Cerium-based inorganic filler / P (VDF-HFP)-based polymer solid electrolyte and preparation method and application thereof

Abstract

The invention discloses a cerium-based inorganic filler / P (VDF-HFP)-based polymer solid electrolyte as well as a preparation method and application thereof. In the cerium-based inorganic filler / P (VDF-HFP)-based polymer solid electrolyte, the cerium-based inorganic filler is uniformly distributed in the P (VDF-HFP)-based polymer solid electrolyte; the cerium-based inorganic filler is obtained by calcining Ce-BTC MOF in an argon protective atmosphere. The invention provides an application of the cerium-based inorganic filler / P (VDF-HFP)-based polymer solid electrolyte in a lithium-sulfur battery, and also provides the lithium-sulfur battery. The polymer solid electrolyte provided by the invention has high ionic conductivity, high electrochemical window, long-time cycling stability to a lithium negative electrode, low overpotential, high ion transference number and high limiting current density, and the obtained lithium-sulfur battery has more excellent rate capability, lower polarization and obviously reduced activation energy.

Description

Technical Field

[0001] This invention relates to a cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte, its preparation method, and its application. Background Technology

[0002] The rapid development of electronic devices and electric vehicles has brought greater challenges to energy systems. To meet the demand for longer driving range, there is an urgent need for batteries with higher energy density. Lithium metal has advantages such as high theoretical specific capacity and low reduction potential, making it one of the ideal anode materials for high-energy-density lithium batteries. However, liquid electrolytes have poor compatibility with lithium metal, easily triggering side reactions and leading to the growth of lithium dendrites, which limits the application of lithium metal. In contrast, solid electrolytes not only have good compatibility with lithium metal, but also avoid safety hazards such as electrolyte leakage and combustion, and are expected to enable the application of high-performance lithium batteries. At the same time, lithium-sulfur batteries have attracted much attention from researchers and the market due to their advantages such as high specific capacity, high energy density, abundant elemental sulfur reserves, low price, and environmental friendliness. However, a series of problems seriously hinder their application: 1. Shuttle effect; 2. Poor conductivity of elemental sulfur and the final discharge products (Li2S2 and Li2S); 3. Volume effect.

[0003] Filler-modified P(VDF-HFP)-based polymer solid electrolytes, when applied to lithium-ion batteries, hold promise as an ideal solution to the aforementioned challenges. Solid electrolytes are mainly classified into two categories: inorganic electrolytes and polymer-based electrolytes. Compared to inorganic electrolytes, polymer-based electrolytes offer significant advantages in terms of flexibility, processability, and cost. Among common polymer matrices, different polymers exhibit significant performance differences due to variations in their chain segment structural units. The C-F bonds in polyvinylidene fluoride-hexafluoropropylene (P(VDF-HFP)) provide excellent thermal stability and a wide electrochemical stability window (>4.5V). Its high dielectric constant facilitates the dissociation of lithium salts, while its rigid-flexible chain segment structure not only ensures good film formation but also imparts sufficient flexibility to the electrolyte. These properties make P(VDF-HFP) one of the ideal polymer-based electrolyte materials. Sulfurized polyacrylonitrile (PPI) has attracted much attention as one of the most popular cathode materials in lithium-sulfur batteries due to the following advantages: the solid-solid conversion process does not produce soluble lithium polysulfides, eliminating the shuttle effect, and the conjugated framework C=C and C=N participate in lithium storage. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte, its preparation method, its application in lithium-sulfur batteries, and a lithium-sulfur battery.

[0005] In a first aspect, the present invention provides a cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte, wherein the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte is composed of a P(VDF-HFP)-based polymer solid electrolyte and a cerium-based inorganic filler, wherein the cerium-based inorganic filler is uniformly distributed in the P(VDF-HFP)-based polymer solid electrolyte, and the cerium-based inorganic filler accounts for 7.5-12.5% ​​of the mass of P(VDF-HFP) in the P(VDF-HFP)-based polymer solid electrolyte;

[0006] The cerium-based inorganic filler was prepared by the following method: Ce-BTC MOF was placed in a tube furnace and calcined at 500-700℃ in an argon protective atmosphere, with a heating rate of 5-8℃ / min, for 3-5 hours. After calcination, the furnace was cooled until completely cooled to obtain oxygen-vacancy-rich CeO. 2-X @NC black powder is cerium-based inorganic filler.

[0007] The P(VDF-HFP)-based polymer solid electrolyte of this invention comprises P(VDF-HFP) and a lithium salt. The lithium salt may be at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), and lithium bis(fluorosulfonyl)imide (LiFSI). The mass ratio of P(VDF-HFP) to lithium salt is typically between 1:1 and 2:1. In some embodiments, the lithium salt is LiFSI, and the mass ratio of P(VDF-HFP) to LiFSI is between 1.1:1 and 1.9:1, with 1.5:1 being optimal.

[0008] The Ce-BTC MOF described in this invention is a metal-organic framework material with cerium (Ce) as the metal center and pyromellitic acid (BTC) as the organic ligand. It can be referenced in existing literature, such as [Wen,GY;Qiao,QQ;Wang,Y;Yue,K;Yuan,HD;Luo,JM;Liu,YJ;Nlai,JW;Tao,XY. Oxygen Vacancies-Rich CeO]. 2-x[Nanocrystalline Embedded in N-Doped Carbon Matrix toward High-PerformanceLithium-Sulfur Batteries. SMALL, 2025, 21(21):2500848.] Specifically, the Ce-BTC MOF can generally be prepared by the following method: Weigh cerium nitrate, trimellitic acid, and polyvinylpyrrolidone in air, and add them sequentially to methanol to completely dissolve these precursors. After the solution becomes clear, transfer it to a hydrothermal reactor. Place the reactor in an oven and hydrothermally react at 170°C for 20-24 hours. Then cool it to room temperature with the furnace. Centrifuge the resulting reaction solution, discard the supernatant, and retain the bottom precipitate. Add appropriate amounts of ethanol-DMF-ethanol-DMF-ethanol sequentially, repeat the above operation to wash the precipitate, and dry it in air to obtain the Ce-BTC MOF. The preferred mass ratio of cerium nitrate, trimellitic acid, and polyvinylpyrrolidone is 15:125:100.

[0009] The cerium-based inorganic filler of this invention is obtained by calcining Ce-BTC MOF under an argon protective atmosphere. SEM images of the cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte show that the cerium-based inorganic filler is a micron-sized filler. Preferably, the calcination temperature is 600℃ and the calcination time is 4 hours during the preparation of the cerium-based inorganic filler.

[0010] In a second aspect, the present invention provides a method for preparing the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte described in the first aspect, comprising the following steps:

[0011] (1) Obtain Ce-BTC MOF;

[0012] (2) Oxygen-containing vacancies CeO 2-X @Preparation of NC cerium-based inorganic filler: Ce-BTC MOF was placed in a corundum ceramic boat and calcined in a tube furnace at 500-700℃ under an argon protective atmosphere, with a heating rate of 5-8℃ / min. After calcination for 3-5 hours, the furnace was cooled until completely cooled to obtain oxygen-vacancy-rich CeO. 2-X @NC Black Powder;

[0013] (3) Preparation of P(VDF-HFP) based solid electrolyte: P(VDF-HFP), lithium salt and oxygen-vacancy-rich CeO were weighed in an argon glove box environment. 2-X @NC black powder, add organic solvent, seal with sealant to isolate air and stir for 7-10 hours, homogenize to eliminate air bubbles to obtain casting liquid, cast by solution casting method, vacuum dry and cut in argon glove box atmosphere to obtain P(VDF-HFP) based solid electrolyte.

[0014] The preparation of Ce-BTC MOF in step (1) of this invention is as described in the first aspect and will not be repeated here.

[0015] In step (2) of the present invention, the calcination temperature is preferably 600℃ and the calcination time is preferably 4h.

[0016] In some embodiments, the organic solvent in step (3) is a mixture of N,N-dimethylacetamide (DMAC) and tetrahydrofuran (THF), wherein m DMAC :m THF The ratio of P(VDF-HFP) to organic solvent is preferably 2:7-4:7, with 3:7 being optimal. More preferably, the feed ratio of P(VDF-HFP) to organic solvent is 300-500 mg: 6.66-10 ml, with the most preferred ratio being 400 mg: 8.88 ml. Preferably, the vacuum drying conditions are: placing the product in a vacuum oven and sequentially setting the temperature to 30℃, 40℃, 50℃, 60℃, 70℃, and 80℃ for 5 hours each, for a total of 30 hours; or sequentially setting the temperature to 60℃, 70℃ for 8 hours each, and 80℃ for 16 hours, with the former being optimal.

[0017] Thirdly, the present invention provides the application of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte described in the first aspect in lithium-sulfur batteries.

[0018] In some embodiments, the positive electrode active material of the lithium-sulfur battery is sulfurized polyacrylonitrile (SPAN).

[0019] Fourthly, the present invention provides a lithium-sulfur battery comprising a polymer solid electrolyte, wherein the polymer solid electrolyte is the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte described in the first aspect.

[0020] In some embodiments, the positive electrode active material of the lithium-sulfur battery is sulfurized polyacrylonitrile (SPAN).

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: The cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte of the present invention improves the ionic conductivity after the addition of cerium-based inorganic filler, has a high electrochemical window and long-term cycling stability to the lithium anode, and at the same time has low overpotential, high ion transport number and high limiting current density. The resulting lithium-sulfur battery has better rate performance, lower polarization and significantly reduced activation energy. Attached Figure Description

[0022] Figure 1 This is a scanning electron microscope image of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte and its filler prepared in Example 1.

[0023] Figure 2 This is a fitting curve of the electron paramagnetic resonance test results of the oxygen-vacancy CeO2-X@NC cerium-based inorganic filler prepared in Example 1.

[0024] Figure 3 The X-ray diffraction patterns are of the P(VDF-HFP)-based solid electrolyte prepared in the comparative example and the Ce-BTC MOF, CeO2-X@NC, and cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte prepared in Example 1.

[0025] Figure 4 These are temperature-ionic conductivity dot plots of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte prepared in Example 1 and the P(VDF-HFP)-based solid electrolyte prepared in Comparative Example 1.

[0026] Figure 5 This is a linear sweep voltammetry curve of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte prepared in Example 2.

[0027] Figure 6 The graphs show the rate performance test results of the lithium-||SPAN battery (modified sample) prepared in Example 2 and the lithium-||SPAN battery (comparative sample) prepared in Comparative Example 2.

[0028] Figure 7 The figures show the capacity-voltage curves of the lithium||SPAN battery (modified sample) prepared in Example 2 and the lithium||SPAN battery (control sample) prepared in Comparative Example 2.

[0029] Figure 8 This is a comparison chart of the cycle test results of the experimental lithium symmetric battery prepared in Example 3 and the comparative lithium symmetric battery prepared in Comparative Example 3.

[0030] Figure 9 This is the limiting current density test of the experimental sample lithium symmetric battery prepared in Example 4.

[0031] Figure 10 This is a graph showing the lithium-ion transference number of the experimental lithium-symmetric battery prepared in Example 4.

[0032] Figure 11 This is a variable-temperature cyclic voltammetry test result of the experimental lithium||SPAN battery prepared in Example 5.

[0033] Figure 12 The current-temperature graphs are obtained from the variable-temperature cyclic voltammetry test of the experimental lithium||SPAN battery prepared in Example 5 and the comparative lithium||SPAN battery prepared in Comparative Example 5. Detailed Implementation

[0034] The following examples will further illustrate the content of the present invention. However, these examples do not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative effort are still within the scope of protection of the present invention.

[0035] Unless otherwise specified in the embodiments of this invention, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained through conventional technical means or commercially available.

[0036] Some of the raw materials used in the embodiments of this invention are as follows:

[0037] P(VDF-HFP): Hangzhou Shuangmu Chemical Co., Ltd., product number shmu-p875308-5g, specifications: Melt index: 3~8g / 10min; Tm: 138~142℃, pellets;

[0038] Example 1

[0039] 1. Preparation of Ce-BTC MOF: Weigh 150 mg of cerium nitrate, 1250 mg of trimesic acid, and 1000 mg of polyvinylpyrrolidone (average molecular weight 24000) in air. Add these to 50 mg of methanol (chemically pure or higher). Heat in a 40°C water bath with thorough stirring for 30 min until the precursors are completely dissolved and the solution is clear. Transfer the solution to a hydrothermal reactor and place it in an oven at 170°C for 24 h. Then cool to room temperature with the oven. Centrifuge the hydrothermal reaction solution at 5000 rpm for 3 min. Slowly discard the supernatant, retaining the bottom precipitate. Add appropriate amounts of ethanol-DMF-ethanol-DMF-ethanol in sequence, repeating the above steps to wash the precipitate. After washing, dry in air at 70°C to obtain approximately 300 mg of Ce-BTC MOF, which appears as a white powder.

[0040] 2. Oxygen-containing vacancies CeO 2-X @Preparation of NC cerium-based inorganic filler: The Ce-BTC MOF obtained above was placed in a corundum ceramic boat and calcined in a tube furnace at 600℃ under an argon protective atmosphere at a heating rate of 5℃ / min for 4 hours. After calcination, the furnace was cooled until completely cooled to obtain oxygen-vacancy-rich CeO. 2-X @NC black powder, used as cerium-based inorganic filler.

[0041] For oxygen-rich CeO 2-X @NC black powder was analyzed using a paramagnetic resonance (ESR / EPR) spectrometer, model Bruker EMXplus-6 / 1 (Germany). Results are as follows: Figure 2As shown, the results indicate the presence of unpaired electron signals at a g-factor of 2.002, confirming the presence of CeO₂. 2-X The presence of oxygen vacancies in NC cerium-based inorganic fillers. Additionally, if the powder is exposed to air and its temperature exceeds approximately 90°C, it will oxidize, turning its surface white and producing sparks.

[0042] 3. Preparation of cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte: Weigh 400 mg P(VDF-HFP), 266 mg lithium bis(fluorosulfonyl)imide (LIFSI), and 40 mg CeO in an argon glove box environment. 2-X @NC cerium-based inorganic filler, with a mass ratio of P(VDF-HFP):LiFSI:inorganic filler = (1.5:1:0.15), was added to 8.88 ml of a mixture of N,N-dimethylacetamide (DMAC) / tetrahydrofuran (THF) (m DMAC :m THF =3:7), seal with sealing glue to isolate air and stir for 8 hours to homogenize and eliminate air bubbles. Use solution casting method to cast in a 5cm*8cm polypropylene (PP) box, place in a vacuum oven and set to 30℃, 40℃, 50℃, 60℃, 70℃, and 80℃ for 5 hours each for a total of 30 hours to dry. After completion, cut into pieces in an argon glove box atmosphere to obtain cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte.

[0043] The cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte was sputter-coated with gold, and its microstructure was characterized using a field-emission scanning electron microscope (FESEM). The obtained cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte was frozen in liquid nitrogen for 10 min, then cut with a sharp scalpel. Samples were prepared using the cross-section stage provided with the SESEM, and the resulting scanning electron micrographs are shown below. Figure 1 As shown in the photograph, the cross-sectional thickness of the membrane is about 120 μm, and the cross-sectional photograph shows that the particle size of the filler inside the membrane is about 0.6*1.2 micrometers and is uniformly distributed inside the electrolyte.

[0044] Ce-BTC MOF, CeO2-X@NC, and cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte were placed on the sample stage for X-ray diffraction analysis. An X-ray powder diffractometer (Ultima IV, Rigaku Corporation, Japan) was used. The test conditions were: Cu-Ka as the radiation source, incident wavelength of 0.1545 nm, test tube voltage and current of 40 kV and 40 mA respectively, scan rate of 20° / min, and scan range of 10°–80°. The X-ray diffraction pattern of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte is shown below. Figure 3 As shown, due to the addition of cerium-based inorganic filler, the characteristic crystallization peak of P(VDF-HFP) in the 15°-30° range was significantly weakened, indicating that the addition of filler effectively reduced the crystallinity of P(VDF-HFP) polymer.

[0045] 4. Stainless Steel Symmetrical Battery Assembly: Assemble the CR2032 button cell in an argon-filled glove box. Place the stainless steel gasket, cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte, stainless steel gasket, stainless steel spring sheet, and negative electrode shell sequentially and evenly inside the positive electrode shell. Finally, seal the battery on a battery sealing machine at a pressure of 50 kg / cm². 2 .

[0046] The ionic conductivity of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte was measured using electrochemical impedance spectroscopy. After assembling the test system into a stainless steel symmetrical cell, electrochemical impedance spectroscopy (EIS) was performed on a CHI660E electrochemical workstation with a frequency range of 10 Hz. -1 -10 6 The Hz, 30-80℃ temperature variation method uses a water bath with thick plastic bags for waterproofing and a holding time of ten minutes. The resulting temperature-ion conductivity curve of the stainless steel symmetrical cell is shown in the figure. Figure 4 As shown, the ionic conductivity gradually increases from 30℃ to 80℃.

[0047] 5. Preparation of SPAN positive electrode: Grind 100mg of SPAN powder (Shenzhen Kejing) and 30mg of conductive carbon black powder. Weigh 30mg of P(VDF-HFP) and 24mg of LiFSI in an argon-filled glove box environment, and add them together with the ground powder to 1.8g of DMAC / THF mixture (m dmac :m THF =3:7), sealed and stirred for 8 hours to homogenize and eliminate air bubbles. The homogenate was then coated onto carbon-coated aluminum foil using a 150μm scraper and dried in a vacuum oven at 60℃ for 14 hours. The resulting electrode had an effective material loading of 0.8 mg / cm³. -2 The pieces are cut in an argon-filled glove box for later assembly of button batteries.

[0048] 6. Assembly of Experimental Lithium-SPAN Battery: Assemble CR2032 button batteries in an argon-filled glove box. Place the prepared SPAN positive electrode sheet into the positive electrode shell, then sequentially and evenly place the cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte, lithium sheet, stainless steel gasket, stainless steel spring sheet, and negative electrode shell. Finally, seal the battery on a battery sealing machine at a pressure of 50 kg / cm². 2 .

[0049] Cyclic voltammetry was performed on a CHI660E electrochemical workstation with a voltage range of 1.0-3.0V and a scan rate of 1mV s⁻¹. The temperature variation method used a water bath with a thick plastic bag for water insulation and a holding time of ten minutes. Figure 11 The results show that the reaction polarization of the experimental lithium||SPAN battery decreases and the reaction activity increases with increasing temperature. The activation energy was calculated by plotting the peak intensity values ​​at each temperature using the Arrhenius formula and comparing the data with those of the control sample.

[0050] Arrhenius formula (integral form): In(k) = In(A) - (Ea / R) x (1 / T),

[0051] Where k is the reaction rate constant, with units of (s). -1 T is the thermodynamic temperature, in Kelvin (k); R is the gas constant, with a value of 8.314 kJ / (mol·K); A is the pre-exponential factor (frequency factor), which is related to the frequency and orientation of molecular collisions, and its unit is the same as k; Ea is the activation energy (the minimum energy required for the reaction during battery charging and discharging), in kilojoules per mole (kJ / mol).

[0052] Figure 12 The results show that the activation energy of the experimental lithium||SPAN battery is 16.9 KJ / mol, which is significantly lower than the 25.13 KJ / mol of the control lithium||SPAN battery, indicating that the addition of cerium-based inorganic filler led to a significant reduction in the activation energy of the redox reaction of the battery.

[0053] Comparative Example 1

[0054] 1. Preparation of Ce-BTC MOF: Same as in Example 1.

[0055] 2. Oxygen-containing vacancies CeO 2-X Preparation of NC cerium-based inorganic filler: Same as in Example 1.

[0056] 3. Preparation of P(VDF-HFP)-based solid electrolyte: Weigh 400 mg of P(VDF-HFP) and 266 mg of lithium bis(fluorosulfonyl)imide (LIFSI) in an argon glove box environment, with a mass ratio of p(VDF-HFP):Lifsi = (1.5:1). Add 8.88 ml of N,N-dimethylacetamide (DMAC) / tetrahydrofuran (THF) mixture (m DMAC :m THF =3:7), seal with sealing glue to isolate air and stir for 8 hours to homogenize and eliminate air bubbles. Use solution casting method to cast in a 5cm*8cm polypropylene (PP) box, place in a vacuum oven and set to 30℃, 40℃, 50℃, 60℃, 70℃, and 80℃ for 5 hours each for a total of 30 hours to dry. After completion, cut into pieces in an argon glove box atmosphere to obtain P(VDF-HFP) based solid electrolyte.

[0057] The P(VDF-HFP)-based solid electrolyte was placed on the sample stage for X-ray diffraction analysis, using the same method as in Example 1. The X-ray diffraction pattern of the P(VDF-HFP)-based solid electrolyte is shown below. Figure 3 As shown.

[0058] 4. Comparative assembly of stainless steel symmetrical battery: Same as in Example 1, except that the electrolyte sheet is replaced with a P(VDF-HFP) based solid electrolyte.

[0059] The ionic conductivity of the P(VDF-HFP)-based solid electrolyte was tested using the AC impedance method, following the same method as in Example 1. The temperature-ionic conductivity plot of the obtained stainless steel symmetrical cell is shown below. Figure 4 As shown.

[0060] From 30°C to 80°C, the ionic conductivity of the P(VDF-HFP)-based solid electrolyte in Comparative Example 1 showed a gradual increasing trend. However, the overall ionic conductivity of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte in Example 1 was higher than that of the P(VDF-HFP)-based solid electrolyte in Comparative Example 1, and the ionic conductivity at 30°C decreased from 10... -3.84 S cm -1 Upgraded to 10 -2.99 S cm -1 This is because the addition of cerium-based inorganic fillers effectively reduces the crystallinity of the P(VDF-HFP) polymer.

[0061] 5. Preparation of SPAN positive electrode: Same as in Example 1.

[0062] 6. Comparative lithium || SPAN battery assembly: Same as Example 5, except that the electrolyte sheet is replaced with a P(VDF-HFP) based solid electrolyte.

[0063] Electrochemical tests were conducted on the lithium-ion SPAN battery using a CHI660E electrochemical workstation to assess its cyclic voltammetry performance. The results are as follows: Figure 12 As shown.

[0064] Example 2

[0065] 1. Preparation of cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte: 300 mg P(VDF-HFP), 266 mg lithium bis(fluorosulfonyl)imide (LIFSI), and 30 mg CeO2 prepared according to the method in Example 1 were weighed in an argon glove box environment. 2-X @NC cerium-based inorganic filler, add 6.66 ml of N,N-dimethylacetamide (DMAC) / tetrahydrofuran (THF) mixture (m DMAC :m THF =2:7), seal with sealing glue to isolate air and stir for 8 hours to homogenize and eliminate air bubbles. Use solution casting method to cast in a 5cm*8cm polypropylene (PP) box and place in a vacuum oven set at 60℃, 70℃ for 8 hours each, and 80℃ for 16 hours. After completion, cut in an argon glove box atmosphere to obtain cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte.

[0066] 2. Preparation of SPAN positive electrode: 90 mg of SPAN powder (Shenzhen Kejing, product code BM.99020201, sulfur content Wt% > 50%) and 30 mg of conductive carbon black powder were ground. In an argon glove box environment, 30 mg of P(VDF-HFP) and 20 mg of LiFSI were weighed and added together with the ground powder to 1.4 g of DMAC / THF mixture (m). dmac :m THF =3:7), sealed and stirred for 6 hours to homogenize and eliminate air bubbles. The homogenate was then coated onto carbon-coated aluminum foil using a 150 μm doctor blade and dried in a vacuum oven at 60℃ for 10 hours. The resulting electrode had a SPAN loading of 0.8 mg / cm³. -2 The pieces are cut in an argon-filled glove box for later assembly of button batteries.

[0067] 3. Lithium-ion SPAN Battery Assembly: Assemble CR2032 button batteries in an argon-filled glove box. Place the prepared SPAN positive electrode sheet into the positive electrode shell, then sequentially and evenly place the cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte, lithium sheet, stainless steel gasket, stainless steel spring sheet, and negative electrode shell. Finally, seal the battery on a battery sealing machine at a pressure of 50 kg / cm². 2 .

[0068] The lithium-ion SPAN battery was tested using the Newway battery testing system to perform charge-discharge cycle tests and assess its rate performance. Figure 6Short-cycle tests were conducted at rates of 0.05C, 0.1C, 0.2C, and 0.5C, with a voltage range of 1-3V. The results showed that the discharge specific capacity of Example 2 battery was higher than that of Comparative Example 2 battery at both high and low rates. The discharge specific capacity remained at 500mAh / g at the initial 0.05C rate, and Example 2 battery was able to return to a discharge specific capacity of 385mAh / g after the 0.5C test. Its charge-discharge curve ( Figure 7 The results show that the polarization of the battery in Example 2 at a rate of 0.05c is less than that of the battery in Comparative Example 2. The addition of filler reduced the polarization, which is attributed to the contribution of the filler to the improvement of ion conductance.

[0069] 4. Lithium || Stainless Steel Battery Assembly: Assemble the CR2032 button cell battery in an argon-filled glove box. Inside the positive electrode shell, sequentially and evenly place the stainless steel gasket, cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte, lithium sheet, stainless steel gasket, stainless steel spring sheet, and negative electrode shell. Finally, seal the battery on a battery sealing machine at a pressure of 50 kg / cm². 2 .

[0070] The electrochemical window of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte was determined using linear sweep voltammetry. After assembling the test system into a lithium-stainless steel battery, linear sweep voltammetry was performed on a CHI660E electrochemical workstation with a voltage range of 5V (open-circuit voltage of the battery). The linear sweep voltammetry curves are shown below. Figure 5 As shown, the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte has a high electrochemical window (>4.5V).

[0071] Comparative Example 2

[0072] 1. Preparation of P(VDF-HFP)-based solid electrolyte: Weigh 300 mg of P(VDF-HFP) and 266 mg of lithium bis(fluorosulfonyl)imide (LIFSI) in an argon glove box environment, and add 6.66 ml of N,N-dimethylacetamide (DMAC) / tetrahydrofuran (THF) mixture (m DMAC :m THF =2:7), seal with sealing glue to isolate air and stir for 8 hours to homogenize and eliminate air bubbles. Use solution casting method to cast in a 5cm*8cm polypropylene (PP) box and place in a vacuum oven set at 60℃, 70℃ for 8 hours each, and 80℃ for 16 hours. After completion, cut into pieces in an argon glove box atmosphere to obtain P(VDF-HFP) based solid electrolyte.

[0073] 2. Preparation of SPAN positive electrode: Grind 90mg of SPAN powder (Shenzhen Kejing) and 30mg of conductive carbon black powder. Weigh 30mg of P(VDF-HFP) and 20mg of LiFSI in an argon glove box environment, and add them together with the ground powder to 1.4g of DMAC / THF mixture (m dmac :m THF =3:7), sealed and stirred for 6 hours to homogenize and eliminate air bubbles. The homogenate was then coated onto carbon-coated aluminum foil using a 150 μm doctor blade and dried in a vacuum oven at 60℃ for 10 hours. The resulting electrode had a SPAN loading of 0.8 mg / cm³. -2 The pieces are cut in an argon-filled glove box for later assembly of button batteries.

[0074] 3. Comparative lithium || SPAN battery assembly: Same as Example 1, except that the electrolyte sheet is replaced with a P(VDF-HFP) based solid electrolyte.

[0075] The lithium-ion SPAN battery was subjected to charge-discharge cycle testing and its rate performance was tested using the Newway battery testing system. The testing method was the same as in Example 2, and the results are as follows. Figure 6 and Figure 7 As shown.

[0076] Example 3

[0077] 1. Preparation of cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte: 500 mg P(VDF-HFP), 266 mg lithium bis(trifluoromethanesulfonyl)imide (LiFSI), and 50 mg CeO2 prepared according to the method in Example 1 were weighed in an argon glove box environment. 2-X @NC cerium-based inorganic filler, add 10 ml of N,N-dimethylacetamide (DMAC) / tetrahydrofuran (THF) mixture (m DMAC :m THF =4:7), seal with sealing glue to isolate air and stir for 7 hours to homogenize and eliminate air bubbles. Use solution casting method to cast in a 5cm*8cm polypropylene (PP) box, place in a vacuum oven and set to 30℃, 40℃, 50℃, 60℃, 70℃, and 80℃ for 5 hours each for a total of 30 hours to dry. After completion, cut into pieces in an argon glove box atmosphere to obtain cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte.

[0078] 2. Preparation of SPAN positive electrode: 100 mg of SPAN powder (Shenzhen Kejing) and 30 mg of conductive carbon black powder were ground. 40 mg of P(VDF-HFP) and 26 mg of LiFSI were weighed in an argon-filled glove box and added together with the ground powder to 1.4 g of DMAC / THF mixture (mdmac:mTHF = 3:7). The mixture was sealed and stirred for 6 hours to homogenize and eliminate air bubbles. The homogenate was then coated onto carbon-coated aluminum foil using a 150 μm doctor blade and dried in a vacuum oven at 60 °C for 9 hours. The resulting electrode had a SPAN loading of 0.9 mg / cm⁻². The electrode was cut into sheets in an argon-filled glove box for subsequent assembly of coin cells.

[0079] 3. Assembly of experimental lithium symmetric batteries: Assemble CR2032 button batteries in an argon-filled glove box. Inside the positive electrode shell, sequentially and evenly place the lithium sheet, cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte, lithium sheet, stainless steel gasket, stainless steel spring sheet, and negative electrode shell. Finally, seal the battery on a battery sealing machine at a pressure of 50 kg / cm². 2 .

[0080] The battery was charged and discharged using the Xinwei Battery Testing System. The test included (1) the lithium symmetric battery at 0.1 mA cm -2 The current density is 0.1 mAh cm⁻¹. -2 Lithium deposition / stripping cycle tests were performed at the areal capacity. Figure 8 The results showed that the control sample experienced a significant increase in overpotential around 1100h, while the experimental sample remained at around 100mV for a long time. Later, due to changes in the temperature control system settings, the change in ambient temperature caused the overpotential to remain stable between 120-140mV for more than 2700h.

[0081] Comparative Example 3

[0082] 1. Preparation of P(VDF-HFP)-based polymer solid electrolyte: Weigh 500 mg P(VDF-HFP), 266 mg lithium bis(trifluoromethanesulfonyl)imide (LiFSI), and 50 mg CeO in an argon glove box environment. 2-X @NC cerium-based inorganic filler, add 10 ml of N,N-dimethylacetamide (DMAC) / tetrahydrofuran (THF) mixture (m DMAC :m THF =4:7), seal with sealing glue to isolate air and stir for 7 hours to homogenize and eliminate air bubbles. Use solution casting method to cast in a 5cm*8cm polypropylene (PP) box, place in a vacuum oven and set to 30℃, 40℃, 50℃, 60℃, 70℃, and 80℃ for 5 hours each for a total of 30 hours to dry. After completion, cut into pieces in an argon glove box atmosphere to obtain cerium-based inorganic filler / P(VDF-HFP) based solid electrolyte.

[0083] 2. Preparation of SPAN positive electrode: 100mg of SPAN powder (Shenzhen Kejing) and 30mg of conductive carbon black powder were ground. 40mg of P(VDF-HFP) and 26mg of LiFSI were weighed in an argon glove box environment and added together with the ground powder to 1.4g of DMAC / THF mixture (mdmac:mTHF=3:7). The mixture was sealed and stirred for 6h to homogenize and eliminate air bubbles. The slurry was then coated onto carbon-coated aluminum foil with a 150μm doctor blade and dried in a vacuum oven at 60℃ for 9h. The resulting electrode had a span loading of 0.9mg / cm-2. The electrode was cut into pieces in an argon glove box for subsequent assembly of coin cells.

[0084] 3. Comparative lithium symmetric battery assembly: Same as Example 3, except that the electrolyte sheet is replaced with a P(VDF-HFP) based solid electrolyte.

[0085] The battery was subjected to charge-discharge cycles using the Newway battery testing system to test its lithium symmetric battery performance. The testing method was the same as in Example 3, and the results are as follows. Figure 8 As shown.

[0086] Example 4

[0087] 1. Preparation of cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte: 400 mg P(VDF-HFP), 266 mg lithium bis(fluorosulfonyl)imide (LIFSI) were weighed in an argon glove box environment, with a mass ratio of P(VDF-HFP):LiFSI = (1.5:1), and 30 mg CeO2 was added. 2-X @NC cerium-based inorganic filler, add 8.88 ml of N,N-dimethylacetamide (DMAC) / tetrahydrofuran (THF) mixture (m DMAC :m THF =2:7), seal with sealing glue to isolate air and stir for 8 hours to homogenize and eliminate air bubbles. Use solution casting method to cast in a 5cm*8cm polypropylene (PP) box, place in a vacuum oven and set to 30℃, 40℃, 50℃, 60℃, 70℃, and 80℃ for 5 hours each for a total of 30 hours to dry. After completion, cut into pieces in an argon glove box atmosphere to obtain cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte.

[0088] 2. Preparation of SPAN positive electrode: 100mg of SPAN powder (Shenzhen Kejing) and 30mg of conductive carbon black powder were ground. 40mg of P(VDF-HFP) and 26mg of LiFSI were weighed in an argon glove box environment and added together with the ground powder to 1.4g of DMAC / THF mixture (mdmac:mTHF=3:7). The mixture was sealed and stirred for 6h to homogenize and eliminate air bubbles. The slurry was then coated onto carbon-coated aluminum foil with a 150μm doctor blade and dried in a vacuum oven at 60℃ for 9h. The resulting electrode had a span loading of 0.9mg / cm-2. The electrode was cut into pieces in an argon glove box for subsequent assembly of coin cells.

[0089] 3. Assembly of experimental lithium symmetric batteries: Assemble CR2032 button batteries in an argon-filled glove box. Inside the positive electrode shell, sequentially and evenly place the lithium sheet, cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte, lithium sheet, stainless steel gasket, stainless steel spring sheet, and negative electrode shell. Finally, seal the battery on a battery sealing machine at a pressure of 50 kg / cm². 2 .

[0090] The battery was subjected to charge-discharge cycles using the Xinwei Battery Testing System. The lithium symmetric battery was tested at 0.05, 0.1, 0.2, and 0.3 mA cm⁻¹. -2 The limiting current density was tested at similar current densities to determine the limiting current density of the cerium-based inorganic filler / P(VDF-HFP) based polymer solid electrolyte. The results are as follows: Figure 9 The experiment showed that the limiting current density reached 1.2 mA cm⁻¹. -2 The corresponding voltage reached 4.5V, which matches the electrochemical window in Example 2, indicating that the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte has a high electrochemical window and limiting current density tolerance, demonstrating feasibility for high-voltage platform adaptation. The lithium-ion transference number of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte was tested and calculated to be 0.84. Figure 10 As shown.

Claims

1. A cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte, characterized in that: The cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte is composed of P(VDF-HFP)-based polymer solid electrolyte and cerium-based inorganic filler. The cerium-based inorganic filler is uniformly distributed in the P(VDF-HFP)-based polymer solid electrolyte, and the cerium-based inorganic filler accounts for 7.5-12.5% ​​of the mass of P(VDF-HFP) in the P(VDF-HFP)-based polymer solid electrolyte. The cerium-based inorganic filler was prepared by the following method: Ce-BTC MOF was placed in a tube furnace and calcined at 500-700℃ in an argon protective atmosphere, with a heating rate of 5-8℃ / min. After calcination for 3-5 hours, the furnace was cooled until completely cooled to obtain oxygen-vacancy-rich CeO. 2-X @NC black powder is cerium-based inorganic filler.

2. The cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte as described in claim 1, characterized in that: The P(VDF-HFP)-based polymer solid electrolyte comprises P(VDF-HFP) and a lithium salt, wherein the lithium salt is at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, and lithium bis(fluorosulfonyl)imide, and the mass ratio of P(VDF-HFP) to the lithium salt is 1:1 to 2:

1.

3. The cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte as described in claim 1, characterized in that: The lithium salt is LiFSI, and the mass ratio of P(VDF-HFP) to LiFSI is 1.1:1-1.9:1, with 1.5:1 being optimal.

4. The cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte as described in claim 1, characterized in that: In the preparation process of cerium-based inorganic fillers, the calcination temperature is 600℃ and the calcination time is 4h.

5. A method for preparing a cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte as described in any one of claims 1-4, characterized in that: The preparation method includes the following steps: (1) Obtain Ce-BTC MOF: (2) Ce-BTC MOF was placed in a corundum ceramic boat and calcined in a tube furnace under an argon protective atmosphere at 500-700℃ with a heating rate of 5-8℃ / min for 3-5 hours. After calcination, the furnace was cooled until completely cooled to obtain CeO rich in oxygen vacancies. 2-X @NC black powder, which is cerium-based inorganic filler; (3) Preparation of P(VDF-HFP) based solid electrolyte: P(VDF-HFP), lithium salt and oxygen-vacancy-rich CeO were weighed in an argon glove box environment. 2-X @NC black powder, add organic solvent, seal with sealant to isolate air and stir for 7-10 hours, homogenize to eliminate air bubbles to obtain casting liquid, cast by solution casting method, vacuum dry and cut in argon glove box atmosphere to obtain P(VDF-HFP) based solid electrolyte.

6. The preparation method according to claim 5, characterized in that: The organic solvent in step (3) is a mixture of N,N-dimethylacetamide (DMAC) and tetrahydrofuran (THF), wherein m DMAC :m THF =2:7-4:7, 3:7 is optimal; the feed ratio of P(VDF-HFP) to organic solvent is 300-500mg:6.66-10ml.

7. The preparation method according to claim 5, characterized in that: In step (3), the vacuum drying conditions are as follows: place the product in a vacuum oven and set it to 30℃, 40℃, 50℃, 60℃, 70℃ and 80℃ for 5 hours each, for a total of 30 hours, or set it to 60℃ and 70℃ for 8 hours each, and then dry at 80℃ for 16 hours.

8. The application of the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte as described in any one of claims 1-4 in lithium-sulfur batteries.

9. The application as described in claim 8, characterized in that: The positive electrode active material of the lithium-sulfur battery is sulfurized polyacrylonitrile.

10. A lithium-sulfur battery, comprising a polymer solid electrolyte, characterized in that: The polymer solid electrolyte is the cerium-based inorganic filler / P(VDF-HFP)-based polymer solid electrolyte as described in any one of claims 1-4.

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