JPH10106567A - Non-aqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-aqueous electrolyte battery excellent in the cycle characteristics with a suppressed drop of the battery capacity, in which lithium is quickly inserted into a carbon material of a negative electrode during charging, polarization of the carbon material at the ime of charging is suppressed, and there is less risk that the non-aqueous electrolytic solution is dissolved by the carbon material. SOLUTION: A non-aqueous electrolyte battery is composed of a positive electrode 1, a negative electrode 2 using carbon material, and a non-aqueous electrolytic solution, wherein the carbon material for the negative electrode 2 is structured so that the half value width of the (101) plane at X-ray diffraction is below 0.7 deg. and the ratio of the peak intensity of the (101) plane to that of the (002) plane is over 0.006.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nonaqueous electrolyte battery comprising a positive electrode, a negative electrode using a carbon material, and a nonaqueous electrolyte. The present invention relates to an improved nonaqueous electrolyte battery.

[0002]

2. Description of the Related Art In recent years, a non-aqueous electrolyte battery having a high electromotive force using a non-aqueous electrolyte as an electrolyte and utilizing 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.

In such a nonaqueous electrolyte battery, a carbon material capable of inserting and extracting lithium ions has been widely used as a negative electrode material.

[0004] In the case of a non-aqueous electrolyte battery using a carbon material for the negative electrode as described above, the reaction of electrochemically inserting lithium into the carbon material of the negative electrode during charging is generally slow, so , The non-aqueous electrolyte is decomposed by contact with the carbon material, which causes a problem that the battery capacity gradually decreases and the cycle characteristics deteriorate.

Conventionally, in a non-aqueous electrolyte battery as described above, as disclosed in JP-A-6-302315, an active material powder such as a carbon material is coated with silicon carbide whiskers, silicon nitride whiskers, titanic acid, and the like. A whisker such as a potassium whisker is mixed to improve the cycle characteristics in a nonaqueous electrolyte battery, and a whisker to improve the cycle characteristics by adding lithium carbonate to a carbon material has been proposed. .

However, even in these materials, the polarization of the carbon material used for the negative electrode during charging cannot be sufficiently suppressed as described above, and the non-aqueous electrolyte is still decomposed by contact with the carbon material. In addition, there is a problem that the battery capacity gradually decreases and the cycle characteristics deteriorate.

[0007]

SUMMARY OF THE INVENTION The present invention provides a positive electrode,
It is an object of the present invention to solve the above-described problems in a nonaqueous electrolyte battery including a negative electrode using a carbon material and a nonaqueous electrolyte, and lithium is rapidly inserted into the carbon material of the negative electrode during charging. The polarization of the carbon material during charging is suppressed, the non-aqueous electrolyte is less likely to be decomposed by the carbon material, the reduction in battery capacity is suppressed, and the non-aqueous electrolyte battery has excellent cycle characteristics. Is to be obtained.

[0008]

In order to solve the above-mentioned problems, a non-aqueous electrolyte battery according to the present invention includes a positive electrode, a negative electrode using a carbon material, and a non-aqueous electrolyte. In the electrolyte battery, as a carbon material for the negative electrode, the half width of the (101) plane in X-ray diffraction is 0.7 deg or less, and the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane is 0.1%. That is, a carbon material of 006 or more is used.

Here, in the non-aqueous electrolyte battery of the present invention, the carbon material used for the negative electrode has a high crystallinity when the half width of the (101) plane in X-ray diffraction is 0.7 deg or less, as described above. When the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane is 0.006 or more, the edge (edge) with respect to the basal plane (basal plane) of the crystal layer is formed.
Aspect ratio) has increased.

When lithium is inserted into the carbon material in the negative electrode, since lithium is inserted from the edge surface of the carbon material, the lithium is inserted into the basal surface of the crystal layer.
In the above carbon material having a large ratio of the ge plane,
The diffusion of lithium to the inside of the carbon material is quickly performed, and lithium is quickly inserted into the carbon material at the time of charging, so that polarization in the carbon material is reduced. For this reason, the decomposition of the non-aqueous electrolyte by the carbon material is suppressed, the decrease in battery capacity is reduced, and the cycle characteristics of the non-aqueous electrolyte battery are improved.

In the non-aqueous electrolyte battery according to the present invention, in order to ensure that sufficient lithium is quickly inserted into the carbon material at the time of charging to further improve the cycle characteristics of the non-aqueous electrolyte battery, the above-mentioned X It is preferable to use a carbon material having a half value width of the (101) plane of 0.6 deg or less in the line diffraction, and the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane is 0.01%.
It is preferable to use a carbon material having a peak intensity of 0 or more, more preferably 0.015 or more of the (101) plane to the (002) plane.

In the non-aqueous electrolyte battery according to the present invention, as the positive electrode material used for the positive electrode, a known positive electrode material conventionally used can be used.
Materials capable of absorbing and releasing lithium ions include, for example, manganese, cobalt, nickel, iron, vanadium,
For example, a lithium transition metal composite oxide containing at least one niobium can be used, and more specifically, LiC
_{oO 2, LiNiO 2, LiMnO 2} , it is possible to use a material such as LiFeO _2.

As the non-aqueous electrolyte in the non-aqueous electrolyte battery of the present invention, a conventionally known non-aqueous electrolyte can be used.

As the solvent in the non-aqueous electrolyte, for example, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, cyclopentanone, sulfolane, dimethyl sulfolane, 3-methyl-1,3-oxazolidin-2-yl on,
γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, butisethyl carbonate, dipropyl carbonate, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran,
Organic solvents such as 1,3-dioxolan, methyl acetate and ethyl acetate can be used alone or in combination of two or more.

The solute dissolved in the above-mentioned solvent in the non-aqueous electrolyte is, for example, LiPF
₆ , LiBF ₄ , LiClO ₄ , LiCF ₃ SO ₃ , L
iAsF ₆ , LiN (CF ₃ SO ₂ ) ₂ , LiCF ₃
A lithium compound such as (CF ₂ ) ₃ SO ₃ can be used.

[0016]

EXAMPLES Hereinafter, the nonaqueous electrolyte battery according to the present invention will be specifically described with reference to examples, and the nonaqueous electrolyte battery according to the examples of the present invention will be excellent in storage characteristics and the like. Will be clarified with reference to comparative examples. The non-aqueous electrolyte battery according to the present invention is not limited to those shown in the following examples, but can be implemented by appropriately changing the scope of the invention without changing its gist.

Example 1 In the nonaqueous electrolyte battery of this example, a positive electrode and a negative electrode prepared as described below were used, and a nonaqueous electrolyte prepared as follows was used. 13.8m outside diameter with cylindrical type as shown in
m, a non-aqueous electrolyte secondary battery having a height of 48.9 mm was produced.

[Preparation of Positive Electrode] In preparing the positive electrode, lithium-containing cobalt dioxide LiCoO ₂ heat-treated at 800 ° C. was used as a positive electrode material.

Then, the positive electrode material LiCoO ₂ , a carbon powder as a conductive agent, and a fluororesin powder as a binder are mixed in a weight ratio of 85: 10: 5, and this mixture is used as a positive electrode current collector. After the application, this was heat-treated at 150 ° C. to produce a positive electrode.

[Preparation of Negative Electrode] In preparing a negative electrode, the half-width of the (101) plane in X-ray diffraction was 0.45 deg, and the peak intensity of the (101) plane relative to the peak intensity of the (002) plane was used as a negative electrode material. Was used, and a powder of this carbon material and a fluororesin powder as a binder were mixed at a weight ratio of 85:15, and the mixture was applied to a negative electrode current collector. Thereafter, this was heat-treated at 150 ° C. to produce a negative electrode.

[Preparation of Non-Aqueous Electrolyte] In preparing a non-aqueous electrolyte, a mixed solvent in which ethylene carbonate and 1,2-dimethoxyethane were mixed at a volume ratio of 1: 1 was used. A nonaqueous electrolyte was prepared by dissolving lithium hexafluorophosphate LiPF ₆ as a solute at a ratio of 1 mol / l.

[Preparation of Battery] Then, in preparing the nonaqueous electrolyte secondary battery of this embodiment, as shown in FIG. 1, a separator was placed between the positive electrode 1 and the negative electrode 2 prepared as described above. 3, a lithium ion permeable polypropylene microporous membrane is interposed, and these are spirally wound and accommodated in a battery can 4 made of ferritic stainless steel (SUS430). 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 battery can 4 via the negative electrode lead 7. The lid 6 was electrically separated from the lid 6 by an insulating packing 8.

Comparative Example 1 In Comparative Example 1, when producing a negative electrode, the half-value width of the (101) plane in X-ray diffraction was 0.29 deg.
Natural graphite in which the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane is 0.0037 (d value =
3.354 °, Lc = 2000 °)
Otherwise, a non-aqueous electrolyte secondary battery was manufactured in the same manner as in Example 1 described above.

Then, the non-aqueous electrolyte secondary batteries of Example 1 and Comparative Example 1 produced as described above were charged at room temperature at a charging current of 600 mA (= 1 C) to a charging end voltage of 4.1 V. After that, discharge current 600mA
(= 1 C), discharge was performed to a discharge end voltage of 2.75 V, and charge and discharge were repeated as one cycle. The relationship between the number of cycles and discharge capacity was examined. The results are shown in FIG. The number of cycles until the discharge capacity was reduced to 80% of the initial discharge capacity was determined, and the results are shown in Table 1 below.

[0025]

[Table 1]

As is clear from the results shown in Table 1 and FIG. 2, the nonaqueous electrolyte secondary battery of Example 1 in which the carbon material satisfying the conditions of the present invention was used for the negative electrode did not satisfy the conditions of the present invention. As compared with the non-aqueous electrolyte secondary battery of Comparative Example 1 using the material, the decrease in the discharge capacity due to the increase in the number of cycles was slow, a stable discharge capacity was obtained over a long period, and the cycle characteristics were improved.

(Examples 2 to 11 and Comparative Example 2) Example 2
In each of the nonaqueous electrolyte secondary batteries of Comparative Example 2 to Comparative Example 2, only the carbon material of the negative electrode used in the nonaqueous electrolyte secondary battery of Example 1 was changed, and the carbon material was X-ray In the diffraction, the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane was determined in Example 1.
Each of the non-aqueous electrolyte secondary batteries was manufactured using the same 0.020 as the above, but having the half-width of the (101) plane shown in Table 2 below.

The second embodiment thus produced
Each of the nonaqueous electrolyte secondary batteries of Comparative Examples 2 to 11 and Comparative Example 2 was repeatedly charged and discharged in the same manner as described above, and the number of cycles until the discharge capacity was reduced to 80% of the initial discharge capacity was obtained. The results are shown in FIG. 3 and Table 2 below.

[0029]

[Table 2]

As is clear from the results shown in Table 2 and FIG. 3, the half width of the (101) plane in X-ray diffraction is 0.7 d.
eg or less, each of the non-aqueous electrolyte secondary batteries of Examples 1 to 11 using a carbon material satisfying the conditions of the present invention for the negative electrode,
The cycle characteristics are improved as compared with the nonaqueous electrolyte secondary battery of Comparative Example 2 using a carbon material having a half-width of the (101) plane of 0.75 deg and not satisfying the conditions of the present invention,
In particular, in each of the nonaqueous electrolyte secondary batteries of Examples 1 to 9 in which the half-width of the (101) plane was 0.6 deg or less, the cycle characteristics were further improved when the number of cycles was 900 or more.

(Examples 12 to 26 and Comparative Example 3) In each of the nonaqueous electrolyte secondary batteries of Examples 12 to 26 and Comparative Example 3, the negative electrode used in the nonaqueous electrolyte secondary battery of Example 1 was used. Of the (101) plane in X-ray diffraction is 0.45 deg, which is the same as that in Example 1, while (00)
Each non-aqueous electrolyte secondary battery was manufactured using a battery having a ratio of the peak intensity of the (101) plane to the peak intensity of the (2) plane having a value shown in Table 3 below.

Then, the embodiment 1 manufactured as described above was used.
For each of the non-aqueous electrolyte secondary batteries of Examples 2 to 26 and Comparative Example 3, charge and discharge were repeated in the same manner as described above, and the number of cycles until the discharge capacity was reduced to 80% of the initial discharge capacity was calculated. And the results are shown in FIG. 4 and Table 3 below.

[0033]

[Table 3]

As is clear from the results shown in Table 3 and FIG. 4, when the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane in X-ray diffraction is 0.006 or more,
Each of the nonaqueous electrolyte secondary batteries of Examples 1 and 12 to 25 using a carbon material satisfying the conditions of the present invention for the negative electrode,
The ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane is 0.005, and the cycle characteristics are lower than those of the nonaqueous electrolyte secondary battery of Comparative Example 3 using a carbon material not satisfying the conditions of the present invention. And (002)
Example 1 and Examples 16 and 2 in which the ratio of the peak intensity of the (101) plane to the peak intensity of the plane became 0.010 or more.
In each of the nonaqueous electrolyte secondary batteries of No. 6, the number of cycles was 9
In each of Examples 1 and 21 to 26, the cycle characteristics were further improved at the time of 00 or more times, and the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane was 0.015 or more. In the nonaqueous electrolyte secondary battery, the cycle characteristics were further improved when the number of cycles was 950 or more.

[0035]

As described above in detail, in the nonaqueous electrolyte battery according to the present invention, as a carbon material used for the negative electrode, the half width of the (101) plane in X-ray diffraction is 0.7.
deg or less, and the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane was 0.0%.
Since the ratio of the edge plane to the basal plane of the crystal layer was increased at 06 or more, lithium was quickly inserted into the carbon material at the time of charging, and the polarization of the carbon material was reduced. Decomposition of the non-aqueous electrolyte was suppressed, and a decrease in battery capacity was reduced, so that a non-aqueous electrolyte battery having excellent cycle characteristics was obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an internal structure of a nonaqueous electrolyte secondary battery produced in an example of the present invention and a comparative example.

FIG. 2 is a diagram showing the relationship between the discharge capacity and the number of cycles in the nonaqueous electrolyte secondary batteries of Example 1 and Comparative Example 1.

FIG. 3 is a diagram showing the relationship between the half width of the (101) plane and the number of cycles in a carbon material used for a negative electrode of a nonaqueous electrolyte secondary battery.

FIG. 4 shows (101) with respect to the peak intensity of the (002) plane in the carbon material used for the negative electrode of the nonaqueous electrolyte secondary battery.
FIG. 4 is a diagram illustrating a relationship between a peak intensity ratio of a surface and the number of cycles.

[Explanation of symbols]

 1 Positive electrode 2 Negative electrode

Continued on the front page (72) Inventor Toshiyuki Noma 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Koji Nishio 2-5-2-5 Keihanhondori, Moriguchi-shi, Osaka No. Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A non-aqueous electrolyte battery comprising a positive electrode, a negative electrode using a carbon material, and a non-aqueous electrolyte, wherein the carbon material in the negative electrode is determined by X-ray diffraction (101).
The half-value width of the plane is 0.7 deg or less, and the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane is 0.2.
A nonaqueous electrolyte battery using a carbon material of 006 or more. 2. The non-aqueous electrolyte battery according to claim 1, wherein the X-ray diffraction of the carbon material in the negative electrode has a half width of the (101) plane of 0.6 deg or less. . 3. The non-aqueous electrolyte battery according to claim 1, wherein the ratio of the peak intensity of the (101) plane to the peak intensity of the (002) plane in the X-ray diffraction of the carbon material in the negative electrode is 0. 010 or more.