High-performance composite solid electrolyte based on solid waste regenerated lithium source and preparation method thereof, and solid lithium battery

Abstract

The application discloses a kind of high-performance composite solid electrolyte based on solid waste regeneration lithium source and preparation method thereof.The composite solid electrolyte comprises sulfide electrolyte and halide electrolyte prepared from solid waste regeneration lithium source, and has core-shell structure or multilayer composite structure.The solid waste regeneration lithium source is lithium salt recovered and purified from electrolytic aluminum overhaul slag and / or electronic glass slag.The core-shell structure has sulfide electrolyte as inner core and halide electrolyte as outer shell, and the thickness of the outer shell is 1nm-500nm.The multilayer composite structure has a three-layer structure, including a first halide electrolyte layer, a sulfide electrolyte layer and a second halide electrolyte layer.The preparation method comprises the following steps: S1 raw material preparation, S2 sulfide electrolyte preparation, S3 halide electrolyte preparation and S4 composite construction.In the composite electrolyte, the sulfide component ensures bulk ion conductivity, the halide component provides stable interface with high-voltage positive electrode, and the electrochemical window is widened.

Description

Technical Field

[0001] This invention belongs to the field of solid-state lithium battery technology, and particularly relates to a high-performance composite solid electrolyte based on solid waste recycled lithium source, its preparation method, and solid-state lithium battery. Background Technology

[0002] With the development of new energy vehicles and energy storage systems, the demand for high-energy-density and high-safety solid-state lithium batteries is increasing. Solid-state lithium batteries use non-flammable solid electrolytes instead of liquid electrolytes, fundamentally improving safety. They are also compatible with lithium metal anodes and high-voltage cathodes, and are expected to achieve energy densities exceeding 400 Wh / kg. Among various solid electrolytes, sulfide electrolytes have become a research hotspot due to their high room-temperature ionic conductivity, low grain boundary resistance, and good mechanical ductility. However, their electrochemical stability window is narrow, and they are prone to oxidative decomposition when in contact with high-voltage cathode materials. Halide electrolytes, on the other hand, have a wide electrochemical window and good compatibility with high-voltage cathodes, but their ionic conductivity is relatively low, and their interfacial stability with lithium metal anodes is poor. Therefore, how to combine the high ionic conductivity of sulfide electrolytes with the high voltage stability of halide electrolytes to construct a composite solid-state electrolyte system is a technical problem that needs to be solved.

[0003] Currently, the preparation of solid electrolytes mainly relies on high-purity chemical raw materials, such as battery-grade lithium carbonate, high-purity lithium sulfide, and high-purity lithium chloride. The production cost of these raw materials is relatively high, and lithium resources mainly originate from salt lake brines and hard rock mines, with significant energy consumption during mining and purification processes. On the other hand, industrial solid wastes such as electrolytic aluminum overhaul slag and electronic glass slag contain lithium resources, but currently, most are disposed of through landfill or stockpiling, resulting in resource waste and environmental pressure.

[0004] To address the aforementioned issues, this invention proposes the preparation of a composite solid electrolyte using recycled lithium from industrial solid waste. Lithium sulfide is recovered from the slag of electrolytic aluminum overhaul, and lithium chloride and indium chloride are recovered from electronic glass slag. Sulfide electrolytes and halide electrolytes are prepared separately, and then combined using a core-shell structure or a multilayer composite structure. In this composite electrolyte, the sulfide component ensures the bulk ionic conductivity, while the halide component provides a stable interface with the high-voltage positive electrode, simultaneously inhibiting the oxidative decomposition of sulfides under high voltage. This method utilizes industrial solid waste to replace high-purity chemical raw materials, reducing the preparation cost of the solid electrolyte and providing a technical pathway for the utilization of lithium resources from industrial solid waste. Summary of the Invention

[0005] How to effectively suppress the interfacial side reactions between sulfides and high-voltage cathodes without sacrificing the high conductivity of sulfides, while simultaneously leveraging the interfacial protective effect of halides, remains a structural design challenge that has not yet been solved by existing technologies. Therefore, this invention provides a high-performance composite solid-state electrolyte based on recycled lithium from solid waste, its preparation method, and a solid-state lithium battery.

[0006] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0007] In a first aspect, the present invention provides a high-performance composite solid electrolyte based on a solid waste recycled lithium source, wherein the composite solid electrolyte comprises a sulfide electrolyte and a halide electrolyte prepared from a solid waste recycled lithium source.

[0008] The solid waste recycled lithium source is a lithium salt recovered and purified from electrolytic aluminum overhaul slag and / or electronic glass slag.

[0009] The composite solid electrolyte has a core-shell structure or a multilayer composite structure.

[0010] In one embodiment, the sulfide electrolyte includes silver-germanium sulfide type Li6PS5Cl and Li7P3S. 11 Or at least one of Thio-LISICON type sulfides;

[0011] The halide electrolyte includes lithium metal halides with high voltage stability.

[0012] In one embodiment, the core-shell structure is as follows: the core is a sulfide electrolyte, and the shell is a halide electrolyte; the thickness of the shell is 1 nm-500 nm.

[0013] In one embodiment, the multilayer composite structure is a stacked layered structure, including a first halide electrolyte layer, a sulfide electrolyte layer, and a second halide electrolyte layer, or an alternating stack of halide electrolyte layers and sulfide electrolyte layers.

[0014] In a second aspect, the present invention provides a method for preparing the composite solid electrolyte described in any one of the above claims, comprising the following steps:

[0015] S1 Raw material preparation: Provide high-purity lithium sulfide recovered from electrolytic aluminum overhaul slag, and high-purity lithium chloride and indium chloride recovered from electronic glass slag under an inert atmosphere;

[0016] S2 Sulfide electrolyte preparation: The regenerated lithium sulfide from step S1 is mixed with a sulfur source and a phosphorus source, and sulfide electrolyte powder is obtained by solid-phase reaction, high-energy ball milling or liquid-phase method.

[0017] S3 Preparation of halide electrolyte: The regenerated lithium chloride from step S1 is mixed with indium chloride, and halide electrolyte powder is obtained by solid-phase reaction, high-energy ball milling or liquid-phase method.

[0018] S4 Composite construction: The sulfide electrolyte from step S2 and the halide electrolyte from step S3 are combined to form a core-shell structured powder or a layered structured electrolyte membrane.

[0019] In one embodiment, when preparing a core-shell composite electrolyte, step S4 specifically includes: dispersing the sulfide electrolyte powder from step S2 in a solvent, adding a halide precursor solution prepared from the regenerated lithium source in step S1, and precipitating the halide electrolyte on the surface of the sulfide electrolyte and forming a coating layer by a solvothermal method; the solvothermal treatment temperature is 60-100℃ and the treatment time is 4-8 hours.

[0020] In one embodiment, when preparing a multilayer composite electrolyte membrane, step S4 specifically includes: using a multilayer casting method to sequentially form the halide electrolyte from step S3 and the sulfide electrolyte from step S2, and pressing each layer together using a hot pressing process; in the multilayer composite structure, the thickness of each halide electrolyte layer is 10-30 μm, and the thickness of each sulfide electrolyte layer is 30-50 μm.

[0021] In one embodiment, the entire preparation process is carried out in a strictly anhydrous and oxygen-free inert atmosphere to ensure the purity of the intermediate and final products.

[0022] Thirdly, the present invention provides a solid-state lithium battery, comprising a positive electrode, a negative electrode, and a solid electrolyte disposed between the positive electrode and the negative electrode, wherein the solid electrolyte comprises a composite solid electrolyte as described in any of the preceding claims, or a composite solid electrolyte prepared according to any of the preceding claims.

[0023] In one embodiment, the positive electrode comprises a high-voltage ternary cathode material, such as NCM811, NCM622, or NCA, and the negative electrode is metallic lithium or a lithium alloy.

[0024] Compared with the prior art, the present invention has at least the following beneficial effects:

[0025] The lithium resources in industrial solid wastes such as electrolytic aluminum overhaul slag and electronic glass slag are utilized in the preparation of solid electrolytes to reduce dependence on high-purity chemical raw materials, thereby reducing production costs and carbon emissions.

[0026] By employing core-shell or multi-layered composite structure designs, the contradiction between the high voltage intolerance of sulfide electrolytes and the low conductivity of halide electrolytes can be resolved. The sulfide component is located in the core or intermediate layer, ensuring high ionic conductivity in the bulk electrolyte phase; the halide component is located in the outer shell or surface layer, achieving stable interfacial contact with the high-voltage cathode and broadening the electrochemical window.

[0027] The halide shell or surface layer isolates the sulfide from direct contact with the cathode material, inhibiting the oxidative decomposition of the sulfide under high voltage; at the same time, the halide has a certain interface protection effect on the lithium metal anode, thereby improving the cycle life and coulombic efficiency of the all-solid-state battery. Attached Figure Description

[0028] Figure 1 The process flow diagram for preparing the core-shell structured composite electrolyte powder of this invention is shown. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Explanation of the source of recycled raw materials used in the examples:

[0031] 1. Regenerated lithium sulfide: derived from the slag of electrolytic aluminum overhaul, recovered through flotation-acid leaching-precipitation process, with a purity of ≥99.5%.

[0032] 2. Regenerated lithium chloride and indium chloride: derived from electronic glass slag, recovered through crushing-acid dissolution-extraction-crystallization process, with a purity of ≥99.5%.

[0033] All operations were performed in an argon-filled glove box (water and oxygen content < 0.1 ppm) or under strict inert atmosphere protection.

[0034] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0035] The embodiments of the present invention will now be described in detail with reference to specific examples and comparative examples.

[0036] Example 1: Preparation of core-shell structured composite electrolyte powder (Li6PS5Cl@Li3InCl6)

[0037] 1. Synthesis of sulfide kernels

[0038] Weigh out regenerated lithium sulfide (Li2S), regenerated phosphorus pentasulfide (P2S5), and lithium chloride (LiCl), and mix them in a molar ratio of 5:1:1 (corresponding to Li6PS5Cl). Place the mixture in a planetary ball mill and ball mill it at 500 rpm for 15 hours under an argon atmosphere to obtain Li6PS5Cl powder, a sulfide electrolyte of silver-germanium sulfide.

[0039] 2. Halogenated outer shell

[0040] 5g of the synthesized Li6PS5Cl powder was ultrasonically dispersed in 50mL of anhydrous ethanol to obtain a suspension. Separately, regenerated lithium chloride (LiCl) and regenerated indium chloride (InCl3) were dissolved in 20mL of anhydrous ethanol at a molar ratio of 3:1 to form a Li3InCl6 precursor solution. The precursor solution was slowly added dropwise to the sulfide suspension under vigorous stirring. After the addition was complete, the mixture was transferred to a reaction vessel and solvated at 80℃ for 6 hours. Then, it was vacuum dried at 60℃ for 12 hours to obtain a core-shell structured Li6PS5Cl@Li3InCl6 composite electrolyte powder.

[0041] 3. Performance Testing

[0042] The ionic conductivity of the powder was measured after compression into tablets, and was 2.1 mS / cm at room temperature. When assembled into a blocking electrode, the LSV (Liquid Sensitivity Variable) was measured, and the electrochemical window reached 4.6 V.

[0043] Example 2: Preparation of multilayer composite electrolyte membrane

[0044] 1. Halide layer slurry

[0045] Take 90 parts of the recycled Li3InCl6 powder synthesized in Example 1, add 10 parts of styrene-butadiene rubber (SBR) binder, disperse in xylene, and stir evenly.

[0046] 2. Sulfide layer slurry

[0047] Take 95 parts of the regenerated Li6PS5Cl powder synthesized in Example 1, add 5 parts of SBR binder, disperse in xylene, and stir evenly.

[0048] 3. Multilayer film forming

[0049] A three-layer co-casting method was adopted. First, a first layer of halide slurry was cast onto a PET release film with a thickness controlled at approximately 20 μm and dried at 50°C.

[0050] A sulfide slurry layer is cast onto the surface of the first layer, with a thickness controlled at approximately 40 μm, and then dried at 50°C.

[0051] A third layer of halide slurry is cast onto the surface of the intermediate layer, with a thickness controlled at approximately 20 μm, and then dried at 50°C.

[0052] The dried three-layer composite film was peeled off from the PET substrate and placed in a flatbed hot press. It was then hot-pressed at 60°C and 50MPa for 10 minutes to obtain a dense three-layer composite electrolyte film.

[0053] 4. Performance Testing

[0054] The room temperature ionic conductivity is 1.8 mS / cm. The membrane exhibits good flexibility and mechanical strength.

[0055] Example 3: Assembly and Testing of All-Solid-State Batteries

[0056] 1. Cathode preparation: Commercial NCM811 cathode material, Li6PS5Cl@Li3InCl6 electrolyte from Example 1, and conductive carbon black were mixed and ground at a mass ratio of 70:28:2 to form a composite cathode layer.

[0057] 2. Battery assembly: In the mold battery, a lithium foil negative electrode, a multilayer composite electrolyte membrane prepared in Example 2 (halide side facing the positive electrode), and a composite positive electrode layer are placed in sequence, and then pressed and shaped under a pressure of 200 MPa to assemble into a button cell or mold battery.

[0058] 3. Electrochemical Testing: Charge-discharge tests were conducted at room temperature with a current density of 0.1C. The initial discharge specific capacity was 198 mAh / g, with a coulombic efficiency of 89%. After 100 cycles, the capacity retention was 92%, demonstrating excellent cycle stability.

[0059] Comparative Example 1: Pure sulfide electrolyte

[0060] The regenerated Li6PS5Cl powder synthesized in Example 1 was used, but without halide coating, and directly pressed into sheets before battery assembly. Test results showed that its ionic conductivity was 3.0 mS / cm (slightly higher than that of the composite electrolyte), but after assembling into a Li|Li6PS5Cl|NCM811 battery, the initial coulombic efficiency was only 75%, and the capacity decayed to below 50% after 20 cycles. The electrochemical window was only 2.4V, confirming severe decomposition at high voltages.

[0061] Comparative Example 2: Physically Mixed Electrolytes

[0062] The regenerated Li6PS5Cl and regenerated Li3InCl6 powders synthesized in Example 1 were simply physically mixed at a mass ratio of 1:1, and then pressed into sheets to assemble batteries. Test results showed that the ionic conductivity decreased to 0.5 mS / cm, and the interfacial impedance was high, preventing the battery from charging and discharging normally. This indicates that simple physical mixing cannot form an effective ion transport network; a specific core-shell or multilayer structure is necessary to achieve synergistic performance.

[0063] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-performance composite solid electrolyte based on recycled lithium from solid waste, characterized in that, The composite solid electrolyte comprises a sulfide electrolyte and a halide electrolyte prepared from recycled lithium sources from solid waste. The solid waste recycled lithium source is a lithium salt recovered and purified from electrolytic aluminum overhaul slag and / or electronic glass slag. The composite solid electrolyte has a core-shell structure or a multilayer composite structure.

2. The high-performance composite solid electrolyte based on solid waste recycled lithium source according to claim 1, characterized in that, The sulfide electrolyte includes silver sulfide germanite type Li6PS5Cl and Li7P3S. 11 Or at least one of Thio-LISICON type sulfides; The halide electrolyte includes lithium metal halides with high voltage stability.

3. The high-performance composite solid electrolyte based on solid waste recycled lithium source according to claim 1, characterized in that, The core-shell structure is as follows: the core is a sulfide electrolyte, and the shell is a halide electrolyte; the thickness of the shell is 1nm-500nm.

4. The high-performance composite solid electrolyte based on solid waste recycled lithium source according to claim 1, characterized in that, The multilayer composite structure is a stacked structure, including a first halide electrolyte layer, a sulfide electrolyte layer, and a second halide electrolyte layer, or an alternating stack of halide electrolyte layers and sulfide electrolyte layers.

5. A method for preparing the composite solid electrolyte as described in any one of claims 1-4, characterized in that, Includes the following steps: S1 Raw material preparation: Provide high-purity lithium sulfide recovered from electrolytic aluminum overhaul slag, and high-purity lithium chloride and indium chloride recovered from electronic glass slag under an inert atmosphere; S2 Sulfide electrolyte preparation: The regenerated lithium sulfide from step S1 is mixed with a sulfur source and a phosphorus source, and sulfide electrolyte powder is obtained by solid-phase reaction, high-energy ball milling or liquid-phase method. S3 Preparation of halide electrolyte: The regenerated lithium chloride from step S1 is mixed with indium chloride, and halide electrolyte powder is obtained by solid-phase reaction, high-energy ball milling or liquid-phase method. S4 Composite construction: The sulfide electrolyte from step S2 and the halide electrolyte from step S3 are combined to form a core-shell structured powder or a layered structured electrolyte membrane.

6. The preparation method according to claim 5, characterized in that, When preparing a core-shell composite electrolyte, step S4 specifically includes: dispersing the sulfide electrolyte powder from step S2 in a solvent, adding the halide precursor solution prepared from the regenerated lithium source in step S1, and precipitating the halide electrolyte on the surface of the sulfide electrolyte and forming a coating layer by a solvothermal method; the solvothermal treatment temperature is 60-100℃ and the treatment time is 4-8 hours.

7. The preparation method according to claim 5, characterized in that, When preparing a multilayer composite electrolyte membrane, step S4 specifically includes: using a multilayer casting method, sequentially forming the halide electrolyte from step S3 and the sulfide electrolyte from step S2, and pressing each layer together using a hot pressing process; in the multilayer composite structure, the thickness of each halide electrolyte layer is 10-30 μm, and the thickness of each sulfide electrolyte layer is 30-50 μm.

8. The preparation method according to claim 5, characterized in that, The entire preparation process is carried out in a strictly anhydrous and oxygen-free inert atmosphere to ensure the purity of the intermediate and final products.

9. A solid-state lithium battery, comprising a positive electrode, a negative electrode, and a solid electrolyte disposed between the positive and negative electrodes, characterized in that, The solid electrolyte comprises the composite solid electrolyte according to any one of claims 1-4, or the composite solid electrolyte prepared by the method according to any one of claims 5-8.

10. The solid-state lithium battery according to claim 9, characterized in that, The positive electrode includes a high-voltage ternary cathode material, such as NCM811, NCM622 or NCA, and the negative electrode is metallic lithium or a lithium alloy.

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