JPS5834571A - Solid electrolyte battery - Google Patents

Abstract

PURPOSE:To obtain a solid electrolyte battery which has a large energy density and a high output density, and can produce a relatively large current by stacking together a solid positive active material, a solid electrolyte which conducts lithium ions, and a solid negative active material which is a lithium ion source. CONSTITUTION:A disk-like positive active material is prepared by pressure-molding mixture powder prepared by mixing PbI2 powder with a purity of 99.9% and a grain diameter of below 200mum, and Pb powder with a purity of 99.99% and a grain diameter of below 200mum in a voluminal ratio of 80 to 20. Next, a solid electrolyte thin film consisting of an LiI-MgI2 system solid solution, a negative active material thin film made of Li and a gold electrode thin film, in that order, are layered over the above positive active material so as to obtain a solid electrolyte battery. When the iodide of at least one element chosen from among magnesium and calcium is added to or solidified into the solid electrolyte made of lithium iodide as described above, the lithium-ion conducting property of the solid electrolyte is increased. As a result, even when the battery is small, a relatively large current can be released from the battery.

Description

Detailed Description of the Invention The present invention relates to a solid electrolyte battery, and more particularly relates to a solid electrolyte battery that has excellent practical n-characteristics, such as high energy density and high output density, and the ability to draw a relatively large current. Regarding batteries.

In the near future, public-funded electronic devices are becoming more compact and highly integrated using ICs, LSIs, etc., and small, thin, and
It is lightweight, has high energy density, and has no leakage and has excellent storage stability. (2) L for body batteries! ! Hopes are rising.

As a solid-state battery that satisfies this demanding demand, a lithium-based isoelectrolyte electrolyte using a lithium-ion conductive solid electrolyte has been developed and put into practical use.

Conventionally, such lithium-based batteries have been made using lithium iodide (
Using an isoelectrolyte whose main component is LiI,
A powder compact mainly composed of is sandwiched between a negative electrode active material consisting of a lithium ion source such as metallic lithium, and a positive electrode active material consisting of, for example, an iodine complex of 4-2-vinylpyridine. However, lithium iodide is usually a high-resistance material, and its lithium ion conductivity at room temperature is about 10-q.
The lithium iodide powder described above was used as a solid electrolyte. To,
A solid-state battery using a green compact containing approximately 40 mol % of α-alumina powder has been developed.

This solid electrolyte has a lithium ion conductivity of approximately 101
Although it has a relatively high value of Ω-cit-”, it is difficult to make it thin because it is a compacted powder, and the effect of reducing internal resistance cannot be sufficiently obtained.

Therefore, in order to make the solid electrolyte thinner and lower in volume, it is possible to use a thin film made of lithium iodide, but in this case, if a compacted powder of lithium iodide is used, High ionic conductivity can be utilized, but if the film is thin, lithium ions must pass through a high resistance region inside the LiI crystal, and therefore the resistance will not be low.

In order to eliminate the above-mentioned disadvantages of conventional solid electrolyte batteries, the present inventors have conducted extensive research and found that at least one iodide selected from magnesium and calcium has been added to the hedral electrolyte made of lithium iodide. The lithium ion conductivity of the solid electrolyte is increased by adding or blending these iodides, or by further converting these iodides into a solid solution. In addition, by combining such a solid electrolyte with a cathode active material whose main component is a solid electrolyte, a battery is constructed in which all of the negative diagnosis active material/bacterium percentage blind and delyte/positive electrode active material are solid. In addition, #i,
When these solid electrolytes are formed into a thin film on a positive electrode active material by vacuum evaporation or sputtering,
We have discovered that it is possible to obtain a solid electrolyte that has excellent practical nIII properties, such as making the battery thinner and lower in volume, and being able to extract a relatively large current in both energy density and output density, and have developed the present invention. It was completed.

The purpose of the present invention is to have high energy density and high power density,
It is an object of the present invention to provide a solid electrolyte battery that has excellent practical properties such as being able to draw a relatively large current.

That is, the solid electrolyte battery of the present invention each has solid,
A solid electrolyte battery comprising a bran layer of a tangential active material, a lithium ion conductive solid electrolyte, and a negative electrode active material as a lithium ion source in this order, wherein the solid electrolyte contains lithium iodide as a main component. It is characterized in that it contains at least 1111 iodides selected from magnesium and calcium, and the positive electrode active material contains iodine as a main component.

The solid electrolyte used in the present invention is composed of magnesium iodide (Mj'It) and/or calcium iodide (CaI
t) in an amount of 4 x 10-'' to 10 mol %, and the remainder is lithium iodide (LiI), but at least a portion of such LiI and M, 9I, and/or CaI is It becomes a solid solution, and furthermore, Lil, M,
91. For example, the LiI crystal, the yuIIt crystal and/or the Ca1. Compared to the case of a mixed crystal system with crystals,
This is preferable because the Li+ ion conductivity in the solid electrolyte becomes one level higher.

The solid electrolyte is LiI-M,! ? It system, Li
I-CaI.

system, or LiI-kLiI, -CaIt thread solid solution, when the solid solution is Mg2. and/or Fi
caI.

It is preferable that it contains 4×10″W moles or more. This is because if it is less than 4 x 10" molar ratio, the effect of increasing L1+ ion conductivity cannot be sufficiently obtained.

In addition, the upper limit of the amount of MgI and/or CaI added to the solid solution is
It is considered to be the solid solubility limit concentration of I*, and the concentration is not yet fully clear because it varies depending on the M production conditions, but Ca
In the polycrystal of I=, it is said that there are 5 moles, and in hllNIt, since the ionic radius of Mal+ is closer to that of Li+, it is expected that there will be more multiples.

The solid electrolyte ingot used in the present invention contains % LII powder,
A sintered body of a mixed powder containing Mjl* powder and/or caIt powder, LiI, MgI, and/or sintered CaI
, may be made of a green compact or sintered body of powder in which a part or all of these are made into a solid solution, or a thin piece of a solid solution containing LiI, MgI, and/or CaI as components, but vacuum evaporation method or By a sputtering method, a solid solution of lithium iodide and magnesium iodide and/or calcium iodide is used as a vapor deposition material or a sputtering source, or lithium iodide and at least one of magnesium iodide and calcium iodide are respectively used. The thin film formed on the cathode active material as a separate vapor deposition material or sputtering source increases the conductivity of Ll+ ions in the solid electrolyte and makes the battery thinner and smaller in volume. This is preferable because the internal resistance of the battery is low. In this case, it is preferable to layer the negative electrode active material immediately after forming a thin film of the solid electrolyte on the positive electrode active material because it is possible to prevent moisture absorption of LiI, which is the main component of the blackout electrolyte. When forming a solid electrolyte using the above-mentioned evaporation material or sputtering source by a thermal deposition method, for example, a solid electrolyte and a negative electrode active material are evaporated in a Pelger equipped with a plurality of evaporation sources (heaters). The materials are placed on separate evaporation sources (heaters) and these evaporation materials are sequentially evaporated,
A solid electrolyte and then a negative electrode active material may be formed on the positive electrode active material.

The MI electrode active material used in the present invention is silver iodide (PbI
, ) as the main component means that 2Li + PbI
*→2LiI + Pb is reacted, and the reaction product LiIXPb is preferable because both do not impair the battery reaction. The blending amount of PbI is preferably 80 to 90% sodium bicarbonate. This anode active substance jIi contains P, which is the main component.
Components other than bI may include lead, copper, aluminum, nickel, etc.

Examples of the negative electrode active material of the lithium ion source used in the present invention include metallic lithium, Li-st solid solution, and lithium alloy.

According to the solid electrolyte battery of the present invention, the solid electrolyte contains lithium iodide and at least one iodide selected from magnesium and calcium, or further,
Since at least a portion of these iodides is converted into a solid solution, the solid electrolyte has high lithium ion conductivity.

In addition, by combining such a solid electrolyte with a positive electrode active material containing silver iodide as a main component, the solid electrolyte and active material do not easily react, and the iodides are compatible with each other, resulting in low battery performance. It can be resisted.

Moreover, the active material can withstand high temperatures. Furthermore, by using the battery of the present invention in which the solid electrolyte is a thin film formed by vacuum evaporation or sputtering, the battery can be made smaller, thinner, and lighter.

Therefore, the solid electrolytic *Vt battery of the present invention has excellent practical properties such as high energy density and high output density, and can extract a relatively large current, and is superior to conventional silver oxide batteries. This battery has the advantage of being inexpensive.

Example 1 Argon (Ar) Dry? In TUX, commercially available lithium iodide and magnesium iodide were converted to MgI, respectively.

The powders were weighed so that the ratio of LiI to LiI was 0.2 mol, and these powders were mixed using an alumina mortar.

The mixed powder thus obtained was placed in a quartz angle tube, and the tube was vacuum degassed so that the pressure inside the tube was 10-" m H9 or less, and then sealed to l#. The quartz sealed tube was then placed in an electric furnace. The mixed powder was heat-treated at about 700° C. for 1 hour to melt it, and a LiI-ME I thread solution was created.

In addition, PbI with a purity of 99.9% and a particle size of 200 μm or less,
Powder and p with a purity of 99.99% and a particle size of 200 μm or less
Powder b was blended and mixed at a volume ratio of 80:20. Then, the obtained mixed powder was used at 3t/! A positive electrode active material having a diameter of 12 m and a thickness of 0.5 mm was formed by pressure molding at a pressure of 11 m.

The anode active material thus obtained was inserted into the center of a Pel jar equipped with three evaporation sources (heaters) (hereinafter referred to as first, second, and third heaters), and the above prepared material was placed on the first heater. LiI-M, 9I, system solid solution approx. 0.377
, about 1 g of metallic lithium, which is the active material of the anode, is added to the second heater soil.
．． 5 fi, 1. to the third heater. Gold Ig was placed as a polar layer.

Then, about I×10-61111 Hg was pumped into the Pelger.
Vacuum degree and space〈After vacuum degassing, heat the first heater for about 4 minutes, then heat the second heater for about 8 minutes, and then
The reactor was heated for about 6 minutes to evaporate each evaporation material in sequence, and LiI was sequentially deposited on the positive electrode active material by vacuum evaporation.
A solid electrolyte battery was obtained in which a solid electrolyte thin film made of -MliI and a solid solution, a negative electrode active material thin film also made of Li, and a gold electrolyte Sll film were stacked.

Note that an electrode layer made of a copper iAI film with a thickness of 0.05 mm was formed on the main surface of the positive electrode active material other than the bonding surface with the solid electrolyte.

Example 2 Solid solution component 19I! An LtI-CaI solid solution was prepared in the same manner as in Example 1, except that 0.2 mol of CaI was used instead of LtI.

Next, the vapor deposition material placed on the first heater is
Instead of the MgI-based solid solution, the Lil
LiI-Cal1 was sequentially deposited on the positive electrode active material consisting of PbI2-Pb thread positive pressure powder using the raw materials and method of Example 1 and Oka, except that -CaIt-based solid solution was used at approximately o, ag.
A solid electrolyte battery was obtained in which a solid electrolyte thin film made of a thread solid solution, a negative electrode active material thin film made of Li, and a gold electrode Li film were laminated.

In addition, on the other surfaces of the positive electrode active material, as in Example 1,
An electrode layer made of a copper thin film with a thickness of 0.05 m was formed.

Example 3 Four evaporation sources (heaters) (hereinafter referred to as 1st. #i2. 2nd.l)
In the central part of the Pelger, which is equipped with a
A positive electrode active material having the same composition and shape as that produced in Example I and -1 was placed on the first heat-1 [
LiIIILJo, 3. S+, 2nd? : - on ta #
It approx. 20cm, gold jll Li approx. 1.
Au #119 was placed on the 5II and 114 heaters, respectively.

The inside of the Pelger was then heated to about I
Hg vacuum degree and specifications (After vacuum degassing, heat the first heater and heater 1112 simultaneously for about 20 minutes, then heat the third heater for about 8 minutes, then heat the fourth heater for about 6 minutes. , each vapor deposition material is emitted in sequence, and a solid electrolyte thin film made of a LiI-huIm solid solution, a negative electrode active material thin film made of Li, and a gold I! A solid electrolyte battery with laminated ultra-thin films was obtained.

An electrode layer made of a copper thin film with a thickness of 0.05 m was formed on the main surface of the positive electrode active material other than the bonding surface with the solid electrolyte.

Example 4 As the vapor deposition material placed on the second heater, M,! i/11
A solid electrolyte battery was obtained using the same raw materials and method as in Example 3, except that approximately 20 da of CAII was used instead of CAII. A solid electrolyte battery was obtained using the same raw materials and method as in Example 3, except that the solid electrolyte thin film was made of only LiI instead of using .

Thus, the one-way voltage and internal resistance of each of the solid N electrolyte batteries produced in Examples 1 to 4 and Comparative Example were measured, and the results are shown in the table.

The open circuit voltage was measured using a notar deltometer with an input impedance of 100 MΩ while keeping the battery temperature at 20 to 25°C, and the internal resistance was measured using an AC: lKH
2 was applied (current-carrying area: 1.IC1F), and each measurement was made by a conventional method.

As is clear from the table, the solid electrolyte battery of the present invention has a lower solid electrolyte battery compared to a conventional battery in which the solid electrolyte is only composed of LiI.
It has approximately the same electromotive force, and the internal resistance is approximately 1/10
” is extremely low.

Claims (1)

[Claims] 1. A solid electrolyte battery comprising a positive electrode active material, a lithium ion conductive solid electrolyte, and a lithium ion source negative electrode active material, each of which is solid, stacked in this order, comprising: The solid electrolyte contains lithium iodide as the main component,
At least one selected from magnesium and calcium
1. A monolithic electrolyte battery, characterized in that the positive electrode active material contains iodide as a main component. 2. The battery according to claim 1, wherein the 111-body electrolyte is a solid solution of lithium iodide and at least one iodide selected from magnesium and calcium. 3. The II solution contains at least one iodide selected from magnesium and/or calcium at 4×lθ″
4. The battery according to claim 2, wherein the solid electrolyte contains a solid solution of lithium iodide and magnesium iodide and/or calcium iodide as a vapor deposition material or a Snohira ivy source. 5. The battery according to claims 1 to 3, wherein the solid electrolyte is a thin film formed on a positive electrode active material by a vacuum evaporation method or a snobutting method.5. Claims 1 to 3 are thin films formed on a positive electrode active material by vacuum evaporation or sputtering using at least one of magnesium and calcium iodide as separate vapor deposition materials or sputtering sources, respectively. Batteries listed.