JPH10144349A - Solid electrolytic battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance strength of a battery sufficiently and enable stable use for a long period of time by containing a lithium ion conductive inorganic solid electrolyte of an amorphous state in a solid electrolyte battery, which is provided with a positive electrode, a negative electrode, and a lithium ion conductive polymer solid electrolyte. SOLUTION: A positive electrode 1, a lithium ion conductive polymer solid electrolyte 3, and a negative electrode 2 are layered, housed in a battery case 4 consisting of a positive electrode can 4a and a negative electrode can 4b via a positive electrode electric collector 5 and a negative electrode electric collector 6, sealed by an insulating packing 7, and a solid electrolyte secondary battery is provided. This polymeric solid electrolyte 3 is obtained by containing a solvent LiCF3 SO3 in polypropylene oxide. In this electrolyte, 2 to 35wt.% of lithium ion conductive inorganic solid electrolyte such as LiTi2 (PO4 )3 in an amorphous state is contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte battery provided with a positive electrode, a negative electrode, and a lithium ion conductive polymer solid electrolyte. The present invention relates to a solid electrolyte battery that can sufficiently prevent the battery from being easily broken due to a decrease in the charge-discharge cycle characteristics.

[0002]

2. Description of the Related Art Conventionally, an aqueous or non-aqueous electrolyte has been generally used as an electrolyte in a battery. In recent years, instead of such a liquid electrolyte, a polymer solid composed of a polymer has been used. Attention has been focused on solid electrolyte batteries using electrolytes.

That is, in such a solid electrolyte battery using a polymer solid electrolyte, since the electrolyte is not a liquid, there is no fear of liquid leakage, there is little corrosiveness, and there is no need to inject the electrolyte. In addition, there is an advantage that the structure of the battery is simple and its assembly is easy.

[0004] Here, such a solid polymer electrolyte has a lower conductivity of lithium ions than an electrolytic solution, and thus the thickness of the solid polymer electrolyte has been reduced.

[0005] However, when the polymer solid electrolyte is made thinner, its mechanical strength is reduced, and the polymer solid electrolyte is broken at the time of manufacturing a battery, and there is a problem that the positive electrode and the negative electrode are short-circuited. .

Therefore, conventionally, Japanese Patent Application Laid-Open No. 6-14 / 1994
As disclosed in Japanese Patent Publication No. 0052 and the like, it has been proposed to improve the mechanical strength of the solid polymer electrolyte by adding an inorganic oxide such as alumina to the solid polymer electrolyte.

However, when an inorganic oxide such as alumina is added to the solid polymer electrolyte as described above, if the charge and discharge are repeated in this solid electrolyte battery, the solid polymer electrolyte and the above-mentioned inorganic oxide are mixed. May react to lower the charge / discharge cycle characteristics of the solid electrolyte battery.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in a solid electrolyte battery having a positive electrode, a negative electrode, and a lithium ion conductive polymer solid electrolyte. When the thickness of the solid polymer electrolyte is reduced, the mechanical strength of the solid polymer electrolyte can be sufficiently improved, the solid polymer electrolyte can be prevented from being broken, and the positive electrode and the negative electrode can be prevented from being short-circuited. A solid electrolyte battery that can be used stably for a long period of time without causing the polymer solid electrolyte to react with the inorganic oxide during charge / discharge and deteriorating the charge / discharge cycle characteristics as in the case of adding an inorganic oxide to The task is to provide.

[0009]

In order to solve the above-mentioned problems, the solid electrolyte battery according to the present invention includes a solid electrolyte battery including a positive electrode, a negative electrode, and a lithium ion conductive polymer solid electrolyte. The above-mentioned polymer solid electrolyte contains an amorphous lithium ion conductive inorganic solid electrolyte.

When the lithium ion conductive polymer solid electrolyte contains an amorphous lithium ion conductive inorganic solid electrolyte in the lithium ion conductive polymer solid electrolyte as in the solid electrolyte battery according to the present invention, the polymer solid electrolyte is The conductivity of the lithium ion is rarely reduced, the mechanical strength of the polymer solid electrolyte is improved, and even when the thickness of the polymer solid electrolyte is reduced, the Is prevented from being short-circuited between the positive electrode and the negative electrode.

The amorphous solid electrolyte in the amorphous state has a lower reactivity than a crystalline inorganic solid electrolyte or the like. Therefore, the polymer solid electrolyte and the inorganic solid electrolyte in the amorphous state during charge and discharge are used. Are less likely to react with each other, and it is also less likely that the solid polymer electrolyte reacts to lower the charge / discharge cycle characteristics of the solid electrolyte battery as in the related art.

Here, when the amorphous solid state lithium ion conductive solid electrolyte is contained in the polymer solid electrolyte as described above, if the amount thereof is small, the strength of the polymer solid electrolyte is sufficiently improved. On the other hand, if the amount is too large, the contact between the polymer solid electrolyte and the electrode deteriorates, and the mobility of lithium ions between the electrode and the polymer solid electrolyte deteriorates. It is preferable that the content of the inorganic solid electrolyte in the molecular solid electrolyte be 2 to 35% by weight.

Here, as the polymer material constituting the lithium ion conductive polymer solid electrolyte, for example, a known polymer material such as polyethylene oxide, polypropylene oxide, and polyethylene imine can be used.

Examples of solutes added to the polymer in the polymer solid electrolyte include lithium trifluoromethanesulfonate LiCF ₃ SO ₃ , lithium hexafluorophosphate LiPF ₆ , lithium tetrafluoroborate LiBF ₄ , perchloric acid Lithium LiClO ₄ , lithium trifluoromethanesulfonimide LiN (CF
₃ SO ₂ ) ₂ or the like can be used.

Further, when adding the above-mentioned solute, a solvent capable of dissolving the above-mentioned solute may be added, and the above-mentioned solid polymer electrolyte may be used in the form of a gel. , Propylene carbonate, ethylene carbonate, γ-butyrolactone, butylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate, diethyl carbonate, and the like.

On the other hand, as the amorphous lithium ion conductive inorganic solid electrolyte to be contained in the above-mentioned polymer solid electrolyte, for example, Li ₃ N, LiTi ₂
(PO ₄ ) ₃ , Li-βAl ₂ O ₃ , LiI, LiI-
Li ₂ SP ₂ O ₅ , LiI-Li ₂ SB ₂ S ₃ , L
_{iI-Li 3 N-LiOH,} Li 2 O-B 2 O 3, Li
The _{2 O-V 2 O 3 -SiO} 2, inorganic solid electrolytes, such as LiTaO ₃ can be used after the amorphous state.

In this solid electrolyte battery, as a positive electrode material used for the positive electrode, a transition metal compound capable of inserting and extracting lithium can be used. For example, manganese, cobalt, nickel, vanadium and niobium can be used. A transition metal oxide containing at least one kind can be used.

In the solid electrolyte battery, as the negative electrode material used for the negative electrode, metallic lithium or an alloy, oxide or carbon material capable of inserting and extracting lithium can be used.

[0019]

EXAMPLES Hereinafter, the solid electrolyte battery according to the present invention will be described with reference to specific examples, and comparative examples will be used to clarify the advantages of the solid electrolyte battery according to this example. It should be noted that the solid electrolyte battery of 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 13 and Comparative Examples 1 and 2) In Examples 1 to 13 and Comparative Examples 1 and 2, a positive electrode, a negative electrode and a solid polymer electrolyte were prepared as follows. A flat-type solid electrolyte secondary battery as shown in FIG. 1 was obtained.

[Preparation of Positive Electrode] In preparing a positive electrode, lithium-containing cobalt dioxide LiCoO ₂ heat-treated at a temperature of 700 to 900 ° C. was used as a positive electrode material.
This positive electrode material, a carbon powder as a conductive agent, and a fluororesin powder as a binder were mixed in a weight ratio of 85: 10: 5, and the mixture was applied to a positive electrode current collector by a doctor blade method so as to have a thickness. After coating so as to have a thickness of about 80 μm, this was subjected to a vacuum heat treatment at a temperature of 100 to 150 ° C. to produce a disk-shaped positive electrode.

[Preparation of Negative Electrode] In preparing the negative electrode, graphite powder having an average particle diameter of 10 μm was used as a negative electrode material, and this graphite powder was mixed with a fluororesin as a binder in 9 parts.
The mixture was mixed at a weight ratio of 5: 5, and the mixture was applied on a negative electrode current collector to a thickness of about 70 μm by a doctor blade method. A negative electrode in the shape of was prepared.

[Preparation of Polymer Solid Electrolyte] Examples 1 to 1
In No. 3, titanium oxide TiO ₂ and lithium carbonate Li
₂ CO ₃ and ammonium phosphate (NH ₄ ) H ₂ PO ₄ are mixed, and the mixture is calcined at a temperature of 800 to 1000 ° C. for 2 to 8 hours. A solid electrolyte LiTi ₂ (PO ₄ ) ₃ was obtained.

Then, 1 mol / l of lithium perchlorate LiClO ₄ was dissolved in a mixed solvent of ethylene carbonate and dimethyl carbonate in a ratio of 4: 6 with respect to the acrylate monomer shown in the following chemical formula 1. A solution was prepared by adding the solution at a weight ratio of 1: 4, and the above-mentioned inorganic solid electrolyte LiT in an amorphous state was added thereto.
i ₂ (PO ₄ ) ₃ is 0.5 to 4 as shown in Table 1 below.
0.0% by weight, and then applied on the positive electrode to a thickness of 25 to 100 μm.
Output 2 from the electro-curtain type electron beam irradiation device
Polymerization was performed by irradiating an electron beam at 00 kV and an irradiation dose of 2 to 5 Mrad to produce a gelled polymer solid electrolyte on each positive electrode.

[0025]

Embedded image

On the other hand, in Comparative Example 1, the inorganic solid electrolyte LiTiO ₂ (PO
₄ ) A gel polymer electrolyte was formed on the positive electrode in the same manner as in each of the above Examples except that ₃ was not added.

In Comparative Example 2, the above-mentioned
Fused inorganic solid electrolyte LiTiO_Two (PO
_Four )_Three Instead of the crystalline inorganic solid electrolyte LiTi_Two 
(PO _Four )_Three 15% by weight
About the positive electrode in the same manner as in each of the above embodiments.
A polymer solid electrolyte in a gel state was prepared.

[Production of Battery] In producing each of the solid electrolyte secondary batteries of Examples 1 to 13 and Comparative Examples 1 and 2, as shown in FIG. The positive electrode can 4 a and the negative electrode can 4 are overlapped on the positive electrode 1 on which the polymer solid electrolytes 3 are formed as described above, and the polymer solid electrolyte 3 is sandwiched between the positive electrode 1 and the negative electrode 2.
b, the positive electrode 1 is connected to the positive electrode can 4 a via the positive electrode current collector 5, and the negative electrode 2 is connected to the negative electrode can 4 b via the negative electrode current collector 6. The positive electrode can 4a and the negative electrode can 4b were electrically insulated by the insulating packing 7. Then, the chemical energy generated inside each solid electrolyte secondary battery is transferred to the positive electrode can 4a and the negative electrode can 4b.
From both terminals are taken out as electric energy.

Next, Example 1 manufactured as described above was used.
Each of the solid electrolyte secondary batteries of Comparative Examples 1 to 13 and Comparative Examples 1 and ² was charged to 4.2 V at a charging current density of 100 μA / cm ² in an atmosphere of 25 ° C., respectively.
The battery was discharged to 2.75 V at a discharge current density of 100 μA / cm ² , and charge / discharge was repeatedly performed with such charge / discharge as one cycle.
The discharge capacity at the time of the 00 cycle was measured, and the results are shown in Table 1 below.

[0030]

[Table 1]

As is clear from these results, the polymer solid
Inorganic solid electrolyte L in amorphous state in electrolyte
iTi_Two (PO_Four )_Three Each of Examples 1 to 13 containing
Solid electrolyte secondary batteries are made of amorphous inorganic
Solid electrolyte LiTi_Two (PO _Four )_Three Did not contain
The solid electrolyte secondary battery of Comparative Example 1 and the crystalline inorganic solid
Degraded LiTi_Two (PO_Four )_Three Of Comparative Example 2 containing
Compared to body electrolyte secondary battery, at 100 cycles
The decrease in discharge capacity is small, and the solid electrolyte secondary
The charge-discharge cycle characteristics in the pond were improved.

When the solid electrolyte secondary batteries of Examples 1 to 13 were compared, in particular, the amorphous inorganic solid electrolyte LiTi ₂ (PO ₄ ) ₃ in the polymer solid electrolyte was 2.0 to 35%. In the solid electrolyte secondary batteries of Examples 3 to 11 added in the range of 0.0% by weight, the decrease in discharge capacity at 100 cycles was smaller, and the charge / discharge cycle characteristics were further improved.

Examples 14 to 26 and Comparative Example 4 In Examples 14 to 26, the above Examples 1 to 13
In the case of the solid electrolyte secondary battery described above, and in the preparation of the polymer solid electrolyte, only the type of the inorganic solid electrolyte in an amorphous state to be contained in the polymer solid electrolyte was changed.

In Examples 14 to 26, vanadium sesquioxide V ₂ O ₃ and lithium carbonate Li ₂
A mixture of CO ₃ and silicon dioxide SiO ₂ is 8
After baking at a temperature of 00 ° C. for 2 hours, this was quenched to obtain an inorganic solid electrolyte Li ₂ O ₂ − in an amorphous state.
Using V ₂ O ₃ —SiO ₂ , the inorganic solid electrolyte Li ₂ O ₂ —V ₂ O ₃ —SiO ₂ in the amorphous state was added to the polymer solid electrolyte in an amount of 0.5 to 0.5 as shown in Table 2 below.
Each of the solid polymer electrolytes was prepared by adding the coating in the range of 40.0% by weight and applying the coating to a thickness of 50 μm on each positive electrode.

On the other hand, in Comparative Example 3, the inorganic solid electrolyte Li ₂ O ₂ -V ₂ O
Instead of _3- SiO ₂ , a crystalline inorganic solid electrolyte Li ₂
O ₂ -V ₂ O ₃ -SiO ₂ is added to the polymer solid
A polymer solid electrolyte was prepared so as to be contained by weight%.

The solid electrolyte batteries of Examples 14 to 26 and Comparative Example 3 also correspond to Examples 1 to 1 described above.
3 and Comparative Examples 1 and 2, the discharge capacity at 1 cycle and the discharge capacity at 100 cycles were measured, and the results are shown in Table 2 below.

[0037]

[Table 2]

As a result, the amorphous solid electrolyte
Inorganic solid electrolyte Li_Two O_Two -V_Two O_Three 
-SiO_Two Of each of the solid electrolytes of Examples 14 to 26 containing
Rechargeable battery is an amorphous solid state electrolyte
Electrolyte secondary of Comparative Example 1 containing no electrolyte
Battery and crystalline inorganic solid electrolyte Li_Two O_Two -V_Two O _Three 
-SiO_Two The solid electrolyte secondary battery of Comparative Example 3 containing
The discharge capacity decreases at 100 cycles compared to
Low charge-discharge cycle characteristics of solid electrolyte secondary batteries
Properties, especially
Solid electrolyte Li_Two O_Two -V_Two O_Three -SiO_Two The polymer
2.0 to 35.0% by weight is added to the solid electrolyte.
In the solid electrolyte secondary batteries of Examples 16 to 24
Indicates that the discharge capacity decreases at 100 cycles.
And the charge-discharge cycle characteristics were further improved.

(Examples 27 to 39 and Comparative Example 4) In Examples 27 to 39, Examples 1 to 13
In the case of the solid electrolyte secondary battery described above, and in the preparation of the polymer solid electrolyte, only the type of the inorganic solid electrolyte in an amorphous state to be contained in the polymer solid electrolyte was changed.

In these Examples 27 to 39, after the lithium nitride Li ₃ N powder was melted at a temperature of 850 ° C., it was rapidly cooled to obtain an amorphous inorganic solid electrolyte Li ₃ N which was obtained in an amorphous state. As shown in Table 3 below, the amorphous solid electrolyte Li ₃ N in the amorphous state was contained in the polymer solid electrolyte in a range of 0.5 to 40.0% by weight. Thickness 5
Each polymer solid electrolyte was prepared by coating so as to have a thickness of 0 μm.

On the other hand, in Comparative Example 4, instead of the inorganic solid electrolyte Li ₃ N in the amorphous state,
A solid polymer electrolyte was prepared by incorporating 15% by weight of a crystalline inorganic solid electrolyte Li ₃ N into the solid polymer electrolyte.

Each of the solid electrolyte batteries of Examples 27 to 39 and Comparative Example 4 also has the characteristics of Examples 1 to 1 described above.
3 and Comparative Examples 1 and 2, the discharge capacity at one cycle and the discharge capacity at 100 cycles were measured, and the results are shown in Table 3 below.

[0043]

[Table 3]

As a result, each of the solid electrolyte secondary batteries of Examples 27 to 39 containing the amorphous solid electrolyte Li ₃ N in the polymer solid electrolyte contained the inorganic solid electrolyte in the amorphous state. In comparison with the solid electrolyte secondary battery of Comparative Example 1 not containing the solid electrolyte secondary battery and the solid electrolyte secondary battery of Comparative Example 4 containing the crystalline inorganic solid electrolyte Li ₃ N, the discharge capacity at 100 cycles was smaller. The decrease is small and the charge / discharge cycle characteristics of the solid electrolyte secondary battery are improved. In particular, the inorganic solid electrolyte Li ₃ N in the amorphous state is 2.0 to 35.0% by weight in the polymer solid electrolyte. Example 30 added in the range
In the solid electrolyte secondary batteries of Nos. To 37, the decrease in discharge capacity at 100 cycles was further reduced, and the charge / discharge cycle characteristics were further improved.

[0045]

As described above in detail, in the solid electrolyte battery according to the present invention, an amorphous lithium ion conductive inorganic solid electrolyte is contained in a lithium ion conductive polymer solid electrolyte. Therefore, the conductivity of lithium ions in the polymer solid electrolyte is rarely reduced, the mechanical strength of the polymer solid electrolyte is improved, and even when the thickness of the polymer solid electrolyte is reduced, The occurrence of the short circuit between the positive electrode and the negative electrode due to the destruction of the polymer solid electrolyte during the production was reduced.

Further, since the amorphous solid electrolyte in the amorphous state rarely reacts with the polymer solid electrolyte during charge and discharge, the discharge capacity of the solid electrolyte battery is also prevented from gradually decreasing, and the charge and discharge are prevented. A solid electrolyte battery having excellent cycle characteristics has been obtained.

[Brief description of the drawings]

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

[Explanation of symbols]

 1 Positive electrode 2 Negative electrode 3 Polymer solid electrolyte

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koji Nishio 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A solid electrolyte battery comprising a positive electrode, a negative electrode and a lithium ion conductive polymer solid electrolyte, wherein the polymer solid electrolyte contains an amorphous lithium ion conductive inorganic solid electrolyte in the polymer solid electrolyte. A solid electrolyte battery characterized by being made. 2. The solid electrolyte battery according to claim 1, wherein the content of the inorganic solid electrolyte in the polymer solid electrolyte is 2 to 35% by weight.