Composite solid electrolyte, preparation method thereof, solid-state battery and electric device

Abstract

The application discloses a composite solid electrolyte and a preparation method thereof, a solid-state battery and an electric device. The composite solid electrolyte comprises modified ceramic particles, a polymer matrix and a lithium salt, the modified ceramic particles are ceramic particles modified by a functional polymer, the functional polymer comprises at least one of polyethylene glycol monomethyl ether methacrylate or polymethyl methacrylate, and the ceramic particles comprise a compound with a chemical formula of Li 7‑x La3Zr 2‑x M x O 12 , wherein 0<=x<=2, and M comprises one or more of Ta, Al, Zr, Sn, Nb, Y or W. The application improves the interfacial compatibility of the polymer matrix and the ceramic particles by grafting modification of the ceramic particles, makes the high content of ceramic particles uniformly distributed in the polymer matrix, and thus makes the composite solid electrolyte have excellent electrochemical performance.

Description

Technical Field

[0001] This application relates to the field of lithium-ion solid-state battery technology, specifically to a composite solid-state electrolyte and its preparation method, a solid-state battery, and an electrical device thereof. Background Technology

[0002] Rechargeable lithium-ion batteries are currently a crucial component of portable electronic products and new energy vehicles. However, existing commercial lithium-ion batteries can no longer meet the growing demand, making the development of safer, lower-cost batteries with higher energy density and longer cycle life an urgent priority. Lithium metal possesses an extremely high theoretical specific capacity (3860 mAh·g). -1 Low density (0.59 g·cm³) -3 Liquid electrolytes have attracted attention due to their high electrochemical reactivity and low redox potential (-3.04V vs. standard hydrogen electrode). However, they still face several challenges in practical applications. The high chemical reactivity of liquid electrolytes and the uncontrollable lithium dendrite growth during cycling lead to numerous safety issues and significant losses. Solid electrolytes, with their high electrochemical stability and good mechanical strength, are considered the most promising materials for addressing these problems.

[0003] Solid-state electrolytes are classified into polymer electrolytes and inorganic ceramic electrolytes. Polymer electrolytes offer excellent safety performance, processability, and good contact with the electrode interface; however, they have low ionic conductivity at room temperature, making it difficult to suppress lithium dendrite growth. Inorganic ceramic electrolytes possess high ionic conductivity and a large lithium-ion transference number; however, they suffer from poor interfacial contact with the electrode, high rigidity, and poor processability. These drawbacks hinder the large-scale application of both polymer and inorganic ceramic electrolytes.

[0004] Adding ceramic particles to a polymer matrix combines the advantages of both, mitigating their weaknesses and resulting in composite solid-state electrolytes with high ionic conductivity, good mechanical properties, and a wide electrochemical window. However, ceramic particles tend to aggregate in the polymer matrix, disrupting the percolation network in the composite solid-state electrolyte and leading to a decrease in ionic conductivity. Therefore, to achieve high ionic conductivity, most composite solid-state electrolytes contain only a small amount of ceramic particles, which significantly limits their electrochemical performance. Thus, improving the interfacial compatibility between the polymer matrix and ceramic particles, increasing the loading of ceramic particles, and ensuring their uniform distribution are crucial for enhancing the overall performance of composite solid-state electrolytes and their application in batteries. Summary of the Invention

[0005] This application provides a composite solid electrolyte and its preparation method, solid battery and electrical device, which solves the problems of poor interfacial compatibility between polymer matrix and ceramic particles and low loading of ceramic particles in existing composite solid electrolytes.

[0006] The composite solid electrolyte according to the first embodiment of this application includes modified ceramic particles, a polymer matrix, and a lithium salt. The modified ceramic particles are ceramic particles grafted with functionalized polymers. The functionalized polymers include at least one of polyethylene glycol monomethyl ether methacrylate or polymethyl methacrylate. The ceramic particles contain lithium salts with the chemical formula Li. 7- x La3Zr 2-x M x O 12 Compounds wherein 0 ≤ x ≤ 2, and M includes one or more of Ta, Al, Zr, Sn, Nb, Y or W.

[0007] Optionally, in other embodiments of this application, the polymer matrix includes one or more of polyethylene oxide, polyvinylidene fluoride, or poly(vinylidene fluoride-co-hexafluoropropylene).

[0008] Optionally, in other embodiments of this application, the lithium salt includes lithium bis(trifluoromethanesulfonylimide).

[0009] Optionally, in other embodiments of this application, the modified ceramic particles account for 50% to 70% of the total mass of the polymer matrix and lithium salt.

[0010] The method for preparing the composite solid electrolyte according to the second embodiment of this application includes:

[0011] Modified ceramic particles, polymer matrix and lithium salt are dissolved in a solvent and stirred to obtain a slurry;

[0012] The slurry is coated onto the mold, dried, and the solvent is removed to obtain a composite solid electrolyte.

[0013] The modified ceramic particles are ceramic particles grafted with functionalized polymers. The functionalized polymers include at least one of polyethylene glycol monomethyl ether methacrylate or polymethyl methacrylate. The ceramic particles contain materials with the chemical formula Li. 7-x La3Zr 2-x M x O 12 Compounds wherein 0 ≤ x ≤ 2, and M includes one or more of Ta, Al, Zr, Sn, Nb, Y, or W.

[0014] Optionally, in other embodiments of this application, the method for preparing the modified ceramic particles includes:

[0015] Provide precursor solution;

[0016] Ceramic particles were added to the precursor solution, stirred, and silanized to obtain the intermediate product.

[0017] The intermediate product, functionalized polymer, and azobisisobutyronitrile were dispersed in a solvent and reacted under a nitrogen atmosphere to obtain modified ceramic particles.

[0018] Optionally, in other embodiments of this application, the method for preparing the precursor solution includes: mixing propyl 3-(trimethoxysilyl)methacrylate, acetic acid, deionized water and ethanol to obtain the precursor solution.

[0019] Optionally, in other embodiments of this application, the mass ratio of intermediate product to functionalized polymer is 1:(9-11).

[0020] The solid-state battery according to the third embodiment of this application includes the composite solid-state electrolyte described above.

[0021] The electrical device according to the fourth embodiment of this application includes the solid-state battery described above, and the solid-state battery serves as the power supply for the electrical device.

[0022] The composite solid electrolyte according to the embodiments of this application has at least the following technical effects:

[0023] (1) The composite solid electrolyte of this application includes modified ceramic particles, polymer matrix and lithium salt. The modified ceramic particles are ceramic particles that have been functionalized by polymer grafting. By grafting the ceramic particles, the interfacial compatibility between the polymer matrix and the ceramic particles is improved, so that the high content of ceramic particles is evenly distributed in the polymer matrix.

[0024] (2) By grafting and modifying the ceramic particles, the harmful impurity lithium carbonate on the surface of the ceramic particles was eliminated.

[0025] (3) By grafting and modifying the ceramic particles, the interaction between the polymer and the ceramic particles is improved, and the prepared composite solid electrolyte has good mechanical properties. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a TEM image of the modified ceramic particles prepared in Example 1 of this application;

[0028] Figure 2 This is an XPS image (C 1s) of the modified ceramic particles prepared in Example 1 of this application;

[0029] Figure 3This is an XPS image (O 1s) of the modified ceramic particles prepared in Example 1 of this application;

[0030] Figure 4 This is a SEM image (100 μm) of the surface of the composite solid electrolyte membrane prepared in Example 1 of this application;

[0031] Figure 5 This is a SEM image (20 μm) of the surface of the composite solid electrolyte membrane prepared in Example 1 of this application;

[0032] Figure 6 This is a mechanical property diagram of the composite solid electrolyte membrane prepared in Example 1 of this application;

[0033] Figure 7 This refers to the impedance change of the composite solid electrolyte membrane prepared in Example 1 of this application at 30-90°C;

[0034] Figure 8 This refers to the change in conductivity of the composite solid electrolyte membrane prepared in Example 1 of this application at 30-90°C;

[0035] Figure 9 This is a constant current charge-discharge test diagram of the lithium symmetric battery prepared in Example 1 of this application;

[0036] Figure 10 The cycling performance of the Li / LiFePO4 battery prepared in Example 1 of this application at 1C (60°C);

[0037] Figure 11 The charge-discharge curves of the Li / LiFePO4 battery prepared in Example 1 of this application at 1C (60°C) are shown.

[0038] Figure 12 This is a rate performance diagram of the Li / LiFePO4 battery prepared in Example 1 of this application;

[0039] Figure 13 This is a TEM image of the modified ceramic particles prepared in Example 2 of this application;

[0040] Figure 14 This is the XPS image (C 1s) of the modified ceramic particles prepared in Example 2 of this application;

[0041] Figure 15 This is the XPS image (O 1s) of the modified ceramic particles prepared in Example 2 of this application;

[0042] Figure 16 This is a SEM image of the surface of the composite solid electrolyte membrane prepared in Example 2 of this application;

[0043] Figure 17This is a mechanical property diagram of the composite solid electrolyte membrane prepared in Example 2 of this application;

[0044] Figure 18 This refers to the impedance change of the composite solid electrolyte membrane prepared in Example 2 of this application at 30-90°C;

[0045] Figure 19 This refers to the change in conductivity of the composite solid electrolyte membrane prepared in Example 2 of this application at 30-90°C;

[0046] Figure 20 This is a constant current charge-discharge test diagram of the lithium symmetric battery prepared in Example 2 of this application;

[0047] Figure 21 The cycling performance of the Li / LiFePO4 battery prepared in Example 2 of this application at 1C (60°C);

[0048] Figure 22 The charge-discharge curves of the Li / LiFePO4 battery prepared in Example 2 of this application at 1C (60°C) are shown.

[0049] Figure 23 This is a rate performance diagram of the Li / LiFePO4 battery prepared in Example 2 of this application;

[0050] Figure 24 This is a TEM image of the modified ceramic particles prepared in Example 3 of this application;

[0051] Figure 25 This is a SEM image of the surface of the composite solid electrolyte membrane prepared in Example 3 of this application;

[0052] Figure 26 This is a mechanical property diagram of the composite solid electrolyte membrane prepared in Example 3 of this application;

[0053] Figure 27 This refers to the change in conductivity of the composite solid electrolyte membrane prepared in Example 3 of this application at 30-90°C;

[0054] Figure 28 This is a constant current charge-discharge test diagram of the lithium symmetric battery prepared in Example 3 of this application;

[0055] Figure 29 The cycling performance of the Li / LiFePO4 battery prepared in Example 3 of this application at 1C (60°C);

[0056] Figure 30 This is a rate performance diagram of the Li / LiFePO4 battery prepared in Example 3 of this application. Detailed Implementation

[0057] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0058] This application provides a composite solid electrolyte, its preparation method, a solid battery, and an electrical device. These are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments.

[0059] This application provides a composite solid electrolyte comprising modified ceramic particles, a polymer matrix, and a lithium salt. The modified ceramic particles are ceramic particles grafted with functionalized polymers, and the functionalized polymers include at least one of polyethylene glycol monomethyl ether methacrylate or polymethyl methacrylate. The ceramic particles comprise lithium salts with the chemical formula Li. 7-x La3Zr 2- x M x O 12 The compound, wherein 0 ≤ x ≤ 2, and M includes one or more of Ta, Al, Zr, Sn, Nb, Y, or W. The composite solid electrolyte of this application comprises modified ceramic particles, a polymer matrix, and a lithium salt. The modified ceramic particles are ceramic particles grafted with functionalized polymers. By grafting the ceramic particles, the interfacial compatibility between the polymer matrix and the ceramic particles is improved, resulting in a high content of ceramic particles uniformly distributed within the polymer matrix. This eliminates harmful impurities such as lithium carbonate on the surface of the ceramic particles and enhances the interaction between the polymer and the ceramic particles. The prepared composite solid electrolyte exhibits excellent mechanical properties.

[0060] In general, due to the significant surface energy difference between ceramic particles and the polymer matrix, ceramic particles tend to agglomerate in the polymer matrix, making uniform distribution difficult. Grafting functionalized polymers onto the surface of ceramic particles is equivalent to applying a coating. The surface energy difference between the polymer on the particle surface and the polymer matrix is ​​smaller than the difference between the ceramic particles and the polymer matrix. Therefore, the interfacial compatibility of the modified ceramic particles is improved, allowing for uniform distribution within the polymer matrix. Although grafting other polymers onto modified ceramic particles may also improve interfacial compatibility, simply improving interfacial compatibility does not necessarily improve battery performance. Therefore, this application investigated the selection of functionalized polymers and polymer matrices.

[0061] In some embodiments of this application, the polymer matrix includes one or more of polyethylene oxide, polyvinylidene fluoride, or poly(vinylidene fluoride-co-hexafluoropropylene).

[0062] In some embodiments of this application, polyethylene glycol monomethyl ether methacrylate (PEG-MAM methacrylate) is grafted onto the surface of ceramic particles, and then composited with a polymer matrix (polyethylene oxide) to prepare an electrolyte. Both PEG-MAM methacrylate and polyethylene oxide contain EO segments (-OCH2CH2-), and the main structure of both polymers is the EO segment, thus significantly improving interfacial compatibility. Simultaneously, the interaction between the polymer on the particle surface and the polymer matrix is ​​enhanced, and they become entangled and interlocked in the electrolyte, resulting in a significant improvement in mechanical properties. Furthermore, the EO segments facilitate lithium-ion transport, leading to a significant increase in ionic conductivity. Increasing the loading of ceramic particles also significantly increases the lithium-ion transference number. These improvements ultimately result in excellent solid-state battery performance.

[0063] In some embodiments of this application, polymethyl methacrylate (PMMA) was grafted onto the surface of ceramic particles, and then composited with polyvinylidene fluoride (PVDF) to prepare an electrolyte. PMMA exhibits a strong affinity for ceramic particles in solution. Furthermore, the C-O groups in PMMA can react with Li... + Complexation facilitates ion transport at the ceramic particle / polymer matrix interface. Therefore, polymethyl methacrylate (PMMA) was chosen as the functionalized polymer. After forming a composite solid electrolyte with polyvinylidene fluoride (PVDF), the increased affinity of the ceramic particles for the PDF matrix allows for the generation of continuous Li₂O₃. + This improved transport pathway allows the composite electrolyte to exhibit excellent ionic conductivity. Solid-state battery performance is also enhanced.

[0064] In some embodiments of this application, the lithium salt includes lithium bis(trifluoromethanesulfonyl)imide.

[0065] In some embodiments of this application, the modified ceramic particles account for 50% to 70% of the total mass of the polymer matrix and lithium salt. The composite solid electrolyte prepared in this application contains a high content of ceramic particles. The high content of ceramic particles forms a good permeation network in the composite solid electrolyte, constructs new lithium-ion transport channels, and improves ionic conductivity.

[0066] Accordingly, embodiments of this application also provide a method for preparing a composite solid electrolyte, comprising:

[0067] Modified ceramic particles, polymer matrix and lithium salt are dissolved in a solvent and stirred to obtain a slurry;

[0068] The slurry is coated onto the mold, dried, and the solvent is removed to obtain a composite solid electrolyte.

[0069] The modified ceramic particles are ceramic particles grafted with functionalized polymers. The functionalized polymers include at least one of polyethylene glycol monomethyl ether methacrylate or polymethyl methacrylate. The ceramic particles contain materials with the chemical formula Li. 7-x La3Zr 2-x M x O 12 Compounds wherein 0 ≤ x ≤ 2, and M includes one or more of Ta, Al, Zr, Sn, Nb, Y, or W.

[0070] In some embodiments of this application, the method for preparing modified ceramic particles includes:

[0071] Provide precursor solution;

[0072] Ceramic particles were added to the precursor solution, stirred, and silanized to obtain the intermediate product.

[0073] The intermediate product, functionalized polymer, and azobisisobutyronitrile were dispersed in a solvent and reacted under a nitrogen atmosphere to obtain modified ceramic particles.

[0074] In some embodiments of this application, the method for preparing the precursor solution includes: mixing propyl 3-(trimethoxysilyl)methacrylate, acetic acid, deionized water and ethanol to obtain the precursor solution.

[0075] In some embodiments of this application, the mass ratio of intermediate product to functionalized polymer can be 1:(9-11); the mass ratio can also be 1:10. If the amount of functionalized polymer is too high, it will hinder the conductive channels of the ceramic particles themselves, causing the ceramic particles to lose their function, which is detrimental to the solid-state battery. If the amount of functionalized polymer is too low, the amount of grafting will be very small, and the effect will be minimal, insufficient to have a positive impact on the performance of the solid-state battery.

[0076] In specific implementation, the preparation methods of composite solid electrolytes include:

[0077] 1) Preparation of precursor solution: 2.5 parts by volume of 3-(trimethoxysilyl)propyl methacrylate, 2.5 parts by volume of acetic acid, 5 parts by volume of deionized water and 90 parts by volume of ethanol were mixed and stirred for 1 hour to obtain the precursor solution.

[0078] 2) Preparation of intermediate product: Ceramic particles were placed in the precursor solution and stirred at 70°C for 6 hours. After silanization, the product was collected by centrifugation, washed three times with ethanol, and then dried in an oven to obtain the intermediate product;

[0079] 3) Preparation of modified ceramic particles: 1 part by weight of intermediate product, 9-11 parts by weight of functionalized polymer and trace amount of azobisisobutyronitrile are dispersed in dimethyl sulfoxide solvent. The reaction is carried out at 60°C for 15 hours under nitrogen protection. After the reaction is completed, the particles are washed three times with dimethyl sulfoxide and then dried in an oven to obtain modified ceramic particles.

[0080] 4) Preparation of composite solid electrolyte containing high content of modified ceramic particles: The modified ceramic particles, polymer matrix and lithium salt are dissolved in the corresponding solvent and stirred for 24 hours. The resulting viscous slurry is coated onto a polytetrafluoroethylene plate and dried in an oven to remove the solvent to obtain a composite solid electrolyte membrane.

[0081] This application also provides a solid-state battery, including the aforementioned composite solid-state electrolyte. The solid-state battery prepared with a composite solid-state electrolyte containing a high content of modified ceramic particles exhibits good cycle stability.

[0082] Specifically, solid-state batteries include positive electrode plates, negative electrode plates, and solid electrolytes.

[0083] Specifically, the positive electrode includes a positive current collector and a positive active material layer disposed on the positive current collector. The positive active material layer includes a positive active material, a positive conductive agent, a positive binder, and a solvent. The positive active material is any substance capable of reversibly inserting and deintercalating metal ions such as lithium ions. In some embodiments of this application, the positive active material may be one or more selected from lithium manganese oxide, lithium cobalt oxide, lithium iron phosphate, and ternary positive electrode materials.

[0084] In some embodiments of this application, the negative electrode sheet includes a lithium metal sheet.

[0085] This application also provides an electrical device, including the solid-state battery described above, which serves as the power supply for the electrical device.

[0086] The electrical equipment covered by this application includes, but is not limited to, backup power supplies, motors, electric vehicles, electric motorcycles, electric bicycles, bicycles, power tools, and large household batteries.

[0087] The following description is based on specific embodiments.

[0088] Example 1

[0089] This embodiment provides a method for preparing a composite solid electrolyte, including the following steps:

[0090] 1) Preparation of precursor solution: 2.5 parts by volume of 3-(trimethoxysilyl)propyl methacrylate, 2.5 parts by volume of acetic acid, 5 parts by volume of deionized water and 90 parts by volume of ethanol were mixed and stirred for 1 hour to obtain the precursor solution.

[0091] 2) Preparation of intermediate product: Ceramic particles were placed in the precursor solution and stirred at 70°C for 6 hours. After silanization, the product was collected by centrifugation, washed three times with ethanol, and then dried in an oven to obtain the intermediate product.

[0092] 3) Preparation of modified ceramic particles: 1 part by weight of intermediate product, 10 parts by weight of polyethylene glycol monomethyl ether methacrylate, and a trace amount of azobisisobutyronitrile were dispersed in dimethyl sulfoxide solvent. The mixture was reacted at 60°C for 15 hours under a nitrogen atmosphere. After the reaction, the mixture was washed three times with dimethyl sulfoxide and then dried in an oven to obtain the product.

[0093] 4) Preparation of composite solid electrolyte containing high content of modified ceramic particles: Modified ceramic particles, polyethylene oxide (PEO), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were dissolved in acetonitrile solvent (modified ceramic particles accounted for 60% of the total mass of PEO and LiTFSI, [EO]:[Li + After stirring for 24 hours, the resulting viscous slurry was coated onto a polytetrafluoroethylene plate and dried in an oven to remove acetonitrile, thus obtaining a composite solid electrolyte membrane.

[0094] The battery assembly method in this embodiment includes:

[0095] 1) Preparation of lithium iron phosphate (LiFePO4) cathode: LiFePO4, conductive carbon, and PVDF were mixed and ground in a mass ratio of 80:10:10. The mixture was then dispersed in NMP and stirred overnight. The slurry was coated onto aluminum foil, and the prepared electrode was dried to remove the solvent.

[0096] 2) Battery assembly for impedance testing: The battery assembly uses a 2032 button cell battery case. Starting from the negative electrode case, the spring sheet, stainless steel current collector, prepared composite solid electrolyte, stainless steel current collector, and positive electrode case are placed in sequence.

[0097] 3) Lithium metal symmetric battery assembly: The battery assembly uses a button-type 2032 battery case. Starting from the negative electrode case, the spring sheet, stainless steel current collector, lithium metal sheet, prepared composite solid electrolyte, lithium metal sheet, stainless steel current collector and positive electrode case are placed in sequence.

[0098] 4) Lithium iron phosphate full battery assembly: The battery assembly uses a button-type 2025 battery case. Starting from the negative electrode case, the spring sheet, stainless steel current collector, lithium metal sheet, prepared composite solid electrolyte, LFP positive electrode sheet and positive electrode case are placed in sequence.

[0099] Considering the impact of the battery's internal environment on performance, all battery assembly was carried out in an argon-protected glove box (with water and oxygen levels below 0.01 ppm). In addition, the positive and negative electrode shells, spring sheets, and stainless steel current collectors were all cleaned and dried with ethanol before being placed in the glove box.

[0100] Performance testing methods:

[0101] The surface morphology of the modified ceramic particles was examined using transmission electron microscopy (TEM).

[0102] The surface chemical composition of the modified ceramic particles was detected using X-ray photoelectron spectroscopy (XPS).

[0103] The surface morphology of the prepared composite solid electrolyte membrane was examined using scanning electron microscopy (SEM).

[0104] The mechanical properties of the prepared composite solid electrolyte membrane were tested using a universal material testing instrument. A constant-rate tensile test was performed at a tensile rate of 30 mm / min.

[0105] The temperature-dependent conductivity of the prepared solid composite electrolyte membrane was calculated using AC impedance spectroscopy. The frequency range of the tests was 0.1–10 Hz. 6 The Hz conductivity was tested using a stainless steel (SS) / composite solid electrolyte / stainless steel (SS) structure. The formula for calculating ionic conductivity is as follows:

[0106]

[0107] Where σ is the conductivity (unit: S·cm) -1 L is the thickness of the solid composite electrolyte membrane (unit: cm); R is the impedance of the solid composite electrolyte (unit: Ω); S is the area of ​​the stainless steel current collector (unit: cm²). 2 ).

[0108] The cycling performance of the composite solid electrolyte membrane was investigated using constant current charge-discharge tests. A lithium-ion symmetric battery was used at 0.1 mA / cm². -2 Tested at current density.

[0109] The rate performance, cycle life, discharge specific capacity, and coulombic efficiency of the composite solid electrolyte membrane were investigated through charge-discharge tests. Tests were conducted using Li / LiFePO4 batteries at different rates and within the range of 2.6–4.2 V.

[0110] The test results are as follows:

[0111] Figure 1 The image shows a TEM image of the modified ceramic particles. The surface of the modified ceramic particles has obvious amorphous regions, which are the grafted functionalized polymer layers.

[0112] Figure 2 and Figure 3 The XPS spectra of the modified ceramic particles show characteristic peaks for OC=O (C 1s at 288.9 eV, O 1s at 531.8 eV), Si-O (O 1s at 531.1 eV), and CO (C 1s at 286 eV, O 1s at 532.7 eV) in both the ceramic particles (LLZTO) and the modified LLZTO. This indicates that polyethylene glycol monomethyl ether methacrylate has been successfully grafted onto the LLZTO surface. Simultaneously, characteristic peaks for Li₂CO₃ (C 1s at 289.7 eV, O 1s at 531.5 eV) were observed in the LLZTO particles. However, these peaks were not found in the modified LLZTO, suggesting that the harmful impurity Li₂CO₃ on the LLZTO surface has been eliminated.

[0113] Figure 4 and Figure 5 The image shows a SEM image of the prepared composite solid electrolyte, in which the modified ceramic particles are uniformly distributed.

[0114] Figure 6 The mechanical properties of the prepared composite solid electrolyte are shown in the figure. The tensile strength of the membrane is 2450.73 kPa, the elongation at break is 2015.88%, and the Young's modulus is 125.63 kPa.

[0115] Figure 7 and Figure 8 The electrochemical impedance spectroscopy and Arrhenius plot of the prepared composite solid electrolyte are shown. The figures show that the impedance of the prepared composite solid electrolyte membrane decreases with increasing temperature, while the ionic conductivity increases with increasing temperature. At 30℃, the ionic conductivity is 3.62 × 10⁻⁶. -5 S·cm -1 The ionic conductivity at 60℃ is 1.91 × 10⁻⁶. - 3 S·cm -1 .

[0116] Figure 9 This is a constant current charge-discharge test diagram for a lithium symmetric battery. At 0.1 mA / cm²... -2 At a current density of 1000 mV, the lithium symmetric battery assembled from the prepared composite solid electrolyte membrane can cycle stably for 1200 hours with a polarization potential of only 40 mV.

[0117] Figure 10 and Figure 11 This is a long-cycle test graph for the all-solid-state battery. At 1C, the Li / LiFePO4 battery assembled with the prepared composite solid-state electrolyte membrane exhibits a capacity of 165 mAh·g. -1The initial capacity was maintained at 83% after 250 cycles, and the coulombic efficiency remained stable above 99.5%. The polarization potential remained below 0.1V for 100 cycles and increased only to 0.22V after 250 cycles.

[0118] Figure 12 The figure shows the rate performance of the all-solid-state battery. At rates of 0.2C, 0.3C, 0.5C, 1C, 3C, and 5C, the Li / LiFePO4 battery assembled with the prepared composite solid-state electrolyte membrane provided 169.1 mAh·g⁻¹, respectively. -1 166.5mAh·g -1 165.2 mAh·g -1 162mAh·g -1 156mAh·g -1 133.7mAh·g -1 Specific capacity.

[0119] Example 2

[0120] The composite solid electrolyte was prepared according to the method of Example 1, except that the polymer matrix was replaced with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP). The battery assembly and performance testing methods were the same as in Example 1.

[0121] The test results are as follows:

[0122] Figure 13 The image shows a TEM image of the modified ceramic particles. The surface of the modified particles has obvious amorphous regions, which are the grafted polymer layers.

[0123] Figure 14 and Figure 15 The XPS spectra of the modified ceramic particles show characteristic peaks for OC=O (C 1s at 288.9 eV, O 1s at 531.8 eV), Si-O (O 1s at 531.1 eV), and CO (C 1s at 286 eV, O 1s at 532.7 eV) in both the ceramic particles (LLZTO) and the modified LLZTO. This indicates that polyethylene glycol monomethyl ether methacrylate has been successfully grafted onto the LLZTO surface. Simultaneously, characteristic peaks for Li₂CO₃ (C 1s at 289.7 eV, O 1s at 531.5 eV) were observed in the LLZTO particles. However, these peaks were not found in the modified LLZTO, suggesting that the harmful impurity Li₂CO₃ on the LLZTO surface has been eliminated.

[0124] Figure 16 The image shows a SEM image of the prepared composite solid electrolyte, in which the modified ceramic particles are uniformly distributed.

[0125] Figure 17 The mechanical properties of the prepared composite solid electrolyte are shown in the figure. The tensile strength of the membrane is 362.76 kPa, the elongation at break is 1666.0%, and the Young's modulus is 24.60 kPa.

[0126] Figure 18 and Figure 19 The electrochemical impedance spectroscopy and Arrhenius plot of the prepared composite solid electrolyte are shown. The figures show that the impedance of the prepared composite solid electrolyte membrane decreases with increasing temperature, while the ionic conductivity increases with increasing temperature. At 30℃, the ionic conductivity is 3.69 × 10⁻⁶. -5 S·cm -1 The ionic conductivity at 60℃ is 1.5 × 10⁻⁶. - 3 S·cm -1 .

[0127] Figure 20 This is a constant current charge-discharge test diagram for a lithium symmetric battery. At 0.05 mA / cm²... -2 At a current density of 1000 mV, the lithium symmetric battery assembled from the prepared composite solid electrolyte membrane can cycle stably for 1000 hours with a polarization potential of only 40 mV.

[0128] Figure 21 and Figure 22 This is a long-cycle test result for the all-solid-state battery. At 1C, the Li / LiFePO4 battery assembled with the prepared composite solid-state electrolyte membrane exhibits a capacity of 127 mAh·g. -1 The initial capacity was maintained at 92% after 120 cycles, and the coulombic efficiency remained stable above 99.5%. The polarization potential remained below 0.17V for 50 cycles and increased only to 0.3V after 100 cycles.

[0129] Figure 23 The figure shows the rate performance of the all-solid-state battery. At rates of 0.2C, 0.3C, 0.5C, and 1C, the Li / LiFePO4 battery assembled with the prepared composite solid-state electrolyte membrane provided 156 mAh·g⁻¹, respectively. -1 155mAh·g -1 160mAh·g -1 153mAh·g -1 Specific capacity.

[0130] Example 3

[0131] The composite solid electrolyte was prepared according to the method of Example 2, except that the functionalized polymer was replaced with 10 parts by weight of polymethyl methacrylate. The battery assembly and performance testing methods were the same as in Example 2.

[0132] The test results are as follows:

[0133] Figure 24 The image shows a TEM image of the modified ceramic particles. The surface of the modified particles has obvious amorphous regions, which are the grafted polymer layers.

[0134] Figure 25 The image shows a SEM image of the prepared composite solid electrolyte, in which the modified ceramic particles are uniformly distributed.

[0135] Figure 26 The mechanical properties of the prepared composite solid electrolyte are shown in the figure. The tensile strength of the membrane is 10.7 MPa, the elongation at break is 195.6%, and the Young's modulus is 21.9 MPa.

[0136] Figure 27 The figure shows the Arrhenius plot of the prepared composite solid electrolyte. It can be seen from the figure that the ionic conductivity of the prepared composite solid electrolyte membrane increases with increasing temperature, reaching 1.40 × 10⁻⁶ at 30 °C. -4 S·cm -1 The ionic conductivity at 60℃ is 6.6 × 10⁻⁶. -4 S·cm -1 .

[0137] Figure 28 This is a constant current charge-discharge test diagram for a lithium symmetric battery. At 0.05 mA / cm²... -2 At a current density of [value missing], the lithium symmetric battery assembled from the prepared composite solid electrolyte membrane can cycle stably for 500 hours with a polarization potential of only 0.1V.

[0138] Figure 29 This is a long-cycle test result for the all-solid-state battery. At a rate of 0.2C, the Li / LiFePO4 battery assembled with the prepared composite solid-state electrolyte membrane exhibits a capacity of 160 mAh·g. -1 The initial capacity was maintained at 80% after 100 cycles, and the coulombic efficiency remained stable above 99.5%. The polarization potential remained below 0.1V over 100 cycles.

[0139] Figure 30 The figure shows the rate performance of the all-solid-state battery. At rates of 0.2C, 0.3C, 0.5C, 1C, and 3C, the Li / LiFePO4 battery assembled with the prepared composite solid-state electrolyte membrane provided 164.7 mAh·g⁻¹, respectively. -1 159.5mAh·g -1 92.8mAh·g -1 53.6mAh·g -1 23mAh·g -1 Specific capacity.

[0140] This application improves the interfacial compatibility between the polymer matrix and ceramic particles by grafting and modifying the ceramic particles, thereby enabling a high content of ceramic particles to be uniformly distributed in the polymer matrix, thus giving the composite solid electrolyte excellent electrochemical performance.

[0141] The above provides a detailed description of a composite solid electrolyte, its preparation method, solid battery, and electrical device provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A composite solid-state electrolyte, characterized by, The composite solid-state electrolyte comprises modified ceramic particles, a polymer matrix and a lithium salt, the modified ceramic particles are ceramic particles grafted with a functional polymer, the functional polymer comprises at least one of polyethylene glycol monomethyl ether methacrylate or polymethyl methacrylate, and the ceramic particles comprise a compound with a chemical formula of Li7-xLa3Zr2-xMxO12, wherein 0≤x≤2, and M comprises one or more of Ta, Al, Zr, Sn, Nb, Y or W. The lithium salt comprises lithium bis(trifluoromethanesulfonyl)imide. The mass percentage of the modified ceramic particles is 50% to 70% based on the total mass of the polymer matrix and the lithium salt.

2. The composite solid-state electrolyte of claim 1, wherein, The polymer matrix comprises one or more of polyethylene oxide, polyvinylidene fluoride or poly(vinylidene fluoride-co-hexafluoropropylene).

3. A method for preparing a composite solid-state electrolyte, characterized by, The method comprises: dissolving the modified ceramic particles, the polymer matrix and the lithium salt in a solvent to obtain a slurry by stirring; coating the slurry on a mold, and obtaining the composite solid-state electrolyte after drying and removing the solvent; The modified ceramic particles are ceramic particles grafted with a functional polymer, the functional polymer comprises at least one of polyethylene glycol monomethyl ether methacrylate or polymethyl methacrylate, and the ceramic particles comprise a compound with a chemical formula of Li7-xLa3Zr2-xMxO12, wherein 0≤x≤2, and M comprises one or more of Ta, Al, Zr, Sn, Nb, Y or W.

4. The method of claim 3, wherein the method further comprises, The method for preparing the modified ceramic particles comprises: providing a precursor solution; adding the ceramic particles into the precursor solution, stirring and performing a silanization reaction to obtain an intermediate product; dispersing the intermediate product, the functional polymer and azobisisobutyronitrile in a solvent, and performing a reaction in a nitrogen atmosphere to obtain the modified ceramic particles.

5. The method of claim 4, wherein the composite solid-state electrolyte is prepared by a process comprising: The method for preparing the precursor solution comprises mixing 3(trimethoxysilyl)methyl acrylate, acetic acid, deionized water and ethanol to obtain a precursor solution.

6. The method of claim 4, wherein the composite solid-state electrolyte is prepared by a process comprising: The mass ratio of the intermediate product to the functional polymer is 1:(9-11).

7. A solid state battery, characterized by The composite solid-state electrolyte comprises any one of claims 1-6.

8. An electric device, characterized by The solid-state battery of claim 7 serves as a power supply for the electrical equipment.

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