derivatives, polymers containing ion dissociative groups (JP-A-62-254302, JP-A-6-254302).
2-254303, JP-A-63-193954), a mixture of a polymer containing an ion dissociative group and the aprotic electrolyte (US Pat. No. 4,792,504,
U.S. Pat. No. 4,830,939, JP-A-62-223
75, JP 62-22376, and JP 6
3-22375, JP-A-63-22776, JP-A-1-95117), a phosphoric acid ester polymer (JP-A-61-256573), and a polymer containing an aprotic polar solvent. Matrix material (US Pat. No. 4,822,70, US Pat. No. 4,83
0,939, JP-A-63-239779, Japanese Patent Application No. 2-30318, and Japanese Patent Application No. 2-78531) are effective. Furthermore, there is also a method of adding polyacrylonitrile to the electrolytic solution (JP-A-62-278774).
Issue). Further, a method of using an inorganic and organic solid electrolyte in combination (Japanese Patent Laid-Open No. 60-1768) is also known.

As the separator, an insulating thin film having a large ion permeability and a predetermined mechanical strength is used. A sheet or non-woven fabric made of olefin polymer such as polypropylene or glass fiber or polyethylene is used because of its resistance to organic solvent and hydrophobicity. The pore size of the separator is in the range generally used for batteries. For example, 0.01 to 10 μ
m is used. The thickness of the separator is generally within the range for batteries. For example, 5 to 300 μm is used.

Other compounds may be added to the electrolyte for the purpose of improving discharge and charge / discharge characteristics. For example, pyridine (JP-A-49-108525), triethylphosphite (JP-A-47-4376), triethanolamine (JP-A-52-72425), cyclic ether (JP-A-57-57425). 152684), ethylenediamine (JP-A-58-87777), n-glyme (JP-A-58-87778), hexaphosphoric acid triamide (JP-A-58-8777).
9), nitrobenzene derivatives (JP-A-58-21)
No. 4281), sulfur (JP-A-59-8280), quinoneimine dye (JP-A-59-68184), N-substituted oxazolidinone and N, N'-substituted imidazolidinone (JP-A-59-154778). Gazette), ethylene glycol dialkyl ether (JP-A-59-20)
No. 5167), quaternary ammonium salts (Japanese Patent Laid-Open No. Sho 60).
-30065), polyethylene glycol (JP-A-60-41773), pyrrole (JP-A-60-).
79677), 2-methoxyethanol (JP-A-60-
89075), AlCl3 (JP-A-61-884).
No. 66), a monomer of a conductive polymer electrode active material (JP-A-61-161673), triethylenephosphoramide (JP-A-61-208758), trialkylphosphine (JP-A-62-80976). No.), morpholine (JP-A-62-80977),
Aryl compounds having a carbonyl group (JP-A-62-86)
No. 673), crown ethers such as 12-crown 4 (Physical Review)
B, 42, 6424 (1990)), hexamethylphosphoric triamide and 4-alkylmorpholine (JP-A-62-217575), and bicyclic tertiary amine (JP-A-62-217578). Gazette), oil (JP-A-62-287580), quaternary phosphonium salt (JP-A-63-1212268), tertiary sulfonium salt (JP-A-63-1212269), and the like. .

Further, in order to make the electrolytic solution nonflammable, a halogen-containing solvent, for example, carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolytic solution (JP-A-48-36,6).
32). Further, the electrolytic solution may contain carbon dioxide gas in order to have suitability for high temperature storage (JP-A-59-13).
4567).

The mixture for the positive electrode and the negative electrode may contain an electrolytic solution or an electrolyte. For example, the ion conductive polymer and nitromethane (Japanese Patent Laid-Open No. 48-3663).
3) and an electrolytic solution (JP-A-57-124870).

Further, the surface of the positive electrode active material can be modified. For example, the surface of a metal oxide is treated with an esterifying agent (JP-A-55-163779) or a chelating agent (JP-A-55-163780), a conductive polymer (special Examples of the treatment include treatments with JP-A-58-163188, JP-A-59-14274), polyethylene oxide and the like (JP-A-60-97561). Also, the surface of the negative electrode active material can be modified. For example, an ion conductive polymer or polyacetylene layer is provided (JP-A-58-111276), or LiCl (JP-A-58-142771).
Processing).

The collector of the electrode active material may be any electron conductor as long as it does not undergo a chemical change in the constructed battery. For example, for the positive electrode, in addition to stainless steel, nickel, aluminum, titanium, calcined carbon, etc. as the material, carbon on the surface of aluminum or stainless steel,
Those treated with nickel, titanium or silver, and the negative electrode are made of stainless steel, nickel, copper, titanium,
In addition to aluminum and calcined carbon, copper, stainless steel whose surface is treated with carbon, nickel, titanium, or silver), an Al-Cd alloy, or the like is used. It is also used to oxidize the surface of these materials. The shape is
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 is 1 to 5
Those having a diameter of 00 μm are used.

The shape of the battery can be any of coins, buttons, sheets, cylinders, 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 active material is used by being compressed into a pellet shape. The thickness and diameter of the pellet are determined by the size of the battery. Further, 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 active material is applied (coated) on the current collector, dried and compressed, and is mainly used. As a coating method, a general method can be used. Examples thereof include a reverse roll method, a direct roll method, a blade method, a knife method, an extrusion method, a curtain method, a gravure method, a bar method, a dip method and a squeeze method. The blade method, knife method and extrusion method are preferred. The coating is preferably carried out at a speed of 0.1 to 100 m / min. At this time, a good surface condition of the coating layer can be obtained by selecting the above-mentioned coating method according to the solution physical properties and drying properties of the mixture. The thickness, length and width of the coating layer are determined by the size of the battery, but the thickness of the coating layer is particularly preferably 1 to 2000 μm in a 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 mixture sheet is rolled or folded and inserted into a can, the can and the sheet are electrically connected, an electrolytic solution is injected, and a sealing plate is used to form a battery can. At this time, the safety valve can be used as a sealing plate. Other than 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, a method of making a notch in the battery can, a method of cracking a gasket, or a method of cracking a sealing plate can be used as a measure for increasing the internal pressure of the battery can. Further, the charger may be provided with a circuit incorporating measures against overcharge and overdischarge. For the can and the lead plate, a metal or alloy having electrical conductivity can be used. For example, metals such as iron, nickel, titanium, chromium, molybdenum, copper and aluminum or alloys thereof are used. As a method for welding the cap, the can, the sheet, and the lead plate, a known method (eg, DC or AC electric welding, laser welding, ultrasonic welding) can be used. As the sealing agent for sealing, a conventionally known compound or mixture such as asphalt can be used.

[0061]

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.

Example 1 The lithium-containing transition metal oxide negative electrode active materials (a) to (c) of the present invention were synthesized by using the following raw materials and firing conditions. (A) Li ₂ CO ₃ , CoO and V ₂ O ₅ were mixed and fired in air at 750 ° C. for 18 hours. (B) CoO and V ₂ O ₅ are mixed, and the temperature is 800 ° C. in air.
After calcination for 12 hours, Li ₂ CO ₃ and V ₂ O ₅ were further added to this calcination product and mixed, and calcination was performed in air at 650 ° C. for 10 hours. (C) Li ₂ CO ₃ , NH ₄ VO ₃ and NiCO ₃ · 2
_{Ni (OH) 2 · 4H 2} O were mixed, and calcined for 6 hours at 800 ° C. in air.

86 parts by weight of the above negative electrode active material, 3 parts by weight of acetylene black as a conductive agent and 6 parts by weight of graphite were mixed, and a styrene-butadiene copolymer (weight ratio = 1/1) was further used as a binder. 4 parts by weight and 1 part by weight of carboxymethyl cellulose were added and kneaded with water as a medium to obtain a slurry. The slurry was applied onto both sides of a copper foil having a thickness of 18 μm using a doctor blade coater, dried and then compression-molded with a calendar press machine to prepare a strip-shaped negative electrode sheet (3). The thickness of the negative electrode sheet after compression molding was 124 μm.

87 parts by weight of LiCoO ₂ as a positive electrode active material and 9 parts by weight of graphite as a conductive agent were mixed, and polytetrafluoroethylene 3 as a binder was added.
20 parts by weight of a slurry obtained by adding 1 part by weight of sodium polyacrylate and kneading with water as a medium.
Of aluminum foil (support) on both sides of the current collector.
The coated material was dried and compression-molded with a calendar press to prepare a strip-shaped positive electrode sheet (5) (220 μm). After spot-welding a lead plate to each end of the negative electrode sheet (3) and the positive electrode sheet (5), dew point -4
It heat-processed at 200 degreeC in dry air below 0 degreeC for 2 hours.
Further, the heat-treated positive electrode sheet (5), a microporous polypropylene film separator (Celguard 240
0) (4), the heat-treated negative electrode sheet (3) and the separator (4) were laminated in this order, and this was spirally wound.

The wound body was housed in a nickel-plated iron bottomed cylindrical battery can (2) which also served as a negative electrode terminal. Furthermore, 1 mol / liter LiP as an electrolytic solution
F ₆ (equal volume mixture of ethylene carbonate, butylene carbonate and diethyl carbonate) was injected into the battery can. A battery lid (8) having a positive electrode terminal was caulked via a gasket (1) to produce a cylindrical battery. In addition,
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 (3) by a lead terminal in advance. FIG. 1 shows a cross section of the cylindrical battery. In addition, 7 is a safety valve.

With respect to the prepared battery, the cut-off voltage of charge is 3.
Current density of 2 at 9 to 4.3 V and discharge end voltage of 1.8 V
A charge / discharge cycle test was performed at mA / cm ² . The number of cycles until the discharge capacity reached 60% of the initial value was defined as the charge / discharge cycle life. In the first embodiment of the present invention, the value of 0.
After discharging to 5 to 1.5 V, charging was performed. In the comparative example, the discharge before charging was not performed, or the discharge end voltage was set lower than 0.5V or higher than 1.5V. The results are shown in Table 1.

[0067]

[Table 1]

Example 2 A cylinder battery was prepared in exactly the same manner as in Example 1.
Regarding the created battery, the final charge voltage is 3.9 to 4.3.
V, discharge end voltage 0.5-1.5V, current density 2m
A charge / discharge cycle test was performed at A / cm ² . The results are shown in Table 2.
It was shown to.

[0069]

[Table 2]

Example 3 As shown in Table 3, (d) LiNiO ₂ and (e) LiCo _0.5 Ni _0.5 were used instead of LiCoO ₂ as the positive electrode active material.
O ₂ , (f) LiCo _0.95 V _0.05 O _2.05 , (g) LiMn ₂
A cylinder battery was prepared in exactly the same manner as in Example 1 except that O ₄ was used. A charge / discharge cycle test was performed on the prepared battery in the same manner as in Example 1. The results are shown in Table 3.

[0071]

[Table 3]

As is clear from a comparison between the present invention of Examples 1 to 3 and the comparative example, the charging / discharging method of the present invention in which charging is performed after discharging to 0.5 to 1.5 V in the charging / discharging cycle. It was shown that the battery using C. had longer charge / discharge cycle life than the comparative example.

[0073]

The negative electrode active material is Lix MOj (provided that M
Is Ti, V, Mn, Co, Fe, Ni, Nb and Mo
Represents at least one transition metal selected from, x is in the range of 0.17 to 11.25, and j is 1.6
In the range of 4.1 to 4.1), wherein the positive electrode active material is Li _y NO _z (wherein N represents at least one transition metal and at least one of the transition metals is Co, Mn, Ni, V and Fe
Which represents at least one transition metal selected from y, y is in the range of 0.2 to 1.2, and z is in the range of 1.4 to 3).
In a non-aqueous secondary battery with the end-of-charge voltage set to 3.5 to 4.7 V, a large charge / discharge capacity and a long charge capacity are obtained by charging after discharging to 0.5 to 1.5 V in a charge / discharge cycle. A non-aqueous secondary battery having a discharge cycle life can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a cylinder battery used in Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polypropylene insulation sealing body 2 Negative electrode can (battery can) also serving as a negative electrode terminal 3 Negative electrode sheet 4 Separator 5 Positive electrode sheet 6 Liquid non-aqueous electrolyte 7 Flexible thin plate valve body 8 Positive electrode cap also serving as positive electrode terminal 9 PTC element 10 Sealing plate 11 Ring

Claims (9)

[Claims] 1. A non-aqueous secondary battery comprising a positive electrode active material, a negative electrode active material, and a non-aqueous electrolyte containing a lithium salt, wherein the negative electrode active material is Lix MOj (where M is Ti,
Represents at least one transition metal selected from V, Mn, Co, Fe, Ni, Nb, and Mo, and x is 0.17 to
A lithium-containing transition metal oxide represented by the formula 11.25 and j in the range 1.6 to 4.1), wherein the positive electrode active material is Li _y NO _z (where N is Represents at least one transition metal, and at least one of the transition metals represents at least one transition metal selected from Co, Mn, Ni, V, and Fe, and y is 0.2 to 1.
In the range of 2 and z is in the range of 1.4 to 3), the non-aqueous secondary battery is a lithium-containing transition metal oxide represented by And a charging / discharging method for a non-aqueous secondary battery, which comprises charging after discharging to 0.5 to 1.5 V in a charging / discharging cycle. 2. The range of discharge end voltage used is 1.5 V.
The charging / discharging method of the non-aqueous secondary battery according to claim 1, wherein the charging voltage is 3.0 V or less. 3. The range of discharge end voltage used is 0.5 V.
The charging / discharging method of the non-aqueous secondary battery according to claim 1, wherein the charging voltage is less than 1.5 V. 4. The transition metal oxide, wherein the negative electrode active material is a transition metal oxide in which the basic structure of the crystal is changed by inserting lithium ions, and the basic structure of the crystal after the change is in a state where the basic structure of the crystal does not change due to charge and discharge. The charging / discharging method of the non-aqueous secondary battery according to claim 1. 5. The transition metal oxide before insertion of lithium ions is Lip MOj (where M is Ti, V, Mn, C).
represents at least one transition metal selected from o, Fe, Ni, Cr, Nb and Mo, p is in the range of 0 to 3.1, and j is in the range of 1.6 to 4.1). The non-aqueous secondary battery according to claim 1, comprising the transition metal oxide represented. 6. The non-aqueous secondary battery according to claim 1, wherein the negative electrode active material is an oxide of a transition metal into which lithium ions are electrochemically inserted. 7. The non-aqueous secondary battery according to claim 1, wherein the negative electrode active material is obtained by further inserting lithium ions into a lithium-containing transition metal oxide produced by firing. Charge / discharge method. 8. The negative electrode active material is Lix Mq V ₁ -q Oj
(However, M represents a transition metal, p is in the range of 0 to 3.1, x is in the range of 0.17 to 11.25, q is in the range of 0 to 0.7, and j is Is in the range of 1.3 to 4.1). The charge / discharge method for a non-aqueous secondary battery according to claim 1, comprising a lithium-containing transition metal oxide represented by the formula: 9. The positive electrode active material is Li_yCoO₂, Li
_yNiO₂, Li_yCo_aNi_1-aO₂, Li_yCo_b
V_1-bO₂, Li_yCo_bFe_1-bO₂, Li_yMn₂
O_Four, Li_yMn_cCo_2-cO_Four, Li_yMn_cNi
_2-cO_Four, Li _yMn_cV_2-cO_FourAnd Li_yMn_cF
e_2-cO_Four(However, y is in the range of 0.5 to 1.2,
a is in the range of 0.1 to 0.9, b is 0.8 to 0.9
8, c is in the range of 1.6 to 1.96,
z is in the range of 2.01 to 2.3)
The non-aqueous electrolyte according to claim 1, wherein the non-aqueous electrolyte comprises a transition-metal-containing oxide.
How to charge and discharge the next battery.