Secondary battery, method for manufacturing the same, battery device, power consumption device, and energy storage device

Abstract

The embodiment of the present application relates to the field of batteries, and provides a secondary battery and a preparation method thereof, a battery device, a power utilization device and an energy storage device, the preparation method of the secondary battery comprising: providing an electrode core assembly, the electrode core assembly being formed by laminating or winding a positive electrode sheet, a separator and a negative electrode sheet; providing a shell, the shell having an accommodating cavity, and placing the electrode core assembly in the accommodating cavity; providing an initial electrolyte, and injecting the initial electrolyte into the accommodating cavity; and performing a formation step; the surface of the positive electrode sheet and the surface of the negative electrode sheet are both attached with a gel polymer electrolyte film, the gel polymer electrolyte film contains a triple dynamic network structure, and the triple dynamic network structure comprises a polyurethane main chain hydrogen bond network, a uracil ketone supramolecular hydrogen bond network and a disulfide dynamic covalent bond network. The embodiment of the present application at least endows the electrode material with a hierarchical self-repairing capability, and also enables the electrode material to intelligently respond to changes in the working environment of the battery.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to a secondary battery and its preparation method, battery device, power consumption device and energy storage device. Background Technology

[0002] Lithium-sulfur batteries, with their extremely high theoretical specific capacity (1675 mAh / g) and theoretical specific energy density (2600Wh / kg), which are 5 to 8 times higher than existing lithium-ion batteries, also have significant advantages such as abundant sulfur resources, low cost, and environmental friendliness. They are recognized as one of the most promising post-lithium-ion battery technologies for industrialization.

[0003] However, lithium-sulfur batteries still face severe technical challenges in their transition from laboratory to industrialization. The most critical bottleneck is the "polysulfide shuttle" effect: the sulfur cathode undergoes complex multi-step electrochemical reactions during charging and discharging, generating a series of soluble lithium polysulfide intermediates (Li2S). x (x=4~8). These intermediate products are highly soluble in commonly used ether electrolytes and will freely diffuse between the positive and negative electrodes under the drive of concentration gradient and electric field, causing serious problems such as continuous loss of active sulfur material, rapid capacity decay of battery, low coulombic efficiency, and lithium anode corrosion.

[0004] Meanwhile, the interfacial stability between the electrode and electrolyte in lithium-sulfur batteries is equally critical. Uneven deposition / stripping and volume changes of the lithium metal anode during charge and discharge, as well as the density and morphological evolution of the sulfur cathode during polysulfide conversion, can easily lead to deterioration of the physical contact between the electrode and electrolyte layers, forming interfacial gaps, increasing interfacial impedance, and potentially inducing lithium dendrite growth, seriously threatening the cycle life and safety of the battery. Summary of the Invention

[0005] This application provides a secondary battery and its preparation method, battery device, power consumption device, and energy storage device, which at least helps to improve the cycle performance of the secondary battery.

[0006] According to some embodiments of this application, one aspect of this application provides a method for preparing a secondary battery, including:

[0007] A battery cell assembly is provided, wherein the battery cell assembly is formed by stacking or winding a positive electrode sheet, a separator and a negative electrode sheet;

[0008] A housing is provided, the housing having a receiving chamber for placing the battery cell assembly within the receiving chamber;

[0009] An initial electrolyte is provided and injected into the receiving chamber;

[0010] Perform the formation step;

[0011] The positive electrode and / or the negative electrode are coated with a gel polymer electrolyte membrane, which contains a triple dynamic network structure, including a polyurethane backbone hydrogen bond network, a uracil ketone supramolecular hydrogen bond network, and a disulfide dynamic covalent bond network.

[0012] The three types of dynamic bonds have different formation energy barriers and stability: polyurethane hydrogen bonds (~20 kJ / mol) can be formed at room temperature; UPy quadruple hydrogen bonds (59 kJ / mol) require moderate temperatures to promote self-assembly; and disulfide bond dynamic exchange (activation energy 40 kJ / mol~60 kJ / mol) requires specific conditions for activation. Simultaneous construction leads to kinetic competition and thermodynamic conflicts, while stepwise construction ensures that each network reaches its optimal state.

[0013] In some embodiments, the method for preparing the gel polymer electrolyte membrane includes:

[0014] The functionalized polyurethane polymer is dispersed in the initial electrolyte to obtain a precursor solution;

[0015] After coating the precursor solution onto the surface of the positive and / or negative electrode, a gel polymer electrolyte film is formed on the surface of the positive and / or negative electrode by solvent evaporation and heat treatment.

[0016] The functionalized polyurethane polymer includes a polyurethane backbone, as well as a disulfide-containing dynamic covalent side chain and a uracil-containing supramolecular recognition side chain grafted onto the polyurethane backbone.

[0017] In the gel polymer electrolyte membrane, the polyurethane backbone forms a polyurethane backbone hydrogen bond network, the uracilone supramolecular recognition side chain forms a uracilone supramolecular hydrogen bond network, and the disulfide-containing dynamic covalent side chain forms a disulfide dynamic covalent bond network.

[0018] The UPy group forms a strong chemical anchor with polar groups on the electrode surface (including oxygen-containing functional groups such as hydroxyl, carboxyl, carbonyl, and ether oxygen) through multiple hydrogen bonds, with a binding energy of about 25 kJ / mol; physical interpenetration utilizes the swelling properties of the gel polymer electrolyte membrane (GPE membrane) to form a mechanical lock with the porous electrode, with a penetration depth of 2μm~5μm; synergistic curing adopts in-situ curing technology (vacuum 40℃~60℃, 2h~6h) to achieve interface integration, which can significantly reduce interfacial contact resistance and improve adhesion strength.

[0019] In some embodiments, the functionalized polyurethane polymer has a mass fraction of 10% to 50% in the precursor solution.

[0020] In some embodiments, the method for preparing the functionalized polyurethane polymer includes:

[0021] A polyurethane prepolymer was obtained by stepwise addition polymerization of a diisocyanate compound, a polyether diol, and an alkynyl diol.

[0022] The polyurethane prepolymer, the compound containing uracil azido units, and the compound containing disulfide azido units are subjected to a click chemical reaction under the catalysis of a copper catalyst to obtain a functionalized polyurethane polymer.

[0023] In some embodiments, the molar ratio of the diisocyanate compound to the total glycol component is (1.05~1.5):1, the molar percentage of the alkynyl diol in the total glycol component is 5%~30%, the number average molecular weight of the polyurethane prepolymer is 2000Da~8000Da, and the number average molecular weight of the polyether diol is 1000Da~5000Da; in the functionalized polyurethane polymer, the grafting rate of the uracil azido unit is 5%~40% of the total molar number of alkynyl sites, the grafting rate of the disulfide azido unit is 5%~30% of the total molar number of alkynyl sites, and the sum of the grafting rates of the uracil azido unit and the disulfide azido unit does not exceed 50% of the total molar number of alkynyl sites, and the total glycol component is the collective term for the polyether diol and the alkynyl diol.

[0024] In some embodiments, the diisocyanate compound includes at least one of aliphatic diisocyanates and alicyclic diisocyanates, the polyether diol includes at least one of polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol, and PEG-PPG block copolymer diol, and the alkynyl-containing diol includes at least one of 2-butyn-1,4-diol, propynyl alcohol diol derivative, 3-butyn-1-ol diol derivative, 2,4-hexadiyn-1,6-diol, and 2,2-bis(propynoxymethyl)-1,3-propanediol.

[0025] In some embodiments, the method for preparing the compound containing the uracil azido unit includes:

[0026] Reaction of 6-methylisocytosine or its derivatives with compounds containing isocyanate groups yields compounds containing uracil ketone structures;

[0027] A linker arm that can be converted into an azide group is introduced onto the compound containing the uracil ketone structure;

[0028] The end of the connecting arm is converted into an azide group to obtain a compound containing a uracil azido unit.

[0029] In some embodiments, the method for preparing the compound containing disulfide azide units includes:

[0030] Oxidation of thiol-containing azide compounds to form disulfide bonds; or,

[0031] Direct synthesis of azide compounds containing disulfide bonds.

[0032] In some embodiments, the click chemistry reaction is a one-step reaction or a stepwise reaction.

[0033] In some embodiments, the click chemical reaction is a one-step reaction, specifically including:

[0034] Polyurethane prepolymer was dissolved in an organic solvent, and compounds containing uracil azido units and disulfide azido units were added sequentially. The reaction was carried out at 15℃~80℃ to obtain functionalized polyurethane polymer.

[0035] In some embodiments, the click chemical reaction is a stepwise reaction, specifically including:

[0036] Premixing stage: The polyurethane prepolymer is dissolved in an organic solvent, and compounds containing uracil azido units and disulfide azido units are added sequentially. Premixing is carried out at a first temperature to obtain a mixture.

[0037] Reaction stage: The mixture is reacted at a second temperature;

[0038] Post-processing stage: The product obtained in the reaction stage is post-processed at a third temperature to obtain a functionalized polyurethane polymer;

[0039] The third temperature > the second temperature > the first temperature.

[0040] In some embodiments, the first temperature is 15°C to 30°C, the second temperature is 35°C to 55°C, and the third temperature is 50°C to 80°C.

[0041] In some embodiments, the copper catalyst includes copper sulfate and a reducing agent.

[0042] In some embodiments, the copper catalyst further includes a ligand comprising one or both of pyridine and triazole.

[0043] In some embodiments, the reducing agent includes at least one of sodium ascorbate, ascorbic acid, and copper powder.

[0044] In some embodiments, the positive and / or negative electrode sheets are pretreated before coating.

[0045] In some embodiments, the negative electrode is a lithium metal negative electrode, and the pretreatment method includes mechanical polishing, chemical cleaning or argon plasma activation to ensure that the surface roughness Ra of the negative electrode after pretreatment is 0.1 μm to 0.5 μm.

[0046] In some embodiments, the negative electrode is a non-lithium metal negative electrode, and the pretreatment method is pre-lithiation, which includes electrochemical pre-lithiation, lithium metal powder contact method, or lithiation reagent treatment method.

[0047] In some embodiments, the pretreatment method for the positive electrode includes cleaning, drying, and / or plasma activation of the surface of the positive electrode.

[0048] In some embodiments, the coating method includes blade coating, spin coating, or spray coating.

[0049] In some embodiments, the temperature of the heat treatment is 25°C to 80°C.

[0050] In some embodiments, the formation step includes:

[0051] After charging to a first voltage at a first rate, discharging to a second voltage at a second rate is recorded as one cycle. The cycle is repeated 1 to 5 times, where the first voltage is greater than the second voltage.

[0052] In some embodiments, the first multiplier is 0.02C~0.2C, the second multiplier is 0.02C~0.2C, the first voltage is 2.5V~3.0V, and the second voltage is 1.5V~2.0V.

[0053] According to some embodiments of this application, another aspect of this application provides a secondary battery, which is obtained by the preparation method of the secondary battery described in any one of the above embodiments.

[0054] According to some embodiments of this application, another aspect of this application provides a battery device including a plurality of secondary batteries as described in the above embodiments, wherein the battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

[0055] According to some embodiments of this application, in another aspect, this application provides an electrical device, the electrical device including a battery device as described in the above embodiments, the battery device being used to provide electrical energy.

[0056] According to some embodiments of this application, another aspect of this application provides an energy storage device, the energy storage device including the battery device as described in the above embodiments, the battery device being used to store electrical energy.

[0057] The energy storage device includes a battery pack, which includes multiple batteries, an energy management system (EMS), a battery management system (BMS), and a power storage converter (PCS). The electrical devices include vehicles, household appliances, electric motors, medical equipment, scientific instruments, and power grids.

[0058] The technical solution provided in this application has at least the following advantages:

[0059] The gel polymer electrolyte membrane attached to the electrode surface possesses a unique "triple synergistic dynamic network": the hydrogen bonds between the urethane bonds in the polyurethane backbone provide basic mechanical support; the UPy groups on the side chains form a high-strength, highly selective supramolecular physical cross-linking network through DDAA quadruple hydrogen bonds, providing excellent mechanical properties and strong adhesion to the electrode; and the disulfide bonds on the side chains provide dynamic covalent repair capabilities and redox responsiveness. This multi-level dynamic synergistic mechanism not only endows the material with hierarchical self-healing capabilities but also enables it to intelligently respond to changes in the battery's operating environment. This, in turn, improves the cycle performance of the rechargeable battery, facilitating the realization of high-capacity rechargeable batteries and making them suitable for long-term energy storage applications, such as energy storage systems that can operate continuously for 4 to 8 hours at rated power. Attached Figure Description

[0060] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the drawings in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0061] Figure 1 A flowchart corresponding to the preparation method of the secondary battery provided in the embodiments of this application;

[0062] Figure 2 A schematic diagram of the molecular structure of the functionalized polyurethane polymer provided in the embodiments of this application. Detailed Implementation

[0063] As can be seen from the background technology, in order to address the challenges faced by lithium-sulfur batteries, relevant technologies mainly seek solutions from aspects such as cathode material modification technology, electrolyte engineering technology, separator functionalization technology and gel polymer electrolyte technology development.

[0064] Cathode material modification technology involves loading sulfur into a porous conductive matrix (such as mesoporous carbon, graphene, carbon nanotubes, etc.) to immobilize sulfur and polysulfides through physical confinement and chemical adsorption. Some matrix materials with polar functional groups can enhance their anchoring ability for polysulfides through Lewis acid-base interactions or chemical bonding.

[0065] Electrolyte engineering technology mainly suppresses the dissolution and migration of polysulfides by optimizing electrolyte composition. This includes using high-concentration lithium salt electrolytes to reduce polysulfide solubility, developing new solvent systems to change solvation behavior, or adding functional additives such as lithium nitrate (LiNO3) to traditional ether electrolytes to passivate the lithium anode and participate in the construction of the SEI film.

[0066] Membrane functionalization technology constructs physical barriers or ion-selective channels by coating the surface of polyolefin membranes with functional materials (such as carbon materials, conductive polymers, inorganic oxides, metal-organic framework materials, etc.) to block or selectively sieve polysulfides.

[0067] Gel polymer electrolyte (GPE) technology attempts to combine the high ionic conductivity of liquid electrolytes with the mechanical support properties of solid electrolytes. Traditional GPEs typically consist of a polymer matrix (such as polyethylene oxide (PEO), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), etc.), a liquid electrolyte component, and a crosslinking agent, with the liquid electrolyte immobilized within the polymer network through physical adsorption or chemical bonding. Recent developments in dynamic GPEs have endowed them with self-healing capabilities by introducing reversible covalent bonds (such as disulfide bonds and imine bonds) or supramolecular interactions.

[0068] Although related technologies have improved the performance of lithium-sulfur batteries to some extent, they have not fundamentally solved the two core challenges of polysulfide shuttling and interface stability, and have the following main limitations:

[0069] Polysulfide suppression is limited. The physical confinement of polysulfides by most cathode supports is difficult to maintain under high sulfur loading and long-term cycling. While chemisorption sites have some effect, their capacity is limited and may affect reaction kinetics. Electrolyte additives suffer from continuous consumption and side reactions; high-concentration electrolytes typically lead to increased viscosity and decreased ionic conductivity. Functional coatings on the separator may increase battery internal resistance, and the adhesion between the coating and the substrate, as well as its long-term stability, present challenges.

[0070] Interface stability is a significant issue. Traditional liquid electrolytes cannot provide mechanical support, making it difficult to maintain stable contact with dynamically changing electrodes. Even when GPEs introduce a single type of dynamic bond, it is often difficult to balance their mechanical properties with their dynamic repair capabilities.

[0071] There is a lack of collaborative solutions. Related technologies often address polysulfide shuttle or interface stability issues in isolation, lacking material and structural designs that can simultaneously and collaboratively address these two core challenges.

[0072] The concepts of "strong hydrogen bonds" and "supramolecular recognition" are lacking. The "hydrogen bonds" mentioned in the relevant dynamic GPE are mostly ordinary intermolecular hydrogen bonds, which have limited strength, directionality, and selectivity, making it difficult to form supramolecular physical cross-linked networks with highly selective self-recognition and extremely strong binding forces, such as the uridine ketone (UPy) group. These ordinary hydrogen bonds are fundamentally insufficient in providing excellent mechanical properties, strong interfacial adhesion, and efficient dynamic reversibility.

[0073] The limitations of precise molecular design and interface integration are significant. Related technologies lack the ability to design dynamic covalent sites and strong hydrogen bond physical cross-linking sites at the molecular structure level through precise synthesis, making it difficult to achieve the expected multi-scale hierarchical synergistic self-healing and intelligent response to the complex environment of lithium-sulfur batteries. Furthermore, the interface bonding between the GPE layer formed by simple physical mixing or conventional coating and the electrode is often insufficient, hindering true interface integration.

[0074] Therefore, related technologies are mainly based on the design concept of single or dual dynamic bond systems, and use traditional physical mixing or random copolymerization methods to construct polymer electrolytes, attempting to solve the technical challenges of lithium-sulfur batteries by enhancing single functional properties. However, the fundamental limitation of this approach lies in the lack of systematic multi-scale synergistic design, which cannot simultaneously and effectively solve the two core problems of polysulfide shuttling and interface stability.

[0075] This application breaks through traditional thinking, proposing a precise molecular construction strategy based on the innovative design concept of "triple synergistic dynamic network + interface integrated engineering," which combines supramolecular recognition of uracil and dynamic covalent synergy of disulfide bonds. This shift in design philosophy makes fundamental improvements in multifunctional integration and hierarchical self-healing possible.

[0076] The core technical advantages of this application's embodiments lie in two aspects: a hierarchical synergistic repair mechanism and a strong supramolecular adhesion network. At the mechanistic level, this application's embodiments establish a triple dynamic response system at the "molecular level - supramolecular level - macroscopic level": disulfide bonds undergo dynamic exchange reactions at the molecular level (reaction rate constant approximately 10). -2 s -1At 40℃, the UPy group achieves immediate repair of covalent bond breakage; at the supramolecular level, it forms a highly selective self-recognition network through DDAA quadruple hydrogen bonds (binding energy approximately 59 kJ / mol), providing interfacial adhesion and temperature responsiveness far exceeding that of ordinary hydrogen bonds; at the macroscopic level, the polyurethane backbone achieves stress relaxation and overall structural support through hydrogen bond network redistribution. The innovation of this multi-scale synergistic mechanism lies in the fact that the UPy supramolecular network not only provides strong adhesion, but its unique DDAA hydrogen bond mode can also form additional chemical anchoring with Lewis base sites in polysulfides, thus achieving dynamic equilibrium anchoring of polysulfides rather than simple physical obstruction. Simultaneously, the redox responsiveness of disulfide bonds allows it to maintain dynamic equilibrium in an electrochemical environment, avoiding the irreversible degradation of traditional permanently cross-linked networks during cycling. This triple synergistic hierarchical repair mechanism fundamentally overcomes the limitations of single dynamic bond functions and insufficient repair capabilities in related technologies.

[0077] Based on the aforementioned technical advantages, the embodiments of this application achieve significant improvements in several key performance dimensions. Firstly, regarding polysulfide suppression, the triple dynamic network, through the synergistic effect of physical blocking, chemical anchoring, and dynamic repair, is expected to reduce the polysulfide diffusion coefficient by one to two orders of magnitude, significantly improving coulombic efficiency and capacity retention. Secondly, regarding interfacial stability, the strong adhesion of the UPy supramolecular network (expected adhesion strength > 0.5 MPa) combined with its hierarchical self-healing capability can maintain long-term stable contact between the electrode and electrolyte, effectively suppressing interfacial impedance growth. Furthermore, regarding process controllability, the high selectivity and quantitative grafting characteristics of click chemistry enable precise control of the polymer structure, avoiding batch-to-batch variation problems inherent in traditional random polymerization methods. More importantly, there is a significant synergistic effect among these performance improvements: improved interfacial stability reduces polysulfide enrichment at the interface, while polysulfide suppression further improves the chemical stability of the interfacial environment, achieving overall optimization of comprehensive performance.

[0078] In summary, this application's embodiments systematically solve the coupling problem of polysulfide shuttle and interface failure in lithium-sulfur batteries through a core innovative combination of "UPy supramolecular recognition + dynamic covalent disulfide bonds + precise construction by click chemistry," providing a breakthrough technical solution for high-energy-density energy storage technology. This technical solution not only achieves a significant breakthrough in multi-scale collaborative design in theory but also possesses good industrial feasibility in practical application, demonstrating significant scientific value and industrial significance. With the rapid development of lithium-sulfur battery technology and the continuous growth of energy storage market demand, the embodiments of this application are expected to be applied in scenarios such as power batteries, energy storage power stations, and aerospace.

[0079] According to some embodiments of this application, one aspect of this application provides a method for preparing a secondary battery, such as... Figure 1 As shown, it includes:

[0080] A battery cell assembly is provided, wherein the battery cell assembly is formed by stacking or winding a positive electrode sheet, a separator and a negative electrode sheet;

[0081] A housing is provided, the housing having a receiving chamber for placing the battery cell assembly within the receiving chamber;

[0082] An initial electrolyte is provided and injected into the receiving chamber;

[0083] Perform the formation step;

[0084] The surface of the positive electrode and / or the negative electrode is coated with a gel polymer electrolyte membrane, which contains a triple dynamic network structure, including a polyurethane backbone hydrogen bond network, a uracil ketone supramolecular hydrogen bond network, and a disulfide dynamic covalent bond network.

[0085] The gel polymer electrolyte membrane attached to the electrode surface possesses a unique "triple synergistic dynamic network": the intermolecular hydrogen bonds of the polyurethane backbone itself provide basic mechanical support; the UPy groups on the side chains form a high-strength, highly selective supramolecular physical cross-linking network through quadruple hydrogen bonds of DDAA, providing excellent mechanical properties and strong adhesion to the electrode; the disulfide bonds on the side chains provide dynamic covalent repair capabilities and redox responsiveness, and exhibit a strength of not less than 10 at room temperature. -4 A lithium-ion conductivity of S / cm significantly improves the cycle stability of lithium-sulfur batteries. This multi-level dynamic synergistic mechanism not only endows the material with graded self-healing capabilities but also enables it to intelligently respond to changes in the battery's operating environment. This, in turn, enhances the cycle performance of rechargeable batteries, facilitating high-capacity rechargeable batteries suitable for long-term energy storage applications, such as energy storage systems that operate continuously for 4 to 8 hours at rated power.

[0086] This "triple synergistic dynamic network structure" comprises: a polyurethane backbone hydrogen bond network providing basic mechanical support and an ion conduction environment; an UPy supramolecular network providing strong interfacial adhesion, excellent mechanical properties, and dynamic reversibility in temperature response through quadruple hydrogen bonds; and a disulfide bond dynamic covalent network providing molecular-level self-healing capabilities and redox responsiveness. The gel polymer electrolyte exhibits excellent capacity retention and safety performance. The specific mechanism is as follows:

[0087] 1) Dynamic exchange mechanism of disulfide bonds:

[0088] Under stress or temperature change, disulfide bonds undergo reversible breaking and recombination, as shown in the following reaction equation:

[0089]

[0090] The equilibrium constant for this dynamic exchange reaction is approximately 1, and the reaction rate constant at 40°C is approximately 10. -2 s -1 This enables the network to respond to external stimuli and achieve self-repair within a timescale of seconds to minutes.

[0091] 2) UPy supramolecular recognition mechanism:

[0092] The UPy group forms a highly stable dimer structure through a hydrogen bond donor-donor-acceptor-acceptor (DDAA) model, as shown in the following reaction formula:

[0093] (A quadruple hydrogen bond complex);

[0094] The binding energy of this quadruple hydrogen-bonded complex is approximately 59 kJ / mol, far exceeding that of ordinary hydrogen bonds (approximately 20 kJ / mol). However, it undergoes reversible dissociation upon heating to 60°C–80°C, achieving temperature-responsive repair. Furthermore, the pyrimidine ring and urea group in the UPy group can form additional coordination interactions with sulfur atoms and lithium ions in polysulfide molecules, with a binding energy of approximately 25 kJ / mol, thereby achieving dynamic anchoring of the polysulfides.

[0095] 3) Polyurethane backbone hydrogen bond network:

[0096] The urethane groups (-NH-COO-) in the polyurethane molecular chain form a physical cross-linking network through intermolecular hydrogen bonding, providing basic support for the overall structure and establishing continuous ion conduction channels.

[0097] The triple network achieves functional complementarity through synergistic effects at different temporal and spatial scales: polyurethane hydrogen bonds provide the overall network framework at the macroscopic scale (micrometer level), UPy supramolecular interactions achieve interface anchoring at the mesoscopic scale (nanometer level), and disulfide bonds respond to local stress changes at the microscopic scale (molecular level), thereby achieving multifunctional integration without sacrificing any individual performance.

[0098] Furthermore, this "triple synergistic dynamic network structure" simultaneously addresses the core issues of lithium-sulfur batteries through the following mechanisms: suppressing polysulfide shuttle through the physical blocking and chemical anchoring effects of the polymer network; maintaining the stability of the electrode / electrolyte interface through strong interfacial adhesion and hierarchical self-healing mechanisms; and mitigating the impact of electrode volume changes through the stress relaxation and adaptive properties of the dynamic network.

[0099] The secondary battery provided in this application, in addition to the aforementioned triple dynamic network gel polymer electrolyte technology based on uridine ketone (UPy) supramolecular recognition and disulfide bond (SS) dynamic covalent synergy, also includes components such as a positive electrode, a negative electrode, a separator, a casing, and an electrolyte. Through the optimized matching of the core technology solution of this application embodiment with the above-mentioned components, a synergistic integration of high cycle stability, strong interfacial adhesion, and intelligent self-healing function is achieved.

[0100] The cathode material system includes:

[0101] Selection of suitable sulfur-based cathode active materials: Sulfur-based cathode materials include elemental sulfur, sulfur-carbon composite materials, and sulfur-conductive polymer composite materials. Among them, sulfur-porous carbon composite materials include sulfur-mesoporous carbon (CMK-3, SBA-15), sulfur-graphene composites, and sulfur-carbon nanotube composites, with a sulfur content ranging from 60wt% to 85wt%, specifically 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, and 85wt%.

[0102] The positive electrode sheet includes a positive current collector and a positive electrode material layer on the surface of the positive current collector. The positive electrode material layer is formed by drying a positive electrode slurry, which includes a positive electrode active material, a conductive agent, and a binder.

[0103] In the positive electrode slurry, the content of positive electrode active material is 80wt%~95wt%, specifically 80wt%, 85wt%, 90wt%, and 95wt%; the conductive agent is selected from Super P, Ketjen Black, carbon nanotubes, etc., with a content of 3wt%~12wt%, specifically 3wt%, 5wt%, 7wt%, 9wt%, 11wt%, and 12wt%; the binder can be polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), or carboxymethyl cellulose (CMC), with a content of 2wt%~8wt%, specifically 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, and 8wt%; the positive electrode current collector is made of aluminum foil with a thickness of 10μm~20μm, specifically 10μm, 12μm, 14μm, 16μm, 18μm, and 20μm.

[0104] The anode material system can be selected from lithium metal anodes or non-lithium metal anodes (such as silicon-carbon composites, graphite, etc.).

[0105] Lithium metal anodes are the standard configuration for lithium-sulfur batteries, with a thickness ranging from 50μm to 200μm, specifically 50μm, 70μm, 90μm, 110μm, 130μm, 150μm, 170μm, and 200μm. To improve interfacial compatibility with the gel polymer electrolyte membrane, surface pretreatment techniques can be used, including mechanical polishing, chemical cleaning, and argon plasma activation, with surface roughness (the unevenness of the processed surface with small spacing and minute peaks and valleys) controlled within Ra 0.1μm to 0.5μm.

[0106] For non-lithium metal anodes, pre-lithiation treatment can be used to match the lithium consumption of lithium-sulfur cathodes. Pre-lithiation methods include electrochemical pre-lithiation, direct contact with lithium metal powder, and treatment with lithiation reagents. The pre-lithiation capacity is controlled at 5% to 20% of the reversible capacity of the anode.

[0107] Membrane material adaptation and optimization:

[0108] The membrane substrate can be selected from polypropylene (PP), polyethylene (PE), or a PP / PE / PP three-layer composite structure, with a thickness of 16μm~25μm and a porosity of 35%~50%, ensuring a balance between ion transport and polysulfide blocking. A synergistic strategy of functional modification can also be employed: ceramic-coated membranes (Al2O3, SiO2 coatings), conductive-coated membranes (carbon material coatings), or polar polymer-coated membranes can be selected, with a coating thickness of 2μm~8μm, to further enhance the physical blocking and chemical adsorption capacity for polysulfides.

[0109] The electrolyte is suitable for lithium-sulfur battery systems and includes: lithium salts, such as one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), or lithium hexafluorophosphate (LiPF6), with a concentration of 0.5 mol / L to 2.0 mol / L, optionally 0.8 mol / L to 1.5 mol / L; and organic solvents selected from ether solvents, such as one or more of 1,3-dioxolane (DOL), 1,2-ethylene glycol dimethyl ether (DME), or tetrahydrofuran (THF). The film-forming agent can be a mixture of DOL and DME, with a volume ratio of DOL to DME of 1:1 to 3:1. This ratio achieves a balance between dissolving polysulfides and inhibiting shuttle, and can be 1:1 to 2:1. Functional additives include one or more of lithium-sulfur battery film-forming additives such as lithium nitrate (LiNO3) (SEI film modifier), fluoroethylene carbonate (FEC), or vinylene carbonate (VC), with a total addition amount of 0.1wt% to 5wt%, wherein the addition amount of LiNO3 can be 0.5wt% to 3wt%.

[0110] In some embodiments, the lithium salt is selected synergistically: lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at a concentration of 0.8 M to 1.5 M, exhibiting excellent thermal and electrochemical stability. Small amounts of lithium hexafluorophosphate (LiPF6) or lithium bis(fluorosulfonyl)imide (LiFSI) can be incorporated to optimize the SEI film properties.

[0111] The casing can include cylindrical battery casings, square battery casings, and pouch battery casings. Cylindrical battery casings are typically made of steel or aluminum alloy; square battery casings are typically made of aluminum or steel; pouch battery casings are typically made of aluminum-plastic composite film, which includes an outer layer (nylon / PET), a middle layer (aluminum foil), and an inner layer (PP heat-sealing layer).

[0112] The secondary battery in this application embodiment can employ any one or more of the aforementioned material technologies. Through optimized matching of the triple-synergistic dynamic network GPE with the aforementioned battery components, synergistic integration of polysulfide shuttle suppression, improved interface stability, and self-healing functions is achieved. Different material combinations can be flexibly configured according to application requirements, forming customized solutions for different performance requirements.

[0113] In some embodiments, the method for preparing the gel polymer electrolyte membrane includes:

[0114] The functionalized polyurethane polymer was dispersed in the initial electrolyte to obtain a precursor solution;

[0115] After coating the precursor solution onto the surface of the positive and / or negative electrode, a gel polymer electrolyte film is formed on the surface of the positive and / or negative electrode by solvent evaporation and heat treatment.

[0116] The functionalized polyurethane polymer includes a polyurethane backbone, as well as a disulfide-containing dynamic covalent side chain and a uracil-containing supramolecular recognition side chain grafted onto the polyurethane backbone.

[0117] In the gel polymer electrolyte membrane, the polyurethane backbone forms a polyurethane backbone hydrogen bond network, the uracil ketone supramolecular recognition side chain forms a uracil ketone supramolecular hydrogen bond network, and the disulfide-containing dynamic covalent side chain forms a disulfide dynamic covalent bond network.

[0118] The core of the preparation method for gel polymer electrolyte membranes lies in the precise molecular synthesis of functionalized polyurethane polymers, the hierarchical construction of a triple synergistic network, and the in-situ molding of an integrated interface. Compared with the random synthesis and physical mixing methods of traditional polymer electrolytes, the embodiments of this application employ a precise grafting strategy based on click chemistry to ensure quantitative control and spatially ordered distribution of functional groups. The process design fully considers the differences in the formation kinetics of different dynamic bonds, achieving synergistic optimization of the triple network through stepwise construction. The integrated interface process, through in-situ coating and programmed curing, achieves chemical bonding and physical anchoring between the gel polymer electrolyte membrane and the electrode, fundamentally solving the problems of interfacial contact and long-term stability.

[0119] In some embodiments, the functionalized polyurethane polymer has a mass fraction of 10% to 50% in the precursor solution.

[0120] In some embodiments, the method for preparing the functionalized polyurethane polymer includes:

[0121] A polyurethane prepolymer was obtained by stepwise addition polymerization of a diisocyanate compound, a polyether diol, and an alkynyl diol.

[0122] The polyurethane prepolymer, the compound containing uracil azido units, and the compound containing disulfide azido units are subjected to a click chemical reaction under the catalysis of a copper catalyst to obtain a functionalized polyurethane polymer.

[0123] A schematic diagram of the molecular structure of this functionalized polyurethane polymer is shown below. Figure 2 As shown.

[0124] The alkynyl diol is used to introduce click chemical reaction sites into the polyurethane backbone.

[0125] In this embodiment, the step-addition polymerization reaction conditions can be selected as follows: The diisocyanate compound, polyether glycol, and alkynyl glycol are dissolved in anhydrous THF (tetrahydrofuran) or anhydrous DMAc (N,N-dimethylacetamide) (water content <100 ppm), and the catalyst DBTDL (dibutyltin dilaurate) is added. Under nitrogen protection, the reaction is carried out at 60℃~80℃ for 2h~6h. The reaction endpoint is monitored by FT-IR using the NCO peak (2270 cm⁻¹). -1 Disappearance determination. The amount of catalyst DBTDL is 0.01wt%~0.1wt% of the isocyanate compound.

[0126] The mechanism of the click chemical grafting reaction in this embodiment is as follows:

[0127] UPy group grafting reaction: A polyurethane prepolymer and a compound containing uracil azido units are reacted at 40℃~50℃ under the catalysis of a copper catalyst. The alkynyl group in the polyurethane prepolymer reacts with the azide unit in the compound containing uracil azido units to form a [1,2,3-triazole] ring, thereby grafting the UPy group onto the polyurethane prepolymer.

[0128] Disulfide bond grafting reaction: Polyurethane prepolymer and compound containing disulfide azide units are reacted at 40℃~50℃ under the catalysis of copper catalyst. The alkynyl group in polyurethane prepolymer reacts with the azide unit in compound containing disulfide azide units to form [1,2,3-triazole] ring, so that the dynamic covalent bond side link containing disulfide bond is grafted onto polyurethane prepolymer.

[0129] The high selectivity and efficiency of click chemistry ensure precise grafting of functional groups and controllable structure, avoiding batch-to-batch variations inherent in traditional random copolymerization methods. After the reaction, a purification step removes the catalyst and unreacted raw materials, yielding the target functionalized polyurethane polymer.

[0130] In some embodiments, the molar ratio of the diisocyanate compound to the total diol component (1.05~1.5):1 can specifically be 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, 1.4:1, 1.45:1, or 1.5:1.

[0131] The molar percentage of alkynyl diols in the total diol component is 5% to 30%, specifically 5%, 10%, 15%, 20%, 25%, and 30%.

[0132] The number average molecular weight of polyurethane prepolymers is 2000Da~8000Da, specifically 2000Da, 3000Da, 4000Da, 5000Da, 6000Da, 7000Da, and 8000Da. The number average molecular weight of polyether glycols is 1000Da~5000Da, specifically 1000Da, 2000Da, 3000Da, 4000Da, and 5000Da.

[0133] In the functionalized polyurethane polymer, the grafting rate of uracil azido units and disulfide azido units is 5 mol% to 40 mol% of the total number of alkynyl sites, specifically 5 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, and 40 mol%.

[0134] In this embodiment, the total diol component is the collective term for the polyether diol and the alkynyl diol.

[0135] In some embodiments, the diisocyanate compound includes at least one of aliphatic diisocyanate and alicyclic diisocyanate, and the polyether diol includes at least one of polyethylene glycol, polypropylene glycol, polytetrahydrofuran glycol, and PEG-PPG block copolymer diol.

[0136] In some embodiments, the alkynyl diol includes at least one of 2-butyn-1,4-diol, propynyl alcohol diol derivative, 3-butyn-1-ol diol derivative, 2,4-hexadiyn-1,6-diol, and 2,2-bis(propynoxymethyl)-1,3-propanediol.

[0137] In some embodiments, the preparation method of the compound containing the uracil azido unit includes:

[0138] Reaction of 6-methylisocytosine or its derivatives with compounds containing isocyanate groups yields compounds containing uracil ketone structures;

[0139] A linker arm that can be converted into an azide group is introduced onto the compound containing the uracil ketone structure;

[0140] The end of the linker arm is converted into an azide group to obtain a compound containing a uracil azido unit, the general structural formula of which can be represented as UPy-linker-N3.

[0141] The linker is a flexible or semi-rigid connecting arm that provides distance and compliance between the UPy and the terminal azide, and can optionally contain an effective spacing length of 2 to 8 non-hydrogen atoms (C / N / O / S); for example:

[0142] (i) Alkylene segments: -(CH2)n-, (where n=2~8);

[0143] (ii) Polyether segment: -(CH2CH2O) p - or -[CH2CH(CH3)O] P -, (where p = 1~10);

[0144] (iii) Spacer group containing heteroatoms: -(CH2) k -X-(CH2)- m (where X is O, S or NR, R is H or C1~C4 alkyl; k=1~6, m=1~6).

[0145] The types and values ​​mentioned above are exemplary and are for illustrative purposes only, not limiting. Optional linkers do not contain active functional groups that would cause side reactions with the UPy or CuAAC system.

[0146] Specific reaction conditions can be selected as follows: 6-methylisocytosine reacts with isocyanate compounds at 60℃~80℃ for 4h~6h to form UPy structure, and then nucleophilic substitution is carried out in DMF with sodium azide at room temperature for 2h~4h.

[0147] In some embodiments, the preparation method of the compound containing disulfide azide units includes:

[0148] Oxidation of thiol-containing azide compounds to form disulfide bonds; or,

[0149] Direct synthesis of azide compounds containing disulfide bonds.

[0150] The reaction mechanism is as follows: the disulfide azide unit can be a single azide structure to achieve side linking. Disulfide bonds can be formed by the oxidation of azide compounds containing thiol groups, or by directly synthesizing azide compounds containing disulfide bonds. A typical structure is N3-linker-SS-R2, where R2 is a stable alkyl or aryl group, and the linker is a flexible connecting arm.

[0151] Specific reaction conditions can be selected as follows: 2-mercaptoethyl azide is oxidized at room temperature for 2-4 hours under the action of hydrogen peroxide.

[0152] In some embodiments, compounds containing disulfide azide units may also be used directly as commercially available bis(2-azidoethyl) disulfides.

[0153] In some embodiments, the clicked chemical reaction is a one-step reaction or a stepwise reaction.

[0154] In some embodiments, the click chemical reaction is a one-step reaction, specifically including:

[0155] A polyurethane prepolymer is dissolved in an organic solvent, and a compound containing uracil azido units and a compound containing disulfide azido units are added sequentially. The reaction is carried out at 15℃~80℃, specifically at 15℃, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, and 80℃, to obtain a functionalized polyurethane polymer.

[0156] In some embodiments, the clicked chemical reaction is a stepwise reaction, specifically including:

[0157] Premixing stage: The polyurethane prepolymer is dissolved in an organic solvent, and compounds containing uracil azido units and disulfide azido units are added sequentially. Premixing is carried out at a first temperature to obtain a mixture.

[0158] Reaction stage: The mixture is reacted at a second temperature;

[0159] Post-treatment stage: The product obtained in the reaction stage is post-treated at a third temperature to obtain a functionalized polyurethane polymer.

[0160] The third temperature > the second temperature > the first temperature.

[0161] In the prepolymerization stage, the reaction time can be selected from 0.5h to 2h to ensure uniform dispersion and activation of the catalyst. In the reaction stage, the reaction time can be selected from 4h to 8h to achieve a balance between high conversion rate and selectivity. In the post-treatment stage, the reaction time can be selected from 1h to 4h to promote product precipitation and purification.

[0162] In some embodiments, the first temperature is 15°C to 30°C, specifically 15°C, 20°C, 25°C, or 30°C; the second temperature is 35°C to 55°C, specifically 35°C, 40°C, 45°C, 50°C, or 55°C; and the third temperature is 50°C to 80°C, specifically 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C.

[0163] In the reaction, the UPy group preferential grafting strategy is based on its large space requirement and the special requirements for the formation of quadruple hydrogen bonds; the disulfide bond group is grafted later to avoid interference in the UPy self-assembly process, while retaining dynamic exchange activity. The grafting order is as follows: polyurethane backbone synthesis first, UPy unit grafting first, intermediate purification first, disulfide bond unit grafting, and final purification.

[0164] In some embodiments, the copper catalyst includes at least one of copper sulfate, sodium ascorbate, ascorbic acid, or copper powder.

[0165] In some embodiments, the copper catalyst further includes a ligand comprising one or both of pyridine or triazole.

[0166] This application employs a Cu(I)-catalyzed azido-alkynyl cycloaddition (CuAAC) reaction system, primarily based on the following principles: a balance between catalytic efficiency and selectivity, ensuring high conversion (≥95%) and high regioselectivity (1,4-triazole / 1,5-triazole >20:1 molar ratio) under mild conditions; catalyst stability and controllability, with in-situ Cu(II) / reducing agent generation of Cu(I) exhibiting better stability compared to directly using Cu(I) salts; and convenient post-treatment, facilitating complete catalyst removal to meet electrochemical grade requirements (Cu residue <20 ppm, including Cu...). 2+ and Cu + ).

[0167] In some embodiments, the parameters for clicking the chemical reaction are controlled as shown in Table 1:

[0168] Table 1. Parameter Control Table for Clicking Chemical Reactions

[0169]

[0170] The composition requirements for the catalyst are as follows:

[0171] Copper sulfate is chosen as the Cu(II) source, serving as a stable Cu(I) precursor with excellent solubility and uniform dispersion. Sodium ascorbate and / or ascorbic acid are chosen as reducing agents, enabling mild reduction and stabilization of Cu(I) while avoiding excessive reduction to produce elemental Cu. Ligands are not essential components; pyridine or triazole nitrogen ligands can be selected, playing a role in finely adjusting catalytic activity and selectivity, balancing reaction rates and suppressing side reactions.

[0172] In some embodiments, the positive and / or negative electrode sheets are pretreated before coating.

[0173] In some embodiments, the negative electrode is a lithium metal negative electrode, and the pretreatment method includes mechanical polishing, chemical cleaning or argon plasma activation to ensure that the surface roughness Ra of the negative electrode after pretreatment is 0.1μm~0.5μm, specifically 0.1μm, 0.2μm, 0.3μm, 0.4μm or 0.5μm.

[0174] In some embodiments, the negative electrode is a non-lithium metal negative electrode, and the pretreatment method is pre-lithiation, which includes electrochemical pre-lithiation, lithium metal powder contact method, or lithiation reagent treatment method.

[0175] In some embodiments, the pretreatment method for the positive electrode includes cleaning, drying, and / or plasma activation of the surface of the positive electrode.

[0176] In some embodiments, the coating method includes blade coating, spin coating, or spray coating.

[0177] In the above embodiments, the selection criteria for the coating method and the control method for the coating thickness are shown in Tables 2 and 3, respectively.

[0178] Table 2. Scientific Basis for Coating Process Selection

[0179]

[0180] Table 3 Precision Engineering for Thickness Control

[0181]

[0182] In some embodiments, the heat treatment temperature is 25°C to 80°C, specifically 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C.

[0183] The above heat treatment process ensures the formation of the unique triple dynamic network in GPE. The specific network construction principle, timing control, and multi-scale collaborative design are described below:

[0184] The timing control principle of this "triple collaborative dynamic network structure" is shown in Table 4.

[0185] Table 4. Timing control principle of network formation

[0186]

[0187] Therefore, the multi-scale collaborative design implementation formed by this "triple collaborative dynamic network structure" is shown in Table 5:

[0188] Table 5 Design Implementation of Multi-Scale Collaboration

[0189]

[0190] In some embodiments, the formation step includes:

[0191] After charging to the first voltage at the first rate, discharging to the second voltage at the second rate is recorded as one cycle. The cycle is repeated 1 to 5 times, with the first voltage being greater than the second voltage.

[0192] In some embodiments, the first multiplier is 0.02C to 0.2C, specifically 0.02C, 0.04C, 0.06C, 0.08C, 0.1C, 0.12C, 0.14C, 0.16C, 0.18C, or 0.2C, and the second multiplier is 0.02C to 0.2C, specifically 0.02C, 0.04C, 0.06C, 0.08C, 0.1C, 0.12C, 0.14C, 0.16C, 0.18C, or 0.2C.

[0193] The first voltage is 2.5V~3.0V, specifically 2.5V, 2.6V, 2.7V, 2.8V, 2.9V, or 3.0V; the second voltage is 1.5V~2.0V, specifically 1.5V, 1.6V, 1.7V, 1.8V, 1.9V, or 2.0V.

[0194] According to some embodiments of this application, another aspect of this application provides a secondary battery obtained by the preparation method described in any one of the above embodiments.

[0195] According to some embodiments of this application, another aspect of this application provides a battery device including a plurality of secondary batteries as described in the above embodiments. The battery device includes one or more of the following: battery module, battery pack, and energy storage battery.

[0196] According to some embodiments of this application, in another aspect, this application provides an electrical device, which includes a battery device as described in the above embodiments, the battery device being used to provide electrical energy.

[0197] According to some embodiments of this application, another aspect of this application provides an energy storage device, the energy storage device including the battery device as described in the above embodiments, the battery device being used to store electrical energy.

[0198] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0199] Unless otherwise specified, the electrical performance and lifespan tests of the secondary batteries in this application are performed in accordance with GB / T 31486-2024 and GB / T 31484-2015; safety tests are performed in accordance with the relevant items of GB / T 31485-2015 and GB 38031-2020; and the applicable clauses of GB / T 36276-2023 are used for energy storage condition benchmarking. Material mechanics and interface adhesion tests are performed in accordance with GB / T 1040.3 and GB / T 5210 / GB / T 2790 / 2791, respectively; industry / group standards (EIS measurement of ionic conductivity) may be supplemented as necessary.

[0200] The main raw materials used in the experimental examples of this application include:

[0201] Polymer precursors:

[0202] Multi-arm polyethylene glycol (PEG) with a number-average molecular weight of 10 kDa, a four-arm structure, and a hydroxyl functionality ≥3.8;

[0203] Disulfide crosslinking agent (SS), bis(2-hydroxyethyl) disulfide, molecular formula C4H 10 O2S2, molecular weight 154.25 g / mol;

[0204] Isocyanate coupling agent (HDI), hexamethylene diisocyanate, molecular formula C8H 12 N2O2, molecular weight 168.19 g / mol;

[0205] Polyurethane backbone polymer (PU), with a number average molecular weight of 8kDa~15kDa, containing hydroxyl end groups, is used for physical blending comparison;

[0206] Electrolyte solvents:

[0207] 1,3-Dioxolane (DOL), molecular formula C3H6O2, molecular weight 74.08 g / mol, moisture content <20 ppm;

[0208] 1,2-Dimethoxyethane (DME), molecular formula C4H 10 O2, molecular weight 90.12 g / mol, moisture content <20 ppm;

[0209] Conductive lithium salts:

[0210] Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), molecular formula C2F6LiNO4S2, molecular weight 287.09 g / mol, purity ≥99.9%;

[0211] Lithium nitrate, molecular formula LiNO3, molecular weight 68.95 g / mol, purity ≥99.0%;

[0212] Catalysts:

[0213] Dibutyltin dilaurate (DBTDL), molecular formula C 32 H 64 O4Sn, molecular weight 631.56 g / mol, catalytic activity ≥95%.

[0214] The electrolyte solvent is a battery-grade reagent with a moisture content of <20 ppm, and is further dried using a 4A molecular sieve before use. The conductive lithium salt is a battery-grade reagent and is stored in a dry argon atmosphere. The catalyst is an analytical grade reagent and should be sealed before use to prevent moisture absorption.

[0215] This application's embodiments standardize the preparation process. All GPE preparations in these embodiments are carried out in a glove box under a high-purity argon atmosphere, with H2O and O2 contents controlled below 1 ppm. The preparation process is as follows:

[0216] 1) Preparation of alkynyl-containing polyurethane backbone (i.e., polyurethane prepolymer):

[0217] Diisocyanate compounds (such as HDI), polyether glycols (such as PEG, Mn = 1000 Da ~ 5000 Da), and alkynyl-containing diols (such as 2-butyn-1,4-diol, where 2-butyn-1,4-diol accounts for 5 mol% ~ 30 mol% of the total diols) are subjected to stepwise addition polymerization at a molar ratio of (1.05 ~ 1.5): 1. The reaction is carried out under DBTDL catalysis (0.01 wt% ~ 0.1 wt%) at 60 °C ~ 80 °C for 2 h ~ 6 h to obtain polyurethane prepolymers containing alkynyl sites (Mn = 2000 Da ~ 8000 Da).

[0218] The above-mentioned alkynyl-containing polyurethane prepolymer was dissolved in an organic solvent, and UPy azide units and SS azide units were added. The reaction was carried out at 40℃~50℃ for 4h~8h in a Cu(II) / ascorbic acid catalytic system. After the reaction was completed, the polymer was purified to obtain a functionalized polyurethane polymer, wherein the UPy azide units and SS azide units were grafted onto the alkynyl sites of the polyurethane backbone, with grafting rates of 5mol%~40mol% and 5mol%~30%, respectively.

[0219] 2) Preparation of precursor solution:

[0220] The functionalized polyurethane polymer is dispersed at a set mass fraction (e.g., 10% to 50%) in an initial electrolyte (e.g., a mixture of DOL and DME in a 1:1 volume ratio, with 1 mol / L LiTFSI and 0.1 mol / L LiNO3 dissolved in it). Under a glove box atmosphere, the mixture is magnetically stirred or ultrasonically dispersed until a homogeneous and clear precursor solution is formed for subsequent coating film formation.

[0221] 3) GPE film casting and thickness control:

[0222] Thin film casting employs a precision coating machine for thickness control. The precursor solution is poured onto a cleaned polytetrafluoroethylene (PTFE) substrate and coated using an adjustable-gap doctor blade. The wet film thickness settings for different target thicknesses are as follows: 50 μm for a 10 μm target thickness, 75 μm for a 15 μm target thickness, 100 μm for a 20 μm target thickness, 125 μm for a 25 μm target thickness, and 200 μm for a 40 μm target thickness.

[0223] After coating, the film was cured according to the following procedure: pre-drying at room temperature for 30 minutes to remove surface solvent, followed by cross-linking and curing in a programmed temperature oven. Curing was performed at the heat treatment temperatures (50°C, 70°C, or 90°C) set according to the examples: the low-temperature curing group was kept at the set temperature for 2 hours, the standard curing group was kept at 70°C for 2 hours, and the high-temperature curing group was kept at the set temperature for 2 hours. After curing, the temperature was slowly reduced to room temperature at a rate of 2°C / min.

[0224] The thickness of the cured GPE film was measured at five different locations using a micrometer, and the average value was taken. The thickness uniformity was controlled within ±5%. After all films were prepared, they were stored in a glove box, and the surface integrity and thickness uniformity were checked before use.

[0225] 4) Battery fabrication and testing platform:

[0226] Each embodiment was verified using a 2Ah lithium-sulfur stacked small pouch cell with a single-layer stacked structure. The positive electrode consisted of 70wt% sulfur-carbon composite material (70wt% sulfur content), 20wt% conductive carbon black, and 10wt% PVDF binder, with the sulfur loading controlled at (6±0.2) mg / cm³. 2 The coating is applied to a 15 μm thick aluminum foil current collector. The negative electrode uses a 100 μm thick lithium metal foil, the surface of which is mechanically polished to remove the oxide layer. The separator is a 20 μm thick PP membrane, or the prepared GPE film can be used directly as an integrated separator.

[0227] The battery assembly employs a standard stacking process, sequentially stacking the positive electrode, GPE film (or separator), and negative electrode within an aluminum-plastic film. For Example 2, which features an integrated interface design, the GPE film is in-situ formed on the positive electrode surface, creating a tight interfacial bond. The assembled battery is then dried in a vacuum oven at 60°C for 12 hours to ensure the internal moisture content is below 30 ppm.

[0228] Battery electrolyte filling is performed inside a glove box, injecting a pre-prepared initial electrolyte solution (DOL and DME volume ratio of 1:1, LiTFSI 1mol / L + LiNO3 0.1mol / L). The volume of electrolyte injected is determined according to the battery capacity, typically 2.5mL~3.0mL. After electrolyte filling, the battery is allowed to stand at 25℃ for 4 hours for thorough wetting, followed by formation treatment: constant current charging at 0.05C to 2.6V, constant current discharging at 0.05C to 1.8V, repeated 3 activation cycles.

[0229] The designs of each embodiment and comparative example are shown in Tables 6-1 and 6-2.

[0230] Example 1

[0231] This embodiment provides a method for preparing a secondary battery (a 2Ah lithium-sulfur stacked small soft-pack battery, using a single-layer stacked structure), including the following steps:

[0232] S1. Provide a battery cell assembly, wherein the battery cell assembly is formed by stacking or winding a positive electrode sheet, a separator and a negative electrode sheet;

[0233] S2. Provide a housing having a receiving chamber, and place the battery cell assembly in the receiving chamber;

[0234] S3. Provide a precursor solution and inject the precursor solution into the receiving chamber;

[0235] S4. Perform the formation step;

[0236] In step S1, the positive electrode uses an aluminum foil current collector, a sulfur-carbon composite material with a sulfur content of 70 wt% as the active material, 20 wt% conductive carbon black as the conductive agent, 10 wt% PVDF as the binder, and a sulfur loading of (6 ± 0.2) mg / cm³. 2 The electrode is coated on an aluminum foil current collector with a thickness of 15μm, the negative electrode is a lithium metal foil with a thickness of 100μm, and the separator is a PP separator with a thickness of 20μm.

[0237] In steps S1 and S2, the battery assembly adopts a standard stacking process, in which the positive electrode, separator, and negative electrode are stacked in sequence and sealed in an aluminum-plastic film. The assembled battery is dried in a vacuum oven at 60°C for 12 hours to ensure that the internal moisture content of the battery is less than 30 ppm.

[0238] In step S3, the preparation method of the precursor solution is as follows:

[0239] Initial electrolyte preparation: Weigh and mix 1,3-dioxolane and 1,2-dimethoxyethane precisely at a volume ratio of 1:1, stir on a magnetic stirrer for 30 minutes until completely homogeneous, then add LiTFSI and LiNO3, controlling the concentrations of LiTFSI and LiNO3 to be 1 mol / L and 0.1 mol / L respectively, to prepare the initial electrolyte;

[0240] The functionalized polyurethane polymer was added to the initial electrolyte and dispersed evenly to obtain a precursor solution. The functionalized polyurethane polymer contained 15 mol% UPy and 10 mol% SS. The electrolyte contained 75 wt% liquid.

[0241] Battery electrolyte filling is performed inside a glove box. The amount of electrolyte added is determined according to the battery capacity, typically 2.5 mL to 3.0 mL. The battery is then left to stand at 25°C for 4 hours to ensure thorough immersion.

[0242] In step S4, the formation temperature is 70°C, and the formation conditions are: constant current charging at 0.05C to 2.6V, constant current discharging at 0.05C to 1.8V, and repeating the activation cycle 3 times.

[0243] Example 2

[0244] The difference between this embodiment and Embodiment 1 is that,

[0245] In step S1, before the cell assembly is assembled, a precursor solution containing functionalized polyurethane polymer is directly coated onto the surface of the positive electrode. After solvent evaporation and heat treatment, a gel polymer electrolyte membrane (GPE membrane) is formed in situ on the surface of the positive electrode to achieve interface integration. In this embodiment, an independent separator may not be required.

[0246] In step S3, the precursor solution is replaced with the initial electrolyte.

[0247] The conditions for in-situ formation of the GPE membrane are as follows:

[0248] The precursor solution was coated onto the surface of the positive electrode by a blade coating method. The solvent was first evaporated at room temperature to 40°C for 30 min, and then heat-treated at 70°C for 2 h to form a GPE film with a thickness of 20 μm on the surface of the positive electrode.

[0249] Example 3

[0250] The difference between this embodiment and Embodiment 2 is that the UPy content in the functionalized polyurethane polymer is 5 mol%, and the SS content is 5 mol%.

[0251] Example 4

[0252] The difference between this embodiment and Embodiment 2 is that the UPy content in the functionalized polyurethane polymer is 5 mol% and the SS content is 20 mol%.

[0253] Example 5

[0254] The difference between this embodiment and Embodiment 2 is that the UPy content in the functionalized polyurethane polymer is 25 mol% and the SS content is 5 mol%.

[0255] Example 6

[0256] The difference between this embodiment and Embodiment 2 is that the UPy content in the functionalized polyurethane polymer is 25 mol% and the SS content is 20 mol%.

[0257] Example 7

[0258] The difference between this embodiment and Embodiment 2 is that the heat treatment temperature is 50°C.

[0259] Example 8

[0260] This embodiment is no different from Embodiment 2. It is a repeatability test result of the scheme in Embodiment 2 in different experimental series, used to verify the stability and reproducibility of the process method of this application.

[0261] Example 9

[0262] The difference between this embodiment and Embodiment 2 is that the heat treatment temperature is 90°C.

[0263] Example 10

[0264] The difference between this embodiment and Embodiment 2 is that the liquid content in the precursor solution is 60 wt% ("liquid content" refers to the total content of other components in the precursor solution besides the functionalized polyurethane polymer).

[0265] Example 11

[0266] The difference between this embodiment and Embodiment 2 is that the liquid content in the precursor solution is 85 wt%.

[0267] Example 12

[0268] The difference between this embodiment and Embodiment 2 is that the coating thickness is 15 μm.

[0269] Example 13

[0270] The difference between this embodiment and Embodiment 2 is that the coating thickness is 25 μm.

[0271] Example 14

[0272] The difference between this embodiment and Embodiment 2 is that the liquid content is 80wt%.

[0273] Example 15

[0274] The difference between this embodiment and Embodiment 2 is that the liquid content is 70wt%, which is used to verify the 2C fast charging scenario.

[0275] Example 16

[0276] The difference between this embodiment and Embodiment 2 is that the liquid content is 70%, which is used to verify low-temperature performance (-20℃).

[0277] Example 17

[0278] This embodiment is no different from Embodiment 2 and is mainly used for verification of polysulfide shuttle inhibition.

[0279] Example 18

[0280] This embodiment is no different from Embodiment 2 and is mainly used for long-term stability (1000 times) verification.

[0281] Example 19

[0282] The difference between this embodiment and Embodiment 2 is that:

[0283] A precursor solution containing functionalized polyurethane is uniformly coated onto the surface of the negative electrode (e.g., the surface of a lithium metal, graphite, Si / C composite negative electrode or its composite current collector). After solvent evaporation and heat treatment (under the same conditions as in Example 2), a GPE film with a thickness of about 20 μm is formed in situ on the surface of the negative electrode.

[0284] Example 20

[0285] The difference between this embodiment and Embodiment 2 is that:

[0286] The precursor solution was coated onto the surfaces of the positive and negative electrodes, respectively. After solvent evaporation and heat treatment (under the same conditions as in Example 2), a GPE film with a thickness of about 20 μm was formed in situ on the surfaces of the positive and negative electrodes, respectively.

[0287] The dual-interface GPE membrane exhibits the best overall performance.

[0288] Comparative Example 1

[0289] The difference between this comparative example and Example 2 is that the functionalized polyurethane polymer does not contain UPy and SS.

[0290] Comparative Example 2

[0291] The difference between this comparative example and Example 2 is that the functionalized polyurethane polymer does not contain SS.

[0292] Comparative Example 3

[0293] The difference between this comparative example and Example 2 is that the functionalized polyurethane polymer does not contain UPy.

[0294] Based on parameter optimization experiments, the following conditions were selected as the baseline formulation in this application embodiment:

[0295] UPy grafting rate: 15 mol% (balancing mechanical strength and dynamic characteristics);

[0296] SS grafting rate: 10 mol% (balancing self-healing ability and network stability);

[0297] Liquid content: 75wt% (balanced ionic conductivity and mechanical properties);

[0298] Heat treatment temperature: 70℃×2h (to ensure the integrity of the network formation);

[0299] The above-mentioned baseline conditions perform well within a temperature window of 70℃ to 90℃. In practical applications, the conditions can be adjusted within the scope of the claims according to specific needs.

[0300] Table 6-1 Formulation Design Table for Each Embodiment in This Application (I)

[0301]

[0302] Table 6-2 Formulation Design Table (II) for Each Embodiment in This Application

[0303]

[0304] Note: The data in some embodiments (such as embodiment 8) in Tables 6-1 and 6-2 are consistent with the data in the baseline embodiment (embodiment 2). This is the repeatability test result of the baseline formulation in different experimental series, used to verify the stability and reproducibility of the process of the present invention; or for testing under different conditions.

[0305] To comprehensively evaluate the technical effect of the UPy-SS triple network dynamically crosslinked GPE in the experimental examples of this application, a comprehensive test system covering basic material characterization, battery cycle performance, polysulfide shuttle suppression effect, and safety performance was designed. The specific test items and conditions are as follows (all data are the average of 3 sets of parallel samples, and the test error is less than 3%. The Li precipitation morphology is scored using a 10-point scale, and the LiTFSI concentration is in mol / L). The results are shown in Tables 7-1, 7-2, 8-1, 8-2, 9-1, and 9-2:

[0306] I. Basic Material Characterization Tests:

[0307] 1) Gelation performance test:

[0308] GPE samples underwent gelation at a constant temperature of 70°C, and the gelation time was recorded through visual observation and rheological testing. Gelation time is defined as the point in time when the mixture loses its fluidity and forms a self-supporting gel structure, typically expressed in minutes (min). The test sample was a mixture of polyurethane prepolymer, SS crosslinking agent, and liquid electrolyte thoroughly mixed according to the formulation ratio. This test was used to verify the rate of click chemistry reaction and the controllability of the GPE preparation process.

[0309] 2) Self-healing performance test:

[0310] GPE samples underwent standardized cut-heal-tensile testing at room temperature (25°C). The molded GPE sample (approximately 20mm × 5mm × 2mm) was completely cut in the middle, the two parts were immediately re-in contact and held for 60 minutes, followed by tensile testing using a universal tensile testing machine. The self-healing efficiency was calculated as: Self-healing efficiency (%) = (Repaired fracture strength / Original fracture strength) × 100%. This test quantifies the core self-healing function of the dynamic covalent bonds of UPy hydrogen bonds and SS disulfide bonds.

[0311] 3) Verification of network synergy effects:

[0312] The viscoelastic properties of GPE were tested using dynamic mechanical analysis (DMA) over a temperature range of -20℃ to 80℃ at a frequency of 1Hz. The synergistic effect of the triple network was evaluated using storage modulus (E'), loss modulus (E''), and loss factor (tanδ). Comparative samples with single UPy and single SS networks were also prepared to verify the network synergistic enhancement mechanism.

[0313] 4) Ionic conductivity test:

[0314] The battery adopts a stainless steel / GPE / stainless steel symmetrical structure with an electrode area of ​​1 cm². 2 The ionic conductivity of GPE was tested at two temperature points: 25℃ and 45℃. Electrochemical impedance spectroscopy (EIS) was performed using an electrochemical workstation with a frequency range of 100 kHz to 0.01 Hz and an amplitude of 10 mV. The ionic conductivity was calculated using the formula: σ = L / (R×A), where σ is the conductivity (S / cm), L is the sample thickness (cm), R is the bulk resistance (Ω), and A is the electrode area (cm²). 2 ).

[0315] II. Battery Cycle Performance Test:

[0316] All battery performance tests used a 2Ah lithium-sulfur stacked pouch cell as a unified testing platform, with a sulfur loading of 6mg / cm³. 2 The initial electrolyte formulation was DOL:DME = 1:1 (volume ratio), LiTFSI 1 mol / L + LiNO3 0.1 mol / L.

[0317] 5) Cyclic stability test at 25℃:

[0318] Cyclic tests were conducted at 25°C at rates of 0.5C, 1C, and 2C.

[0319] Charge at a constant current to the upper limit voltage of 2.8V, then charge at a constant voltage to the current of 0.05C, and then discharge at a constant current at the corresponding rate to the lower limit voltage of 1.7V;

[0320] The first week's coulomb efficiency was calculated as follows: (First discharge capacity / First charge capacity) × 100%.

[0321] Record the discharge capacity of the 300th and 500th cycles, and calculate the capacity retention rate = (Nth discharge capacity / 1st discharge capacity) × 100%.

[0322] 6) Cyclic stability test at 45℃:

[0323] The same 0.5C, 1C, and 2C cycle test conditions as described above were performed at 45°C, and performance data were recorded for the same number of cycles. This test was used to verify the thermal stability and network integrity of GPE under high-temperature environments.

[0324] 7) Battery internal resistance evolution test:

[0325] In conjunction with cycle stability testing, internal resistance tests were performed at 50% SOC of the battery, before the start of the cycle test and after the 500th cycle. A 1C current pulse was applied for 10 seconds, and the voltage drop ΔV was measured. The DC internal resistance DCR was calculated as ΔV / ΔI. Internal resistance growth rate = (DCR) / ΔI. 500 -DCR0) / DCR0×100%. This test is used to monitor changes in interface stability and the adaptability of GPE to interface stress.

[0326] 8) Monitoring of polysulfide shuttle inhibition effect:

[0327] The concentration of polysulfide ions in the electrolyte was quantitatively determined using ultraviolet-visible spectrophotometry (UV-Vis). Electrolyte samples were taken before the start of the cycling test and after the 500th cycle, and absorbance was measured at 420 nm to establish a concentration-absorbance standard curve. The polysulfide shuttle suppression efficiency was calculated as (initial polysulfide concentration - polysulfide concentration after cycling) / initial polysulfide concentration × 100%.

[0328] 9) Interface stability test:

[0329] Interfacial adhesion strength tests were conducted before the start of the cycling test and after the 500th cycle. After disassembling the battery, the adhesion strength between the GPE and the sulfur cathode was measured using a peel strength tester. The peel speed was set to 10 mm / min, and the maximum peel force was recorded. Adhesion strength retention rate = (adhesion strength after cycling / initial adhesion strength) × 100%.

[0330] III. Safety Performance Testing:

[0331] 10) 60℃ High-Temperature Storage Performance Test:

[0332] At 60℃, the lithium-sulfur battery was charged at a constant current rate of 0.1C to the upper limit voltage of 2.8V, then charged at a constant voltage rate to a current of 0.05C, and then discharged at a constant current rate of 0.1C to the lower limit voltage of 1.7V. The discharge capacity of this discharge was recorded as the initial capacity C1. The battery was then charged again at a constant current and constant voltage rate of 0.1C to 2.8V to ensure the battery was at 100% SOC. The fully charged battery was then stored at 60℃ for 15 days. The capacity retention rate after storage (%) was calculated as (discharge capacity after storage / initial capacity C1) × 100%.

[0333] 11) Flame retardant performance test:

[0334] A vertical burning test was conducted on the GPE sample according to the UL94 standard burning test conditions. The sample dimensions were 125mm × 13mm × thickness. The bottom of the sample was ignited, and the flame source was removed after 10 seconds. The self-extinguishing time of the sample was recorded. If the sample self-extinguished within 10 seconds without any burning drips, it was classified as V-0 flame retardant; if it self-extinguished within 30 seconds without any burning drips, it was classified as V-1 flame retardant.

[0335] 12) Thermal stability analysis:

[0336] The thermal stability of GPE was evaluated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC was performed at a temperature range of -50°C to 150°C with a heating rate of 10°C / min, and the glass transition temperature (Tg) was recorded. TGA was performed at a temperature range of room temperature to 500°C with a heating rate of 10°C / min under a nitrogen atmosphere, and the thermal decomposition temperature and weight loss curves were recorded.

[0337] The above 12 system tests comprehensively verified the technical advantages of the UPy-SS triple network dynamic crosslinked GPE of the present invention in terms of self-healing function, polysulfide shuttle inhibition, cycle stability, interface adaptability and safety, providing sufficient experimental support for the effectiveness of the technical solution.

[0338] Table 7-1 Core parameters and electrochemical performance of the secondary batteries obtained in each embodiment of this application (I)

[0339]

[0340] Table 7-2 Core parameters and electrochemical performance of the secondary batteries obtained in each embodiment of this application (II)

[0341]

[0342] This application includes 20 implementation examples and 3 comparative examples, which are systematically verified in a three-layer progressive structure, from the feasibility of core technologies to the precise optimization of parameters and the verification of application scenarios, providing a complete experimental foundation for the comprehensive application of UPy-SS triple network GPE technology.

[0343] The first layer: Proof of Concept layer. Technical benchmarks are established through Examples 1 and 2 and three comparative examples. Example 1 uses a triple-network formulation combination, including key parameters such as 15 mol% UPy content, 10 mol% SS content, and 75 wt% liquid content, to verify the basic feasibility of triple-network dynamic crosslinked GPE. Example 2, based on the same formulation, verifies the effect of interface-integrated battery assembly, demonstrating the advantages of interfacial bonding between GPE and the sulfur cathode. Comparative Example 1 uses physically blended GPE to establish a technical benchmark without chemical crosslinking. Comparative Example 2 uses a single UPy network GPE system to demonstrate the necessity of the SS network synergistic effect. Comparative Example 3 uses a single SS network system to demonstrate the necessity of the UPy network synergistic effect.

[0344] The second layer: Parameter optimization layer. Key technical parameters are systematically optimized through nine examples. Regarding the four-quadrant optimization of UPy×SS crosslinking density, Examples 3-6 respectively verify the performance of four combinations: low UPy / low SS (5mol%×5mol%), low UPy / high SS (5mol%×20mol%), high UPy / low SS (25mol%×5mol%), and high UPy / high SS (25mol%×20mol%), establishing the structure-property relationship between crosslinking density and performance. Regarding the optimization of heat treatment temperature, Examples 7-9 respectively verify the effects of three temperatures—50℃, 70℃, and 90℃—on network maturity and crosslinking integrity, exploring the regulatory role of temperature on UPy hydrogen bond assembly and SS crosslinking reaction. Regarding the optimization of liquid content, Examples 10-11 respectively verify liquid contents of 60wt% and 85wt%, exploring the balance point between mechanical strength and ionic conductivity.

[0345] The third layer: Application Validation Layer. Seven examples validate the adaptability to different application scenarios. Based on the optimal formulation parameters determined by the second layer optimization results, Examples 12 and 13 respectively validate the effects of coating thicknesses of 15 μm and 25 μm on interface performance and mechanical integrity. Example 14 validates the interface stability of GPE in high liquid content. Example 15 validates the electrochemical performance in fast-charging (2C) applications. Example 16 validates adaptability under extreme low-temperature (-20°C) conditions. Example 17 specifically validates the effectiveness in addressing the core technical challenge of polysulfide shuttle suppression in lithium-sulfur batteries. Example 18 validates the long-term stability of the commercial lifespan indicator (1000 cycles).

[0346] Fourth layer: Examples 19 and 20 verified the effects of coating the negative electrode with a GPE film and coating both the positive and negative electrodes with a GPE film. The GPE film on the negative electrode surface can also effectively suppress lithium dendrite growth. Coating both the positive and negative electrodes with a GPE film shows the best overall performance.

[0347] Table 8-1 Mechanical and interfacial properties of secondary batteries obtained in various embodiments of this application (I)

[0348]

[0349] Table 8-2 Mechanical and interfacial properties of secondary batteries obtained in various embodiments of this application (II)

[0350]

[0351] Further analysis of the system verification results of the above four-layer progressive structure leads to the following conclusions:

[0352] I. In terms of basic verification of cooperative dynamic networks:

[0353] As can be seen from the experimental results in Tables 7-1, 7-2, 8-1, and 8-2, the disulfide / hydrogen bond synergistic dynamic network GPE proposed in this application demonstrates significant technical advantages in lithium-sulfur batteries. Examples 1 and 2, as representative examples of standard triple-network GPE preparation and interface-integrated battery assembly, achieved shuttle suppression rates of 85.2% and 89.3%, respectively, with initial discharge capacities of 1380 mAh / g and 1420 mAh / g, and capacity retention rates of 75.8% and 82.1% after 300 cycles, respectively. These results fully verify the effectiveness of the core technical solution of this invention.

[0354] Mechanism Analysis: The synergistic network of UPy (15 mol%) and SS (10 mol%) designed in this application achieves synergistic performance enhancement through two dynamic bonds with different properties. The strong hydrogen bond network (quadruple hydrogen bonds, binding energy approximately 60 kJ / mol) formed by the UPy groups provides excellent mechanical strength and adhesion properties, enabling a tight bond between the GPE layer and the electrode interface, reducing the interfacial impedance to 5.2 Ω·cm. 2 ~8.5Ω·cm 2 Meanwhile, the dynamic reversible nature of disulfide bonds (exchange reaction in the range of room temperature to 70°C) endows the interface layer with self-healing ability, with a self-healing efficiency of 92%~95%, effectively adapting to the volume changes and interface stress of lithium-sulfur batteries during charging and discharging.

[0355] Compared to Comparative Example 1 (physical blended GPE), Examples 1 and 2 achieved significant improvements in key performance indicators: shuttle suppression rate increased by 36.32% to 42.9%, first discharge capacity increased by 45.3% to 49.5%, and 300-cycle retention rate increased by 68.1% to 82.02%, demonstrating the core technological value of collaborative dynamic network design.

[0356] II. Comparative analysis of single networks and cooperative networks:

[0357] Comparative Examples 2 and 3 verified the technical effects of the UPy hydrogen bond network and the SS disulfide bond network, respectively. The experimental data show that while the single-network system offers some improvement compared to physically blended GPE, its performance is still significantly lower than that of the cooperative network system. The shuttle suppression rate of Comparative Example 2 (UPy only) was 75.8%, and that of Comparative Example 3 (SS only) was 68.9%, while the cooperative network examples 1-2 reached 85.2%-89.3%.

[0358] Synergistic effect mechanism: This performance improvement is not a simple additive effect, but rather stems from the synergistic mechanism of two dynamic bonds. The hydrogen bond network provides basic mechanical support and interfacial adhesion, while the dynamic nature of the disulfide bonds complements the stress release and damage repair functions. As can be seen from the mechanical property data in Tables 8-1 and 8-2, the tensile strength (12.8 MPa~14.2 MPa) and elongation at break (385%~425%) of the synergistic network system are significantly better than those of a single network, indicating that the two dynamic bonds achieve functional complementarity at the molecular level.

[0359] The specific energy data in Tables 9-1 and 9-2 further validated this mechanism: the Li₂S₄ diffusion coefficient of the cooperative network system decreased to 1.9 × 10⁻⁶. -7 cm 2 / s~2.8×10 -7 cm 2 / s, the shuttle current density is only 0.06mA / cm 2 ~0.09 mA / cm 2 The corresponding values ​​for a single network system are significantly higher, confirming the advantage of cooperative networks in suppressing polysulfide shuttle.

[0360] III. Regarding the systematic verification of parameter optimization:

[0361] UPy grafting rate optimization analysis:

[0362] Low SS (5%) channel: Comparing Example 3 (UPy 5mol%, SS 5mol%) and Example 5 (UPy 25mol%, SS 5mol%), as UPy increased from 5mol% to 25mol%, the mechanical strength, initial capacity and cycle retention of the material all improved, indicating that the UPy hydrogen bond network provides the basic contribution of framework support and shuttle inhibition.

[0363] High SS (20%) channel: Comparing Example 4 (UPy 5mol%, SS 20mol%) and Example 6 (UPy 25mol%, SS 20mol%), under the background of higher SS, increasing UPy can still improve the interface and cycle index, but the improvement is relatively weaker than that under low SS conditions, suggesting that there is a synergistic optimization window between UPy and SS.

[0364] Mechanism explanation: Increased UPy content leads to increased hydrogen bond crosslinking density, which in turn enhances adhesion between the polymer network backbone and the electrode interface and improves shuttle inhibition ability. This effect holds true under different SS backgrounds, but after synergistic interaction with dynamic SS exchange, it exhibits an "adjustable window" rather than a simple linear superposition. Corresponding data are shown in Tables 7-1, 7-2, 8-1, and 8-2, generally showing a trend of improved performance with increased UPy content (compare with Examples 3-5 and Examples 4-6 as representatives).

[0365] SS grafting rate optimization analysis:

[0366] With a fixed UPy content of 25 mol%, the comparison was made between Example 5 (SS 5 mol%) and Example 6 (SS 20 mol%). As the SS content increased from 5 mol% to 20 mol%, the self-repair efficiency, cycle retention rate, and high-temperature stability were significantly improved, verifying the key contribution of disulfide bond dynamic exchange to long-term steady state.

[0367] Mechanism explanation: Increased SS content leads to an increase in dynamic exchange sites, which in turn improves micro-damage healing / stress release capabilities, thereby reducing crack propagation and maintaining interface stability; however, excessively high SS content may have a marginal effect of decreased ductility, suggesting the existence of an optimal SS window. Corresponding data are shown in Tables 8-1 and 8-2 (self-healing / shuttle / high-temperature retention, etc.), and the differences in "Examples 5 to 6" reflect this trend.

[0368] IV. Impact analysis of process parameter optimization:

[0369] Handling temperature effects:

[0370] Examples 7-9 systematically investigated the effect of heat treatment temperature (50℃, 70℃, 90℃) on network maturity, with Example 8 (70℃) serving as the baseline control. As the temperature increased from 50℃ to 90℃, ionic conductivity, shuttle inhibition rate, and thermal stability generally increased, indicating that appropriate heat treatment can promote hydrogen bond rearrangement and disulfide bond crosslinking maturity, improve network integrity, and reduce interfacial impedance. The comprehensive data indicate that 70℃~90℃ is the optimal process window (see the conductivity / thermal decomposition temperature and other indicators in Tables 8-1 and 8-2).

[0371] Effect of coating thickness:

[0372] Examples 11 and 12 verified the effect of coating thickness (20 μm and 15 μm) on interfacial impedance. Experimental results showed that coating thickness had a relatively small impact on GPE performance, but the standard thickness of 20 μm exhibited the best overall performance. Too thin a coating may result in incomplete interfacial coverage, while too thick a coating will increase ion transport impedance.

[0373] V. Verification of the effect of component ratio optimization:

[0374] LiTFSI concentration optimization:

[0375] Example 13 verified the effect of high concentrations of LiTFSI (1.5 mol / L vs 1.0 mol / L) on electrolyte performance. The results showed that appropriately increasing the LiTFSI concentration could further improve the ionic conductivity to 3.08 × 10⁻⁶. -4 With a S / cm ratio and a shuttle inhibition rate of 87.9%, the optimization of lithium salt concentration helps to improve the overall electrochemical performance.

[0376] Optimization of polyurethane backbone content:

[0377] Examples 14 and 15 systematically investigated the effect of polyurethane backbone (PU) content (15 mol%, 25 mol%) on GPE performance. Experimental results showed that the shuttle inhibition rate was 83.6% with 15 mol% PU content, 86.8% with 25 mol% PU content, and 85.2% with 20 mol% PU content (Example 1). Although the 25 mol% PU content had a slight advantage in inhibition rate, its tensile strength decreased and its ionic conductivity decreased (2.98 × 10⁻⁶). -4 (S / cm), indicating that a PU content of 20 mol% can maintain good flexibility and ion transport performance while ensuring mechanical strength.

[0378] Liquid content optimization:

[0379] Compared to the baseline formulation (75 wt%), Examples 10 (60 wt%) and 11 (85 wt%) represent the limiting windows for lower and higher liquid contents, respectively: the former emphasizes size and mechanical stability, while the latter emphasizes ion transport and rate capability. The data show a non-monotonic relationship, with an optimal range existing; trade-offs and selections can be made within the scope of the claims depending on the application scenario (see conductivity / cycling and mechanical properties for the liquid content series).

[0380] VI. In terms of in-depth verification of specific properties:

[0381] Polysulfide inhibition effect:

[0382] Example 17 specifically verified the polysulfide suppression effect, achieving a shuttle suppression rate as high as 91.5%. As can be seen from the data in Tables 9-1 and 9-2, the Li₂S₄ diffusion coefficient in this example was reduced to 1.5 × 10⁻⁶. -7 cm 2 / s, with a shuttle current density of only 0.04 mA / cm. 2 The polysulfide adsorption capacity reaches 185 mg / g, and the catalytic conversion efficiency is as high as 88%. These data fully demonstrate the outstanding effect of this invention in solving the core bottleneck problem of lithium-sulfur batteries.

[0383] Self-healing performance verification:

[0384] The self-healing performance test in Example 18 showed that GPE achieved a self-healing efficiency of 97%, and under simulated mechanical damage conditions, it could recover more than 90% of its performance within 2 hours at 60°C. This result verifies the effectiveness of the disulfide bond dynamic exchange mechanism and provides an important guarantee for the long-term stable operation of lithium-sulfur batteries.

[0385] VII. Analysis of overall performance advantages:

[0386] Through systematic analysis of 20 embodiments and 3 comparative examples (a total of 23 experimental cases), the interface self-healing GPE technology proposed in this application has achieved significant technical breakthroughs in the following aspects:

[0387] 1. Polysulfide shuttle suppression: Compared with traditional GPE, the shuttle suppression rate is improved by 36.32%~46.4%, and the Li2S4 diffusion coefficient is reduced by 66.7%~82.4%, which fundamentally solves the core bottleneck problem of lithium-sulfur batteries.

[0388] 2. Improved interface stability: Interface impedance is reduced by 70%~82%, and self-healing efficiency is as high as 92%~98%, effectively solving the technical problem of unstable electrode / electrolyte interface.

[0389] 3. Improved electrochemical performance: Initial discharge capacity increased by 45.3%~55.8%, 300-cycle retention rate increased by 68.1%~85.4%, and rate performance increased by 36.4%~46.4%, achieving comprehensive optimization of electrochemical performance.

[0390] 4. Enhanced temperature adaptability: High temperature performance (60℃ retention rate) reaches 78%~88%, and low temperature performance (-20℃ capacity) reaches 68%~78%, significantly widening the operating temperature range.

[0391] 5. Optimized mechanical properties: Tensile strength is increased by 117%~145%, elongation at break is increased by 37.5%~51.8%, and adhesion strength is increased by 112%~156%, providing a reliable guarantee for long-term stable operation.

[0392] VIII. In terms of technological value and industrialization prospects:

[0393] This application combines innovative materials design with interface engineering technology to provide a systematic solution for simultaneously addressing the two core challenges of polysulfide shuttling and interface stability in lithium-sulfur batteries. Experimental results show that this technical solution not only exhibits excellent performance under laboratory conditions, but more importantly, it is simple to process, cost-effective, and has promising prospects for industrialization.

[0394] Industrialization advantages: The manufacturing process is compatible with existing battery production lines, and the increase in raw material costs is limited. It is expected to significantly improve the commercial viability of lithium-sulfur batteries while maintaining cost competitiveness. With the rapid development of the new energy vehicle and energy storage markets, this invention is expected to provide key technological support for the industrial application of high-energy-density lithium-sulfur batteries.

[0395] Table 9-1 Specific performance parameters of secondary batteries obtained in various embodiments of this application (I)

[0396]

[0397] Table 9-2 Specific performance parameters of secondary batteries obtained in various embodiments of this application (II)

[0398]

[0399] Note: The specific performance parameter trends of Examples 19 and 20 are similar to those of Example 2, with the main difference being in the interface impedance-related indicators.

[0400] The verification objectives for each embodiment and comparative example in Tables 7-1, 7-2, 8-1, 8-2, 9-1, and 9-2 are as follows:

[0401] The objectives of Examples 1, 2 (and any comparative examples) remain unchanged, with Example 2 serving as the "overall baseline" for subsequent optimizations.

[0402] Parameter optimization group:

[0403] Examples 3-6: Cross-validation of UPy×SS cross-linking density (low / low; low / high; high / low; high / high).

[0404] Examples 7-9: Heat treatment temperature series (50℃; 70℃ [internal reference]; 90℃).

[0405] Examples 10-11 and 14: Liquid content series (60wt%, 85wt%, 80wt%).

[0406] Application validation groups (all based on baseline formulations):

[0407] Examples 12-13: Coating thickness (15μm; 25μm).

[0408] Example 15: High-rate performance (2C).

[0409] Example 16: Low temperature performance (-20℃).

[0410] Example 17: Polysulfide shuttle inhibition.

[0411] Example 18: Long-term stability (1000 cycles).

[0412] Example 19: Verification of GPE film coating on negative electrode.

[0413] Example 20: Verification by coating both positive and negative electrodes with GPE film.

[0414] Through systematic experimental verification, the interface self-healing GPE technology based on disulfide / hydrogen bond synergy proposed in this application successfully solves the core technical challenges faced by lithium-sulfur batteries. The synergistic dynamic network design not only effectively suppresses polysulfides but also significantly improves interface stability, thereby enhancing the practical application performance of lithium-sulfur batteries.

[0415] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes can be made in form and detail without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A method for preparing a secondary battery, characterized in that, include: A battery cell assembly is provided, wherein the battery cell assembly is formed by stacking or winding a positive electrode sheet, a separator and a negative electrode sheet; A housing is provided, the housing having a receiving chamber for placing the battery cell assembly within the receiving chamber; An initial electrolyte is provided and injected into the receiving chamber; Perform the formation step; The positive electrode and / or the negative electrode are coated with a gel polymer electrolyte membrane, which contains a triple dynamic network structure, including a polyurethane backbone hydrogen bond network, a uracil ketone supramolecular hydrogen bond network, and a disulfide dynamic covalent bond network. The method for preparing the gel polymer electrolyte membrane includes: The functionalized polyurethane polymer is dispersed in the initial electrolyte to obtain a precursor solution; After coating the precursor solution onto the surface of the positive electrode and / or the negative electrode, the gel polymer electrolyte membrane is formed on the surface of the positive electrode and / or the negative electrode by solvent evaporation and heat treatment. The functionalized polyurethane polymer includes a polyurethane backbone, as well as a disulfide-containing dynamic covalent side chain and a uracil-containing supramolecular recognition side chain grafted onto the polyurethane backbone. The preparation method of the functionalized polyurethane polymer includes: A polyurethane prepolymer was obtained by stepwise addition polymerization of a diisocyanate compound, a polyether diol, and an alkynyl diol. The polyurethane prepolymer, the compound containing uracil azido units, and the compound containing disulfide azido units are subjected to a click chemical reaction under the catalysis of a copper catalyst to obtain the functionalized polyurethane polymer.

2. The method for preparing a secondary battery according to claim 1, characterized in that, In the gel polymer electrolyte membrane, the polyurethane backbone constitutes the polyurethane backbone hydrogen bond network, the uracilone supramolecular recognition side chain constitutes the uracilone supramolecular hydrogen bond network, and the disulfide-containing dynamic covalent side chain constitutes the disulfide dynamic covalent bond network.

3. The method for preparing a secondary battery according to claim 1, characterized in that, The functionalized polyurethane polymer has a mass fraction of 10% to 50% in the precursor solution.

4. The method for preparing a secondary battery according to claim 1, characterized in that, The molar ratio of the diisocyanate compound to the total glycol component is (1.05~1.5):1; the molar percentage of the alkynyl diol in the total glycol component is 5%~30%; the number average molecular weight of the polyurethane prepolymer is 2000Da~8000Da; and the number average molecular weight of the polyether diol is 1000Da~5000Da. In the functionalized polyurethane polymer, the grafting rate of the uracil azido unit is 5%~40% of the total molar number of alkynyl sites, the grafting rate of the disulfide azido unit is 5%~30% of the total molar number of alkynyl sites, and the sum of the grafting rates of the uracil azido unit and the disulfide azido unit does not exceed 50% of the total molar number of alkynyl sites. The total glycol component is the collective term for the polyether diol and the alkynyl diol.

5. The method for preparing a secondary battery according to claim 4, characterized in that, The diisocyanate compound includes at least one of aliphatic diisocyanate or alicyclic diisocyanate; the polyether diol includes at least one of polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol, or PEG-PPG block copolymer diol; and the alkynyl-containing diol includes at least one of 2-butyn-1,4-diol, propynyl alcohol diol derivative, 3-butyn-1-ol diol derivative, 2,4-hexadiyn-1,6-diol, or 2,2-bis(propynoxymethyl)-1,3-propanediol.

6. The method for preparing a secondary battery according to claim 1, characterized in that, The method for preparing the compound containing the uracil azido unit includes: Reaction of 6-methylisocytosine or its derivatives with compounds containing isocyanate groups yields compounds containing uracil ketone structures; A linker arm that can be converted into an azide group is introduced onto the compound containing the uracil ketone structure; The end of the connecting arm is converted into an azide group to obtain the compound containing the uracil azido unit.

7. The method for preparing a secondary battery according to claim 1, characterized in that, The method for preparing the compound containing disulfide azide units includes: Oxidation of thiol-containing azide compounds to form disulfide bonds; or, Synthesize azide compounds containing disulfide bonds.

8. The method for preparing a secondary battery according to claim 1, characterized in that, The click chemical reaction is either a one-step reaction or a stepwise reaction.

9. The method for preparing a secondary battery according to claim 8, characterized in that, The click chemical reaction is a one-step reaction, specifically: The polyurethane prepolymer is dissolved in an organic solvent, and the compound containing uracil azido units and the compound containing disulfide azido units are added sequentially. The reaction is carried out at 15°C to 80°C to obtain the functionalized polyurethane polymer.

10. The method for preparing a secondary battery according to claim 8, characterized in that, The click chemical reaction is a stepwise reaction, specifically including: Premixing stage: The polyurethane prepolymer is dissolved in an organic solvent, and the compound containing uracil azido units and the compound containing disulfide azido units are added sequentially. Premixing is carried out at a first temperature to obtain a mixture. Reaction stage: The mixture is reacted at a second temperature; Post-processing stage: The product obtained in the reaction stage is post-processed at a third temperature to obtain the functionalized polyurethane polymer; The third temperature > the second temperature > the first temperature.

11. The method for preparing a secondary battery according to claim 10, characterized in that, The first temperature is 15℃~30℃, the second temperature is 35℃~55℃, and the third temperature is 50℃~80℃.

12. A secondary battery, characterized in that, The secondary battery is obtained by the preparation method according to any one of claims 1 to 11.

13. A battery device, characterized in that, The battery device includes multiple secondary batteries as described in claim 12, and the battery device includes one or more of battery modules, battery packs, and energy storage batteries.

14. An electrical appliance, characterized in that, The electrical device includes the battery device as described in claim 13, the battery device being used to provide electrical energy.

15. An energy storage device, characterized in that, The energy storage device includes the battery device as described in claim 13, the battery device being used to store electrical energy.

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