JP2656415B2 - Lithium crystallized glass - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium crystallized glass and a method for producing the same. More specifically, the present invention relates to a crystallized glass of a lithium-based composite oxide useful for a high energy density battery or the like having high lithium ion conductivity and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, with the advancement of technology in electronics and various industrial equipment, there has been an increasing demand for smaller batteries of high energy density and high-performance ionic conductive materials. As for lithium-based composite oxide materials, which are regarded as promising, vigorous studies are being made on their composition structure, crystal technology, vitrification technology, and the like.

For example, recently, chemically stable Li_{1 + x}
Al_xTi_2-x(PO_Four)_ThreeIs Li _ThreeN or LISICO
Reported to have high conductivity comparable to N
(J. Electrochem. Soc. 136, 590 (1989)). This new
The reported lithium-based composite oxide is expected to be
Attention has been drawn as a suggestion of a thion ion conductive solid.
You.

[0004] However, in the studies so far, all of these lithium-based composite oxides are sintered bodies, and it has not been realized to use them as crystallized glass. If a lithium-based composite oxide as a high lithium ion conductive solid can be obtained by crystallization of glass, shape imparting properties and simplification of the process can be achieved. The merits are much greater.

[0005] However, at present, only a sintered body is suggested, so that a large problem remains in the future industrial development of a highly ion-conductive lithium-based composite oxide. . Therefore, the present invention has been made in view of the above-described circumstances, and a lithium-based composite oxide as a high lithium-ion conductive solid that enables a new development in the future, the crystallized glass thereof, It is intended to provide a method for glass crystallization.

[0006]

The present invention solves the above-mentioned problems by providing the following formula (I):

[0007]

Embedded image Li _{1 + X} Al _X Ti _2-X (PO ₄ ) ₃ (0 ≦ X ≦ 1.
0)

A crystallized glass comprising a lithium-based composite oxide represented by the formula: The present invention also provides a method for producing a lithium-based crystallized glass including the above-mentioned crystallized glass. That is, the present invention provides a lithium-based composite oxide represented by the formula (I), which is attracting attention as a high lithium-ion conductive solid, not as a sintered body but as a crystallized glass. Disclose a novel material constitution and a method therefor, which are essential features and have not been known so far.

Further, in the present invention, usually,
For lithium-based composite oxides that do not turn into
Ca for_Three(PO_Four)_TwoUsing this Ca_Three(PO
_Four) _TwoMethod for producing two-phase precipitated crystallized glass with
There is the first feature above. In this case, lithium-based composite oxidation
Things and Ca_Three(PO_Four)_TwoIs melted and vitrified, and then
Heat treatment for crystallization. The second feature is this
The lithium-based composite oxide thus obtained and Ca_Three(PO
_Four)_TwoAcid treatment of the crystallized glass with_Three(PO_Four)
_TwoTo obtain porous lithium-based crystallized glass
It is in. This porosity makes continuous pores
Crystallized glass is realized.
Lithium ion useful as a catalysis electrode material
Conductive material can be selectively obtained.

[0010] Lithium-based composite oxides include, in addition to Li,
Materials composed of various elements such as Al, Ti, Zr, Nb, Cr, W, Mo, Hf, and P are used. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0011]

EXAMPLE LiCO ₃ , TiO ₂ (anatase), Al
(OH) ₃ and H ₃ PO ₄ (85% solution), and further Ca
Using CO ₃ as a raw material, (1 + x) Li ₂ O · 6.6 CaO ·
_{(4-2x) TiO 2 · xAl 2} O 3 · 5.2 P 2 O
_The mixture was placed in a silica glass beaker at ₅ (molar ratio), stirred after adding water, dried, heated to 200 ° C., and held for 12 hours.

More specifically, the value of x is variously changed in the range of 0 to 1, and the lithium complex oxide represented by the formula (I) is mixed with Ca ₃ (PO ₄ ) ₂ . The above operation was performed with various changes in the molar ratio. The obtained dried product was put in a Pt crucible and vitrified by a usual melt quenching method. The most stable glass was obtained at the above molar ratio of 1: 1.1.

[0013] Then, continue in the air at 580 ° C for 20 hours.
And a two-stage heat treatment at 680 to 700 ° C for 12 hours.
And crystallized. By this crystallization, LiTi_Two(PO
_Four)_Three: Al and β-Ca_Three(PO_Four) _TwoPrecipitation of two phases
Dense crystallized glass without crack deformation
Was obtained.

FIG. 1 shows an X-ray diffraction (XR) when x = 0.4.
D) shows a pattern, and FIG. 2 shows a change in the electric conductivity of the crystallized glass and its mother glass with temperature. Symbols G and GC in FIG. 2 indicate a mother glass and a crystallized glass, respectively, and the number after the symbol indicates the value of x. It can be seen that the conductivity increases by several orders of magnitude when the glass is crystallized in any composition. x = 0.
4 gives maximum conductivity, 5 × 10 ^-2 s / c at 300K
m, 2 × 10 ⁻² s / m at 600K. The activation energy at this time was about 30 KJ / mol.

The electric conductivity was measured by a complex impedance plot for crystallized glass and by a direct current method for mother glass. Ti in the sample
^{The 3+} concentration was measured by ESR. As is apparent from this result, the conductivity is dramatically increased by crystallizing the glass. This is one important effect of the present invention.

Next, the obtained crystallized glass is immersed in hydrochloric acid or nitric acid. For example, 20- 10
Soak at a temperature of 0 ° C. for 24 hours. Thereby, Ca ₃
(PO ₄ ) ₂ was eluted selectively. As a result, the diameter 15
A bulk porous crystallized glass represented by the above formula (I) having continuous pores of 0 to 200 nm was obtained. This porous lithium-based composite oxide shows almost the same high conductivity as the crystallized glass shown in FIG. 2, and has a specific surface area of 40 to 70 m.
^{It was 2} and big. In the above-mentioned crystallization process, a desired shape was easily obtained by giving shapes to various shapes and further performing an acid treatment.

[0017]

As described in detail above, according to the present invention, a lithium-based composite oxide having excellent shape imparting properties and simplification of the process and having extremely high conductivity can be obtained. It is extremely useful as a battery material.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction pattern of a crystallized glass of a lithium-based composite oxide and Ca ₃ (PO ₄ ) ₂ .

FIG. 2 is a correlation diagram between the conductivity of lithium-based composite oxide Ca ₃ (PO ₄ ) ₂ and a change in temperature.

Claims (2)

(57) [Claims] (1) The following formula (I): Li _{1 + X} Al _X Ti _2-X (PO ₄ ) ₃ (0 ≦ X ≦ 1.
0) A lithium-based crystallized glass represented by the formula: 2. The method according to claim 1, wherein the lithium-based composite oxide is Ca ₃ (P
A method for producing a lithium-based crystallized glass, comprising fusing together with O ₄ ) ₂ to form a glass, then heat-treating the crystal, and further performing acid treatment to elute Ca ₃ (PO ₄ ) ₂ .