A preparation method of a PEO-based solid-state lithium-sulfur battery without a negative electrode

Abstract

The present application belongs to the technical field of lithium-sulfur full solid electrolyte, and discloses a preparation method of a PEO-based solid-state lithium-sulfur battery without a negative electrode. Lithium iodide is in-situ coated on LLZTO, and the same is dissolved with Li2S6 and PEO in anhydrous acetonitrile to form a solid-state electrolyte; a sulfur positive electrode sheet is obtained by mixing carboxymethyl cellulose lithium / styrene-butadiene rubber adhesive with sulfur and ketchen black molten sulfur. The electrolyte and the positive electrode sheet prepared above can be assembled into a full solid-state lithium-sulfur battery without a negative electrode, thereby improving safety, reducing cost, increasing the energy density of the battery, inhibiting the dissolution of long-chain lithium polysulfide in the PEO-based full solid-state lithium-sulfur battery, increasing the utilization rate of active substances in the battery, improving the cycle life and stability of the battery, and realizing high sulfur loading of the PEO-based full solid-state lithium-sulfur battery.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte technology, specifically relating to a method for preparing a PEO-based solid lithium-sulfur battery without a negative electrode. Background Technology

[0002] Lithium-sulfur batteries are considered one of the most promising energy storage systems due to their high energy density, high theoretical specific capacity, low cost, and non-toxicity. Currently, solid-state lithium-sulfur batteries with polymer solid electrolytes (SSEs) have great development potential due to their high flexibility and reliable safety; the ability to suppress uncontrollable Li dendrites and the flammability of liquid electrolytes; and their good interfacial compatibility compared to inorganic solid electrolytes. Among them, polyethylene oxide (PEO)-based solid polymer electrolytes have advantages such as low cost, good mechanical stability, good electrode compatibility, and good film-forming ability. However, previous reports have shown that at operating temperatures, PEO cannot effectively block the shuttle of long-chain lithium polysulfides, which dissolve into the PEO-based electrolyte, leading to the loss of active materials in the battery. Furthermore, the inherent volume expansion and low ionic / electronic conductivity of lithium-sulfur batteries result in relatively low sulfur loading in PEO-based solid-state lithium-sulfur batteries.

[0003] This invention dissolves long-chain lithium polysulfides and iodine-coated LLZTO in PEO. The presence of LLZTO provides a transport pathway for lithium ions in the high-concentration electrolyte. Lithium iodide is generated in situ on the LLZTO, forming a tight and uniform coating layer. Iodine-coated LLZTO can further increase the ionic conductivity of the electrolyte by promoting the stripping and recovery of lithium ions, and can also make the lithium ion transport in the electrolyte more uniform and stable. The saturation of lithium polysulfides in the PEO electrolyte effectively prevents further dissolution of lithium polysulfides on the electrode. In addition, the high-concentration solid polymer electrolyte can also reduce the crystallinity of PEO. Lithium carboxymethyl cellulose / styrene-butadiene rubber is used as a water-soluble binder in the sulfur cathode, which can alleviate the volume expansion during charge and discharge, inhibit the aggregation of discharge products (insulating short-chain lithium polysulfides), and promote the conversion of short-chain lithium polysulfides. This electrolyte, matched with this cathode system, can cycle charge and discharge without a negative electrode, while avoiding the reaction between lithium polysulfides in the electrolyte and the lithium sheet, improving safety, reducing cost, increasing battery energy density, and realizing high sulfur loading in solid-state lithium-sulfur batteries. Summary of the Invention

[0004] This invention provides a method for preparing a negative electrode-free PEO-based solid-state lithium-sulfur battery. The method involves in-situ coating lithium iodide onto LLZTO, dissolving it with Li2S6 and PEO in anhydrous acetonitrile to form a solid electrolyte; using Ketjen black molten sulfur as the conductive active material, and a mixture of lithium carboxymethyl cellulose and styrene-butadiene rubber as the binder; dissolving the conductive active material and binder in water to form a slurry and coating film to obtain a three-dimensional conductive network electrode; finally, assembling the PEO solid electrolyte with matching electrodes to create a negative electrode-free lithium-sulfur battery for testing.

[0005] The objective of this invention is achieved through the following technical solutions:

[0006] A method for preparing a PEO-based solid-state lithium-sulfur battery without a negative electrode includes the following steps:

[0007] S1: Inorganic garnet-type ceramic powder was ball-milled and mixed with elemental iodine. The mixture was then heated in a high-pressure sealed reactor to uniformly deposit iodine onto the ceramic powder, yielding solid A. Solid A was reacted thoroughly with an inorganic lithium compound and hydrazine hydrate in a solvent. The mixture was then centrifuged, washed, and dried to collect solid B. The solid B was subjected to a first high-temperature dehydration under a protective atmosphere, followed by a second high-temperature dehydration in a vacuum oven to obtain lithium iodide-coated ceramic powder.

[0008] S2: In an argon-filled glove box, add the lithium iodide-coated ceramic powder, long-chain lithium polysulfide, and PEO prepared in S1 to the solvent, mix and stir, coat it on a glass plate and dry it to obtain the PEO-based solid electrolyte.

[0009] S3: Conductive carbon material and elemental sulfur are mixed and ground, and calcined under a protective atmosphere to obtain a sulfur-carbon composite cathode material. The sulfur-carbon composite material and binder are dissolved in a solvent and mixed to form a slurry. The uniformly mixed slurry is coated on conductive aluminum foil and dried to obtain a cathode sheet. The cathode sheet prepared above is cut into circular pieces with a diameter of 12 mm as the cathode of the battery. The PEO-based solid electrolyte prepared above is cut into circular pieces with a diameter of 16 mm as the separator and electrolyte of the battery. Copper foil is cut into 16 mm circular pieces as the anode of the battery. In a glove box filled with argon atmosphere and with water and oxygen content both below 0.01 ppm, the cathode is sealed and assembled into a CR2032 coin cell in the following order: cathode shell, cathode, solid electrolyte, anode, steel sheet, gasket, and anode shell.

[0010] Preferably, the inorganic ceramic powder in step S1 is at least one of lithium lanthanum zirconium gallium oxide (LLZGO), lithium lanthanum zirconium aluminum oxide (LLZAO), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium niobium oxide (LLZNO), lithium lanthanum zirconium scandium oxide (LLZSO), lithium lanthanum tin niobium oxide (LLSNO), lithium lanthanum tin tantalum oxide (LLSTO), and lithium lanthanum zirconium tantalum oxide (LLZTO); the mass ratio of elemental iodine to inorganic ceramic powder is 1:2-0.5.

[0011] Preferably, in step S1, the ball mill speed is 400-600 r / min, the ball milling time is 0.5-3 h, the oven heating temperature is 70-150℃, and the heating time is 4-16 h.

[0012] Preferably, the inorganic lithium compound in step S1 is at least one of lithium hydroxide, lithium sulfate, lithium carbonate, lithium amino, and lithium imino.

[0013] Preferably, in step S1, the mass ratio of solid A to the inorganic compound of lithium to hydrazine hydrate is 1:0.05-0.25:0.1-0.5.

[0014] Preferably, the solvent in step S1 is at least one of methanol, water, dimethyl sulfoxide, N,N-dimethylformamide, ethanol, diethyl ether, chloroform, acetone, and toluene; the mass ratio of solid A to solvent is 1:25-50.

[0015] Preferably, the protective gas in step S1 is at least one of helium, argon, nitrogen, and neon; the dehydration temperature is 90-120℃; and the dehydration time is 8-16 hours.

[0016] Preferably, the temperature of the second dehydration oven in step S1 is 180-220℃; the dehydration time is 12-20h.

[0017] Preferably, in step S2, the lithium polysulfide is at least one of Li2S4, Li2S5, Li2S6, Li2S7 and Li2S8; the mass ratio of PEO to lithium iodide-coated ceramic powder to lithium polysulfide is 5:1-5:0.1-1.

[0018] Preferably, in step S2, the organic solvent is at least one of anhydrous acetonitrile, anhydrous ethanol, anhydrous methanol, N,N-dimethylformamide, anhydrous acetone, and anhydrous propionitrile, and the mass ratio of PEO to the organic solvent is 1:8-16.

[0019] Preferably, the stirring temperature in step S2 is 40-80℃, and the stirring time is 10-15 hours.

[0020] Preferably, the thickness of the solid electrolyte membrane in step S2 is 40-60 μm.

[0021] Preferably, the conductive carbon material in step S3 is at least one of conductive carbon black, Ketjen black, acetylene black, conductive graphite, and carbon nanotubes.

[0022] Preferably, the mass ratio of conductive material to elemental sulfur in step S3 is 1:1-5.

[0023] Preferably, the protective atmosphere in step S3 is at least one of nitrogen, argon, neon, helium, hydrogen-argon, and oxygen; the calcination temperature is 130–170°C; and the calcination time is 8–16 h.

[0024] Preferably, the binder in step S3 is at least one of sodium carboxymethyl cellulose, polyvinylidene fluoride, polyethylene oxide, lithium carboxymethyl cellulose / styrene-butadiene rubber, sodium alginate, polyvinyl alcohol, polymethyl methacrylate, polytetrafluoroethylene, polyacrylic acid, polyacrylonitrile, and polyacrylate, and the mass ratio of the binder to the sulfur-carbon composite material is 1:7-11.

[0025] Preferably, in step S3, the solvent is at least one of N-methylpyrrolidone, water, dimethyl sulfoxide, N,N-dimethylformamide, ethanol, and acetone, and the mass ratio of the binder to the solvent is 1:100-300.

[0026] This invention involves in-situ coating of lithium iodide onto LLZTO, resulting in a tight bond between the lithium iodide and LLZTO. The presence of LLZTO provides a transport pathway for lithium ions in the high-concentration electrolyte. The lithium iodide coating layer can further increase the ionic conductivity of the electrolyte by promoting the stripping and recovery of lithium ions, and also allows for more uniform and stable transport of lithium ions within the electrolyte. Lithium iodide-coated LLZTO, Li₂S₆, and PEO are dissolved in anhydrous acetonitrile and dried to form a solid electrolyte. The saturation of lithium polysulfides in the PEO electrolyte effectively prevents further dissolution of lithium polysulfides on the electrode. Furthermore, the high-concentration solid polymer electrolyte can reduce the crystallinity of PEO. Lithium carboxymethyl cellulose / styrene-butadiene rubber is used as a water-soluble binder in the sulfur cathode, which can alleviate volume expansion during charge and discharge, inhibit the aggregation of discharge products (insulating short-chain lithium polysulfides), and promote the conversion of short-chain lithium polysulfides. This electrolyte, matched with this positive electrode system, allows for cyclic charging and discharging without a negative electrode. It also avoids the reaction between lithium polysulfides in the electrolyte and the lithium sheet, solving problems such as lithium polysulfide dissolution, low sulfur utilization, low sulfur loading, poor conductivity, and volume expansion in lithium-sulfur batteries. Furthermore, it improves safety, reduces cost, increases battery energy density, and achieves high sulfur loading in solid-state lithium-sulfur batteries. This invention presents a simple and large-scale synthesis modification method, providing valuable reference for the application of solid-state lithium-sulfur batteries. Attached Figure Description

[0027] Figure 1 The cyclic performance diagrams are for Examples 1-3 and Comparative Examples 1 and 2. Figure 2 The electrochemical impedance spectroscopy spectra of Examples 1-3, and Comparative Examples 1 and 2 are shown below. Figure 3 This is a cycle performance diagram of Example 1 with high-quality sulfur loaded; Detailed Implementation

[0028] Example 1

[0029] S1: 3g of LLZTO powder and 2g of elemental iodine were ball-milled at 500r / min for 1.5 hours and then heated at 120℃ for 10 hours in a high-pressure sealed reactor to uniformly deposit iodine onto ceramic powder, yielding solid A. 2g of solid A was reacted with 0.3g of lithium hydroxide and 0.6g of hydrazine hydrate in 70g of water, and the mixture was centrifuged, washed, and dried to collect solid B. Under argon protection, solid B underwent a first dehydration at 105℃ for 12 hours, followed by a second high-temperature dehydration at 200℃ for 16 hours in a vacuum oven to obtain LiI-coated LLZTO powder.

[0030] S2: 0.45g LiI coated with LLZTO powder, 0.75g PEO and 0.075g Li2S6 were dissolved in 9g anhydrous acetonitrile. The mixture was stirred at 60℃ for 12h, then allowed to stand to defoam. The defoamed solution was poured onto a polytetrafluoroethylene glass plate, coated evenly with a doctor blade, and dried to obtain a 50μm solid electrolyte membrane. It was then punched into discs for later use.

[0031] S3: Mix and grind 250mg Ketjen black and 750mg elemental sulfur, calcine at 155℃ for 12h to obtain a sulfur-carbon composite cathode material; dissolve 180mg of the sulfur-carbon composite material and 20mg of carboxymethyl cellulose lithium / styrene-butadiene rubber composite binder in 4g of water to make a slurry, coat the slurry on conductive aluminum foil, and dry to obtain a cathode sheet. Cut the prepared cathode sheet into a 12mm diameter circular sheet as the positive electrode of the battery, cut the prepared PEO-based solid electrolyte into a 16mm diameter circular sheet as the separator and electrolyte of the battery, and cut copper foil into a 16mm diameter circular sheet as the negative electrode of the battery. In a glove box filled with argon atmosphere and with water and oxygen content both below 0.01ppm, seal and assemble CR2032 type button batteries in the following order: cathode shell, positive electrode, solid electrolyte, negative electrode, steel sheet, gasket, and negative electrode shell.

[0032] After battery assembly, it was left to stand at 60℃ for 10 hours before charge-discharge testing. The discharge specific capacity after 100 cycles at a voltage of 1.7-2.8V and a current density of 0.5C was 1113.2 mAh g. -1 Meanwhile, electrochemical impedance spectroscopy revealed a battery resistance R of approximately 92 Ω. With a positive electrode containing 5 mg of high-quality sulfur, the discharge specific capacity after 100 cycles at a 0.5C current density was 661.0 mAh g. -1 .

[0033] Example 2

[0034] S1: 4g of LLZO powder and 2g of elemental iodine were ball-milled at 400r / min for 3 hours to mix. The mixture was then heated at 110℃ for 16 hours in a high-pressure sealed reactor to uniformly deposit iodine onto the ceramic powder, yielding solid A. 2g of solid A was reacted with 0.1g of lithium carbonate and 0.2g of hydrazine hydrate in 50g of acetone. The mixture was then centrifuged, washed, and dried to collect solid B. Under nitrogen protection, solid B underwent a first dehydration at 120℃ for 8 hours, followed by a second high-temperature dehydration at 200℃ for 16 hours in a vacuum oven to obtain LiI-coated LLZO powder.

[0035] S2: 0.15 g LiI-coated LLZO powder, 0.75 g PEO, and 0.075 g Li2S4 were dissolved in anhydrous acetonitrile. The mixture was stirred at 60°C for 12 hours and then allowed to stand to defoam. The defoamed solution was poured onto a polytetrafluoroethylene glass plate, coated evenly with a doctor blade, and dried to obtain a 60 μm solid electrolyte membrane. The membrane was then punched into discs for later use.

[0036] S3: Mix and grind 250mg Ketjen black and 750mg elemental sulfur, calcine at 155℃ for 12h to obtain a sulfur-carbon composite cathode material; dissolve 180mg of the sulfur-carbon composite material and 20mg of carboxymethyl cellulose lithium / styrene-butadiene rubber composite binder in 4g of water to make a slurry, coat the slurry on conductive aluminum foil, and dry to obtain a cathode sheet. Cut the prepared cathode sheet into a 12mm diameter circular sheet as the positive electrode of the battery, cut the prepared PEO-based solid electrolyte into a 16mm diameter circular sheet as the separator and electrolyte of the battery, and cut copper foil into a 16mm diameter circular sheet as the negative electrode of the battery. In a glove box filled with argon atmosphere and with water and oxygen content both below 0.01ppm, seal and assemble CR2032 type button batteries in the following order: cathode shell, positive electrode, solid electrolyte, negative electrode, steel sheet, gasket, and negative electrode shell.

[0037] After battery assembly, it was left to stand at 60℃ for 10 hours before charge-discharge testing. The discharge specific capacity after 100 cycles at a voltage of 1.7-2.8V and a current density of 0.5C was 1019.5 mAh g. -1 Meanwhile, electrochemical impedance spectroscopy revealed a battery resistance R of approximately 158 Ω. With a positive electrode containing 5 mg of high-quality sulfur, the discharge specific capacity after 100 cycles at a 0.5C current density was 673.7 mAh g⁻¹. -1 .

[0038] Example 3

[0039] S1: 2g of LLZAO powder and 2g of elemental iodine were ball-milled at 600r / min for 0.5 hours and then heated at 130℃ for 16 hours in a high-pressure sealed reactor to uniformly deposit iodine onto ceramic powder to obtain solid A; 2g of solid A was reacted with 0.5g of lithium aminohydride and 1g of hydrazine hydrate in 50mL of ethanol, and the mixture was centrifuged, washed, dried, and solid B was collected. Under neon protection, solid B was first dehydrated at 90℃ for 8 hours, and then dehydrated again at 200℃ in a vacuum oven for 16 hours to obtain LiI-coated LLZAO powder;

[0040] S2: 0.45g LiI-coated LLZAO powder, 0.75g PEO, and 0.075g Li2S8 were dissolved in 9g anhydrous acetonitrile. The mixture was stirred at 60℃ for 12 hours and then allowed to stand to defoam. The defoamed solution was poured onto a polytetrafluoroethylene glass plate, coated evenly with a doctor blade, and dried to obtain a 50μm solid electrolyte membrane. It was then punched into discs for later use.

[0041] S3: Mix and grind 250mg Ketjen black and 750mg elemental sulfur, calcine at 155℃ for 12h to obtain a sulfur-carbon composite cathode material; dissolve 180mg of the sulfur-carbon composite material and 20mg of carboxymethyl cellulose lithium / styrene-butadiene rubber composite binder in 4g of water to make a slurry, coat the slurry on conductive aluminum foil, and dry to obtain a cathode sheet. Cut the prepared cathode sheet into a 12mm diameter circular sheet as the positive electrode of the battery, cut the prepared PEO-based solid electrolyte into a 16mm diameter circular sheet as the separator and electrolyte of the battery, and cut copper foil into a 16mm diameter circular sheet as the negative electrode of the battery. In a glove box filled with argon atmosphere and with water and oxygen content both below 0.01ppm, seal and assemble CR2032 type button batteries in the following order: cathode shell, positive electrode, solid electrolyte, negative electrode, steel sheet, gasket, and negative electrode shell.

[0042] After battery assembly, it was left to stand at 60℃ for 10 hours before charge-discharge testing. The discharge specific capacity after 100 cycles at a voltage of 1.7-2.8V and a current density of 0.5C was 1010.8 mAh g. -1 Meanwhile, electrochemical impedance spectroscopy revealed a battery resistance R of approximately 125 Ω. With a positive electrode containing 5 mg of high-quality sulfur, the discharge specific capacity after 100 cycles at a 0.5C current density was 612.4 mAh g⁻¹. -1 .

[0043] Example 4

[0044] S1: 1g of LLSNO powder and 2g of elemental iodine were ball-milled at 450r / min for 2.5 hours and mixed. The mixture was then heated at 70℃ for 14 hours in a high-pressure sealed reactor to uniformly deposit iodine onto ceramic powder, yielding solid A. 2g of solid A was reacted with 0.2g of lithium sulfate and 0.4g of hydrazine hydrate in 30mL of chloroform. The mixture was centrifuged, washed, and dried to collect solid B. Under helium protection, solid B underwent a first dehydration at 110℃ for 15 hours, followed by a second high-temperature dehydration at 200℃ for 16 hours in a vacuum oven to obtain LiI-coated LLSNO powder.

[0045] S2: 0.75g LiI coated with LLSNO powder, 0.75g PEO and 0.075g Li2S5 were dissolved in 9g anhydrous acetonitrile. The mixture was stirred at 60℃ for 12h, then allowed to stand to defoam. The defoamed solution was poured onto a polytetrafluoroethylene glass plate, coated evenly with a doctor blade, and dried to obtain a 55μm solid electrolyte membrane. It was then punched into discs for later use.

[0046] S3: Mix and grind 250mg Ketjen black and 750mg elemental sulfur, calcine at 155℃ for 12h to obtain a sulfur-carbon composite cathode material; dissolve 180mg of the sulfur-carbon composite material and 20mg of PEO binder in 4g of water to make a slurry, coat the slurry on conductive aluminum foil, and dry to obtain a cathode sheet. Cut the prepared cathode sheet into a 12mm diameter circular sheet as the positive electrode of the battery, cut the prepared PEO-based solid electrolyte into a 16mm diameter circular sheet as the separator and electrolyte of the battery, and cut copper foil into a 16mm diameter circular sheet as the negative electrode of the battery. In a glove box filled with argon atmosphere and with water and oxygen content both below 0.01ppm, seal and assemble the CR2032 type coin cell in the following order: cathode shell, positive electrode, solid electrolyte, negative electrode, steel sheet, gasket, and negative electrode shell.

[0047] After battery assembly, it was left to stand at 60℃ for 10 hours before charge-discharge testing. The discharge specific capacity after 100 cycles at a voltage of 1.7-2.8V and a current density of 0.5C was 945.6 mAh g. -1 Meanwhile, electrochemical impedance spectroscopy revealed a battery resistance R of approximately 179 Ω. With a positive electrode containing 5 mg of high-quality sulfur, the discharge specific capacity after 100 cycles at a 0.5C current density was 528.5 mAh g. -1 .

[0048] Comparative Example 1

[0049] S1: Dissolve 0.15g LLZTO powder, 0.3g LiTFSI, and 0.75g PEO in 9g anhydrous acetonitrile. Stir at 60℃ for 12h, then allow to stand to defoam. Pour the defoamed solution onto a polytetrafluoroethylene glass plate, coat evenly with a doctor blade, and dry to obtain a 50μm solid electrolyte membrane. Punch into discs for later use.

[0050] S2: Mix and grind 250mg Ketjen black and 750mg elemental sulfur, calcine at 155℃ for 12h to obtain a sulfur-carbon composite cathode material; dissolve 180mg of the sulfur-carbon composite material and 20mg of polyvinylidene fluoride binder in 4g of water to make a slurry, coat the slurry on conductive aluminum foil, and dry to obtain a cathode sheet. Cut the prepared cathode sheet into a 12mm diameter circular sheet as the positive electrode of the battery, cut the prepared PEO-based solid electrolyte into a 16mm diameter circular sheet as the separator and electrolyte of the battery, and cut copper foil into a 16mm diameter circular sheet as the negative electrode of the battery. In a glove box filled with argon atmosphere and with water and oxygen content both below 0.01ppm, seal and assemble CR2032 type button batteries in the following order: cathode shell, positive electrode, solid electrolyte, negative electrode, steel sheet, gasket, and negative electrode shell.

[0051] After battery assembly, it was left to stand at 60℃ for 10 hours before charge-discharge testing. The discharge specific capacity after 100 cycles at a voltage of 1.7-2.8V and a current density of 0.5C was 161.5 mAh g. -1 Meanwhile, electrochemical impedance spectroscopy revealed a battery resistance R of approximately 545 Ω. With a positive electrode containing 5 mg of high-quality sulfur, the discharge specific capacity after 80 cycles at a 0.5C current density was 128.1 mAh g⁻¹. -1 .

[0052] Comparative Example 2

[0053] S1: Dissolve 0.3g LiFSI, 0.75g PEO, and 0.075g Li2S6 in 9g anhydrous acetonitrile. Stir at 60℃ for 12h, then allow to stand to defoam. Pour the defoamed solution onto a polytetrafluoroethylene glass plate, coat it evenly with a doctor blade, and dry to obtain a 50μm solid electrolyte membrane. Punch it into a disc for later use.

[0054] S3: Mix and grind 250mg Ketjen black and 750mg elemental sulfur, calcine at 155℃ for 12h to obtain a sulfur-carbon composite cathode material; dissolve 180mg of the sulfur-carbon composite material and 20mg of polymethyl methacrylate binder in 4g of water to make a slurry, coat the slurry on conductive aluminum foil, and dry to obtain a cathode sheet. Cut the prepared cathode sheet into a 12mm diameter circular sheet as the positive electrode of the battery, cut the prepared PEO-based solid electrolyte into a 16mm diameter circular sheet as the separator and electrolyte of the battery, and cut copper foil into a 16mm diameter circular sheet as the negative electrode of the battery. In a glove box filled with argon atmosphere and with water and oxygen content both below 0.01ppm, seal and assemble CR2032 type button batteries in the following order: cathode shell, positive electrode, solid electrolyte, negative electrode, steel sheet, gasket, and negative electrode shell.

[0055] After battery assembly, it was left to stand at 60℃ for 10 hours before charge-discharge testing. The discharge specific capacity after 50 cycles at a voltage of 1.7-2.8V and a current density of 0.5C was 229.8 mAh g. -1 Meanwhile, electrochemical impedance spectroscopy revealed a battery resistance R of approximately 716 Ω. With a positive electrode containing 5 mg of high-quality sulfur, the discharge specific capacity after 100 cycles at a 0.5C current density was 70.0 mAh g. -1 .

[0056] Comparative Example 3

[0057] S1: Dissolve 0.3g LiI, 0.4g LLZTO, 0.75g PEO, and 0.075g Li2S6 in 9g anhydrous acetonitrile. Stir at 60℃ for 12h, then allow to stand to defoam. Pour the defoamed solution onto a polytetrafluoroethylene glass plate, coat it evenly with a doctor blade, and dry to obtain a 50μm solid electrolyte membrane. Punch it into a disc for later use.

[0058] S3: Mix and grind 250mg Ketjen black and 750mg elemental sulfur, calcine at 155℃ for 12h to obtain a sulfur-carbon composite cathode material; dissolve 180mg of the sulfur-carbon composite material and 20mg of polymethyl methacrylate binder in 4g of water to make a slurry, coat the slurry on conductive aluminum foil, and dry to obtain a cathode sheet. Cut the prepared cathode sheet into a 12mm diameter circular sheet as the positive electrode of the battery, cut the prepared PEO-based solid electrolyte into a 16mm diameter circular sheet as the separator and electrolyte of the battery, and cut copper foil into a 16mm diameter circular sheet as the negative electrode of the battery. In a glove box filled with argon atmosphere and with water and oxygen content both below 0.01ppm, seal and assemble CR2032 type button batteries in the following order: cathode shell, positive electrode, solid electrolyte, negative electrode, steel sheet, gasket, and negative electrode shell.

[0059] After battery assembly, it was left to stand at 60℃ for 10 hours before charge-discharge testing. The discharge specific capacity after 100 cycles at a voltage of 1.7-2.8V and a current density of 0.5C was 232.8 mAh g. -1 Meanwhile, electrochemical impedance spectroscopy revealed a battery resistance R of approximately 716 Ω. With a positive electrode containing 4 mg of high-quality sulfur, the discharge specific capacity after 35 cycles at a 0.5C current density was 41.1 mAh g⁻¹. -1 .

Claims

1. A method for preparing a PEO-based solid-state lithium-sulfur battery without a negative electrode, characterized in that... Preparation of PEO-based solid electrolyte membranes Includes the following steps: S1: Inorganic garnet-type ceramic powder is ball-milled and mixed with elemental iodine, wherein the inorganic ceramic powder is at least one of lithium lanthanum zirconium gallium oxide LLZGO, lithium lanthanum zirconium aluminum oxide LLZAO, lithium lanthanum zirconium oxide LLZO, lithium lanthanum zirconium niobium oxide LLZNO, lithium lanthanum zirconium scandium oxide LLZSO, lithium lanthanum tin niobium oxide LLSNO, lithium lanthanum tin tantalum oxide LLSTO, and lithium lanthanum zirconium tantalum oxide LLZTO. The mass ratio of elemental iodine to inorganic ceramic powder is 1:2-0.

5. Subsequently, the mixture is heated in a high-pressure sealed reactor to sublimate the iodine and uniformly deposit it on the ceramic powder to obtain solid A. S2: In S1, solid A is obtained and reacts fully with an inorganic compound of lithium and hydrazine hydrate in a solvent. The inorganic compound of lithium is at least one of lithium hydroxide, lithium sulfate, lithium carbonate, lithium amino, and lithium imino. Solid B is collected by centrifugation, washing, drying and then dehydrating solid B at high temperature for the first time under a protective atmosphere. Solid B is then dehydrated at high temperature for the second time in a vacuum oven to obtain lithium iodide-coated ceramic powder. S3: In an argon-filled glove box, add the lithium iodide-coated ceramic powder, long-chain lithium polysulfide, and PEO prepared in S2 to the solvent, mix and stir, coat it on a glass plate and dry it to obtain the PEO-based solid electrolyte.

2. The method for preparing a PEO-based solid-state lithium-sulfur battery without a negative electrode according to claim 1, characterized in that, In step S1, the ball mill speed is 400-600 r / min, the ball milling time is 0.5-3 h, the oven heating temperature is 70-150℃, and the heating time is 4-16 h.

3. The method for preparing a PEO-based solid-state lithium-sulfur battery without a negative electrode according to claim 1, characterized in that, In step S2, the mass ratio of solid A to the inorganic compound of lithium to hydrazine hydrate is 1:0.05-0.25:0.1-0.

5.

4. The method for preparing a PEO-based solid-state lithium-sulfur battery without a negative electrode according to claim 1, characterized in that, In step S2, the solvent is at least one of methanol, water, dimethyl sulfoxide, N,N-dimethylformamide, ethanol, diethyl ether, chloroform, acetone, and toluene; the mass ratio of solid A to the solvent is 1:25-50.

5. The method for preparing a PEO-based solid-state lithium-sulfur battery without a negative electrode according to claim 1, characterized in that, In step S2, the protective gas is at least one of helium, argon, nitrogen, and neon; the dehydration temperature is 100-180℃; and the dehydration time is 8-16 hours.

6. The method for preparing a PEO-based solid-state lithium-sulfur battery without a negative electrode according to claim 1, characterized in that, In step S3, the lithium polysulfide is at least one of Li2S4, Li2S5, Li2S6, Li2S7 and Li2S8; the mass ratio of PEO to lithium iodide-coated ceramic powder to lithium polysulfide is 5:1-5:0.1-1.

7. The method for preparing a PEO-based solid-state lithium-sulfur battery without a negative electrode according to claim 1, characterized in that, In step S3, the thickness of the solid electrolyte membrane is 40-60 μm.

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