Composite solid electrolyte, semi-solid electrolyte, and semi-solid battery

Abstract

The application relates to the technical field of batteries, in particular to a composite solid-state electrolyte, a semi-solid-state electrolyte and a semi-solid-state battery. The composite solid-state electrolyte comprises a solid-state electrolyte and an acetylsulfamic acid compound; the mass content of the acetylsulfamic acid compound in the composite solid-state electrolyte is not less than 0.5%. The composite solid-state electrolyte can improve the long cycle stability, high power performance and interface durability of the semi-solid-state battery.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a composite solid electrolyte, a semi-solid electrolyte, and a semi-solid battery. Background Technology

[0002] In recent years, with the rapid development of new energy vehicles in China, people's requirements for the driving range and charging time of new energy vehicles have been increasing. This places higher demands on the energy density, power performance, and safety of lithium-ion batteries, which has driven research into higher energy density lithium-ion battery technologies. Among these technologies, semi-solid-state battery technology can meet consumers' needs for long driving range and safety, and is also more similar to conventional lithium-ion batteries, with universal production equipment. Semi-solid-state batteries typically use binary / ternary cathode materials with higher specific capacity, and the anode uses graphite, graphite-doped silicon, graphite-doped silicon-carbon, or graphite-doped silicon-oxygen, giving semi-solid-state batteries higher energy density.

[0003] While semi-solid-state batteries achieve higher energy density by using binary / ternary cathode materials and silicon-containing anodes, the overall cycle stability of the cell and the stability of the materials are affected. This is because as the binary / ternary cathode materials and silicon-containing materials cycle, the particles repeatedly expand and contract until they break, which leads to continuous side reactions between the positive and negative electrodes and the electrolyte, consuming active lithium and increasing interfacial impedance. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides a composite solid-state electrolyte, a semi-solid-state electrolyte, and a semi-solid-state battery. This composite solid-state electrolyte can repair the interface between the positive and negative electrode materials during battery cycling, improving cycle stability and extending cycle life.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] The first aspect of the present invention provides a composite solid electrolyte comprising a solid electrolyte and an acesulfame potassium compound; wherein the acesulfame potassium compound has a mass content of not less than 0.5% in the composite solid electrolyte.

[0007] In some specific embodiments, the acesulfame potassium compound has a mass content of 0.5%-5% in the composite solid electrolyte.

[0008] In some specific embodiments, the solid electrolyte in the composite solid electrolyte has a mass content of 95%-99.5%.

[0009] In some specific embodiments, the acesulfame potassium compounds include at least one of acesulfame potassium and its salts, and acesulfame potassium derivatives and their salts.

[0010] In some specific embodiments, the acesulfame potassium salt includes an alkali metal salt.

[0011] In some specific embodiments, the acesulfame potassium derivative and its salt have the structure shown in formula (1).

[0012] Equation (1),

[0013] In equation (1), R1 represents alkali metal ions, H, -CO-C n H 2n+1 -C m1 H 2m1 -CO-C m2 H 2m2+1 R2 is a C1-C3 alkyl or haloalkyl group, n, m1, and m2 are each independent integers from 1 to 3, R2 is H, halogen, C1-C3 alkyl or haloalkyl group, and R3 is a C1-C3 alkyl or haloalkyl group.

[0014] In some specific embodiments, the salt of acesulfame includes at least one of lithium acesulfame, sodium acesulfame, and potassium acesulfame.

[0015] In some specific embodiments, in formula (1), the alkali metal ion includes at least one of potassium ion, sodium ion and lithium ion.

[0016] In some specific embodiments, the halogen in formula (1) includes at least one of fluorine, chlorine, bromine and iodine.

[0017] In some specific embodiments, the solid electrolyte includes an oxide solid electrolyte and / or a sulfide solid electrolyte; the oxide solid electrolyte includes at least one of lithium aluminum titanium phosphate, lithium titanium phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum zirconium tantalum oxide; and the sulfide solid electrolyte includes at least one of lithium tetrathiophosphate, thiogermanium phosphate sulfide, and thiogermanium sulfide.

[0018] In some specific embodiments, the composite solid electrolyte further includes a binder, the binder having a mass content of 0.01%-2% in the composite solid electrolyte, and the binder comprising at least one of polyethylene oxide, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polyacrylic acid, and nitrile rubber.

[0019] A second aspect of the present invention provides a semi-solid electrolyte, comprising an electrolyte and the composite solid electrolyte described in the first aspect of the present invention.

[0020] In some specific embodiments, the mass ratio of the electrolyte to the composite solid electrolyte is (5-30):(70-95).

[0021] In some specific embodiments, the electrolyte is a non-aqueous electrolyte.

[0022] In some specific embodiments, the electrolyte includes lithium salt and organic solvent.

[0023] In some specific embodiments, the lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluorosulfonyl)imide, lithium bis(oxalateborate), lithium difluorooxalateborate, lithium difluorooxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0024] In some specific embodiments, the organic solvent includes at least one of cyclic carbonates, chain carbonates, fluorocarbonates, carboxylic acid esters, and ionic liquids.

[0025] In some specific embodiments, the electrolyte further includes additives, the additives being present in a mass content of 0.1%-10% in the electrolyte, the additives including at least one of vinylene carbonate, vinyl ethylene carbonate, 1,3-propanesulfonate lactone, tris(trimethylsilane)borate, tris(trimethylsilane)phosphate, vinyl sulfite, propylene sulfite, vinyl sulfate, vinyl disulfite, and methane disulfonate.

[0026] In some specific embodiments, the concentration of the lithium salt in the electrolyte is 0.5 mol / L to 2 mol / L.

[0027] In some specific embodiments, the organic solvent has a mass content of 80%-92% in the electrolyte.

[0028] In some specific embodiments, the cyclic carbonate includes at least one of ethylene carbonate, propylene carbonate, and butene carbonate.

[0029] In some specific embodiments, the chain carbonate includes at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, and ethyl propyl carbonate.

[0030] In some specific embodiments, the carboxylic acid ester includes at least one selected from methyl formate, ethyl formate, methyl acetate, and ethyl acetate.

[0031] In some specific embodiments, the fluorocarbonate includes at least one of fluoroethylene carbonate, dimethyl fluorocarbonate, and ethyl fluorocarbonate.

[0032] In some specific embodiments, the ionic liquid includes at least one of 1-ethyl-3-methylimidazolium bisfluorosulfonylimide, 1-butyl-3-methylimidazolium tetrafluoroboric acid, N-methyl-N-propylpyrrolidine bis(trifluoromethanesulfonylimide), triethylmethylammonium bis(fluorosulfonylimide), and trihexyltetradecylphosphine bis(trifluoromethanesulfonylimide).

[0033] A third aspect of the present invention provides a semi-solid battery, comprising a positive electrode, a negative electrode, a separator, and a semi-solid electrolyte as described in the second aspect above.

[0034] Through the above technical solution, the composite solid electrolyte of this invention can improve the long-cycle stability, high-power performance, and interface durability of batteries, especially semi-solid batteries. The reason for this is that acesulfame potassium compounds can form a self-healing, high-strength interface layer during battery charging and discharging. This interface layer can effectively inhibit the continuous consumption of active lithium and the destruction of electrode structures, maintaining its integrity and stability during long-term cycling. It significantly delays the increase in interface impedance caused by lithium dendrite growth and the accumulation of by-reaction products. Furthermore, acesulfame potassium compounds can construct ion transport channels during charging and discharging. Detailed Implementation

[0035] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0036] In a first aspect, some embodiments of the present invention provide a composite solid electrolyte, comprising a solid electrolyte and an acesulfame potassium compound; wherein the mass content of the acesulfame potassium compound in the composite solid electrolyte is not less than 0.5%.

[0037] The composite solid electrolyte in this invention can better improve the cycle life and storage performance of batteries, especially semi-solid batteries.

[0038] The composite solid electrolyte of this invention can be used in lithium-ion batteries, especially in semi-solid lithium-ion batteries. The composite solid electrolyte is placed between the positive and negative electrodes of the lithium-ion battery and, together with a certain amount of electrolyte, can better balance the safety and energy density of the battery.

[0039] While existing semi-solid-state batteries have achieved high energy density, the positive electrode material and silicon-containing material undergo repeated expansion and contraction during cycling, eventually leading to rupture. This causes continuous side reactions between the positive and negative electrodes and the electrolyte, consuming active lithium, increasing interfacial impedance, and the electrolyte repeatedly generating and damaging the solid electrolyte interface during charge-discharge cycles. This results in rapid capacity degradation of the battery and severely affects its lifespan. The composite solid electrolyte in this invention can overcome these problems.

[0040] In this invention, the sulfur and nitrogen elements in the acesulfame potassium compounds in the composite solid electrolyte preferentially undergo electrochemical reduction before the electrode surface during battery charging and discharging, forming an inorganic stable interface layer rich in Li₂S and Li₃N. This artificial SEI film exhibits higher ionic conductivity and excellent mechanical strength, significantly reducing interfacial impedance, effectively suppressing lithium dendrite growth, and improving battery cycle life and storage performance. Simultaneously, the acesulfame potassium compounds act as controllable pore-forming agents in the solid electrolyte matrix. Through their selective dissolution and migration in the electrolyte, they form an ordered microporous structure at the electrode-electrolyte interface, further promoting the construction of ion transport channels. Furthermore, the low solubility of acesulfame potassium compounds in the electrolyte allows them to persist throughout the cell's lifespan, possessing in-situ film formation and dynamic interface repair functions. During battery cycling, the lithium, sulfur, and nitrogen active groups continuously provide film-forming components, achieving "self-healing" of the SEI film. When the interface layer is damaged due to electrode volume expansion or other reasons, the acesulfame potassium compounds can continue to form a new protective layer on the fresh electrode surface. In addition, the microporous structure formed by acesulfame potassium compounds in the electrolyte has an elastic buffering effect, adapting to changes in interfacial stress during cycling, thereby significantly extending the battery cycle life.

[0041] Furthermore, acesulfame potassium compounds are uniformly dispersed in the solid electrolyte and are gradually released during electrolyte wetting and battery cycling. This not only improves the wettability of the electrolyte to the solid electrolyte and optimizes the solid-liquid interface contact, but also constructs a three-dimensional through-hole ion transport network inside the solid electrolyte through its pore-forming effect. This pore structure can effectively reduce ion migration resistance and improve the overall ionic conductivity of the electrolyte.

[0042] According to the present invention, acesulfame potassium compounds mainly function as additives in composite solid electrolytes, and their dosage should not be excessive. In some embodiments, the mass content of the acesulfame potassium compounds in the composite solid electrolyte is 0.5%-5%, for example, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination of two of the above values. Controlling the content of acesulfame potassium compounds within the aforementioned suitable range has a better effect on improving the cycle performance of the battery.

[0043] According to some embodiments of the present invention, the solid electrolyte in the composite solid electrolyte has a mass content of 95%-99.5%, for example, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, or a range of any two of the above values. Controlling the content of the solid electrolyte within the aforementioned suitable range can better improve the cycle performance of the battery while ensuring the performance of the solid electrolyte itself.

[0044] According to some embodiments of the present invention, the acesulfame potassium compounds include at least one of acesulfame acid and its salts, and acesulfame acid derivatives and their salts. That is, the acesulfame potassium compounds include at least one of the group consisting of acesulfame acid, acesulfame acid salts (i.e., acesulfame acid salts), acesulfame acid derivatives, and acesulfame acid derivative salts (i.e., acesulfame acid derivative salts).

[0045] As an example, acesulfame potassium compounds include salts of acesulfame potassium, wherein the salt of acesulfame potassium refers to a salt formed by the combination of acesulfame potassium and a basic ion. In some embodiments, the salt of acesulfame potassium includes an alkali metal salt, that is, a salt formed by acesulfame potassium and an alkali metal. Examples of alkali metals include lithium, sodium, potassium, etc. That is, in some embodiments, the salt of acesulfame potassium includes at least one of lithium acesulfame, sodium acesulfame, and potassium acesulfame, preferably lithium acesulfame and / or potassium acesulfame. The inclusion of the aforementioned acesulfame potassium compounds can better improve the cycle life and storage performance of semi-solid-state batteries because, during the charge and discharge process of the battery, the aforementioned acesulfame potassium compounds more effectively reduce interfacial impedance and inhibit lithium dendrite growth.

[0046] As an example, acesulfame potassium compounds include acesulfame potassium derivatives. In some embodiments, the acesulfame potassium derivatives and their salts have the structure shown in formula (1).

[0047] Equation (1),

[0048] In equation (1), R1 represents alkali metal ions, H, -CO-C n H 2n+1 -C m1 H 2m1 -CO-C m2 H 2m2+1The compounds are C1-C3 alkyl or haloalkyl groups, where n, m1, and m2 are each independent integers from 1 to 3, R2 is H, a halogen, or a C1-C3 alkyl or haloalkyl hydrocarbon, and R3 is a C1-C3 alkyl or haloalkyl group. When R1 is an alkali metal ion (including but not limited to at least one of potassium, sodium, and lithium ions), it refers to acesulfame potassium derivatives including alkali metal salts. The inclusion of the aforementioned acesulfame potassium compounds can better improve the electrochemical performance of semi-solid-state batteries. This is because, during the charge and discharge process of the battery, the aforementioned acesulfame potassium compounds can better control its slow-release pore-forming process and film-forming kinetics, improve the interface between the electrolyte and the solid electrolyte, and reduce ion transport impedance.

[0049] In the above formula (1) of the present invention, "C1-C3 alkyl" refers to a saturated chain hydrocarbon group composed of carbon atoms and hydrogen atoms with a carbon atom number between 1 and 3. The aforementioned alkyl can be a straight-chain alkyl or a branched-chain alkyl. The present invention does not have any special restrictions on this. The C1-C3 alkyl that can be listed in the present invention are C1 alkyl (e.g., methyl), C2 alkyl (e.g., ethyl), and C3 alkyl (e.g., isopropyl, n-propyl, etc.).

[0050] In the above formula (1) of the present invention, "C1-C3 haloalkyl" refers to a group in which at least one H in the above C1-C3 alkyl group is replaced by a halogen, and there are no special limitations on the substitution position and substitution.

[0051] According to the present invention, in some embodiments, the halogen of formula (1) includes at least one of fluorine, chlorine, bromine and iodine, preferably chlorine. The inclusion of the aforementioned acesulfame potassium compounds and their salts can better improve the cycle life and storage performance of semi-solid-state batteries. This is because, during the charging and discharging process of the battery, the aforementioned acesulfame potassium compounds can better improve the interface performance of the battery or better construct fast ion channels in the interface layer.

[0052] According to some embodiments of the present invention, in formula (1), R1 is H, -CO-C n H 2n+1 -C m1 H 2m1 -CO-C 2m2 H m2+1 .

[0053] According to the present invention, in some embodiments, in formula (1), R2 is H, C1-C3 alkyl.

[0054] According to the present invention, in some embodiments, R3 of formula (1) is a C1-C3 alkyl group.

[0055] As an example, in formula (1), R1 is H, R2 is methyl, and R3 is methyl. That is, the structure of the acesulfame potassium derivative is shown in formula (1-1), and its CAS number is 25716-43-2.

[0056] Equation (1-1).

[0057] As an example, in formula (1), R1 is -CH2-CO-CH3, R2 is H, and R3 is methyl. That is, the structure of the acesulfame potassium derivative is shown in formula (1-2), and its CAS number is 1621619-23-5.

[0058] Equation (1-2).

[0059] As an example, in formula (1), R1 is H, R2 is H, halogen, C1-C3 alkyl or haloalkyl, and R3 is C1-C3 alkyl or haloalkyl.

[0060] As an example, acesulfame potassium compounds include combinations of acesulfame potassium salts and acesulfame potassium derivatives. The combination of acesulfame potassium salts and acesulfame potassium derivatives used in this invention can better improve the cycle stability, high-power performance, and interface durability of the battery. As long as the objectives of this invention are achieved, the ratio of the two components is not particularly limited; for example, the mass ratio of acesulfame potassium salt to acesulfame potassium derivative is (2-5):1, such as 2:1, 3:1, 4:1, or 5:1.

[0061] This invention does not specifically limit the type of solid electrolyte; it can be any solid electrolyte in the art. In some embodiments, the solid electrolyte includes oxide solid electrolytes and / or sulfide solid electrolytes. That is, the acesulfame potassium compounds used in this invention can be combined with existing oxide solid electrolytes and / or sulfide solid electrolytes to suppress side reactions and protect the solid electrolyte structure.

[0062] According to some embodiments of the present invention, the oxide solid electrolyte includes lithium titanium aluminum phosphate (LiTi). x Al1 1- x PO4, 0 < x < 1), lithium titanium phosphate (LiTiPO4), lithium lanthanum zirconium oxide (Li7La3Zr2O) 12 (LLZO) and lithium lanthanum zirconium tantalum oxide (Li 6.4 La3Zr 1.4 Ta 0.6 O 12At least one of the following (abbreviated as LLZTO). In this invention, the synergistic effect of acesulfame potassium compounds with the aforementioned oxide solid electrolytes can significantly reduce the interfacial impedance of the battery and improve the cycle stability of the battery while maintaining the bulk stability and safety advantages of oxide solid electrolytes.

[0063] According to the present invention, in some embodiments, the sulfide solid electrolyte includes lithium tetrathiophosphate (Li3PS4), sulfur-germanium phosphorus sulfide (e.g., LGPS type electrolyte, specifically Li...). 10 GeP2S 12 The present invention utilizes at least one of acesulfame potassium compounds and sulfide-type sulfides (such as Li6PS5Br and Li6PS5Cl). In this invention, the synergistic effect of acesulfame potassium compounds with the aforementioned oxide solid electrolytes can fully leverage the high-speed ion transport advantages of sulfide solid electrolytes while further enhancing the cycle stability and safety of the battery.

[0064] According to the present invention, when the composite solid electrolyte is used in battery assembly, it can be made into a self-supporting sheet and attached to one or both sides of a separator, or it can be coated onto one or both sides of the separator and dried to form a composite solid electrolyte film layer. To increase the formation of a dense and complete structure during the molding process, in some embodiments, the composite solid electrolyte also includes a binder. The content of the binder in the composite solid electrolyte can be selected within a wide range. As an example, the mass content of the binder in the composite solid electrolyte is 0.01%-2%. There are no particular limitations on the type of binder, including but not limited to at least one of: polyethylene oxide, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polyacrylic acid, and nitrile rubber.

[0065] There is no particular limitation on the thickness of the self-supporting sheet, which can be selected as needed. For example, the thickness of the self-supporting sheet is 100 micrometers to 500 micrometers. There is no particular limitation on the thickness of the composite solid electrolyte membrane layer after drying, which can be selected as needed. For example, the thickness of the composite solid electrolyte membrane layer is 30 micrometers to 150 micrometers.

[0066] The present invention does not impose any particular limitations on the preparation method of the composite solid electrolyte, as long as the various components of the composite solid electrolyte can be mixed uniformly and shaped as required. In some embodiments, the solid electrolyte, acesulfame potassium compound, and optionally a binder are mixed by at least one of ball milling, grinding, and resonance. The aforementioned ball milling, grinding, and resonance are each independently dry mixing or wet mixing, wherein dry mixing refers to mixing the various components in the absence of solvent, and wet mixing refers to mixing the various components in a solvent (e.g., N-methylpyrrolidone NMP).

[0067] As an example, sulfide solid electrolytes and acesulfame potassium compounds are mixed evenly by ball milling and then pressed into tablets.

[0068] As an example, an oxide solid electrolyte, acesulfame potassium compound, and optionally a binder and solvent are mixed uniformly by wet milling to obtain a slurry. The slurry is then coated onto a corresponding substrate and dried to form a corresponding composite solid electrolyte layer. The solid content of the slurry can be selected within a wide range, for example, 30wt%-60wt%.

[0069] According to the present invention, the composite solid electrolyte is particularly suitable for semi-solid batteries and can overcome the defects of semi-solid batteries such as cycle performance. The electrolyte of a semi-solid battery is a solid-liquid hybrid system, which adds a solid electrolyte to a traditional liquid electrolyte. In a second aspect, some embodiments of the present invention provide a semi-solid electrolyte, including an electrolyte and the composite solid electrolyte provided in any of the above embodiments of the present invention.

[0070] The semi-solid electrolyte in this invention can overcome the shortcomings of semi-solid batteries, such as poor cycle life, rate performance, and storage stability, while ensuring the safety performance of the semi-solid battery. The reason is that the electrolyte can fully wet the composite solid electrolyte, providing an initial high-efficiency ion transport channel and initiating the electrochemical reaction. The acesulfame potassium compounds in the composite solid electrolyte have low solubility in the electrolyte. As the semi-solid cell is cycled, the acesulfame potassium compounds repair the positive and negative electrode interfaces during charging and are then decomposed and consumed. The acesulfame potassium compounds remaining in the electrolyte continue to dissolve in the electrolyte, achieving the effect of slow-release additives. This better balances the excellent interfacial contact of the electrolyte with the structural stability of the composite solid electrolyte, thereby significantly reducing the solid-solid interface impedance and effectively inhibiting lithium dendrite growth. At the same time, the "self-healing" function of the acesulfame potassium compounds can maintain the integrity of the interface for a long time.

[0071] According to the present invention, the respective contents of the electrolyte and the composite solid electrolyte in the semi-solid electrolyte are not particularly limited as long as the purpose of the present invention can be achieved. In some embodiments, the mass ratio of the electrolyte to the composite solid electrolyte is (5-30):(70-95), for example, 5:95, 8:92, 10:90, 15:85, 20:80, 25:75, 30:70. Controlling the ratio of the electrolyte to the composite solid electrolyte within the aforementioned suitable range can simultaneously achieve better results in terms of battery ionic conductivity, cycle stability, and safety.

[0072] According to some embodiments of the present invention, the electrolyte is a non-aqueous electrolyte, which refers to an ion-conducting liquid that does not contain water.

[0073] The present invention does not have a specific limitation on the composition of the electrolyte, as long as it can achieve the purpose of the present invention. In some embodiments, the electrolyte includes lithium salt and organic solvent.

[0074] The lithium salt described above can be any known lithium salt in the art. In some embodiments, the lithium salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluorosulfonyl)imide (LiTFSI), lithium bis(oxalateborate)borate (LiBOB), lithium difluorooxalateborate (LiDFOP), lithium difluorooxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0075] According to the present invention, the content of lithium salt in the electrolyte can be selected within a wide range as long as the purpose of the present invention can be achieved. In some embodiments, the concentration of lithium salt in the electrolyte is 0.5 mol / L-2 mol / L, for example, 0.5 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 2 mol / L, and the specific concentration is not limited.

[0076] The organic solvent described above can be any known organic solvent in the art. In some embodiments, the organic solvent includes at least one of cyclic carbonates, chain carbonates, fluorocarbonates, carboxylic acid esters, and ionic liquids.

[0077] As an example, the cyclic carbonates include, but are not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), and butene carbonate (BC).

[0078] As an example, the chain carbonates include, but are not limited to, at least one of: dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), methyl propyl carbonate (MPC), and ethyl propyl carbonate (EPC).

[0079] As an example, the fluorocarbonate includes at least one of fluoroethylene carbonate (FEC), dimethyl fluorocarbonate (FMMC), and methyl ethyl fluorocarbonate (FEMC).

[0080] As an example, the carboxylic acid esters include, but are not limited to, at least one of methyl formate (MeF), ethyl formate (EtF), methyl acetate (MA), ethyl acetate (EA), methyl propionate (MP), ethyl propionate (EP), and propyl propionate (PP).

[0081] As an example, the ionic liquid includes, but is not limited to, at least one of: 1-ethyl-3-methylimidazolium bisfluorosulfonylimide, 1-butyl-3-methylimidazolium tetrafluoroboric acid, N-methyl-N-propylpyrrolidine bis(trifluoromethanesulfonylimide), triethylmethylammonium bis(fluorosulfonylimide), and trihexyltetradecylphosphine bis(trifluoromethanesulfonylimide).

[0082] According to the present invention, the content of organic solvent in the electrolyte can be selected within a wide range. In some embodiments, the mass content of the organic solvent in the electrolyte is 80%-92%, for example, 80%, 82%, 85%, 88%, 90%, 92%, and there is no specific limitation.

[0083] The aforementioned organic solvents can be used in combination of different types of organic solvents. In some embodiments, the cyclic carbonate in the organic solvent has a volume content of 10%-35%; in some embodiments, the chain carbonate in the organic solvent has a volume content of 10%-85%; in some embodiments, the carboxylic acid ester in the organic solvent has a volume content of 0%-40%; in some embodiments, the fluorinated carbonate in the organic solvent has a volume content of 0%-20%; and in some embodiments, the ionic liquid in the organic solvent has a volume content of 0%-10%.

[0084] As an example, the organic solvents are ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC) in a volume ratio of 30:50:10:10.

[0085] According to the present invention, in some embodiments, the electrolyte further includes additives, said additives including at least one selected from vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propanesulfonate lactone (PS), tris(trimethylsilane)borate (TMSB), tris(trimethylsilane)phosphate (TMSP), vinyl sulfite (ES), propylene sulfite (PS), vinyl sulfate (DTD), vinyl disulfide (DSD), and methane disulfonate (MMDS). The amount of additives can be selected within a wide range. As an example, the additives in the electrolyte are present in a mass content of 0.1%-10% (e.g., 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%). The present invention, by further introducing other additives into the electrolyte, is more conducive to improving the cell cycle life, rate performance, and storage performance.

[0086] The composite solid electrolyte of the present invention can be used in semi-solid batteries. In a third aspect, some embodiments of the present invention provide a semi-solid battery, including a positive electrode, a negative electrode, a separator, and the semi-solid electrolyte as provided in any of the above embodiments.

[0087] The materials and preparation methods of the semi-solid battery described in this invention, excluding the semi-solid electrolyte, can be carried out in accordance with the practices in this field, and can all achieve effects such as significantly improving battery cycle life and reducing interface impedance.

[0088] According to the present invention, the above-mentioned semi-solid battery is preferably a lithium-ion semi-solid battery.

[0089] According to some embodiments of the present invention, the battery further includes a positive electrode sheet containing a positive electrode active material, a negative electrode sheet containing a negative electrode active material, and a separator.

[0090] The positive electrode sheet can be a conventional positive electrode sheet in the art. For example, the positive electrode sheet includes a positive current collector and a positive active material layer coated on one or both surfaces of the positive current collector. The positive active material layer includes a positive active material, a conductive agent, and a binder. In some embodiments, the positive active material includes the substance shown in formula (A) or the substance shown in formula (B).

[0091] LiNi x M 2-x A y O r B p Formula (A),

[0092] In formula (A), 0≤x≤1, 0≤y≤0.05, 1≤r≤4, 0≤p≤4, r+P≤4, M includes Mn and / or Al, A includes at least one of Zr, Zn, Cu, Cr, Fe, V, Ti, Sr, Sb, Sn, Y, W, Al and Nb, and B includes at least one of F, Cl and Br;

[0093] nLi2MnO3·(1-n)LiMO2 formula (B).

[0094] In formula (B), M includes at least one of Ni, CO, and Al, and 0 ≤ n ≤ 1.

[0095] According to some embodiments of the present invention, the mass content of the positive electrode active material is 80%-99.8% based on the total weight of the positive electrode active material layer, the mass content of the conductive agent is 0.1%-10%, and the mass content of the binder is 0.1%-10%.

[0096] The negative electrode sheet can be a conventional negative electrode sheet in the art. For example, the negative electrode sheet includes a negative current collector and a negative active material layer coated on one or both surfaces of the negative current collector. The negative active material layer includes a negative active material, a conductive agent, and a binder.

[0097] According to some embodiments of the present invention, the negative electrode active material includes at least one of graphite (artificial graphite, natural graphite), silicon materials (spherical silicon materials, hollow spherical silicon materials, nanorod silicon materials, nanowire silicon materials, etc.), silicon-carbon materials (spherical silicon-carbon materials, hollow spherical silicon-carbon materials, nanorod silicon-carbon materials, nanowire silicon-carbon materials, etc.), silicon-oxygen materials (spherical silicon-oxygen materials, hollow spherical silicon-oxygen materials, nanorod silicon-oxygen materials, nanowire silicon-oxygen materials, etc.) and lithium titanate.

[0098] According to some embodiments of the present invention, based on the total weight of the negative electrode active material layer, the mass content of the negative electrode active material is 80%-99.8%, the mass content of the conductive agent is 0.1%-10%, and the mass content of the binder is 0.1%-10%.

[0099] The conductive agents and binders mentioned above are all conventional substances in the field, and will not be described in detail in this invention.

[0100] According to the present invention, the diaphragm includes diaphragms conventionally used in the art, such as at least one selected from polyethylene, polypropylene, polyvinylidene fluoride, polyimide, polyethersulfone, polycarbonate, polyphenylene sulfide, polyethylene oxide, and polymethyl methacrylate.

[0101] As an example, the present invention can mix solid electrolyte, acesulfame potassium compound and optionally binder uniformly by dry ball milling, press them into sheets and place them on at least one side of the separator to obtain a composite solid electrolyte membrane, which is then assembled according to conventional semi-solid battery assembly methods.

[0102] As an example, the present invention can mix a solid electrolyte, an acesulfame potassium compound, and an optional binder into a slurry by wet ball milling, and coat the slurry onto at least one side of a diaphragm to form a membrane layer, thereby obtaining a composite solid electrolyte membrane.

[0103] The present invention will be described in detail below through embodiments.

[0104] Example 1

[0105] Positive electrode sheet: The positive electrode current collector is 12μm aluminum foil, the positive electrode active material is NCM811 (DangSheng Technology), the binder is PVDF 5130, the conductive agent is SP, and the mass ratio of positive electrode active material, binder and conductive agent is 98:1:1;

[0106] Negative electrode sheet: The negative electrode current collector is an 8μm copper foil, the negative electrode active material is artificial graphite (Shangtai) and silicon carbide (Putailai) in a mass ratio of 80:20, the conductive agent is SP, the binder is CMC and SBR, and the mass ratio of negative electrode active material, conductive agent and binder is 96:1.5:2.5.

[0107] Non-aqueous electrolyte: EC, EMC, DEC, and FEC in a volume ratio of 30:50:10:10 are used as organic solvents, containing 1.2 mol / L LiPF6, 1.5 wt% DTD, 0.5 wt% TMSP, and 1 wt% LiPO2F2.

[0108] Composite solid electrolyte membrane: a sulfide solid electrolyte (Li) with a mass ratio of 95:5. 10 GeP2S 12 The composite solid electrolyte was obtained by uniformly mixing lithium acesulfame potassium and lithium acesulfame potassium using ball milling. The mixture was then pressed into sheets (200 micrometers thick) and placed on both sides of a diaphragm (commercial PP diaphragm) to obtain a composite solid electrolyte membrane.

[0109] Semi-solid battery: A semi-solid battery is obtained by assembling the above-mentioned positive electrode, negative electrode, composite solid electrolyte membrane and non-aqueous electrolyte in a mold battery; wherein the mass ratio of non-aqueous electrolyte to composite solid electrolyte is 20:80.

[0110] Example 2

[0111] The method is the same as in Example 1, except that the mass ratio of the sulfide solid electrolyte to lithium acesulfame potassium is 99.5:0.5.

[0112] The rest is the same as in Example 1, and the composite solid electrolyte membrane and the corresponding semi-solid battery are finally prepared.

[0113] Example 3

[0114] The method is the same as in Example 1, except that the composite solid electrolyte membrane is prepared by mixing lithium lanthanum zirconium oxide solid electrolyte, lithium acesulfame potassium and PTFE binder in NMP by wet milling in a mass ratio of 97.5:2:0.5 to form a slurry (the solid content of the slurry is 50wt%). The slurry is coated on both sides of the membrane and then dried in a vacuum oven at 80°C for 12 hours to form a membrane layer with a thickness of 60μm, thus obtaining the composite solid electrolyte membrane.

[0115] The rest is the same as in Example 1, and a semi-solid battery is finally prepared.

[0116] Example 4

[0117] The method is the same as in Example 3, except that lithium acesulfame potassium is replaced with lithium acesulfame potassium.

[0118] The rest is the same as in Example 3, and a semi-solid battery is finally prepared.

[0119] Example 5

[0120] The method is the same as in Example 3, except that the mass ratio of lithium lanthanum zirconium oxide solid electrolyte, lithium acesulfame potassium, and PTFE binder is 89.5:10:0.5.

[0121] The rest is the same as in Example 3, and a semi-solid battery is finally prepared.

[0122] Example 6

[0123] The method of Example 3 is followed, except that lithium acesulfame potassium is replaced with acesulfame potassium derivative A (CAS: 25716-43-2).

[0124] The rest is the same as in Example 3, and a semi-solid battery is finally prepared.

[0125] Example 7

[0126] The method of Example 3 is followed, except that lithium acesulfame potassium is replaced with chloroacesulfame potassium (CAS: 72827-08-8).

[0127] The rest is the same as in Example 3, and a semi-solid battery is finally prepared.

[0128] Example 8

[0129] The method of Example 3 is followed, except that lithium acesulfame potassium is replaced with lithium acesulfame potassium and acesulfame potassium derivative A (CAS:25716-43-2) in a mass ratio of 1.6:0.4.

[0130] The rest is the same as in Example 3, and a semi-solid battery is finally prepared.

[0131] Example 9

[0132] The method of Example 3 is followed, except that lithium acesulfame potassium is replaced with lithium acesulfame potassium and acesulfame potassium derivative A (CAS:25716-43-2) in a mass ratio of 1.4:0.6.

[0133] The rest is the same as in Example 3, and a semi-solid battery is finally prepared.

[0134] Example 10

[0135] The method of Example 3 is followed, except that lithium acesulfame potassium is replaced with potassium acesulfame potassium and chloroacesulfame potassium in a mass ratio of 1.6:0.4.

[0136] The rest is the same as in Example 3, and a semi-solid battery is finally prepared.

[0137] Example 11

[0138] The method is the same as in Example 3, except that lithium acesulfame potassium is replaced with potassium acesulfame potassium and chloroacesulfame potassium in a mass ratio of 1.4:0.6.

[0139] The rest is the same as in Example 3, and a semi-solid battery is finally prepared.

[0140] Example 12

[0141] The method of Example 3 is followed, except that lithium acesulfame potassium is replaced with lithium acesulfame potassium and acylsulfamic acid derivative B (CAS:1621619-23-5) in a mass ratio of 1.5:0.5.

[0142] The rest is the same as in Example 3, and a semi-solid battery is finally prepared.

[0143] Comparative Example 1

[0144] The method of Example 3 is the same, except that in the composite solid electrolyte membrane, lithium lanthanum zirconium oxide solid electrolyte and PTFE binder are mixed in NMP by wet grinding at a mass ratio of 99.5:0.5 to form a slurry.

[0145] The rest is the same as in Example 3, and the composite solid electrolyte membrane and the corresponding semi-solid battery are finally prepared.

[0146] Comparative Example 2

[0147] The method is the same as in Example 1, except that the composite solid electrolyte membrane is prepared by wet milling in NMP with lithium lanthanum zirconium oxide solid electrolyte, lithium acesulfame potassium and PTFE binder in a mass ratio of 99.3:0.2:0.5 to form a slurry.

[0148] The rest is the same as in Example 3, and the composite solid electrolyte membrane and the corresponding semi-solid battery are finally prepared.

[0149] Performance testing

[0150] The semi-solid-state batteries in Examples 1-12 and Comparative Examples 1-2 were tested as follows:

[0151] Cycle capacity retention: The remaining capacity after 500 charge-discharge cycles at 1C / 1C current is divided by the initial capacity and multiplied by 100% as the cycle capacity retention.

[0152] Rate performance: The 5C rate capacity retention rate of the semi-solid-state battery is obtained by dividing the 5C discharge capacity by the 0.5C discharge capacity.

[0153] DCR growth rate: The capacity corresponding to 50% SOC is calibrated in the initial stage. The battery's DCR is obtained by dividing the voltage difference after 10 seconds of 5C discharge by the current. The DCR growth rate is calculated by comparing the DCR at the end of the test with the DCR in the initial state.

[0154] The test results are shown in Table 1.

[0155] Table 1 Performance Test Results

[0156]

[0157] The test results above show that the composite solid electrolyte in this invention can improve the cycle stability, high power performance and interface durability of semi-solid batteries.

[0158] Furthermore, substances such as acesulfame acid, acesulfame acid derivatives, alkali metal salts of acesulfame acid, and halogenated acesulfame acid have a significant effect on improving the electrochemical performance of semi-solid-state batteries. Among them, lithium acesulfame oxide performs better than other alkali metal salts in lithium-ion semi-solid-state batteries. Halogenated acesulfame acid has stronger polarity, which is beneficial to the transport of lithium ions at the electrode and electrolyte interface, resulting in better overall performance. In this invention, acesulfame acid derivatives can also be used in combination with acesulfame acid salts for even better performance.

[0159] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, 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 composite solid electrolyte, characterized in that, Including solid electrolytes and acesulfame potassium compounds; The composite solid electrolyte is obtained by uniformly mixing a solid electrolyte and an acesulfame potassium compound, and then molding it as needed. The acesulfame potassium compound has a mass content of 0.5%-5% in the composite solid electrolyte; The acesulfame potassium compounds have the structure shown in formula (1). Equation (1), In equation (1), R1 represents alkali metal ions, H, -CO-C n H 2n+1 -C m1 H 2m1 -CO-C m2 H 2m2+1 R2 is a C1-C3 alkyl or haloalkyl group, where n, m1, and m2 are each independent integers from 1 to 3, R2 is H, halogen, C1-C3 alkyl or haloalkyl group, and R3 is a C1-C3 alkyl or haloalkyl group. The solid electrolyte includes oxide solid electrolytes and / or sulfide solid electrolytes; the oxide solid electrolyte includes at least one of lithium titanium aluminum phosphate, lithium titanium phosphate, lithium lanthanum zirconium oxide, and lithium lanthanum zirconium tantalum oxide; the sulfide solid electrolyte includes at least one of lithium tetrathiophosphate, thiogermanium phosphate sulfide, and thiogermanium sulfide.

2. The composite solid electrolyte according to claim 1, characterized in that, The solid electrolyte in the composite solid electrolyte has a mass content of 95%-99.5%.

3. The composite solid electrolyte according to claim 1, characterized in that, In formula (1), the alkali metal ion includes at least one of potassium ion, sodium ion and lithium ion; And / or, in formula (1), the halogen includes at least one of fluorine, chlorine, bromine and iodine.

4. The composite solid electrolyte according to any one of claims 1-3, characterized in that, The composite solid electrolyte also includes a binder, the binder having a mass content of 0.01%-2% in the composite solid electrolyte, and the binder comprising at least one of polyethylene oxide, polyvinylidene fluoride, polytetrafluoroethylene, polyacrylonitrile, polyacrylic acid, and nitrile rubber.

5. A semi-solid electrolyte, characterized in that, Includes the electrolyte and the composite solid electrolyte as described in any one of claims 1-4.

6. The semi-solid electrolyte according to claim 5, characterized in that, The mass ratio of the electrolyte to the composite solid electrolyte is (5-30):(70-95). And / or, the electrolyte is a non-aqueous electrolyte; And / or, the electrolyte comprises lithium salt and organic solvent.

7. The semi-solid electrolyte according to claim 6, characterized in that, The lithium salt includes at least one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluorosulfonyl)imide, lithium bis(oxalateborate), lithium difluorooxalateborate, lithium difluorooxalate phosphate, and lithium tetrafluorooxalate phosphate. And / or, the organic solvent includes at least one of cyclic carbonates, chain carbonates, fluorocarbonates, carboxylic acid esters, and ionic liquids; And / or, the electrolyte further includes additives, the additives being present in the electrolyte at a mass content of 0.1%-10%, the additives being at least one selected from vinylene carbonate, vinyl ethylene carbonate, 1,3-propanesulfonate lactone, tris(trimethylsilane)borate, tris(trimethylsilane)phosphate, vinyl sulfite, propylene sulfite, vinyl sulfate, vinyl disulfite, and methane disulfonate; And / or, the concentration of the lithium salt in the electrolyte is 0.5 mol / L-2 mol / L; And / or, the organic solvent in the electrolyte has a mass content of 80%-92%.

8. The semi-solid electrolyte according to claim 7, characterized in that, The cyclic carbonate includes at least one of ethylene carbonate, propylene carbonate, and butene carbonate; And / or, the chain carbonate includes at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate and ethyl propyl carbonate; And / or, the carboxylic acid ester includes at least one of methyl formate, ethyl formate, methyl acetate, and ethyl acetate; And / or, the fluorocarbonate includes at least one of fluoroethylene carbonate, dimethyl fluorocarbonate and ethyl fluorocarbonate; And / or, the ionic liquid comprises at least one of 1-ethyl-3-methylimidazolium bisfluorosulfonylimide, 1-butyl-3-methylimidazolium tetrafluoroboric acid, N-methyl-N-propylpyrrolidine bis(trifluoromethanesulfonylimide), triethylmethylammonium bis(fluorosulfonylimide), and trihexyltetradecylphosphine bis(trifluoromethanesulfonylimide).

9. A semi-solid-state battery, characterized in that, It includes a positive electrode, a negative electrode, a separator, and a semi-solid electrolyte as described in any one of claims 5-8.

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