High-energy quasi-solid-state lithium secondary battery based on selenium positive electrode, preparation method and application

Abstract

The application provides a high-energy quasi-solid-state lithium secondary battery based on a selenium positive electrode, a preparation method and application, and belongs to the technical field of new energy. The quasi-solid-state lithium secondary battery is composed of a selenium / carbon composite positive electrode, a lithium metal negative electrode and a gel polymer-based electrolyte formed by ultraviolet light curing polymerization of a lithium salt and an ester-based solvent. The positive electrode material is a selenium / carbon fiber composite material, the selenium is commercial selenium powder, and the selenium loading is 30-50 wt.%. The negative electrode is commercial lithium metal sheet. The polymer gel electrolyte is formed by polymerization of lithium difluoro(oxalato)borate and lithium hexafluorophosphate in an ester-based solvent after photoinitiator polymerization. The quasi-solid-state lithium secondary battery prepared by the application has high energy density based on redox energy storage. The selenium positive electrode material has good selenium solidification effect and high active material utilization rate. The polymer gel electrolyte can effectively inhibit the growth of lithium dendrites, reduce the safety hazards of the battery, and has high application potential and commercial value.

Description

Technical Field

[0001] This invention belongs to the field of new energy technology and relates to a method for preparing a high-energy quasi-solid-state lithium secondary battery based on a selenium cathode and its application. Background Technology

[0002] Lithium-ion batteries are widely used in computers, portable electronic products, and mobile communications. Compared to traditional zinc-nickel and iron-nickel batteries, lithium-ion batteries have advantages such as high energy density, long lifespan, high discharge voltage, low self-discharge, no memory effect, and low environmental pollution, making them an ideal energy storage device. However, with the rapid development of emerging fields such as electric vehicles and smart grids, the energy density of lithium-ion batteries based on traditional metal oxide cathodes (e.g., LiCoO2, LiMn2O4, LiFePO4, etc.) is too low to meet current demands. The emergence of new energy vehicles, in particular, places higher requirements on battery capacity, cycle life, and other performance characteristics. Therefore, seeking a new type of rechargeable battery system with high specific energy has become particularly important.

[0003] Selenium, as a novel high-capacity lithium battery cathode material, has a capacity of up to 675 mAh g / L. -1 It has a high theoretical specific capacity and a high conductivity (1×10⁻⁶). -5 S cm -1 A novel lithium-selenium battery, which matches a selenium cathode with a metallic lithium anode, has a capacity of 1155 Wh / kg. -1 Mass energy density and 2528Wh / L -1 The high volumetric energy density of lithium-selenium batteries is more than twice that of traditional lithium-ion battery systems. Therefore, lithium-selenium batteries hold great promise for portable electronic devices, hybrid vehicles, and renewable energy storage. However, selenium cathodes still suffer from problems during cycling, such as low utilization of active materials, polyselenide shuttle, and electrode volume expansion. These issues reduce battery cycle stability; the use of flammable organic electrolytes also poses serious safety risks. These problems severely restrict the practical application of lithium-selenium batteries. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a preparation scheme for a high-energy quasi-solid-state lithium secondary battery based on a selenium cathode and a polymer gel electrolyte.

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

[0006] A high-energy quasi-solid-state lithium secondary battery based on a selenium cathode is composed of a cathode material, a cathode material, and a polymer gel electrolyte.

[0007] The positive electrode material is a composite material of selenium and carbon fiber, wherein the selenium is commercial selenium powder with a selenium loading of 30–50 wt.%; the negative electrode is a commercial lithium metal sheet; and the polymer gel electrolyte is formed by dissolving lithium difluorooxalate borate and lithium hexafluorophosphate in an ester solvent and then polymerizing them with a photoinitiator.

[0008] A method for preparing a high-energy quasi-solid-state lithium secondary battery based on a selenium cathode includes the following steps:

[0009] The first step is to prepare the cathode material.

[0010] 1) Polyacrylonitrile, polymethyl methacrylate, acetylene black, and a transition metal salt are added to N,N-dimethylformamide and stirred to dissolve, forming a precursor solution; wherein the transition metal salt is at least one selected from cobalt acetate, cobalt nitrate, nickel acetate, and nickel nitrate, and the concentration of the polyacrylonitrile is 65–120 mg / mL. -1 The concentration of polymethyl methacrylate is 25–65 mg / mL. -1 The concentration of acetylene black is 10–30 mg / mL. -1 The concentration of transition metal salts is 10–20 mg / mL. -1 ;

[0011] 2) After spinning the precursor solution obtained in step 1) using an electrospinning machine, the resulting product is heat-treated in air, wherein the heat treatment temperature is 100–300℃ and the heat treatment time is 1–5h.

[0012] 3) The material obtained in step 2) is heat-treated in argon atmosphere. The heat treatment temperature is 500–800℃, and the treatment time is 1–3 hours, to obtain a transition metal-doped porous carbon fiber material.

[0013] 4) The carbon fiber material obtained in step 3) is mixed with selenium powder in a certain proportion and heated in an inert atmosphere to obtain a selenium / carbon composite material. The inert atmosphere is at least one of argon and nitrogen. The mass ratio of carbon fiber material to selenium powder is 4:6–6:4. The heating temperature is 260–380℃ and the heating time is 8–20h.

[0014] 5) The selenium / carbon composite material obtained in step 4) is mixed with carbon black conductive agent and polyvinylidene fluoride binder in a ratio of 8:1:1 to prepare a slurry, which is then coated onto a metal aluminum foil and dried to obtain a composite positive electrode. The selenium loading in the positive electrode material is 30–50 wt.%.

[0015] The second step is to prepare the polymer gel electrolyte.

[0016] Lithium difluorooxalate borate and lithium hexafluorophosphate were uniformly dissolved in an ester-based solvent under ambient temperature and pressure. After adding a photoinitiator, a polymer gel electrolyte was formed by ultraviolet irradiation. The ester-based solvent was at least one selected from polyethylene glycol diacrylate, fluoroethylene carbonate, diethyl carbonate, ethylene carbonate, and ethoxylated trimethylolpropane triacrylate. The concentration of lithium difluorooxalate borate was 28–144 mg / mL. -1 The concentration of lithium hexafluorophosphate is 76–152 mg / mL. -1 The photoinitiator is at least one of 1-hydroxycyclohexylphenyl ketone or 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the photoinitiator concentration is 10–20 mg / mL. -1 The duration of ultraviolet light exposure is 5–20 seconds.

[0017] Step 3: Battery assembly

[0018] The positive electrode obtained in the first step and a commercial lithium metal negative electrode are placed together in a glove box, and the polymer gel electrolyte obtained in the second step is placed between the positive electrode obtained in the first step and the commercial lithium metal negative electrode to form a battery. The amount of polymer gel electrolyte used is 10–30 μL per milligram of selenium.

[0019] An application of a high-energy quasi-solid-state lithium secondary battery based on a selenium cathode, applied to lithium selenium batteries.

[0020] Compared with existing technologies, this invention solves the application problems of lithium selenium batteries, and its beneficial effects are as follows:

[0021] (1) The novel lithium selenide battery constructed in this invention can improve the utilization rate of positive electrode active materials, enabling the lithium selenide battery to reach the theoretical specific capacity.

[0022] (2) The carbon fiber material prepared by the present invention has a rich mesoporous structure. Elemental selenium is uniformly loaded in the mesopores of the porous carbon fiber material, which effectively inhibits the side reaction between the active material and the electrolyte and alleviates the problem of electrode volume expansion.

[0023] (3) The polymer gel electrolyte used in this invention combines the safety advantages of solid electrolytes with the high ion transport capability of liquid electrolytes, which further improves battery safety while ensuring battery performance. Attached Figure Description

[0024] Figure 1 This is a scanning electron microscope image of the selenium / porous carbon fiber composite cathode material prepared in Example 1 of this invention;

[0025] Figure 2 This is a transmission electron microscope image of the selenium / porous carbon fiber composite cathode material prepared in Example 2 of this invention;

[0026] Figure 3 This is the XRD pattern of the selenium / porous carbon fiber composite cathode material prepared in Example 3 of this invention;

[0027] Figure 4 This is the capacity-voltage curve of the lithium selenide battery assembled in Embodiment 4 of the present invention;

[0028] Figure 5 The coulombic efficiency and cycle stability of the lithium selenide battery assembled in Example 5 of this invention are shown. Detailed Implementation

[0029] In view of the many shortcomings of the prior art, the inventors of this invention, through long-term research and extensive practice, have proposed the technical solution of this invention. The following will further explain and illustrate this technical solution, its implementation process, and its principles. However, it should be understood that within the scope of this invention, the above-mentioned technical features of this invention and the technical features specifically described below (exemplary embodiments) can be combined with each other to constitute new or preferred technical solutions.

[0030] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0031] Example 1

[0032] The first step is to prepare the cathode material.

[0033] 1) Polyacrylonitrile, polymethyl methacrylate, acetylene black, and nickel acetate were added to N,N-dimethylformamide and stirred to dissolve, forming a precursor solution; the concentration of the polyacrylonitrile was 120 mg / mL. -1 The concentration of polymethyl methacrylate is 65 mg / mL. -1 The concentration of acetylene black was 10 mg / mL. -1 The concentration of nickel acetate is 10 mg / mL. -1 ;

[0034] 2) After spinning the precursor solution obtained in step 1) using an electrospinning machine, the resulting product is heat-treated in air, wherein the heat treatment temperature is 280℃ and the heat treatment time is 4h.

[0035] 3) The material obtained in step 2) is heat-treated in argon atmosphere. The heat treatment temperature is 800℃, and the treatment time is 2 hours, to obtain a transition metal-doped porous carbon fiber material.

[0036] 4) The carbon fiber material obtained in step 3) is mixed with selenium powder in a certain proportion and heated in an inert atmosphere to obtain a selenium / carbon composite material. The inert atmosphere is argon, the mass ratio of carbon fiber material to selenium powder is 4:6, the heating temperature is 260℃, and the heating time is 20h.

[0037] 5) The selenium / carbon composite material obtained in step 4) is mixed with carbon black conductive agent and polyvinylidene fluoride binder in a ratio of 8:1:1 to prepare a slurry, which is then coated onto a metal aluminum foil and dried to obtain a composite positive electrode. The selenium loading in the positive electrode material is 50 wt.%.

[0038] The second step is to prepare the polymer gel electrolyte.

[0039] Lithium difluorooxalate borate and lithium hexafluorophosphate were uniformly dissolved in an ester-based solvent under ambient temperature and pressure. After adding a photoinitiator, a polymer gel electrolyte was formed by ultraviolet irradiation. The ester-based solvent was a mixed solution of diethyl carbonate, ethylene carbonate, and ethoxylated trimethylolpropane triacrylate, and the concentration of lithium difluorooxalate borate was 72 mg / mL. -1 The concentration of lithium hexafluorophosphate is 152 mg / mL. -1 The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the photoinitiator concentration is 10 mg / mL. -1 The ultraviolet light exposure time is 5 seconds.

[0040] Step 3: Battery assembly

[0041] The positive electrode obtained in the first step and a commercially available lithium metal negative electrode are placed together in a glove box, and the polymer gel electrolyte obtained in the second step is placed between the positive electrode obtained in the first step and the commercially available lithium metal negative electrode to form a battery. The amount of polymer gel electrolyte used is 10 μL per milligram of selenium.

[0042] Figure 1 The image shown is a scanning electron microscope image of the selenium / porous carbon fiber composite cathode material in this embodiment, which proves that the carbon fiber has multiple channels that allow active materials to enter.

[0043] Example 2

[0044] The first step is to prepare the cathode material.

[0045] 1) Polyacrylonitrile, polymethyl methacrylate, acetylene black, and cobalt nitrate were added to N,N-dimethylformamide and stirred to dissolve, forming a precursor solution; the concentration of the polyacrylonitrile was 100 mg / mL. -1 The concentration of polymethyl methacrylate is 30 mg / mL. -1 The concentration of acetylene black was 20 mg / mL. -1 The concentration of cobalt nitrate is 20 mg / mL. -1 ;

[0046] 2) After spinning the precursor solution obtained in step 1) using an electrospinning machine, the resulting product is heat-treated in air, wherein the heat treatment temperature is 300℃ and the heat treatment time is 2h.

[0047] 3) The material obtained in step 2) is heat-treated in argon atmosphere. The heat treatment temperature is 700℃, and the treatment time is 3 hours, to obtain a transition metal-doped porous carbon fiber material.

[0048] 4) The carbon fiber material obtained in step 3) is mixed with selenium powder in a certain proportion and heated in an inert atmosphere to obtain a selenium / carbon composite material. The inert atmosphere is nitrogen, the mass ratio of carbon fiber material to selenium powder is 5:5, the heating temperature is 380℃, and the heating time is 12h.

[0049] 5) The selenium / carbon composite material obtained in step 4) is mixed with carbon black conductive agent and polyvinylidene fluoride binder in a ratio of 8:1:1 to prepare a slurry, which is then coated onto a metal aluminum foil and dried to obtain a composite positive electrode. The selenium loading in the positive electrode material is 45 wt.%.

[0050] The second step is to prepare the polymer gel electrolyte.

[0051] Lithium difluorooxalate borate and lithium hexafluorophosphate were uniformly dissolved in an ester-based solvent under ambient temperature and pressure. After adding a photoinitiator, a polymer gel electrolyte was formed by ultraviolet irradiation. The ester-based solvent was a mixed solution of polyethylene glycol diacrylate, fluoroethylene carbonate, and diethyl carbonate, and the concentration of lithium difluorooxalate borate was 144 mg / mL. -1 The concentration of lithium hexafluorophosphate is 152 mg / mL. -1 The photoinitiator was 1-hydroxycyclohexylphenyl ketone, and the photoinitiator concentration was 12 mg / mL. -1 The ultraviolet light exposure time is 10 seconds.

[0052] Step 3: Battery assembly

[0053] The positive electrode obtained in the first step and a commercially available lithium metal negative electrode are placed together in a glove box, and the polymer gel electrolyte obtained in the second step is placed between the positive electrode obtained in the first step and the commercially available lithium metal negative electrode to form a battery. The amount of polymer gel electrolyte used is 15 μL per milligram of selenium.

[0054] Figure 2 The image shown is a transmission electron microscope image of the selenium / porous carbon fiber composite cathode material in this embodiment, which proves that after melting and diffusion, selenium enters the fiber channels.

[0055] Example 3

[0056] The first step is to prepare the cathode material.

[0057] 1) Polyacrylonitrile, polymethyl methacrylate, acetylene black, and cobalt acetate were added to N,N-dimethylformamide and stirred to dissolve, forming a precursor solution; the concentration of the polyacrylonitrile was 80 mg / mL. -1 The concentration of polymethyl methacrylate is 40 mg / mL. -1 The concentration of acetylene black was 30 mg / mL. -1 The concentration of cobalt acetate is 20 mg / mL. -1 ;

[0058] 2) After spinning the precursor solution obtained in step 1) using an electrospinning machine, the resulting product is heat-treated in air, wherein the heat treatment temperature is 100°C and the heat treatment time is 1 hour.

[0059] 3) The material obtained in step 2) is heat-treated in argon atmosphere. The heat treatment temperature is 500℃, and the treatment time is 1 hour, to obtain a transition metal-doped porous carbon fiber material.

[0060] 4) The carbon fiber material obtained in step 3) is mixed with selenium powder in a certain proportion and heated in an inert atmosphere to obtain a selenium / carbon composite material. The inert atmosphere is argon, the mass ratio of carbon fiber material to selenium powder is 5.5:4.5, the heating temperature is 280℃, and the heating time is 15h.

[0061] 5) The selenium / carbon composite material obtained in step 4) is mixed with carbon black conductive agent and polyvinylidene fluoride binder in a ratio of 8:1:1 to prepare a slurry, which is then coated onto a metal aluminum foil and dried to obtain a composite positive electrode. The selenium loading in the positive electrode material is 40 wt.%.

[0062] The second step is to prepare the polymer gel electrolyte.

[0063] Lithium difluorooxalate borate and lithium hexafluorophosphate were uniformly dissolved in an ester-based solvent under ambient temperature and pressure. After adding a photoinitiator, a polymer gel electrolyte was formed by ultraviolet irradiation. The ester-based solvent was a mixed solution of fluoroethylene carbonate, ethylene carbonate, and ethoxylated trimethylolpropane triacrylate, and the concentration of lithium difluorooxalate borate was 115 mg / mL. -1 The concentration of lithium hexafluorophosphate is 76 mg / mL. -1 The photoinitiator is 2-hydroxy-2-methyl-1-phenyl-1-propanone, and the photoinitiator concentration is 15 mg / mL. -1 The ultraviolet light exposure time is 15 seconds.

[0064] Step 3: Battery assembly

[0065] The positive electrode obtained in the first step and a commercially available lithium metal anode are placed together in a glove box, and the polymer gel electrolyte obtained in the second step is placed between the positive electrode obtained in the first step and the commercially available lithium metal anode to form a battery. The amount of polymer gel electrolyte used is 20 μL per milligram of selenium.

[0066] Figure 3 The image shows the XRD pattern of the selenium / porous carbon fiber composite cathode material prepared in this embodiment, proving that cobalt selenide was generated in situ.

[0067] Example 4

[0068] The first step is to prepare the cathode material.

[0069] 1) Polyacrylonitrile, polymethyl methacrylate, acetylene black, and cobalt acetate were added to N,N-dimethylformamide and stirred to dissolve, forming a precursor solution; the concentration of the polyacrylonitrile was 65 mg / mL. -1 The concentration of polymethyl methacrylate is 30 mg / mL. -1 The concentration of acetylene black was 20 mg / mL. -1 The concentration of cobalt acetate is 15 mg / mL. -1 ;

[0070] 2) After spinning the precursor solution obtained in step 1) using an electrospinning machine, the resulting product is heat-treated in air, wherein the heat treatment temperature is 240℃ and the heat treatment time is 3h.

[0071] 3) The material obtained in step 2) is heat-treated in argon atmosphere. The heat treatment temperature is 750℃, and the treatment time is 2 hours, to obtain a transition metal-doped porous carbon fiber material.

[0072] 4) The carbon fiber material obtained in step 3) is mixed with selenium powder in a certain proportion and heated in an inert atmosphere to obtain a selenium / carbon composite material. The inert atmosphere is nitrogen, the mass ratio of carbon fiber material to selenium powder is 6:4, the heating temperature is 300℃, and the heating time is 10h.

[0073] 5) The selenium / carbon composite material obtained in step 4) is mixed with carbon black conductive agent and polyvinylidene fluoride binder in a ratio of 8:1:1 to prepare a slurry, which is then coated onto a metal aluminum foil and dried to obtain a composite positive electrode. The selenium loading in the positive electrode material is 35 wt.%.

[0074] The second step is to prepare the polymer gel electrolyte.

[0075] Lithium difluorooxalate borate and lithium hexafluorophosphate were uniformly dissolved in an ester-based solvent under ambient temperature and pressure. After adding a photoinitiator, a polymer gel electrolyte was formed by ultraviolet irradiation. The ester-based solvent was a mixed solution of polyethylene glycol diacrylate, diethyl carbonate, and ethylene carbonate, and the concentration of lithium difluorooxalate borate was 72 mg / mL. -1 The concentration of lithium hexafluorophosphate is 76 mg / mL. -1 The photoinitiator is 1-hydroxycyclohexylphenyl ketone, and the photoinitiator concentration is 20 mg / mL. -1 The ultraviolet light exposure time is 20 seconds.

[0076] Step 3: Battery assembly

[0077] The positive electrode obtained in the first step and a commercially available lithium metal negative electrode are placed together in a glove box, and the polymer gel electrolyte obtained in the second step is placed between the positive electrode obtained in the first step and the commercially available lithium metal negative electrode to form a battery. The amount of polymer gel electrolyte used is 25 μL per milligram of selenium.

[0078] Figure 4 This is the capacity-voltage curve of the lithium selenide battery assembled in this embodiment. The battery can achieve a theoretical specific capacity of 675 mAh g during charging and discharging. -1 .

[0079] Example 5

[0080] The first step is to prepare the cathode material.

[0081] 1) Polyacrylonitrile, polymethyl methacrylate, acetylene black, and nickel nitrate were added to N,N-dimethylformamide and stirred to dissolve, forming a precursor solution; the concentration of the polyacrylonitrile was 100 mg / mL. -1 The concentration of polymethyl methacrylate is 25 mg / mL. -1 The concentration of acetylene black was 20 mg / mL. -1 The concentration of nickel nitrate is 15 mg / mL. -1 ;

[0082] 2) After spinning the precursor solution obtained in step 1) using an electrospinning machine, the resulting product is heat-treated in air, wherein the heat treatment temperature is 180°C and the heat treatment time is 5 hours.

[0083] 3) The material obtained in step 2) is heat-treated in argon atmosphere. The heat treatment temperature is 800℃, and the treatment time is 3 hours, to obtain a transition metal-doped porous carbon fiber material.

[0084] 4) The carbon fiber material obtained in step 3) is mixed with selenium powder in a certain proportion and heated in an inert atmosphere to obtain a selenium / carbon composite material. The inert atmosphere is nitrogen, the mass ratio of carbon fiber material to selenium powder is 6:4, the heating temperature is 350℃, and the heating time is 8h.

[0085] 5) The selenium / carbon composite material obtained in step 4) is mixed with carbon black conductive agent and polyvinylidene fluoride binder in a ratio of 8:1:1 to prepare a slurry, which is then coated onto a metal aluminum foil and dried to obtain a composite positive electrode. The selenium loading in the positive electrode material is 30 wt.%.

[0086] The second step is to prepare the polymer gel electrolyte.

[0087] Lithium difluorooxalate borate and lithium hexafluorophosphate were uniformly dissolved in an ester-based solvent under ambient temperature and pressure. After adding a photoinitiator, a polymer gel electrolyte was formed by ultraviolet irradiation. The ester-based solvent was a mixed solution of polyethylene glycol diacrylate, fluoroethylene carbonate, diethyl carbonate, and ethylene carbonate, and the concentration of lithium difluorooxalate borate was 28 mg / mL. -1 The concentration of lithium hexafluorophosphate is 122 mg / mL. -1 The photoinitiator is 1-hydroxycyclohexylphenyl ketone, and the photoinitiator concentration is 18 mg / mL. -1 The ultraviolet light exposure time is 8 seconds.

[0088] Step 3: Battery assembly

[0089] The positive electrode obtained in the first step and a commercially available lithium metal anode are placed together in a glove box, and the polymer gel electrolyte obtained in the second step is placed between the positive electrode obtained in the first step and the commercially available lithium metal anode to form a battery. The amount of polymer gel electrolyte used is 30 μL per milligram of selenium.

[0090] Figure 5 The coulombic efficiency and cycle stability of the lithium selenide battery assembled in this embodiment are shown. After 50 cycles, the capacity retention rate is higher than 94%, and the coulombic efficiency is close to 100%.

[0091] It should be understood that the above embodiments are merely illustrative of the technical concept and features of the present invention, intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the scope of protection of the present invention. Although specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A high-energy quasi-solid-state lithium secondary battery based on a selenium positive electrode, characterized by, The high-energy quasi-solid lithium secondary battery is composed of a positive electrode material, a negative electrode material and a polymer gel electrolyte; The positive electrode material is a selenium / carbon fiber composite material; and the negative electrode is a commercialized metal lithium sheet; First step, preparation of a positive electrode material 1) polyacrylonitrile, polymethyl methacrylate, acetylene black and transition metal salt are added into N,N-dimethylformamide, stirred and dissolved to form a precursor solution; 2) the precursor solution obtained in step 1) is spun by using an electrostatic spinning machine, and the obtained product is heat-treated in air; 3) the material obtained in step 2) is heat-treated in argon to obtain a transition metal doped porous carbon fiber material; 4) the carbon fiber material obtained in step 3) is mixed with selenium powder in a certain proportion, heated in an inert atmosphere to obtain a selenium / carbon composite material; 5) the selenium / carbon composite material obtained in step 4) is mixed with carbon black conductive agent and polyvinylidene fluoride to prepare a slurry, which is coated on a metal aluminum foil, dried to obtain a composite positive electrode; Second step, preparation of a polymer gel electrolyte Lithium difluoro(oxalato)borate and lithium hexafluorophosphate are uniformly dissolved in an ester-based solvent at room temperature and normal pressure, and a photoinitiator is added to form a polymer gel electrolyte after ultraviolet irradiation; wherein the concentration of the photoinitiator is 10-20 mg mL -1 ; Third step, battery assembly In a glove box, the polymer gel electrolyte obtained in the second step is placed between the positive electrode obtained in the first step and the commercialized metal lithium negative electrode to form a battery; wherein the amount of the polymer gel electrolyte is 10-30 μL per milligram of selenium. The ester-based solvent is at least one of polyethylene glycol diacrylate, fluoroethylene carbonate, diethyl carbonate, ethylene carbonate and ethoxylated trimethylolpropane triacrylate.

2. The high energy quasi-solid state lithium secondary battery based on selenium positive electrode according to claim 1, characterized in that, The selenium in the positive electrode material is commercialized selenium powder, and the selenium loading is 30-50 wt.%.

3. The high energy quasi-solid state lithium secondary battery based on selenium positive electrode according to claim 1, characterized in that, The polymer gel electrolyte is lithium difluoro(oxalato)borate and lithium hexafluorophosphate dissolved in an ester-based solvent, and then polymerized by a photoinitiator.

4. A method for producing a high-energy quasi-solid-state lithium secondary battery based on the selenium positive electrode according to any one of claims 1 to 3, characterized by, Comprising the following steps: First step, preparation of a positive electrode material 1) polyacrylonitrile, polymethyl methacrylate, acetylene black and transition metal salt are added into N,N-dimethylformamide, stirred and dissolved to form a precursor solution; 2) the precursor solution obtained in step 1) is spun by using an electrostatic spinning machine, and the obtained product is heat-treated in air; 3) the material obtained in step 2) is heat-treated in argon to obtain a transition metal doped porous carbon fiber material; 4) the carbon fiber material obtained in step 3) is mixed with selenium powder in a certain proportion, heated in an inert atmosphere to obtain a selenium / carbon composite material; 5) the selenium / carbon composite material obtained in step 4) is mixed with carbon black conductive agent and polyvinylidene fluoride to prepare a slurry, which is coated on a metal aluminum foil, dried to obtain a composite positive electrode; Second step, preparation of a polymer gel electrolyte Lithium difluoro(oxalato)borate and lithium hexafluorophosphate are uniformly dissolved in an ester-based solvent at room temperature and normal pressure, and a photoinitiator is added to form a polymer gel electrolyte after ultraviolet irradiation; wherein the concentration of the photoinitiator is 10-20 mg mL -1 ; Third step, battery assembly In a glove box, the polymer gel electrolyte obtained in the second step is placed between the positive electrode obtained in the first step and the commercialized metal lithium negative electrode to form a battery; wherein the amount of the polymer gel electrolyte is 10-30 μL per milligram of selenium.

5. The method of claim 4, wherein the method is characterized by: In the first step 1), the transition metal salt is at least one of cobalt acetate, cobalt nitrate, nickel acetate, and nickel nitrate; in the second step, the ester solvent is at least one of polyethylene glycol diacrylate, fluoroethylene carbonate, diethyl carbonate, ethylene carbonate, and ethoxylated trimethylolpropane triacrylate; and in the second step, the photoinitiator is at least one of 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenyl-1-propanone.

6. The method of claim 4, wherein the method is characterized by: The concentration of polyacrylonitrile in the first step 1) is 65 - 120 mg mL -1 The concentration of polymethyl methacrylate is 25 - 65 mg mL -1 The concentration of acetylene black is 10 - 30 mg mL -1 The concentration of transition metal salt is 10 - 20 mg mL -1 The concentration of lithium difluoro(oxalato)borate in the second step is 28 - 144 mg mL -1 The concentration of lithium hexafluorophosphate is 76 - 152 mg mL -1 .

7. The method of claim 4, wherein the method is characterized by: In the first step 2), the heat treatment temperature is 100-300°C, and the heat treatment time is 1-5 h; in the first step 3), the heat treatment temperature is 500-800°C, and the treatment time is 1-3 h; and in the first step 4), the heating temperature is 260-380°C, and the heating time is 8-20 h.

8. The method for preparing a high-energy quasi-solid-state lithium secondary battery based on a selenium cathode according to claim 4, characterized in that, In the first step 4), the mixing mass ratio of the carbon fiber material to selenium powder is 4:6-6:

4.

9. The method for preparing a high-energy quasi-solid-state lithium secondary battery based on a selenium cathode according to claim 4, characterized in that, In the second step, the ultraviolet light irradiation time is 5-20 seconds.

10. Use of a selenium-based positive electrode according to any one of claims 1 to 3 for a high-energy quasi-solid-state lithium secondary battery, characterized in that, The selenium-based positive electrode is applied to a high-energy quasi-solid lithium secondary battery.

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