阅读说明：本技术 一种玻璃态锂离子固态电解质及其制备方法 (Glass state lithium ion solid electrolyte and preparation method thereof ) 是由 汤卫平 张竞择 吴勇民 王琴 吴晓萌 田文生 陈玉华 朱蕾 贾荻 于 2020-04-17 设计创作，主要内容包括：本发明涉及一种锂离子固态电解质及其制备方法,属于固态锂电池技术领域。本发明中首先合成固态钠离子导体(NASICON),然后在锂离子的溶剂或熔盐中进行钠/锂离子的离子交换反应,合成锂离子固态电解质,然后通过热处理,得到同锂离子固态电解质组成相同的玻璃态锂离子导体。得到的玻璃态锂离子导体显示了等同或高于钠离子导体的离子导电率,该锂离子导体显示了对锂金属良好的稳定性,是优良的锂离子固态电解质。(The invention relates to a lithium ion solid electrolyte and a preparation method thereof, belonging to the technical field of solid lithium batteries. In the invention, a solid sodium ion conductor (NASICON) is synthesized firstly, then the ion exchange reaction of sodium/lithium ions is carried out in the solvent or molten salt of lithium ions to synthesize the lithium ion solid electrolyte, and then the glassy state lithium ion conductor which has the same composition with the lithium ion solid electrolyte is obtained through heat treatment. The obtained glassy lithium ion conductor shows an ion conductivity equal to or higher than that of a sodium ion conductor, shows good stability to lithium metal, and is an excellent lithium ion solid electrolyte.)

1. A glassy state lithium ion solid electrolyte is characterized in that the glassy state lithium ion solid electrolyte has a chemical formula of L i_1+xZr₂P_3-xSi_xO₁₂，0≤x≤3。

2. The glassy lithium ion solid electrolyte of claim 1, wherein the glassy lithium ion solid electrolyte has a chemical formula of L i₃Si₂Zr₂PO₁₂。

3. A preparation method of a glassy lithium ion solid electrolyte is characterized by comprising the following steps:

(1) putting the Na super-ionic conductor powder into a solution containing L i ions, heating and stirring to obtain a mixture;

(2) filtering the mixture obtained in the step (1), cleaning a filter cake to obtain L i super ionic conductor powder, and cleaning L i super ionic conductor powder to obtain pure L i super ionic conductor powder;

(3) and (3) carrying out heat treatment on the pure L i super ion conductor powder obtained in the step (2), wherein the heat treatment temperature is 750-900 ℃, and obtaining the glassy state lithium ion solid electrolyte.

4. The method of claim 1, wherein the method comprises: in the step (1), the chemical formula of the Na super-ion conductor powder is Na_1+xZr₂P_3-xSi_xO₁₂，0≤x≤3。

5. The method of claim 4, wherein the lithium ion precursor comprises: the Na super-ion conductor powder is Na₃Si₂Zr₂PO₁₂、Na₄Zr₂(SiO₄)₃、NaZr₂(PO₄)₃、Na₃Hf₂Si₂PO₁₂、Na₃La(PO₄)₂、Na_1.3Ti_1.7Al_0.3(PO₄)₃、Na₃V₂(PO₄)₃Or Na_2.96Nb_0.04Zr_1.96Si₂PO₁₂。

6. The method according to claim 3, wherein in the step (1), the L i ion solution contains ionic liquid as solvent, and the ionic liquid is C₆H₁₁BF₄N₂、C₈H₂₀BF₄NO、C₇H₁₆BF₄N、C₈H₁₁F₆N₃O₄S₂、C₈H₁₆F₆N₂O₄S₂、C₆H₁₁F₂N₃O₄S₂Or C₉H₂₀F₂N₂O₄S₂。

7. The method of claim 3, wherein the lithium salt for generating L i ions in step (1) is L iClO₄、LiPF₆、LiNO₃L iCl, L iBF4, L iTFSI, L iBOB, L iDFOB or L iFSI.

8. The method of claim 3, wherein the lithium ion precursor comprises: in the step (1), the heating temperature is 50-400 ℃, and the stirring time is 2-100 h.

9. The method of claim 3, wherein the lithium ion precursor comprises: in the step (2), methanol, ethanol or deionized water is used for cleaning when cleaning.

10. The method of claim 3, wherein the lithium ion precursor comprises: in the step (3), the heat treatment temperature is 800 ℃, and the heat treatment time is 2-10 h.

Technical Field

The invention relates to a lithium ion solid electrolyte and a preparation method thereof, belonging to the technical field of solid lithium batteries.

Background

The lithium ion battery is an energy storage device with the highest energy density at present, but with the development of manufacturing technology, the energy density of the lithium ion battery gradually reaches the upper limit, and the safety problem of the lithium ion battery is increasingly highlighted due to the improvement of the energy density. The solid-state battery is expected to become an energy storage device with higher specific energy density, higher safety and longer service life than a lithium ion battery. Solid electrolytes are the most critical materials in determining the performance of solid-state batteries.

Among the current solid electrolyte materials, solid electrolytes are an immature technical field at present. The materials of solid electrolytes are classified into oxygen-containing series and sulfide series, wherein the solid electrolytes of oxygen-containing series have certain advantages in physicochemical and electrochemical stability, but the ionic conductivity is generally less than 10^-3S/cm, poor interface processability. The sulfur-based electrolyte may exceed 10 in electrical conductivity^-3S/cm, individually even up to 10^-2S/cm, but has a problem of poor physicochemical and electrochemical stability. In summary, in the existing solid electrolyte material, the ion conductivity is high (greater than 10)^-3S/cm) and satisfies physicochemical stability, electrochemical stability, and operability.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art, provides a glassy lithium ion solid electrolyte and a preparation method thereof, and has high ionic conductivity (more than 10)^-3S/cm), chemical stability, electrochemical stability and good operation performance.

The solution of the invention is:

a glassy state lithium ion solid electrolyte with a chemical formula of L i_1+xZr₂P_{3- x}Si_xO₁₂0. ltoreq. x.ltoreq.3, preferably L i₃Si₂Zr₂PO₁₂。

A method of preparing a glassy lithium ion solid electrolyte, the method comprising the steps of:

(1) putting the Na super-ionic conductor powder into a solution containing L i ions, heating and stirring, wherein an exchange reaction of Na ions and L i ions occurs in the heating and stirring process to obtain a mixture;

(2) filtering the mixture obtained in the step (1), cleaning a filter cake to obtain L i super ion conductor powder, and repeatedly cleaning L i super ion conductor powder with alcohol or distilled water to obtain pure L i super ion conductor powder;

(3) and (3) carrying out heat treatment on the pure L i super ion conductor powder obtained in the step (2), so that the crystal is converted into a glass state, and a glass state lithium ion solid electrolyte is formed.

In the step (1), the chemical formula of the Na super-ion conductor powder is Na_1+xZr₂P_3-xSi_xO₁₂0. ltoreq. x.ltoreq.3, preferably Na₃Si₂Zr₂PO₁₂、Na₄Zr₂(SiO₄)₃、NaZr₂(PO₄)₃、Na₃Hf₂Si₂PO₁₂、Na₃La(PO₄)₂、Na_1.3Ti_1.7Al_0.3(PO₄)₃、Na₃V₂(PO₄)₃、Na_2.96Nb_0.04Zr_1.96Si₂PO₁₂；

In the step (1), in the L i ion solution, the solvent is ionic liquid, and the ionic liquid is C₆H₁₁BF₄N₂、C₈H₂₀BF₄NO、C₇H₁₆BF₄N、C₈H₁₁F₆N₃O₄S₂、C₈H₁₆F₆N₂O₄S₂、C₆H₁₁F₂N₃O₄S₂Or C₉H₂₀F₂N₂O₄S₂The lithium salt generating L i ion is L iClO₄、LiPF₆、LiNO₃L iCl, L iBF4, L iTFSI, L iBOB, L iDFOB or L iFSI;

in the step (1), the heating temperature is 50-400 ℃, and the stirring time is 2-100 h;

in the step (2), methanol, ethanol or deionized water is used for cleaning when cleaning;

in the step (3), the heat treatment temperature is 750-900 ℃, and the heat treatment time is 2-10 h.

Advantageous effects

(1) The invention prepares a novel glassy state L i super ion conductor L i_1+xZr₂P_3-xSi_xO₁₂(x is more than or equal to 0 and less than or equal to 3), is suitable for solid electrolyte of a solid battery, and has the ionic conductivity of more than 10^-4S/cm, good electrochemical stability, no side reaction, good stability in air environment, good processing performance in the preparation process of the solid-state battery, and good mechanical and chemical compatibility with electrode materials.

(2) The invention proposes the use of sodium-based super-ionic conductors (NASICON, Na)_1+xZr₂P_3-xSi_xO₁₂X is more than or equal to 0 and less than or equal to 3) is used for synthesizing the glassy state lithium super-ion conductor, NASICON is put into a solvent or molten salt containing lithium ions to carry out exchange reaction of sodium and lithium ions, and an L ISICON lithium ion conductor L i with the same structure as the NASICON is formed_1+xZr₂P_3-xSi_xO₁₂(x is more than or equal to 0 and less than or equal to 3), and then the L iSICON in a crystalline state is converted into a glassy state by a heat treatment mode to form a glassy state super lithium ion conductor;

(3) in the invention, a solid sodium ion conductor (NASICON) is synthesized, and then the ion exchange reaction of sodium/lithium ions is carried out in a solvent or molten salt of lithium ions to synthesize the glassy lithium ion conductor with the same composition as NASICON. The obtained glassy lithium ion conductor shows an ion conductivity equal to or higher than that of a sodium ion conductor, shows good stability to lithium metal, and is an excellent lithium ion solid electrolyte.

Drawings

FIG. 1 shows Na₃Si₂Zr₂PO₁₂And ionic liquid exchange L i₃Si₂Zr₂PO₁₂XRD pattern of (A), wherein, crystalline Na₃Si₂Zr₂PO₁₂Crystalline form L i after ion exchange₃Si₂Zr₂PO₁₂And L i retrograded at 600 and 800 DEG C₃Si₂Zr₂PO₁₂XRD spectrum of formation process, L i retrograded at 800 deg.C₃Si₂Zr₂PO₁₂Only the diffraction peak at 22 ℃ and ZrO are shown₂Impurity diffraction peaks.

Detailed Description

The invention is further illustrated by the following figures and examples.