Lithium supplement agent, gel electrolyte precursor, gel electrolyte and semi-solid lithium ion secondary battery

Abstract

The invention discloses a lithium supplement agent, a gel electrolyte precursor, a gel electrolyte and a semi-solid lithium ion secondary battery, and relates to the technical field of semi-solid lithium ion secondary batteries. The lithium supplement agent comprises a compound as shown in a formula I and / or a formula II, wherein R is CiF (2i + 1) Oj, 1 < = i < = 12, and 0 < = j < = 6; x is CmF2mOn, 1 < = m < = 8, and 0 < = n < = 4. By adopting the novel lithium supplementing agent, the lithium supplementing agent slowly supplements lithium in the charge-discharge cycle process after the gel electrolyte is cured, so that the cycle life of a battery cell is prolonged, the lithium supplementing agent forms a polyfluoroalkane derivative after releasing lithium, the polyfluoroalkane derivative has film-forming and flame-retardant characteristics, and the thermal safety performance of the battery is improved.

Description

Technical Field

[0001] This application relates to the technical field of semi-solid lithium-ion secondary batteries, specifically to lithium replenishment agents, gel electrolyte precursors, gel electrolytes, and semi-solid lithium-ion secondary batteries. Background Technology

[0002] With the rapid development of the new energy industry, the research and development of rechargeable lithium-ion batteries that combine high energy density and high safety has become a core objective for technological breakthroughs. Semi-solid-state batteries, with their superior overall performance, are emerging as an important technological path to achieve this goal. Currently, mainstream high-energy-density semi-solid-state batteries generally employ high-nickel ternary cathode materials, a high proportion of silicon / graphite composite anodes, and gelled electrolyte systems, effectively enhancing the energy density potential of the cell while exhibiting significant advantages in thermal stability and leakage risk control.

[0003] Current high-energy-density systems commonly employ high-nickel cathodes and high-proportion silicon / graphite anodes. However, silicon-based materials undergo significant volume expansion during charge and discharge, easily leading to electrode structure rupture and repeated breakage and regeneration of the solid electrolyte interphase (SEI). Simultaneously, the ionic conductivity of gel electrolytes decreases after solidification, worsening electrode / electrolyte interface kinetics and further exacerbating interfacial instability. These factors result in the continuous consumption of active lithium ions during cycling, causing irreversible capacity decay and increased internal resistance, severely impacting the battery's initial cycle efficiency and long-term cycle performance. To compensate for lithium loss, the industry commonly employs chemical lithium replenishment agents for pre-lithiation or post-lithiation replenishment after electrolyte addition.

[0004] However, existing lithium replenishing agents have many limitations: On the one hand, traditional inorganic lithium salt-based lithium replenishing agents have high reactivity and are difficult to control in the battery cycle process. They usually release a large number of lithium ions in a concentrated manner during the formation stage, causing local lithium deposition or even lithium dendrite growth, which poses a safety hazard. Moreover, the products after lithium release have high oxidizing properties, which can easily cause the decomposition of the electrolyte at the positive electrode interface. On the other hand, although some organic lithium replenishing agents have good solubility, their redox potentials are mismatched and their cycle stability is poor. They are prone to side reactions or premature decomposition in gel electrolytes and cannot continuously replenish lithium in long-term cycles. Summary of the Invention

[0005] To address at least one of the problems mentioned in the background art, this application provides a lithium replenishing agent, a gel electrolyte precursor, a gel electrolyte, and a semi-solid lithium-ion secondary battery. By employing a novel organic lithium salt electrolyte lithium replenishing agent, the lithium replenishing agent slowly replenishes lithium during charge-discharge cycles after the gel electrolyte has solidified, thereby improving the cycle life of the battery cell. Furthermore, after the lithium replenishing agent releases lithium, it can form polyfluorinated alkane derivatives, which have film-forming and flame-retardant properties, thereby improving the thermal safety performance of the battery.

[0006] The specific technical solutions provided in this application are as follows: In a first aspect, a lithium replenishing agent is provided, comprising compounds as shown in Formula I and / or Formula II: ; Where R is C i F (2i+1) O j , 1≤i≤12, 0≤j≤6; X is C m F 2m O n , 1≤m≤8, 0≤n≤4.

[0007] In one specific embodiment, the lithium replenishing agent comprises a compound with the following structural formula:

[0008]

[0009] At least one of them; In one specific embodiment, the lithium supplement is .

[0010] In a first aspect, a gel electrolyte precursor is provided, comprising the lithium supplementing agent as described above; Based on the total mass of the gel electrolyte precursor, the mass fraction of the lithium supplement is... It ranges from 1.0% to 3.5%.

[0011] In one specific embodiment, the gel electrolyte precursor further includes: a copolymer monomer, a crosslinking monomer, a gas-generating additive, and a drag-reducing additive; Based on the total mass of the gel electrolyte precursor, the mass fraction of each component is as follows: mass fraction of copolymer monomers The percentage is 0.3% to 1.5%. mass fraction of cross-linked monomers The percentage is 1.0% to 3.0%; Improve the mass fraction of gas-producing additives The percentage is 0.5% to 3.5%. Mass fraction of drag-reducing additives It ranges from 0.5% to 1.5%.

[0012] In one specific embodiment, based on the total mass of the gel electrolyte precursor, the mass fraction of each component is as follows: Mass fraction of lithium supplement It ranges from 3.0% to 3.5%. mass fraction of copolymer monomers The percentage is 0.9% to 1.5%. mass fraction of cross-linked monomers It ranges from 1.0% to 2.1%; Improve the mass fraction of gas-producing additives It ranges from 1.0% to 1.5%; Mass fraction of drag-reducing additives It ranges from 0.5% to 1.0%.

[0013] Thirdly, a gel electrolyte is provided, which is prepared by gelation of the gel electrolyte precursor as described above.

[0014] Fourthly, a semi-solid lithium-ion secondary battery is provided, comprising a gel electrolyte, which is prepared by gelation of the gel electrolyte precursor described above.

[0015] In one specific embodiment, the semi-solid lithium-ion secondary battery further includes a negative electrode sheet, which includes a negative electrode material, and the negative electrode material includes a silicon-based material.

[0016] In one specific embodiment, the mass fraction of silicon-based material is calculated based on the total mass of the negative electrode material. The percentage is 10.0% to 30.0%; In one specific embodiment, the mass fraction of silicon-based material It ranges from 15% to 25%.

[0017] In one specific embodiment, the mass fraction of silicon-based material It is 15% to 20%.

[0018] In one specific embodiment, the semi-solid-state lithium-ion secondary battery satisfies the following formula: ; in, , It can be any one of the following values: 10.0, 11.6, 13.3, 15.5, or 16.1. It can be any one of 16.8, 17.4, 20.9, or 25.0.

[0019] Beneficial Effects: The lithium replenishing agent provided in this application is added to the gel electrolyte precursor. After the gel electrolyte precursor solidifies, the lithium replenishing agent slowly replenishes lithium during battery charge-discharge cycles. The lithium replenishing agent is oxidized by the lithium-releasing positive electrode active material on the positive electrode side, generating lithium ions, sulfur dioxide, and fluorinated alkyl radicals, and releasing electrons. The reaction product, sulfur dioxide, can act as an additive, undergoing reduction and decomposition on the negative electrode side to participate in film formation. The fluorinated alkyl radicals couple to generate fluorinated alkanes. The positive electrode active material, having gained electrons, continues the battery charging reaction, releasing electrons and lithium ions, and generating active lithium on the negative electrode side.

[0020] The lithium replenishing agent in this application slowly replenishes lithium during battery charge-discharge cycles, effectively mitigating the continuous consumption of active lithium and thus significantly improving the cycle life of the battery cell. Furthermore, the lithium replenishing agent generates fluorinated alkanes after lithium release. These fluorinated alkanes possess both interfacial film-forming ability and flame-retardant properties, contributing to improved battery cycle stability and safety performance. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0023] Current high-energy-density batteries mostly employ high-nickel cathodes and silicon / graphite anodes with high silicon content. However, silicon materials undergo significant volume expansion during cycling, easily leading to electrode structure cracking and repeated breakage and regeneration of the SEI film. Simultaneously, the ionic conductivity of the gel electrolyte in semi-solid-state batteries decreases, and interfacial ion transport kinetics become sluggish, further exacerbating interfacial instability. These factors collectively cause continuous consumption of active lithium, resulting in irreversible capacity loss and increased internal resistance, severely impacting initial efficiency and cycle life.

[0024] Existing lithium supplements have significant drawbacks. For example, inorganic lithium supplements have high reactivity, making it difficult to control the release rate. They tend to release lithium in the first week, inducing lithium deposition or even dendrite growth, which poses safety risks. Some organic lithium supplements have good solubility and reversible reactions, but their redox potentials are mismatched, making them prone to side reactions or premature decomposition in gel systems, which makes it difficult to achieve long-term and stable lithium supplementation.

[0025] To address the above problems, this application provides the following embodiments: In one embodiment, this application provides a lithium replenishing agent comprising compounds as shown in Formula I and / or Formula II: ; Where R is C i F (2i+1) O j , 1≤i≤12, 0≤j≤6; X is Cm F 2m O n , 1≤m≤8, 0≤n≤4.

[0026] In one specific embodiment, the lithium replenishing agent comprises a compound with the following structural formula:

[0027]

[0028] At least one of them; In one specific embodiment, the lithium supplement is .

[0029] The lithium supplements used in this application were synthesized using commercially available alternatives or by referring to literature through polyfluoroiodides. The lithium supplements used in this application (except for commercially available lithium trifluoromethyl sulfinate) were synthesized with reference to relevant literature (Shichao Tian, ​​Ning Chen, KeguangCheng, Quande Wang, Radical Acylfluoroalkylation of 1,3-Enynes via N-Heterocyclic Carbene / Photoredox Cooperative Catalysis [J]. Org. Lett. 2024,26(20), 4351−4355. DOI: 10.1021 / acs.orglett.4c01372). All other reagents, methods, and equipment used were conventional reagents, methods, and equipment in this technical field.

[0030] The following describes the synthesis method of lithium supplement I-4 as an example. The synthesis process of lithium supplement I-4 is as follows:

[0031] Synthesis Step 1: Perfluoroiodobutane (17.2 mL, 100 mmol, 1 eq) and acetonitrile (280 mL) were added to a reaction flask. NaHCO3 (16.8 g, 200 mmol, 2 eq), Na2S2O4 (43.5 g, 250 mmol, 2.5 eq), and H2O (140 mL) were added slowly in sequence under stirring at 0 °C. The mixture was then heated to room temperature and stirred for 12 h. After dilution with a certain amount of water, the mixture was extracted with ethyl acetate. The aqueous phase was extracted with a small amount of ethyl acetate. The organic phases were combined and dried over anhydrous Na2SO4. The filtrate was concentrated to dryness by rotary evaporation and then dried under vacuum to obtain a white solid sodium perfluorobutyl sulfinate (24.0 g, 73% yield). Synthesis step 2: Dissolve the sodium perfluorobutyl sulfinate obtained in step 1 in acetonitrile (100 mL), slowly add concentrated HCl (7.3 mL) while stirring at room temperature and continue stirring for 2 h, filter, dry the filtrate with anhydrous Na2SO4, and then concentrate it to dryness to obtain perfluorobutyl sulfinic acid for direct lithium lithiation reaction. Synthesis step 3: The obtained perfluorobutyl sulfinic acid was dissolved in deionized H2O (75 mL), and LiOH (1.75 g, 73 mmol) was slowly added under ice bath stirring while maintaining the temperature and stirring for 2 h; the resulting mixture was concentrated to dryness, recrystallized using EtOH / DCM mixed solvent, and then dried under reduced pressure to obtain a nearly white solid lithium supplement I-4 fluorobutyl sulfinic acid lithium (19.27 g, total yield 66.43%).

[0032] Other types of lithium supplementation synthesis routes in this application are similar to those in I-4 and will not be described again here.

[0033] The lithium replenishing agent provided in this application is added to the gel electrolyte precursor. After the gel electrolyte precursor solidifies, the lithium replenishing agent slowly replenishes lithium during battery charge-discharge cycles. The lithium replenishing agent is oxidized by the lithium-releasing positive electrode active material on the positive electrode side, generating lithium ions, sulfur dioxide, and fluorinated alkyl radicals, and releasing electrons. The reaction product, sulfur dioxide, can act as an additive, undergoing reduction and decomposition on the negative electrode side to participate in film formation. The fluorinated alkyl radicals couple to generate fluorinated alkanes. The positive electrode active material, having gained electrons, continues the battery charging reaction, releasing electrons and lithium ions, and generating active lithium on the negative electrode side.

[0034] The lithium replenishment mechanism of lithium supplements is as follows:

[0035] The lithium replenishing agent in this application slowly replenishes lithium during the battery charge-discharge cycle through the aforementioned lithium replenishment mechanism, effectively alleviating the continuous consumption of active lithium and thus significantly improving the cycle life of the battery cell. Furthermore, the lithium replenishing agent in this application generates fluorinated alkanes after lithium release. These fluorinated alkanes possess both interfacial film-forming ability and flame-retardant properties, which help improve the cycle stability and safety performance of the battery.

[0036] In another embodiment, this application provides a gel electrolyte precursor comprising the lithium supplementer as described above; Based on the total mass of the gel electrolyte precursor, the mass fraction of the lithium supplement is... The mass fraction of lithium supplement is 1.0% to 3.5%. It can be 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, or a range consisting of any two of the above numbers.

[0037] If the amount of lithium replenisher added is insufficient, it will not be able to provide enough active lithium to compensate for irreversible capacity loss during the first charge and discharge cycle; while if the amount added is too high, it is easy to reach saturation and precipitation in the electrolyte, resulting in uneven deposition on the electrode surface, increasing interfacial impedance, and thus deteriorating the battery cycle performance. Therefore, the mass fraction of the lithium replenisher should be adjusted accordingly. By controlling the concentration within the range of 1.0% to 3.5%, it is possible to avoid precipitation problems caused by excessive lithium replenishment agent, while ensuring that sufficient lithium source is released during the formation stage, thereby achieving controllable and uniform interface lithium replenishment.

[0038] In one specific embodiment, the gel electrolyte precursor further includes: a copolymer monomer, a crosslinking monomer, a gas-generating additive, and a drag-reducing additive.

[0039] Based on the total mass of the gel electrolyte precursor, the mass fraction of the copolymerizable monomers The mass fraction of comonomers is 0.3% to 1.5%. It can be 0.3%, 0.6%, 0.9%, 1.2%, 1.5%, or a range consisting of any two of the above numbers.

[0040] When the content of comonomers is too low, the cross-linking density of the gel electrolyte is too high, leading to decreased ion transport capacity, reduced conductivity, and deteriorated power performance. Conversely, when the content of comonomers is too high, it is difficult to form an effective three-dimensional network structure, resulting in insufficient gelation of the electrolyte. Therefore, the mass fraction of comonomers should be adjusted accordingly. By controlling it within the range of 0.3% to 1.5%, both gelation integrity and ionic conductivity can be balanced.

[0041] Based on the total mass of the gel electrolyte precursor, the mass fraction of cross-linked monomers The mass fraction of cross-linked monomers is 1.0% to 3.0%. It can be 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, 2.1%, 2.4%, 2.7%, 3.0%, or a range consisting of any two of the above numbers.

[0042] When the content of cross-linking monomers is too low, the cross-linking reaction between monomer molecules is insufficient, making it impossible to build a stable polymer network and hindering electrolyte gelation. Conversely, when the content of cross-linking monomers is too high, over-polymerization leads to excessively high cross-linking density in the gel, reducing electrolyte flexibility, hindering ion migration, significantly decreasing conductivity, and deteriorating the battery's rate performance. Therefore, the mass fraction of cross-linking monomers... Keeping it within the range of 1.0% to 3.0% helps to achieve a balance between gel strength and ion transport performance.

[0043] Based on the total mass of the gel electrolyte precursor, the mass fraction of the gas-generating additive is improved. The concentration is 0.5% to 3.5%. This improves the mass fraction of gas-producing additives. It can be 0.5%, 0.8%, 1.0%, 1.2%, 1.5%, 1.8%, 2.0%, 2.2%, 2.5%, 2.8%, 3.0%, 3.2%, 3.5%, or a range consisting of any two of the above numbers.

[0044] When the content of the gas-generating additive is too low, its inhibitory effect on electrolyte decomposition and interfacial side reactions is limited, and the effect on improving gas generation is not significant. Conversely, when the content of the gas-generating additive is too high, it will excessively adsorb or participate in film formation on the electrode surface, leading to a significant increase in interfacial impedance and internal resistance, thus affecting the battery's power output capability. Therefore, the mass fraction content of the gas-generating additive should be adjusted accordingly. By controlling it within the range of 0.5% to 3.5%, gas generation can be suppressed while internal resistance is prevented from worsening.

[0045] Based on the total mass of the gel electrolyte precursor, the mass fraction of drag-reducing additives The mass fraction of drag-reducing additives is 0.5% to 1.5%. It can be 0.5%, 0.6%, 0.8%, 1.0%, 1.2%, 1.5%, or a range consisting of any two of the above numbers.

[0046] When the content of drag-reducing additives is too low, the effect of reducing interfacial impedance is not significant; when the content of drag-reducing additives is too high, excessive decomposition or electrolyte oxidation side reactions can easily occur at high temperatures, leading to a significant deterioration in the high-temperature cycling performance and storage stability of the battery cell. Therefore, controlling the mass fraction of drag-reducing additives is crucial. Within the range of 0.5% to 1.5%, it helps to achieve synergistic optimization of internal resistance reduction and high-temperature stability.

[0047] In one specific embodiment, based on the total mass of the gel electrolyte precursor, the mass fraction of each component is as follows: Mass fraction of lithium supplement It ranges from 3.0% to 3.5%. mass fraction of copolymer monomers The percentage is 0.9% to 1.5%. mass fraction of cross-linked monomers It ranges from 1.0% to 2.1%; Improve the mass fraction of gas-producing additives It ranges from 1.0% to 1.5%; Mass fraction of drag-reducing additives It ranges from 0.5% to 1.0%.

[0048] In one specific embodiment, the comonomer comprises an organic olefin derivative having unsaturated carbon-carbon double bonds and functional groups. The comonomer includes at least one selected from vinylene carbonate, vinyl vinyl carbonate, acrylonitrile, N,N-dimethylacrylamide, methyl acrylate, methyl 2-methacrylate, 2,2,3,3,3-pentafluoropropyl acrylate, 2-cyanoethyl acrylate, 2-phenoxyethyl acrylate, 3-(methacryloyloxy)propyltrimethoxysilane, N,N-dimethyl(methacryloyloxyethyl)aminopropanesulfonic acid inner salt, polyethylene glycol methyl ether acrylate, polyethylene glycol methyl ether methacrylate, vinyl vinyl sulfate, vinyl vinyl sulfite, allyl methanesulfonate, phenyl alkenyl sulfonate, and diethyl alkenylphosphonate.

[0049] In one specific embodiment, the crosslinking monomer comprises an organic polyene derivative having multiple unsaturated carbon-carbon double bonds and functional groups. The crosslinking monomer includes at least one selected from ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol diacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, ethoxylated trimethylolpropane triacrylate, tripropoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, bis(trimethylolpropane)tetraacrylate, polydipentaerythritol pentaacrylate, polydipentaerythritol hexaacrylate, allyl sulfonate, and 1,3-divinyl-1,1,3,3-tetramethoxydisiloxane.

[0050] In one specific embodiment, the gas-generating additive is a conventional additive used in existing commercial electrolytes. The gas-generating additive includes at least one selected from vinyl sulfate, 1,3-propane sulpholactone, 1,4-butane sulpholactone, methylene disulfonate, vinyl disulfate, pentaerythritol dicyclic sulfate, mannitol sulfate carbonate, vinyl sulfite, and propylene sulfite. In one specific embodiment, the drag-reducing additive is a conventional additive used in existing commercial electrolytes. The drag-reducing additive includes at least one of trimethylsilyl phosphate, triethylsilyl phosphate, dimethylsilyl ethylphosphonate, dimethylsilyl propylphosphonate, dimethylsilyl 3-bistrimethylsilylaminopropylphosphonate, lithium difluorophosphate, and lithium fluorosulfonate.

[0051] It is worth noting that the gel electrolyte precursor also includes a solvent, which is a conventional solvent used in existing commercial electrolytes. The solvent includes fluorocarbonates and non-fluorocarbonates; wherein, the fluorocarbonate includes at least one of fluoroethylene carbonate, 4-trifluoromethyl ethylene carbonate, methyl (trifluoroethyl) carbonate, and di(trifluoroethyl) carbonate, and the non-fluorocarbonate includes at least one of ethylene carbonate, propylene carbonate, methyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dimethyl carbonate, dimethyl 2,5-dioxahexanoate, and diethyl 2,5-dioxahexanoate. Based on the total mass of fluorocarbonates and non-fluorocarbonates, the mass fraction A of fluoroethylene carbonate is 8% to 25%. A can be 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, or any two of the above numbers.

[0052] Excessive fluoroethylene carbonate content leads to severe deterioration in high-temperature performance. Furthermore, excessive volume expansion and contraction during the charging and discharging process of the silicon anode causes dynamic growth of the SEI film. Conversely, insufficient fluoroethylene carbonate content fails to effectively repair the SEI film, resulting in a deteriorated cycle life. Therefore, controlling the mass fraction A of fluoroethylene carbonate within the range of 8% to 25% effectively balances high-temperature safety performance with SEI film repair.

[0053] In another embodiment, this application provides a gel electrolyte prepared by gelation of a gel electrolyte precursor as described above.

[0054] In another embodiment, this application provides a semi-solid lithium-ion secondary battery, including a gel electrolyte, which is prepared by gelation of a gel electrolyte precursor as described above.

[0055] In one specific embodiment, the semi-solid-state lithium-ion secondary battery further includes a negative electrode sheet, which comprises a negative electrode material, including a silicon-based material. Specifically, the negative electrode sheet also includes a negative current collector, and the negative electrode material is disposed on at least one surface of the negative current collector.

[0056] In one specific embodiment, the mass fraction of silicon-based material is calculated based on the total mass of the negative electrode material. The mass fraction of silicon-based anode materials ranges from 10.0% to 30.0%. It can be 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, or a range consisting of any two of the above numbers.

[0057] In one specific embodiment, the mass fraction of silicon-based material It is 15% to 25%; more specifically, the mass fraction of silicon-based materials. It is 15% to 20%.

[0058] In one specific embodiment, the silicon-based material comprises at least one of elemental silicon, silicon-carbon composites, silicon oxides, silicon nitrides, and silicon alloys.

[0059] In one specific embodiment, the semi-solid-state lithium-ion secondary battery further includes a positive electrode sheet. The positive electrode sheet comprises a positive current collector and a positive active material layer disposed on at least one surface of the positive current collector and comprising a lithium nickel cobalt manganese oxide. In the lithium nickel cobalt manganese oxide, based on the molar amount of metal elements other than lithium, the molar percentage content B of nickel element satisfies: B ≥ 70%. B can be 70%, 75%, 78%, 80%, 82%, 88%, 90%, 92%, or a range consisting of any two of the above numbers.

[0060] In one specific embodiment, the semi-solid-state lithium-ion secondary battery further includes a separator. The separator comprises a base film and a solid electrolyte coating coated on the separator, the solid electrolyte coating having a thickness of 2 μm to 6 μm.

[0061] The solid electrolyte coating contains at least one of lithium aluminum titanium phosphate (LATP), lithium aluminum germanium phosphate (LAGP), lithium lanthanum titanate (LLTO), and lithium lanthanum zirconate (LLZO).

[0062] It is worth mentioning that existing high-energy-density semi-solid-state batteries generally adopt a high-nickel ternary cathode, a high-content silicon / graphite anode, and a gel electrolyte system. However, their mass production process still faces many challenges: On the one hand, the ionic conductivity decreases after the electrolyte gels, resulting in sluggish lithium-ion transport kinetics, insufficient power performance, intensified concentration polarization, and a significant increase in DC internal resistance (DCR). On the other hand, the cycle life is limited due to the drastic volume expansion of the silicon-based anode during charging and discharging, which causes electrode structure rupture and repeated breakage and regeneration of the SEI film. In the gel electrolyte, the insufficient fluidity of the components makes it difficult for the SEI film to be effectively repaired, resulting in continuous consumption of active lithium, which further aggravates irreversible capacity decay and polarization accumulation.

[0063] In other words, the current semi-solid-state battery system still falls short in terms of overall performance in terms of energy density, cycle stability, and rate performance, making it difficult to meet the practical application requirements of high-performance batteries. To address these issues, this application proposes the following technical solution: In one specific embodiment, the semi-solid-state lithium-ion secondary battery satisfies the following formula: ; in, , It can be any one of the following values: 10.0, 11.6, 13.3, 15.5, or 16.1. It can be any one of 16.8, 17.4, 20.9, or 25.0.

[0064] In one specific embodiment, the semi-solid-state lithium-ion secondary battery satisfies the following formula: .

[0065] In one specific embodiment, the semi-solid-state lithium-ion secondary battery satisfies the following formula: .

[0066] In one specific embodiment, the semi-solid-state lithium-ion secondary battery satisfies the following formula: .

[0067] In one specific embodiment, the semi-solid-state lithium-ion secondary battery satisfies the following formula: .

[0068] In one specific embodiment, the semi-solid-state lithium-ion secondary battery satisfies the following formula: .

[0069] In one specific embodiment, the semi-solid-state lithium-ion secondary battery satisfies the following formula: .

[0070] The semi-solid lithium-ion secondary battery of this application includes a novel lithium replenishing agent. The lithium replenishing agent slowly replenishes lithium during charge-discharge cycles after the gel electrolyte solidifies, thereby improving the cycle life of the cell. Moreover, after the lithium is released, the lithium replenishing agent forms a polyfluorinated alkane derivative, which has film-forming and flame-retardant properties. This application also uses copolymer monomers and cross-linked monomers to construct a three-dimensional polymer structure, which effectively improves the thermal stability of the gel electrolyte and improves the safety performance of the cell.

[0071] This application improves the initial DCR at room temperature, cycle life, high-temperature gas generation, and safety performance of high-energy-density semi-solid-state batteries by controlling the mass fractions of copolymerizable monomers, crosslinking monomers, lithium supplementers, gas generation improvement additives, drag reduction additives, and the mass fraction of silicon-based anode materials in the anode active material to satisfy specific relationships.

[0072] The present application will be further described below with reference to embodiments and comparative examples. Unless otherwise specified, the reagents, methods and equipment used in this application are conventional reagents, methods and equipment in this technical field.

[0073]

Example 1

[0074] (2) Preparation of negative electrode sheet The negative electrode active material, graphite, silicon carbide, conductive agent, and binder were mixed uniformly at a mass ratio of 76:20:1:3 to obtain the negative electrode material. Based on the total mass of the negative electrode material, the mass fraction of silicon carbide was 20%. The negative electrode material was uniformly dispersed in deionized water to form a black slurry, which was then coated on both sides of a copper foil. After baking, rolling, and cutting, the negative electrode sheet was obtained, with a compaction density of 1.65 g / cm³ for the negative electrode active material layer. 3 The compaction density of the negative electrode active material layer is controlled by the electrode manufacturing process, specifically by the electrode coating weight and the electrode roll forming thickness parameters.

[0075] (3) Preparation of gel electrolyte precursor solution At room temperature, in an argon-filled glove box (H2O < 1 ppm, O2 < 1 ppm), DEC (diethyl carbonate), EMC (ethyl methyl carbonate), PC (propylene carbonate), and FEC (fluoroethylene carbonate) were mixed uniformly in a mass ratio of 25:43:20:12. The mixture was then dehydrated using a 4 Å molecular sieve to obtain a mixed solvent. 12.5% ​​of the total mass of the gel electrolyte precursor, lithium salt LiPF6 (lithium hexafluorophosphate), was added to the prepared mixed solvent in batches while continuously stirring and cooling to ensure that the temperature rise in the mixed solvent did not exceed 2 °C. Lithium salt was continuously added, followed by 1.5% of the total mass of the gel electrolyte precursor, lithium salt LiFSI (lithium bisfluorosulfonylimide). LiFSI was added in multiple batches to prepare a colorless and transparent liquid.

[0076] Add 0.9 wt% of the copolymer methyl 2-methacrylate, 2.1 wt% of the crosslinking monomer trimethylolpropane trimethacrylate, 0.06 wt% of the initiator azobisisobutyronitrile (AIBN), 3.5 wt% of the lithium supplement lithium trifluoromethyl sulfinate (I-1), 0.7 wt% of the gas-producing additive vinyl sulfate (DTD), 0.3 wt% of the gas-producing additive 1,3-propane sulcolone (PS), 0.5 wt% of the drag-reducing additive tris(trimethylsilyl) phosphate (TMSP), and 0.3 wt% of the drag-reducing additive lithium difluorophosphate (LiPO2F2) to a colorless and transparent liquid, and stir until homogeneous to obtain a gel electrolyte precursor solution.

[0077] (4) Assembly of lithium-ion semi-solid soft-pack batteries The positive electrode, the PI separator with ceramic coating, and the negative electrode are stacked in sequence, so that the PI separator covers the positive and negative electrode. After stacking, a bare cell is obtained. The bare cell is encapsulated in an aluminum-plastic film and baked at high temperature until the moisture content reaches the standard. Then, 23g of the prepared gel electrolyte precursor solution is injected. After sealing and standing to fully wet, it is placed in a 60℃ oven and heated for 12 hours to complete gelation. After formation, high temperature aging, hot pressing, secondary sealing, and capacity testing, a secondary lithium-ion semi-solid soft-pack battery is obtained.

[0078]

Example 2

[0079] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0080]

Example 3

[0081] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0082]

Example 4

[0083] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0084]

Example 5

[0085] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0086]

Example 6

[0087] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0088]

Example 7

[0089] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0090]

Example 8

[0091] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0092]

Example 9

[0093] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0094]

Example 10

[0095] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0096]

Example 11

[0097] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0098]

Example 12

[0099] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0100]

Example 13

[0101] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0102]

Example 14

[0103] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0104]

Example 15

[0105] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0106]

Example 16

[0107] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0108]

Example 17

[0109] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0110]

Example 18

[0111] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0112]

Example 19

[0113] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0114]

Example 20

[0115] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0116]

Example 21

[0117] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0118]

Example 22

[0119] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0120]

Example 23

[0121] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0122]

Example 24

[0123] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0124]

Example 25

[0125] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0126]

Example 26

[0127] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0128]

Example 27

[0129] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0130]

Example 28

[0131] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0132]

Example 29

[0133] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0134]

Example 30

[0135] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0136]

Example 31

[0137] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0138]

Example 32

[0139] The remaining components and preparation steps in this embodiment are the same as in Example 1.

[0140] Comparative Example 1 This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that: In the preparation of the gel electrolyte precursor solution, the mass fraction of the copolymer methyl 2-methacrylate was 0, and the mass fraction of the crosslinking monomer trimethylolpropanetrimethacrylate was 3.0 wt%.

[0141] The remaining components and preparation steps in this comparative example are the same as in Example 1.

[0142] Comparative Example 2 This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that: In the preparation of the gel electrolyte precursor solution, the mass fraction of the copolymeric monomer methyl 2-methacrylate is 0.3 wt%, and the mass fraction of the crosslinking monomer trimethylolpropanetrimethacrylate is 2.7 wt%.

[0143] The remaining components and preparation steps in this comparative example are the same as in Example 1.

[0144] Comparative Example 3 This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that: In the preparation of the gel electrolyte precursor solution, the mass fraction of the copolymeric monomer 2-methyl methacrylate is 1.8 wt%, and the mass fraction of the crosslinking monomer trimethylolpropanetrimethacrylate is 1.0 wt%.

[0145] The remaining components and preparation steps in this comparative example are the same as in Example 1.

[0146] Comparative Example 4 This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that: The negative electrode active material, graphite, silicon carbon, conductive agent and binder are mixed evenly in a mass ratio of 86:10:1:3 to obtain the negative electrode material. Based on the total mass of the negative electrode material, the mass fraction of silicon carbon is 10%.

[0147] The remaining components and preparation steps in this comparative example are the same as in Example 1.

[0148] Comparative Example 5 This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that: This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that in the preparation of the gel electrolyte precursor solution, the mass fraction of the gas-generating additive vinyl sulfate (DTD) is 2.5 wt%, and the mass fraction of the gas-generating additive 1,3-propane sulpholactone (PS) is 1.5 wt%.

[0149] The remaining components and preparation steps in this comparative example are the same as in Example 1.

[0150] Comparative Example 6 This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that: This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that in the preparation of the gel electrolyte precursor solution, the mass fraction of drag-reducing additive tris(trimethylsilyl) phosphate (TMSP) is 1.0 wt%, and the mass fraction of drag-reducing additive lithium difluorophosphate (LiPO2F2) is 1.0 wt%.

[0151] The remaining components and preparation steps in this comparative example are the same as in Example 1.

[0152] Comparative Example 7 This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that: This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that the mass fraction of the copolymer monomer 2-methyl methacrylate in the preparation of the gel electrolyte precursor solution is 0.3 wt%, and it does not contain lithium supplementation agent.

[0153] The remaining components and preparation steps in this comparative example are the same as in Example 1.

[0154] Comparative Example 8 This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that: This comparative example provides a method for preparing a secondary lithium-ion semi-solid-state battery. The difference between this comparative example and Example 1 is that the mass fraction of lithium trifluoromethyl sulfinate, the lithium replenishing agent, is 0.5 wt%.

[0155] The remaining components and preparation steps in this comparative example are the same as in Example 1.

[0156] The specific parameters used in Examples 1 to 32 and Comparative Examples 1 to 8 are shown in Table 1.

[0157] Table 1

[0158] The performance of the secondary lithium-ion semi-solid-state pouch batteries obtained in the above embodiments and comparative examples was tested. The specific test items, test methods, and results are shown below: 1. Initial DCR test at room temperature At 25±2℃, the secondary lithium-ion semi-solid soft-pack batteries obtained in the examples and comparative examples were charged to 4.25V at a constant current of 0.5C, then charged at a constant voltage until the current became 0.05C, then discharged at a current of 1C for 30 minutes to adjust to 50% SOC, and then pulsed discharged at a constant current of 2.5C for 10 seconds and then charged for 10 seconds. The initial DCR at room temperature was calculated as (voltage before pulse discharge - voltage after pulse discharge) / discharge current. The results are shown in Table 2.

[0159] 2. Room temperature cycling performance test At 25±2℃, the secondary lithium-ion semi-solid-state pouch batteries obtained in the examples and comparative examples were subjected to charge-discharge cycle tests at a charge-discharge current of 0.5C / 1C within a voltage range of 2.5~4.25V. The discharge capacity of the battery in the first cycle and the discharge capacity after 500 cycles at room temperature were recorded. The capacity retention rate after 500 cycles at room temperature = discharge capacity after 500 cycles / discharge capacity in the first cycle * 100%. The recorded data are shown in Table 2.

[0160] 3. High-temperature gas production performance test At 25±2℃, the secondary lithium-ion semi-solid soft-pack batteries obtained in the examples and comparative examples were charged at a constant current of 0.5C to 4.25V, and then charged at a constant voltage until the current became 0.05C, so that the cell reached a fully charged state. The volume of the fully charged cell before storage was measured and recorded as V0. The cell was then placed in an oven at 60±2℃. After 30 days, it was taken out and cooled to room temperature. The volume of the cell after storage was measured and recorded as V1. The high-temperature storage volume expansion rate = (V1-V0) / V0*100%. The recorded data are shown in Table 2.

[0161] 4. Hot Box Performance Test At 25±2℃, the secondary lithium-ion semi-solid soft-pack batteries obtained in the examples and comparative examples were charged to 4.25V at a constant current of 0.5C, and then charged to 0.05C at a constant voltage to bring the cells to a fully charged state. The fully charged cells were placed in a temperature chamber, and the temperature of the temperature chamber was increased from room temperature to 130℃ at a rate of 5℃ / min and held at that temperature for 30min. Then, the temperature was gradually increased to 135℃, 140℃, 145℃, and 145℃ at a rate of 5℃ / min, and held at each temperature for 30min. The results of the hot chamber test were recorded as shown in Table 2.

[0162] Table 2 Performance test results of the pouch cells prepared in Examples 1-32 and Comparative Examples 1-8

[0163] From the data in Table 2 above, we can conclude that: (a) In Examples 1-5 and Comparative Examples 1-3, the mass fractions of the copolymeric monomer and the crosslinking monomer were adjusted to make... The data obtained from Examples 1-5 and Comparative Examples 1-3 show that they have different numerical values. Examples 1 to 5 are in When the value is in the range of 11.6 to 20.9, the battery exhibits a low initial DCR at room temperature (12.1 mΩ to 15.1 mΩ) and excellent capacity retention after 500 cycles at room temperature (92.6% to 94.2%), while the high-temperature storage volume expansion rate is controlled within the range of 14.0% to 16.2%. This indicates that the process parameters within this range are beneficial to improving the electrochemical stability and conductivity of the battery.

[0164] Further analysis shows that when When the temperature is preferably in the range of 11.6 to 16.8 (Examples 1, 3, 4, 5), the overall performance of the battery is better: the room temperature DCR is further reduced to 12.1 mΩ to 14.5 mΩ, the cycle retention rate is maintained above 93.2%, and the hot box test is passed (140℃ or 130℃ / 30min), showing better thermal stability and structural integrity.

[0165] In contrast, Comparative Example 1 and Comparative Example 2 The values ​​were 36.5 and 26.9, respectively, exceeding the above range, leading to an increase in the initial DCR at room temperature and a decrease in cycle retention; while in Comparative Example 3... Although it exhibits good cycling performance at the low value end (9.5), its high-temperature storage volume expansion rate reaches 16.1%, which is close to the 16.2% of Example 5.

[0166] As its value increases, both the initial DCR at room temperature and the cycle retention rate will deteriorate. This is mainly because the increased content of cross-linked monomers leads to a decrease in the conductivity of the gel electrolyte, insufficient interfacial stability, and deterioration of concentration polarization, which in turn leads to a deterioration in the initial DCR at room temperature and cycle performance. When the value decreases, the volume expansion rate of high-temperature storage and the performance of the hot box deteriorate. This is mainly because when the content of copolymer monomers increases, the cross-linking of the resulting gel polymer is too low, and the thermal stability of the gel electrolyte is insufficient, which leads to the deterioration of high-temperature gas generation and hot box performance.

[0167] Therefore, a comprehensive assessment shows that, Good overall performance can be achieved in the range of 11.6 to 20.9, while... When controlled within the range of 11.6 to 16.8 (corresponding to a mass fraction of 0.9% to 1.5% for copolymer monomers and 1.0% to 2.1% for crosslinked monomers), the battery achieves a better balance between power characteristics, cycle life, safety, and dimensional stability.

[0168] (II) Between Examples 1 and Examples 6-9 With all values ​​set to 16.8, only the type of copolymer monomer was adjusted, while other preparation parameters remained the same.

[0169] As can be seen from the test results in Table 2, the introduction of different copolymer materials has little impact on the overall performance of the battery, and all embodiments show excellent and similar comprehensive performance.

[0170] Specifically, the capacity retention rate of Examples 1 and 6-9 after 500 cycles at room temperature was stable between 93.1% and 93.8%, and the volume expansion rate during high-temperature storage was distributed in the range of 13.4% to 14.5%. All of them passed the 140℃ / 30min hot box test without thermal runaway, indicating that the battery has good cycle stability, dimensional controllability and thermal safety.

[0171] While there were some fluctuations in the initial DCR at room temperature (14.5 mΩ ~ 16.7 mΩ), the differences were relatively limited, and all values ​​remained at a low level, not significantly affecting the overall electrochemical performance. Example 1 exhibited the lowest DCR (14.5 mΩ), which is related to the fact that its copolymer monomer was more conducive to forming a uniform and stable network. Examples 8 and 9 had slightly higher DCRs, but also lower corresponding high-temperature storage volume expansion rates, resulting in better overall performance.

[0172] Overall, in Under the condition of 16.8, different types of copolymer monomers can achieve excellent and stable battery performance.

[0173] (III) Between Example 1 and Examples 10-11 With all values ​​set to 16.8, only the type of cross-linking monomer was adjusted, while other preparation parameters remained consistent.

[0174] As can be seen from the data in Table 2, the introduction of different types of cross-linked monomers has minimal impact on the overall performance of the battery, and all embodiments exhibit highly consistent and excellent comprehensive performance.

[0175] Specifically, the capacity retention rates after 500 cycles at room temperature in Examples 1, 10, and 11 were very close, at 93.2%, 93.5%, and 93.4%, respectively. This indicates that different cross-linked monomers can effectively maintain electrode structural stability and interfacial compatibility and suppress capacity decay during long-term cycling. Meanwhile, all samples successfully passed the 140℃ / 30min hot box test without thermal runaway, demonstrating good thermal stability and safety performance. Regarding the high-temperature storage volume expansion rate, the values ​​ranged from 14.0% to 14.6%, with minimal differences.

[0176] Regarding the initial DCR at room temperature, Example 1 showed 14.5 mΩ, Example 10 showed 15.8 mΩ, and Example 11 showed 15.1 mΩ. All examples were at a low level, with the maximum difference being less than 1.3 mΩ, and did not have a substantial impact on the battery's power performance.

[0177] In summary, With the value fixed at 16.8, when only the type of cross-linked monomer is adjusted, all key performance indicators of the battery remain highly consistent, exhibiting excellent and stable electrochemical and safety characteristics.

[0178] (iv) Examples 1, 12-14, and Comparative Example 8: The mass fraction of the lithium supplement was adjusted to... They have different values. The higher the mass fraction of the lithium supplement, the better. The higher the value, the better.

[0179] In Comparative Examples 8, Examples 12-14, and Example 1, the mass fraction of the lithium supplement gradually increased from 0.5% (Comparative Example 8) to 3.5% (Example 1), thereby making... The initial DCR at room temperature gradually increased from 8.3 (Comparative Example 8) to 16.8 (Example 1). The changes in the initial DCR at room temperature were not significant in the comparative example and each example, remaining between 14.3 mΩ and 14.5 mΩ, indicating that the change in the lithium supplement content had little effect on the initial DCR at room temperature.

[0180] However, the capacity retention rate after 500 cycles at room temperature shows a trend of... The trend of increasing and improving: when When the value is 8.9, the cycle retention rate is 90.8%; when When the value is 10.3, the cycle retention rate is 91.2%; when When it increases to 12.9, it rises to 92.0%; When further increased to 15.5 and 16.8, the efficiency reached 92.7% and 93.2%, respectively. This indicates that appropriately increasing the lithium replenisher content and the amount of active lithium released by the lithium replenisher helps to enhance the battery's cycle performance, thereby suppressing capacity decay during cycling.

[0181] Meanwhile, the volume expansion rate of high-temperature storage increases with The rate of increase gradually increased from 13.1% in Example 12 to 14.5% in Example 1. The high-temperature storage volume expansion rate of the batteries in Examples 1, 12-14 was within an acceptable range, and all of them passed the 140°C / 30min hot box test without thermal runaway, indicating that the batteries have good thermal safety performance under all conditions.

[0182] In summary, all other things being equal, adjusting the content of the lithium supplement can affect... Optimization is particularly crucial for improving cycle life. Although the lower While (e.g., 10.3) can achieve smaller volume expansion, the cycle retention rate is relatively low; while... When the energy density is increased to the 15.5~16.8 range, the battery significantly improves long-term cycle performance while maintaining good dimensional stability. Therefore, considering both cycle life and volume expansion, A better overall performance balance can be achieved when the concentration is preferably in the range of 15.5 to 16.8 (corresponding to a mass fraction of 3.0% to 3.5% for the lithium supplement).

[0183] (v) Between Example 1 and Examples 15-18 With all values ​​set to 16.8, only the type (structural formula) of the lithium replenishing agent was adjusted, while other preparation parameters remained consistent.

[0184] The initial DCR at room temperature for Examples 1 and 15-18 remained within the range of 14.5 mΩ to 15.5 mΩ, with minimal differences, indicating that the effects of different lithium replenishment agents on the initial DCR at room temperature are basically consistent. Regarding cycle performance, the capacity retention rate after 500 cycles at room temperature for all examples was no less than 92.2%, with Example 1 reaching 93.2%, while the remaining examples fluctuated between 92.2% and 92.9%, showing similar degradation trends across the examples.

[0185] It is worth noting that, When the values ​​are the same, the capacity retention rate of the lithium replenishing agent with different structures is higher in Example 1 after 500 cycles at room temperature. The lithium replenishing agent structure I-1 is used in Example 1 mainly because when using the same mass of lithium replenishing agent, the Li molar amount of structure I-1 is the highest, which has a better effect on improving cycle life. Therefore, the preferred structure of the lithium replenishing agent is structure I-1.

[0186] Regarding the volume expansion rate during high-temperature storage, the values ​​for each embodiment ranged from 13.7% to 14.5%, with Embodiments 16 and 18 exhibiting lower expansion rates (13.7% and 13.8%, respectively). All embodiments passed rigorous hot-box testing, with Embodiment 16 even passing a higher temperature test at 145°C for 30 minutes, while the others passed at 140°C for 30 minutes without thermal runaway, further validating the excellent thermal stability and safety of the battery under different component selections.

[0187] exist With a constant lithium content of 16.8, changing only the type of lithium replenisher resulted in highly consistent key battery performance characteristics, including excellent cycle life, internal resistance, expansion behavior, and thermal safety. This indicates that different types of lithium replenishers exhibit good versatility and stability within the current system, with minimal performance differences.

[0188] (vi) Examples 1, 19-22, and Comparative Example 5 improved the gas-producing additive by adjusting its mass fraction. They have different values.

[0189] when When varying within the range of 11.0 to 22.9, the initial DCR at room temperature remained at a low level (14.0 mΩ to 15.6 mΩ), with Example 21 ( =22.9) and Example 19 ( =18.8) exhibited the lowest DCR (14.0 and 14.2 mΩ, respectively), while Example 22 (11.0) had a slightly higher DCR (15.6 mΩ) at the lower value.

[0190] Regarding cycle performance, the capacity retention rate after 500 cycles at room temperature in all embodiments was higher than 92.6%, with minimal differences. Among them, Example 20 ( =13.3) and Example 1 ( =16.8) reached 93.5% and 93.2% respectively, showing better performance; while other groups were slightly lower, remaining at 92.6% ~ 92.9%, indicating Values ​​in the range of 13.3 to 16.8 are more conducive to improving long-term cycle stability.

[0191] High-temperature storage volume expansion rate with The increase shows an upward trend: Example 22 ( =11.0) and Example 20 ( The expansion rates of Example 19 (=13.3) were 13.4% and 14.0%, respectively. =18.8) and Example 21 ( =22.9) reached 15.7% and 15.8% respectively. All embodiments successfully passed the 140℃ / 30min hot box test without thermal runaway, demonstrating good thermal safety.

[0192] Comparative Example 5 The value was 7.3. Although Comparative Example 5 had a lower high-temperature storage volume expansion rate (11.2%), its initial DCR at room temperature was 20.5 mΩ, which was significantly higher than that of the Example. Moreover, the capacity retention rate of Comparative Example 5 after 500 cycles at room temperature was 91.4%, which was lower than that of the Example. Therefore, the overall performance of the battery obtained by Comparative Example 5 was not good.

[0193] When its value increases, the volume expansion rate of high-temperature storage deteriorates, mainly due to the reduction in the mass fraction of the gas-generating additive, which results in limited inhibition of electrolyte decomposition and interfacial side reactions, and the effect of improving gas generation is not significant. When the value decreases, the initial DCR and cycle retention rate at room temperature will both deteriorate. This is mainly due to the increase in the mass fraction of the gas-generating additive. The mass fraction of the gas-generating additive will be over-adsorbed on the electrode surface or participate in film formation, resulting in a significant increase in interfacial impedance and internal resistance, which will affect the power output capability of the battery.

[0194] In conclusion, The value of has a significant regulatory effect on battery performance. When When the value is too low (e.g., 11.0), although the volume expansion rate is small during high-temperature storage, the initial DCR at room temperature is high, affecting power performance; when When the value is too high (e.g., 22.9), although the initial DCR at room temperature is relatively low, the volume expansion rate during high-temperature storage increases significantly. In contrast, Within the range of 13.3 to 16.8 (corresponding to a mass fraction of 1.0% to 1.5% for the gas-generating additive), the battery achieves a better balance between cycle retention, internal resistance, and volume expansion, resulting in superior overall performance.

[0195] (vii) Between Example 1 and Examples 23-25 With all values ​​set to 16.8, only the type of gas-producing additive was adjusted, while other preparation parameters remained consistent.

[0196] The initial DCR at room temperature for each embodiment ranged from 14.5 mΩ to 15.8 mΩ, with minimal differences. Regarding cycle performance, the capacity retention rate after 500 cycles at room temperature for each embodiment was no less than 92.4%, reaching a maximum of 93.2% (Example 1). The differences between groups were minimal, indicating that different types of additives to improve gas production could effectively maintain battery cycle performance.

[0197] Regarding the volume expansion rate during high-temperature storage, the values ​​for each embodiment ranged from 13.2% to 15.4%. All embodiments successfully passed the 140℃ / 30min hot chamber test without thermal runaway, fully verifying their good thermal stability and safety.

[0198] Therefore, in fixed Under the condition of 16.8, when only the type of gas-generating additive is changed, the key performance indicators of the battery (initial DCR at room temperature, 500-cycle capacity at room temperature, volume expansion rate at high temperature and thermal safety performance) remain within a good and stable range.

[0199] (viii) Examples 1, 26-28, and Comparative Example 6: By adjusting the mass fraction of the drag-reducing additive, They have different values.

[0200] along with The initial DCR at room temperature gradually increased from 16.1 (Example 26) to 18.7 (Example 28), decreasing from 15.0 mΩ to 13.3 mΩ, indicating a higher DCR. This helps reduce the initial internal resistance of the battery.

[0201] Regarding capacity retention after 500 cycles at room temperature, as As the temperature rises, cycle performance gradually decreases: Example 26 ( =16.1) and Example 1 ( =16.8) reached 93.3% and 93.2% respectively, showing excellent performance; Example 27 ( =17.4) is 92.8%; while Example 28 ( =18.7) further decreased to 91.9%, indicating that it was too high. This value leads to faster capacity decay.

[0202] High-temperature storage volume expansion rate with The percentage increased significantly: from 13.9% in Example 26 to 15.9% in Example 28, showing a significant increase.

[0203] It is worth noting that all embodiments passed the 140℃ / 30min hot chamber test without thermal runaway, indicating that within this experimental range, different control... The battery still has basic thermal safety redundancy.

[0204] Comparative Example 6 Although Comparative Example 6 has a lower high-temperature storage volume expansion rate (13.5%), its initial DCR at room temperature is 18.9 mΩ, which is significantly higher than that of the Examples. Furthermore, the capacity retention rate of Comparative Example 5 after 500 cycles at room temperature is 92.5%, which is lower than that of Examples 1, 26, and 27. Therefore, the overall performance of the battery obtained by Comparative Example 6 is not good.

[0205] When its value increases, the cycle retention rate and high-temperature storage volume expansion rate deteriorate, mainly due to the increase in the mass fraction of drag-reducing additives, which are prone to excessive decomposition at high temperatures or to trigger side reactions of electrolyte oxidation, resulting in a significant deterioration in the high-temperature cycle performance and storage stability of the cell. When the value decreases, the initial DCR at room temperature will deteriorate, mainly due to the reduction in the mass fraction of drag-reducing additives, thus the effect of reducing interfacial impedance is not obvious.

[0206] Comprehensive analysis shows that, Within the range of 16.1 to 17.4 (corresponding to a mass fraction of drag-reducing additive of 0.5% to 1.0%), the battery achieved a better balance between cycle life, volume expansion, and internal resistance, especially with Example 1 (16.8) and Example 26 (16.1) showing better overall performance. When the value exceeds 17.4 (as in Example 28), although the initial DCR at room temperature decreases further, the cycle retention rate and volume expansion deteriorate significantly, resulting in a decline in overall performance. Therefore, it is preferable to... Within the range of 16.1 to 17.4.

[0207] (ix) Between Example 1 and Example 29 With all values ​​set to 16.8, only the type of drag-reducing additive was adjusted, while other preparation parameters remained consistent.

[0208] The initial DCR at room temperature for Examples 1 and 29 are very close, with Example 1 at 14.5 mΩ and Example 29 at 14.2 mΩ, showing minimal difference. This indicates that the different drag-reducing additives did not adversely affect the power performance of the battery.

[0209] In terms of cycle performance, Example 1 had a capacity retention rate of 93.2% after 500 cycles at room temperature, and Example 29 had a retention rate of 93.0%, both of which are at an excellent level, showing that the long-term cycle reliability of the two is highly consistent.

[0210] Although the high-temperature storage volume expansion rate of Example 29 was slightly higher, it was still within an acceptable range and did not significantly affect its thermal safety performance. Both Examples 1 and 29 successfully passed the 140°C / 30min hot box test without thermal runaway, indicating that the battery still has sufficient safety redundancy even under high expansion conditions.

[0211] In summary, in a fixed In the system with a strength of 16.8, when only the type of additive was changed, the electrochemical performance, cycle stability and thermal safety of the battery did not change significantly, and all indicators remained at an excellent level.

[0212] (X) Examples 1 and 30-32: By adjusting the mass fraction of silicon-carbon material, They have different values.

[0213] In Example 32 =11.2, passed the hot box test (135℃ / 30min), the capacity retention rate after 500 cycles at room temperature was 90.1%, the lowest among Examples 1 and Examples 30-32, and the high-temperature storage volume expansion rate reached 18.5%, significantly higher than other groups. Meanwhile, the initial DCR at room temperature in Example 32 was relatively high (15.2 mΩ).

[0214] when When the values ​​were increased to 16.8 (Example 1) and 22.5 (Example 31), the cycle performance was excellent, reaching 93.2% and 93.0% respectively, and the initial DCR at room temperature was low (14.5 and 14.2 mΩ respectively), indicating that the battery performance was better in this range.

[0215] Comparative Example 4 ( Although it has a lower initial DCR at room temperature (14.1 mΩ) and a lower high-temperature storage volume expansion rate (10.2%), its cycle retention rate is only 92.5%, which is not significantly better than Example 1.

[0216] Furthermore, the hot box test results showed that, except for Comparative Example 4 and Examples 1 to 31, which all passed 140℃ / 30min, Example 32 only passed 135℃ / 30min, indicating that Example 32 has relatively weak thermal stability.

[0217] when Within the range of 16.8 to 22.5, the battery achieves a better balance between cycle retention, internal resistance, volume expansion, and thermal safety, resulting in superior overall performance. This is particularly evident in Example 1 (…). =16.8) While maintaining good expansion control, it also has high cycle stability and strong thermal safety, showing better overall performance.

[0218] In Comparative Example 4, Example 1, and Examples 30-32, as the mass fraction of silicon-carbon material gradually increased from 10% (Comparative Example 4) to 30% (Example 32), the initial DCR of the battery at room temperature showed a slow upward trend, increasing from 14.1 mΩ to 15.2 mΩ. This change is mainly attributed to the poor conductivity of silicon-based materials and the large volume change during cycling, which leads to a decrease in interface stability and thus increases charge transport resistance.

[0219] In terms of cycle performance, when the mass fraction of silicon-carbon material is 20% (Example 1), the capacity retention rate after 500 cycles at room temperature reaches 93.2%, which is the highest among all battery samples. When the silicon-carbon material content increases to 25% (Example 30) and 30% (Example 32), the cycle retention rate decreases to 92.1% and 90.1%, respectively. This indicates that excessive silicon content will exacerbate material pulverization, repeated rupture and regeneration of the SEI film, resulting in loss of active material and depletion of lithium inventory, thereby accelerating capacity decay.

[0220] Meanwhile, the volume expansion rate of high-temperature storage increases significantly with the increase of silicon-carbon material content: the volume expansion rate of high-temperature storage is 10.2% when the mass fraction of silicon-carbon material is 10%, and 18.5% when the mass fraction of silicon-carbon material is 30%. This is due to the huge volume change of silicon-based materials during charging and discharging.

[0221] The hot box test results further verified the above trend: Example 32, which contained 30% silicon-carbon material, only passed the 135℃ / 30min test, while the other samples all passed the 140℃ / 30min test without thermal runaway. This indicates that high silicon content reduces the thermal stability of the electrode structure, increases the severity of side reactions and the risk of gas generation at high temperatures, thereby affecting the safety boundary of the battery.

[0222] In summary, the mass fraction of silicon-carbon materials has a crucial impact on battery performance. Batteries with a silicon material mass fraction in the range of 15% to 25% exhibit superior overall performance. More specifically, with a silicon material mass fraction of 15% to 20%, the battery maintains low internal resistance while also possessing excellent cycle retention (≥93.0%), controllable volume expansion (≤14.5%), and good thermal safety (passing 140℃ / 30min).

[0223] In summary, based on the above embodiments and comparative examples, this application can improve the initial DCR at room temperature, cycle life, high-temperature gas generation, and safety performance of high-energy-density semi-solid-state batteries by optimizing the structure of the lithium replenishing agent and controlling the mass fractions of copolymeric monomers, crosslinking monomers, lithium replenishing agents, gas generation improvement additives, drag reduction additives, and the mass fraction of silicon-based anode materials in the anode active material to satisfy specific relationships.

[0224] Although preferred embodiments have been described in this application, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of this application.

[0225] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A lithium supplement, characterized in that, The lithium supplement includes compounds as shown in Formula I and / or Formula II: ； Where R is C i F (2i+1) O j , 1≤i≤12, 0≤j≤6; X is C m F 2m O n , 1≤m≤8, 0≤n≤4.

2. The lithium supplement agent as described in claim 1, characterized in that, The lithium supplement includes compounds with the following structural formula: 、 、 At least one of them; Preferably, the lithium supplement is .

3. A gel electrolyte precursor, characterized in that, Includes the lithium replenishing agent as described in claim 1 or 2; Based on the total mass of the gel electrolyte precursor, the mass fraction of the lithium supplement is... It ranges from 1.0% to 3.5%.

4. The gel electrolyte precursor as described in claim 3, characterized in that, The gel electrolyte precursor also includes: copolymerizable monomers, cross-linked monomers, gas-generating additives, and drag-reducing additives; Based on the total mass of the gel electrolyte precursor, the mass fraction of each component is as follows: The mass fraction of the comonomer The percentage is 0.3% to 1.5%. The mass fraction of the crosslinked monomer The percentage is 1.0% to 3.0%; The mass fraction of the gas-producing additive The percentage is 0.5% to 3.5%; The mass fraction of the drag-reducing additive It ranges from 0.5% to 1.5%.

5. The gel electrolyte precursor as described in claim 4, characterized in that, Based on the total mass of the gel electrolyte precursor, the mass fraction of each component is as follows: The mass fraction of the lithium supplement It ranges from 3.0% to 3.5%. The mass fraction of the comonomer The percentage is 0.9% to 1.5%. The mass fraction of the crosslinked monomer It ranges from 1.0% to 2.1%; The mass fraction of the gas-producing additive It ranges from 1.0% to 1.5%; The mass fraction of the drag-reducing additive It ranges from 0.5% to 1.0%.

6. A gel electrolyte, characterized in that, It is prepared by gelation of the gel electrolyte precursor as described in any one of claims 3 to 5.

7. A semi-solid-state lithium-ion secondary battery, characterized in that, Includes a gel electrolyte, which is prepared by gelation of the gel electrolyte precursor as described in claim 4 or 5.

8. The semi-solid-state lithium-ion secondary battery as described in claim 7, characterized in that, The semi-solid lithium-ion secondary battery also includes a negative electrode sheet, which includes a negative electrode material, and the negative electrode material includes a silicon-based material.

9. The semi-solid-state lithium-ion secondary battery as described in claim 8, characterized in that, Based on the total mass of the negative electrode material, the mass fraction of the silicon-based material is... The percentage is 10.0% to 30.0%; Preferably, the mass fraction of the silicon-based material It ranges from 15% to 25%; Preferably, the mass fraction of the silicon-based material It is 15% to 20%.

10. The semi-solid-state lithium-ion secondary battery as described in claim 9, characterized in that, The semi-solid lithium-ion secondary battery satisfies the following formula: ； in, , It can be any one of the following values: 10.0, 11.6, 13.3, 15.5, or 16.

1. It can be any one of 16.8, 17.4, 20.9, or 25.0.

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