Wide-temperature-range semi-solid electrolyte, lithium battery and preparation method thereof
By introducing Li6PS5Cl and a specific liquid solvent combination into lithium batteries, a wide-temperature-range semi-solid electrolyte was prepared, which solved the problem of performance degradation of lithium batteries at extreme temperatures and achieved high energy density and stable lithium battery performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA NORTH ENGINE RES INST
- Filing Date
- 2026-03-10
- Publication Date
- 2026-05-29
AI Technical Summary
Existing lithium battery electrolytes exhibit problems such as low conductivity at low temperatures, instability at high temperatures, interface film damage, and lithium dendrite nucleation under extreme high and low temperature environments, leading to a decline in battery performance. Furthermore, existing technologies have not effectively addressed the differences in charging and discharging methods between lithium-sulfur batteries and lithium batteries, making it impossible to utilize semi-solid electrolyte preparation methods.
Using Li6PS5Cl as the solid component, combined with fluorocarbonate, diethyl carbonate and ethylene sulfate as liquid solvents, and adding LiPF6 and LiFSI lithium salts, a semi-solid electrolyte membrane was prepared, and the electrolyte composition was optimized to adapt to wide temperature range operation.
It achieves high energy density and high and low temperature performance of lithium batteries in the temperature range of -50℃ to 50℃, improves the working stability and safety of batteries in extreme environments, and the energy density of soft pack batteries reaches 305Wh/kg.
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Figure CN122118045A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium-ion battery material preparation technology, specifically relating to a wide-temperature-range semi-solid electrolyte, a lithium battery, and a preparation method thereof. Background Technology
[0002] Under extreme high and low temperature environments, current power battery electrolytes have the following problems: 1) The main component of the electrolyte, LiPF6, does not dissociate sufficiently at low temperatures, resulting in low conductivity at low temperatures; LiPF6 has poor stability at high temperatures and is easily hydrolyzed to produce HF (electrode corrosion) and PF5 (catalytic solvent decomposition), leading to electrode surface corrosion and accelerating the destruction of the interface film; 2) The viscosity of the electrolyte increases sharply at low temperatures, and the electrolyte interface film on the negative electrode surface thickens or becomes denser at low temperatures, hindering the LiPF6 dissociation. + Migration leads to increased internal resistance and a sharp decrease in discharge capacity. At high temperatures, the interfacial film structure is prone to dissolution and recombination, losing its protective function and exacerbating interfacial side reactions, thus accelerating capacity decay. At low temperatures, the diffusion rate of lithium ions on the negative electrode surface decreases; at high temperatures, the migration rate of lithium ions increases. Both of these conditions can lead to uneven lithium deposition, exacerbating lithium dendrite nucleation and making it easier for lithium dendrites to penetrate the separator, causing a short circuit. The electrolyte mainly consists of lithium salts, organic solvents, and functional additives. Single-component solutions have narrow operating temperature ranges and limited performance, failing to meet the requirements of lithium-ion batteries. Therefore, multi-component mixed solvents are generally used.
[0003] Existing technologies have studied methods for preparing sulfide-based semi-solid lithium batteries, but have not covered methods for preparing electrolytes adaptable to high and low temperature environments for lithium batteries. Existing technologies have also studied methods for designing low-temperature electrolytes for lithium-sulfur batteries, but lithium-sulfur batteries and lithium batteries have different charging and discharging modes and cannot be used interchangeably. Furthermore, this research has not covered methods for preparing semi-solid electrolytes or research on high-temperature adaptability. Summary of the Invention
[0004] This invention provides a wide-temperature-range semi-solid electrolyte, a lithium battery, and a method for preparing the same, so as to ensure high energy density of the lithium battery while achieving operation over a wide temperature range.
[0005] To address the above technical problems, the present invention provides a wide-temperature-range semi-solid electrolyte, characterized in that it is composed of a solid component and a liquid solvent: The solid component is Li6PS5Cl; The liquid solvent comprises fluorocarbonate, diethyl carbonate, vinyl sulfate, and lithium salt dissolved therein; the lithium salt comprises LiPF6 and LiFSI.
[0006] Furthermore, the solid component accounts for 30% to 70% of the mass of the electrolyte.
[0007] Furthermore, based on the total mass of the liquid solvent, the mass percentage of each component is as follows: Fluorinated carbonates: 5% ~ 10%; Vinyl sulfate: 3% ~ 7%; The remainder is diethyl carbonate.
[0008] Furthermore, the concentration of the lithium salt in the liquid solvent is: LiPF6: 0.5 M ~ 2 M; LiFSI: 0.1 M ~ 0.3 M.
[0009] A method for preparing a wide-temperature-range semi-solid electrolyte, characterized by comprising the following steps: S1. Preparation of Li6PS5Cl solid powder: Li2S, P2S5 and LiClLi2 are dissolved in a mixed solution of tetrahydrofuran and ethanol at a predetermined molar ratio. The mixture is stirred and evaporated to obtain a solid mixture. Then, it is subjected to high-temperature heat treatment under an inert atmosphere and cooled to obtain Li6PS5Cl solid powder. S2. Preparation of liquid solvent: Fluorocarbonate, diethyl carbonate and vinyl sulfate are mixed in proportion, then LiPF6 and LiFSI are added and stirred until the lithium salt is completely dissolved to obtain a homogeneous liquid solvent. S3. Preparation of semi-solid electrolyte membrane: The Li6PS5Cl solid powder obtained in step S1 is mixed with the liquid solvent obtained in step S2 in a certain proportion, and after ultrasonic dispersion, it is polymerized under constant temperature to form a semi-solid electrolyte membrane.
[0010] Further, in step S1: The molar ratio of Li2S, P2S5 and LiCl is 6:3:1; The molar ratio of tetrahydrofuran to ethanol is 1:(2~4); The temperature of the stirred evaporation is above 50°C; The high-temperature heat treatment is performed at a temperature of 600℃ to 900℃, with a heating rate of 5℃ / min and a holding time of 2 to 7 hours.
[0011] Further, in step S3: The ultrasonic dispersion frequency is 20 kHz ~ 60 kHz, and the duration is greater than 30 minutes; The polymerization is carried out in a constant temperature chamber at a temperature of 60°C to 120°C for 12 to 24 hours.
[0012] A lithium battery, characterized in that it comprises: positive electrode; negative electrode; And a wide-temperature-range semi-solid electrolyte, or a wide-temperature-range semi-solid electrolyte prepared by the method.
[0013] Furthermore, the positive electrode is a ternary positive electrode, the active material of which is lithium cobalt oxide or lithium nickel cobalt manganese oxide, and contains conductive agents and binders, coated on aluminum foil or copper foil current collectors; The negative electrode is a silicon-carbon negative electrode, comprising a silicon-carbon composite material, a conductive agent, and a binder, coated on an aluminum foil or copper foil current collector.
[0014] A method for preparing a lithium battery, characterized in that the positive electrode is first formed by mixing aluminum cobalt oxide or manganese nickel cobalt oxide, a carbon conductive agent, and a polyvinylidene fluoride binder, and then coating it onto the surface of an aluminum foil or copper foil current collector; the negative electrode is first formed by mixing a silicon-carbon negative electrode, a carbon conductive agent, and a fluoroethylene binder, and then coating it onto the surface of an aluminum foil or copper foil current collector.
[0015] Beneficial effects: This invention selects a sulfide inorganic semi-solid electrolyte with high low-temperature conductivity and good high-temperature thermal stability, combined with a composite electrolyte solvent with high boiling point and low viscosity, thereby improving the working performance of lithium batteries in high and low temperature environments while ensuring high energy density.
[0016] 1) The wide-temperature-range electrolyte preparation method provided by this invention introduces sulfide solid components, high-boiling-point fluorocarbonate, low-viscosity diethyl carbonate and high-temperature stabilizer ethylene sulfate, and optimizes the composition of liquid solvent, which significantly improves the high and low temperature adaptability of lithium battery, enabling it to work in the temperature range of -50℃ to 50℃.
[0017] (2) The lithium battery preparation method provided by the present invention uses the above-mentioned wide temperature range semi-solid electrolyte, combined with ternary cathode and silicon-carbon anode, which can improve the energy density of lithium battery, and its soft pack battery energy density can reach 305Wh / kg. Attached Figure Description
[0018] Figure 1 Example 1: Charge-discharge curve at room temperature (25°C). Detailed Implementation
[0019] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below. Example 1:
[0020] 0.6 g Li₂S, 0.3 g P₂S₅, and 0.1 g LiCl were dissolved in a mixture of 10 mL 0.5 M tetrahydrofuran and 10 mL 1 M ethanol. The resulting mixture was vigorously stirred and evaporated at 60°C, and the solid product was collected. The solid product was subjected to high-temperature treatment in a tube furnace under an argon atmosphere, and the mixture was carbonized in a tube furnace under an argon atmosphere at 5 °C for 1 minute.‒1 The temperature was increased to 750 °C at a rate of [missing information], held at that temperature for 5 h, and then allowed to cool naturally to room temperature. Upon natural cooling to room temperature, Li6PS5Cl solid powder was obtained.
[0021] Mix 2g of fluorocarbonate, 17g of diethyl carbonate, and 1g of vinyl sulfate, then add 20 mmol of LiPF6 and 4 mmol of LiFSI to the mixture. Stir continuously until the lithium salt is completely dissolved to obtain a semi-solid electrolyte solvent. Mix 2g of Li6PS5Cl solid powder with 3g of solvent, and then use ultrasound to uniformly disperse the solid powder at a frequency of 40kHz for 40min. Polymerize in a constant temperature oven at 90℃ for 15h to obtain a semi-solid electrolyte membrane.
[0022] Manganese nickel cobalt oxide, carbon conductive agent, and polyvinylidene fluoride binder are mixed and then coated onto the surface of aluminum or copper foil current collectors to form the positive electrode of a lithium battery. A silicon-carbon negative electrode, carbon conductive agent, and fluorinated vinyl binder are mixed and then coated onto the surface of aluminum or copper foil current collectors to form the positive electrode of a lithium battery. The above semi-solid electrolyte is stacked with the positive and negative electrodes and combined with lithium battery manufacturing processes to produce a pouch battery. Figure 1 It can be calculated that the capacity of a single soft-pack battery cell is 14.8Ah, the discharge energy is 51.87Wh, and the weight of a single battery cell is 170g. The calculated 1C discharge energy density is 305Wh / kg.
[0023] Examples 2-5 and Comparative Examples 1-4 differ from Example 1 in that the composition of the solvent in the electrolyte or the mass percentage of Li6PS5Cl solid powder in the electrolyte is different. Otherwise, they are exactly the same as Example 1. The specific composition of the solvent in the electrolyte is shown in Table 1 below.
[0024] Table 1
[0025] Experimental Example: A lithium battery (170g) prepared using the examples and comparative examples was subjected to performance testing. The specific testing methods are as follows: Discharge performance test at room temperature (25℃): Charged at a constant current of 0.2C to 4.2V, then charged at a constant voltage of 4.2V until the current is less than 0.02C, left to stand for 30 minutes, and then discharged at 1C to 2.75V.
[0026] Low temperature (-50℃) discharge performance test: At room temperature and pressure, the battery is charged at 0.2C to 4.2V, then switched to constant voltage charging until the current is less than 0.02C; it is then transferred to a high and low temperature chamber, placed at -50℃ for 24h, and discharged at 0.5C to 2V.
[0027] High temperature (50℃) discharge performance test: At room temperature and pressure, the battery is charged at 0.2C to 4.2V, then switched to constant voltage charging until the current is less than 0.02C; it is then transferred to a high and low temperature chamber, placed at 50℃ for 16 hours, and discharged at 0.5C to 2.75V.
[0028] The test results are shown in Table 2 below.
[0029] Table 2
[0030] The test results above show that the mass ratio of Li6PS5Cl in the electrolyte and the composition of the electrolyte solvent significantly improve the battery capacity and its high and low temperature performance. The absence of one or more of fluorinated carbonates, ethylene sulfate, LiFSI, and Li6PS5Cl in the electrolyte reduces the battery capacity; the absence of one or two of fluorinated carbonates and ethylene sulfate increases the temperature rise during battery discharge, increasing safety hazards; and the absence of one or two of LiFSI and Li6PS5Cl reduces the low-temperature performance of the power battery. The above data sufficiently demonstrates that this invention, by adding fluorinated carbonates, ethylene sulfate, LiFSI, and Li6PS5Cl to the electrolyte solvent to construct a sulfide semi-solid electrolyte, significantly improves the capacity and high and low temperature performance of lithium-ion batteries.
[0031] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A wide-temperature-range semi-solid electrolyte, characterized in that, It consists of solid components and liquid solvent: The solid component is Li6PS5Cl; The liquid solvent comprises fluorocarbonate, diethyl carbonate, vinyl sulfate, and lithium salt dissolved therein; the lithium salt comprises LiPF6 and LiFSI.
2. The wide-temperature-range semi-solid electrolyte according to claim 1, characterized in that, The solid component accounts for 30% to 70% of the mass of the electrolyte.
3. The wide-temperature-range semi-solid electrolyte according to claim 1, characterized in that, Based on the total mass of the liquid solvent, the mass percentage of each component is as follows: Fluorinated carbonates: 5% ~ 10%; Vinyl sulfate: 3% ~ 7%; The remainder is diethyl carbonate.
4. The wide-temperature-range semi-solid electrolyte according to claim 1, characterized in that, The concentration of the lithium salt in the liquid solvent is: LiPF6: 0.5 M ~ 2 M; LiFSI: 0.1 M ~ 0.3 M.
5. A method for preparing a wide-temperature-range semi-solid electrolyte as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Preparation of Li6PS5Cl solid powder: Li2S, P2S5 and LiClLi2 are dissolved in a mixed solution of tetrahydrofuran and ethanol at a predetermined molar ratio. The mixture is stirred and evaporated to obtain a solid mixture. Then, it is subjected to high-temperature heat treatment under an inert atmosphere and cooled to obtain Li6PS5Cl solid powder. S2. Preparation of liquid solvent: Fluorocarbonate, diethyl carbonate and vinyl sulfate are mixed in proportion, and then LiPF6 and LiFSI are added. The mixture is stirred until the lithium salt is completely dissolved to obtain a homogeneous liquid solvent. S3. Preparation of semi-solid electrolyte membrane: The Li6PS5Cl solid powder obtained in step S1 is mixed with the liquid solvent obtained in step S2 in a certain proportion, and after ultrasonic dispersion, it is polymerized under constant temperature to form a semi-solid electrolyte membrane.
6. The method according to claim 5, characterized in that, In step S1: The molar ratio of Li2S, P2S5 and LiCl is 6:3:1; The molar ratio of tetrahydrofuran to ethanol is 1:(2~4); The temperature of the stirred evaporation is above 50°C; The high-temperature heat treatment is performed at a temperature of 600℃ to 900℃, with a heating rate of 5℃ / min and a holding time of 2 to 7 hours.
7. The method according to claim 5, characterized in that, In step S3: The ultrasonic dispersion frequency is 20 kHz ~ 60 kHz, and the duration is greater than 30 minutes; The polymerization is carried out in a constant temperature chamber at a temperature of 60°C to 120°C for 12 to 24 hours.
8. A lithium battery, characterized in that, Include: positive electrode; negative electrode; And a wide-temperature-range semi-solid electrolyte as described in any one of claims 1-4, or a wide-temperature-range semi-solid electrolyte prepared by the method described in any one of claims 5-7.
9. The lithium battery according to claim 8, characterized in that: The positive electrode is a ternary positive electrode, the active material of which is lithium cobalt oxide or lithium nickel cobalt manganese oxide, and contains conductive agent and binder, coated on aluminum foil or copper foil current collector. The negative electrode is a silicon-carbon negative electrode, comprising a silicon-carbon composite material, a conductive agent, and a binder, coated on an aluminum foil or copper foil current collector.
10. A method for preparing the lithium battery according to claim 8, characterized in that, The positive electrode is first formed by mixing aluminum cobalt oxide or manganese nickel cobalt oxide, carbon conductive agent, and polyvinylidene fluoride binder, and then coating it onto the surface of aluminum foil or copper foil current collector; the negative electrode is first formed by mixing silicon-carbon negative electrode, carbon conductive agent, and fluoroethylene binder, and then coating it onto the surface of aluminum foil or copper foil current collector.