Solid-state electrolyte, solid-state battery and preparation method and application thereof

Abstract

The invention discloses a solid electrolyte, a solid-state battery and a preparation method and application thereof, and belongs to the technical field of solid-state batteries. The chemical formula of the solid electrolyte provided by the invention is Li < 2 + x > In < 2-x > / 3Cl4, and x is greater than or equal to 0 and less than or equal to 2. The ionic conductivity and the electrochemical performance of the solid electrolyte are improved mainly by optimizing the sintering temperature and the sintering time. According to the method, the transmission path of lithium ions in the solid electrolyte can be shortened, the energy density of the solid-state lithium ion battery is remarkably improved, and meanwhile, the solid-state lithium ion battery has relatively good cycling stability.

Description

Technical Field

[0001] The present application belongs to the field of solid-state battery technology, and in particular relates to a solid-state electrolyte, a solid-state battery, and a preparation method and application thereof. Background Art

[0002] With the rapid development of demand for electric vehicles and various electronic consumer products, traditional lithium-ion batteries can no longer meet market demand due to their low energy density and safety issues. Therefore, it is urgent to develop rechargeable batteries with high specific energy, long cycle and high safety. All-solid-state lithium batteries have attracted great interest due to their advantages such as higher safety stability and greater energy density compared to lithium-ion batteries. Among them, solid electrolytes are one of the key materials for realizing all-solid-state lithium batteries. Compared with existing oxide, sulfide and polymer solid electrolytes, halide solid electrolytes have become one of the research hotspots in recent years due to their advantages such as non-toxicity, high ionic conductivity, high voltage stability, wide electrochemical stability window and good deformability. However, their high preparation cost and poor stability to lithium metal on the negative electrode side limit the practical application of halide solid electrolytes. Therefore, it is urgent to find low-cost and better-performing halide solid electrolytes and apply them to all-solid-state lithium-ion batteries. Summary of the invention

[0003] In order to solve the above technical problems, the present application provides a solid electrolyte, a solid-state battery, and a preparation method and application thereof. Through high-energy ball milling and high-temperature sintering methods, a halide solid electrolyte with high ionic conductivity is prepared and an all-solid-state battery is assembled, thereby improving the energy density of the solid-state battery and promoting its commercial development.

[0004] In order to achieve the above-mentioned invention object, this application provides the following technical solutions:

[0005] On the one hand, the present application provides a solid electrolyte, the chemical formula of the solid electrolyte is Li 2+x In (2-x) / 3Cl4, where 0≤x≤2.

[0006] Optionally, the value of x is independently selected from any value among 0, 0.5, 1, 1.5, 2, or a range of values ​​between any two of the above points.

[0007] Optionally, the ionic conductivity of the solid electrolyte is 0.6 to 1.6 mS / cm.

[0008] Optionally, the ionic conductivity of the solid electrolyte is independently selected from any value among 0.6 mS / cm, 1.0 mS / cm, 1.2 mS / cm, 1.6 mS / cm, or a range between any two of the above points.

[0009] In a second aspect, the present application provides a method for preparing the above-mentioned solid electrolyte, comprising the following steps:

[0010] The mixture containing LiCl and InCl3 is ground, cold pressed and sintered in sequence to obtain the solid electrolyte.

[0011] Optionally, the molar ratio of the Li element, the In element and the Cl element in the mixture is 2-4:0-1:4.

[0012] Optionally, the grinding speed is 300-500 r / min;

[0013] The grinding time is 15 to 25 hours.

[0014] Optionally, the grinding rotation speed is independently selected from any value among 300r / min, 350r / min, 400r / min, 450r / min, 500r / min or a range value between any two of the above points.

[0015] Optionally, the grinding time is independently selected from any value among 15h, 17h, 20h, 22h, 25h or a range value between any two of the above points.

[0016] Optionally, the grinding further includes a pre-grinding step.

[0017] Optionally, the rotation speed of the pre-grinding is 100 to 300 r / min;

[0018] The pre-grinding time is 1 to 2 hours.

[0019] Optionally, the rotation speed of the pre-grinding is independently selected from any value among 100r / min, 150r / min, 200r / min, 250r / min, 300r / min or a range between any two of the above points.

[0020] Optionally, the pre-grinding time is independently selected from any value among 1 h, 1.2 h, 1.5 h, 2 h, or a range between any two of the above points.

[0021] Optionally, the sintering temperature is 200-500°C;

[0022] The sintering time is 3 to 9 hours.

[0023] Optionally, the sintering temperature is independently selected from any value of 200° C., 300° C., 400° C., 500° C. or a range between any two of the above points.

[0024] Optionally, the sintering time is independently selected from any value among 3h, 5h, 7h, 9h or a range between any two of the above points.

[0025] Optionally, the sintering is performed in an inert gas atmosphere;

[0026] The inert gas atmosphere is selected from at least one of nitrogen, helium and argon.

[0027] In a third aspect, the present application provides a solid-state battery, comprising a positive electrode, a negative electrode and a solid-state electrolyte.

[0028] Optionally, the solid electrolyte is selected from the above-mentioned solid electrolytes.

[0029] Optionally, the positive electrode is selected from LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi 0.9 Co 0.05 Mn 0.05 At least one of O2 and LiCoO2.

[0030] Optionally, the negative electrode is selected from at least one of Li-In alloy, Li-Mg alloy, Li-Sn alloy and Li.

[0031] In a fourth aspect, the present application provides a method for preparing the above-mentioned solid-state battery, comprising the following steps:

[0032] The solid electrolyte, positive electrode and negative electrode are respectively compressed and assembled to obtain the solid-state battery.

[0033] Preferably, the method for preparing the solid-state battery comprises the following steps:

[0034] A solid electrolyte with a mass of 90 to 110 mg is placed in a battery mold and pressed at a pressure of 400 to 550 MPa for 1 to 3 minutes. The positive electrode is pressed at a pressure of 400 to 550 MPa for 1 to 3 minutes. The cut negative electrode is placed at the bottom of the battery mold and pressed at a pressure of 20 to 50 MPa for 1 to 3 minutes. The solid-state battery is assembled.

[0035] Compared with the prior art, this application has the following beneficial effects:

[0036] (1) The solid electrolyte Li provided in this application 2+x In (2-x) / 3 Cl4(0≤x≤2) has high ionic conductivity and excellent electrochemical properties.

[0037] (2) The preparation method of the solid electrolyte provided in this application is simple and effective, mainly by optimizing the sintering temperature and sintering time to improve the Li 2+x In (2-x) / 3The ionic conductivity and electrochemical properties of Cl4 (0≤x≤2) are good, and the method provided in the present application can shorten the transmission path of lithium ions in the solid electrolyte, reduce grain boundary restrictions, reduce lithium ion transmission impedance, significantly improve the energy density of solid-state lithium-ion batteries, and have good cycle stability.

[0038] (3) The solid-state battery provided by the present application can be stably cycled at 35°C and obtain a high discharge capacity; the present application forms a stable phase interface between a solid electrolyte mainly composed of LiCl and a negative electrode in the solid battery, which effectively inhibits dendrite growth and improves electrochemical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 This is an impedance curve diagram of the solid electrolyte at different sintering temperatures and sintering times in Example 1 of the present application;

[0041] Figure 2 The impedance curve of the solid electrolyte in this application is when the molar ratio of LiCl: InCl3 is 3:1, at the optimal sintering temperature and the optimal sintering time;

[0042] Figure 3 This is a cycle performance diagram of the all-solid-state lithium battery of Example 2 of the present application;

[0043] Figure 4 This is a long cycle performance diagram of the all-solid-state lithium battery of Example 4 of the present application. DETAILED DESCRIPTION

[0044] The present application is further described below in conjunction with specific embodiments. The following are only a few embodiments of the present application, and are not intended to limit the present application in any form. Although the present application discloses the following preferred embodiments, they are not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the above disclosed technical content to make some changes or modifications are equivalent to equivalent implementation cases and are within the scope of the technical solution.

[0045] Unless otherwise specified, the raw materials in the examples of the present application were purchased from commercial sources and used directly without any special treatment.

[0046] Unless otherwise specified, the analysis methods in the examples all adopt conventional settings and conventional analysis methods of instruments or equipment.

[0047] Example 1

[0048] 3.6505g LiCl and 6.3495g InCl3 with a molar ratio of 3:1 were placed in a ball mill, and an amorphous phase mixture of a halide solid electrolyte was obtained by pre-milling at 100r / min for 1h, ball milling at 300r / min for 2h, and ball milling at 500r / min for 20h. The blank was then cold-pressed to obtain a green embryo, which was placed in a quartz tube and heated to 200℃, 300℃, 400℃ and 500℃ at room temperature for 5h, respectively, with a heating rate of 1℃ / min. The temperature was cooled to room temperature to obtain a ceramic phase halide solid electrolyte. Comparison showed that the ionic conductivity of the solid electrolyte was optimal when the sintering temperature was 300℃. The cold-pressed green embryo was then placed in a quartz tube, heated to 300℃ at room temperature for 3h, 5h, 7h and 9h, respectively, with a heating rate of 1℃ / min. The temperature was cooled to room temperature to obtain a ceramic phase halide solid electrolyte. Comparison showed that the ionic conductivity of the solid electrolyte was optimal when the sintering time was 7h. It can be seen that the solid electrolyte obtained at a sintering temperature of 300°C, a sintering time of 7h, and a heating rate of 1°C / min has the optimal ionic conductivity.

[0049] Example 2

[0050] 3.6505g LiCl and 6.3495g InCl3 with a molar ratio of 3:1 were placed in a ball mill, and the amorphous phase mixture of halide solid electrolyte was obtained by pre-milling at 100r / min for 1h, 300r / min for 2h, and 500r / min for 20h. Then, the blank was obtained by cold pressing, and placed in a quartz tube. It was heated to 300℃ at room temperature for 7h, with a heating rate of 1℃ / min, and the temperature was lowered to room temperature to obtain a ceramic phase halide solid electrolyte. With Li-In as the negative electrode, NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2) is the positive electrode, with a loading of 8.15 mg / cm 2 , at 0.147 mA cm -2 The battery cycle test was carried out at 35°C with a current density of 1.5 %. The test showed that the battery cycled 60 times and the capacity remained at 188 mAh g -1 .

[0051] Example 3

[0052] 3.6505g LiCl and 6.3495g InCl3 with a molar ratio of 3:1 were placed in a ball mill, and the amorphous phase mixture of the halide solid electrolyte was obtained by pre-milling at 100r / min for 1h, 300r / min for 2h, and 500r / min for 20h. Then, the blank was obtained by cold pressing, and placed in a quartz tube. It was heated to 300℃ at room temperature for 7h, with a heating rate of 1℃ / min, and the temperature was lowered to room temperature to obtain a ceramic phase halide solid electrolyte. Li-In was used as the negative electrode, and Ni90 (LiNi 0.9 Co 0.05 Mn 0.05 O2) is the positive electrode, with a loading of 8.15 mg / cm 2 , at 0.733 mA·cm -2 The battery cycle test was carried out at 35°C with a current density of 1.5 %. The battery cycled 290 times and the capacity remained at 148 mAh g -1 .

[0053] Example 4

[0054] 3.6505g LiCl and 6.3495g InCl3 with a molar ratio of 3:1 were placed in a ball mill, and the amorphous phase mixture of halide solid electrolyte was obtained by pre-milling at 100r / min for 1h, 300r / min for 2h, and 500r / min for 20h. Then, the blank was cold pressed and placed in a quartz tube. The blank was heated to 300℃ for 7h at room temperature with a heating rate of 1℃ / min. The temperature was lowered to room temperature to obtain a ceramic phase halide solid electrolyte. Li-In was used as the negative electrode, LCO (LiCoO2) was used as the positive electrode, and the loading was 8.15mg / cm 2 , at 0.733 mA cm -2 The battery cycle test was carried out at 35°C with a current density of 1.5 %. The battery cycled 390 times and the capacity remained at 130 mAh g -1 .

[0055] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A solid electrolyte, characterized in that The chemical formula of the solid electrolyte is Li 2+x In (2-x) / 3 Cl4, where 0≤x≤2.

2. A solid electrolyte according to claim 1, characterized in that: The ionic conductivity of the solid electrolyte is 0.6-1.6 mS / cm.

3. A method for preparing a solid electrolyte according to claim 1 or 2, characterized in that: The steps include: The mixture containing LiCl and InCl3 is ground, cold pressed and sintered in sequence to obtain the solid electrolyte.

4. The method for preparing a solid electrolyte according to claim 3, characterized in that: The molar ratio of the Li element, the In element and the Cl element in the mixture is 2-4:0-1:

4.

5. The method for preparing a solid electrolyte according to claim 3, characterized in that: The grinding speed is 300-500 r / min; The grinding time is 15 to 25 hours.

6. The method for preparing a solid electrolyte according to claim 3, characterized in that: The grinding also includes a pre-grinding step; Preferably, the speed of the pre-grinding is 100-300 r / min; The pre-grinding time is 1 to 2 hours.

7. The method for preparing a solid electrolyte according to claim 3, characterized in that: The sintering temperature is 200-500°C; The sintering time is 3 to 9 hours.

8. The method for preparing a solid electrolyte according to claim 3, characterized in that: The sintering is carried out in an inert gas atmosphere; The inert gas atmosphere is selected from at least one of nitrogen, helium and argon.

9. A solid-state battery, characterized in that: The solid-state battery comprises a positive electrode, a negative electrode and a solid electrolyte; The solid electrolyte is selected from the solid electrolyte according to claim 1 or 2; Preferably, the positive electrode is selected from LiNi 0.8 Co 0.1 Mn 0.1 O2、LiNi 0.9 Co 0.05 Mn 0.05 At least one of O2 and LiCoO2; Preferably, the negative electrode is selected from at least one of Li-In alloy, Li-Mg alloy, Li-Sn alloy and Li.

10. The method for preparing a solid-state battery according to claim 9, characterized in that: The steps include: The solid electrolyte, positive electrode and negative electrode according to claim 1 or 2 are compressed separately and then assembled to obtain the solid-state battery.

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