An inorganic solid electrolyte membrane positive electrode and energy storage battery

Abstract

This invention discloses a method for preparing an inorganic solid electrolyte membrane positive electrode with an oxygen-containing free radical scavenger loaded, comprising the following steps: S1: mixing an inorganic solid electrolyte, a high molecular weight organic polymer, and a conjugated polyene oxygen-containing free radical scavenger in an organic solvent to obtain a spinning solution; S2: spraying the spinning solution obtained in S1 onto a current collector coated with a positive electrode active layer using electrospinning technology to obtain an inorganic solid electrolyte membrane positive electrode with an oxygen-containing free radical scavenger loaded; a three-dimensional ion transport channel is constructed, which effectively accelerates the lithium-ion conduction rate, delays the thermal runaway time of the lithium-ion battery, and reduces the severity of thermal runaway of the lithium-ion battery, thereby obtaining a positive electrode with good conductivity, good thermal stability, and high safety.

Description

Technical Field

[0001] This invention relates to the field of solid electrolyte membrane technology for lithium-ion batteries, specifically to an inorganic solid electrolyte membrane positive electrode and an energy storage battery. Background Technology

[0002] Lithium-ion batteries are widely used in electronic devices, electric vehicles, and energy storage systems due to their advantages such as portability, high energy density, and long cycle life. However, lithium-ion batteries, especially those using high-nickel cathode active materials such as ternary nickel-cobalt-manganese (NCM), are prone to thermal runaway under extreme operating conditions such as high temperatures, posing safety hazards and causing significant public concern. One of the main reasons for thermal runaway in lithium-ion batteries is that the structure of cathode active materials such as ternary nickel-cobalt-manganese (NCM) is unstable at high temperatures, making them prone to phase transitions. The release of reactive oxygen species (such as O2 and O3) during these phase transitions... - O2 2- The oxygen released from the positive electrode material reacts rapidly and violently with the organic electrolyte, accelerating the redox reaction between the positive electrode active material and the electrolyte, thus triggering thermal runaway in lithium-ion batteries. Therefore, there is an urgent need to develop a strategy to slow down the release of oxygen from the positive electrode active material at high temperatures and reduce the reaction rate between the positive electrode and the electrolyte.

[0003] Common strategies include elemental doping, surface modification (such as surface coating, flame retardant coating, or insulating material coating), and particle design. These methods can stabilize the cathode structure, increase the phase transition temperature of the material, reduce interfacial reactions, and thus delay the oxygen release process of the cathode active material, thereby improving the thermal stability of the material. However, the effects of these strategies are limited, and their effect on delaying oxygen release from the cathode active material is relatively weak. Since thermal runaway and failure of batteries under high-temperature environments involve complex cascade exothermic reactions, a single strategy cannot completely solve the above safety problems or simultaneously maintain and improve electrochemical performance.

[0004] Therefore, it is necessary to develop a new electrolyte system that can efficiently bind oxygen in the cathode material, significantly delay oxygen release, and effectively suppress adverse reactions between oxygen and the electrolyte while ensuring good electrochemical performance. This will comprehensively improve the thermal stability and safety performance of lithium-ion batteries while ensuring good electrochemical performance. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by disclosing a method for preparing a high-safety solid electrolyte membrane positive electrode with a loaded conjugated polyene oxygen-containing free radical scavenger. This positive electrode, by loading a solid electrolyte membrane containing a conjugated polyene oxygen-containing free radical scavenger, effectively captures and inhibits the release of reactive oxygen species in the positive electrode material, while providing an additional ion conduction pathway for the solid electrolyte in the positive electrode and contributing to stable lithium-ion deposition. This lays a solid foundation for achieving excellent electrochemical performance in lithium-ion batteries. Furthermore, the positive electrode using a solid electrolyte loaded with a conjugated polyene oxygen-containing free radical scavenger possesses non-flammable properties, providing a strong guarantee for the high safety of lithium-ion batteries. This invention also utilizes electrospinning technology to spray a solid electrolyte containing conjugated polyene oxygen-containing free radical scavengers onto the surface of the positive electrode sheet as a surface coating for the positive electrode sheet and applies it to lithium-ion batteries. This overcomes the problems of uneven distribution and particle aggregation of conjugated polyene oxygen-containing free radical scavengers in the electrolyte, increased material brittleness and easy structural damage caused by direct coating, and easy degradation of conjugated polyene oxygen-containing free radical scavengers under sensitive conditions such as heat or light when directly exposed to the surface of the positive electrode material. Thus, it constructs a three-dimensional ion transport channel with controllable particle size and stable structure of conjugated polyene oxygen-containing free radical scavengers in nanospun fibers, effectively accelerating the lithium-ion conduction rate and delaying the thermal runaway time of lithium-ion batteries, reducing the severity of thermal runaway in lithium-ion batteries, and obtaining a positive electrode sheet with good conductivity, good thermal stability and high safety, which is then applied to lithium-ion batteries.

[0006] This invention is achieved through the following technical solution:

[0007] This invention provides a method for preparing an inorganic solid electrolyte membrane positive electrode sheet loaded with an oxygen-containing free radical scavenger, comprising the following steps:

[0008] S1: An inorganic solid electrolyte, a high molecular weight organic polymer, and a conjugated polyene oxygen-containing free radical scavenger are mixed in an organic solvent to obtain a spinning solution;

[0009] S2: The spinning solution obtained in S1 is sprayed onto a current collector coated with a positive electrode active layer by electrospinning technology to obtain an inorganic solid electrolyte membrane positive electrode plate loaded with an oxygen free radical scavenger.

[0010] This invention addresses the thermal runaway problem in lithium-ion batteries during use, particularly under specific operating conditions such as high temperatures and the use of high-nickel cathode active materials. It also addresses the shortcomings of existing technologies in capturing reactive oxygen species in cathode materials and simultaneously achieving good conductivity and thermal runaway suppression. The invention provides a method for preparing an inorganic solid electrolyte membrane cathode sheet loaded with an oxygen-containing free radical scavenger. It innovatively employs conjugated polyene compounds as the oxygen-containing free radical scavenger in the cathode sheet. The conjugated polyene structure can capture peroxide radicals, hydroxyl radicals, and quench singlet oxygen, among other reactive oxygen species. Furthermore, this invention utilizes electrospinning technology to overcome the difficulties in achieving uniform distribution of conjugated polyene compounds as oxygen-containing free radical scavengers within the inorganic solid electrolyte, as well as their susceptibility to degradation under sensitive conditions such as direct exposure to light and high temperatures. This prevents the formation of a uniformly distributed, appropriately sized, and complete fiber network of oxygen-containing free radical scavengers. Simultaneously, it ensures the effective confinement of reactive oxygen species and improves ion transport. Electrospinning technology can form a flexible, interwoven nanofiber network structure, uniformly embedding conjugated polyene oxygen-containing free radical scavengers within the nanofiber network. This creates embedded three-dimensional beads on the nanofibers, preventing degradation of the conjugated polyene oxygen-containing free radical scavengers under light and heat-sensitive conditions, thus significantly improving their utilization rate. In a low-oxygen release environment at the positive electrode, it can capture oxygen free radicals; in a high-oxygen environment, it can rapidly react with oxygen to form hydrocarbons, hindering the transfer of oxygen from the positive electrode to the negative electrode, reducing crosstalk reactions, and improving safety. Simultaneously, it shortens the lithium-ion transport path in the positive electrode, resulting in more thorough electrolyte wetting. This solves the problems of brittle coating materials, uneven coating, easy degradation of oxygen free radical scavengers at high temperatures, hindered lithium-ion diffusion, and unstable interfaces in traditional coated electrodes. This invention improves the electrochemical performance of the battery while ensuring unobstructed ion transport paths and diffusion in the positive electrode. At the same time, the rapid and large-scale release of oxygen is significantly suppressed by the capture effect of conjugated polyene oxygen-containing free radical scavengers, effectively accelerating the lithium-ion conduction rate, delaying the thermal runaway time of the lithium-ion battery, and reducing the severity of thermal runaway in the lithium-ion battery.

[0011] As a further embodiment, the diameter of the spinning fibers in the positive electrode of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger is 350–450 nm, the porosity of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger is 40–70%, and the thickness of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger is 10–40 μm; the mass ratio of the conjugated polyene oxygen-containing free radical scavenger to the high molecular weight organic polymer in the spinning solution of S1 is 1–3 wt%; and the particle size distribution of the conjugated polyene oxygen-containing free radical scavenger in the spinning solution of S1 is 50–300 nm.

[0012] This invention, by further limiting the diameter of the nanospun fibers in the positive electrode, the porosity of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger, and the thickness of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger, and simultaneously limiting the mass ratio of the conjugated polyene oxygen-containing free radical scavenger to the high-molecular organic polymer and the particle size of the conjugated polyene oxygen-containing free radical scavenger within a certain range, ensures that the active oxygen in the high-nickel positive electrode active materials such as nickel-cobalt-manganese ternary materials in the positive electrode is effectively bound, forming a good ion transport pathway. At the same time, under suitable concentrations and particle sizes of the conjugated polyene oxygen-containing free radical scavenger, the active oxygen in the high-nickel positive electrode active materials such as nickel-cobalt-manganese ternary materials is more effectively bound, forming a good ion transport pathway. The conjugated polyene oxygen-containing free radical scavenger exists uniformly in the form of three-dimensional beaded strands within the nanospun fibers. This allows the conjugated polyene oxygen-containing free radical scavenger to be well embedded within the nanospun fiber skeleton formed by the high-molecular organic polymer, reducing the degradation of the conjugated polyene oxygen-containing free radical scavenger caused by sensitive external conditions. At the same time, the rational optimization of the above parameters further establishes a good ion transport channel and electron path. This allows the nanofiber network structure composed of spun fibers to have high ion transport efficiency, high thermal stability and safety performance, while also possessing sufficient flexibility and toughness. This avoids structural damage to the positive electrode sheet caused by excessive brittleness during repeated lithium-ion intercalation and deintercalation, thereby extending the battery's service life.

[0013] As a further embodiment, the electrospinning process parameters in S2 are set as follows: the voltage applied to the spinning solution obtained in S1 is 10–20 kV, and the flow rate is 1–4 mL / h. -1 Electrospinning is performed with the distance from the jet tip to the positive electrode plate being 15-35 cm, and the spinning time on one side is 1-3 hours.

[0014] This invention optimizes process parameters such as voltage, flow rate, and distance in electrospinning. This avoids the problems of excessively coarse fibers and low porosity caused by excessively large concentrations and particle sizes of conjugated polyene oxygen-containing free radical scavengers, coupled with excessively low voltage, excessively high flow rates, and excessively short distances between the spray tip and the positive electrode, which hinder ion transport. It also avoids the problems of excessively fine fibers caused by excessively high voltage, excessively slow flow rates, and excessively long distances between the spray tip and the positive electrode when the concentration and particle size of the conjugated polyene oxygen-containing free radical scavengers are too small. The decrease in mechanical strength of nanofibers, the increase in brittleness and the tendency to break, leads to poor continuity of the three-dimensional ion-conducting network structure and difficulty in forming a complete and dense film. It also avoids the problems of excessively large concentration and particle size of conjugated polyene oxygen-containing free radical scavengers, excessively high voltage and flow rate of spinning solution, excessively long distance from the spray tip to the positive electrode, resulting in excessively fine fibers and excessively high porosity. In such cases, the scavenger cannot be well encapsulated in the nanospun fibers, which would lead to the conjugated polyene oxygen-containing free radical scavenger being exposed on the material surface and easily degrading and failing.

[0015] The above-mentioned design of the present invention further enhances the battery's electrochemical performance while improving its thermal runaway suppression effect. It obtains a flexible nanofiber network structure with suitable thickness and suitable conductive network pores. The conjugated polyene oxygen free radical scavenger can be uniformly distributed inside the nanofibers, while the spinning fiber skeleton formed by the polymer also achieves good embedding of the conjugated polyene oxygen free radical scavenger. This results in a suitable spinning fiber diameter, suitable inorganic solid electrolyte membrane thickness and porosity in the positive electrode, and ultimately, a solid electrolyte membrane with excellent mechanical flexibility and toughness, high ionic conductivity and efficient oxygen scavenging ability is successfully constructed on the surface of the positive electrode.

[0016] As a further embodiment, the conjugated polyene oxygen-containing free radical scavenger includes a conjugated polyene oxygen-containing free radical scavenger with a substituted or unsubstituted unsaturated ring at one or both ends. When the unsaturated ring is substituted, the substituent is selected from one or more of C1 to C4 alkyl, hydroxyl, ketone, carboxyl, amino, sulfonic acid, and phosphate groups.

[0017] As a further embodiment, the conjugated polyene oxygen-containing free radical scavenger with substituted or unsubstituted unsaturated rings at both ends includes one or more of β-carotene, α-carotene, astaxanthin, lutein, and canthaxanthin.

[0018] As a further embodiment, the conjugated polyene oxygen-containing free radical scavenger having a substituted or unsubstituted unsaturated ring at one end includes one or more of retinol, retinaldehyde, retinoic acid, retinyl acetate, and retinyl palmitate.

[0019] As a further preferred embodiment, the conjugated polyene oxygen-containing free radical scavenger is a conjugated polyene oxygen-containing free radical scavenger with substituted or unsubstituted unsaturated rings at both ends.

[0020] This invention further prefers conjugated polyene oxygen-containing free radical scavengers with substituted or unsubstituted unsaturated rings at both ends as the oxygen-containing free radical scavengers in this invention. They can maintain high antioxidant properties even in high-temperature environments, and their degradation rate under sensitive conditions such as high temperature is slower than that of conjugated polyene oxygen-containing free radical scavengers with substituted or unsubstituted unsaturated rings at one end. Traditional oxygen-containing free radical scavenger compounds, such as polymeric oxygen-containing free radical scavengers, decompose or deactivate rapidly at high temperatures, failing to meet the thermal safety requirements of high-nickel batteries. In addition, in the battery system, the decomposition products of conjugated polyene oxygen-containing free radical scavengers with substituted or unsubstituted unsaturated rings at both ends are hydrocarbons, which are harmless byproducts. Furthermore, the products can act as a carbon layer to hinder oxygen diffusion, resulting in better flame retardant effects. Moreover, their antioxidant behavior has a significant oxygen partial pressure dependence. They can efficiently capture oxygen free radicals under low oxygen pressure and can be converted into a pro-oxidation state under high oxygen pressure, thereby controlling the oxygen environment in the battery cell, while traditional antioxidants only have a unidirectional effect.

[0021] As a further preferred embodiment, the conjugated polyene oxygen-containing free radical scavenger is β-carotene.

[0022] As a further embodiment, the method for preparing the positive electrode of the inorganic solid electrolyte membrane loaded with an oxygen-containing free radical scavenger includes the following steps:

[0023] S1: Disperse the inorganic solid electrolyte and the high molecular weight organic polymer in an organic solvent, heat and stir, add a conjugated polyene oxygen-containing free radical scavenger to the resulting solution, and continue stirring to obtain a uniformly mixed spinning solution.

[0024] S2: The spinning solution obtained in S1 is sprayed on both sides of the current collector coated with the positive electrode active layer by electrospinning technology, and after drying, an inorganic solid electrolyte membrane positive electrode sheet loaded with oxygen free radical scavenger is obtained.

[0025] As a further option, the heating in S1 is carried out using an oil bath, the temperature of which is 75-85°C and the duration of which is 1.5-2.5 hours.

[0026] As a further option, the inorganic solid electrolyte in S1 is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and chloride solid electrolytes;

[0027] As a further preferred embodiment, the oxide solid electrolyte is exemplary selected from one or more of lithium aluminum titanium phosphate compound (LATP), lithium lanthanum zirconium oxide compound (LLZO), and lithium lanthanum titanium oxide compound (LLTO).

[0028] As a further preferred embodiment, the sulfide solid electrolyte is exemplary selected from Li2S-P2S5 and Li2S-M. xS y One of -P2S5, in which Li2S-M x S y In -P2S5, M is selected from one or more of silicon (Si), germanium (Ge), and tin (Sn).

[0029] As a further preferred embodiment, the chloride solid electrolyte is exemplary selected from one or more of lithium hexachloroindium (Li3InCl6) and lithium hexachlorozirconium (Li3ZrCl6).

[0030] As a further option, the high molecular weight organic polymer is selected from one or more of vinyl and / or acrylonitrile synthetic polymer homopolymers / copolymers.

[0031] As a further preferred embodiment, the high molecular weight organic polymer is exemplary selected from one or more of polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polystyrene (PS).

[0032] As a further option, the organic solvent is selected from one or more of haloalkanes and / or nitrogen-containing organic solvents.

[0033] As a further preferred embodiment, the organic solvent is exemplary selected from one or more of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), chloroform (CHCl3), and dichloromethane (CH2Cl2).

[0034] As a further embodiment, the mass ratio of the inorganic solid electrolyte to the high molecular weight organic polymer in S1 is 1-3 wt%, and the particle size distribution of the inorganic solid electrolyte in the spinning solution is 50-300 nm.

[0035] As a further preferred embodiment, S1 involves dispersing the inorganic solid electrolyte lithium aluminum titanium phosphate compound (LATP) and the high molecular weight organic polymer polyacrylonitrile (PAN) in the organic solvents N,N-dimethylformamide (DMF) and chloroform (CHCl3) (volume ratio 9:1), heating and stirring in an oil bath at 80°C for 2 hours, stirring at room temperature under oxygen-free and light-protected conditions, adding a conjugated polyene oxygen-containing free radical scavenger, and continuing stirring for 12–36 hours to obtain a uniformly mixed spinning solution.

[0036] As a further option, the drying process in S2 is as follows: first, place the container at a temperature of 30–60°C, a vacuum degree of less than 0.05 MPa, and a nitrogen flow rate of 0.5–1 L / min. -1 Dry for 2-4 hours, then transfer to a vacuum environment and stand for 12-36 hours to allow it to dry completely.

[0037] As a further option, the current collector in S2 is a metal foil with a thickness of 6 to 14 μm.

[0038] As a further preferred embodiment, the current collector in S2 is made of aluminum foil with a thickness of 6 to 14 μm.

[0039] As a further embodiment, the positive electrode active layer in S2 includes an active material, a conductive agent, and a binder.

[0040] As a further embodiment, the coating thickness of the positive electrode active layer in S2 is 160–180 μm, and the double-sided coating density is 400–560 g / m². 2 .

[0041] As a further option, the active material in S2 is a ternary lithium nickel cobalt manganese (LiNi) x Co y Mn z O2), where x+y+z=1.

[0042] As an example, the ternary nickel-cobalt-manganese lithium in S2 can be selected as LiNi. 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.15 Mn 0.05 At least one of O2.

[0043] As a further option, the conductive agent is selected from at least one of carbon nanotubes and conductive agent Super P.

[0044] As a further option, the adhesive is selected from polyvinylidene fluoride (PVDF).

[0045] As a further embodiment, the active material accounts for 92-98% of the total mass of the active material, conductive agent, and binder.

[0046] The present invention also provides a positive electrode prepared by a method for preparing an inorganic solid electrolyte membrane loaded with an oxygen free radical scavenger, the positive electrode comprising a current collector, a positive active layer, and an inorganic solid electrolyte membrane layer containing an oxygen free radical scavenger.

[0047] As a further embodiment, the inorganic solid electrolyte membrane loaded with oxygen-containing free radical scavengers in the positive electrode sheet has a nanofiber network structure, which is formed by overlapping nanofibers; the nanofibers are embedded with beads of conjugated polyene oxygen-containing free radical scavengers.

[0048] As a further preferred embodiment, the diameter of the beads is 250–500 nm.

[0049] The present invention also provides a lithium-ion battery, comprising a positive electrode prepared by a method for preparing the positive electrode sheet or the positive electrode sheet of the inorganic solid electrolyte membrane loaded with an oxygen free radical scavenger.

[0050] The features and beneficial effects of this invention are as follows:

[0051] Currently, liquid electrolytes are flammable and prone to leakage; furthermore, commonly used commercial separators are prone to shrinkage at high temperatures, posing significant safety hazards. Inorganic solid electrolytes are particularly important in battery applications. This invention innovatively employs a polyene-based oxygen-containing free radical scavenger combined with electrospinning technology. By combining the highly efficient capture of reactive oxygen species by the polyene-based oxygen-containing free radical scavenger with electrospinning technology, a flexible three-dimensional nanofiber network is constructed. The oxygen-containing free radical scavenger is encapsulated within the fibers, preventing its degradation at high temperatures. This results in a positive electrode sheet of an inorganic solid electrolyte membrane loaded with oxygen-containing free radical scavengers that possesses both high ion conductivity and effectively suppresses thermal runaway, yielding a positive electrode material with high safety, long lifespan, high temperature resistance, and high energy density. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 The positive electrode sheet is the spun fiber loaded with LATP and β-carotene prepared in Example 1.

[0054] Figure 2 Scanning electron fiber optic image of the positive electrode of the inorganic solid electrolyte membrane loaded with oxygen-containing free radical scavenger prepared in Example 1. Detailed Implementation

[0055] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be given below, and embodiments of the present invention will be provided, but this does not limit the scope of the present invention.

[0056] This invention addresses the problems existing in the prior art by disclosing a method for preparing a high-safety solid electrolyte membrane positive electrode with a loaded conjugated polyene oxygen-containing free radical scavenger. This positive electrode, by loading a solid electrolyte membrane containing a conjugated polyene oxygen-containing free radical scavenger, effectively captures and inhibits the release of reactive oxygen species in the positive electrode material, while providing an additional ion conduction pathway for the solid electrolyte in the positive electrode and contributing to stable lithium-ion deposition. This lays a solid foundation for achieving excellent electrochemical performance in lithium-ion batteries. Furthermore, the positive electrode using a solid electrolyte loaded with a conjugated polyene oxygen-containing free radical scavenger possesses non-flammable properties, providing a strong guarantee for the high safety of lithium-ion batteries. This invention also utilizes electrospinning technology to spray a solid electrolyte containing conjugated polyene oxygen-containing free radical scavengers onto the surface of the positive electrode sheet as a surface coating for the positive electrode sheet and applies it to lithium-ion batteries. This overcomes the problems of uneven distribution and particle aggregation of conjugated polyene oxygen-containing free radical scavengers in the electrolyte, increased material brittleness and easy structural damage caused by direct coating, and easy degradation of conjugated polyene oxygen-containing free radical scavengers under sensitive conditions such as heat or light when directly exposed to the surface of the positive electrode material. Thus, it constructs a three-dimensional ion transport channel with controllable particle size and stable structure of conjugated polyene oxygen-containing free radical scavengers in nanospun fibers, effectively accelerating the lithium-ion conduction rate and delaying the thermal runaway time of lithium-ion batteries, reducing the severity of thermal runaway in lithium-ion batteries, and obtaining a positive electrode sheet with good conductivity, good thermal stability and high safety, which is then applied to lithium-ion batteries.

[0057] This invention provides a method for preparing an inorganic solid electrolyte membrane positive electrode sheet loaded with an oxygen-containing free radical scavenger, comprising the following steps:

[0058] S1: An inorganic solid electrolyte, a high molecular weight organic polymer, and a conjugated polyene oxygen-containing free radical scavenger are mixed in an organic solvent to obtain a spinning solution;

[0059] S2: The spinning solution obtained in S1 is sprayed onto a current collector coated with a positive electrode active layer by electrospinning technology to obtain an inorganic solid electrolyte membrane positive electrode plate loaded with an oxygen free radical scavenger.

[0060] This invention addresses the thermal runaway problem in lithium-ion batteries during use, particularly under specific operating conditions such as high temperatures and the use of high-nickel cathode active materials. It also addresses the shortcomings of existing technologies in capturing reactive oxygen species in cathode materials and simultaneously achieving good conductivity and thermal runaway suppression. The invention provides a method for preparing an inorganic solid electrolyte membrane cathode sheet loaded with an oxygen-containing free radical scavenger. It innovatively employs conjugated polyene compounds as the oxygen-containing free radical scavenger in the cathode sheet. The conjugated polyene structure can capture peroxide radicals, hydroxyl radicals, and quench singlet oxygen, among other reactive oxygen species. Furthermore, this invention utilizes electrospinning technology to overcome the difficulties in achieving uniform distribution of conjugated polyene compounds as oxygen-containing free radical scavengers within the inorganic solid electrolyte, as well as their susceptibility to degradation under sensitive conditions such as direct exposure to light and high temperatures. This prevents the formation of a uniformly distributed, appropriately sized, and complete fiber network of oxygen-containing free radical scavengers. Simultaneously, it ensures the effective confinement of reactive oxygen species and improves ion transport. Electrospinning technology can form a flexible, interwoven nanofiber network structure, uniformly embedding conjugated polyene oxygen-containing free radical scavengers within the nanofiber network. This creates embedded three-dimensional beads on the nanofibers, preventing degradation of the conjugated polyene oxygen-containing free radical scavengers under light and heat-sensitive conditions, thus significantly improving their utilization rate. In a low-oxygen release environment at the positive electrode, it can capture oxygen free radicals; in a high-oxygen environment, it can rapidly react with oxygen to form hydrocarbons, hindering the transfer of oxygen from the positive electrode to the negative electrode, reducing crosstalk reactions, and improving safety. Simultaneously, it shortens the lithium-ion transport path in the positive electrode, resulting in more thorough electrolyte wetting. This solves the problems of brittle coating materials, uneven coating, easy degradation of oxygen free radical scavengers at high temperatures, hindered lithium-ion diffusion, and unstable interfaces in traditional coated electrodes. This invention improves the electrochemical performance of the battery while ensuring unobstructed ion transport paths and diffusion in the positive electrode. At the same time, the rapid and large-scale release of oxygen is significantly suppressed by the capture effect of conjugated polyene oxygen-containing free radical scavengers, effectively accelerating the lithium-ion conduction rate, delaying the thermal runaway time of the lithium-ion battery, and reducing the severity of thermal runaway in the lithium-ion battery.

[0061] As a further embodiment, the diameter of the spinning fibers in the positive electrode of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger is 350–450 nm, the porosity of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger is 40–70%, and the thickness of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger is 10–40 μm; the mass ratio of the conjugated polyene oxygen-containing free radical scavenger to the high molecular weight organic polymer in the spinning solution of S1 is 1–3 wt%; and the particle size distribution of the conjugated polyene oxygen-containing free radical scavenger in the spinning solution of S1 is 50–300 nm.

[0062] This invention, by further limiting the diameter of the nanospun fibers in the positive electrode, the porosity of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger, and the thickness of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger, and simultaneously limiting the mass ratio of the conjugated polyene oxygen-containing free radical scavenger to the high-molecular organic polymer and the particle size of the conjugated polyene oxygen-containing free radical scavenger within a certain range, ensures that the active oxygen in the high-nickel positive electrode active materials such as nickel-cobalt-manganese ternary materials in the positive electrode is effectively bound, forming a good ion transport pathway. At the same time, under suitable concentrations and particle sizes of the conjugated polyene oxygen-containing free radical scavenger, the active oxygen in the high-nickel positive electrode active materials such as nickel-cobalt-manganese ternary materials is more effectively bound, forming a good ion transport pathway. The conjugated polyene oxygen-containing free radical scavenger exists uniformly in the form of three-dimensional beaded strands within the nanospun fibers. This allows the conjugated polyene oxygen-containing free radical scavenger to be well embedded within the nanospun fiber skeleton formed by the high-molecular organic polymer, reducing the degradation of the conjugated polyene oxygen-containing free radical scavenger caused by sensitive external conditions. At the same time, the rational optimization of the above parameters further establishes a good ion transport channel and electron path. This allows the nanofiber network structure composed of spun fibers to have high ion transport efficiency, high thermal stability and safety performance, while also possessing sufficient flexibility and toughness. This avoids structural damage to the positive electrode sheet caused by excessive brittleness during repeated lithium-ion intercalation and deintercalation, thereby extending the battery's service life.

[0063] As a further embodiment, the electrospinning process parameters in S2 are set as follows: the voltage applied to the spinning solution obtained in S1 is 10–20 kV, and the flow rate is 1–4 mL / h. -1 Electrospinning is performed with the distance from the jet tip to the positive electrode plate being 15-35 cm, and the spinning time on one side is 1-3 hours.

[0064] This invention optimizes process parameters such as voltage, flow rate, and distance in electrospinning. This avoids the problems of excessively coarse fibers and low porosity leading to hindered ion transport caused by excessively large concentrations and particle sizes of conjugated polyene oxygen-containing free radical scavengers, coupled with excessively low voltage in the spinning solution, excessively high flow rates, and excessively short distances between the spray tip and the positive electrode. Conversely, it avoids the problems of excessively fine fibers resulting from excessively low concentrations and particle sizes of conjugated polyene oxygen-containing free radical scavengers, coupled with excessively high voltage in the spinning solution, excessively slow flow rates, and excessively long distances between the spray tip and the positive electrode. The decrease in mechanical strength of nanofibers, the increase in brittleness and the tendency to break, leads to poor continuity of the three-dimensional ion-conducting network structure and difficulty in forming a complete and dense film. It also avoids the problems of excessively large concentration and particle size of conjugated polyene oxygen-containing free radical scavengers, excessively high voltage and flow rate of spinning solution, excessively long distance from the spray tip to the positive electrode, resulting in excessively fine fibers and excessively high porosity. In these cases, the scavengers cannot be well encapsulated in the nanospun fibers, which would lead to the conjugated polyene oxygen-containing free radical scavengers being exposed on the material surface and easily degrading and failing.

[0065] The above-mentioned design of the present invention further enhances the battery's electrochemical performance while improving its thermal runaway suppression effect. It obtains a flexible nanofiber network structure with suitable thickness and suitable conductive network pores. The conjugated polyene oxygen free radical scavenger can be uniformly distributed inside the nanofibers, while the spinning fiber skeleton formed by the polymer also achieves good embedding of the conjugated polyene oxygen free radical scavenger. This results in a suitable spinning fiber diameter, suitable inorganic solid electrolyte membrane thickness and porosity in the positive electrode, and ultimately, a solid electrolyte membrane with excellent mechanical flexibility and toughness, high ionic conductivity and efficient oxygen scavenging ability is successfully constructed on the surface of the positive electrode.

[0066] As a further example, the conjugated polyene oxygen-containing free radical scavenger includes a conjugated polyene oxygen-containing free radical scavenger with a substituted or unsubstituted unsaturated ring at one or both ends. When the unsaturated ring is substituted, the substituent is selected from one or more of C1 to C4 alkyl, hydroxyl, ketone, carboxyl, amino, sulfonic acid, and phosphate groups.

[0067] As a further example, the conjugated polyene oxygen-containing free radical scavenger with substituted or unsubstituted unsaturated rings at both ends includes one or more of β-carotene, α-carotene, astaxanthin, lutein, and canthaxanthin.

[0068] As a further example, the conjugated polyene oxygen-containing free radical scavenger having a substituted or unsubstituted unsaturated ring at one end includes one or more of retinol, retinaldehyde, retinoic acid, retinyl acetate, and retinyl palmitate.

[0069] As a further preferred example, the conjugated polyene oxygen-containing free radical scavenger is a conjugated polyene oxygen-containing free radical scavenger with substituted or unsubstituted unsaturated rings at both ends.

[0070] This invention further prefers conjugated polyene oxygen-containing free radical scavengers with substituted or unsubstituted unsaturated rings at both ends as the oxygen-containing free radical scavengers in this invention. They can maintain high antioxidant properties even in high-temperature environments, and their degradation rate under sensitive conditions such as high temperature is slower than that of conjugated polyene oxygen-containing free radical scavengers with substituted or unsubstituted unsaturated rings at one end. Traditional oxygen-containing free radical scavenger compounds, such as polymeric oxygen-containing free radical scavengers, decompose or deactivate rapidly at high temperatures, failing to meet the thermal safety requirements of high-nickel batteries. In addition, in the battery system, the decomposition products of conjugated polyene oxygen-containing free radical scavengers with substituted or unsubstituted unsaturated rings at both ends are hydrocarbons, which are harmless byproducts. Furthermore, the products can act as a carbon layer to hinder oxygen diffusion, resulting in better flame retardant effects. Moreover, their antioxidant behavior has a significant oxygen partial pressure dependence. They can efficiently capture oxygen free radicals under low oxygen pressure and can be converted into a pro-oxidation state under high oxygen pressure, thereby controlling the oxygen environment in the battery cell, while traditional antioxidants only have a unidirectional effect.

[0071] As a further preferred example, the conjugated polyene oxygen-containing free radical scavenger is β-carotene.

[0072] As a further example, the method for preparing the positive electrode of the inorganic solid electrolyte membrane loaded with an oxygen-containing free radical scavenger includes the following steps:

[0073] S1: Disperse the inorganic solid electrolyte and the high molecular weight organic polymer in an organic solvent, heat and stir, add a conjugated polyene oxygen-containing free radical scavenger to the resulting solution, and continue stirring to obtain a uniformly mixed spinning solution.

[0074] S2: The spinning solution obtained in S1 is sprayed on both sides of the current collector coated with the positive electrode active layer by electrospinning technology, and after drying, an inorganic solid electrolyte membrane positive electrode sheet loaded with oxygen free radical scavenger is obtained.

[0075] As a further example, the heating in S1 is performed using an oil bath, the temperature of which is 75-85°C and the duration of which is 1.5-2.5 hours.

[0076] As a further example, the inorganic solid electrolyte in S1 is selected from one or more of oxide solid electrolytes, sulfide solid electrolytes, and chloride solid electrolytes;

[0077] As a further preferred example, the oxide solid electrolyte is exemplary selected from one or more of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), and lithium lanthanum titanium oxide (LLTO).

[0078] As a further preferred example, the sulfide solid electrolyte is exemplary selected from Li2S-P2S5 and Li2S-M. xS y One of -P2S5, in which Li2S-M x S y In -P2S5, M is selected from one or more of silicon (Si), germanium (Ge), and tin (Sn).

[0079] As a further preferred example, the chloride solid electrolyte is exemplary selected from one or more of lithium hexachloroindium (Li3InCl6) and lithium hexachlorozirconate (Li3ZrCl6).

[0080] As a further option, the high molecular weight organic polymer is selected from one or more of vinyl and / or acrylonitrile synthetic polymer homopolymers / copolymers.

[0081] As a further example, the high molecular weight organic polymer is selected from one or more of polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polystyrene (PS);

[0082] As a further option, the organic solvent is selected from one or more of haloalkanes and / or nitrogen-containing organic solvents.

[0083] As a further example, the organic solvent is selected from one or more of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), chloroform (CHCl3), and dichloromethane (CH2Cl2).

[0084] As a further example, the mass ratio of the inorganic solid electrolyte to the high molecular weight organic polymer in S1 is 1 to 3 wt%, and the particle size distribution of the inorganic solid electrolyte in the spinning solution is 50 to 300 nm.

[0085] As a further preferred example, S1 involves dispersing the inorganic solid electrolyte lithium aluminum titanium phosphate compound (LATP) and the high molecular weight organic polymer polyacrylonitrile (PAN) in the organic solvents N,N-dimethylformamide (DMF) and chloroform (CHCl3) (volume ratio 9:1), heating and stirring in an oil bath at 80°C for 2 hours, stirring at room temperature under oxygen-free and light-protected conditions, adding a conjugated polyene oxygen-containing free radical scavenger, and continuing stirring for 12–36 hours to obtain a uniformly mixed spinning solution.

[0086] As a further example, the drying process in S2 is as follows: first, place the container at a temperature of 30–60°C, a vacuum degree of less than 0.05 MPa, and a nitrogen flow rate of 0.5–1 L / min. -1 Dry for 2-4 hours, then transfer to a vacuum environment and stand for 12-36 hours to allow it to dry completely.

[0087] As a further example, the current collector in S2 is a metal foil with a thickness of 6 to 14 μm.

[0088] As a further preferred example, the current collector in S2 is made of aluminum foil with a thickness of 6 to 14 μm.

[0089] As a further example, the positive electrode active layer in S2 includes an active material, a conductive agent, and a binder.

[0090] As a further example, the coating thickness of the positive electrode active layer in S2 is 160–180 μm, and the double-sided coating density is 400–560 g / m². 2 .

[0091] As a further example, the active material in S2 is a ternary lithium nickel cobalt manganese (LiNi) x Co y Mn z O2), where x+y+z=1.

[0092] As an example, the ternary nickel-cobalt-manganese lithium in S2 can be selected as LiNi. 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.8 Co 0.15 Mn 0.05 At least one of O2.

[0093] As a further example, the conductive agent is selected from at least one of carbon nanotubes and conductive agent Super P.

[0094] As a further example, the adhesive is selected from polyvinylidene fluoride (PVDF).

[0095] As a further example, the active material accounts for 92-98% of the total mass of the active material, conductive agent, and binder.

[0096] The present invention also provides a positive electrode prepared by a method for preparing an inorganic solid electrolyte membrane loaded with an oxygen free radical scavenger, the positive electrode comprising a current collector, a positive active layer, and an inorganic solid electrolyte membrane layer containing an oxygen free radical scavenger.

[0097] As a further example, the inorganic solid electrolyte membrane loaded with oxygen-containing free radical scavengers in the positive electrode has a nanofiber network structure, which is formed by overlapping nanofibers; the nanofibers are embedded with beads of conjugated polyene oxygen-containing free radical scavengers.

[0098] As a further preferred example, the diameter of the beads is 250–500 nm.

[0099] The present invention also provides a lithium-ion battery, comprising a positive electrode prepared by a method for preparing the positive electrode sheet or the positive electrode sheet of the inorganic solid electrolyte membrane loaded with an oxygen free radical scavenger.

[0100] As a specific example of the implementation of this invention, detailed cases are provided below:

[0101] Example 1:

[0102] Step 1: Preparation of the current collector coated with the positive electrode active layer:

[0103] Lithium nickel cobalt manganese oxide NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), conductive carbon nanotubes (CNTs), and binder PVDF were mixed in a mass ratio of 96:1.8:2.2, with N-methylpyrrolidone (NMP) as the solvent and 12μm aluminum foil as the current collector. A uniform positive electrode slurry was obtained by dry mixing under vacuum stirring. The slurry was then uniformly coated on both sides of the current collector surface using a transfer coating method. After drying during the coating process, the slurry was transferred to a vacuum oven at 110℃ for 24 hours for further drying. Finally, the electrode sheets were slit (30cm long and 16cm wide) and rolled.

[0104] Step 2: Preparation of spinning solution containing inorganic solid electrolyte:

[0105] 0.01 g of inorganic solid electrolyte LATP powder and 1 g of high molecular weight organic polymer polyacrylonitrile (PAN) were dispersed in 10 mL of organic solvent N,N-dimethylformamide (DMF) and chloroform (CHCl3) (volume ratio 9:1). The mixture was then heated and stirred in an oil bath at 80 °C for 2 h to obtain a uniformly mixed spinning solution of inorganic solid electrolyte.

[0106] Step 3: Preparation of spinning solution for inorganic solid electrolyte containing oxygen free radical scavenger:

[0107] The spinning solution was stirred at room temperature, and 0.01 g of β-carotene, an oxygen free radical scavenger, was added. The solution was then stirred for another 24 hours under anaerobic and light-protected conditions at room temperature to obtain a homogeneous spinning solution. The particle size distribution of the oxygen free radical scavenger in the spinning solution was 100–200 nm.

[0108] Step 4: Preparation of the inorganic solid electrolyte membrane positive electrode with oxygen free radical scavenger:

[0109] The spinning solution obtained in step 3 was transferred to a 10 mL disposable plastic syringe with a size 21 needle. The process parameters for electrospinning were set as follows: voltage 14 kV, flow rate 1.5 mL / h. -1 The distance between the needle and the receiving device is 20cm. Lay a ring of aluminum foil on the receiving device to facilitate the removal of the electrode after spinning and to prevent the electrode from being contaminated. Attach the electrode after rolling in step 1 to the receiving device with the aluminum foil, start the electrospinning instrument to begin spinning, and stop spinning on one side for 2 hours. Remove the electrode, lay the spinning surface flat with aluminum foil, and gently roll the spinning surface with a cylindrical hollow tube to make the spinning adhere better to the positive electrode. Spin the other side in the same way.

[0110] After spinning, the resulting film was vacuum dried at 45°C for 2 hours, and then left to stand in a vacuum environment for 12 hours. After drying the positive electrode, it was die-cut, and the remaining spun film at the tab was wiped clean with lint-free paper.

[0111] Step 5: Preparation of the negative electrode:

[0112] A mixture of silicon-carbon and artificial graphite was used as the active material, with a designed capacity of 600 mAh / g. The active material, conductive agent, binder, and thickener were mixed uniformly in a mass ratio of 93:2:4:1 to prepare the negative electrode slurry. Water was used as the solvent, and 6 μm copper foil was selected as the current collector. The negative electrode slurry was uniformly coated on both sides of the copper foil, and then dried, slit, rolled, and die-cut to obtain the negative electrode sheet.

[0113] Step 6: Cell Assembly:

[0114] The five negative electrode sheets obtained in step 5 and the four positive electrode sheets obtained in step 4 were sequentially stacked and packaged in a bag made of commercially available separator. The size of the bag was determined according to the size of the negative electrode. After hot pressing and welding of tabs, the bag was packaged in an aluminum-plastic film. The cell was then baked, injected with electrolyte (lithium salt: 1 mol / L LiPF6, solvent: ethylene carbonate, methyl ethyl carbonate mass ratio 3:7, additive: 10 wt% fluoroethylene carbonate), packaged, formed, and capacity tested to obtain a 1Ah cell. Subsequently, thermal safety tests were performed on the cell.

[0115] Example 2:

[0116] The difference between this embodiment and Embodiment 1 is that the single-sided spinning time in step 4 is 1 hour.

[0117] Example 3:

[0118] The difference between this embodiment and Embodiment 1 is that the single-sided spinning time in step 4 is 3 hours.

[0119] Example 4:

[0120] The difference between this embodiment and Embodiment 1 is that the amount of lithium aluminum titanium phosphate (LATP) added in step 2 is changed to 0.02g.

[0121] Example 5:

[0122] The difference between this embodiment and Embodiment 1 is that the amount of lithium aluminum titanium phosphate (LATP) added in step 2 is changed to 0.03g.

[0123] Example 6:

[0124] The difference between this embodiment and Embodiment 1 is that the amount of β-carotene added in step 3 is changed to 0.02g.

[0125] Example 7:

[0126] The difference between this embodiment and Embodiment 1 is that the amount of β-carotene added in step 3 is changed to 0.03g.

[0127] Example 8:

[0128] The difference between this embodiment and Embodiment 1 is that the process parameters for the electrospinning process are set as follows: voltage of 10kV and flow rate of 4mL / h. -1 The distance between the needle and the receiving device is 15cm.

[0129] Example 9:

[0130] The difference between this embodiment and Embodiment 1 is that the process parameters for the electrospinning process are set as follows: voltage of 20kV and flow rate of 1mL / h. -1 The distance between the needle and the receiving device is 35cm.

[0131] Example 10:

[0132] The difference between this embodiment and Example 1 is that the particle size distribution of the oxygen free radical scavenger in the spinning solution is 50-100 nm.

[0133] Example 11:

[0134] The difference between this embodiment and Embodiment 1 is that the particle size distribution of the oxygen free radical scavenger in the spinning solution is 200-300 nm.

[0135] Example 12:

[0136] The difference between this embodiment and Embodiment 1 is that the oxygen free radical scavenger is lycopene;

[0137] Example 13:

[0138] The difference between this embodiment and Embodiment 1 is that the oxygen free radical scavenger is retinol;

[0139] Comparative Example 1:

[0140] The difference between this embodiment and Embodiment 1 is that β-carotene was not added.

[0141] Comparative Example 2:

[0142] The difference between this embodiment and Embodiment 1 is that LATP was not added.

[0143] Comparative Example 3:

[0144] The difference between this embodiment and Example 1 is that LATP and β-carotene were not added.

[0145] Comparative Example 4:

[0146] The current collector and negative electrode coated with the positive electrode active layer obtained in step 1 of Example 1 are stacked using a commercial polypropylene (PP) separator. Then, the cells are installed in a shell, baked, injected with electrolyte (lithium salt: 1 mol / L LiPF6, solvent: ethylene carbonate and methyl ethyl carbonate in a mass ratio of 3:7, additive: 10 wt.% fluoroethylene carbonate), formed, and capacity tested to obtain a 1Ah battery cell.

[0147] Comparative Example 5:

[0148] The difference from Example 1 is that 1g of the high molecular weight organic polymer PAN was dispersed in 10mL of organic solvents N,N-dimethylformamide (DMF) and chloroform (CHCl3) (volume ratio 9:1), and heated and stirred in an oil bath at 80°C for 2h to obtain a homogeneous spinning solution. Then, 0.01g of oxygen free radical scavenger β-carotene was added, and the solution was stirred for 24h under oxygen-free and light-protected conditions at room temperature to obtain a homogeneous spinning solution. Finally, the spinning solution was coated on the positive electrode surface, and the layers were stacked and assembled into a pouch cell.

[0149] Comparative Example 6:

[0150] The difference from Example 1 is that the polyene oxygen-containing free radical scavenger β-carotene is replaced with tris(trimethylenesilyl)phosphite (TMSPI).

[0151] Comparative Example 7:

[0152] The difference from Example 1 is that in step 4, the spinning solution obtained in step 3 is transferred to a 10mL disposable plastic syringe, and a size 21 needle is used. The process parameters for electrospinning are set as follows: voltage 9.5kV, flow rate 4.5mLh. -1 The distance between the needle and the receiving device is 20cm.

[0153] Comparative Example 8:

[0154] The difference from Example 1 is that, under room temperature conditions, 0.05 g of the oxygen free radical scavenger β-carotene was added to the spinning solution obtained above, and the solution was stirred for 24 h under oxygen-free and light-protected conditions at room temperature to obtain a homogeneous spinning solution. The particle size distribution of the oxygen free radical scavenger in the spinning solution was 350–450 nm.

[0155] In step 4, the spinning solution obtained in step 3 is transferred to a 10mL disposable plastic syringe with a size 21 needle. The process parameters for electrospinning are set as follows: voltage 25kV, flow rate 4.5mL / h. -1 The distance between the needle and the receiving device is 40cm.

[0156] The fully charged positive electrode and electrolyte of some of the above embodiments and comparative examples were tested as follows:

[0157] (1) Differential scanning calorimetry-mass spectrometry (DSC-MS) test, the test scheme is as follows:

[0158] Step 1: Obtain a fully charged battery cell, charge it to 4.2V using a constant current and constant voltage of 0.33C, and cut off the current at 0.05C.

[0159] Step 2: The fully charged battery cell is placed in a glove box (with a water and oxygen content of less than 0.1 ppm) for disassembly to obtain a fully charged positive electrode sheet. Subsequently, the fully charged positive electrode sheet is scraped to obtain positive electrode powder.

[0160] Step 3: Weigh 8-10 mg of positive electrode powder into an aluminum crucible, flatten it, and add 4 μL of electrolyte (the same proportion as the soft pack electrolyte).

[0161] Step 4: Perform DSC-MS testing on the sample from Step 3. The test temperature range is 35 to 350℃, and the temperature rise rate is 10℃ / min.

[0162] According to the formula The oxygen content was calculated to evaluate the ability of β-carotene to capture oxygen released from the cathode material. Here, I represents the ion current intensity of oxygen (m / z = 32), in A; T: temperature, in °C; and m: mass of the cathode powder, in g.

[0163] The experimental results are shown in Table 1.

[0164] (2) Observation of shrinkage of inorganic solid electrolyte membrane of oxygen free radical scavenger: The inorganic solid electrolyte membrane of oxygen free radical scavenger was laid flat on the surface of the fixture and placed at 200℃ for 30 min to observe the shrinkage state. The experimental results are shown in Table 2.

[0165] (3) Battery cycle impedance test: Electrochemical impedance spectroscopy was performed on the battery cell after 100 cycles, and the results were fitted using Zview software. The experimental results are shown in Table 3.

[0166] (4) The cells of the above scheme were subjected to thermal chamber testing. The thermal safety test scheme refers to GB38031(2020)8.1.5. The experimental results are shown in Table 4.

[0167] Step 1: Obtain a fully charged battery cell, charge it to 4.2V using a constant current and constant voltage of 0.33C, and cut off the current at 0.05C.

[0168] Step 2: Set the heating program to raise the temperature to 100℃, 120℃, 140℃, 150℃, 160℃, 170℃, 180℃ and 200℃ at a heating rate of 5±2℃ / min, and hold each temperature range for 30min.

[0169] Step 3: Place the fully charged battery cell in the center of the hot box and collect the surface temperature of the cell and the ambient temperature. If the cell catches fire or explodes during the test, stop the experiment immediately. Record the voltage and temperature changes of the tested battery cell, as well as the changes in the ambient temperature, throughout the entire process.

[0170] (5) Capacity retention rate of the cells from the above embodiments and comparative examples after 100 cycles at a current density of 0.5C and a voltage window of 2.5–4.2V. The experimental results are shown in Table 5.

[0171] Table 1

[0172]

[0173]

[0174] As shown in Table 1, adding β-carotene to the inorganic solid electrolyte membrane can increase the peak temperature of the cathode material and significantly reduce the total heat of the cathode material with increasing β-carotene dosage. The oxygen release in the cathode also shows a decreasing trend with increasing β-carotene dosage, indicating that β-carotene has a significant oxygen capture effect.

[0175] Table 2

[0176]

[0177]

[0178] As shown in Table 2, the commercially available PP membranes used in Comparative Examples 4 and 5 exhibited shrinkage. The inorganic solid electrolyte membrane positive electrode sheet of this invention, obtained by electrospinning and loaded with an oxygen-containing free radical scavenger, possesses certain thermal stability.

[0179] Table 3

[0180] Example 1 31.43 2.24 28.56 Example 2 41.60 3.89 38.78 Example 3 41.12 3.93 37.23 Example 4 32.78 2.37 33.67 Example 5 31.13 2.25 29.31 Example 6 31.15 2.78 29.35 Example 7 32.78 2.67 30.19 Example 8 38.54 3.56 39.64 Example 9 39.86 3.64 39.58 Example 10 39.58 3.12 39.26 Example 11 39.64 3.15 37.25 Example 12 38.62 3.14 38.24 Example 13 36.35 2.99 35.89 Comparative Example 1 45.78 4.67 40.67 Comparative Example 2 45.90 4.83 40.89 Comparative Example 3 43.73 4.78 41.92 Comparative Example 4 49.83 4.99 43.54 Comparative Example 6 44.16 3.99 42.97

[0181] Table 4

[0182] Example 1 150 170 353 128 No fire Example 2 150 160 482 1208 No fire Example 3 150 170 378 107 No fire Example 4 150 160 567 430 No fire Example 5 150 160 582 346 No fire Example 6 150 170 382 709 No fire Example 7 150 170 298 1428 No fire Example 8 150 160 456 788 No fire Example 9 150 160 464 687 No fire Example 10 150 160 476 869 No fire Example 11 150 160 488 689 No fire Example 12 150 160 498 452 No fire Example 13 150 160 476 569 No fire Comparative Example 1 150 150 682 420 No fire Comparative Example 2 150 150 594 373 No fire Comparative Example 3 150 150 679 219 No fire Comparative Example 4 140 140 1209 864 fire Comparative Example 6 150 160 598 765 No fire

[0183] In Table 4, T1 is the self-generated heat temperature, which is the temperature point where the battery surface temperature is higher than the ambient temperature.

[0184] In Table 4, T2 is the battery thermal runaway temperature, which is the temperature at which the battery surface temperature rises sharply. It is much higher than the ambient temperature, and the battery cell will catch fire or explode.

[0185] In Table 4, T3 represents the highest temperature of the battery cell, which is the highest temperature reached during the battery's thermal runaway process.

[0186] The heat preservation time in Table 4 is the heat preservation time at that temperature when the battery experiences thermal runaway.

[0187] As shown in Table 3, the addition of inorganic solid electrolyte can significantly reduce the R of the cell. SEI This solves the problems of SEI film breakage and lithium dendrite formation at the interface, thereby extending the cycle life of the battery. As shown in Table 4, the positive electrode sheets obtained by electrospinning can effectively increase the thermal runaway temperature of the cell, reduce the maximum thermal runaway temperature of the cell, and suppress battery fire.

[0188] Table 5 Cyclic capacity retention rates of Examples 1-13 and Comparative Examples 1-8

[0189] Example 1 95.8 Example 2 94.8 Example 3 94.5 Example 4 95.0 Example 5 95.6 Example 6 95.2 Example 7 95.5 Example 8 94.1 Example 9 93.2 Example 10 92.4 Example 11 93.2 Example 12 93.6 Example 13 94.1 Comparative Example 1 76.2 Comparative Example 2 85.1 Comparative Example 3 82.3 Comparative Example 4 81.8 Comparative Example 5 0.2 Comparative Example 6 85.2 Comparative Example 7 0.2 Comparative Example 8 4.3

[0190] Based on the comprehensive test results of tests 1-5, according to Figure 1The positive electrode of the solid electrolyte membrane with a nanofiber network structure loaded with LATP and β-carotene prepared by the method shown obtained the best experimental results. A comparison of Examples 1-13 and Comparative Examples 1-8 shows that when other non-conjugated polyene oxygen-containing free radical scavengers are used, or no oxygen-containing free radical scavengers are added, or no inorganic solid electrolyte is added, or electrospinning spraying technology is not used, the performance is inferior to the examples in many aspects, including thermal runaway temperature and electrochemical performance. Comparative Example 5 shows that without electrospinning spraying, the cell prepared in Comparative Example 5, under a current density of 0.5C, has a voltage window of 2.5-4.2V and almost zero capacity in the first charge cycle (2.5-4.2V). This indicates that the inorganic solid electrolyte layer structure prepared without electrospinning spraying technology may have undergone significant structural damage or severe degradation, making it unable to maintain normal battery operation.

[0191] Comparing Examples 1 and 2-3, as shown in Table 6, the longer the electrospinning time, the thicker the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger, and the lower the porosity. Comparing Examples 1 and 6-11, it can be seen that simultaneously limiting and optimizing the dosage and particle size of the conjugated polyene oxygen-containing free radical scavenger, as well as the voltage, flow rate, and distance of the electrospinning process, can further optimize the diameter of the electrospun fibers obtained in this invention, as well as the thickness and porosity of the formed inorganic solid electrolyte membrane. Therefore, by further simultaneously optimizing the parameters of the conjugated polyene oxygen-containing free radical scavenger and electrospinning, the thickness, fiber diameter, and porosity of the inorganic solid electrolyte membrane can be further adjusted, thereby achieving good oxygen scavenging while ensuring high conductivity.

[0192] Table 6

[0193]

[0194] As can be seen from the comparison between Examples 1 and Examples 4-7, by optimizing the amount of solid electrolyte added and the amount of conjugated polyene oxygen free radical scavenger, the conductivity and oxygen free radical scavenging ability can be further balanced, thereby obtaining a lithium-ion battery that takes into account both electrochemical performance and thermal runaway suppression.

[0195] A comparison of Examples 1, 6-11, and Comparative Examples 7-8 shows that when the concentration and particle size of the conjugated polyene oxygen-containing free radical scavenger are further optimized within a certain range, and the diameter of the spinning fibers in the positive electrode sheet of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger, as well as the porosity and thickness of the inorganic solid electrolyte membrane loaded with the oxygen-containing free radical scavenger, are limited within a certain range, it ensures that the active oxygen in the high-nickel positive electrode active materials such as nickel-cobalt-manganese ternary materials in the positive electrode sheet is effectively bound and a good ion transport path is formed. At the same time, under suitable conditions, the concentration and particle size of the conjugated polyene oxygen-containing free radical scavenger are optimized within a certain range. By adjusting the concentration and particle size of the oxygen free radical scavenger, a flexible nanofiber network structure with suitable thickness and conductive network pores was obtained. The conjugated polyene oxygen free radical scavenger can be uniformly distributed inside the nanospun fibers, while the spinning fiber skeleton formed by the polymer also achieves good embedding of the conjugated polyene oxygen free radical scavenger. As a result, a solid electrolyte membrane with excellent mechanical flexibility and toughness, high ionic conductivity and efficient oxygen scavenging ability was successfully constructed on the surface of the positive electrode. On this basis, better thermal runaway suppression effect and electrochemical performance were obtained.

[0196] Comparative Example 7 suffered from excessively low spinning voltage and excessively high flow rate, insufficient to form a Taylor cone and jet of spinning solution, making spinning difficult and resulting in an incomplete spun structure. Comparative Example 8, with its excessively high flow rate and long distance, caused the solvent to solidify due to excessive evaporation during the jetting process, further hindering spinning and resulting in a defective spun structure. Based on these limitations, Comparative Examples 7 and 8 were difficult to spin, leading to short circuits after subsequent assembly into battery cells. The initial charging capacity of the battery cell was almost zero, preventing complete cycling.

[0197] A comparison of Examples 1 and 8-9 shows that by further limiting the electrospinning process parameters and optimizing the connection voltage and flow rate of the spinning solution, as well as the distance between the jet tip and the positive electrode, a flexible nanofiber network structure with suitable thickness and conductive network pore size can be obtained in this invention. This avoids the problems of excessively thick fibers and low pore size caused by excessively low spinning solution voltage, excessively high flow rate, and excessively short distance between the jet tip and the positive electrode, which would hinder ion transport. It also avoids the problems of excessively thin fibers, decreased mechanical strength, increased brittleness, and easy breakage caused by excessively high spinning solution voltage, excessively slow flow rate, and excessively long distance between the jet tip and the positive electrode, which would lead to poor continuity of the three-dimensional ion-conducting network structure and difficulty in forming a complete and dense film. Through the above optimizations, a solid electrolyte membrane with excellent mechanical flexibility, high ion conductivity, and efficient oxygen capture capability was successfully constructed on the surface of the positive electrode. Compared with Examples 8-9, Example 1 achieved lower impedance and better cycle performance.

[0198] A comparison of Examples 1, 6-7, and 10-11 shows that this invention, by optimizing the concentration and particle size of the conjugated polyene oxygen-containing free radical scavenger within a certain range, ensures that the active oxygen in the nickel-cobalt-manganese ternary material of the positive electrode is effectively bound, while avoiding the problem of excessively coarse nanofibers formed after electrospinning, which could hinder ion conduction or even completely block ion transport channels. It also avoids the problem of insufficient oxygen free radical capture due to excessively low oxygen free radical scavenger concentration, leading to thermal runaway. Furthermore, it improves the battery's electrochemical performance while enhancing its thermal runaway suppression effect.

[0199] Comparing Examples 1 and 12, when the conjugated polyene oxygen-containing free radical scavenger of the present invention is preferably a conjugated polyene oxygen-containing free radical scavenger with substituted or unsubstituted unsaturated rings at one or both ends, compared to lycopene which lacks an unsaturated ring structure, the unsaturated ring structure at the molecular ends significantly enhances the stability of the conjugated system and more effectively maintains its antioxidant activity under high temperature and high oxygen pressure environments. Furthermore, this type of structure can further enhance its binding ability and reaction efficiency with reactive oxygen species by regulating molecular conformation and electron distribution, thereby achieving dynamic capture and conversion of oxygen free radicals over a wider range of temperature and oxygen concentration. Therefore, the preferred conjugated polyene scavenger with an unsaturated ring structure can more fully exert its antioxidant capacity and significantly improve the thermal safety performance and structural stability of the battery under extreme conditions.

[0200] A comparison of Examples 1 and 13 shows that when the conjugated polyene oxygen-containing free radical scavenger is further specified as a conjugated polyene oxygen-containing free radical scavenger with substituted or unsubstituted unsaturated rings at both ends, the unsaturated ring structure at both ends of the molecule forms a longer conjugated system and a more symmetrical electronic distribution. This structure exhibits higher thermal stability and antioxidant efficiency than the single-end structure. The double-end structure enhances the overall rigidity of the molecule, reduces conformational changes and degradation rates at high temperatures, captures reactive oxygen species more efficiently, and generates a dense hydrocarbon barrier layer under high oxygen partial pressure, thereby more effectively blocking oxygen diffusion and crosstalk reactions. Under extreme application conditions, it provides a better thermal safety barrier and more stable electrochemical performance for lithium-ion batteries.

[0201] The present invention also used high performance liquid chromatography (HPLC) to determine the content of β-carotene, and then evaluated the effect of nanofibers formed by electrospinning on delaying the thermal degradation of oxygen free radical scavengers.

[0202] Electrospun nanofiber samples containing β-carotene were used as the experimental group. β-carotene powder was simply physically mixed with blank nanofiber samples as control group 1, and β-carotene powder was used as control group 2. All three groups of samples were heated at different temperatures (90℃, 120℃, and 150℃, each for 30 min) in a vacuum drying oven (protected from light). The resulting samples were then dissolved in chloroform. The extracts were injected into an HPLC system (C18 reversed-phase column, mobile phase: methanol and acetonitrile (9:1 v / v), flow rate: 1.0 mL / min, detection wavelength: 450 nm, injection volume: 20 μL). The peak areas were recorded, and the β-carotene content in the heat-treated samples was calculated. The untreated samples were analyzed by HPLC as the initial content.

[0203] The retention rate of β-carotene was calculated using the formula: C / C0 * 100.

[0204] C0: Initial β-carotene content (μg / mL), C is the β-carotene content (μg / mL) when heated to different temperatures.

[0205]

[0206] As can be seen from the table above, encapsulating β-carotene in nanofibers using electrospinning technology can significantly reduce the thermal degradation rate of β-carotene.

[0207] Therefore, electrospinning technology can fully utilize the confinement effect of nanofibers to achieve ultra-high dispersibility and ultra-strong stability of oxygen scavengers. Simultaneously, it creatively integrates lithium-ion conduction, oxygen capture, and mechanical support functions into a single nanostructural unit, forming a "three-in-one" multifunctional composite film. Compared to traditional simple physical mixing methods, this offers revolutionary advantages in improving oxygen capture efficiency, preventing scavenger migration / dissolution, ensuring long-term stability, simplifying battery structure, and optimizing interfacial reaction kinetics. It provides a highly promising technological route for solving the oxygen release problem in high-energy-density lithium batteries (especially those using high-nickel, lithium-rich manganese-based, and other high-voltage cathode materials).

[0208] like Figure 2As shown, the inorganic solid electrolyte with oxygen-containing free radical scavengers loaded on the positive electrode sheet prepared in Example 1, as seen by scanning electron microscopy, exhibits a three-dimensional fiber network obtained after electrospinning. The nanofibers uniformly embed the oxygen-containing free radical scavengers, which reduces the degradation caused by light or heat due to oxygen free radicals exposed to the external surface. This also effectively disperses the oxygen-containing free radical scavengers, giving the inorganic solid electrolyte layer a certain degree of toughness and improving its mechanical strength. This avoids the structural damage caused by excessive brittleness during direct coating. Furthermore, the tough three-dimensional fiber network provides a good transport channel for ions while effectively capturing oxygen-containing free radicals, reducing adverse reactions between reactive oxygen species and the electrolyte, and significantly lowering the risk of thermal runaway in the battery.

[0209] In summary, liquid electrolytes are flammable and prone to leakage; furthermore, commonly used commercial separators shrink at high temperatures, posing significant safety hazards. Therefore, inorganic solid electrolytes are particularly important in battery applications due to their safety, long lifespan, high energy density, and lack of pollution. However, their brittleness limits their application. This solution utilizes electrospinning technology to obtain a solid electrolyte that is resistant to high temperatures, thus reducing the risk of battery fire and explosion. This invention addresses the problems existing in the prior art by providing a method for preparing a positive electrode of an inorganic solid electrolyte loaded with a conjugated polyene oxygen-containing free radical scavenger. It innovatively employs conjugated polyene compounds as the oxygen-containing free radical scavenger for the positive electrode, and preferably uses conjugated polyenes with substituted or unsubstituted unsaturated rings at both ends. These are antioxidants that primarily rely on the conjugated structure of the polyene chain to capture peroxide radicals, hydroxyl radicals, and quench singlet oxygen. Furthermore, electrospinning technology overcomes the problem of difficulty in forming a uniform structure when used as an oxygen-containing free radical scavenger, thus preventing it from fully realizing its advantages. Electrospinning can form a flexible, interwoven nanofiber network structure, reducing the transport path of lithium ions in the positive electrode, resulting in more thorough electrolyte wetting and solving the problems of hindered lithium ion diffusion and interface instability in traditional coated electrodes. By combining oxygen-containing free radical capture with electrospinning technology, the interfacial instability caused by direct mixing and coating on the surface of the positive electrode is addressed. On this basis, while ensuring unobstructed ion transport paths and diffusion in the positive electrode, the electrochemical performance of the battery is improved. At the same time, the rapid and large-scale release of oxygen is greatly reduced by the capturing effect of the oxygen-containing free radical scavenger, which effectively accelerates the lithium-ion conduction rate, delays the thermal runaway time of the lithium-ion battery, and reduces the severity of thermal runaway.

[0210] It should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an inorganic solid electrolyte membrane positive electrode sheet loaded with an oxygen-containing free radical scavenger, characterized in that, Includes the following steps: S1: An inorganic solid electrolyte, a high molecular weight organic polymer, and a conjugated polyene oxygen-containing free radical scavenger are mixed in an organic solvent to obtain a spinning solution; S2: The spinning solution obtained in S1 is sprayed onto a current collector coated with a positive electrode active layer by electrospinning technology to obtain an inorganic solid electrolyte membrane positive electrode plate loaded with an oxygen free radical scavenger. The diameter of the spinning fibers in the positive electrode of the inorganic solid electrolyte membrane loaded with oxygen-containing free radical scavengers is 350-450 nm; the porosity of the inorganic solid electrolyte membrane loaded with oxygen-containing free radical scavengers is 40-70%; and the thickness of the inorganic solid electrolyte membrane loaded with oxygen-containing free radical scavengers is 10-40 μm. The mass ratio of the conjugated polyene oxygen-containing free radical scavenger to the high molecular weight organic polymer in the spinning solution of S1 is 1-3 wt%. The particle size distribution of the conjugated polyene oxygen-containing free radical scavenger in the spinning solution of S1 is 50-300 nm. The conjugated polyene oxygen-containing free radical scavenger includes a conjugated polyene oxygen-containing free radical scavenger with substituted or unsubstituted unsaturated rings at both ends. When the unsaturated rings are substituted, the substituents are selected from one or more of C1-C4 alkyl, hydroxyl, ketone, carboxyl, amino, sulfonic acid, and phosphate groups.

2. The preparation method according to claim 1, characterized in that, The electrospinning process parameters in S2 are set as follows: the voltage of the spinning solution obtained in S1 is 10~20 KV, and the flow rate is 1~4 mL / h. -1 Electrospinning is performed with the distance from the jet tip to the positive electrode plate being 15~35 cm, and the spinning time on one side is 1~3 hours.

3. The preparation method according to claim 1, characterized in that, The conjugated polyene oxygen-containing free radical scavengers with substituted or unsubstituted unsaturated rings at both ends include one or more of β-carotene, α-carotene, astaxanthin, lutein, and canthaxanthin.

4. The preparation method according to claim 1, characterized in that, The high molecular weight organic polymer is selected from one or more of vinyl and / or acrylonitrile polymer homopolymers / copolymers; the organic solvent is selected from one or more of haloalkanes and / or nitrogen-containing organic solvents.

5. The preparation method according to claim 1, characterized in that, Includes the following steps: S1: Disperse the inorganic solid electrolyte and the high molecular weight organic polymer in an organic solvent, heat and stir, add a conjugated polyene oxygen-containing free radical scavenger to the resulting solution, and continue stirring to obtain a uniformly mixed spinning solution. S2: The spinning solution obtained in S1 is sprayed on both sides of the current collector coated with the positive electrode active layer by electrospinning technology, and after drying, an inorganic solid electrolyte membrane positive electrode sheet loaded with oxygen free radical scavenger is obtained.

6. The preparation method according to claim 5, characterized in that, In S1, heating is performed using an oil bath at a temperature of 75-85°C for 1.5-2.5 hours.

7. The preparation method according to claim 5, characterized in that, The mass ratio of inorganic solid electrolyte to high molecular weight organic polymer in S1 is 1~3wt%, and the particle size distribution of inorganic solid electrolyte in spinning solution is 50~300nm.

8. The preparation method according to claim 5, characterized in that, The drying process in S2 is as follows: first, place the container at a temperature of 30~60℃, a vacuum degree of less than 0.05 MPa, and a nitrogen flow rate of 0.5~1 L / min. -1 Dry for 2-4 hours, then transfer to a vacuum environment and let stand for 12-36 hours to allow it to dry completely.

9. The preparation method according to claim 5, characterized in that, The positive electrode active layer in S2 includes an active material, a conductive agent, and a binder.

10. The preparation method according to claim 5, characterized in that, The coating thickness of the positive electrode active layer in S2 is 160~180 μm, and the double-sided coating density is 400~560 g / m². 2 .

11. A positive electrode prepared by the method for preparing a positive electrode of an inorganic solid electrolyte membrane loaded with an oxygen-containing free radical scavenger as described in any one of claims 1 to 10, characterized in that, The positive electrode includes a current collector, a positive active layer, and an inorganic solid electrolyte membrane layer containing an oxygen free radical scavenger.

12. The positive electrode sheet according to claim 11, characterized in that, The inorganic solid electrolyte membrane loaded with oxygen-containing free radical scavengers in the positive electrode has a nanofiber network structure, which is formed by overlapping nanofibers; the nanofibers are embedded with beads of conjugated polyene oxygen-containing free radical scavengers.

13. The positive electrode sheet according to claim 12, characterized in that, The diameter of the beads is 250~500 nm.

14. A lithium-ion battery comprising the positive electrode sheet according to any one of claims 11 to 13.

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