JPH1064520A - Lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lithium ion type nonaqueous electrolyte secondary battery improving a cycle life, increasing a discharge capacity, reducing a cost and enhancing safety. SOLUTION: This battery comprises a positive electrode active material mainly composed of a lithium manganese compound oxide, represented by a composition range of LiMna Ma/c O4+b (M is metal cation except Li, 0<y<=1.2, 0<=a<=0.2, 1<=c<=3, 0<=b<0.3), negative electrode active material mainly composed of tin oxide and a nonaqueous electrolyte. Here, the positive electrode active material is 0.05μm or more 1.0μm or less in the average grain size of primary grain and 2μm or more 25μm or less in the average grain size of secondary grain.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium ion non-aqueous electrolyte secondary battery having excellent charge-discharge cycle life, improved storage stability and safety.

[0002]

2. Description of the Related Art As a positive electrode active material useful for a high energy type lithium ion secondary battery having a voltage of 4V class, there are LiMn ₂ O ₄ having a spinel structure and LiMn having a rock salt structure.
O ₂ , LiCoO ₂ , LiCo _1-x Ni _x O ₂ , LiN
iO _{2 and the} like are generally used. Above all, JP 55
LiCoO _{2 of the} rock salt structure type disclosed in US Pat.
Is advantageous in that it has a high voltage and a high capacity, but it has a problem of high production cost due to a small supply amount of the cobalt raw material and a problem of environmental safety of a waste battery. Thus, a spinel structure type Li _x Mn ₂ O ₄ made from manganese, which has a large supply amount and is low in cost and has good environmental suitability, is used.
The structure of a secondary battery using as a positive electrode material is disclosed in JP-A-3-14.
7276, 4-123769, and the like. Japanese Patent Application Laid-Open No. Hei 5-13107 discloses a method in which a manganese oxide is mixed with a cobalt oxide and used as a positive electrode. However, LiMn ₂ O ₄ has a charge capacity per volume (that is, Li release amount) of 10 to 20 compared to LiCoO _2.
Therefore, when combined with a negative electrode active material having a high capacity, the use volume of the positive electrode active material increases, and the amount of the negative electrode active material used is limited. As a result, the battery capacity decreases. Another problem is that LiMn ₂ O ₄ contains C
Li release rate during charging compared to o-oxide (95% when fully charged)
% Or more) often causes problems such as poor storage stability and poor charge / discharge cycle life. As an improvement method, for example, JP-A-4-141954 and JP-A-4-16076
9, 4-345759, 5-036412, 5-
As shown in 283075, a second manganese oxide
Means for strengthening the structure by mixing the above metal elements can be considered. However, in these methods, depending on the mixing ratio of the second metal, as a result of reducing the Mn content in the crystal, the capacity is significantly reduced.

[0003]

A first object of the present invention is to provide a secondary battery using a high-voltage lithium manganese oxide as a positive electrode active material and a high-capacity metal oxide active material as a negative electrode active material. The second problem is to provide a secondary battery which is excellent in storage stability and safety, and the third problem is to provide excellent cost performance. It is to provide a secondary battery.

[0004]

SUMMARY OF THE INVENTION The above-mentioned problem is solved by Li _y M
n _2-a Ma _{/ c} O _{4 + b} (M is a metal cation other than Li;
<Y ≦ 1.2, 0 ≦ a ≦ 0.2, 1 ≦ c ≦ 3, 0 ≦ b <
0.3) A positive electrode active material mainly composed of a lithium manganese composite oxide, a negative electrode active material mainly composed of tin oxide, and a non-aqueous electrolyte represented by a composition range of 0.3).
0.05 μm or more and 1.0 μm in average particle diameter of the secondary particles
Or less, and the average particle size of the secondary particles is 2 μm or more and 2
In a lithium ion secondary battery or a similar configuration, the positive electrode active material is 0.1 μm or more and 0.5 μm or less in the average particle size of the primary particles and the average particle size of the secondary particles is 5 μm or less. The problem has been solved by using a lithium ion secondary battery having a size of 2 μm or more and 25 μm or less.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below, but the present invention is not limited thereto. Composition formula Li _y Mn _2-a Ma _{/ c} O _{4 + b} (M is a metal cation other than Li, 0 <y ≦ 1.2, 0 ≦ a ≦ 0.2, 1 ≦
c ≦ 3, 0 ≦ b <0.3), comprising a positive electrode active material mainly composed of a lithium manganese composite oxide, a negative electrode active material mainly composed of tin oxide, and a non-aqueous electrolyte. The average particle size of the primary particles of the oxide is 0.0
A lithium ion secondary battery having a size of 5 μm or more and 1.0 μm or less and an average particle size of secondary particles of 2 μm or more and 25 μm or less. Item 1. The average particle diameter of primary particles of the lithium manganese composite oxide is 0.1 μm or more and 0.5 μm or less, and the average particle diameter of secondary particles is 2 μm or more and 25 μm or less. Lithium ion secondary battery. Li _y Mn _2-a Ma _{/ c} O _{4 + b} (M is a metal cation other than Li, 0 <y ≦ 1.2, 0 ≦ a ≦ 0.2, 1 ≦ c ≦
3,0 ≦ b <0.3) composed of a positive electrode active material mainly composed of a lithium manganese composite oxide, a negative electrode active material mainly composed of tin oxide, and a non-aqueous electrolyte represented by a composition range of:
A lithium ion secondary battery characterized in that the specific surface area of the lithium manganese composite oxide particles measured by a BET method is in the range of 1.0 to 8.0 m ² / g. 4. The lithium ion secondary battery according to any one of items 1 to 3, wherein the specific surface area of the lithium manganese composite oxide particles measured by the BET method is in the range of 1.5 to 5.0 m ² / g. Next battery. In the charge / discharge cycle of the secondary battery, y, a, c, and b of the lithium manganese composite oxide represented by the composition formula Li _y Mn _2-a Ma _{/ c} O _{4 + b} (M is a metal cation other than Li) are used. , 0 <y ≦ 1.2, 0 ≦ a ≦ 0.2, 1 ≦ c ≦ 3, 0
The lithium-on secondary battery according to any one of Items 1 to 4, wherein the range of ≦ b <0.3 is satisfied. Compositional formula Li _y Mn _2-a Ma _{/ c} O _{4 + b} (0 <y ≦ 1.
2, 1 ≦ c ≦ 3, 0 ≦ b <0.3), the range of “a” is 0 <a ≦ 0.2, and M is Co, Ni, Fe, Cr, Cu Item 6. The lithium ion secondary battery according to any one of Items 1 to 5, which is one or more transition metal element cations selected from Ti. Negative electrode active material is a composite oxide of amorphous containing as a main component of tin, formula SNM _x O _z or _{Sn y T 1-y M x} O
_z (M is Al, B, P, Si, Ge, Group 1 of the periodic table,
Indicate at least one element selected from Group II, III, and halogen elements; 0.2 ≦ x2, 0.1 ≦ y ≦ 0.9, 1 ≦
7. The lithium ion secondary battery according to any one of items 1 to 6, wherein z ≦ 6, T represents a transition metal). Composition formula Li _y Mn _2-a Ma _{/ c} O _{4 + b} (M is a metal cation other than Li, 0 <y ≦ 1.2, 0 ≦ a ≦ 0.2, 1 ≦
c ≦ 3, 0 ≦ b <0.3), a composition formula Li _{1 + X} Mn _2-a M _{a / c} synthesized by insertion of lithium ions in a sealed battery O
_{4 + b} (0.3 <x <1.2, M is one or more metal cations except Li, 0 ≦ a ≦ 0.2, c is a value depending on the oxidation number of M, and 1 ≦ c ≦ The lithium secondary battery according to any one of Items 1 to 7, which is prepared by a method of activating a battery precursor containing a precursor of (3, 0 ≦ b <0.3) by charging. battery. Hereinafter, the present invention will be described in detail. The secondary battery of the present invention uses a positive electrode active material mainly composed of a lithium manganese composite oxide. In the present invention, the positive electrode active material may be the lithium manganese composite oxide itself described in detail below, or another oxide may be used in combination. What is preferably used as the lithium-manganese composite oxide of the present invention is a spinel-type manganese-containing oxide that gives a high voltage. The spinel-type oxide has a structure represented by the general formula A (B ₂ ) O ₄ , wherein oxygen anions are arranged in a cubic close-packed form, and a part of tetrahedral and octahedral faces and vertices is provided. Occupy. Depending on the distribution state of the cation A, A (B ₂ ) O ₄ is called a normal spinel and B (A, B) O ₄ is called an inverse spinel.
Impinges on these intermediate states, A _x B _y (A
Structure of _{1-x B 1-y)} O 4 is also present as a spinel. As a typical manganese oxide having a normal spinel structure, L
iMn ₂ O ₄ is mentioned. In this structure, half of the Mn cation is trivalent and half is tetravalent, and the average number of charges is given by 3.5. Λ, also known as active material
-MnO ₂ is a defective spinel structure in the form of LiMn ₂ O ₄ with lithium removed, as shown in US Pat. No. 4,246,253, in which MnO ₂
All cations are tetravalent. The manganese oxide cathode active material used in the present invention includes a normal spinel type, a reverse spinel type, and a defect-free spinel structure or a defect non-stoichiometric spinel structure. When the positive electrode carrying the manganese oxide is positively polarized and electrochemically charged, Li in the active material is released as cations and the positive electrode potential increases, and the average charge of manganese in the active material is Increase toward 4.0. In a high-charge state where the average charge is close to 4.0, disproportionation of manganese ions progresses and a part of the manganese ions is eluted as divalent cations into the electrolyte, which causes deterioration of reversibility of charge and discharge. . As one method of suppressing the disproportionation reaction and improving the cycle life of the battery, in the present invention, as described later, a small amount of another metal cation (M) is added to manganese in the crystal structure. A positive electrode active material is prepared.

In the present invention, as a preferable method for increasing the capacity, a low-voltage (open electromotive voltage of 1 V or less) battery precursor containing a manganese composite oxide as a cathode active material precursor is electrochemically activated. A high-voltage secondary battery is manufactured by a method of converting a positive electrode active material precursor into a positive electrode active material having a different crystal structure and a higher potential. Here, both the positive electrode active material precursor and the one preferably used as the positive electrode active material are lithium-containing manganese composite oxides having a spinel-type crystal structure. The tertiary arrangement of the crystal lattice is different. That is, in the active material of the present invention having a basic structure of LiMn ₂ O ₄ , the precursor is Li _{1 + X} Mn ₂
It is a tetragonal crystal having a basic composition of O ₄ (0 <x <1.2), and the active material is Li _y Mn ₂ O ₄ (0 <y ≦ 1.
It is a cubic crystal having the basic composition of 2). As a result, the potential levels of both of them relating to the release and occlusion of Li are greatly different. The potential levels are close to 3 V vs. Li for the precursor and close to 4 V for the active material, with a 1 V difference.
In the present invention, since a 4V-class output voltage is applied to the secondary battery, a cubic structure having a basic composition of Li _y Mn ₂ O ₄ (0 <y ≦ 1.2) is changed to a cubic structure during charge and discharge. Used as a positive electrode active material. More specifically, preferred embodiments of the present invention will be described. In order to prepare the positive electrode active material, Li _{1 + x} Mn _2-a Ma _{/ c} O, which is a precursor of the positive electrode active material, is used.
_{4 + b} (0.3 <x <1.2, one or more metal cations except Li, 0 ≦ a ≦ 0.2, c is a value depending on the oxidation number of M, and 1 ≦ c ≦ 3 First, a stoichiometric or non-stoichiometric spinel-type manganese composite oxide represented by a composition of 0 ≦ b <0.3) is synthesized, and a battery precursor containing this cathode precursor is subjected to a charging operation. By activating, a secondary battery including the positive electrode active material of the present invention is completed. The synthesis of the positive electrode precursor is performed by electrochemical lithium insertion into the manganese oxide, preferably inside the battery, as described below. In the composition of the precursor and the active material, M is a doping element for Mn, preferably a trivalent to tetravalent transition metal element, and more preferably Co, Ni, Fe, C
It is a transition metal element selected from r, Cu, and Ti. The value of a / c, which is the doping ratio of M to Mn, is a value dependent on the oxidation number of M. Preferably, the oxidation number of Mn is 3.5 to 3.5 at the stage when the positive electrode active material is involved in the charge / discharge cycle. It is a value that takes a range of 4.0. In addition, the dough of M
In order not to reduce the capacity of the active material, it is preferable that the content of M is lower than that of Mn, and the value of a is 0 ≦ a ≦ 0.
The range of 2 is preferable, and the range of 0 <a ≦ 0.10. Other elements preferably used as M for improving storage stability are Zr, Nb, and Y. Also, M
For the same reason, lanthanide elements represented by La, Sm, Eu and the like are also preferable. Further, in order to improve cycle life and storage stability, M is Na, K, Ca, M
It is also effective to add a small amount of an alkali cation such as g to Li. The positive electrode active material precursor is added to the positive electrode composition composed of manganese oxide inside the sealed battery according to the method described in Examples, etc.
It is synthesized by electrolytically inserting Li from the raw material into the positive electrode. At this time, a preferable level for inserting Li is such that x is in the range of 0.5 <x <1.2 in the composition of Li _{1 + x} Mn _2-a Ma _{/ c} O ₄ . This is because if x exceeds 1.2, the structure of the precursor becomes unstable in terms of reversibility of Li release. The positive electrode active material precursor is activated by releasing lithium ions from the precursor composition by precharging the battery precursor. By this activation operation, Li _y Mn _2-a before the start of charge / discharge (that is, before use in the charge / discharge cycle) and during the charge / discharge cycle.
It is converted into a high potential type positive electrode active material that maintains the composition range of Ma _{/ c} O ₄ (0 <y ≦ 1, 0 ≦ a <0.2). In the present invention, the positive electrode active material means the state of the positive electrode material immediately before completion of the battery and before use in the charge / discharge cycle, and the state of the positive electrode material being used in the charge / discharge cycle.

For the lithium-containing manganese oxide as the positive electrode active material of the present invention, particles having a specific morphology are used for the purpose of improving the reversibility of the charge / discharge cycle and the life. The particles of the positive electrode active material are composed of fine particles (herein referred to as primary particles), and a part thereof aggregates to form relatively large particles (herein referred to as secondary particles). The average particle diameter of the primary particles is 0.05 in the median diameter measured by a laser-type particle size distribution measuring method utilizing laser light diffraction.
μm or more and 1.0 μm or less, preferably 0.1 μm
The size is not less than 0.5 μm. The average particle size of the secondary particles is 2 μm or more and 25 μm or less, preferably 2 μm or more and 20 μm or less in median diameter. Also,
The average particle size of the secondary particles is more preferably 5 μm or more and 20 or more.
μm or less. In the particle size measurement, when the active material particles are subjected to laser type particle size distribution measurement, peaks or plates of two distributions derived from the primary particles and the secondary particles appear, so that the primary particles are formed. And the state of a particle group including two types of secondary particles. The average particle size of the secondary particles can be read directly from this distribution diagram including the two types.
On the other hand, the average particle size of the primary particles is
The particle size of 5 μm or more is removed, and the particle size distribution of the remaining particles is determined by a laser type particle size distribution measuring method or an electron microscope observation method. In many cases, it can also be predicted from the fact that the particle size of the primary particles substantially matches the particle size of the manganese oxide (such as manganese dioxide) used in the synthesis raw material.

[0008] The positive electrode active material of the present invention is characterized in that the particle surface area does not exceed a specific value for the purpose of suppressing deterioration of the charge / discharge cycle life due to irreversible reaction with an electrolyte. The particle surface area needs to be in the range of 1.5 to 8.0 m ² / g in room temperature measurement by the BET method,
It is preferably in the range of 1.5 to 4.0 m ² / g.

The cathode active material of the present invention can be obtained by reacting a lithium salt with a manganese salt or manganese oxide at a high temperature in a solid phase. When lithium carbonate and manganese dioxide are used as the raw materials, the firing temperature is 350 ° C to 800 ° C, preferably 350 ° C to 700 ° C, and the firing time is 8 hours to 48 hours. When lithium hydroxide and manganese dioxide are used as raw materials, the firing temperature is from 350 ° C. to 800 ° C.
° C, preferably from 400 ° C to 750 ° C, and the calcination time is from 8 hours to 48 hours. When low-melting lithium nitrate (melting point: 261 ° C.) is used as the lithium salt, the firing temperature is from 300 ° C. to 800 ° C., preferably 30 ° C.
0 ° C to 500 ° C. As a manganese oxide, λ
-MnO _2, electrolytically prepared MnO ₂ (EMD),
Chemically prepared MnO ₂ (CMD) and mixtures thereof can be used. Other lithium materials include lithium-manganese composite oxides (eg, Li ₂ M
n ₄ O ₉ ) can be used. In this case, the lithium-manganese composite oxide is mixed with a manganese raw material such as manganese dioxide and calcined at 350 to 500 ° C.

In the positive electrode of the present invention, in addition to the above compounds as a manganese composite oxide, LiMnO ₂ having a rock salt structure,
And Li _{1 + x} formed by insertion of Li into LiMn ₂ O ₄
Mn ₂ O ₄ (0 ≦ x ≦ 0.5) or LiMn ₂ O ₄
Li _1-x Mn ₂ O ₄ (0 ≦
x ≦ 0.5) may also be added.

In the positive electrode active material, another transition metal composite oxide can be mixed with lithium manganese oxide as a secondary active material. Preferred as the secondary active material to be mixed is also a high-capacity high-voltage lithium-cobalt composite oxide, Li
x CoO ₂ (0.5 <x ≦ 1). In addition, lithium cobalt nickel composite oxide, Li _x Co _y Ni _z O ₂
(0.5 <x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ z ≦ 1) is also preferable. In addition to LiCoO ₂ , a solid solution to which various transition metals, non-transition metals, alkali elements, rare earth elements, and the like are added in addition to Co can also be used as a sub-active material. The preferable mixing ratio of the sub-active material in the active material mixture is, for example, when lithium cobalt oxide is used as the sub-active material, the weight ratio of lithium cobalt oxide to lithium manganese oxide is in the range of 2/8 to 9/1. Yes, it is more preferably in the range of 3/7 to 7/3.

The negative electrode active material used in the negative electrode of the present invention comprises:
Li-insertable composite oxide mainly composed of tin oxide, which activates a negative electrode active material precursor substantially free of Li by inserting Li in advance in a battery and converts it into a low-potential active material. Obtained by the method. Preferred as a precursor of the negative electrode active material is a composite oxide containing tin. The composite oxide containing tin is preferably amorphous, and is preferably represented by the following general formula (1) or (2). (1) SnM _x O _z (2) Sn _y T _{1 -y} M _x O _z where M is Al, B, P, Si, Ge, periodic table first
Represents at least one element selected from the group consisting of Group 2, Group 3, Group 3 and halogen elements, and 0.2 ≦ x2, 1 ≦ z ≦ 6, 0.1 ≦
y ≦ 0.9, T represents a transition metal, preferably V, T
i, Fe, Mn, Co, Ni, Zn, W, and Mo.
Preferred in the general formula (1) is that M is Al, B,
P, Ge, and two or more elements selected from Group 1, Group 2, Group 3, and halogen elements of the periodic table, and 0.2 ≦ x
2,1 ≦ z ≦ 6,0, and particularly preferred is a precursor represented by the general formula (3). (3) SnM _a M ¹ b O _z where M is at least one of Al, B, and P, and M ¹ is 1 selected from the first, second, third, and third groups of the periodic table. More than one kind of element, 0.2 ≦ a ≦ 2,0.0
1 ≦ b ≦ 1, 0.2 ≦ a + b ≦ 2, 1 ≦ z ≦ 6.

It is preferable that the negative electrode active material precursor is mainly amorphous when incorporated into a battery. The term “amorphous” used herein means 20 ° in 2θ value by X-ray diffraction using CuKα ray.
It is a substance that gives a broad scattering band having an apex at an angle of 40 ° from the surface, and may have a crystalline diffraction line in the scattering band.
Preferably, the strongest intensity among the crystalline diffraction lines observed at 40 ° or more and 70 ° or less in 2θ value is 20 ° in 2θ value.
The intensity is preferably 500 times or less, more preferably 100 times or less, particularly preferably 5 times or less, the intensity of the diffraction line at the apex of the broad scattering band observed at 40 ° or more.
Most preferably, it has no crystalline diffraction line.

Examples of the precursor of the negative electrode active material used in the present invention are shown below. SnSi _0.8 P _0.2 O _3.1 , SnSi _0.5
Al _0.1 B _0.2 P _0.2 O _1.95 , SnSi _0.8 B _0.2 O
_2.9 , SnSi _0.8 Al _0.2 O _2.9 , SnSi _0.6 Al
_0.1 B _0.2 O _1.65 , SnSi _0.3 Al _0.1 P
_0.6 O _2.25 , SnSi _0.4 B _0.2 P _0.4 O _2.1 , SnS
i _0.6 Al _0.1 B _0.5 O _2.1 , SnB _0.5 P _0.5 O ₃ ,
SnAl _0.3 B _0.5 P _0.2 O _2.7 , SnK _0.2 P
O _3.6 , SnRb _0.2 Al _0.05 P _0.8 O _3.25 SnAl
_0.3 B _0.7 O _2.5 , SnBa _0.1 Al _0.15 P
_1.45 O _4.7 , SnLa _0.1 Al _0.1 P _0.9 O _3.55 , Sn
Na _0.1 Al _0.05 B _0.45 O _1.8 , SnLi _0.2 B _0.5 P
_0.5 O _3.1 , SnCs _0.1 B _0.4 P _0.4 O _2.65 , SnB
a _0.1 B _0.4 P _0.4 O _2.7 , SnCa _0.1 Al _0.15 B
_0.45 P _0.55 O _3.9 , SnY _0.1 Al _0.3 B _0.6 P _0.6 O
₄ , SnRb _0.2 Al _0.1 B _0.3 P _0.4 O _2.7 , SnC
s _0.2 Al _0.1 B _0.3 P _0.4 O _2.7 SnCs _0.1 Al
_0.1 B _0.4 P _0.4 O _2.8 , SnK _0.1 Cs _0.1 B _0.4 P
_0.4 O _2.7 , SnBa _0.1 Cs _0.1 B _0.4 P
_0.4 O _2.75 , SnMg _0.1 K _0.1 B _0.4 P _0.4 O _2.75 ,
SnCa _0.1 K _0.1 B _0.4 P _0.5 O ₃ , SnBa _0.1 K
_0.1 Al _0.1 B _0.3 P _0.4 O _2.75 , SnMg _0.1 Cs
_0.1 Al _0.1 B _0.3 P _0.4 O _2.75 , SnCa _0.1 K _0.1
Al _0.1 B _0.3 P _0.4 O _2.75 , SnMg _0.1 Rb _0.1 A
l _0.1 B _0.3 P _0.4 O _2.75 , SnCa _0.1 B _0.2 P _{0.2
F 0.2 O 2. 6, SnMg 0.1} Cs 0.1 B 0.4 P 0.4 F
_0.2 O _3.3 , SnMg _0.1 Al _0.2 B _0.4 P _0.4 F _0.2
O _2.9 , Sn _0.5 Mn _0.5 Mg _0.1 B _0.9 O _2.45 , Sn
_0.5 Mn _0.5 Ca _0.1 P _0.9 O _3.35 , Sn _0.5 Ge _0.5
Mg _0.1 P _0.9 O _3.35 , Sn _0.5 Fe _0.5 Ba _0.1 P
_0.9 O _3.35 , Sn _0.5 Fe _0.5 Al _0.1 B _0.9 O _2.5 ,
Sn _0.8 Fe _0.2 Ca _0.1 P _0.9 O _3.35 , Sn _0.3 Fe
_0.7 Ba _0.1 P _0.9 O _3.35 Sn _0.9 Mn _0.1 Mg _0.1 P
_0.9 O _3.35 , Sn _0.2 Mn _0.8 Mg _0.1 P _0.9 O _3.35 ,
Sn _0.7 Pb _0.3 Ca _0.1 P _0.9 O _3.35 , Sn _0.2 Ge
_0.8 Ba _0.1 P _0.9 O _3.35 , Sn _1.0 Al _0.1 B _0.5 P
_0.5 O _3.15 , Sn _1.0 Cs _0.1 B _0.5 P _0.5 O _3.05 , S
n _1.0 Cs _0.1 Al _0.1 B _0.5 P _0.5 O _3.20 , Sn _1.0
Cs _0.1 Al _0.3 B _0.5 P _0.5 O _3.50 , Sn _1.0 Cs
_0.1 Ge _0.05 Al _0.1 B _0.5 P _0.5 O _3.30 , Sn _1.0 C
s _0.1 Ge _0.05 Al _0.3 B _0.5 P _0.5 O _3.60 .

The negative electrode active material used in the present invention can be obtained by electrochemically or chemically preliminarily inserting lithium ions into the above-mentioned negative electrode active material precursor. In the method of electrochemically inserting lithium ions, the negative electrode is cathode-polarized and charged in a battery made of a nonaqueous electrolyte containing a lithium salt, using the precursor of the positive electrode active material of the present invention as a counter electrode. This is performed by inserting lithium ions, or by direct self-discharge reaction from lithium metal or lithium alloy supported on the negative electrode. The amount of Li inserted into the negative electrode active material precursor is not particularly limited, but may be, for example, 0.05 to 0.05% by weight of Li-Al (80 to 20% by weight).
It is preferable to insert until V is reached. 0.1V
It is preferable to insert up to 0.15V. At this time, since the equivalent of the preliminary insertion of lithium depends on the potential and is 3 to 10 equivalents, the capacity of the preliminary insertion is usually a high value of 500 mAh / g. In correspondence with this capacity, the positive electrode active material precursor and Li
(Or Li alloy) is determined. Specifically, it is desirable to set the total equivalent of the releasable Li contained in the positive electrode active material precursor and Li (or Li alloy) to be 0.5 to 2 times the equivalent of the above-mentioned lithium insertion.

Next, a method for preparing the positive electrode active material used in the present invention by activating the inside of the battery starting from the precursor will be described. In the present invention, activation of the positive electrode means a potential that is electrochemically noble until the active material has a crystal structure capable of reversibly charging / discharging (allowing Li release and insertion) while having a high discharge potential. Means activated. In the case of the positive electrode active material Li _y Mn _1-a Ma _{/ c} O _{4 + b} used in the charge / discharge cycle in the present invention, this sufficiently high potential means a potential of 3.8 V or more, preferably 4.2 V or more with respect to Li. At a potential of 4.2 V or more, 0.9 or more of Li in the structure of the active material is released (at 4.3 V, 0.95 or more). However, Liy <
The amount of Li released when charging is started from the structure of 1.2 Mn _1-a Ma _{/ c} O _{4 + b} (that is, charging capacity) is, for example, 1 to LiCoO ₂ when converted per active material weight.
0-20% smaller. As in the embodiment of the secondary battery of the present invention, the precharge (Li
When a metal oxide with a large capacity is used,
It is necessary to particularly increase the amount of Li released from the positive electrode. Therefore, when Li _y Mn _1-a Ma _{/ c} O _{4 + b} is used as the active material, Li _y Mn _1-a Ma _{/ c} O _{4 + b} is further added to Li _y Mn _1-a Ma _{/ c} O _{4 + b.}
Reduced Li _{1 + x} Mn _1-a M _{a / c} having the structure inserted by
It is necessary to increase the amount of Li released to the negative electrode active material precursor by using O _{4 + b} as a precursor before activation.

Li _{1 + x} Mn _1-a M of precursor before activation
_{Since a / c} O _{4 + b} is unstable on storage, in the present invention, the synthesis of this precursor is carried out inside the battery, with the manganese-containing composite oxide on the positive electrode and the Li metal supported on the positive electrode or the negative electrode. And a discharge reaction in a battery. In the process of discharging, when Li is carried on the negative electrode, the discharging is performed by discharging the battery through an external circuit. At this time, a part of the lithium on the negative electrode is contained in the negative electrode active material precursor. Inserted simultaneously by discharge. Here, the following method is used as a method of supporting Li metal on the positive electrode or the negative electrode. 1) Li or L is applied to the current collector supporting the active material precursor.
The i alloy is electrically joined. 2) A Li or Li alloy thin film is bonded to the surface of the active material precursor layer of the current collector on which the active material precursor is supported. 3) Li on the surface protection layer containing the conductive material and the like coated on the active material precursor layer of the current collector on which the active material precursor is supported
The thin films are bonded. Among the above methods, preferred methods are 2 and 3, and particularly preferred is method 3. That is, in the method 3, an abrupt reaction between the active material precursor and Li is relaxed by inserting an intermediate layer having appropriate conductivity between the active material precursor and Li, and the heat generated by the reaction is reduced. Can be suppressed. In the present invention, the composition of the lithium manganese composite oxide, which is the positive electrode active material, is required to maintain a high battery discharge voltage when the secondary battery performs the charge / discharge cycle after the activation is completed, so that Li _y Mn _1-a M _{a / c} O _{4 + b} (0 <y <1.2
), And the composition of the positive electrode active material involved in the charge / discharge cycle is Li _y Mn _1-a Ma _{/ c} O _{4 + b} (1.2 <
y). Further, a more preferable range of the composition of the positive electrode active material related to the charge / discharge cycle of the secondary battery of the present invention is Li _y Mn _1-a Ma _{/ c} O _{4 + b} , where 0 <y ≦
1, and a particularly preferable range is 0.05 <y <0.9. In the present invention, the composition of the positive electrode active material in a state before the secondary battery is used in a charge / discharge cycle (that is, after completion of activation of the positive electrode) refers to a composition of either a charged state or a discharged state of the battery. means. The charge state corresponds to the state immediately after the end of activation, in which lithium ions have been released, and the discharge state corresponds to the state in which the battery has been discharged to an appropriate battery voltage to ensure safety at the time of shipment.
In this state, lithium ions are inserted.

Preferred examples of the composition of the positive electrode active material used in the secondary battery of the present invention before use in a charge / discharge cycle (however, the discharge state) and the composition of the active material during a charge / discharge cycle are described below. Are listed. Composition number [Composition range of positive electrode active material] Before charge / discharge cycle (discharge state) When using charge / discharge cycle 1. 1. Li _0.9 Mn _2.0 O ₄ Li _0.1 to _0.9 Mn _2.0 O ₄ 2. Li _0.9 Mn _1.9 Co _0.1 O ₄ Li _0.1 to _0.9 Mn _1.9 Co _0.1 O ₄ 3. Li _0.9 Mn _1.9 Fe _0.1 O ₄ Li _0.1 to _0.9 Mn _1.9 Fe _0.1 O ₄ Li _0.9 Mn _1.9 Cr _0.05 O ₄ Li _0.1 to _0.9 Mn _1.9 Cr _0.05 O ₄ Li _0.9 Mn _1.9 Cu _0.1 O ₄ Li _0.2 to _0.9 Mn _1.9 Cu _0.1 O ₄ 6. Li _0.9 Mn _1.85 Ni _0.07 O ₄ Li _0.2 to _0.9 Mn _1.85 Ni _0.07 O ₄ 7. Li _0.9 Mn _1.95 Ti _0.05 O ₄ Li _{0.2 0.9} Mn _1.95 Ti _0.05 O ₄ 8.Li _0.9 Mn _1.95 Zr _0.05 O ₄ Li _0.2 to _0.9 Mn _1.95 Zr _0.05 O ₄ 9. Li _0.9 Mn _1.95 Nb _0.05 O ₄ Li _0.2 to _0.9 Mn _1.95 Nb _0.05 O ₄ 10. Li _0.9 Mn _1.95 Y _0.05 O ₄ Li _0.2 to _0.9 Mn _1.95 Y _0.05 O ₄ 11. Li _0.9 Mn _1.95 Al _0.05 O ₄ Li _0.2 to _0.9 Mn _1.95 Al _0.05 O ₄ 12. Li _1.0 Mn _1.97 Na _0.03 O ₄ Li _0.2 to _1.0 Mn _1.97 Na _0.03 O ₄ 13. 13. Li _1.0 Mn _1.97 Mg _0.03 O ₄ Li _0.2 to _1.0 Mn _1.97 Mg _0.03 O ₄ Li _1.0 Mn _1.97 Ca _0.03 O ₄ Li _0.2 to _1.0 Mn _1.97 Ca _0.03 O ₄ 15. Li _1.0 Mn _1.97 Cs _0.03 O ₄ Li _0.2 to _1.0 Mn _1.97 Cs _0.03 O ₄ 16. Li _1.0 Mn _1.92 La _0.04 O ₄ Li _0.2 to _1.0 Mn _1.92 La _0.04 O ₄ 17. Li _1.0 Mn _1.92 Ce _0.08 O ₄ Li _0.2 to _1.0 Mn _1.92 Ce _0.08 O ₄ 18. Li _1.0 Mn _1.92 Nd _0.04 O ₄ Li _0.2 to _1.0 Mn _1.92 Nd _0.04 O ₄ 19. Li _1.0 Mn _1.92 Sm _0.04 O ₄ Li _0.2 to _1.0 Mn _1.92 Sm _0.04 O ₄ 20. Li _1.0 Mn _1.92 Eu _0.04 O ₄ Li _0.2 to _1.0 Mn _1.92 Eu _0.04 O ₄

Examples of the negative electrode active material that can be used in conjunction with the present invention include lithium metal, the above-mentioned lithium alloy, and carbonaceous compounds capable of occluding and releasing lithium ions or lithium metal (for example, JP-A-58-209, 86
4, 61-214, 417, 62-88, 269,
62-216, 170, 63-13, 282, 6
3-24,555, 63-121,247, 63-
121, 257, 63-155, 568, 63-2
76,873, 63-314,821, JP-A-1-2
04,361, 1-221,859, 1-274
360 etc.). The purpose of the combined use of the lithium metal and the lithium alloy is to insert lithium ions into the battery, and does not use a dissolution and deposition reaction of lithium metal or the like as a 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 electronic conductive material that does not cause a chemical change in the configured battery. Usually, natural graphite (flaky graphite, flaky graphite, earthy graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon fibers and metals (copper, nickel, aluminum, silver (JP-A-63) -1
48, 554)) One or a mixture of conductive materials such as powder, metal fiber and polyphenylene derivative (JP-A-59-20971) can be included. A combination of graphite and acetylene black is particularly preferred. Although the addition amount is not particularly limited, it is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight. For carbon and graphite, 2 to 15% by weight is particularly preferred.

Examples of the binder include starch, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone,
Tetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber, polybutadiene, fluoro rubber,
Polysaccharides such as polyethylene oxide, thermoplastic resins, polymers having rubber elasticity, and the like are used alone or as a mixture thereof. The addition amount of the binder is preferably 2 to 30% by weight. The filler, in the configured battery,
Any fibrous material that does not cause a chemical change can be used. Usually, fibers such as olefin-based polymers such as polypropylene and polyethylene, glass, and carbon are used. The amount of the filler is not particularly limited,
0-30% by weight is preferred.

As the electrolyte, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, γ-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran are used as organic solvents. , Dimethyl sulfoxide, 1,3-dioxolan,
Formamide, dimethylformamide, dioxolan,
Acetonitrile, nitromethane, methyl formate, methyl acetate, phosphoric acid triester (JP-A-60-2397)
3), trimethoxymethane (JP-A-61-4,17)
0), dioxolane derivatives (JP-A-62-1577)
1, 62-22, 372, 62-108, 474),
Sulfolane (JP-A-62-31959), 3-methyl-2-oxazolidinone (JP-A-62-4496)
1), a propylene carbonate derivative (JP-A-62-2
90,069, 62-290,071), tetrahydrofuran derivatives (JP-A-63-32,872), diethyl ether (JP-A-63-62,166), 1,3-propanesultone (JP-A-63-62,166). 63-102, 173) and a solvent in which at least one or more aprotic organic solvents are mixed and a lithium salt soluble in the solvent, for example, LiCl
O ₄ , LiBF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , L
_{iCF 3 CO 2, LiAsF 6,} LiSbF 6, LiB
₁₀ Cl ₁₀ (JP-A-57-74,974), lithium lower aliphatic carboxylate (JP-A-60-41,773), Li
AlCl ₄ , LiCl, LiBr, LiI (JP-A-60
-247,265), lithium chloroborane (Japanese Unexamined Patent Publication No.
1-1165,957) and lithium tetraphenylborate (JP-A-61-214376). Of these, LiCF is added to a mixture of propylene carbonate or ethylene carbonate and 1,2-dimethoxyethane and / or diethyl carbonate.
_An electrolyte containing ₃ SO ₃ , LiClO ₄ , LiBF ₄ and / or LiPF ₆ is preferred. The amount of these electrolytes to be added to the battery is not particularly limited, but the required amount can be used depending on the amounts of the positive electrode active material and 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 using both 1,2-dimethoxyethane and diethyl carbonate is 0.4 / 0.6 to
0.6 / 0.4) is preferred. The concentration of the supporting electrolyte is not particularly limited, but is 0.2 to 3 per liter of the electrolyte.
Molar is preferred.

In addition to the electrolytic solution, the following organic solid electrolyte can be used. For example, a polyethylene oxide derivative or a polymer containing the derivative (Japanese Unexamined Patent Publication No.
135,447), a polypropylene oxide derivative or a polymer containing the derivative, a polymer containing an ion dissociating group
(Japanese Patent Laid-Open Nos. 62-254,302 and 62-254,30)
3, pp. 63-193,954), and a mixture of a polymer containing an ion-dissociating group and the above aprotic electrolyte (U.S. Pat. Nos. 4,792,504 and 4,830,939;
2-22,375, 62-22,376, 63-2
2,375, 63-22,776, JP-A-1-95,
117), phosphate ester polymer (JP-A-61-25)
6,573) is effective. Furthermore, there is also a method of adding polyacrylonitrile to an electrolytic solution (Japanese Patent Application Laid-Open No. Sho 62-27).
8,774). In addition, a method using both an inorganic and an organic solid electrolyte is also known (JP-A-60-1768).

As the separator, an insulating thin film having a high ion permeability, a predetermined mechanical strength, and the like is used. Sheets or nonwoven fabrics made of olefin polymers such as polypropylene or glass fibers or polyethylene are used because of their resistance to organic solvents and hydrophobicity. The pore size of the separator is generally in a range useful for batteries. For example, 0.01 to 10 μm is used. The thickness of the separator is generally used in the range for batteries. For example, a thickness of 5 to 300 μm is used.
When a solid electrolyte such as a polymer is used as the electrolyte, the solid electrolyte may also serve as a separator.

It is known to add the following compounds to an electrolyte for the purpose of improving discharge and charge / discharge characteristics.
For example, pyridine (JP-A-49-108,525), triethyl phosphite (JP-A-47-4,376),
Triethanolamine (JP-A-52-72,425),
Cyclic ethers (JP-A-57-152,684), ethylenediamine (JP-A-58-87,777), n-glyme (JP-A-58-87,778), hexaphosphoric triamide (JP-A-58-787) 87, 779), nitrobenzene derivatives (JP-A-58-214,281), sulfur (JP-A-5-214,
9-8, 280), quinone imine dyes (JP-A-59-6)
8,184), N-substituted oxazolidinones and N, N'-
Substituted imidazolidinones (JP-A-59-15477)
8), ethylene glycol dialkyl ether (JP-A-59-205,167), quaternary ammonium salt (JP-A-60-30,065), polyethylene glycol (JP-A-60-41,773), Pyrrole (JP-A-60-7)
9,677), 2-methoxyethanol (JP-A-60-1985)
89,075), aluminum trichloride (JP-A-61-8).
8,466), a monomer of a conductive polymer electrode active material
(JP-A-61-161,673), triethylenephosphonamide (JP-A-61,208,758), trialkylphosphine (JP-A-62-80,976), morpholine (JP-A-62-80, 977), aryl compounds having a carbonyl group (JP-A-62-86,673), hexamethylphosphoric triamide and 4-alkylmorpholine (JP-A-62-217,575), Tertiary amines (JP-A-62-217,578), oils (JP-A-62-287,580), quaternary phosphonium salts (JP-A-63-121268), and tertiary sulfonium salts (JP-A-63-187). 121, 269).

Further, in order to make the electrolyte nonflammable, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride chloride can be contained in the electrolyte (Japanese Patent Application Laid-Open No. 48-36,678).
32). Further, in order to provide suitability for high-temperature storage, the electrolyte solution may contain carbon dioxide gas (Japanese Patent Application Laid-Open No. Sho 59-13).
4,567).

The mixture of the positive electrode and the negative electrode may contain an electrolytic solution or a supporting salt. For example, a method is known in which the above-mentioned ion-conductive polymer, nitromethane (JP-A-48-36633), and an electrolyte (JP-A-57-124870) are included. Further, the surface of the positive electrode active material can be modified. For example, the surface of a metal oxide may be esterified (JP-A-55-163779) or chelating agent (JP-A-5-163).
5-163,780), a conductive polymer (JP-A-58-163188, JP-A-59-14,274),
Polyethylene oxide, etc. (JP-A-60-97,56
There is a method of modifying the surface layer by coating the surface layer in 1). Similarly, the surface of the negative electrode active material can be modified. For example, an ion-conductive polymer or polyacetylene layer is coated (Japanese Patent Laid-Open No. 58-111276),
Surface treatment with salt (JP-A-58-142,771)
It is mentioned.

The current collector of the electrode active material may be any current collector that does not cause a chemical change in the battery. For example, for the positive electrode, in addition to materials such as stainless steel, nickel, aluminum, titanium, and calcined carbon, the surface of aluminum or stainless steel has carbon,
Nickel, titanium or silver treated, negative electrode, stainless steel, nickel, copper, titanium,
In addition to aluminum, calcined carbon, and the like, copper, stainless steel, whose surface is treated with carbon, nickel, titanium, or silver), an Al—Cd alloy, or the like is used. Oxidizing the surface of these materials is also used. The shape is
In addition to the foil, a film, a sheet, a net, a punched material, a lath body, a porous body, a foam, a molded body of a fiber group, and the like are used. The thickness is not particularly limited, but is 5 to 1
One having a thickness of 00 μm is used.

The shape of the battery can be applied to any of coins, buttons, sheets, cylinders, corners and the like. In coins and buttons, the mixture of the positive electrode active material and the negative electrode active material is used after being pressed into a pellet shape. In a sheet, a cylinder, and a corner, the mixture of the positive electrode active material and the negative electrode active material is applied on a current collector, dried, dehydrated, and pressed. The coating thickness is determined depending on the size of the battery, but is particularly preferably from 10 to 500 μm in a compressed state after drying.

The use of the non-aqueous secondary battery of the present invention is not particularly limited. For example, when mounted on an electronic device, a color notebook computer, a black-and-white notebook personal computer, a pen-input personal computer pocket (palmtop) personal computer, a 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, minidisc, electric shaver , Electronic translators, car phones, transceivers, power tools, electronic organizers, calculators, memory cards, tape recorders, radios, backup power supplies, memory cards, and the like. For other consumer use,
Examples include automobiles, electric vehicles, motors, lighting equipment, toys, game equipment, road conditioners, irons, watches, strobes, cameras, medical equipment (pacemakers, hearing aids, shoulder massagers, etc.). Furthermore, it can be used for various military purposes and space applications. Further, it can be combined with a solar cell.

[0031]

EXAMPLES The present invention will be described in more detail with reference to examples of battery production, but the scope of the present invention is not limited to these examples unless it exceeds the gist of the invention. [Synthesis example of negative electrode active material precursor, SnB _0.5 P _0.5 O ₃ ]
67.4 g of SnO, 17.4 g of B ₂ O ₃ , Sn ₂ P
102.8 g of ₂ O ₇ was mixed, sufficiently ground and mixed in an automatic mortar, set in an alumina crucible, and fired at 1000 ° C. for 10 hours in an argon gas atmosphere.
After firing, the mixture was rapidly cooled at a rate of 100 ° C./min to obtain a yellow transparent glassy negative electrode active material precursor SnB _0.5 P _0.5 O ₃ (Compound A-1). When the X-ray diffraction of the active material was measured, no diffraction line belonging to the crystal structure was detected, and it was found that the active material structure was amorphous. In the same manner, the following negative electrode active material precursor was synthesized. Sn _1.5 K _0.2 PO _3.5 (Compound A-2) Sn _1.0 Cs _0.1 Ge _0.05 Al _0.1 B _0.5 P _0.5 O _3.30
(Compound A-3)

[Example of Preparation of Positive Electrode Active Material Mixture] As a lithium manganese oxide used as a raw material of a positive electrode active material precursor, L
i _1.05 Mn _1.95 Co _0.05 O ₄ was synthesized by the following method.
Particle size 0.5-30 μm (including primary particles and secondary particles),
Chemically synthesized manganese dioxide having a BET surface area of 40 to 70 m ² / g (CMD, Mn not more than 1% by weight each as an impurity)
₂ O ₃ and Mn ₃ O _4, and 3% by weight or less of sulfate and water, and 0.5% by weight or less of Na, K, and Ca), lithium hydroxide pulverized to an average particle size of 1 to 10 μm, and Cobalt carbonate was mixed at the stoichiometric ratio of the above chemical formula, and the mixture was heat-treated at 600 ° C. for 4 hours.
And baked in the air for 18 hours while changing the temperature condition in the range of 750 ° C. to 750 ° C. After the final fired product was gradually cooled to room temperature at a rate of about 2 ° C./min, primary grinding was performed in an automatic mortar. Then control the conditions of grinding intensity and time using a vibration mill,
By combining each of the above firing temperature conditions, several types of active material particles having different particle shapes were finally prepared. As a result, in the obtained particles, the average particle size of the primary particles was 0.5 μm and the particle size of the secondary particles varied from 8 to 40 μm by laser type particle size distribution measurement. BET
The method surface area also ranges from 1 to 10 m ² / g, depending on the grinding conditions. As described above, a series of raw materials for the cathode active material precursor having different particle size distributions and specific surface areas was prepared. As a result of identifying the structure and composition by ICP and X-ray diffraction, the fired product was found to have a spinel crystal structure of Li _1.05 Mn _1.95 Co _0.05 O ₄ (compound C-
1). 2θ in X-ray diffraction using Cuα ray
= 36, the half width of the diffraction peak was about 0.3, and the intensity was 27% of the peak at 2θ = 18.6. The a-axis lattice constant of the crystal was 8.22A. It was also found that a small amount of LiMnO ₂ was mixed in the fired product. As a result of dispersing 5 g of this calcined product in 100 cc of pure water and measuring the pH, it was 8.0.
FIG. 2 is an electron microscope image of the active material particles C-1 thus produced.

Further, the above-mentioned firing method of the positive electrode active material precursor material, the molar ratio 1.02 lithium hydroxide and EMD without the addition of a transition metal other than Mn: Li _1.02 by mixing with 2, calcined Mn ₂ O ₄ was synthesized (Compound C-0). Next, Cr ₂ O ₃ , CuO,
Using Al ₂ O ₃ , baking was performed under the same heating conditions as described above, and pulverization was performed. As a result, the following positive electrode active material precursor raw materials having different average particle sizes and specific surface areas, C-2 to C-4, were obtained. Obtained. Li _1.05 Mn _1.95 Cr _0.05 O ₄ (Compound C-2) Li _1.05 Mn _1.95 Cu _0.05 O ₄ (Compound C-3) Li _1.05 Mn _1.95 Al _0.05 O ₄ (Compound C-4) In addition, these positive electrode active material precursors The values of the particle diameter and specific surface area of the body material are substantially the same in the positive electrode active material of the present invention (before and during the charge / discharge cycle) produced from these materials by a charge / discharge reaction (insertion / release of lithium ions) described later. It was confirmed that the value was equivalent to.

[Preparation Example of Electrode Mixture Sheet] 87% by weight of compound C-1, 6% by weight of flaky graphite, 3% by weight of acetylene black, and polytetrafluoroethylene as a binder Water is added to a mixture consisting of 3% by weight of an aqueous dispersion of fluoroethylene and 1% by weight of sodium polyacrylate and kneaded, and the resulting slurry is applied to both sides of a 30 μm-thick aluminum film to form a positive electrode sheet. Was made. As a result of drying and pressing the applied sheet, the applied amount of the dry film was about 340 g / m ² , and the thickness of the applied film was about 120
μm. 86% by weight of compound A-1, 6% by weight of flaky graphite, 3% by weight of acetylene black as a negative electrode active material precursor, 4% by weight of an aqueous dispersion of styrene-butadiene rubber as a binder and 4% by weight of carboxymethyl cellulose 1
Water is added to the mixture consisting of weight%, and the mixture is kneaded, and the obtained slurry is applied to both sides of a copper film having a thickness of 18 μm.
A negative electrode sheet was produced. As a result of drying and pressing the coated sheet, the coated amount of the dry film was about 70 g / m ² , and the thickness of the coated film was about 30 μm. Further, a 1: 4 mixture of flaky graphite and aluminum oxide was formed on the surface of the active material layer of the negative electrode sheet.
(Weight ratio) Protective layer made of a mixture (average thickness 5 μm)
Was applied. In the same manner, the above protective layer is applied on the surface of an active material layer prepared by applying A-2 and A-3 instead of compound A-1 as a negative electrode active material precursor, and various active materials are applied. A negative electrode sheet with a coated surface protective layer was prepared.

[Example of manufacturing a cylinder type battery]
m metal Li foil is cut into pieces each having a width of 5 mm and a length of 37 mm, and the above negative electrode active material A is dried in a dry air at a dew point of −60 ° C.
-1 to 3 were applied on the surface protective layers on both surfaces of the negative electrode sheet at regular intervals of 2 mm using a pressure roller. The amount of Li attached to the negative electrode sheet was about 110 mg by weight. The above positive electrode sheet is 35 mm
And the negative sheet is cut to a width of 37 mm.
Aluminum and nickel leads at the end of the sheet
After spot welding of the plate, the plate was dehydrated and dried at 150 ° C. for 2 hours in dry air having a dew point of −40 ° C. As shown in the cross-sectional view of the battery in FIG. 1, the positive electrode sheet (8) having been dehydrated and dried, and a porous propylene film (Selgager) as a separator.
2400) (10), a dehydrated and dried negative electrode sheet (9), and a separator (10) were laminated in this order, and spirally wound by a winder. This wound body is a nickel-plated iron bottomed cylindrical battery can (1
1) (also serving as a negative electrode terminal). 1 mol / l LiPF6 (a mixture of ethylene carbonate, butylene carbonate, and dimethyl carbonate, 2: 2: 6 (volume ratio)) was injected into the battery can as an electrolyte. A battery lid (12) having a positive electrode terminal was caulked via a gasket (13) to produce a cylindrical battery having a diameter of 14 mm and a height of 50 mm. The positive electrode terminal (12) is connected to the positive electrode sheet (8) and the battery can (11) is connected to the negative electrode sheet (9) by a lead terminal in advance.
4) was provided.

As described above, a precursor sample of a cylindrical lithium ion secondary battery obtained by combining a positive electrode active material of various chemical compositions having different particle diameters and specific surface areas and a negative electrode active material of various chemical compositions supporting Li. It was created. The battery precursor was left at room temperature for 12 hours, precharged for 1 hour under a constant current of 0.1 A, and then aged at 50 ° C. for 7 days. In this aging step, it was confirmed that all of the Li supported on the negative electrode was inserted into the negative electrode active material precursor. The battery was charged to 4.2 V at low current density and room temperature for activation. By this activation, the positive electrode active material releases about 85% of Li, and L
It was converted to a cubic spinel-type active material having a high potential of about 4.15 V with respect to i. The above-mentioned batteries were repeatedly charged and discharged under a charge end voltage of 4.2 V, a discharge end voltage of 2.8 V, and a charge / discharge current density of 1 mA / cm ² to evaluate a charge capacity.

For the above battery, the relationship between the composition of the positive electrode active material raw material, the average particle size of the positive electrode active material, the BET specific surface area, the composition of the negative electrode active material, and the discharge capacity and charge / discharge cycle life of the battery is shown. 1 In all of these batteries, the activation of the positive electrode was performed when the active material composition of the lithium manganese composite oxide was Li _0.05 to _0.20 Mn _{2-a Ma / c} O 2.
_The operation was performed to a depth of about ₄ and the active material in this composition range was used as the positive electrode active material (charged state) before the charge / discharge cycle. When these active materials were used in a charge / discharge cycle under the above voltage conditions, the composition range of the positive electrode active material in the cycle was Li _y Mn _2-a Ma _{/ c} O ₄ .
0.15 ≦ y ≦ 0.95.

Table 1. Comparison of Battery Discharge Capacity and Average Discharge Voltage Particle Size and Specific Surface Area of Positive Electrode Active Material of Active Material Negative Discharge Capacity Cycling Material Composition Particle Average Diameter (μm) Specific Surface Area Composition Capacity Retention Primary Particle Secondary Particle (m ² / G) (Ah) (%) C-0 0.5 35 1.3 A-1 0.48 87 C-0 0.5 30 1.5 A-1 0.50 87 C-0 0.522 3.5 A-1 0.52 91 C-0 0.512 8.0 A-1 0.52 90 C-0 0.58 9.0 A-1 0.52 86 C-1 0.5 33 1.3 A-1 0.47 89 C-1 0.5 29 1.5 A-1 0.49 89 C-1 0.5 21 2.7 A-1 0.50 95 C-10. 5 13 4.5 A-1 0.51 93 C-1 0.5 10 8.8 A-1 0.51 88 C-2 0.5 35 1.5 A-30 .46 88 C-2 0.5 28 1.5 A-3 0.47 88 C-2 0.5 21 2.9 A-3 0.49 94 C-2 0.5 13 5.0 A-3 0.49 92 C-2 0.5 10 9.2 A-3 0.50 87 C-3 0.5 33 1.5 A-3 0.46 88 C-3 0.5 28 1.5 A- 3 0.48 89 C-3 0.5 17 3.9 A-3 0.50 95 C-3 0.5 13 4.5 A-3 0.50 93 C-3 0.5 10 8.5 A -3 0.51 89 C-4 0.3 38 1.2 A-2 0.45 88 C-4 0.3 28 1.5 A-2 0.48 89 C-4 0.3 20 2.1 A-2 0.49 93 C-4 0.3 13 5.0 A-2 0.51 93 C-4 0.39 8.5 A-2 0.51 88

From the results in Table 1, the following tendencies are apparent. 1. The average particle size of the primary particles is 1 μm.
Under the conditions where the particle size of the secondary particles is 25 μm or less, the effect of improving the capacity and cycle life can be seen. 2. The specific surface area of the positive electrode active material is preferably in the range of 1.5 to 8.0 m ² / g, particularly 1.5 to 4.0 m ² / g in terms of cycle life. 3. Regarding the composition of the positive electrode, Mn
Active materials containing metals have comparable or lower capacities, but offer significant improvements in cycle life.

[0040]

According to the present invention, the average particle size of the primary particles is 0.05 μm to 1.0 μm, and the average particle size of the secondary particles is 2 μm to 25 μm.
μm or less, and the specific surface area of the particles is 1.5 to 8.0 m ² /
The use of a non-aqueous electrolyte-based lithium-ion battery using a positive electrode active material composed of lithium manganese composite oxide and a negative electrode active material mainly composed of tin oxide enables low-cost lithium ion having an improved cycle life. A secondary battery is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a cylinder-type secondary battery manufactured in an example, and members (1) to (14) are as described in the example.

FIG. 2 is a photograph showing a positive electrode active material C described in Examples of the present invention.
1 is an electron micrograph image of -1, which is composed of fine particles (primary particles) and secondary particles formed by agglomeration thereof.

Claims (8)

[Claims] A composition formula Li _y Mn _2-a Ma _{/ c} O _{4 + b} (M
Is a metal cation other than Li, 0 <y ≦ 1.2, 0 ≦ a ≦
(0.2, 1 ≦ c ≦ 3, 0 ≦ b <0.3) composed of a positive electrode active material mainly composed of a lithium manganese composite oxide, a negative electrode active material mainly composed of tin oxide, and a non-aqueous electrolyte The average particle diameter of the primary particles of the lithium manganese composite oxide is 0.05 μm or more and 1.0 μm or less;
A lithium ion secondary battery, wherein the average particle size of the secondary particles is 2 μm or more and 25 μm or less. 2. An average particle diameter of primary particles of the lithium manganese composite oxide is 0.1 μm or more and 0.5 μm or less,
2. The lithium ion secondary battery according to claim 1, wherein the secondary particles have an average particle size of 2 μm or more and 25 μm or less. 3. Li _y Mn _2-a Ma _{/ c} O _{4 + b} (M is Li
Metal cations other than 0, y <1.2, 0 ≦ a ≦ 0.
(2, 1 ≦ c ≦ 3, 0 ≦ b <0.3) The composition of the positive electrode active material mainly composed of the lithium manganese composite oxide, the negative electrode active material mainly composed of tin oxide, and the non-aqueous electrolyte BE of the lithium manganese composite oxide particles
A lithium ion secondary battery having a specific surface area measured by a T method in a range of 1.0 to 8.0 m ² / g. 4. The B of the lithium-manganese composite oxide particles
Lithium-ion secondary battery according to any one of claims 1 to 3, wherein the specific surface area measured by the ET method is in the range of 1.5~5.0m ² / g. 5. The composition formula Li _y Mn _2-a Ma _{/ c} O _{4 + b} (M
Is a metal cation other than Li), y, a, c, b of the lithium manganese composite oxide are 0 <y ≦ 1.2, 0 ≦ a ≦ 0.2, 1 in the charge / discharge cycle of the secondary battery. ≤
The lithium-on secondary battery according to claim 1, wherein c ≦ 3, 0 ≦ b <0.3. 6. The composition formula Li _y Mn _2-a Ma _{/ c} O _{4 + b} (0
<Y ≦ 1.2, 1 ≦ c ≦ 3, 0 ≦ b <0.3), the range of a of the lithium-manganese composite oxide is 0 <a ≦
0.2 and M is Co, Ni, Fe, Cr, Cu, T
The lithium ion secondary battery according to any one of claims 1 to 5, wherein the lithium ion secondary battery is one or more transition metal element cations selected from i. 7. A composite oxide of amorphous containing anode active material, tin mainly the general formula SNM _x O _z or Sn _y
T _1-y M _x O _z (M is at least one element selected from Al, B, P, Si, Ge, Periodic Table Group 1, Group 2, Group 3 and a halogen element; .2 ≦ x2, 0.1 ≦ y ≦
0.9, 1 ≦ z ≦ 6, and T represents a transition metal), which is an amorphous active material represented by the following formula: battery. 8. The composition formula Li _y Mn _2-a Ma _{/ c} O _{4 + b} (M
Is a metal cation other than Li, 0 <y ≦ 1.2, 0 ≦ a ≦
0.2,1 ≦ c ≦ 3,0 ≦ b <0.3), a composition formula Li _{1 + x} Mn synthesized by inserting lithium ions in a sealed battery.
_2-a M _{a / c} O _{4 + b} (0.3 <x <1.2, M is one or more metal cations except Li, 0 ≦ a ≦ 0.2, c depends on the oxidation number of M 1 ≦ c ≦ 3, 0 ≦ b <0.
The lithium secondary battery according to any one of claims 1 to 7, wherein the lithium secondary battery is prepared by a method of activating a battery precursor including the precursor according to (3) by charging.