JPH10144292A - Non-aqueous electrolyte battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrict the deterioration of the positive electrode material at the time of charge and discharge, and improve the charging and discharging cycle characteristic of a non-aqueous electrolyte battery by bonding the positive electrode material of the non-aqueous electrolyte battery provided with a positive electrode made of the crystal positive electrode material, which can store and discharge lithium, with the non-crystal compound having lithium ion conductivity. SOLUTION: V2 O5 having lithium ion conductivity is mixed in the positive electrode material LiNi0.9 Co0.7 O2 having a mean grain diameter at about 5 micron at 0.5-15wt.% in relation to the positive electrode material, and they are heated, and thereafter, they are quickly cooled so as to obtain the compound. A predetermined quantity of the conductive agent and the binder are mixed in this compound so as to adjust the slurry. This slurry is applied on both surfaces of a positive electrode collector, which is formed of an Al foil, by doctor blade method, and heating is performed in the vacuum condition so as to obtain a positive electrode. In the case where MoS2 , MnO2 , Li-alumina, LiTi2 (PO4 )3 is used as a non-crystal compound having lithium ion conductivity, similar result can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-aqueous electrolyte battery including a positive electrode using a crystalline positive electrode material capable of inserting and extracting lithium, a negative electrode, and a non-aqueous electrolyte. The present invention relates to a non-aqueous electrolyte battery having improved cycle characteristics.

[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, as a cathode material, a transition metal oxide such as LiNiO ₂ or LiCoO ₂ capable of occluding and releasing lithium and a crystalline metal such as a metal chalcogen compound are generally used. The compound was used.

Here, since the above-described positive electrode material generally has low electron conductivity, when a positive electrode is manufactured using such a positive electrode material, a conductive agent such as graphite is conventionally added to the positive electrode material. The addition has been performed to improve the electron conductivity of the positive electrode.

[0005] However, even when such a positive electrode in which a conductive agent such as graphite is added to the positive electrode material is used for a non-aqueous electrolyte battery, the above-mentioned positive electrode is charged and discharged in this non-aqueous electrolyte battery. There was a problem that lithium ions did not sufficiently move between the materials, the reaction during charging and discharging became uneven, the cathode material gradually deteriorated, and the cycle characteristics deteriorated.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a nonaqueous electrolyte battery including a positive electrode using a crystalline positive electrode material capable of inserting and extracting lithium, a negative electrode, and a nonaqueous electrolyte. The problem is to improve the mobility of lithium ions between the positive electrode materials, suppress the deterioration of the positive electrode materials during charging and discharging, and improve the charge / discharge cycle characteristics of non-aqueous electrolyte batteries. It is an object to improve the

[0007]

In order to solve the above-mentioned problems, a non-aqueous electrolyte battery according to the present invention has a positive electrode using a crystalline positive electrode material capable of inserting and extracting lithium, and a negative electrode. In a non-aqueous electrolyte battery provided with a non-aqueous electrolyte, the above-mentioned crystalline positive electrode material is joined by an amorphous compound having lithium ion conductivity.

When the crystalline cathode material is joined by an amorphous compound having lithium ion conductivity as in the non-aqueous electrolyte battery according to the present invention, lithium ions are converted into the lithium ion conductivity during charge and discharge. Quickly move between the crystalline positive electrode materials through the amorphous compound having, the reaction at the time of charge and discharge becomes uniform in the positive electrode material, the deterioration of the positive electrode material is suppressed, and in the non-aqueous electrolyte battery, The charge / discharge cycle characteristics and the like are improved.

Here, when bonding the crystalline cathode material with an amorphous compound having lithium ion conductivity, lithium ions pass between the crystalline cathode materials through the amorphous compound having lithium ion conductivity. It is preferable that the crystalline cathode material is sintered and bonded to an amorphous compound having lithium ion conductivity so as to be quickly moved.

When the crystalline cathode material is joined by an amorphous compound having lithium ion conductivity, if the amount of the amorphous compound is small, the joining of the crystalline cathode material is insufficient. This is not performed, and lithium ions cannot be sufficiently transferred between the cathode materials. On the other hand, when the amount of the amorphous compound is large, contact between the cathode materials is deteriorated, and the mobility of lithium ions between the cathode materials is reduced. Since the charge and discharge characteristics are deteriorated due to the decrease or the ratio of the positive electrode material in the positive electrode, it is preferable that the ratio of the amorphous compound be in the range of 1 to 10% by weight.

Here, in the non-aqueous electrolyte battery of the present invention, as the crystalline positive electrode material used for the positive electrode, a crystalline positive electrode material generally used conventionally can be used. A transition metal oxide containing at least one of Co, Mn and Fe, TiS ₂ , M
A metal chalcogen compound such as oS ₂ can be used. In particular, a lithium-containing compound represented by LiNix Co1-x O ₂ (x is 0 ≦ x ≦ 1) having excellent ability to insert and extract lithium ions is used. It is preferable to use a transition metal oxide.

On the other hand, as the amorphous compound having lithium ion conductivity for bonding the above-mentioned crystalline positive electrode material, for example, V ₂ O ₅ , MoS ₂ , MnO ₂ , Li-alumina, LiTi ₂ (PO ₄ ) A material in which ₃ etc. are in an amorphous state can be used.

In the nonaqueous electrolyte battery according to the present invention, as the negative electrode material used for the negative electrode, a material capable of inserting and extracting lithium ions can be used in addition to metallic lithium. , Organic materials such as fired bodies, Li-Al, Li-In, Li-
Sn, Li-Pb, Li-Bi, Li-Ga, Li-S
r, Li-Si, Li-Zn, Li-Cd, Li-C
a, a lithium alloy such as Li-Ba can be used.

In the non-aqueous electrolyte battery according to the present invention, a conventionally known non-aqueous electrolyte or the like can be used as the non-aqueous electrolyte. For example, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, cyclopentanone, sulfolane, dimethyl sulfolane, 3-methyl-1,3-oxazolidin-2-one, γ-butyrolactone, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate , Methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, butyl ethyl carbonate, dipropyl carbonate, 1,2
Organic solvents such as dimethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolan, methyl acetate, ethyl acetate and the like can be used alone or in combination of two or more.

The solute dissolved in the above-mentioned solvent in the non-aqueous electrolyte includes, for example, lithium trifluoromethanesulfonate LiCF ₃ SO ₃ , lithium hexafluorophosphate LiPF ₆ , lithium perchlorate LiClO ₄ , Lithium tetrafluoroborate LiBF
₄ , Lithium trifluoromethanesulfonate Li
A lithium compound such as N (CF ₃ SO ₂ ) ₂ can be used.

[0016]

EXAMPLES Hereinafter, the nonaqueous electrolyte battery of the present invention will be specifically described with reference to examples, and it will be compared that the nonaqueous electrolyte battery according to this example is excellent in charge / discharge cycle characteristics. Clarify with an example. In addition,
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.

(Examples 1 to 5) In Examples 1 to 5, a positive electrode, a negative electrode and a non-aqueous electrolyte prepared as described below were used, and an AA-size cylindrical shape as shown in FIG. A non-aqueous electrolyte secondary battery was manufactured.

[Preparation of Positive Electrode] To prepare a positive electrode, LiOH, Ni (OH) ₂ and Co (OH) ₂ were used, and Li: Ni: Co = Li: Ni: Co =
After mixing them in a mortar so as to have a ratio of 1: 0.9: 0.1, the mixture is heat-treated at 850 ° C. for 20 hours in an oxygen atmosphere, and then crushed in an Ishikawa-type rai mortar. A cathode material LiNi _0.9 Co _0.1 O ₂ having an average particle size of about 5 μm was obtained.

In these Examples 1 to 5,
Is the above-mentioned cathode material LiNi_0.9 Co _0.1 O_Two And Richi
V with high ionic conductivity_Two O_Five Is shown in Table 1 below.
Thus, in Example 1, 0.5% by weight, and in Example 2,
%, 5% by weight in Example 3, 10% by weight in Example 4
%, And in Example 5, 15% by weight.

Next, these mixtures were each added to 600
After heating in air at 0 ° C., the compound obtained by quenching was mixed with an artificial graphite powder as a conductive agent and a 5% by weight N-methylpyrrolidone solution in which polyvinylidene fluoride as a binder was dissolved. In addition, the above compound, artificial graphite powder as a conductive agent, and polyvinylidene fluoride as a binder were adjusted to have a weight ratio of 90: 5: 5, respectively, and these were kneaded to prepare respective slurries.

Then, each of the slurries thus prepared is applied to both surfaces of a positive electrode current collector composed of aluminum foil by a doctor blade method, and this is heat-treated under vacuum at 150 ° C. for 2 hours to form each positive electrode. Produced.

Here, when the cross section of the particle group and the cross section of the electrode in each compound used in each of the above positive electrodes were observed with a scanning electron microscope, the positive electrode material LiNi _0.9 Co _0.1 O ₂
It was confirmed that the particles of were sintered through the heterogeneous compound. Further, when this was examined by electron beam diffraction, it was confirmed that the portion of the different compound being sintered was amorphous, and the results of chemical analysis and analysis by electron probe microanalysis (EPMA) were performed. It was confirmed that the composition of this heterogeneous compound was V ₂ O ₅ . further,
When the powder of the above compound was examined by X-ray diffraction (XRD), no peak attributed to V ₂ O ₅ was observed from the diffraction pattern.

As a result, in each of the positive electrodes described above, the particles of the positive electrode material LiNi _0.9 Co _0.1 O ₂ are made of amorphous V ₂ O
It turned out that through ₅ has been sintered.

[Preparation of Negative Electrode] In preparing the negative electrode, polyvinylidene fluoride was dissolved so that 5 parts by weight of polyvinylidene fluoride as a binder was added to 95 parts by weight of natural graphite powder. A 5% by weight N-methylpyrrolidone solution was added, and the mixture was kneaded to prepare a slurry. The slurry was applied to both surfaces of a negative electrode current collector composed of copper foil, and this was applied under vacuum at 150 ° C. for 2 hours. Heat treatment was performed to produce a negative electrode.

[Preparation of Electrolyte Solution] In preparing a non-aqueous electrolyte solution, a mixed solvent of ethylene carbonate and dimethyl carbonate mixed at a volume ratio of 1: 1 was used as the solvent. Lithium phosphate LiP
The F ₆ was dissolved 1 mol / liter.

[Preparation of Batteries] In preparing the non-aqueous electrolyte secondary batteries of Examples 1 to 5, as shown in FIG. After a lithium ion permeable polypropylene microporous membrane is interposed as a separator 3, and these are spirally wound and accommodated in a battery can 4, the above-mentioned non-aqueous electrolyte is poured into the battery can 4. The positive electrode 1 is connected to the positive electrode cover 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 to insulate the battery can 4 from the positive electrode cover 6. It was electrically separated by the packing 8.

(Comparative Example 1) In Comparative Example 1, in the preparation of the positive electrodes in Examples 1 to 5 described above, V ₂ O ₅ was not added to the above-mentioned positive electrode material LiNi _0.9 Co _0.1 O _2. Except for the above, Examples 1 to 5
A non-aqueous electrolyte secondary battery was produced in the same manner as in the above case.

(Comparative Example 2) In Comparative Example 2, in the production of the positive electrodes in Examples 1 to 5, V ₂ O ₅ was added to the above-mentioned positive electrode material LiNi _0.9 Co _0.1 O ₂ in the same manner as in Example 3. Was added and mixed, and the mixture was mixed with 6% by weight.
After heating in the air at 00 ° C., this was allowed to cool without quenching.
In the same manner as in Nos. To 5, a non-aqueous electrolyte secondary battery was produced.

Here, as in Comparative Example 2, the positive electrode material
LiNi_0.9 Co_0.1 O_Two To V_Two O _Five Add and mix
The heated mixture was heated and then allowed to cool
The compound is subjected to diffraction by X-ray diffraction (XRD).
From this diffraction pattern, V_Two O_Five Attributed to
Peak was found, and the cathode material LiNi_0.9 Co_0.1O_Two
 The compound intervening in the sintering of the particles of_Two O_Five
 It turned out to be.

Next, the first embodiment manufactured as described above was used.
In order to examine the charge / discharge cycle characteristics of the non-aqueous electrolyte secondary batteries of Comparative Examples 1 to 5 and Comparative Examples 1 and 2, each of these non-aqueous electrolyte secondary batteries was charged at a charging current of 400 mA and the charge termination voltage was 4.2
After the battery was charged to 400 V, the battery was discharged to a discharge end voltage of 2.7 V at a discharge current of 400 mA. This cycle was defined as one cycle, and each nonaqueous electrolyte secondary battery was repeatedly charged and discharged. In addition to measuring the discharge capacity of the eye, the residual capacity at the 200th cycle was determined by the following equation. The results are shown in Table 1 below. Capacity remaining rate = (discharge capacity at 200th cycle / initial discharge capacity) × 100

[0031]

[Table 1]

As is clear from the results, the positive electrode material L
Each of the non-aqueous electrolyte secondary batteries of Examples 1 to 5 using the positive electrode in which the particles of iNi _0.9 Co _0.1 O ₂ were sintered via amorphous V ₂ O ₅ was made of the positive electrode material LiNi _0.9 Co _0.1 O ₂ to V
Comparative Example using the non-aqueous electrolyte secondary battery of Comparative Example 1 in which ₂ O ₅ was not added and a positive electrode in which particles of the positive electrode material LiNi _0.9 Co _0.1 O ₂ were sintered via crystalline V ₂ O ₅ As compared with the non-aqueous electrolyte secondary battery of No. 2, the capacity remaining ratio at the 200th cycle was all higher, and the charge / discharge cycle characteristics of the non-aqueous electrolyte secondary battery were improved.

When the nonaqueous electrolyte secondary batteries of Examples 1 to 5 were compared, particularly, the examples in which the amount of the amorphous V ₂ O ₅ was in the range of 1 to 10% by weight were obtained. In the non-aqueous electrolyte secondary batteries of Nos. 2 to 4, the capacity remaining ratio at the 200th cycle was high, and the amount of amorphous V ₂ O ₅ was 1 to 10% by weight.
When the ratio was within the range, the charge / discharge cycle characteristics of the nonaqueous electrolyte secondary battery were further improved.

(Examples 6 to 8) In these Examples 6 to 8, only the type of the positive electrode material used was changed in the preparation of the positive electrodes in the above Examples 1 to 5, and the following positive electrode materials were used. As shown in Table 2, in Example 6, Li
Mn ₂ O ₄ , LiFeO ₂ in Example 7, and Example 8
In this example, LiMnO ₂ was used, and 5% by weight of V ₂ O ₅ was added to each of these positive electrode materials in the same manner as in Example 3 above.
In the same manner as in the case of No. 5, a non-aqueous electrolyte secondary battery was produced.

For each of the non-aqueous electrolyte secondary batteries of Examples 6 to 8, the capacity remaining ratio at the 200th cycle was also reduced in the same manner as in Examples 1 to 5 and Comparative Examples 1 and 2. And the results are shown in Table 2 below.

[0036]

[Table 2]

As a result, LiMn ₂ O ₄ , L
Each of the nonaqueous electrolyte secondary batteries of Examples 6 to 8 using iFeO ₂ and LiMnO ₂ and using a positive electrode obtained by sintering particles of these positive electrode materials via amorphous V ₂ O ₅ also has a capacity of 200. Although the capacity remaining rate at the cycle was high, and the charge / discharge cycle characteristics of the nonaqueous electrolyte secondary battery were improved, the nonaqueous electrolyte of Example 3 above using LiNi _0.9 Co _0.1 O ₂ as the positive electrode material was used. The electrolyte secondary battery has a higher capacity residual ratio at the 200th cycle, and as a positive electrode material,
It has been found particularly large effect in the case of using the above _{LiNix Co1-x O 2 (0} ≦ x ≦ 1) lithium-containing transition metal oxide represented by.

(Examples 9 to 12) These Examples 9-1
In 2, the production of the positive electrode in the above Examples 1 to 5
In the positive electrode material LiNi_0.9 Co_0.1 O_Two Add to
Change only the type of compound having lithium ion conductivity
To form a compound having lithium ion conductivity.
Thus, as shown in Table 3 below, in Example 9, the MoS_Two 
In Example 10, MnO_Two In Example 11, Li-
Alumina was used, and in Example 11, LiTi was used._Two (PO _Four )_Three To
Used, these compounds having lithium ion conductivity
Is converted to the cathode material LiNi in the same manner as in Example 3 described above._0.9 C
o_0.1 O_Two 5% by weight each,
About the outside, it is the same as in the case of Examples 1 to 5 described above.
A non-aqueous electrolyte secondary battery was manufactured.

For each of the non-aqueous electrolyte secondary batteries of Examples 9 to 12, the capacity remaining ratio at the 200th cycle was also reduced in the same manner as in Examples 1 to 5 and Comparative Examples 1 and 2. And the results are shown in Table 3 below.

[0040]

[Table 3]

As a result, MoS ₂ , MnO ₂ , Li-alumina, L
Using iTi ₂ (PO ₄ ) ₃ , the cathode material LiNi _0.9 C
o _0. Also non-aqueous electrolyte secondary batteries of Examples 9-12 using the sintered positive electrode via ₁ O ₂ particles these amorphous compounds, residual capacity ratio at the 200th cycle is, It was as high as in Example 3 using V ₂ O ₅ as the compound having lithium ion conductivity, and the charge / discharge cycle characteristics of the nonaqueous electrolyte secondary battery were improved.

[0042]

As described above in detail, in the nonaqueous electrolyte battery according to the present invention, the positive electrode of the nonaqueous electrolyte is formed by bonding a crystalline positive electrode material with an amorphous compound having lithium ion conductivity. At the time of discharging, lithium ions move quickly between the crystalline cathode materials through the above-mentioned amorphous compound having lithium ion conductivity, so that the reaction at the time of charging and discharging is performed uniformly in the cathode material. Thus, the deterioration of the positive electrode material during charge and discharge has been suppressed.

As a result, in the non-aqueous electrolyte battery according to the present invention, a non-aqueous electrolyte battery having improved charge / discharge cycle characteristics and being usable stably and repeatedly over a long period of time was obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an internal structure of a non-aqueous electrolyte secondary battery according to an example of the present invention and a comparative example.

[Explanation of symbols]

 1 Positive electrode 2 Negative electrode

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

Claims (3)

[Claims] 1. A non-aqueous electrolyte battery comprising a positive electrode using a crystalline positive electrode material capable of inserting and extracting lithium, a negative electrode, and a non-aqueous electrolyte, wherein the crystalline positive electrode material is lithium ion A non-aqueous electrolyte battery which is joined by an amorphous compound having conductivity. 2. The non-aqueous electrolyte battery according to claim 1, wherein said crystalline positive electrode material is sintered and joined to an amorphous compound having lithium ion conductivity. Water electrolyte battery. 3. The non-aqueous electrolyte battery according to claim 1, wherein the non-aqueous electrolyte battery contains 1 to 10% by weight of an amorphous compound having lithium ion conductivity for bonding the crystalline positive electrode material. Non-aqueous electrolyte battery characterized by the above.