JPH10255795A - Nonaqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte battery the decline of discharge capacity of which is not much even if charging and discharging is repeated and which has excellent cycle characteristics, by adding at least one kind among Na, K, Mg, Ca and Al to a composite oxide of Li, Co and Ni as positive electrode material. SOLUTION: LiXM1Y1 Co1- ZNiZO2 (wherein M1 is at least one kind of element of Na or K, and a condition, 0.5<=X<1.0, 0.5<X+Y1<=1.0, 0.1<=Z<=0.9 is complied with) is used for positive electrode material. LiXM2Y2 Co1- ZNiZO2 (wherein M2 is at least one kind of element of Mg and Ca, and a condition, 0.5<=X<1.0, 0.5<X+Y2/2<=1.0, 0.1<=Z<=0.9 is complied with) can be also used for the positive electrode material. LiXAlY3 Co1- ZNiZO2 (wherein a condition, 0.5<=X<1.0, 0.5<X+Y3/3<=1.0 is complied with) can be also used. Thereby, a nonaqueous electrolyte battery a decline of discharge capacity of which is not much and which has excellent cycle characteristics is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte battery provided with a positive electrode, a negative electrode, and a non-aqueous electrolyte, and particularly to a non-aqueous electrolyte battery using a composite oxide of lithium, cobalt, and nickel as a positive electrode material in the positive electrode. In a water electrolyte battery, the cycle characteristics are improved.

[0002]

2. Description of the Related Art In recent years, a nonaqueous electrolyte battery having a high electromotive force using a nonaqueous electrolyte or the like as an electrolyte and utilizing the oxidation and reduction of lithium has been used as one of new batteries having a high output and a high energy density. It became so.

[0003] In such a nonaqueous electrolyte battery, a lithium-transition metal composite oxide capable of inserting and extracting lithium is widely used as a positive electrode material for the positive electrode. In recent years, in order to obtain a nonaqueous electrolyte battery having a high flatness of a charge / discharge curve, a battery using a composite oxide of lithium, cobalt, and nickel as a positive electrode material has been used.

[0004] However, even when such a composite oxide of lithium, cobalt and nickel is used for the positive electrode material, there is a problem that the discharge capacity is gradually reduced and the cycle characteristics are poor when charging and discharging are repeated. Was.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in a non-aqueous electrolyte battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte.
In a non-aqueous electrolyte battery using the above-described composite oxide of lithium, cobalt and nickel as the positive electrode material of the positive electrode, the discharge capacity is reduced even when the positive electrode material is improved and charge and discharge are repeated. It is an object of the present invention to obtain a non-aqueous electrolyte battery which is less likely to have excellent cycle characteristics.

[0006]

According to a first aspect of the present invention, there is provided a non-aqueous electrolyte battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte. As the positive electrode material in the above positive electrode, Li _X M1 _y1 Co _{1 -Z} Ni _Z O ₂ (M1 is Na, K
At least one element of 0.5 ≦ X <1.0,
The condition of 0.5 <X + Y1 ≦ 1.0 and 0.1 ≦ Z ≦ 0.9 is satisfied. ) Was used.

According to a second aspect of the present invention, there is provided a non-aqueous electrolyte battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein Li _X M2 _{Y 2} Co _{1 is} used as a positive electrode material in the positive electrode. _-Z Ni _Z O ₂ (M2 is M
g and Ca are at least one element, and 0.5 ≦ X <
1.0, 0.5 <X + Y2 / 2≤1.0, 0.1≤Z≤
The condition of 0.9 is satisfied. ) Was used.

According to a third aspect of the present invention, there is provided a non-aqueous electrolyte battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein Li _X Al _{Y 3} Co _{1 is} used as a positive electrode material in the positive electrode. _-Z Ni _Z O ₂ (0.5 ≦
The condition of X <1.0 and 0.5 <X + Y3 / 3≤1.0 is satisfied. ) Was used.

According to a fourth aspect of the present invention, there is provided a non-aqueous electrolyte battery including a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein Li _X M1 _Y1 M2 _{Y2 is} used as a positive electrode material in the positive electrode. Al _Y3 Co _1-Z Ni _Z O
₂ (M1 is at least one element of Na and K, M2 is M
g and Ca are at least one element, and 0.5 ≦ X <
1.0, 0.5 <X + Y1 + Y2 / 2 + Y3 / 3≤1.
The condition of 0, 0.1 ≦ Z ≦ 0.9 is satisfied. ) Was used.

Here, as in the nonaqueous electrolyte battery according to the above-mentioned claims, a composite oxide of lithium, cobalt and nickel is used as a cathode material for the cathode, and Na, K, Mg, Ca , Al, at least one element is added, according to the inventor's consideration, the added element is replaced with a part of lithium, and the structure of the positive electrode material when charging and discharging is performed. The change is suppressed, the characteristics of the positive electrode material are less likely to be reduced, the decrease in the discharge capacity when charging and discharging are performed repeatedly is suppressed, and a nonaqueous electrolyte battery having excellent cycle characteristics is obtained. It is thought to be.

Here, when adding at least one element of Na, K, Mg, Ca, and Al to the composite oxide of lithium, cobalt, and nickel to partially replace lithium, the amount of substitution is determined. Is too large, the capacity per unit of the positive electrode decreases, so that Na,
When K is monovalent, Mg and Ca are divalent, and Al is trivalent, the substitution amount should not exceed 0.5.

Z, which indicates the ratio of cobalt to nickel,
Is set to be 0.1 ≦ Z ≦ 0.9 in order to obtain a non-aqueous electrolyte battery having good characteristics by containing cobalt and nickel in the positive electrode material.

On the other hand, in the nonaqueous electrolyte battery according to the present invention, as the negative electrode material used for the negative electrode, a known negative electrode material conventionally used can be used.
For example, carbon materials such as graphite and coke, metallic lithium,
Lithium alloys, metal oxides such as Li _x Fe ₂ O ₃ and Li _x WO ₂ , and conductive polymers such as polyacetylene can be used, and in particular, a non-aqueous electrolyte battery with good characteristics can be obtained. Therefore, it is preferable to use a carbon material such as graphite for the negative electrode.

The graphite or coke used as the carbon material may be used in the form of pulverized material as it is, or may be subjected to purification treatment, heat treatment at 500 to 3700 ° C., acid treatment, alkali treatment, and expansion. It may be used that has been subjected to a treatment such as chemical treatment, especially when graphite is used,
In order to obtain a sufficient capacity, the lattice plane (002
4, the plane spacing (d ₀₀₂ ) is in the range of 3.35 to 3.37 °, and the crystallite size (Lc) in the c-axis direction is 400 °.
It is preferable to use the above.

When a non-aqueous electrolyte is used as the non-aqueous electrolyte, a known solvent which has been generally used can be used as a solvent for the non-aqueous electrolyte. , Cyclic carbonates such as propylene carbonate, butylene carbonate, and vinylene carbonate, and dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, and a mixture of one or more linear carbonates such as ethyl propyl carbonate. They can be used, and it is particularly preferable to use the above-mentioned cyclic carbonate and chain carbonate in combination.

In this non-aqueous electrolyte, a known solute can be used as a solute to be dissolved in the above-mentioned solvent. For example, lithium trifluoromethanesulfonate L
iCF ₃ SO ₃ , lithium hexafluorophosphate LiP
Lithium compounds such as F ₆ , lithium perchlorate LiClO ₄ , lithium tetrafluoroborate LiBF ₄ , lithium trifluoromethanesulfonate imide LiN (CF ₃ SO ₂ ) ₂ can be used, and these solutes can be used in the above-mentioned solvent. In dissolving, generally, the concentration is set to 0.
The ratio is set to 7 to 1.5 mol / l.

Further, in the non-aqueous electrolyte battery according to the present invention, a known separator generally used conventionally can be used for the separator for separating the positive electrode and the negative electrode.

[0018]

The non-aqueous electrolyte battery of the present invention will be described below.
Examples will be specifically described, and in the case of the nonaqueous electrolyte battery in this example, reduction in capacity due to charge / discharge is reduced and charge / discharge cycle characteristics are improved. To The nonaqueous electrolyte battery according to the present invention is not limited to those described in the following examples, and can be implemented by appropriately changing the scope of the invention without changing its gist.

(Examples 1 to 15) In these examples, a cylindrical lithium secondary battery as shown in FIG. 1 was prepared by using a positive electrode, a negative electrode and a non-aqueous electrolyte prepared as follows. Produced.

[Preparation of Positive Electrode] In preparing the positive electrode, Li, Li, and Li were used so as to obtain the respective positive electrode materials shown in Table 1 below.
Na, K, M for hydroxide of each metal of Co and Ni
The hydroxides of each of the metals g, Ca, and Al were mixed at an appropriate ratio, and were fired in air at a temperature of 800 ° C. for 24 hours to obtain each positive electrode material.

Then, each of the positive electrode materials thus obtained and artificial graphite as a conductive agent are mixed at a weight ratio of 90: 5 to obtain each positive electrode mixture, and then each positive electrode mixture is combined. N-methyl-2-vinylidene fluoride as an adhesive
A solution dissolved in pyrrolidone (NMP) is added, and each positive electrode mixture and polyvinylidene fluoride are kneaded so as to have a weight ratio of 95: 5 to prepare respective slurries. Is applied on both sides of an aluminum foil by a doctor blade method,
For 2 hours to produce each positive electrode.

[Preparation of Negative Electrode] In preparing a negative electrode, the plane spacing (d ₀₀₂ ) on the lattice plane ( ₀₀₂ ) was set to 3.
An air stream is injected into the carbon lump having a crystallite size (Lc) of at least 356 ° in the c-axis direction of 1000 ° or more, and the carbon lump is jet-pulverized and then sieved to reduce the average particle size to about 10 μm. Graphite powder was obtained.

Then, a solution in which polyvinylidene fluoride as a binder is dissolved in the above NMP is added to the graphite powder, and the weight ratio of the graphite powder to polyvinylidene fluoride is 8%.
A slurry was prepared by kneading at a ratio of 5:15, and this slurry was applied to both surfaces of a copper foil as a negative electrode current collector by a doctor blade method, and dried at 150 ° C. for 2 hours under vacuum to prepare a negative electrode. did.

[Preparation of Non-Aqueous Electrolyte] In preparing a non-aqueous electrolyte, a mixed solvent of ethylene carbonate and 1,2-dimethoxyethane in a volume ratio of 1: 1 was mixed with phosphorus hexafluoride. 1 mol / l of lithium phosphate LiPF ₆
To prepare a non-aqueous electrolyte.

[Preparation of Battery] In preparing a battery, as shown in FIG. 1, a lithium ion permeable polypropylene was used as a separator 3 between each positive electrode 1 and negative electrode 2 prepared as described above. These are wound in a spiral shape with a microporous membrane of
Then, the above-mentioned non-aqueous electrolyte is poured into each battery can 4 and sealed, and the positive electrode 1 is connected to the positive electrode lid 6 via the positive electrode lead 5 and the negative electrode 2 is connected to the negative electrode lead. 7
, And the battery can 4 and the positive electrode cover 6 were electrically separated by the insulating packing 8, thereby producing each lithium secondary battery.

Comparative Example 1 In this comparative example, as a positive electrode material for a positive electrode, as shown in Table 1 below, Li was used.
A lithium secondary battery was manufactured in the same manner as in each of the above examples except that Co _0.5 Ni _0.5 O ₂ was used.

Then, for each of the lithium secondary batteries of Examples 1 to 15 and Comparative Example 1 produced as described above,
Each was charged at room temperature at a charging current of 200 mA to a charging end voltage of 4.1 V, and then discharged at a discharging current of 200 mA to a discharging end voltage of 2.75 V. This was defined as one cycle, and charge and discharge were repeated for 200 cycles. The initial capacity and the capacity after 200 cycles were obtained, and the deterioration rate per cycle was obtained. The results are shown in Table 1 below.

[0028]

[Table 1]

As is clear from the results, Li and Co
Na, K, and M with respect to the composite oxide of
In each of the lithium secondary batteries of Examples 1 to 15 to which the elements of g, Ca, and Al were added, the deterioration rate per cycle was lower than that of the lithium secondary battery of Comparative Example 1 in which these elements were not added. As compared with the above, the cycle characteristics were improved. When comparing the lithium secondary batteries of Examples 1 to 15, Na, K, Mg, Ca, A
The larger the amount of 1 added, the lower the initial capacity of the battery. Therefore, as described above, Na, K, Mg, Ca,
It was preferred that the amount of Al added not exceed 0.5 valency.

(Examples 16 to 33) In these examples, in preparing the positive electrode, Na, K, Mg, Ca, and A were used with respect to the hydroxides of the respective metals Li, Co, and Ni.
1 and 2 or more of the metal hydroxides were combined and mixed to obtain each positive electrode material shown in Table 2 below.

Each lithium secondary battery was manufactured in the same manner as in Examples 1 to 15 except that the positive electrode materials shown in Table 2 were used.

The charge and discharge of each of the lithium secondary batteries of Examples 16 to 33 were repeated in the same manner as described above to obtain the initial capacity and the capacity after 200 cycles. Was determined, and the results are shown in Table 2 below.

[0033]

[Table 2]

(Examples 34 to 36) In these examples, the same Li material as in Example 1 was used as the positive electrode material.
_{While 0.9} Na _0.1 Co _0.5 Ni _0.5 O ₂ is used, a cyclic carbonate and a chain carbonate are used in combination as a solvent in the non-aqueous electrolyte as shown in Table 3 below. 1: 1 of carbonate (EC) and diethyl carbonate (DEC)
In Example 35, ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) were mixed at a volume ratio of 1:
In Example 36, a mixed solvent in which ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed in a volume ratio of 1: 1 was used. Each lithium secondary battery was produced in the same manner as in Example 1 described above.

Each of the lithium secondary batteries of Examples 34 to 36 was repeatedly charged and discharged in the same manner as described above, and the deterioration rate per cycle when the charge and discharge were performed for 200 cycles. And the results are shown in Table 3 below.

[0036]

[Table 3]

As is apparent from the results, when the mixed solvent in which the cyclic carbonate and the chain carbonate are combined is used as the solvent in the non-aqueous electrolyte, the above-mentioned Example 1 is used.
In this case, the deterioration rate was further reduced, and a lithium secondary battery having excellent charge / discharge cycle characteristics was obtained.

[0038]

As described in detail above, in the nonaqueous electrolyte battery according to the present invention, a composite oxide of lithium, cobalt and nickel is used as a cathode material for the cathode, and Na, K, Mg, Ca, Since at least one element of Al is added in an appropriate amount, the characteristics of the positive electrode material are less likely to be deteriorated by charge and discharge, and a decrease in discharge capacity when charge and discharge are repeatedly performed is suppressed. A non-aqueous electrolyte battery having excellent cycle characteristics was obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing an internal structure of each nonaqueous electrolyte battery of an example of the present invention and a comparative example.

[Explanation of symbols]

 1 Positive electrode 2 Negative electrode

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masahisa Fujimoto 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Toshiyuki Noma 2-chome Keihanhondori, Moriguchi-shi, Osaka No. 5-5 Sanyo Electric Co., Ltd. (72) Inventor Koji Nishio 2-5-5 Sanyo Electric Co., Ltd. (72) Inventor Hiroshi Watanabe Keihan Motodori, Moriguchi, Osaka 2-5-5 Sanyo Electric Co., Ltd.

Claims (4)

[Claims] 1. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein Li _X M1 _y1 Co _{1 -Z} Ni _Z O ₂ (M1 is Na, K
At least one element of 0.5 ≦ X <1.0,
The condition of 0.5 <X + Y1 ≦ 1.0 and 0.1 ≦ Z ≦ 0.9 is satisfied. A non-aqueous electrolyte battery comprising: 2. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein Li _X M2 _Y2 Co _{1 -Z} Ni _Z O ₂ (M2 is Mg, C
a at least one element, and 0.5 ≦ X <1.
0, 0.5 <X + Y2 / 2≤1.0, 0.1≤Z≤0.
Condition 9 is satisfied. A non-aqueous electrolyte battery comprising: 3. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte, wherein Li _X Al _Y3 Co _{1 -Z} Ni _Z O ₂ (0.5 ≦ X <
1.0, 0.5 <X + Y3 / 3≤1.0, 0.1≤Z≤
The condition of 0.9 is satisfied. A non-aqueous electrolyte battery comprising: 4. A non-aqueous solution comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte
In the electrolyte battery, the positive electrode material of the above positive electrode is
And Li_XM1_Y1M2_Y2Al_Y3Co_1-ZNi _ZO_Two(M
1 is at least one element of Na and K, M2 is Mg, C
a at least one element, and 0.5 ≦ X <1.
0, 0.5 <X + Y1 + Y2 / 2 + Y3 / 3≤1.0,
The condition of 0.1 ≦ Z ≦ 0.9 is satisfied. )
Characteristic non-aqueous electrolyte battery.