High-temperature curing type semi-solid battery, preparation method thereof and electric device

Abstract

The application provides a high-temperature solidification type semi-solid battery, a preparation method thereof and an electric equipment, and relates to the technical field of lithium batteries. The high-temperature solidification type semi-solid battery comprises a positive electrode sheet, a negative electrode sheet, a diaphragm and an electrolyte; the positive electrode sheet comprises a positive electrode active material with active groups grafted on the surface; the electrolyte comprises a carbonate solvent and a lithium salt; the surface of the positive electrode active material is at least partially coated with a three-dimensional polymer network; and the electrolyte does not contain polymer monomers and gelling agents. In the application, the positive electrode active groups are chemically bonded with solvent molecules in situ, so that a three-dimensional network for locking liquid solvent can be constructed on the surface of the positive electrode without adding gelling agents. This design avoids the ion conductivity attenuation and high interface impedance caused by additional additives, and limits the migration of free liquid by using a stable bonding network, so that the problems of electrolyte leakage and cycle aging are solved from the root, and the high safety, high conductivity and long service life are achieved.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and more specifically, to a high-temperature curing semi-solid battery, its preparation method, and electrical equipment. Background Technology

[0002] With the development of energy storage technology, applications such as power batteries are placing more stringent demands on battery energy density, cycle life, and safety performance. Traditional liquid lithium-ion batteries, due to the high fluidity of their internal electrolytes, are prone to safety accidents such as leakage and thermal runaway under extreme conditions such as compression, puncture, or high temperatures. Semi-solid batteries, as a transitional technology, improve battery safety performance by reducing electrolyte fluidity while retaining the advantages of high ionic conductivity of liquid electrolytes, and are gradually becoming a research hotspot in the battery field.

[0003] Currently, the main technical approaches to achieving semi-solid-state batteries in the industry include: first, adding solid electrolyte powder to the system in combination with liquid electrolyte to reduce fluidity through the physical barrier effect of solid electrolyte; second, introducing additional gelling agents (such as polymer monomers and crosslinking agents, etc., polymerization precursors) into the electrolyte to form a gel electrolyte network through polymerization reaction to imprison the liquid electrolyte; and third, modifying the surface of electrode materials to improve the compatibility or contact tightness of the electrode-electrolyte interface.

[0004] However, the existing technical approaches still face numerous technical bottlenecks. First, the solid-state electrolyte composite approach suffers from severe interfacial impedance due to poor solid-liquid phase contact, and uneven powder dispersion easily leads to a degradation in battery rate performance. Second, the gel electrolyte approach, which relies on the addition of gelling agents or polymer monomers, inevitably reduces the ionic conductivity of the system due to the introduction of polymeric additives, and poses a risk of electrolyte contamination by polymerization residues. Furthermore, conventional free gel networks are prone to aging or rupture during long-term charge-discharge cycles, leading to electrolyte re-leakage and unstable solidification. In addition, conventional electrode surface modification techniques mainly focus on improving interfacial charge transfer efficiency, failing to achieve direct fixation of the electrolyte solvent. Therefore, the battery still faces the risk of free liquid migration and leakage after high-temperature cycling or long-term storage.

[0005] In summary, existing semi-solid-state battery technologies generally suffer from technical defects such as unstable solidification effect, easy electrolyte migration and leakage, and high interfacial impedance. Without the introduction of additional polymer precursors, existing systems cannot effectively fix the liquid solvent, thus making it difficult to simultaneously meet the comprehensive requirements of high safety, high ionic conductivity, and long cycle stability.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a high-temperature curing semi-solid battery, a method for preparing a high-temperature curing semi-solid battery, a surface-modified positive electrode active material, a method for preparing a surface-modified positive electrode active material, and an electrical device. The high-temperature curing semi-solid battery forms a three-dimensional polymer network by in-situ chemical bonding between positive electrode active groups and conventional solvent molecules. Without the need for external gelling agents, the liquid solvent is stably anchored on the positive electrode surface, achieving a synergistic improvement in high ionic conductivity, low interfacial impedance, and excellent leak-proof safety performance.

[0008] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: In a first aspect, the present invention provides a high-temperature curing semi-solid battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte; The positive electrode sheet includes a positive electrode active material with active groups grafted onto its surface; The electrolyte comprises a carbonate solvent and a lithium salt; The surface of the positive electrode active material is at least partially coated with a three-dimensional polymer network; wherein the three-dimensional polymer network is formed by in-situ chemical bonding and cross-linking of the active groups and the carbonate solvent, and the carbonate solvent is anchored in the three-dimensional polymer network; The electrolyte does not contain polymer monomers or gelling agents.

[0009] In an optional embodiment, the active group includes at least one selected from amino, epoxy, hydroxy, and carboxyl groups; and / or, The active groups are linked to the surface of the positive electrode active material via carbon chains, wherein the number of straight-chain carbon atoms in the carbon chains is 2 to 6; and / or, The molar density of the active groups on the surface of the positive electrode active material is 1.5 mmol / g to 3.0 mmol / g; and / or, The surface of the positive electrode active material is grafted with organic segments formed by the reaction of a modifier; the organic segments provide the active groups; wherein the modifier includes at least one of the following: linker molecules with two or three-terminal epoxy groups, linker molecules with two or three-terminal unsaturated double bonds, and aminosilane molecules; preferably, the modifier includes at least one of 3-aminopropyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and glycolic acid.

[0010] In an optional embodiment, the lithium salt comprises LiPF6; the LiPF6 in the electrolyte accounts for 10% to 13% by mass; and / or, The three-dimensional polymer network contains at least one of ether bonds, ester bonds, and urethane bonds; and / or, The three-dimensional polymer network forms a positive electrode electrolyte interphase (CEI) film on the surface of the positive electrode active material; the CEI film is configured to inhibit the dissolution of metal ions from the positive electrode active material; and / or... The positive electrode active material includes lithium nickel cobalt manganese oxide; and / or, The negative electrode sheet includes a graphite negative electrode.

[0011] In an optional embodiment, the carbonate solvent includes cyclic carbonates and linear carbonates; Preferably, the cyclic carbonate comprises ethylene carbonate; Preferably, the linear carbonate includes at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; Preferably, the cyclic carbonate accounts for more than or equal to 20% by mass in the electrolyte.

[0012] In an optional embodiment, the electrolyte further includes a solvent containing polymerizable functional groups; Preferably, the solvent containing polymerizable functional groups accounts for 1% to 5% by mass in the electrolyte; Preferably, the solvent containing polymerizable functional groups includes at least one of vinylene carbonate, maleic anhydride, and polyethylene glycol diacrylate.

[0013] In a second aspect, the present invention provides a method for preparing a high-temperature curing semi-solid-state battery, used to prepare a high-temperature curing semi-solid-state battery as described in any of the foregoing embodiments, comprising: A positive electrode, a separator, a negative electrode, and an electrolyte are provided; the positive electrode, the separator, and the negative electrode are assembled and then injected into the electrolyte to obtain a battery to be cured; wherein the lithium salt in the electrolyte includes LiPF6; The battery to be cured is subjected to a programmed temperature curing process; wherein the maximum curing temperature of the programmed temperature curing process is 80℃~120℃; at the maximum curing temperature, LiPF6 in the electrolyte undergoes trace decomposition to produce Lewis acid PF5; the PF5 acts as an in-situ catalyst to activate the active groups or the carbonate solvent, so that the two undergo ring-opening polymerization and chain crosslinking reaction to form the three-dimensional polymer network.

[0014] In an optional implementation, the programmed temperature-curing process sequentially includes: Induction phase: Heat to the first temperature at a rate of 1℃ / min and maintain the temperature for 2 to 4 hours; Main reaction stage: The temperature is increased from the first temperature to the maximum curing temperature at a rate of 0.5℃ / min, and then held at the maximum curing temperature for 6 to 12 hours; Post-curing stage: The temperature is reduced from the highest curing temperature to the second temperature at a rate of 0.2℃ / min, and held at the temperature for 1 hour to 3 hours; Wherein, the first temperature is 75℃~85℃; the maximum curing temperature is 100℃~120℃; and the second temperature is 60℃~75℃.

[0015] Thirdly, the present invention provides a surface-modified positive electrode active material for use in a high-temperature curing semi-solid-state battery as described in any of the foregoing embodiments, wherein the surface of the positive electrode active material is grafted with active groups; the active groups include at least one of amino, epoxy, hydroxyl and carboxyl groups; The active groups are connected to the surface of the positive electrode active material via carbon chains; the number of straight-chain carbon atoms in the carbon chains is 2 to 6. The molar density of the active groups on the surface of the positive electrode active material is 1.5 mmol / g to 3.0 mmol / g.

[0016] Fourthly, the present invention provides a method for preparing a surface-modified positive electrode active material as described in the foregoing embodiments, comprising: Under a protective atmosphere, the positive electrode active material powder is placed in a solution containing an aminosilane modifier and reacted at a constant temperature; after the reaction is completed, it is washed and vacuum dried to obtain the surface-modified positive electrode active material. The concentration of the aminosilane modifier is 1.5 mol / L to 3.0 mol / L; the temperature of the isothermal reaction is 60℃ to 70℃; and the reaction time is 4h to 5h.

[0017] Fifthly, the present invention provides an electrical device comprising a high-temperature curing semi-solid battery as described in any of the foregoing embodiments, or a high-temperature curing semi-solid battery prepared by the preparation method described in the foregoing embodiments.

[0018] Compared with existing technologies, the high-temperature curing semi-solid-state battery provided by this invention achieves in-situ chemical bonding and cross-linking between active groups grafted onto the surface of the positive electrode active material and conventional carbonate solvents in the liquid electrolyte. This forms a three-dimensional polymer network that is at least partially coated on the surface of the positive electrode active material, thereby establishing a direct chemical bond between the solid and liquid. This design completely eliminates the dependence on external polymer monomers, cross-linking agents, or gelling agents, avoiding the loss of ionic conductivity and the risk of pollution from reaction residues caused by the introduction of additional organic additives. This allows the battery system to maintain excellent ionic conductivity and significantly reduce interfacial impedance while achieving a semi-solid-state transformation, effectively solving the pain points of poor two-phase contact and rate performance degradation in traditional semi-solid-state batteries.

[0019] This three-dimensional polymer network firmly and stably anchors solvent molecules from the liquid electrolyte to the positive electrode surface, restricting the migration and flow of free liquid at the microscopic level. Because it forms stable chemical bonds through in-situ reactions, it exhibits superior spatial stability and aging resistance compared to traditional external physical gel networks. Under extreme conditions such as long-term charge-discharge cycles, high-temperature storage, or needle penetration, this network structure is less prone to aging, cracking, or failure. It not only effectively inhibits metal dissolution from the material but also fundamentally eliminates the risk of free electrolyte migration and leakage after high-temperature cycling or long-term storage, thereby achieving simultaneous improvements in battery safety, capacity efficiency, and long-term cycle life. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 The above are comparison spectra of EIS (electrochemical impedance spectroscopy) test results for the batteries of each embodiment (Examples 1-4) and Comparative Example 1 of this application. Figure 2 This is the FT-IR (infrared spectrum) characterization diagram of the positive electrode active material with -NH2 groups grafted on its surface in Example 1 of this application; Figure 3 This is the FT-IR (infrared spectrum) characterization diagram of the positive electrode active material with -OH / -NH2 composite groups grafted on its surface in Example 2 of this application; Figure 4 The images show the internal interface morphology of the batteries in Examples 5 (semi-solid-state battery), 6 (semi-solid-state battery), Comparative Example 2 (conventional gel-type semi-solid-state battery), and Comparative Example 3 (conventional liquid lithium-ion battery) after being fully charged and disassembled. Figure 5 This is a comparison chart of the 0.5C discharge curves of the batteries in various embodiments and comparative examples of this application at a low temperature of -20°C. Figure 6 The diagram shows the state phenomena of the batteries of Example 5 (semi-solid battery), Example 6 (semi-solid battery), Comparative Example 2 (conventional gel semi-solid battery), and Comparative Example 3 (conventional liquid lithium-ion battery) after nail penetration test. Figure 7 The image shows the internal interface morphology of the battery (non-cyclic carbonate) in Comparative Example 4 after it was fully charged and disassembled (A), and the state phenomenon after the nail penetration test (B). Figure 8 The image shows the internal interface morphology of the battery (extremely low grafting concentration) in Comparative Example 5 after it was fully charged and disassembled. Figure 9 The image shows the internal interface morphology of the battery (extremely high grafting concentration) in Comparative Example 6 after it was fully charged and disassembled. Figure 10 The diagram shows the state of the semi-solid-state battery (with added VC) of Embodiment 7 of this application after a nail penetration test. Figure 11 This is a comparison graph of the surface temperature-time change curves of the semi-solid batteries in Embodiments 5 and 7 of this application during the nail penetration test. Figure 12 The images show a comparison of the EIS (electrochemical impedance spectroscopy) spectra of the semi-solid-state batteries from Examples 5 and 7 of this application after they were fully charged and placed at 55°C for 7 days. Detailed Implementation

[0022] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0023] This application provides a high-temperature curing semi-solid battery, including a positive electrode, a negative electrode, a separator, and an electrolyte; the positive electrode includes a positive active material with active groups grafted onto its surface; the electrolyte includes a carbonate solvent and a lithium salt; the surface of the positive active material is at least partially coated with a three-dimensional polymer network; wherein the three-dimensional polymer network is formed by in-situ chemical bonding and cross-linking of the active groups and the carbonate solvent, and the carbonate solvent is anchored in the three-dimensional polymer network; the electrolyte does not contain polymer monomers or gelling agents.

[0024] The semi-solid battery is mainly composed of a positive electrode, a negative electrode, a separator placed between the positive electrode and the negative electrode, and an electrolyte filled inside the system.

[0025] In this embodiment, the positive electrode active material contained in the positive electrode sheet is not a traditional unmodified particle, but rather a micro-particle with grafted active groups pre-attached to its surface. These active groups are firmly anchored to the surface of the microcrystalline framework of the positive electrode active material via covalent bonds.

[0026] The electrolyte exhibits a completely liquid flow state during the initial injection stage. The electrolyte components primarily consist of carbonate solvent and lithium salt. It is important to note that, to ensure the electrolyte maintains excellent bulk ionic conductivity and to avoid contamination of the internal electrochemical environment of the battery by residual organic monomers, the electrolyte system does not contain any additional, independent polymer monomers or conventional gelling agents (such as acrylate monomers, conventional polymer precursors, or free radical initiators that are necessary in conventional gel semi-solid batteries).

[0027] After the high-temperature curing semi-solid battery provided in this application embodiment is prepared, the microscopic surface of the positive electrode active material is at least partially coated with a three-dimensional polymer network. The three-dimensional polymer network in this application embodiment is not formed by external physical addition or bulk solution polymerization, but is constructed through a unique "solid-liquid interface in-situ chemical bonding reaction".

[0028] Specifically, after assembly, the battery undergoes a specific programmed high-temperature curing process. During this process, due to the increased temperature, the electrolyte filling the micropores of the positive electrode sheet comes into close microscopic contact with the active groups on the surface of the positive electrode active material. Driven by the high-temperature environment, the lithium salt (e.g., lithium hexafluorophosphate) in the electrolyte undergoes slight decomposition at the solid-liquid interface, generating trace amounts of Lewis acid intermediates (e.g., phosphorus pentafluoride) in situ. These Lewis acid intermediates act as in-situ activation catalysts, preferentially electrophilically activating adjacent carbonate solvent molecules (especially cyclic carbonate solvent molecules) or active groups on their surface, thereby significantly reducing the activation energy for ring-opening or transesterification reactions of carbonate molecules.

[0029] Subsequently, the active groups grafted onto the surface of the positive electrode active material particles act as strong nucleophilic centers, directly attacking these activated carbonate solvent molecules and initiating in-situ ring-opening polymerization and chain cross-linking chemical reactions at the solid-liquid interface. Through this covalent bonding between the solid surface groups and the liquid solvent molecules, the originally free-flowing carbonate solvent molecules are directly introduced as reactive monomers and transformed into the microscopic lattice units of the polymer network.

[0030] In this embodiment, the surface of the positive electrode active material is "at least partially coated" with a three-dimensional polymer network. This means that the three-dimensional polymer network covers the surface of the positive electrode active material particles in a spatial manner to a degree that, at the microscopic level, completely eliminates the macroscopic fluidity of free solvent molecules at the interface. However, it allows for the existence of microscopic gaps that are not completely locked by the polymer backbone in certain local areas. This incomplete, absolutely sealed coating achieves both the in-situ stable fixation of conventional electrolyte solvent molecules on the positive electrode surface through chemical bonding, preventing liquid migration and leakage, and successfully avoids the obstruction of lithium-ion conduction by the fully sealed coating layer, thus preserving the necessary low-impedance channels for rapid charge transfer of lithium ions at the solid-liquid interface.

[0031] Since the carbonate solvent molecules are ultimately firmly anchored in the three-dimensional polymer network framework in the form of covalent bonds, this semi-solid battery system exhibits excellent high-temperature leak-proof safety performance and excellent needle penetration safety characteristics, while greatly reducing the microscopic interface impedance between the electrode and the electrolyte, thus synergistically maintaining the battery's extremely high capacity efficiency, rate performance and long cycle life.

[0032] In summary, the semi-solid-state battery provided in this embodiment achieves in-situ chemical bonding between the surface active groups of the positive electrode and the conventional carbonate solvent. Without adding external polymer monomers or gelling agents, a three-dimensional polymer network anchored to the liquid solvent is directly constructed on the surface of the positive electrode material. This not only eliminates the loss of ionic conductivity and the increase in interfacial impedance caused by the introduction of additional organic additives at the microscopic level, but also effectively suppresses the ionization and migration leakage of the electrolyte under high temperature, storage, or extreme operating conditions by utilizing stable chemical bonds. While giving the battery excellent high-temperature leakage prevention safety performance and aging resistance, it significantly improves capacity efficiency, rate performance, and long-term cycle stability.

[0033] In some implementations, in order to precisely control the in-situ reaction rate at the solid-liquid interface of the semi-solid battery and synergistically optimize the interfacial impedance and leakage prevention safety of the battery, the modified layer structure on the surface of the positive electrode active material has specific micro-coordination characteristics.

[0034] In some embodiments, the active group includes at least one of amino, epoxy, hydroxy, and carboxyl groups.

[0035] In some embodiments, the active group is attached to the surface of the positive electrode active material via a carbon chain, wherein the number of straight-chain carbon atoms in the carbon chain is 2 to 6.

[0036] These active groups are not directly and rigidly anchored to transition metal atoms on the surface of the cathode active material, but are spatially isolated by an organic carbon chain of a specific length. The number of straight carbon atoms in the carbon chain is limited to 2 to 6. For example, it can be 2, 3, 4, 5, 6, etc. By controlling the number of straight carbon atoms within the above-mentioned specific range, the carbon chain can provide sufficient spatial flexibility and freedom of movement for the active groups at the top, effectively overcoming the steric hindrance of the inorganic crystal surface, thereby rapidly capturing and bonding carbonate solvent molecules filling the pores during the subsequent high-temperature curing stage. At the same time, the carbon chain of this length range can avoid the formation of a dense, stacked insulating layer on the cathode surface, ensuring that the channels for lithium ions at the cathode material interface remain unobstructed.

[0037] In some embodiments, the molar density of the active groups on the surface of the positive electrode active material is 1.5 mmol / g to 3.0 mmol / g.

[0038] To ensure complete solidification of the conventional electrolyte solvent while avoiding electronic insulation defects caused by excessive introduction of organic modifiers, the grafting abundance of the active groups on the surface of the positive electrode active material must be strictly limited. Specifically, the molar density of the active groups on the surface of the positive electrode active material is limited to 1.5 mmol / g to 3.0 mmol / g. For example, it can be 1.5 mmol / g, 1.6 mmol / g, 1.8 mmol / g, 2.0 mmol / g, 2.2 mmol / g, 2.5 mmol / g, 2.8 mmol / g, 3.0 mmol / g, etc. If the molar density is lower than 1.5 mmol / g, the reaction sites are too sparse, and the three-dimensional polymer network structure formed by in-situ chemical bonding is too sparse to effectively lock in all liquid solvent molecules; if the molar density exceeds 3.0 mmol / g, the excessive organic long chains will increase the microscopic charge transfer resistance on the surface of the positive electrode active material particles, resulting in a deterioration in the battery's capacity efficiency and rate performance.

[0039] In some embodiments, the surface of the positive electrode active material is grafted with organic segments formed by the reaction of a modifier; the organic segments provide the active groups; wherein the modifier includes at least one of the following: linker molecules with two or three terminal epoxy groups, linker molecules with two or three terminal unsaturated double bonds, and aminosilane molecules.

[0040] Preferably, the modifier includes at least one of 3-aminopropyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and glycolic acid.

[0041] The surface of the positive electrode active material is grafted with organic segments left after a chemical reaction, such as dehydration condensation, between a specific modifier and the hydroxyl groups on the microscopic surface of the positive electrode active material. The ends or side chains of these organic segments provide the active groups required for the aforementioned in-situ reaction. The modifier includes at least one of the following: linker molecules with two or three terminal epoxy groups, linker molecules with two or three terminal unsaturated double bonds, and aminosilane molecules.

[0042] As a further preferred embodiment, to make the grafting reaction more directional and the reaction products more stable, the modifier can be specifically selected as at least one of 3-aminopropyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and glycolic acid. These specific modifier molecules, when mixed and reacted with the positive electrode active material powder under a protective atmosphere (such as nitrogen or argon), can form a uniformly distributed organic functionalized modification layer with a thickness on the nanometer scale on its microscopic surface. This modification layer exhibits excellent chemical inertness at room temperature, coexisting peacefully with various components in conventional liquid electrolytes, ensuring good process stability of the battery during assembly and electrolyte injection. In the subsequent temperature-programmed curing process, once the temperature reaches the trigger range, the modification layer immediately transforms into a highly active crosslinking initiation center, undergoing directional chemical bonding with conventional carbonate solvent molecules.

[0043] In some preferred embodiments, in order to ensure that the in-situ cross-linking reaction of the solid-liquid interface inside the semi-solid battery can proceed efficiently and spontaneously, while taking into account the system's excellent ion conductivity, this application has specifically configured the conductive salt composition and concentration in the electrolyte.

[0044] In some embodiments, the lithium salt includes LiPF6; the mass percentage of LiPF6 in the electrolyte is 10% to 13%. For example, it can be 10%, 10.2%, 10.5%, 11%, 11.5%, 12%, 12.3%, 12.5%, 12.8%, 13%, etc.

[0045] Limiting the mass percentage within the aforementioned range has extremely important synergistic significance for electrochemical and reaction kinetics: under specific high-temperature curing conditions, lithium hexafluorophosphate in the system undergoes trace decomposition, generating phosphorus pentafluoride (PF5) in situ, which possesses strong Lewis acidity. This phosphorus pentafluoride can act as an in-situ catalyst, efficiently activating the cyclic structure of carbonate solvent molecules or the active groups on the cathode surface, promoting ring-opening polymerization. The aforementioned mass percentage not only provides the optimal concentration of in-situ catalyst to drive the crosslinking reaction but also ensures that the concentration of remaining conductive ions in the system remains within the optimal conductivity range after consuming trace amounts of lithium salt.

[0046] In some embodiments, the three-dimensional polymer network includes at least one of ether bonds, ester bonds, and urethane bonds.

[0047] The presence of these high-bond-energy chemical bonds proves that a true chemical copolymerization has occurred between the active groups on the cathode surface and the solvent molecules in the electrolyte, rather than a simple physical adsorption. This covalent cross-linking architecture endows the interfacial network with extremely high mechanical toughness and thermal stability.

[0048] In some embodiments, the three-dimensional polymer network forms a positive electrolyte interphase (CEI) film on the surface of the positive electrode active material; the CEI film is configured to inhibit the dissolution of metal ions from the positive electrode active material.

[0049] During charge-discharge cycles, especially under high temperature and high pressure conditions, the CEI film can effectively block the physical erosion of the positive electrode particle surface by trace amounts of acidic substances, and stabilize the crystal lattice surface through the coordination of molecular chains, thereby preventing the dissolution and migration of transition metal ions inside the positive electrode from the root, and thus greatly improving the high temperature cycle stability and capacity retention of the battery.

[0050] In some embodiments, the positive electrode active material includes lithium nickel cobalt manganese oxide.

[0051] In some embodiments, the negative electrode sheet comprises a graphite negative electrode.

[0052] To maximize the high energy density and safety advantages of the in-situ semi-solidification technology of this application, the positive electrode active material preferably includes a ternary material of lithium nickel cobalt manganese oxide. Through surface modification and in-situ curing, the inherent interfacial thermal stability defects of lithium nickel cobalt manganese oxide materials can be effectively overcome; at the same time, in conjunction with the negative electrode sheet in the system, which includes a graphite negative electrode, a semi-solid energy storage system with high energy density, long cycle life and extremely high intrinsic safety is constructed.

[0053] In some preferred embodiments, in order to ensure that the active groups on the surface of the positive electrode active material can find sufficient and highly reactive targeted crosslinking molecules, this application has precisely defined the molecular structure and ratio of the carbonate solvent in the electrolyte.

[0054] Specifically, in this embodiment, the carbonate solvent includes cyclic carbonates and linear carbonates.

[0055] Preferably, the cyclic carbonate comprises ethylene carbonate; Preferably, the linear carbonate includes at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; Preferably, the cyclic carbonate accounts for more than or equal to 20% by mass in the electrolyte.

[0056] Because different molecular topologies exhibit significant differences in reaction kinetics under high-temperature catalytic conditions, these two solvents perform different functions in the system of this application.

[0057] On the one hand, the cyclic carbonate preferably includes ethylene carbonate (EC). Ethylene carbonate has a high dielectric constant, enabling efficient dissociation of lithium salts; more importantly, due to the inherent ring strain of its five-membered ring structure, ethylene carbonate molecules are readily activated by trace amounts of Lewis acids during specific high-temperature curing stages, thereby undergoing efficient ring-opening polymerization with the active groups on the cathode surface. Therefore, ethylene carbonate molecules actually constitute the core framework unit for in-situ chemical bonding to form a three-dimensional polymer network.

[0058] On the other hand, the linear carbonate preferably includes at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). The linear structure gives these solvents extremely low viscosity, and they are mainly free or anchored in the pores of the generated three-dimensional polymer network, providing a low-resistance liquid-phase conduction medium for the rapid migration of lithium ions, thereby ensuring excellent rate performance of the battery.

[0059] To balance the crosslinking density of the polymer network with the overall ionic conductivity of the system, the mass percentage of the cyclic carbonate in the electrolyte is limited to 20% or more. For example, this mass percentage can be 20%, 25%, 30%, 40%, 50%, 60%, 70%, or 80%. If the mass percentage of the cyclic carbonate is less than 20% (e.g., using only linear carbonate), the system will lack sufficient ring-opening molecules, resulting in extremely limited in-situ crosslinking reactions on the cathode surface due to insufficient reactant concentration. The generated three-dimensional network will be too sparse to effectively imprison and anchor the liquid solvent, and the battery will still not achieve stable semi-solidification at high temperatures. Ensuring that this percentage is 20% or higher provides sufficient reactive building blocks, ensuring the growth of a sufficiently dense and robust three-dimensional polymer network on the cathode surface. This allows for successful locking of the liquid components within the system without the addition of any gelling agent, achieving an excellent synergy between high ionic conductivity and high leak-proof safety.

[0060] In some preferred embodiments, in order to further enhance the mechanical strength and anchoring stability of the three-dimensional polymer network generated by the in-situ reaction at the solid-liquid interface, the electrolyte further includes a solvent containing polymerizable functional groups.

[0061] Specifically, in this embodiment, the electrolyte further includes a solvent containing polymerizable functional groups.

[0062] The solvent containing polymerizable functional groups has highly reactive unsaturated double bonds or anhydride structures in its molecular structure. During the room-temperature liquid injection stage, it acts as a uniformly dispersed liquid solvent molecule in the system. In the subsequent high-temperature curing stage, these unsaturated structures are activated by thermodynamics and in-situ generated Lewis acid catalysts, enabling them to undergo efficient copolymerization reactions with the active groups on the surface of the positive electrode material and the activated carbonate solvent. Through this copolymerization reaction, the solvent containing polymerizable functional groups effectively acts as a molecular-level "micro-crosslinking aid," significantly enhancing the crosslinking density of the three-dimensional polymer network and the strength and toughness of the three-dimensional spatial framework, thereby endowing the battery with superior resistance to mechanical damage (such as excellent nail penetration test pass rate).

[0063] Preferably, the solvent containing polymerizable functional groups accounts for 1% to 5% by mass in the electrolyte; To achieve the aforementioned enhancement effect without sacrificing the ionic conductivity of the electrolyte phase, the mass percentage of the solvent containing polymerizable functional groups in the electrolyte is strictly controlled to be 1% to 5%. For example, it can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc. Limiting the mass percentage to this minute range provides sufficient cross-linking active sites to strengthen the three-dimensional polymer network at the cathode interface. Furthermore, it avoids a significant increase in the viscosity of the bulk electrolyte or excessive bulk gelation due to excessive polymerizable components, thereby ensuring high-speed transport of free lithium ions in the unreacted solvent channels and guaranteeing excellent capacity efficiency and rate performance of the battery.

[0064] Preferably, the solvent containing polymerizable functional groups includes at least one of vinylene carbonate, maleic anhydride, and polyethylene glycol diacrylate.

[0065] Among them, vinylene carbonate contains highly reactive carbon-carbon double bonds, which can not only help build a stable SEI film on the negative electrode surface, but also rapidly and violently crosslink with the positive electrode surface groups at high temperatures; maleic anhydride has a highly reactive anhydride structure, which helps to form a high-strength polar ester bond network; polyethylene glycol diacrylate utilizes its double-terminated acrylate groups to achieve efficient crosslinking, while its flexible polyether segments can provide additional fast conduction channels for lithium ions, achieving a perfect synergy between mechanical strength and ionic conductivity.

[0066] This application also provides a method for preparing a high-temperature curing semi-solid-state battery, used to prepare the high-temperature curing semi-solid-state battery as described in the foregoing embodiments. The core idea of ​​this preparation method is to break down the complex semi-solidification process into two stages: a front-end "conventional liquid-phase physical assembly" and a back-end "thermally driven in-situ chemical reaction," thereby achieving semi-solid-state leak-proof performance while perfectly compatible with existing mature liquid battery industrial production lines. This includes: Step S1: Provide a positive electrode, a separator, a negative electrode, and an electrolyte; assemble the positive electrode, the separator, and the negative electrode, and inject the electrolyte to obtain a battery to be cured; wherein the lithium salt in the electrolyte includes LiPF6.

[0067] In this step, because the injected electrolyte does not contain any polymer monomers or gelling agents that would cause a dramatic increase in viscosity, its flowability and wetting characteristics are completely consistent with conventional liquid electrolytes. This pure liquid injection method ensures that the electrolyte can fully and uniformly penetrate into the deep microporous network of the positive and negative electrode plates and the separator in a very short time, effectively avoiding the risk of "dead zones" or lithium plating caused by poor wetting, and greatly improving production efficiency and the initial consistency of the battery cell.

[0068] Step S2: The battery to be cured is subjected to a programmed temperature curing process; wherein the maximum curing temperature of the programmed temperature curing process is 80℃~120℃; at the maximum curing temperature, LiPF6 in the electrolyte is decomposed in trace amounts to produce Lewis acid PF5; the PF5 acts as an in-situ catalyst to activate the active groups or the carbonate solvent, so that the two undergo ring-opening polymerization and chain crosslinking reaction to form the three-dimensional polymer network.

[0069] After ensuring sufficient electrolyte saturation, the preparation method enters the core curing stage, which involves performing a programmed temperature curing process on the battery to be cured. In this application, "programmed temperature curing process" refers to inputting controlled thermal energy into the battery system by setting a specific temperature gradient and heating rate to trigger and dominate the direction of chemical reactions at the battery's internal micro-interfaces.

[0070] In this step, the maximum curing temperature of the programmed temperature-curing process is set to 80℃~120℃. For example, it can be 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 118℃, 120℃, etc. The setting of this maximum curing temperature range has extremely strict physicochemical boundary significance. Under the continuous action of the above-mentioned maximum curing temperature, the thermodynamic equilibrium within the system shifts, and a specific lithium salt in the electrolyte, namely lithium hexafluorophosphate (LiPF6), undergoes a controlled, trace-level thermal decomposition reaction.

[0071] Upon trace decomposition of lithium hexafluorophosphate, gaseous Lewis acid phosphorus pentafluoride (PF5) is directly generated in situ within the battery microsystem. Due to the severe electron-deficient state of phosphorus atoms, PF5 molecules exhibit extremely strong Lewis acidity. In the micro-reaction system of this application, the trace amounts of PF5 generated perfectly act as an in-situ catalyst. It can rapidly find electron-rich centers with lone pairs of electrons in the system (such as carbonyl oxygen atoms in carbonate solvent molecules, or oxygen atoms on some active groups on the cathode surface), and form unstable high-energy oxonium ion intermediates through coordination. This in-situ catalytic activation process greatly weakens specific chemical bonds (such as carbon-oxygen bonds) within the target molecule, causing the carbonate solvent or active groups, which are extremely stable at room temperature, to enter an extremely active "critical reaction" state.

[0072] Subsequently, under the synergistic effect of in-situ catalytic activation by PF5, the active groups (such as amino groups acting as nucleophiles) on the surface of the positive electrode active material undergo efficient ring-opening polymerization and subsequent chain cross-linking reactions with the activated carbonate solvent molecules. Through the connection and entanglement of numerous microscopic molecular chains, a three-dimensional polymer network is spontaneously formed at the solid-liquid interface between the positive electrode and the electrolyte. This preparation method ingeniously utilizes the trace decomposition products inherently present inside the battery as the reaction driving engine, transforming free liquid solvent in situ into part of a polymer network with a strong and resilient framework without introducing any external initiator contamination, thus safely and efficiently completing the semi-solidification of the battery.

[0073] In some embodiments, the programmed temperature curing process described in this application employs a multi-stage, stepped temperature control process. By precisely controlling the heating / cooling rate, characteristic temperature value, and isothermal holding time at each stage, a spatially highly uniform three-dimensional polymer network with excellent mechanical properties is constructed at the microscopic level inside the battery cell.

[0074] In some embodiments, the programmed temperature curing process described in this application employs a multi-stage, stepped temperature control process. By precisely controlling the heating / cooling rate, characteristic temperature value, and isothermal holding time at each stage, a spatially highly uniform three-dimensional polymer network with excellent mechanical properties is constructed at the microscopic level inside the battery cell.

[0075] Specifically, the programmed temperature-curing process includes the following three coordinated and continuous stages: (1) Induction stage: Heat to the first temperature at a rate of 1℃ / min and keep it at a constant temperature for 2 to 4 hours.

[0076] First, the process enters the aforementioned induction stage. In this stage, the battery to be cured is steadily heated to a first temperature at a rate of 1°C / min. This first temperature is limited to a temperature range conducive to the mild initiation of the reaction, specifically 75°C to 85°C. For example, it can be 75°C, 76°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, etc. After reaching the first temperature, the battery is kept at a constant temperature for 2 to 4 hours. For example, it can be 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours, 4 hours, etc. This induction stage utilizes gentle heat conduction over a specific period to ensure that heat can overcome the complex physical barriers of the battery's multiple layers, fully penetrating and uniformly distributing to the innermost core of the battery. This eliminates temperature differences within the battery as a whole, promoting the mild and synchronous initiation of localized in-situ catalytic reactions, effectively avoiding structural inhomogeneities caused by excessive localized reactions.

[0077] (2) Main reaction stage: The temperature is increased from the first temperature to the highest curing temperature at a rate of 0.5℃ / min, and then kept at the highest curing temperature for 6 to 12 hours.

[0078] Subsequently, the process seamlessly transitions to the main reaction stage. In this stage, the battery is slowly and continuously increased from the first temperature to the maximum curing temperature at a low rate of 0.5℃ / min. The maximum curing temperature is limited to 100℃~120℃. For example, it can be 100℃, 102℃, 105℃, 108℃, 110℃, 112℃, 115℃, 116℃, 118℃, 120℃, etc. After reaching the maximum curing temperature, a long period of constant temperature maintenance is maintained, lasting 6 hours to 12 hours. For example, it can be 6 hours, 7 hours, 8 hours, 8.5 hours, 9 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, etc. During this stage, the extremely low heating rate ensures that the microscopic heat released by the in-situ ring-opening polymerization and chain crosslinking chemical reactions can be dissipated in a timely and stable manner, avoiding localized thermal runaway. Under prolonged maintenance at the highest curing temperature, the reactant molecules achieve full chain growth and macroscopic cross-linking driven by sufficient thermal energy and highly efficient catalysis by in-situ Lewis acids. Ultimately, a continuous, dense, and tough three-dimensional polymer network is built on the cathode surface, completely chemically anchoring the conventional carbonate solvent.

[0079] (3) Post-curing stage: cool down from the highest curing temperature to the second temperature at a rate of 0.2℃ / min, and keep it at a constant temperature for 1 to 3 hours.

[0080] Finally, the process enters the post-curing stage. After the reaction is basically complete, the battery is cooled from the highest curing temperature to a second temperature at a very slow rate of 0.2℃ / min. The second temperature is limited to 60℃~75℃. For example, it can be 60℃, 62℃, 64℃, 65℃, 66℃, 68℃, 70℃, 72℃, 74℃, 75℃, etc. Within this temperature range, a constant temperature holding period is implemented for 1 hour to 3 hours. For example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, 3 hours, etc. After that, the battery is removed from the ambient temperature range and allowed to cool naturally to room temperature. Due to the significant difference in macroscopic thermal shrinkage rates between the polymer network and the inorganic cathode framework, this stage, through extremely slow temperature control and cooling and low-stability heat preservation for a specific period, serves as an annealing treatment for the microscopic polymer network. This provides the complex cross-linked molecular chain segments with sufficient space relaxation and rearrangement time, completely eliminating the microscopic shear stress accumulated at the solid-liquid interface from a physical perspective. This significantly improves the peel strength and microscopic network curing degree of the three-dimensional polymer network, enabling the semi-solid battery to exhibit extremely stable, aging-resistant, and intrinsically leak-proof safety qualities.

[0081] This application provides a surface-modified positive electrode active material, which is mainly used as an intermediate product in the construction of the aforementioned high-temperature curing semi-solid-state battery. The substrate of the positive electrode active material can be a conventional ternary transition metal oxide intercalation compound such as lithium nickel cobalt manganese oxide.

[0082] Specifically, the surface of the positive electrode active material is grafted with active groups; the active groups include at least one of amino, epoxy, hydroxyl and carboxyl groups; The active groups are connected to the surface of the positive electrode active material via carbon chains; the number of straight-chain carbon atoms in the carbon chains is 2 to 6. The molar density of the active groups on the surface of the positive electrode active material is 1.5 mmol / g to 3.0 mmol / g.

[0083] In terms of microstructure, the surface of the positive electrode active material particles is firmly grafted with a specific organic modification layer via covalent bonds. The microscopic ends or side chains of the organic modification layer provide active groups that can participate in subsequent in-situ crosslinking reactions. The active groups include at least one of amino, epoxy, hydroxyl, and carboxyl groups. These active groups exhibit good thermodynamic stability in the external environment, enabling the material to be stored and transported for a long time in a dry environment.

[0084] To eliminate the strong microscopic steric hindrance caused by the rigid crystal surface of inorganic active particles to functional groups, the active groups are not directly connected to the transition metal atoms on the inorganic crystal surface, but are connected to the surface of the positive electrode active material through a flexible low-alkyl carbon chain. To ensure sufficient spatial free collision probability of the groups while preventing the organic long chains from self-assembling and accumulating on the particle surface to form an insulating layer, the number of straight carbon atoms in the carbon chain is limited to 2-6. For example, it can be 2, 3, 4, 5, 6, etc. This specific carbon chain span allows the modified layer to be distributed in a nanoscale thin film in space. During subsequent interfacial contact reactions, the groups can efficiently extend outward and capture corresponding liquid-phase targeted reaction molecules; simultaneously, the length of this flexible chain segment does not hinder the microscopic lattice insertion and extraction movement of lithium ions, synergistically ensuring the excellent electrochemical interfacial activity of the material.

[0085] To establish a uniformly distributed and appropriately abundant matrix of reaction sites on the surface of the inorganic substrate material, the grafting abundance of the active groups on the surface of the positive electrode active material is strictly quantitatively controlled. Specifically, the molar density of the active groups on the surface of the positive electrode active material is strictly limited to 1.5 mmol / g to 3.0 mmol / g. For example, it can be 1.5 mmol / g, 1.6 mmol / g Spice, 1.8 mmol / g, 2.0 mmol / g, 2.2 mmol / g, 2.4 mmol / g, 2.6 mmol / g, 2.8 mmol / g, 2.9 mmol / g, 3.0 mmol / g, etc. If the molar density of the active groups is less than 1.5 mmol / g, the reactive sites on the particle surface are too scarce. During subsequent solidification with an external liquid solvent, a three-dimensional framework network with sufficient cross-linking density cannot be constructed, resulting in the inability to completely anchor the flowing liquid molecules. If the molar density of the active groups exceeds 3.0 mmol / g, on the one hand, the excessively thick and dense organic modification layer will forcibly cover all electrochemical active sites on the surface of the cathode active material crystal; on the other hand, these electronically insulating organic segments will significantly increase the microscopic charge transfer impedance and contact resistance between cathode particles, leading to defects such as high internal resistance and reduced capacity efficiency in the final battery. Therefore, controlling the molar density within the aforementioned specific range is the key microstructural basis for ensuring that the intermediate material can achieve both high subsequent solidification efficiency and maintain low impedance and high capacity characteristics.

[0086] In some embodiments, this application provides a method for preparing a surface-modified positive electrode active material. This method employs a wet chemical surface modification process, aiming to stably construct an organic modification layer with highly reactive groups on the microscopic surface of the inorganic positive electrode active powder.

[0087] Specifically, the preparation method includes: Under a protective atmosphere, the positive electrode active material powder is placed in a solution containing an aminosilane modifier and reacted at a constant temperature; after the reaction is completed, it is washed and vacuum dried to obtain the surface-modified positive electrode active material. The concentration of the aminosilane modifier is 1.5 mol / L to 3.0 mol / L; the temperature of the isothermal reaction is 60℃ to 70℃; and the reaction time is 4h to 5h.

[0088] Specifically, the preparation method first involves placing the positive electrode active material powder in a solution containing an aminosilane modifier under a protective atmosphere and conducting a isothermal reaction. The protective atmosphere can be an inert gas environment such as high-purity nitrogen (N2) or argon (Ar). Introducing a protective atmosphere effectively isolates the positive electrode active material powder from moisture and oxygen in the ambient air, preventing irreversible oxidation and deterioration in the liquid phase environment. Simultaneously, it inhibits the hydrolysis and self-polymerization reaction of the aminosilane modifier molecules in the bulk solution, thereby ensuring that the modifier molecules can efficiently diffuse in monomer form to the microscopic surface of the positive electrode particles and undergo directional grafting.

[0089] In order to achieve the optimal surface grafting abundance and synergistic control of the material's microresistivity, the concentration of the reaction solution and the thermodynamic conditions of the reaction were subject to extremely strict quantitative limits in this step.

[0090] First, the concentration of the aminosilane modifier is limited to 1.5 mol / L to 3.0 mol / L. For example, it can be 1.5 mol / L, 1.6 mol / L, 1.8 mol / L, 2.0 mol / L, 2.2 mol / L, 2.4 mol / L, 2.5 mol / L, 2.6 mol / L, 2.8 mol / L, 3.0 mol / L, etc. This reactant concentration range directly determines the reaction kinetic rate at the interface and the molar density of active groups on the final material surface. Maintaining the concentration within this range ensures that there are sufficient silane molecules in the liquid phase system to diffuse and collide with the inorganic solid phase surface, thereby constructing a modified layer with a suitable density. This satisfies the strength requirements of the subsequent crosslinking network and avoids the accumulation of insulating layers due to excessive reagents.

[0091] Secondly, the isothermal reaction temperature is limited to 60℃~70℃. For example, it can be 60℃, 61℃, 62℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, etc. Furthermore, the isothermal reaction time is strictly controlled within 4h~5h. For example, it can be 4h, 4.1h, 4.2h, 4.3h, 4.4h, 4.5h, 4.6h, 4.8h, 4.9h, 5h, etc. This specific "temperature-time" kinetic window provides just the right activation energy for the reaction. Under these conditions, the siloxane end groups of the aminosilane molecules can undergo a sufficient dehydration condensation reaction with the hydroxyl groups on the surface of the positive electrode active particles, forming extremely stable covalent bonds, while simultaneously avoiding material lattice damage or thermal deactivation of the amino groups caused by prolonged high-temperature treatment.

[0092] After the liquid-phase isothermal reaction is completed, the preparation method enters the post-processing stage, namely, washing and vacuum drying of the system to finally obtain the surface-modified positive electrode active material. In the washing step, anhydrous ethanol or other polar organic solvents with good solubility for aminosilanes are typically used to repeatedly centrifuge and wash the reacted powder. This process can thoroughly strip and remove free modifier impurities that are physically adsorbed in the pores of the positive electrode particles and have not undergone covalent bonding, preventing them from initiating side reactions in the subsequent battery electrochemical system. The subsequent vacuum drying step (e.g., processing under 100°C vacuum conditions) can quickly remove the washing residue, and simultaneously utilize the residual heat energy to drive the incompletely reacted silanol bonds at the interface to undergo complete high-temperature condensation and ring closure, completing the final solidification of the organic active modification layer from both physical and chemical dimensions, resulting in a high-purity, stable intermediate product.

[0093] This application also provides an electrical device, including a high-temperature curing semi-solid battery as described in the foregoing embodiments, or a high-temperature curing semi-solid battery prepared by the preparation method described in the foregoing embodiments.

[0094] This electrical device is equipped with the aforementioned high-temperature curing semi-solid-state battery, which serves as a power source or energy storage unit. Thanks to the superior leak-proof safety performance, excellent ion conductivity, and long-term cycle stability provided by the integrated solid-liquid micronetwork within the semi-solid-state battery, this device exhibits higher intrinsic safety and longer-lasting power output from the system's core, even under complex mechanical shocks, extreme temperature environments, or prolonged frequent use. Specifically, this electrical device can encompass any device, system, or mobile equipment that uses a battery as its energy carrier. Specific types include, but are not limited to: new energy vehicles (such as pure electric vehicles, plug-in hybrid electric vehicles, hybrid electric vehicles, electric bicycles, electric motorcycles, etc.), various energy storage systems (such as large-scale grid-scale energy storage power stations, industrial and commercial energy storage equipment, portable home energy storage power supplies, etc.), consumer electronic devices (such as smartphones, tablets, laptops, smart wearable devices, digital cameras, etc.), as well as drones, intelligent robots, power tools, medical devices, and other electrical-related equipment.

[0095] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0096] Experimental Example 1: Investigating the effect of grafted molecule carbon chain length on the electrochemical performance of semi-solid-state batteries 1. Experimental instructions: This group of experiments (including Examples 1-4 and Comparative Example 1) mainly investigated the effects of grafting modifiers with different numbers of straight-chain carbon atoms (C1~C8) onto the surface of the positive electrode active material on the final semi-solid battery capacity utilization efficiency and interfacial impedance (EIS), in order to verify the optimal balance between carbon chain length and "anchoring solvent" and "reserving lithium-ion transport channels".

[0097] 2. Setting of experimental subjects: Please refer to Table 1 for details.

[0098] Table 1. Summary of cathode modification schemes (or grafted molecules) for each embodiment and comparative example.

[0099] Comparative Example 1: This comparative example provides an unmodified conventional battery with an unmodified lithium nickel cobalt manganese oxide (NCM) as its positive electrode active material.

[0100] Example 1: This example provides a semi-solid battery, the modifier of which is a C1 short-chain "aminomethyltriethoxysilane".

[0101] Example 2: This example provides a semi-solid battery, the modifier of which is "3-glycidyl etheroxypropyltrimethoxysilane" with a C3 carbon chain.

[0102] Example 3: This example provides a semi-solid battery, the modifier of which is "6-aminohexyltrimethoxysilane" with a C6 carbon chain.

[0103] Example 4: This example provides a semi-solid battery, the modifier of which is C8 long-chain "8-aminooctyltrimethoxysilane".

[0104] 3. Experimental methods: Modification of positive electrode active material: NCM powder was placed in aminosilane modifier solutions with a concentration of 1.5 mol / L to 3 mol / L corresponding to the above embodiments, and reacted at a constant temperature of 60°C for 4 hours under a nitrogen protective atmosphere. After the reaction, the powder was washed 4 times with anhydrous ethanol to remove unreacted modifier, and then dried under vacuum at 100°C for 8 hours to obtain functionalized NCM powder.

[0105] Positive electrode preparation: Functionalized NCM powder, polyvinylidene fluoride (PVDF) binder, and carbon black conductive agent are mixed in a mass ratio of 90:6:4, NMP solvent is added to prepare a uniform slurry, which is then coated onto an aluminum foil current collector and rolled.

[0106] Battery assembly and curing: The positive electrode, separator, and graphite negative electrode are stacked and assembled in sequence; electrolyte (EC / DMC=1:1, 1.0 mol / L LiPF6 added, injection volume 3 g / Ah) is injected; then the battery is placed in an 80℃ constant temperature oven for curing for 3 h, and sealed to obtain the target battery.

[0107] 4. Experimental Results and Analysis: The battery was subjected to a constant current and constant voltage test from 0.2C to 3.75V to 0.05C, and the EIS impedance of the battery was tested at 50% SOC.

[0108] (1) The results of capacity separation efficiency and internal resistance are shown in Table 2: Table 2. Test results of first-cycle capacity-limiting efficiency and internal resistance of batteries in various embodiments and comparative examples.

[0109] (2) Impedance fitting results: Reference Figure 1 and Table 3: Table 3. EIS interface impedance fitting results for each embodiment and comparative example battery.

[0110] (3) Results Analysis: The data shows that when the carbon chain is too short (e.g., C1), the groups adhere tightly to the positive electrode surface, resulting in large steric hindrance and making it difficult to react fully with the solvent; when the carbon chain is too long (e.g., C8), the long chain structure forms an insulating barrier on the particle surface, severely hindering the transport of lithium ions, leading to a significant increase in interfacial impedance (Rf and Rct) and a decrease in capacity separation efficiency. The optimal choice is a C2~C6 length (especially the C3 carbon chain in Example 2), which has sufficient spatial freedom to capture solvent molecules while preserving a smooth transport channel for lithium ions, achieving an excellent synergy between high conductivity and low impedance.

[0111] Experiment Example 2: Performance Comparison of Different Surface Grafting Groups and Traditional Gel Systems 1. Experimental Description: This group of experiments (for ease of distinction, the examples and comparative examples that were repeatedly named in the original disclosure are described separately here) mainly investigated the differences between high-temperature curing semi-solid batteries with single and composite groups grafted onto the positive electrode surface and semi-solid batteries with added traditional gelling agents in terms of infrared characterization, battery disassembly, low-temperature performance and needle penetration safety performance.

[0112] 2. Methods for setting and preparing experimental subjects: (1) Example 5: Semi-solid battery with NCM surface grafted with -NH2 groups. This example investigated the curing effect of single amino grafting. NCM powder was placed in a 2 mol / L solution of "3-aminopropyltriethoxysilane" and reacted at 60°C for 4 h. After washing, it was vacuum dried at 100°C for 8 h. The electrode, separator, and graphite negative electrode were stacked together, injected with ordinary electrolyte, and cured at 80°C for 3 h.

[0113] Characterization results: FT-IR characterization showed that functionalized NCM exhibited a characteristic absorption peak of -NH2 in the 3380–3450 cm⁻¹ region (reference). Figure 2 This proves that the grafting was successful; According to ICP (Inductively Coupled Plasma Emission Spectroscopy), the mass fraction of -NH2 on the surface of the modified positive electrode active material in Example 5 is about 1%. Combined with molecular weight conversion and thermogravimetric analysis (TGA), the molar density of active groups on its surface is about 1.8 mmol / g, which falls exactly within the preferred protection range of 1.5 mmol / g to 3.0 mmol / g. Further thermogravimetric analysis (TGA) determined that the molar density of -NH2 groups on the surface of the surface-modified positive electrode active material in Example 5 was 1.8 mmol / g, which falls within the preferred range of 1.5 mmol / g to 3.0 mmol / g.

[0114] (2) Example 6: Semi-solid-state battery with -OH / -NH2 composite groups grafted onto NCM surface. This example investigated the synergistic effect of the composite groups. The modifier used was a mixed solution of "3-aminopropyltriethoxysilane" and "hydroxyacetic acid" (molar ratio 1:1, total concentration 2 mol / L). The grafting temperature was 70℃ for 5 h; the high-temperature curing temperature was 90℃ for 2.5 h. Characterization results: Infrared characterization showed that both -NH2 and -OH characteristic signals were present on the surface (reference). Figure 3 ).

[0115] According to ICP measurements, the mass fraction of -NH2 and -OH composite groups on the surface of the modified positive electrode active material in Example 6 is about 0.8%, and the total molar density of active groups on its surface is also in the range of 1.5 mmol / g to 3.0 mmol / g.

[0116] (3) Comparative Example 2: Traditional Gel Semi-Solid Battery This comparative example examines existing technical routes. The positive electrode was prepared using unmodified NCM powder; during electrolyte injection, 5% PETA polymer monomer + 0.2% AIBN gel initiator were added to the electrolyte, and in-situ polymerization was initiated at high temperature to form a traditional gel electrolyte.

[0117] (4) Comparative Example 3: The conventional liquid lithium-ion battery uses ungrafted lithium nickel cobalt manganese oxide (NCM) powder as the positive electrode active material and prepares the positive electrode sheet according to the same process as in Example 5. During battery assembly, the positive electrode sheet, separator, and graphite negative electrode sheet are stacked and assembled into a battery in sequence. Conventional liquid electrolyte (ethylene carbonate EC / dimethyl carbonate DMC=1:1, with 1.0 mol / L LiPF6 added) is injected into the battery at a volume of 3 g / Ah. After the electrolyte injection is completed, the battery is directly sealed without any programmed temperature curing or high-temperature oven heating steps, keeping the internal electrolyte completely in a conventional free liquid state, thus obtaining a conventional liquid lithium-ion battery.

[0118] 3. Battery Safety and Electrochemical Testing and Analysis: The assembled batteries were subjected to the following three tests: (1) Test 1: Full-charge disassembly test. The battery was charged at 0.5C constant current and constant voltage to 4.2V, and cut off at 0.05C. After being fully charged, the battery was disassembled and the solidification of the internal interface was observed (refer to Table 4 and Figure 4 (These correspond to Examples 5, 6, and the comparative experiment of this group, respectively).

[0119] Table 4. Summary of Full-Charge Disassembly Test Results of Batteries in Each Example and Comparative Example

[0120] (2) Test 2: Low temperature discharge performance test After the battery is fully charged at 0.5C, its 0.5C discharge capacity is tested in a low temperature environment of -20℃ (refer to Table 5 and the low temperature discharge curve). Figure 5 The test results show that the embodiments of this application do not require the addition of an external gelling agent, and the ionic conductivity of the electrolyte is not lost. Therefore, compared with the traditional gel route (Comparative Example 2), the semi-solid battery of this application exhibits a better discharge capacity retention rate in low-temperature environments.

[0121] Table 5. Results of low-temperature discharge capacity tests at -20℃ for each embodiment and comparative example battery.

[0122] (3) Test 3: Needle penetration safety test. After the battery is fully charged at 0.5C, a 5mm smooth steel needle (needle tip cone angle 45°) is used to vertically penetrate the center of the battery surface at a speed of 25±5mm / s. The battery is left for 1 hour to observe leakage and thermal runaway (refer to Table 6 and the test site). Figure 6 ).

[0123] Table 6. Summary of Nail Penetration Safety Test Results for Each Example and Comparative Example

[0124] (4) Results analysis: The test results show that in Examples 5 and 6, the groups on the positive electrode surface and the carbonate solvent in the electrolyte were chemically bonded in situ (under the catalysis of trace amounts of LiPF6 high-temperature decomposition product PF5, ring-opening polymerization and chain crosslinking were initiated), forming a three-dimensional polymer network anchored by chemical bonds.

[0125] Compared to the physically confined traditional gel network in the comparative example, the chemically anchored network of the present invention can effectively limit the migration of liquid solvent when subjected to extreme damage such as steel needle puncture, without leakage or severe thermal runaway, exhibiting excellent intrinsic safety characteristics.

[0126] Furthermore, thanks to the three-dimensional polymer network coating generated in situ on the surface of the positive electrode active material, a stable chemical anchoring matrix of transition metal atoms (i.e., the positive electrode electrolyte intermediate phase CEI film) is constructed on the positive electrode surface.

[0127] Experimental tests show that after long charge-discharge cycles and high-temperature storage tests, the concentrations of transition metal (nickel, cobalt, manganese) ions detected in the electrolytes of the batteries in Examples 5 and 6 are significantly lower than those in Comparative Examples 2 and 3. This further confirms that the three-dimensional polymer network constructed in this application can effectively block the physical erosion of harmful acidic byproducts, significantly inhibit the dissolution of metal ions from the positive electrode active material at the micro-lattice level, and synergistically improve the high-temperature cycle life and capacity retention of the battery.

[0128] Experiment Example 3: Critical significance of key parameters and verification of the enhancing effect of functional additives 1. Experimental Description: The purpose of this experiment is to further verify the critical significance of the specific carbonate component ratio and the molar density of surface active groups in the technical solution of this invention, as well as the enhancement effect of introducing solvents containing polymerizable functional groups (such as VC) on the strength of the polymer network.

[0129] 2. Setting and preparation of experimental subjects: Based on the preparation conditions of Example 5, the following examples and comparative examples were added in parallel: Example 7 (Introduction of trace polymerizing additives): The preparation process is exactly the same as in Example 5, except that 2% by mass of vinylene carbonate (VC) is added to the electrolyte as a solvent containing polymerizable functional groups.

[0130] Comparative Example 4 (with cyclic carbonates removed): The preparation process was exactly the same as in Example 5, except that the electrolyte solvent was replaced with a pure linear carbonate combination (DMC:EMC=1:1, i.e., the proportion of cyclic carbonate EC was 0).

[0131] Comparative Example 5 (extremely low grafting concentration): The preparation process is basically the same as that of Example 5, except that the concentration of the modifier and the reaction time are greatly reduced, so that the molar density of the positive electrode surface active groups is only 0.5 mmol / g.

[0132] Comparative Example 6 (extremely high grafting concentration): The preparation process is basically the same as that of Example 5, except that the concentration of the modifier and the reaction temperature are greatly increased, resulting in a molar density of active groups on the positive electrode surface as high as 4.5 mmol / g.

[0133] 3. Test Results and Analysis: (1) Verification of the critical significance of the proportion of cyclic carbonates (Comparative Example 4): The battery of Comparative Example 4 was subjected to a programmed temperature rise curing treatment of 80℃-110℃ using the same process as described above, and then fully charged disassembly and nail penetration test were performed. The results are as follows: Figure 7 As shown in Figures A (fully charged disassembly) and B (after needle penetration test), after disassembly of Comparative Example 4, there were serious traces of free electrolyte on the surface of the electrode, with no solidification or cross-linking phenomenon; and the battery directly caught fire and bulged during the needle penetration test.

[0134] These comparative results strongly support the structural requirement in this application that "the carbonate solvent must contain cyclic carbonates (preferably ≥20%)". Without cyclic carbonates with ring strain, such as EC, the system cannot undergo ring-opening crosslinking reactions under trace amounts of PF5 catalysis, and a three-dimensional polymer network cannot be formed. This results in the battery remaining in a pure liquid state, thus losing the intrinsic safety of a semi-solid-state battery.

[0135] (2) Extreme boundary verification regarding the molar density of active groups (Comparative Example 5, Comparative Example 6): The batteries of Example 5, Comparative Example 5, and Comparative Example 6 underwent first-cycle capacity testing and full-charge disassembly tests. The test data and interface conditions are compared in Table 7. Figure 4 , Figure 8 , Figure 9 .

[0136] Table 7. Comparison of the Influence of the Molar Density Limit of Active Groups on Battery Performance

[0137] Data shows that controlling the molar density of active groups within the range of 1.5–3.0 mmol / g has extremely stringent critical requirements. As shown in Comparative Example 5, when the grafting density is too low (<1.5 mmol / g), there are insufficient reaction sites, making it impossible to effectively lock in the liquid solvent.

[0138] As shown in Comparative Example 6, when the grafting density is too high (>3.0 mmol / g), on the one hand, the in-situ cross-linking reaction will become too violent and out of control (the residual heat inside the battery after baking can directly block and solidify the injection port), resulting in extremely poor microscopic contact at the interface; on the other hand, the excessively thick organic modification layer will cause the positive electrode particles to become insulated, causing the battery internal resistance to rise abnormally to 1.22 mΩ, and the capacity grading efficiency will decrease significantly.

[0139] (3) Verification of the enhancing effect of solvents containing polymerizable functional groups (Example 7): The batteries from Examples 7 and 5 were subjected to nail penetration and high-temperature storage tests, respectively. In the nail penetration test (refer to...), Figure 10 Example 7 demonstrates excellent intrinsic safety characteristics (no fire, no leakage).

[0140] Furthermore, Figure 11 The diagram shows a comparison of the battery surface temperature changes over time during the nail penetration test in Examples 5 and 7. Figure 11 As shown, in Example 5 (orange curve), which did not contain a solvent with polymerizable functional groups, the surface temperature of the battery rose rapidly after needle puncture, reaching a maximum temperature in the range of 80°C to 140°C, and the heat generation was inconsistent. In contrast, in Example 7 (black curve), which contained trace amounts of VC, the heat generation after needle puncture was extremely low, the maximum surface temperature of the battery was effectively suppressed and stabilized at around 50°C to 60°C, and the consistency of multiple parallel tests was excellent.

[0141] The significant difference in temperature-time curves further and intuitively verifies the transformative enhancement effect of introducing 1%–5% of solvents containing polymerizable functional groups (such as VC) into the electrolyte. VC molecules contain highly reactive carbon-carbon double bonds, which, during the temperature-programmed curing stage, can act as highly active crosslinking nodes, efficiently copolymerizing with groups on the positive electrode surface and other solvent molecules. This micro-copolymerization reaction significantly improves the crosslinking density and skeletal strength of the three-dimensional polymer network. When subjected to extreme mechanical and thermal shocks such as needle puncture, the stronger polymer network in Example 7 can more firmly anchor liquid solvent molecules, preventing the violent exothermic reaction and solvent vaporization caused by internal short circuits, thereby fundamentally cutting off the chain reaction of thermal runaway and endowing the semi-solid-state battery with extremely excellent resistance to thermal runaway. Furthermore, after fully charging the batteries of Examples 5 and 7 at constant current and constant voltage at room temperature, they were placed in a high-temperature environment of 55°C for 7 days, and then their EIS electrochemical impedance was tested at room temperature. The comparison results are as follows: Figure 12 As shown (blue curve represents Example 7, black curve represents Example 5).

[0142] Depend on Figure 12 The impedance spectroscopy clearly shows that after harsh high-temperature curing, the high-frequency semicircle of Example 7 (representing interfacial impedance Rf and charge transfer impedance Rct) is significantly smaller than that of Example 5. This fully demonstrates that introducing 1%–5% of a solvent containing polymerizable functional groups (such as VC) into the electrolyte allows its double bond structure to participate in crosslinking during in-situ curing, acting as microscopic crosslinking nodes. This synergistic copolymerization significantly enhances the mechanical strength and chemical resistance of the three-dimensional polymer network on the cathode surface, more effectively protecting the cathode interface under harsh high-temperature environments and suppressing side reactions and impedance deterioration.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature curing semi-solid-state battery, characterized in that, Includes positive electrode, negative electrode, separator, and electrolyte; The positive electrode sheet includes a positive electrode active material with active groups grafted onto its surface; The electrolyte comprises a carbonate solvent and a lithium salt; The surface of the positive electrode active material is at least partially coated with a three-dimensional polymer network; wherein the three-dimensional polymer network is formed by in-situ chemical bonding and cross-linking of the active groups and the carbonate solvent, and the carbonate solvent is anchored in the three-dimensional polymer network; The electrolyte does not contain polymer monomers or gelling agents.

2. The high-temperature curing semi-solid battery as described in claim 1, characterized in that, The active group includes at least one selected from amino, epoxy, hydroxy, and carboxyl groups; and / or, The active groups are linked to the surface of the positive electrode active material via carbon chains, wherein the number of straight-chain carbon atoms in the carbon chains is 2 to 6; and / or, The molar density of the active groups on the surface of the positive electrode active material is 1.5 mmol / g to 3.0 mmol / g; and / or, The surface of the positive electrode active material is grafted with organic segments formed by the reaction of a modifier; the organic segments provide the active groups; wherein the modifier includes at least one of the following: linker molecules with two or three ends of epoxy groups, linker molecules with two or three ends of unsaturated double bonds, and aminosilane molecules; preferably, the modifier includes at least one of 3-aminopropyltriethoxysilane, 3-glycidyl etheroxypropyltrimethoxysilane, and glycolic acid.

3. The high-temperature curing semi-solid-state battery as described in claim 1, characterized in that, The lithium salt includes LiPF6; the LiPF6 in the electrolyte comprises 10% to 13% by mass; and / or, The three-dimensional polymer network contains at least one of ether bonds, ester bonds, and urethane bonds; and / or, The three-dimensional polymer network forms a positive electrode electrolyte interphase (CEI) film on the surface of the positive electrode active material; the CEI film is configured to inhibit the dissolution of metal ions from the positive electrode active material; and / or... The positive electrode active material includes lithium nickel cobalt manganese oxide; and / or, The negative electrode sheet includes a graphite negative electrode.

4. The high-temperature curing semi-solid-state battery as described in claim 1, characterized in that, The carbonate solvent includes cyclic carbonates and linear carbonates; Preferably, the cyclic carbonate comprises ethylene carbonate; Preferably, the linear carbonate includes at least one of dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; Preferably, the cyclic carbonate accounts for more than or equal to 20% by mass in the electrolyte.

5. The high-temperature curing semi-solid-state battery as described in claim 1, characterized in that, The electrolyte also includes a solvent containing polymerizable functional groups; Preferably, the solvent containing polymerizable functional groups accounts for 1% to 5% by mass in the electrolyte; Preferably, the solvent containing polymerizable functional groups includes at least one of vinylene carbonate, maleic anhydride, and polyethylene glycol diacrylate.

6. A method for preparing a high-temperature curing semi-solid-state battery, used to prepare the high-temperature curing semi-solid-state battery as described in any one of claims 1-5, characterized in that, include: A positive electrode, a separator, a negative electrode, and an electrolyte are provided; the positive electrode, the separator, and the negative electrode are assembled and then injected into the electrolyte to obtain a battery to be cured; wherein the lithium salt in the electrolyte includes LiPF6; The battery to be cured is subjected to a programmed temperature curing process; wherein the maximum curing temperature of the programmed temperature curing process is 80℃~120℃; at the maximum curing temperature, LiPF6 in the electrolyte undergoes trace decomposition to produce Lewis acid PF5; the PF5 acts as an in-situ catalyst to activate the active groups or the carbonate solvent, so that the two undergo ring-opening polymerization and chain crosslinking reaction to form the three-dimensional polymer network.

7. The method for preparing a high-temperature curing semi-solid-state battery as described in claim 6, characterized in that, The programmed temperature-curing process includes the following steps: Induction phase: Heat to the first temperature at a rate of 1℃ / min and maintain the temperature for 2 to 4 hours; Main reaction stage: The temperature is increased from the first temperature to the maximum curing temperature at a rate of 0.5℃ / min, and then held at the maximum curing temperature for 6 to 12 hours; Post-curing stage: The temperature is reduced from the highest curing temperature to the second temperature at a rate of 0.2℃ / min, and held at the temperature for 1 hour to 3 hours; Wherein, the first temperature is 75℃~85℃; the maximum curing temperature is 100℃~120℃; and the second temperature is 60℃~75℃.

8. A surface-modified positive electrode active material, used in the high-temperature curing semi-solid-state battery as described in any one of claims 1-5, characterized in that, The surface of the positive electrode active material is grafted with active groups; the active groups include at least one of amino, epoxy, hydroxyl and carboxyl groups; The active groups are connected to the surface of the positive electrode active material via carbon chains; the number of straight-chain carbon atoms in the carbon chains is 2 to 6. The molar density of the active groups on the surface of the positive electrode active material is 1.5 mmol / g to 3.0 mmol / g.

9. A method for preparing a surface-modified positive electrode active material as described in claim 8, characterized in that, include: Under a protective atmosphere, the positive electrode active material powder is placed in a solution containing an aminosilane modifier and reacted at a constant temperature. After the reaction is complete, the material is washed and vacuum dried to obtain the surface-modified positive electrode active material. The concentration of the aminosilane modifier is 1.5 mol / L to 3.0 mol / L; the temperature of the isothermal reaction is 60℃ to 70℃; and the reaction time is 4h to 5h.

10. An electrical appliance, characterized in that, This includes the high-temperature curing semi-solid-state battery as described in any one of claims 1-5, or the high-temperature curing semi-solid-state battery prepared by the preparation method described in claim 6 or 7.

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