Method for improving thermal safety of sulfide solid electrolyte
By introducing a polymer separator between the sulfide solid electrolyte and the cathode material, the exothermic reaction problem of the sulfide solid electrolyte under thermal abuse conditions is solved, significantly improving the safety of the battery.
Patent Information
- Application Number
- CN202511160966.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-19
- Publication Date
- 2025-11-28
AI Technical Summary
Sulfide solid electrolytes undergo violent exothermic reactions with cathode materials under thermal abuse conditions, posing a challenge to battery safety that is difficult to effectively address with existing technologies.
A polymer separator is introduced between the sulfide solid electrolyte and the cathode material. The separator is formed by heating and curing a mixture of polymer monomers, initiators and organic solvents to prevent oxygen crosstalk and reduce exothermic reactions.
This effectively reduces the exothermic reaction and harmful gas production between the cathode material and the sulfide solid electrolyte, thus improving the overall safety performance of the battery.
Smart Images
Figure CN121035367A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for improving the thermal safety of sulfide solid electrolytes, belonging to the field of solid electrolyte technology. Background Technology
[0002] Lithium-ion batteries are considered the most promising candidates for power batteries and energy storage due to their high energy density, long lifespan, low self-discharge rate, and clean, pollution-free operation. However, with increasingly stringent requirements for energy density and safety, traditional commercial liquid lithium-ion batteries are no longer sufficient. Solid-state lithium-ion batteries, with their higher theoretical energy density, high safety, wide operating temperature range, and lack of leakage issues, have gradually attracted researchers' attention. Furthermore, solid-state lithium-ion batteries are more environmentally friendly because they do not use toxic organic solvents.
[0003] Currently, common solid-state electrolytes mainly include oxide solid-state electrolytes, halide solid-state electrolytes, and sulfide solid-state electrolytes. Oxide solid-state electrolytes have low ionic conductivity and poor ductility at room temperature, making their preparation process complex and costly compared to other types of solid-state electrolytes. Although halide solid-state electrolytes have high ionic conductivity (≥1 mS / cm) and good oxidation stability, they contain high-valence metal cations, which readily react with the lithium anode, thus accelerating battery capacity decay. In contrast, sulfide solid-state electrolytes possess high ionic conductivity and good ductility, making them potential to become the mainstream solid-state electrolyte. However, research has found that under thermal abuse conditions, the main exothermic reaction leading to thermal runaway in sulfide all-solid-state batteries occurs between the cathode material and the sulfide solid-state electrolyte. On one hand, the sulfide solid-state electrolyte undergoes a violent exothermic reaction with oxygen released from the high-nickel cathode; on the other hand, exothermic reactions also occur between the directly contacting cathode and the sulfide solid-state electrolyte. This poses a significant challenge to improving the safety of all-solid-state batteries. Summary of the Invention
[0004] In view of this, the purpose of this invention is to provide a method for improving the thermal safety of sulfide solid electrolytes. This invention uses a thermosetting polymer to form a separator between the sulfide solid electrolyte and the battery positive electrode material, preventing direct contact between the two materials and preventing oxygen released from the positive electrode side under high-temperature conditions from interfering with the sulfide solid electrolyte. This reduces the intensity of the exothermic reaction between the sulfide solid electrolyte and the positive electrode material, thereby improving the overall safety performance of the battery.
[0005] To achieve the above objectives, the technical solution of the present invention is as follows.
[0006] A method for improving the thermal safety of sulfide solid electrolytes, comprising the following steps:
[0007] (1) Mix the polymer monomer, initiator and organic solvent evenly, heat and cure, and after curing, press into tablets to obtain polymer separators;
[0008] (2) In the process of assembling all-solid-state batteries, a polymer separator is placed between the sulfide solid electrolyte and the positive electrode to improve the thermal safety of the sulfide solid electrolyte.
[0009] Preferably, in step (1), the polymer monomer comprises unsaturated double-bonded monomers or cyclic monomers. More preferably, the polymer monomer comprises one or more of ether monomers, acrylate monomers, ethylene carbonate monomers, and acrylamide monomers. Most preferably, the ether monomer comprises one or more of 1,3-dioxolane, n-propane triglycidyl ether, polyethylene oxide, and tetrahydrofuran; the acrylate monomer comprises one or more of polymethacrylate, methyl methacrylate, polyethylene glycol diacrylate, pentaerythritol acrylates, and polyethylene glycol dimethacrylate; the ethylene carbonate monomer comprises vinylene carbonate and / or vinyl ethylene carbonate; and the acrylamide monomer comprises N,N'-methylenebisacrylamide and / or N,N'-dimethylacrylamide.
[0010] Preferably, in step (1), the initiator includes one or more of an azo initiator, a peroxide initiator, and a Lewis acid. More preferably, the azo initiator is azoisobutyronitrile (AIBN); the peroxide initiator is benzoyl peroxide; and the Lewis acid is one or more of boron trifluoride, phosphorus pentafluoride, and stannous octoate.
[0011] Preferably, in step (1), the organic solvent includes one or more of methyl ethyl carbonate, diethyl carbonate, fluoroethylene carbonate, propylene carbonate, ethylene carbonate, ethyl acetate, succinate, and adiponitrile.
[0012] Preferably, in step (1), the total mass of the polymer monomer, initiator, and organic solvent is 100%, the mass fraction of the polymer monomer is 0.1% to 50%, the mass fraction of the initiator is 0.1% to 10%, and the balance is the organic solvent. More preferably, the mass fraction of the polymer monomer is 2% to 40%, and the mass fraction of the initiator is 0.5% to 8%. Most preferably, the mass fraction of the polymer monomer is 5% to 10%, and the mass fraction of the initiator is 1% to 6%.
[0013] Preferably, in step (1), the curing temperature is 55-75℃ and the curing time is 6-48h.
[0014] Preferably, in step (2), the sulfide solid electrolyte is Li6PS5Cl or Li 10 GeP2S 12Li3PS4 or Li7P3S 11 .
[0015] Preferably, in step (2), the active material of the positive electrode is a nickel-cobalt-manganese ternary positive electrode material.
[0016] Preferably, in step (2), the thickness of the polymer separator is 1 / 3 to 1 / 2 of the thickness of the electrolyte.
[0017] Beneficial effects
[0018] The polymer separator mentioned in this invention prevents direct contact between the cathode material and the sulfide solid electrolyte, thus inhibiting solid-solid contact reactions between the electrolyte and the cathode material. Furthermore, the addition of the polymer separator significantly reduces gas production, effectively delaying or weakening the reaction between oxygen released during the cathode phase transition and the sulfide solid electrolyte. This method is simple and uses readily available raw materials. Attached Figure Description
[0019] Figure 1 The test results show the heat generation in the test examples and comparative examples.
[0020] Figure 2 The test results show the gas production in the test examples and comparative examples. Detailed Implementation
[0021] The present invention will be further described in detail below with reference to specific embodiments.
[0022] The present invention provides a polymer separator comprising the following raw materials: organic solvent, polymer monomer and initiator.
[0023] In this invention, the initiator in the raw materials is preferably 0.1-10% by mass, more preferably 0.5-8%, and most preferably 1-6% by mass; the polymer monomer in the raw materials is preferably 0.1-50% by mass, more preferably 2-40%, and most preferably 5-10%.
[0024] In this invention, the organic solvent is mainly the solvent used in lithium-ion battery electrolytes, preferably including one or more of methyl ethyl carbonate, diethyl carbonate, fluoroethylene carbonate, propylene carbonate, ethylene carbonate, ethyl acetate, succinate, and adiponitrile. When the organic solvent is two or more of the above-mentioned specific substances, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.
[0025] In this invention, the polymer monomer preferably comprises unsaturated double bonds or cyclic structures; the polymer monomer preferably comprises one or more of ether monomers, acrylate monomers, and acrylamide monomers; the ether monomer preferably comprises one or more of 1,3-dioxolane, n-propane triglycidyl ether, polyethylene oxide, and tetrahydrofuran; the acrylate monomer preferably comprises one or more of polymethacrylate, methyl methacrylate, polyethylene glycol diacrylate, pentaerythritol acrylates, and polyethylene glycol dimethacrylate; the ethylene carbonate monomer preferably comprises vinylene carbonate and / or vinyl ethylene carbonate; the acrylamide monomer preferably comprises N,N'-methylenebisacrylamide and / or N,N'-dimethylacrylamide; when the polymer monomer is two or more of the above-mentioned specific selections, this invention does not have any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio.
[0026] In this invention, the initiator includes one or more of azo initiators, peroxide initiators, and Lewis acids; the azo initiator is preferably azoisobutyronitrile (AIBN); the peroxide initiator is preferably benzoyl peroxide; and the Lewis acid is preferably boron trifluoride, phosphorus pentafluoride, and / or stannous octoate. When the initiator is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In this invention, when the polymer monomer is an acrylamide monomer or an acrylate monomer, the initiator is preferably azoisobutyronitrile; when the polymer monomer is an ether monomer, the initiator is preferably a Lewis acid initiator; and when the polymer monomer is a ethylene carbonate monomer, the initiator is preferably a Lewis acid or an azo initiator.
[0027] Example 1
[0028] Raw materials for preparation: The organic solvent is methyl ethyl carbonate; the polymer monomer is polyethylene glycol diacrylate, which accounts for 1% by mass in the raw materials; the initiator is AIBN, which accounts for 0.1% by mass in the raw materials.
[0029] After mixing the above raw materials evenly, place the mixed slurry in a 55-75℃ incubator for 8 hours. After it is completely cured, it can be collected and pressed into tablets to prepare polymer separators.
[0030] Example 2
[0031] Raw materials for preparation: The organic solvent is methyl ethyl carbonate; the polymer monomer is vinylene carbonate, with a mass percentage of 1% in the raw materials; the initiator is AIBN, with a mass percentage of 0.1% in the raw materials.
[0032] After mixing the above raw materials evenly, place the mixed slurry in a 55-75℃ incubator for 8 hours. After it is completely cured, it can be collected and pressed into tablets to prepare polymer separators.
[0033] Example 3
[0034] Raw materials for preparation: The organic solvent is methyl ethyl carbonate; the polymer monomer is N,N'-methylenebisacrylamide, which accounts for 1% by mass in the raw materials; the initiator is AIBN, which accounts for 0.1% by mass in the raw materials.
[0035] After mixing the above raw materials evenly, place the mixed slurry in a 55-75℃ incubator for 8 hours. After it is completely cured, it can be pressed into tablets to prepare the polymer separator.
[0036] Test case
[0037] The polymer separator prepared in Example 1 was mixed with a sulfide solid electrolyte and a high specific energy cathode material, wherein the mass ratio of polymer separator: sulfide solid electrolyte: cathode material = 1:3:6, to obtain a mixed material. The gas generation and heat generation characteristics of the mixed material were tested using a simultaneous integrated calorimeter-mass spectrometer (STA-MS).
[0038] Comparative Example
[0039] The sulfide solid electrolyte and the high specific energy cathode material were directly mixed in a mass ratio of sulfide solid electrolyte: cathode material = 1:2 to obtain a mixed material. The gas generation and heat generation characteristics of the mixed material were tested using a simultaneous integrated calorimeter-mass spectrometer (STA-MS).
[0040] The total sample mass of the above test examples and comparative examples is consistent. The sulfide solid electrolyte used is Li6PS5Cl, which was purchased from Ganfeng Lithium Corporation. The cathode material used is NCM811 (LiNi). 0.8 Co 0.1 Mn 0.1 O2).
[0041] according to Figure 1 It can be seen that the heat generation in the test case with the polymer separator is significantly reduced compared to the control group without the polymer separator, indicating that the presence of the polymer separator can effectively suppress the exothermic reaction between the cathode material and the sulfide solid electrolyte; in addition, according to Figure 2 It can be seen that the production of harmful SO2 gas during heating is also significantly reduced after the addition of the polymer separator.
[0042] The polymer separators in Examples 2-3 have similar effects as those in the test examples above when used between the sulfide solid electrolyte and the cathode material.
[0043] The comparison results above show that the safety improvement method provided by the present invention can significantly reduce the heat release and harmful gas production of the reaction between high specific energy cathode material and sulfide solid electrolyte, which is of great significance for improving the overall safety of the battery.
[0044] In summary, the invention includes, but is not limited to, the above embodiments. Any equivalent substitutions or partial improvements made under the spirit and principles of this invention shall be considered to be within the protection scope of this invention.
Claims
1. A method for improving the thermal safety of a sulfide solid electrolyte, characterized in that: The method steps include: (1) Mix the polymer monomer, initiator and organic solvent evenly, heat and cure, and after curing, press into tablets to obtain polymer separators; (2) In the process of assembling all-solid-state batteries, a polymer separator is placed between the sulfide solid electrolyte and the positive electrode to improve the thermal safety of the sulfide solid electrolyte.
2. The method for improving the thermal safety of a sulfide solid electrolyte as described in claim 1, characterized in that: In step (1), the polymer monomer includes unsaturated double bond monomers or cyclic monomers; the initiator includes one or more of azo initiators, peroxide initiators and Lewis acids.
3. The method for improving the thermal safety of a sulfide solid electrolyte as described in claim 2, characterized in that: The polymer monomers include one or more of ether monomers, acrylate monomers, ethylene carbonate monomers, and acrylamide monomers; The azo initiator is azoisobutyronitrile; the peroxide initiator is benzoyl peroxide; and the Lewis acid is one or more of boron trifluoride, phosphorus pentafluoride, and stannous octoate. The organic solvent includes one or more of methyl ethyl carbonate, diethyl carbonate, fluoroethylene carbonate, propylene carbonate, ethylene carbonate, ethyl acetate, succinate, and adiponitrile.
4. The method for improving the thermal safety of a sulfide solid electrolyte as described in claim 3, characterized in that: The ether monomers include one or more of 1,3-dioxolane, n-propane triglycidyl ether, polyethylene oxide, and tetrahydrofuran; the acrylate monomers include one or more of polymethacrylate, methyl methacrylate, polyethylene glycol diacrylate, pentaerythritol acrylates, and polyethylene glycol dimethacrylate; the ethylene carbonate monomers include vinylene carbonate and / or vinyl ethylene carbonate; and the acrylamide monomers include N,N'-methylenebisacrylamide and / or N,N'-dimethylacrylamide.
5. A method for improving the thermal safety of a sulfide solid electrolyte as described in any one of claims 1 to 4, characterized in that: The total mass of polymer monomers, initiators, and organic solvents is 100%, the mass fraction of the polymer monomers is 0.1% to 50%, the mass fraction of the initiator is 0.1% to 10%, and the balance is organic solvent.
6. The method for improving the thermal safety of a sulfide solid electrolyte as described in claim 5, characterized in that: The polymer monomer has a mass fraction of 2% to 40%, and the initiator has a mass fraction of 0.5% to 8%.
7. The method for improving the thermal safety of a sulfide solid electrolyte as described in claim 5, characterized in that: The polymer monomer has a mass fraction of 5% to 10%, and the initiator has a mass fraction of 1% to 6%.
8. The method for improving the thermal safety of a sulfide solid electrolyte as described in claim 1, characterized in that: In step (1), the curing temperature is 55-75℃ and the curing time is 6-48h.
9. The method for improving the thermal safety of a sulfide solid electrolyte as described in claim 1, characterized in that: In step (2), the sulfide solid electrolyte is Li6PS5Cl, Li 10 GeP2S 12 Li3PS4 or Li7P3S 11 ; The active material of the positive electrode is a nickel-cobalt-manganese ternary positive electrode material.
10. The method for improving the thermal safety of a sulfide solid electrolyte as described in claim 1, characterized in that: In step (2), the thickness of the polymer separator is 1 / 3 to 1 / 2 of the thickness of the electrolyte.