In-situ solidified electrolyte and preparation method thereof, solid-state battery and preparation method thereof

Abstract

The application provides an in-situ solidification electrolyte and a preparation method thereof, a solid-state battery and a preparation method thereof, and comprises a polymer monomer, an initiator, a lithium salt and an organic solvent, wherein the polymer monomer comprises a first polymer monomer and a second polymer monomer; the initiator is a solid-state electrolyte containing lithium carbonate or a solid-state electrolyte containing lithium hydroxide, and the mass of the lithium carbonate or the lithium hydroxide is 0.5-10 wt% of the mass of the solid-state electrolyte; the mass of the initiator is 1-8 wt% of the mass of the polymer monomer; and the sum of the mass of the polymer monomer and the mass of the initiator is 0.5-10 wt% of the total mass of the in-situ solidification electrolyte. Compared with the prior art, the electrolyte provided by the application uses the solid-state electrolyte containing lithium carbonate or the solid-state electrolyte containing lithium hydroxide as the initiator, and the initiator will not be left in the solid-state battery after in-situ polymerization of the polymer monomer in the solid-state battery, and will not cause the performance of the battery to deteriorate.

Description

Technical Field

[0001] This invention relates to the field of lithium batteries, specifically to an in-situ solidified electrolyte and its preparation method, and a solid-state battery and its preparation method. Background Technology

[0002] Lithium-ion batteries are currently widely used in digital products, power systems, and energy storage. However, commercially available lithium-ion batteries primarily use liquid electrolytes, which suffer from problems such as volatility, corrosion, flammability, explosiveness, and poor thermal stability. They are also prone to thermal runaway during use, leading to safety issues. Solid-state lithium-ion batteries, by using a solid electrolyte instead of liquid electrolytes, fundamentally solve these safety problems.

[0003] To improve the safety performance of lithium-ion batteries, a method for preparing in-situ solid-state batteries has been disclosed. This method uses electrolyte salts, organic solvents, vinyl monomers containing carbonate functional groups, and initiators as raw materials to prepare solid-state batteries in situ. This patent can improve the interfacial contact between the electrolyte and the positive and negative electrodes. However, the introduction of initiators can cause side reactions during battery charging and discharging.

[0004] In view of this, it is indeed necessary to provide a technical solution to the above problems. Summary of the Invention

[0005] One of the objectives of this invention is to provide an in-situ solidified electrolyte to solve the problem that the initiators used in current solid electrolytes remain in the battery, causing battery performance degradation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An in-situ curing electrolyte comprises a polymer monomer, an initiator, a lithium salt, and an organic solvent. The polymer monomer comprises a first polymer monomer and a second polymer monomer. The first polymer monomer is an alkenyl monomer containing an ester structure, and the second polymer monomer comprises at least one of a cycloalkane ether monomer and an olefin ether monomer. The initiator is a solid electrolyte containing lithium carbonate or a solid electrolyte containing lithium hydroxide, and the mass of the lithium carbonate or lithium hydroxide is 0.5–10 wt% of the mass of the solid electrolyte. The mass of the initiator is 1–8 wt% of the mass of the polymer monomer. The sum of the masses of the polymer monomer and the initiator is 0.5–10 wt% of the total mass of the in-situ curing electrolyte.

[0008] Preferably, the solid electrolyte is an oxide-type solid electrolyte or a sulfide-type solid electrolyte. Preferably, the oxide-type solid electrolyte is synthesized from lithium carbonate or lithium hydroxide with an oxide via a solid-phase reaction, and the sulfide-type solid electrolyte is synthesized from lithium carbonate or lithium hydroxide with a sulfide via a solid-phase reaction.

[0009] Preferably, the oxide-based solid electrolyte is one or more of perovskite-type electrolyte, inverse perovskite-type electrolyte, garnet-type electrolyte, NASICON-type electrolyte, and LISICON-type electrolyte; the sulfide-based solid electrolyte is a tin-containing sulfide-based solid electrolyte.

[0010] Preferably, the perovskite-type electrolyte is Li

[0012] ,

[0011] , , La 2 / 3-x TiO3, 0.02 < x < 0.25; the inverse perovskite-type electrolyte is Li 3-y (OH y )Cl, Li 3-y (OH y )Br, and Li 3-y (OH y )I, at least one of which, where 0.8 < y < 2; the garnet-type electrolyte is a doped or undoped lithium lanthanum zirconium oxide electrolyte, and the doping element is selected from at least one of Al, Ga, Fe, Ge, Ca, Ba, Sr, Y, Nb, Ta, W, and Sb elements; the NASICON-type electrolyte is Li 1+a Ti 2-a M a (PO4)3, Li 1+a Ge 2-a M a (PO4)3, at least one of which, 0.1 ≤ a ≤ 0.6, M = at least one of Al, Cr, Ga, Fe, Sc, In, Lu, Y, and La; the LISICON-type electrolyte is Li 4-b Ge 1-b P b S4, 0.2 < b < 0.8; the tin-containing sulfide-based solid electrolyte is Li 4-c Sn 1-c A c S4, A = at least one of As, Sb, Bi, and P, where 0 ≤ c ≤ 0.5.

[0011] Preferably, the ester-containing alkenyl monomers include at least one of vinyl carbonate, ethylene vinyl sulfite, vinylene trithiocarbonate, 1,3-propylene sulfonate, ethyl propylene carbonate, formic acid diester, allyl phenyl carbonate, methyl methacrylate, and vinyl acetate; the cycloalkane ether monomers include at least one of ethylene oxide, 1,2-epoxypropane, tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, and 1,4-dioxane; the olefin ether monomers include at least one of polyethylene glycol methyl ether methacrylate and polyethylene glycol methyl ether acrylate.

[0012] Preferably, the lithium salt is one or a combination of any two or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium chloride, lithium iodide, lithium tri(pentafluoroethyl)trifluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, lithium tetrafluorooxalate phosphate, lithium carbonate, and lithium fluoride, and the mass of the lithium salt is 2-15 wt% of the total mass of the in-situ cured electrolyte; the organic solvent is at least one of acetonitrile, tetrahydrofuran, acetone, methylpyrrolidone, N,N-dimethyldiamide, ethyl acetate, sulfolane, ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, and dimethyl carbonate, and the mass of the organic solvent is 70-90 wt% of the total mass of the in-situ cured electrolyte.

[0013] The second objective of this invention is to provide a method for preparing an in-situ solidified electrolyte, comprising the following steps:

[0014] S1. An oxide-type solid electrolyte or a sulfide-type solid electrolyte is prepared using lithium carbonate or lithium hydroxide as raw materials. The resulting solid electrolyte also contains 0.5 to 10 wt% lithium carbonate or lithium hydroxide as an initiator.

[0015] S2. The initiator obtained in step S1 is added to an organic solvent and mixed together with the polymer monomer and lithium salt to obtain an in-situ cured electrolyte; wherein, the mass of the initiator is 1 to 8 wt% of the mass of the polymer monomer; the sum of the mass of the polymer monomer and the initiator is 0.5 to 10 wt% of the total mass of the in-situ cured electrolyte.

[0016] A third objective of this invention is to provide a solid-state battery, comprising a casing and a positive electrode, a negative electrode, and a gel electrolyte spaced between the positive electrode and the negative electrode, wherein the gel electrolyte is obtained by initiating the in-situ solidified electrolyte described in any of the above-mentioned embodiments in a solid-state battery at 30–90°C for 1–10 hours.

[0017] The fourth objective of this invention is to provide a method for preparing the solid-state battery described above, comprising the following steps:

[0018] S1. An oxide-type solid electrolyte or a sulfide-type solid electrolyte is prepared using lithium carbonate or lithium hydroxide as raw materials. The resulting solid electrolyte also contains 0.5 to 10 wt% lithium carbonate or lithium hydroxide as an initiator.

[0019] S2. The initiator obtained in step S1 is added to an organic solvent and mixed together with the polymer monomer and lithium salt to obtain an in-situ cured electrolyte; wherein, the mass of the initiator is 1 to 8 wt% of the mass of the polymer monomer; the sum of the mass of the polymer monomer and the initiator is 0.5 to 10 wt% of the total mass of the in-situ cured electrolyte;

[0020] S3. Assemble the in-situ solidified electrolyte obtained in step S2 with the positive and negative electrode sheets into the casing, and bake it at 30-90°C for 1-10 hours to obtain a solid-state battery containing gel electrolyte.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The electrolyte provided by the present invention uses a solid electrolyte containing lithium carbonate or a solid electrolyte containing lithium hydroxide as an initiator. After in-situ initiation and participation in polymer monomer polymerization in the solid battery, it will not remain in the solid battery and will not cause performance degradation of the battery. At the same time, the solid electrolyte used can further improve the ionic conductivity of the gel electrolyte, thereby improving the electrochemical performance of the solid battery. Detailed Implementation

[0022] 1. In-situ solidified electrolyte

[0023] The first aspect of this invention aims to provide an in-situ curing electrolyte, comprising a polymer monomer, an initiator, a lithium salt, and an organic solvent, wherein the polymer monomer comprises a first polymer monomer and a second polymer monomer, the first polymer monomer being an alkenyl monomer containing an ester structure, and the second polymer monomer comprising at least one of a cycloalkane ether monomer and an olefin ether monomer; the initiator is a solid electrolyte containing lithium carbonate or a solid electrolyte containing lithium hydroxide, and the mass of the lithium carbonate or lithium hydroxide is 0.5 to 10 wt% of the mass of the solid electrolyte; the mass of the initiator is 1 to 8 wt% of the mass of the polymer monomer; and the sum of the masses of the polymer monomer and the initiator is 0.5 to 10 wt% of the total mass of the in-situ curing electrolyte.

[0024] The in-situ solidified electrolyte provided by this invention uses a lithium carbonate-containing solid electrolyte or a lithium hydroxide-containing solid electrolyte as an initiator. The lithium carbonate and lithium hydroxide act as Lewis bases, participating in the ring-opening reaction of cycloalkane ether monomers and the polymerization reaction containing unsaturated bonds in an electrolyte containing polymer monomers. This achieves the purpose of initiating polymer monomer polymerization and realizing the effect of in-situ solidification. After lithium carbonate or lithium hydroxide participates in the reaction, it does not remain in the solid-state battery and generate side reactions, nor does it cause deterioration of battery performance. Compared with existing solid-state electrolytes and solid-state batteries, the in-situ solidified electrolyte provided by this invention and the solid-state battery using it have better electrochemical stability and safety.

[0025] That is, an inorganic solid electrolyte with excess lithium is used as an initiator, and the semi-solid electrolyte (i.e., gel electrolyte) after polymerization does not contain initiator residue.

[0026] Specifically, the mass of the lithium carbonate or lithium hydroxide can be 0.5–1 wt%, 2–3 wt%, 3–4 wt%, 4–5 wt%, 5–6 wt%, 6–7 wt%, 7–8 wt%, 8–9 wt%, or 9–10 wt% of the solid electrolyte. Preferably, the mass of the lithium carbonate or lithium hydroxide can be 2–7 wt% of the solid electrolyte, and more preferably, the mass of the lithium carbonate or lithium hydroxide can be 5 wt% of the solid electrolyte. By mixing an excess of lithium carbonate or lithium hydroxide within the above range with the solid electrolyte, its initiating effect can precisely initiate and participate in the polymerization reaction of the polymer monomers, thereby further improving the ionic conductivity of the gel while ensuring the electrochemical performance of the battery.

[0027] The sum of the mass of the polymer monomer and the initiator can be 0.5–2 wt%, 2–3 wt%, 3–4 wt%, 4–5 wt%, 5–6 wt%, 6–7 wt%, 7–8 wt%, 8–9 wt%, or 9–10 wt% of the total mass of the in-situ curing electrolyte. Preferably, the sum of the mass of the polymer monomer and the initiator can be 3–8 wt% of the total mass of the in-situ curing electrolyte.

[0028] The initiator may be 1-2 wt%, 2-3 wt%, 3-4 wt%, 4-5 wt%, 5-6 wt%, 6-7 wt%, or 7-8 wt% of the polymer monomer. Preferably, the initiator may be 3-7 wt% of the polymer monomer.

[0029] Preferably, the mass of the first polymer monomer is 55-85 wt% of the total mass of the polymer monomers; and the mass of the second polymer monomer is 15-45 wt% of the total mass of the polymer monomers. More preferably, the mass of the first polymer monomer is 65-80 wt% of the total mass of the polymer monomers; and the mass of the second polymer monomer is 20-35 wt% of the total mass of the polymer monomers.

[0030] In some embodiments, the solid electrolyte is an oxide-type solid electrolyte, which is synthesized by reacting lithium carbonate or lithium hydroxide with an oxide in a solid phase.

[0031] In some embodiments, the solid electrolyte is a sulfide-type solid electrolyte, which is synthesized by reacting lithium carbonate or lithium hydroxide with a sulfide in a solid phase. The sulfide referred to herein can be a mixture of sulfur monomers and metal oxides to obtain the sulfide-type solid electrolyte.

[0032] Using inorganic solid electrolytes such as oxide-type or sulfide-type solid electrolytes offers better compatibility with lithium carbonate or lithium hydroxide. Furthermore, lithium carbonate or lithium hydroxide can be used as a raw material in the synthesis of solid electrolytes. Thus, during the synthesis of solid electrolytes, an excess of lithium carbonate or lithium hydroxide can be added. A portion of the lithium carbonate or lithium hydroxide undergoes a solid-phase reaction to synthesize the oxide-type or sulfide-type solid electrolyte, while the remaining lithium carbonate or lithium hydroxide remains in the resulting solid electrolyte, acting as an initiator along with the solid electrolyte. This results in a more uniform mixture, excellent compatibility, and a simpler preparation process. For example, if 100% lithium carbonate or lithium hydroxide is added, 90–99.5% will be used to synthesize the solid electrolyte, while the remaining 0.5–10 wt% will remain unreacted, forming an excess that acts as an initiator along with the generated solid electrolyte.

[0033] In some embodiments, the oxide-type solid electrolyte is one or more of perovskite-type electrolyte, anti-perovskite-type electrolyte, garnet-type electrolyte, NASICON-type electrolyte, and LISICON-type electrolyte; the sulfide-type solid electrolyte is a tin-containing sulfide-type solid electrolyte.

[0034] Specifically, in some embodiments, the perovskite electrolyte is Li 3x La 2 / 3-x TiO3, 0.02 <x<0.25。

[0035] In some embodiments, the anti-perovskite electrolyte is Li 3-y (OH y Cl, Li 3-y (OH y )Br and Li 3-y (OH y At least one of I, wherein 0.8 <y<2。

[0036] In some embodiments, the garnet-type electrolyte is a doped or undoped lithium lanthanum zirconium oxide electrolyte, wherein the doping element is selected from at least one of Al, Ga, Fe, Ge, Ca, Ba, Sr, Y, Nb, Ta, W, and Sb; preferably, the garnet-type electrolyte is Li7La3Zr2O. 12 (LLZO), Li 7-z La3Zr 2-z Ta z O 12 (0≤z≤0.8), Li 7-z La3Zr 2-z Nb z O 12(0≤z≤0.8) and Li 7-z La3Zr 2-z Al z O 12 At least one of (0≤z≤0.8).

[0037] In some embodiments, the NASICON-type electrolyte is Li 1+a Ti 2-a M a (PO4)3, Li 1+a Ge 2-a M a At least one of (PO4)3, 0.1 ≤ a ≤ 0.6, M = at least one of Al, Cr, Ga, Fe, Sc, In, Lu, Y, La; preferably, the NASICON type electrolyte is Li 1+a Ti 2-a Al a (PO4)3(LATP), Li 1+a Ge 2-a Al a (PO4)3(LAGP), 0.1≤a≤0.6.

[0038] In some embodiments, the LISICON type electrolyte Li 4-b Ge 1-b P b S4, 0.2 <b<0.8。

[0039] In some embodiments, the tin-containing sulfide-type solid electrolyte is Li 4-c Sn 1-c A c S4, A = at least one of As, Sb, Bi, P, where 0 ≤ c ≤ 0.5.

[0040] In some embodiments, the ester-containing alkenyl monomers include at least one of vinyl carbonate, vinyl sulfite, trithiovinyl carbonate, 1,3-propenyl-sulfonyl lactone, ethyl propylene carbonate, formate, allyl phenyl carbonate, methyl methacrylate, and vinyl acetate; the cycloalkane ether monomers include at least one of ethylene oxide, 1,2-epoxypropane, tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, and 1,4-dioxane; and the olefin ether monomers include at least one of polyethylene glycol methyl ether methacrylate and polyethylene glycol methyl ether acrylate.

[0041] In some embodiments, the lithium salt is one or any combination of two or more of the following: lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethyl)sulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium chloride (LiCl), lithium iodide (LiI), lithium tris(pentafluoroethyl)trifluorophosphate, lithium dioxalate borate (LiBOB), lithium difluorooxalate borate (LiDFOB), lithium difluorodioxalate phosphate (LiDFOP), lithium tetrafluorooxalate phosphate (LiTFOP), lithium carbonate (LiCO3), and lithium fluoride (LiF). The mass of the lithium salt is 2 to 15 wt% of the total mass of the in-situ solidified electrolyte.

[0042] In some embodiments, the organic solvent is at least one selected from acetonitrile, tetrahydrofuran, acetone, methylpyrrolidone, N,N-dimethyldiamide, ethyl acetate, sulfolane, ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, and dimethyl carbonate, and the mass of the organic solvent is 70-90 wt% of the total mass of the in-situ cured electrolyte.

[0043] Furthermore, the in-situ solid electrolyte of the present invention may also contain additives, which may be conventional electrolyte additives, including but not limited to at least one of film-forming additives, conductive additives, flame-retardant additives, overcharge prevention additives, additives for controlling the H2O and HF content in the electrolyte, additives for improving low-temperature performance, and multifunctional additives. Specifically, it may include PS, EP, CN, etc., with a mass percentage of 0–7.5 wt%. Preferably, the sum of the mass of the lithium salt and the additives is 15–20 wt% of the total mass of the in-situ solidified electrolyte.

[0044] A second aspect of this invention aims to provide a method for preparing the in-situ solidified electrolyte, comprising the following steps:

[0045] S1. An oxide-type solid electrolyte or a sulfide-type solid electrolyte is prepared using lithium carbonate or lithium hydroxide as raw materials. The resulting solid electrolyte also contains 0.5 to 10 wt% lithium carbonate or lithium hydroxide as an initiator.

[0046] S2. The initiator obtained in step S1 is added to an organic solvent and mixed together with the polymer monomer and lithium salt to obtain an in-situ cured electrolyte; wherein, the mass of the solid electrolyte is 0.01 to 0.5 wt% of the mass of the polymer monomer; and the sum of the masses of the polymer monomer and the initiator is 0.5 to 10 wt% of the total mass of the in-situ cured electrolyte.

[0047] It should be noted that the in-situ solidified electrolyte obtained by the above preparation method is a liquid electrolyte that has not yet undergone initiation. After being assembled into the battery, it undergoes heating and initiation to form a gel electrolyte in situ. Compared with conventional liquid electrolytes, this gel electrolyte can fundamentally solve the safety issues of lithium-ion batteries while ensuring the electrochemical performance of lithium-ion batteries.

[0048] 2. Solid-state batteries

[0049] A third aspect of the present invention aims to provide a solid-state battery, comprising a housing and a positive electrode, a negative electrode, and a gel electrolyte spaced between the positive electrode and the negative electrode, the positive electrode being obtained by initiating the in-situ solidified electrolyte as described in any of the preceding claims in a solid-state battery at 30–90°C for 1–10 h.

[0050] The active material layer coated on the positive electrode can be, but is not limited to, a chemical formula such as Li. a Ni x Co y M z O 2-b N b (where 0.95≤a≤1.2, x>0, y≥0, z≥0, and x+y+z=1, 0≤b≤1, M is selected from one or more combinations of Mn and Al, and N is selected from one or more combinations of F, P, and S) The positive electrode active material may also be, but is not limited to, LiCoO2, LiNiO2, LiVO2, LiCrO2, LiMn2O4, LiCoMnO4, Li2NiMn3O8, LiNi 0.5 Mn 1.5 The positive electrode active material can be one or more combinations of O4, LiCoPO4, LiMnPO4, LiFePO4, LiNiPO4, LiCoFSO4, CuS2, FeS2, MoS2, NiS, and TiS2. The positive electrode active material can also be modified. Methods for modifying the positive electrode active material are known to those skilled in the art. For example, coating, doping, and other methods can be used to modify the positive electrode active material. The materials used for modification can be one or more combinations of Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, and W, including but not limited to. The positive electrode current collector used in the positive electrode sheet is typically a structure or component that collects current. The positive electrode current collector can be any material suitable for use as a positive electrode current collector in lithium-ion batteries. For example, the positive electrode current collector can be, but is not limited to, metal foil, and more specifically, aluminum foil, among others.

[0051] The active material layer coated on the negative electrode sheet can be one or more of the following: graphite, soft carbon, hard carbon, carbon fiber, mesophase carbon microspheres, silicon-based materials, tin-based materials, lithium titanate, or other metals that can form alloys with lithium. Specifically, the graphite can be selected from one or more of artificial graphite, natural graphite, and modified graphite; the silicon-based material can be selected from one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, and silicon alloys; and the tin-based material can be selected from one or more of elemental tin, tin oxide compounds, and tin alloys. The negative electrode current collector used in the negative electrode sheet is typically a structure or component that collects current. This current collector can be any material suitable for use as a negative electrode current collector in lithium-ion batteries, for example, it can be, but is not limited to, metal foil, and more specifically, copper foil.

[0052] A fourth aspect of the present invention aims to provide a method for preparing the solid-state battery, comprising the following steps:

[0053] S1. An oxide-type solid electrolyte or a sulfide-type solid electrolyte is prepared using lithium carbonate or lithium hydroxide as raw materials. The resulting solid electrolyte also contains 0.5 to 10 wt% lithium carbonate or lithium hydroxide as an initiator.

[0054] S2. The initiator obtained in step S1 is added to an organic solvent and mixed together with the polymer monomer and lithium salt to obtain an in-situ cured electrolyte; wherein, the mass of the solid electrolyte is 0.01 to 0.5 wt% of the mass of the polymer monomer; the sum of the mass of the polymer monomer and the initiator is 0.5 to 10 wt% of the total mass of the in-situ cured electrolyte;

[0055] S3. Assemble the in-situ solidified electrolyte obtained in step S2 with the positive and negative electrode sheets into the casing, and bake it at 30-90°C for 1-10 hours to obtain a solid-state battery containing gel electrolyte.

[0056] To make the technical solution and advantages of the present invention clearer, the present invention and its beneficial effects will be described in further detail below in conjunction with specific embodiments, but the embodiments of the present invention are not limited thereto.

[0057] Example 1

[0058] An in-situ curing electrolyte comprises a polymer monomer, an initiator, a lithium salt, and an organic solvent. The polymer monomer comprises a first polymer monomer and a second polymer monomer. The first polymer monomer is an alkenyl monomer containing an ester structure, and the second polymer monomer comprises at least one of a cycloalkane ether monomer and an olefin ether monomer. The initiator is a solid electrolyte containing lithium carbonate or a solid electrolyte containing lithium hydroxide, and the mass of the lithium carbonate or lithium hydroxide is 0.5–10 wt% of the mass of the solid electrolyte. The mass of the initiator is 1–8 wt% of the mass of the polymer monomer. The sum of the masses of the polymer monomer and the initiator is 0.5–10 wt% of the total mass of the in-situ curing electrolyte.

[0059] Specifically, the polymer monomers are ethyl propylene carbonate and polyethylene glycol methyl ether acrylate; the initiator is a 5wt% Li2CO3 excess Li4SnS4 sulfide solid electrolyte.

[0060] The preparation method of this in-situ solidified electrolyte includes the following steps:

[0061] S1. Mix 1.5g Li2CO3, 1.02g SnO2, and 5g S, and ball mill for 12h to form a homogeneous mixture; place the resulting mixture in an argon atmosphere and calcine at a heating rate of 5℃ / min at 700℃ for 12h, then cool to obtain a Li4SnS4 sulfide solid electrolyte containing 5wt% excess Li2CO3, which serves as an initiator;

[0062] S2. Mix the initiator with ethyl propylene carbonate and polyethylene glycol methyl ether acrylate, with ethyl propylene carbonate accounting for 75%, polyethylene glycol methyl ether acrylate accounting for 20%, and Li4SnS4 accounting for 5% by percentage.

[0063] S3. Add the mixture obtained in step S2 to the EC / DMC electrolyte containing 1M LiPF6, wherein the mixture in step S2 accounts for 5%, the lithium salt and additives account for 20%, and the organic solvent accounts for 75%, to obtain the in-situ solidified electrolyte.

[0064] The in-situ solidified electrolyte obtained above is applied to solid-state batteries.

[0065] A solid-state battery includes a casing and a positive electrode, a negative electrode, and a gel electrolyte spaced between the positive and negative electrodes, all contained within the casing. The gel electrolyte is obtained by initiating the aforementioned in-situ solidified electrolyte in a solid-state battery at 60°C for 5 hours. The positive electrode uses lithium cobalt oxide as the positive active material, and the negative electrode uses lithium metal as the negative active material. Specific preparation methods for both are detailed in existing positive and negative electrode preparation methods and will not be elaborated here.

[0066] The specific preparation method is as follows: the above-mentioned in-situ solidified electrolyte is injected into the shell containing positive and negative electrode sheets, and then placed in an oven at 60°C for 5 hours to obtain a solid-state battery containing gel electrolyte.

[0067] Example 2

[0068] Unlike Example 1, the initiator in this example is a LATP oxide-type solid electrolyte containing 5 wt% excess LiOH; the preparation method is to ball-mill LiOH and LATP for 10 h to obtain a LATP oxide-type solid electrolyte with excess LiOH.

[0069] The rest is the same as in Example 1, and will not be repeated here.

[0070] Example 3

[0071] Unlike Example 1, the initiator in this example is an LLZO oxide-type solid electrolyte containing 5 wt% excess Li2CO3; the preparation method is to ball-mill Li2CO3 and LLZO for 10 h to obtain an LLZO oxide-type solid electrolyte with excess Li2CO3.

[0072] The rest is the same as in Example 1, and will not be repeated here.

[0073] Example 4

[0074] Unlike Example 1, the initiator in this example is Li containing 5 wt% Li₂CO₃ in excess. 3.8 Sn 0.8 As 0.2 S4; The preparation method is to add As2O3 and mix them together during the solid-phase synthesis process.

[0075] The rest is the same as in Example 1, and will not be repeated here.

[0076] Example 5

[0077] Unlike Example 1, the initiator in this example is a Li4SnS4 sulfide solid electrolyte containing 0.5wt% Li2CO3 in excess.

[0078] The rest is the same as in Example 1, and will not be repeated here.

[0079] Example 6

[0080] Unlike Example 1, the initiator in this example is a Li4SnS4 sulfide solid electrolyte containing 2wt% Li2CO3 in excess.

[0081] The rest is the same as in Example 1, and will not be repeated here.

[0082] Example 7

[0083] Unlike Example 1, the initiator in this example is a Li4SnS4 sulfide solid electrolyte containing 10wt% Li2CO3 in excess.

[0084] The rest is the same as in Example 1, and will not be repeated here.

[0085] Example 8

[0086] Unlike Example 1, the initiator in this example is an LLZO oxide-type solid electrolyte containing 0.5 wt% Li2CO3 in excess.

[0087] The rest is the same as in Example 1, and will not be repeated here.

[0088] Example 9

[0089] Unlike Example 1, the initiator in this example is an LLZO oxide-type solid electrolyte containing 2wt% excess Li2CO3.

[0090] The rest is the same as in Example 1, and will not be repeated here.

[0091] Example 10

[0092] Unlike Example 1, the initiator in this example is an LLZO oxide-type solid electrolyte containing 10 wt% Li2CO3 in excess.

[0093] The rest is the same as in Example 1, and will not be repeated here.

[0094] Example 11

[0095] Unlike Example 1, in step S2 above, the proportion of the initiator after mixing with ethyl propylene carbonate and polyethylene glycol methyl ether acrylate is 1%, and the proportion of ethyl propylene carbonate is 79%.

[0096] The rest is the same as in Example 1, and will not be repeated here.

[0097] Example 12

[0098] Unlike Example 1, in step S2 above, the proportion of the initiator after mixing with ethyl propylene carbonate and polyethylene glycol methyl ether acrylate is 8%, and the proportion of ethyl propylene carbonate is 72%.

[0099] The rest is the same as in Example 1, and will not be repeated here.

[0100] Example 13

[0101] Unlike Example 1, the polymer monomers in this example are formate diester and 1,2-epoxypropane, wherein the formate diester accounts for 75%, the 1,2-epoxypropane accounts for 20%, and the initiator accounts for 5%.

[0102] The rest is the same as in Example 1, and will not be repeated here.

[0103] Example 14

[0104] Unlike Example 1, the polymer monomers in this example are formate diester and 1,2-epoxypropane, wherein the formate diester accounts for 72%, the 1,2-epoxypropane accounts for 20%, and the initiator accounts for 8%.

[0105] The rest is the same as in Example 1, and will not be repeated here.

[0106] Example 15

[0107] Unlike Example 1, the polymer monomers in this example are ethyl propylene carbonate and 1,2-epoxypropane, wherein ethyl propylene carbonate accounts for 75%, 1,2-epoxypropane accounts for 20%, and the initiator accounts for 5%.

[0108] The rest is the same as in Example 1, and will not be repeated here.

[0109] Example 16

[0110] Unlike Example 1, the content of polymer monomers is as follows: ethyl propylene carbonate accounts for 20%, and polyethylene glycol methyl ether acrylate accounts for 75%.

[0111] The rest is the same as in Example 1, and will not be repeated here.

[0112] Example 17

[0113] The difference from Example 13 is the content of polymer monomers: formate accounts for 20% and 1,2-epoxypropane accounts for 75%.

[0114] The rest is the same as in Example 13, and will not be repeated here.

[0115] Example 18

[0116] Unlike Example 1, in the solid-state battery preparation, the initiator was cured at 80°C for 3 hours to obtain a gel electrolyte.

[0117] The rest is the same as in Example 1, and will not be repeated here.

[0118] Example 19

[0119] Unlike Example 1, in the solid-state battery preparation, the initiator curing conditions were changed to 40°C for 8 hours to obtain a gel electrolyte.

[0120] The rest is the same as in Example 1, and will not be repeated here.

[0121] Example 20

[0122] Unlike Example 13, in the solid-state battery preparation, the initiator curing conditions were changed to initiation at 80°C for 3 hours to obtain a gel electrolyte.

[0123] The rest is the same as in Example 13, and will not be repeated here.

[0124] Example 21

[0125] Unlike Example 13, in the solid-state battery preparation, the initiator curing conditions were changed to 40°C for 8 hours to obtain a gel electrolyte.

[0126] The rest is the same as in Example 13, and will not be repeated here.

[0127] Example 22

[0128] Unlike Example 1, the lithium salt composition in the in-situ cured electrolyte is different. In this example, the lithium salt is a mixture of LiPF6 and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), with LiPF6 accounting for 95% and LiTFSI accounting for 5%.

[0129] The rest is the same as in Example 1, and will not be repeated here.

[0130] The solid-state batteries obtained in Examples 1 to 22 above were subjected to cycle performance tests at 1C / 1C and 2.75 to 4.2V.

[0131] The test results are shown in Table 1 below.

[0132] Table 1

[0133]

[0134]

[0135] The test results above show that the gel electrolyte obtained by in-situ initiation using the in-situ solidified electrolyte provided by this invention effectively improves the cycle capacity retention of solid-state batteries containing this gel electrolyte, and it still maintains a relatively good capacity retention even after long-term cycling. This is mainly because the in-situ solidified electrolyte provided by this invention uses a solid electrolyte containing lithium carbonate or a solid electrolyte containing lithium hydroxide as an initiator. This initiator can effectively initiate and participate in the polymerization reaction of the polymer monomers of this invention, and the gel electrolyte will not remain in the solid-state battery after being obtained, thus effectively avoiding the problem of battery electrochemical performance deterioration caused by initiator residue. At the same time, the added solid electrolyte can also improve the ionic conductivity, thereby further improving the cycle performance of the solid-state battery.

[0136] The comparison of Examples 1-4 shows that the solid electrolyte containing excess lithium carbonate or lithium hydroxide obtained through solid-phase synthesis with the participation of lithium carbonate or lithium hydroxide exhibits superior electrochemical performance compared to the method of directly mixing lithium carbonate or lithium hydroxide with the solid electrolyte. This is mainly because the excess lithium carbonate or lithium hydroxide reserved through synthesis results in a more uniform mixture with the solid electrolyte, leading to a more significant initiation effect. Furthermore, the comparison of Examples 1, 3, 5-7, 8-10, and 11-12 also shows that the excess content of lithium carbonate or lithium hydroxide affects the cycle performance of the solid-state battery. Preferably, a 5 wt% excess yields a solid-state battery with better cycle performance. Additionally, the comparison of Examples 1, 13, and 18-21 shows that the solid-state conditions of the initiator also affect the cycle performance of the solid-state battery. A solid-state battery with better cycle performance is obtained when the curing temperature is 60°C and the initiation time is 5 hours.

[0137] Furthermore, the comparison of Examples 1, 13-17 also shows that the selection and content of polymer monomers also affect the cycle performance of solid-state batteries. In particular, when the proportion of the first polymer monomer is larger than that of the second polymer monomer, the solid-state battery exhibits superior cycle performance.

[0138] In summary, the in-situ solidified electrolyte and the resulting solid-state battery provided by this invention effectively solve the problem that the initiator used in current solid-state electrolytes will remain in the battery, causing battery performance degradation.

[0139] Based on the disclosure and teachings of the foregoing specification, those skilled in the art can make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments described above, and any obvious improvements, substitutions, or modifications made by those skilled in the art based on the present invention are within the scope of protection of the present invention. Furthermore, although some specific terms are used in this specification, these terms are only for convenience of explanation and do not constitute any limitation on the present invention.

Claims

1. An in-situ solidified electrolyte, characterized in that, The electrolyte comprises polymer monomers, an initiator, a lithium salt, and an organic solvent. The polymer monomers include a first polymer monomer and a second polymer monomer. The first polymer monomer is an alkenyl monomer containing an ester structure, and the second polymer monomer includes at least one of cycloalkane ether monomers and olefin ether monomers. The initiator is a solid electrolyte containing lithium carbonate or lithium hydroxide. The solid electrolyte is an oxide-type solid electrolyte or a sulfide-type solid electrolyte prepared using lithium carbonate or lithium hydroxide as raw materials, and the mass of the lithium carbonate or lithium hydroxide is 0.5–10 wt% of the mass of the solid electrolyte. The mass of the initiator is 1–8 wt% of the mass of the polymer monomers. The sum of the masses of the polymer monomers and the initiator is 0.5–10 wt% of the total mass of the in-situ cured electrolyte.

2. The in-situ solidified electrolyte according to claim 1, characterized in that, The oxide-type solid electrolyte is synthesized by reacting lithium carbonate or lithium hydroxide with an oxide in a solid phase, and the sulfide-type solid electrolyte is synthesized by reacting lithium carbonate or lithium hydroxide with a sulfide in a solid phase.

3. The in-situ solidified electrolyte according to claim 2, characterized in that, The oxide-type solid electrolyte is one or more of the following: perovskite-type electrolyte, anti-perovskite-type electrolyte, garnet-type electrolyte, NASICON-type electrolyte, and LISICON-type electrolyte; the sulfide-type solid electrolyte is a tin-containing sulfide-type solid electrolyte.

4. The in-situ solidified electrolyte according to claim 3, characterized in that, The perovskite-type electrolyte is Li 3x La 2 / 3-x TiO3, where 0.02 < x < 0.25; the inverse perovskite-type electrolyte is Li 3-y (OH y )Cl, Li 3-y (OH y )Br, and at least one of Li 3-y (OH y )I, where 0.8 < y < 2; the garnet-type electrolyte is a doped or undoped lithium lanthanum zirconium oxide electrolyte, and the doping element is selected from at least one of the elements Al, Ga, Fe, Ge, Ca, Ba, Sr, Y, Nb, Ta, W, Sb; the NASICON-type electrolyte is Li 1+a Ti 2-a M a (PO4)3, Li 1+a Ge 2-a M a (PO4)3, where 0.1 ≤ a ≤ 0.6, and M = at least one of Al, Cr, Ga, Fe, Sc, In, Lu, Y, La; the LISICON-type electrolyte Li 4-b Ge 1-b P b S4, where 0.2 < b < 0.8; the tin-containing sulfide-type solid electrolyte is Li 4-c Sn 1-c A c S4, where A = at least one of As, Sb, Bi, P, and 0 ≤ c ≤ 0.

5.

5. The in-situ solidified electrolyte according to claim 1, characterized in that, The ester-containing alkenyl monomers include at least one of vinyl carbonate, vinyl sulfite, trithiovinyl carbonate, 1,3-propenyl-sulfonyl lactone, ethyl propylene carbonate, formate, allyl phenyl carbonate, methyl methacrylate, and vinyl acetate; the cycloalkane ether monomers include at least one of ethylene oxide, 1,2-epoxypropane, tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, and 1,4-dioxane; and the olefin ether monomers include at least one of polyethylene glycol methyl ether methacrylate and polyethylene glycol methyl ether acrylate.

6. The in-situ solidified electrolyte according to claim 1, characterized in that, The lithium salt is one or a combination of any two or more of the following: lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium chloride, lithium iodide, lithium tri(pentafluoroethyl)trifluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, lithium tetrafluorooxalate phosphate, lithium carbonate, and lithium fluoride. The mass of the lithium salt is 2-15 wt% of the total mass of the in-situ cured electrolyte. The organic solvent is at least one of the following: acetonitrile, tetrahydrofuran, acetone, methylpyrrolidone, N,N-dimethyldiamide, ethyl acetate, sulfolane, ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, and dimethyl carbonate. The mass of the organic solvent is 70-90 wt% of the total mass of the in-situ cured electrolyte.

7. A method for preparing an in-situ solidified electrolyte, characterized in that, Includes the following steps: S1. An oxide-type solid electrolyte or a sulfide-type solid electrolyte is prepared using lithium carbonate or lithium hydroxide as raw materials. The resulting solid electrolyte also contains 0.5 to 10 wt% lithium carbonate or lithium hydroxide as an initiator. S2. The initiator obtained in step S1 is added to an organic solvent and mixed together with the polymer monomer and lithium salt to obtain an in-situ cured electrolyte; wherein, the mass of the initiator is 1 to 8 wt% of the mass of the polymer monomer; the sum of the mass of the polymer monomer and the initiator is 0.5 to 10 wt% of the total mass of the in-situ cured electrolyte; the polymer monomer includes a first polymer monomer and a second polymer monomer, the first polymer monomer is an alkenyl monomer containing an ester structure, and the second polymer monomer includes at least one of cycloalkane ether monomers and olefin ether monomers.

8. A solid-state battery, characterized in that, The device includes a housing and a positive electrode, a negative electrode, and a gel electrolyte spaced between the positive electrode and the negative electrode, wherein the gel electrolyte is obtained by initiating the in-situ solidified electrolyte according to any one of claims 1 to 6 in a solid-state battery at 30 to 90°C for 1 to 10 hours.

9. A method for preparing a solid-state battery according to claim 8, characterized in that, Includes the following steps: S1. An oxide-type solid electrolyte or a sulfide-type solid electrolyte is prepared using lithium carbonate or lithium hydroxide as raw materials. The resulting solid electrolyte also contains 0.5 to 10 wt% lithium carbonate or lithium hydroxide as an initiator. S2. The initiator obtained in step S1 is added to an organic solvent and mixed together with the polymer monomer and lithium salt to obtain an in-situ cured electrolyte; wherein, the mass of the initiator is 1 to 8 wt% of the mass of the polymer monomer; the sum of the mass of the polymer monomer and the initiator is 0.5 to 10 wt% of the total mass of the in-situ cured electrolyte; the polymer monomer includes a first polymer monomer and a second polymer monomer, the first polymer monomer is an alkenyl monomer containing an ester structure, and the second polymer monomer includes at least one of cycloalkane ether monomers and olefin ether monomers; S3. Assemble the in-situ solidified electrolyte obtained in step S2 with the positive and negative electrode sheets into the casing, and bake it at 30-90°C for 1-10 hours to obtain a solid-state battery containing gel electrolyte.

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