An organic / inorganic composite solid electrolyte thin film material and its preparation method

Abstract

The present invention relates to an organic / inorganic composite solid electrolyte material. The components of the material include: 1) a carbon-doped accordion-shaped LiAl5O8 material; 2) poly(propylene oxide) sulfonyl imide; and 3) lithium bis(trifluoromethane)sulfonyl imide. The mass ratio of the PPCXP, lithium bis(trifluoromethane)sulfonyl imide, and carbon-doped accordion-shaped LiAl5O8 material is 20-60:1-10:1-10. The organic / inorganic composite solid electrolyte material prepared according to the present invention has good flexibility and good interface contact with the electrode material of a lithium battery. The electrolyte film prepared therefrom can effectively improve lithium ion conductivity, promote the migration of lithium ions in the bulk phase and at the interface, and effectively reduce the polarization resistance of the electrode material. It also promotes the uniform deposition of lithium ions, thereby inhibiting the formation of lithium dendrites. Therefore, the lithium battery prepared therefrom has excellent cycle performance and rate performance.

Description

Technical Field

[0001] The present invention relates to the technical field of solid-state lithium battery electrolyte materials, and in particular to an organic / inorganic composite solid electrolyte material, a preparation method thereof, an electrolyte membrane containing the same, and a lithium-ion battery. Background Art

[0002] Future wearable battery systems need to be flexible, wearable, and safe. However, current liquid electrolyte battery systems are prone to electrolyte leakage and are flammable and explosive after collision. Improving battery safety has become an urgent issue. Solid-state lithium batteries use solid electrolytes to replace traditional liquid electrolytes, thereby significantly improving the energy density and safety of batteries. They are one of the most promising energy storage technologies. Although single inorganic solid electrolytes have advantages such as high strength and high ionic conductivity, they have poor flexibility and poor contact between the electrolyte and the negative electrode surface when in contact with the lithium negative electrode. Polymer solid electrolytes have excellent flexibility and processability, but their ionic conductivity at room temperature is relatively low. By doping inorganic fillers into the polymer matrix, organic / inorganic composite solid electrolytes can be prepared, which can significantly improve the room temperature ionic conductivity of the electrolyte and enhance the mechanical strength and electrochemical stability of the composite electrolyte.

[0003] PPC-type polymers have local relaxation and segmental motion in their structures, which facilitates the transport of lithium ions within them. Consequently, PPC-type polymers have high ionic conductivity and can be disposed of in landfills and incineration after use, with the only products being water and carbon dioxide. Therefore, they are a new class of biodegradable, environmentally friendly materials and are considered an ideal organic solid electrolyte. However, compared to liquid electrolytes, the interface wettability of PPC-type polymers as solid electrolytes is poor, resulting in low ionic conductivity and ion mobility. Furthermore, the interface between the lithium negative electrode and the PPC-type polymer electrolyte is unstable and produces side reactions. During the charge and discharge process, changes in the electrode volume cause a surge in interfacial impedance and the growth of lithium dendrites. These factors significantly impact the application of PPC-type polymer solid electrolytes.

[0004] Therefore, solving the interface problem between PPC-type polymers as electrolytes and lithium negative electrodes has become a key issue in achieving the commercialization of PPC electrolytes. Summary of the Invention

[0005] In this patent, we innovatively use metal-organic framework (MOF)-derived active substances to dope a modified PPC and lithium salt blend system (PPCXP-LiTFSI), thereby preparing a new organic / inorganic composite solid electrolyte with good ionic conductivity, high safety, excellent flexibility, and effectively solves the interfacial wettability between the modified PPC and the electrode.

[0006] An object of the present invention is to provide an organic / inorganic composite solid electrolyte material.

[0007] Another object of the present invention is to provide a method for preparing the organic / inorganic composite solid electrolyte film.

[0008] Another object of the present invention is to provide an electrolyte membrane comprising the organic / inorganic composite solid electrolyte material.

[0009] Another object of the present invention is to provide a lithium ion battery comprising the electrolyte membrane.

[0010] According to one aspect of the present invention, an organic / inorganic composite solid electrolyte material is provided, wherein the material components include:

[0011] 1) Carbon-doped accordion-shaped LiAl5O8 material;

[0012] 2)PPCXP material;

[0013] 3) Lithium bis(trifluoromethane)sulfonyl imide;

[0014] The mass ratio of the PPCXP, lithium bis(trifluoromethane)sulfonyl imide and the carbon-doped accordion-shaped LiAl5O8 material is 20-60:1-10:1-10.

[0015] According to another aspect of the present invention, the present invention provides a method for preparing the organic / inorganic composite solid electrolyte material, comprising:

[0016] (1) Al(NO3)3.9H2O, 1,4-naphthalene dicarboxylic acid, and 10 g of deionized water were ultrasonically mixed, sealed in a high-pressure hydrothermal reactor, and reacted at 160-200°C for 12-36 h to obtain an aluminum-based MOF crystal material;

[0017] (2) placing the aluminum-based MOF crystal material in step (1) in a tubular carbonization furnace, and calcining it at 800-1100° C. in an inert atmosphere and a pressure of 20,000-80,000 Pa for 60 to 200 minutes to obtain carbon-doped γ-Al 2 O 3 ;

[0018] (3) mixing the carbon-doped γ-Al2O3 in step (2) with a lithium source in an Al:Li molar ratio of 1:3-5, performing a hydrothermal reaction at 160-200°C for 12-30 hours, cooling, washing, separating, and drying; and sintering the product under the protection of a hydrogen / argon mixed gas at a sintering temperature of 700-1000°C for 1-3 hours to obtain a carbon-doped accordion-shaped LiAl5O8 material;

[0019] The lithium source comprises at least one of lithium nitrate, lithium hexafluorophosphate, lithium phosphate, lithium perchlorate, and lithium carbonate;

[0020] (4) PPCXP (Mn = 50000 ~ 90000 g / mol) is dissolved in 1 to 10 times the weight of NMP (N-methylpyrrolidone) solvent to obtain a solution, and lithium bis(trifluoromethane)sulfonyl imide (LiTFSI, 99.95%, Sigma Aldrich) and the carbon-doped accordion-shaped LiAl5O8 material obtained in step (3) are added so that the mass ratio of PPCXP, lithium bis(trifluoromethane)sulfonyl imide and carbon-doped accordion-shaped LiAl5O8 material is 20 ~ 60: 1 ~ 10: 1 ~ 10, and the mixture is fully dispersed to obtain a uniform electrolyte gel, and then dried to obtain an organic / inorganic composite solid electrolyte material.

[0021] According to another aspect of the present invention, an electrolyte membrane comprising the organic / inorganic composite solid electrolyte material is provided.

[0022] According to another aspect of the present invention, a lithium ion battery including the electrolyte membrane is provided.

[0023] Beneficial effects

[0024] (1) The present invention uses an aluminum-based MOF material derivative, namely a carbon-doped accordion-shaped LiAl5O8, to dope a modified PPC and lithium salt blend system (PPCXP-LiTFSI) to prepare a new organic / inorganic composite solid electrolyte material.

[0025] (2) The accordion-shaped LiAl5O8 doped with carbon is significantly different from the current PPC solid electrolytes. It can promote the migration of lithium ions in the bulk phase and at the electrode interface, effectively reducing the polarization resistance of the electrode material. At the same time, the filling of the accordion-shaped LiAl5O8 doped with carbon material also provides a certain support for the composite electrolyte membrane, increases the mechanical strength, and promotes the uniform deposition of lithium ions, thereby inhibiting the formation of lithium dendrites.

[0026] (3) Another obvious difference is that the present invention is based on industrialized modified PPC material preparation. The solid electrolyte film prepared therefrom has good flexibility and good interface contact with the electrode material, which can effectively improve the lithium ion conductivity and promote the solid lithium battery to have excellent cycle performance and rate performance.

[0027] (4) The preparation method of the present invention is simple and is particularly suitable for the industrial production of modified PPC solid electrolyte materials, and has excellent industrial prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 1 is the XRD pattern of the aluminum-based MOF crystals prepared in the examples of the present invention and the comparative examples;

[0029] Figure 2 This is a low-magnification SEM of the aluminum-based MOF crystal prepared in Example 1 of the present invention;

[0030] Figure 3 This is a high-magnification SEM of the aluminum-based MOF crystal prepared in Example 1 of the present invention.

[0031] Figure 4 This is the XRD pattern of the aluminum-based MOF carbonization product prepared in Example 1 of the present invention.

[0032] Figure 5 is the XRD pattern of the product after lithiation and calcination of the carbonized product in Example 1 of the present invention;

[0033] Figure 6 This is a low-magnification SEM of the carbon-doped accordion-shaped LiAl5O8 material prepared in Example 1 of the present invention.

[0034] Figure 7 This is a high-magnification SEM of the carbon-doped accordion-shaped LiAl5O8 material prepared in Example 1 of the present invention.

[0035] Figure 8 This is the TEM of the carbon-doped accordion-shaped LiAl5O8 material prepared in Example 1 of the present invention.

[0036] Figure 9 This is a photo of the experiment of preparing modified PPCXP according to the present invention. The prepared modified PPCXP has excellent flexibility and stretchability.

[0037] Figure 10 This is the experimental preparation process for preparing modified PPCXP of the present invention.

[0038] Figure 11 The invention discloses a process for preparing a modified PPCXP composite solid electrolyte (LA-PPCXP) film.

[0039] Figure 12 It is a model for preparing the modified PPCXP composite solid electrolyte (LA-PPCXP) of the present invention.

[0040] Figure 13 It is a comparison chart of the cycle performance of solid lithium batteries prepared by the embodiments of the present invention and the comparative embodiments. DETAILED DESCRIPTION

[0041] Unless otherwise specified, all technical and scientific terms used herein have the ordinary meanings understood by those skilled in the art in relation to the present invention. In case of conflict, the definitions in this specification shall prevail. According to one embodiment of the present invention, an organic / inorganic composite solid electrolyte material is provided, wherein the material components include:

[0042] 1) Carbon-doped accordion-shaped LiAl5O8 material;

[0043] 2) Modified PPC (PPCXP);

[0044] 3) Lithium bis(trifluoromethane)sulfonyl imide (LiTFSI)

[0045] Among them, the mass ratio of PPCXP, lithium bis(trifluoromethane)sulfonyl imide and carbon-doped accordion-shaped LiAl5O8 material is 20~60:1~10:1~10.

[0046] The organic / inorganic composite solid electrolyte material containing the above-mentioned specific components and contents can effectively increase the mechanical strength of the composite electrolyte membrane, promote the uniform deposition of lithium ions, inhibit the formation of lithium dendrites, and improve the electrochemical properties of the battery prepared therefrom.

[0047] According to one embodiment of the present invention,

[0048] The carbon content in the carbon-doped accordion-shaped LiAl5O8 material is 20-30%.

[0049] LiAl5O8 containing the above-mentioned carbon doping amount can improve the cycle performance of the lithium solid-state battery prepared therefrom.

[0050] According to one embodiment of the present invention,

[0051] The number average molecular weight of the PPCXP material is 50,000 to 90,000 g / mol, and

[0052] The PPCXP is prepared by the following method:

[0053] Adding phthalic anhydride and propylene oxide into a pre-dissolving kettle to prepare a phthalic anhydride / propylene oxide solution, wherein the molar ratio of phthalic anhydride to propylene oxide in the pre-dissolving kettle is 1:10 to 1:8;

[0054] Phthalic anhydride is added to the polymerization kettle so that the mass ratio of phthalic anhydride in the pre-dissolver to the mass ratio of phthalic anhydride in the polymerization kettle is 2:1, propylene oxide is added, and carbon dioxide is immediately introduced to make the reaction pressure reach 0.7 MPa to 1.3 MPa. The molar ratio of phthalic anhydride to propylene oxide in the pre-dissolver is 1:10 to 1:6;

[0055] The polymerization kettle was heated to 68-72°C at a rate of 0.56-0.6°C / min within 2 hours, and the phthalic anhydride / propylene oxide solution in the pre-dissolved kettle was slowly injected under stirring;

[0056] After the injection is completed, a composite catalyst of bis(triphenylphosphine)ammonium chloride and triethylboron is added, and the reaction is continued for 3h to 4.5h. Then, a terminator is added to the product, and then the PPCXP product is obtained after alcohol precipitation, extrusion, and granulation. The molar ratio of all phthalic anhydride to the composite catalyst is 140:1 to 160:1.

[0057] According to one embodiment of the present invention,

[0058] The PPCXP is prepared by the following method:

[0059] The method comprises the following steps: taking phthalic anhydride, adding 2 / 3 of the weight of the phthalic anhydride into a pre-melting kettle, adding propylene oxide to prepare a phthalic anhydride / propylene oxide solution, and simultaneously adding the remaining 1 / 3 of the weight of the phthalic anhydride into a polymerization kettle, injecting propylene oxide, and injecting carbon dioxide to adjust the reaction pressure to 0.7 MPa to 1.3 MPa before 1 / 3 of the weight of the phthalic anhydride in the polymerization kettle is completely dissolved; heating the polymerization kettle by controlling the heating rate to raise the reaction temperature to 68° C. to 72° C. within 2 hours, and slowly injecting the phthalic anhydride / propylene oxide solution in the pre-melting kettle into the pre-melting kettle; turning on a stirring paddle to stir the reaction; and adding a composite catalyst of bis(triphenylphosphine)ammonium chloride and triethylboron after the injection of the phthalic anhydride / propylene oxide solution is completed.

[0060] The reaction is then continued for 3h to 4.5h, and the glue in the polymerization kettle is transferred to the transfer kettle through a diaphragm metering pump, and a terminator is added to terminate the reaction. The obtained glue is dissolved in dichloromethane and then ethanol is added to precipitate. The precipitate is extruded through a devolatilizer, water-cooled, drawn, dried, and pelletized to obtain the PPCXP product.

[0061] The molar mass ratio of propylene oxide, phthalic anhydride and composite catalyst is 1350:150:1.

[0062] The PPCXP material prepared by the above method has full biodegradability, good stretchability and flexibility.

[0063] According to one embodiment of the present invention, the material is prepared by the following method:

[0064] (1) Al(NO3)3·9H2O, 1,4-naphthalene dicarboxylic acid, and 10 g of deionized water were ultrasonically mixed and sealed in a high-pressure hydrothermal reactor. The mixture was reacted at 160-200°C for 12-36 h to obtain a yellow aluminum-based MOF crystal material.

[0065] (2) placing the aluminum-based MOF crystal material in step (1) in a tubular carbonization furnace, and calcining it at 800-1100° C. in an inert atmosphere and a pressure of 20,000-80,000 Pa for 60 to 200 minutes to obtain carbon-doped γ-Al 2 O 3 ;

[0066] (3) mixing the carbon-doped γ-Al2O3 in step (2) with a lithium source in an Al:Li molar ratio of 1:3-5, performing a hydrothermal reaction at 160-200°C for 12-30 hours, cooling, washing, separating and drying; sintering the product under the protection of a hydrogen / argon mixed gas at a sintering temperature of 700-1000°C for 1-3 hours, thereby preparing a carbon-doped accordion-shaped LiAl5O8 material; the lithium salt comprises: at least one of lithium nitrate, lithium hexafluorophosphate, lithium phosphate, lithium perchlorate, and lithium carbonate;

[0067] (4) dissolving PPCXP having a number average molecular weight of 50,000 to 90,000 g / mol in 1 to 10 times the weight of NMP (N-methylpyrrolidone) solvent to obtain a glue solution, adding lithium bis(trifluoromethane)sulfonyl imide and the carbon-doped accordion-shaped LiAl5O8 material obtained in step (3) so that the mass ratio of PPCXP, lithium bis(trifluoromethane)sulfonyl imide and carbon-doped accordion-shaped LiAl5O8 material is 20 to 60:1 to 10:1 to 10, fully dispersing to obtain a uniform electrolyte glue solution, and drying to obtain an organic / inorganic composite solid electrolyte material.

[0068] By using the above method, a modified PPC solid electrolyte material having good flexibility and conductivity and good interface contact with the electrode material can be prepared.

[0069] According to one embodiment of the present invention, a method for preparing an organic / inorganic composite solid electrolyte thin film material is provided, comprising:

[0070] The electrolyte solution was applied to a frosted glass plate using a doctor blade. A PE film was then quickly spread over it. Once the film was wetted, the electrolyte solution was applied again. Meanwhile, the composite electrolyte membrane was air-dried at 80°C for 15-20 minutes, then transferred to an 80°C forced air drying oven for 12 hours, and then dried again at 100°C under vacuum for 10-12 hours. The resulting organic / inorganic composite solid electrolyte film had a thickness of ~30 μm.

[0071] According to one embodiment of the present invention, an electrolyte membrane is provided, which includes the above-mentioned organic / inorganic composite solid electrolyte thin film material.

[0072] According to one embodiment of the present invention, a lithium ion battery is provided, comprising the above electrolyte membrane.

[0073] In a more specific embodiment of the present invention, the selection of carbonization precursor materials is the key to preparing aluminum-containing metal oxides. In order to obtain a composite material of γ-Al2O3 and conductive carbon, this patent selects an aluminum-containing MOF material as a precursor. The aluminum-based MOF crystal material is placed in a tubular carbonization furnace. In a vacuum inert atmosphere, the temperature of the aluminum-based MOF crystal material is raised to a heating treatment temperature at a heating rate of 5 to 10°C / min for heating carbonization treatment. The pressure of the inert atmosphere is 20,000 to 80,000 Pa, the temperature of the heating carbonization treatment is 800 to 1100°C, and the time of the heating carbonization treatment is 60 to 200 minutes.

[0074] Lithiation treatment:

[0075] In order to further obtain carbon-doped accordion-shaped LiAl5O8 materials, this patent uses lithium salts as lithium sources, such as at least one of lithium nitrate, lithium hexafluorophosphate, lithium phosphate, lithium perchlorate, and lithium carbonate, to perform lithiation treatment on the aluminum-based MOF carbonization product. The specific implementation is as follows: the aluminum-based MOF carbonization product is added to a certain amount of ethanol solution, sealed and then lithium salts (Al:Li molar ratio = 1:3-5) are added, and a hydrothermal reaction is carried out at 180-200°C for 12-20 hours. After cooling, it is washed with ethanol and centrifuged, and placed in a blast drying oven at 80-100°C for drying. Under the protection of a hydrogen / argon mixture, the product is sintered at a sintering temperature of 800-1100°C and a sintering time of 1-4 hours, thereby obtaining a carbon-doped accordion-shaped LiAl5O8 material.

[0076] Solid electrolyte membrane preparation:

[0077] Another object of the present invention is to provide an organic / inorganic solid electrolyte membrane, comprising an organic portion composed of a PPCXP material, and the inorganic material composed of the above-mentioned carbon-doped accordion-shaped LiAl5O8 material.

[0078] The preparation method of the organic part terpolymer PPCXP is as follows:

[0079] A certain amount of phthalic anhydride is taken, 2 / 3 of which is added to a pre-dissolver to prepare a phthalic anhydride / propylene oxide (PO) solution. Meanwhile, the remaining 1 / 3 of the phthalic anhydride is taken and added to a polymerization kettle, and the PO solution is injected. Before the 1 / 3 of the phthalic anhydride is completely dissolved, carbon dioxide (-99.999%) is introduced and the reaction pressure is adjusted to 0.7 MPa-1.3 MPa. The polymerization kettle is heated at a controlled heating rate to raise the reaction temperature to 68-72°C within 2 hours, and the phthalic anhydride / PO solution in the pre-dissolver is slowly injected. A stirring paddle is turned on for stirring during the reaction. After the injection of the phthalic anhydride / PO solution is completed, a composite catalyst of bis(triphenylphosphine)ammonium chloride and triethylboron is added.

[0080] The reaction is continued for 3–4.5 hours, after which the polymerizer solution is transferred to a transfer reactor. A terminator is added to terminate the reaction. The resulting solution is dissolved in dichloromethane and then ethanol is added to precipitate. The precipitate is extruded through a devolatilizer, water-cooled, drawn into a wire, dried, and pelletized to yield the PPCXP product. The molar mass ratio of propylene oxide, phthalic anhydride, and composite catalyst is 1350:150:1, and the molar ratio of bis(triphenylphosphine)ammonium chloride to triethylboron in the composite catalyst is 1:2. A carbon-doped accordion-shaped LiAl₅O₈ material is blended with PPCXP-LiTFSI to prepare a solid electrolyte membrane (LA-PPCXP). The carbon-doped LiAl₅O₈ material provides a more continuous ion transport pathway in the electrolyte system, improving the ionic conductivity of the composite electrolyte. The carbon-doped LiAl₅O₈ material also provides support for the composite electrolyte membrane, increasing its mechanical strength.

[0081] The specific implementation steps are as follows: 2-6g PPCXP (Mn = 50,000-90,000g / mol) is dissolved in 5-30g NMP (N-methylpyrrolidone) solvent to prepare a solution. 0.1-1g lithium bis(trifluoromethane)sulfonyl imide (LiTFSI, 99.95%, Sigma Aldrich) and 0.1-1g carbon-doped accordion-shaped LiAl5O8 material are added to the solution. Stir for 12 hours until fully dispersed, and ultrasonically oscillate for 0.5-1 hour to obtain a uniform electrolyte solution. To enhance the mechanical strength of the electrolyte membrane, a polyethylene (PE) film with a thickness of ~9μm is selected as the support material. First, the first layer of electrolyte solution is applied to a frosted glass plate using a doctor blade. The PE film is then quickly laid and, after soaking, the electrolyte solution is applied again to the PE film. At the same time, the composite electrolyte membrane was dried in air at 80°C for 15 to 20 minutes, then transferred to an 80°C forced air drying oven for drying for 12 hours, and dried again at 100°C under vacuum conditions for 10 to 12 hours, ultimately obtaining an organic / inorganic composite solid electrolyte film with a thickness of ~30 μm.

[0082] The present invention will be further described below with reference to the examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed in the present invention.

[0083] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, and methods in the art. Except for PPCXP biodegradable plastic (produced by China Coal Xuyang Energy Co., Ltd., Mn = 50,000-90,000 g / mol), the remaining chemicals in this experiment are all from MacLean reagent; battery-grade polyethylene diaphragm (PE) diaphragm was purchased from Shenzhen Xuran Electronics Co., Ltd., battery-grade conductive carbon (Super-P) was purchased from Biyuan Electronics Co., Ltd., and lithium sheets and 2025 button battery shells were purchased from Yajun Battery Materials Co., Ltd.

[0084] The TEM used was a JEM-2100 from JEOL, Japan. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) data were obtained using a field emission SU-70 microscope. XRD tests were obtained using a Bruker D8 Advance diffractometer. The automatic coater was purchased from Hefei Kejing Materials Technology Co., Ltd., the argon glove box was purchased from Shanghai Mikaelona (China) Co., Ltd., and the magnetic heating stirrer reactor was purchased from Shanghai Yushen Instrument Co., Ltd. The charge and discharge tests were carried out on a NEWARE (Shenzhen, China) instrument (model 5 V ~ 10 mA).

[0085] The electrochemical performance test method is as follows:

[0086] To test the electrochemical performance of an organic / inorganic solid electrolyte film material (LA-PPCXP), cells were assembled using lithium iron phosphate (LiFePO4) as the cathode material and a lithium sheet as the counter electrode. All cells were assembled in CR2025 battery cases. The assembly process was performed in a nitrogen-filled glove box (O2 <0.1 ppm; H2O <0.1 ppm). A cathode slurry was prepared by adding 70% lithium iron phosphate, 20% conductive carbon black, and 10% polyvinylidene fluoride (PVDF) binder to NMP. The slurry was applied to aluminum foil and dried at 60°C under vacuum for 12 hours. The cathode sheet, LA-PPCXP solid electrolyte film, and lithium anode were assembled in a glove box into 2025-type button cells, labeled LiFePO4 / LA-PPCXP / Li cells. Charge and discharge tests were performed on a NEWARE (Shenzhen, China) instrument (5 V–10 mA).

[0087] Example 1

[0088] A method for preparing a modified PPCXP composite solid electrolyte film comprises the following steps:

[0089] (1) Preparation of precursor raw materials: Preparation of aluminum-based MOF: Weigh 0.375g Al(NO3)3.9H2O, 0.108g 1,4-naphthalene dicarboxylic acid and 10g deionized water, mix them evenly with ultrasound, transfer them into a 23ml reactor, and react in an oven at 180℃ for 24h. Finally, centrifuge and wash the product to obtain a yellow aluminum-based MOF material. Figure 1 XRD analysis shows that the crystals synthesized in this example are consistent with the characteristic peaks of aluminum-based MOF materials, proving the successful synthesis of aluminum-based MOF materials. Figure 2 , Figure 3 ) It can be seen that the aluminum-based MOF material has a unique rod-like structure.

[0090] (2) Carbonization and lithiation treatment: The yellow MOF material is subjected to a one-step carbonization treatment. Under the protection of an inert gas, the aluminum-based MOF crystal material is placed in a tubular carbonization furnace. In a vacuum inert atmosphere, the temperature of the aluminum-based MOF crystal material is raised to a heating treatment temperature at a heating rate of 5°C / min for heating carbonization treatment. The pressure value of the inert atmosphere is 20,000 Pa, the temperature of the heating carbonization treatment is 800°C, and the time of the heating carbonization treatment is 180 min. In order to determine the composition of the carbonized product, the product is subjected to XRD analysis ( Figure 4 ), through analysis it can be seen that the products are mainly the "mantou peak" of amorphous carbon and the characteristic peak of γ-Al2O3.

[0091] In order to further obtain carbon-doped LiAl5O8 material, lithium hexafluorophosphate (LiPF6) was used as a lithium source to perform lithiation treatment on the aluminum-based MOF carbonization product. The specific implementation is as follows: the aluminum-based MOF carbonization product was added to a certain amount of ethanol solution, sealed and then added with lithium salt (Al:Li molar ratio = 1:3), and hydrothermally reacted at 180°C for 15h. After cooling, it was washed with ethanol and centrifuged, and placed in a 100°C blast drying oven for drying. The product was sintered under the protection of hydrogen / argon mixed gas, with a sintering temperature of 800°C and a sintering time of 2h, thereby obtaining a carbon-doped accordion-shaped LiAl5O8 material. In order to determine the composition of the lithiated product, XRD analysis was performed on it ( Figure 5 ), through analysis, it can be seen that the product is mainly the "mantou peak" of amorphous carbon and the characteristic peak of LiAl5O8, proving the successful doping of LiAl5O8. In order to further observe its structure, SEM and TEM analysis were performed on the lithiated product. The morphology is shown in the figure. Figures 6-8 As shown, it can be seen that the composite material is accordion-shaped and maintains the one-dimensional rod-like structure of the aluminum-based MOF material.

[0092] (3) Preparation of solid electrolyte film and electrochemical performance testing:

[0093] The raw materials for PPCXP preparation were prepared according to a molar mass ratio of propylene oxide, phthalic anhydride, and composite catalyst of 1350:150:1, and a molar ratio of bis(triphenylphosphine)ammonium chloride to triethylboron in the composite catalyst of 1:2. Two-thirds of the phthalic anhydride by mass was added to a pre-melting kettle to form a phthalic anhydride / PO solution. Meanwhile, another 1 / 3 of the phthalic anhydride by mass was added to a polymerization kettle, and the PO solution was injected. Until the 1 / 3 of the phthalic anhydride by mass was completely dissolved, carbon dioxide (purity ~99.999%) was introduced, and the reaction pressure was adjusted to 1.1 MPa. The polymerization kettle was heated at a controlled heating rate to 71°C within 2 hours, and the phthalic anhydride / PO solution in the pre-melting kettle was slowly injected. A stirring paddle was turned on during the reaction to provide stirring. After the phthalic anhydride / PO solution was injected, the composite catalyst of bis(triphenylphosphine)ammonium chloride and triethylboron was added.

[0094] The reaction was continued for 4 hours, and the glue in the polymerization kettle was transferred to the transfer kettle, a terminator was added to terminate the reaction, the obtained glue was dissolved with dichloromethane, and then ethanol was added to precipitate the precipitate. The precipitate was extruded through a devolatilizer, water-cooled, drawn, dried, and pelletized to obtain the PPCXP product.

[0095] 4 g of PPCXP (Mn = 50000 g / mol) was dissolved in 20 g of NMP (N-methylpyrrolidone) solvent to prepare a gel solution. 0.7 g of lithium bis(trifluoromethane)sulfonyl imide (LiTFSI, 99.95%, Sigma Aldrich) and 0.7 g of carbon-doped accordion-shaped LiAl5O8 material were added to the solution, stirred for 12 h until fully dispersed, and ultrasonically vibrated for 1 h to obtain a uniform electrolyte gel solution. Figure 9 As shown in the figure, the prepared modified PPCXP electrolyte has excellent stretchability and flexibility. In order to enhance the mechanical strength of the electrolyte membrane, a polyethylene (PE) film with a thickness of ~9 μm was selected as the supporting material. Figure 10 A solid electrolyte film was prepared using the following preparation steps. First, a first layer of electrolyte solution was applied to a frosted glass plate using a doctor blade. A PE film was then quickly laid and, after soaking, the electrolyte solution was applied again to the PE film. Simultaneously, the composite electrolyte membrane was air-dried at 80°C for 20 minutes, then transferred to an 80°C forced air drying oven for 12 hours, and dried a second time at 100°C under vacuum for 12 hours, ultimately resulting in an organic / inorganic composite solid electrolyte film with a thickness of ~30μm.

[0096] The charge and discharge tests were conducted at 25°C on a NEWARE (Shenzhen, China) instrument (model 5V-10mA). The active material loading of the positive electrode material was 5.0mg / cm 2 The current of the charge and discharge test is 0.5C (calculated based on the theoretical specific capacity of the positive electrode lithium iron phosphate 170mAh / g). Figure 12 As shown, after 300 cycles, the specific capacity of the solid battery is 130 mAh / g and the charge and discharge efficiency is 98%.

[0097] Example 2

[0098] The difference between the comparative example and the original example 1 is that, with other steps unchanged, the number average molecular weight of PPCXP is increased to Mn=90,000 g / mol.

[0099] Electrochemical performance test: Figure 12 As shown in the figure, after 300 cycles, the specific capacity of the solid battery is 121 mAh / g, and the charge and discharge efficiency is 97%. It can be seen that when the number average molecular weight Mn of PPCXP is too large, it is not conducive to improving the ion transport and electrochemical performance of the solid-state lithium battery.

[0100] Comparative Example 1

[0101] The difference between the comparative example and the original example 1 is that, with other steps remaining unchanged, no lithiation treatment is performed, and only a composite material of γ-Al2O3 and conductive carbon is used to blend the PPCXP-LiTFSI system and prepare a solid electrolyte film material.

[0102] Electrochemical performance test: Figure 12 As shown in the figure, after 300 cycles, the specific capacity of the solid battery is 112 mAh / g and the charge and discharge efficiency is 97%. It can be seen that the lithiation link is crucial to improving the cycle performance of the solid battery.

[0103] Comparative Example 2

[0104] The difference between the comparative example and the original example 1 is that only PPCXP with a number average molecular weight Mn=50000 g / mol is used as the electrolyte, and no inorganic component is added.

[0105] Electrochemical performance test: Figure 12 As shown in the figure, after 182 cycles, the specific capacity of the solid battery is 89 mAh / g and the charge and discharge efficiency is 96%. It can be seen that using only PPCXP as the electrolyte is not conducive to improving the ion transport and electrochemical performance of the solid lithium battery, and therefore exhibits poor cycle performance.

[0106] The present invention has been described in detail above, but the above embodiments are merely illustrative in nature and are not intended to limit the present invention. In addition, the present invention is not limited by any theory described in the above prior art or invention summary or the following examples.

Claims

1. An organic / inorganic composite solid electrolyte material, the material components comprising: 1) Carbon-doped accordion-shaped LiAl5O8 material; 2) Modified PPC, i.e. PPCXP; 3) Lithium bis(trifluoromethane)sulfonyl imide; Among them, the mass ratio of PPCXP, lithium bis(trifluoromethane)sulfonyl imide and carbon-doped accordion-shaped LiAl5O8 material is 20-60:1-10:1-10, in The number average molecular weight of the PPCXP material is 50,000 to 90,000 g / mol, and The PPCXP is prepared by the following method: Adding phthalic anhydride and propylene oxide into a pre-dissolving kettle to prepare a phthalic anhydride / propylene oxide solution, wherein the molar ratio of phthalic anhydride to propylene oxide in the pre-dissolving kettle is 1:10 to 1:8; Adding phthalic anhydride to a polymerization kettle so that the mass ratio of phthalic anhydride in the pre-dissolution kettle to the mass ratio of phthalic anhydride in the polymerization kettle is 2:1, adding propylene oxide, and immediately charging carbon dioxide to make the reaction pressure reach 0.7 MPa to 1.3 MPa, and the molar ratio of phthalic anhydride to propylene oxide in the polymerization kettle is 1:10 to 1:6; The polymerization kettle was heated to 68-72°C at a rate of 0.56-0.6°C / min within 2 hours, and the phthalic anhydride / propylene oxide solution in the pre-dissolved kettle was slowly injected under stirring; After the injection is completed, a composite catalyst of bis(triphenylphosphine)ammonium chloride and triethylboron is added, and the reaction is continued for 3h to 4.5h. Then, a terminator is added to the product, and then the PPCXP product is obtained after alcohol precipitation, extrusion, and granulation. The molar ratio of all phthalic anhydride to the composite catalyst is 140:1 to 160:

1.

2. The organic / inorganic composite solid electrolyte material according to claim 1, wherein The carbon content in the carbon-doped accordion-shaped LiAl5O8 material is 20% to 30%.

3. The organic / inorganic composite solid electrolyte material according to claim 1, wherein The number average molecular weight of the PPCXP material is 50,000 g / mol.

4. The organic / inorganic composite solid electrolyte material according to claim 1, wherein The PPCXP is prepared by the following method: The method comprises the following steps: taking phthalic anhydride, adding 2 / 3 of the weight of the phthalic anhydride into a pre-dissolving kettle, adding propylene oxide to prepare a phthalic anhydride / propylene oxide solution, and simultaneously adding the remaining 1 / 3 of the weight of the phthalic anhydride into a polymerization kettle, injecting propylene oxide, and injecting carbon dioxide to adjust the reaction pressure to 0.7 MPa to 1.3 MPa before 1 / 3 of the weight of the phthalic anhydride in the polymerization kettle is completely dissolved; heating the polymerization kettle by controlling the heating rate to raise the reaction temperature to 68° C. to 72° C. within 2 hours, and slowly injecting the phthalic anhydride / propylene oxide solution in the pre-dissolving kettle into the polymerization kettle; turning on a stirring paddle to stir the reaction; and adding a composite catalyst of bis(triphenylphosphine)ammonium chloride and triethylboron after the injection of the phthalic anhydride / propylene oxide solution is completed. The reaction is then continued for 3h to 4.5h, and the glue in the polymerization kettle is transferred to the transfer kettle through a diaphragm metering pump, and a terminator is added to terminate the reaction. The obtained glue is dissolved in dichloromethane and then ethanol is added to precipitate. The precipitate is extruded through a devolatilizer, water-cooled, drawn, dried, and pelletized to obtain the PPCXP product. in, The molar mass ratio of propylene oxide, phthalic anhydride and composite catalyst is 1350:150:

1.

5. The organic / inorganic composite solid electrolyte material according to any one of claims 1 to 4, wherein the material is prepared by the following method: (1) Al(NO3)3·9H2O, 1,4-naphthalene dicarboxylic acid, and 10 g of deionized water were ultrasonically mixed and sealed in a high-pressure hydrothermal reactor. The mixture was reacted at 160-200°C for 12-36 h to obtain a yellow aluminum-based MOF crystal material. (2) placing the aluminum-based MOF crystal material in step (1) in a tubular carbonization furnace, and calcining it at 800-1100° C. in an inert atmosphere and a pressure of 20,000-80,000 Pa for 60 to 200 minutes to obtain carbon-doped γ-Al 2 O 3 ; (3) mixing the carbon-doped γ-Al2O3 in step (2) with a lithium source in an Al:Li molar ratio of 1:3-5, performing a hydrothermal reaction at 160-200°C for 12-30 hours, cooling, washing, separating and drying; sintering the product under the protection of a hydrogen / argon mixed gas at a sintering temperature of 700-1000°C for 1-3 hours, thereby preparing a carbon-doped accordion-shaped LiAl5O8 material; the lithium source comprises: At least one of lithium nitrate, lithium hexafluorophosphate, lithium phosphate, lithium perchlorate, and lithium carbonate; (4) dissolving PPCXP having a number average molecular weight of 50,000 to 90,000 g / mol in 1 to 10 times the weight of NMP (N-methylpyrrolidone) solvent to obtain a mixed glue solution, adding lithium bis(trifluoromethane)sulfonyl imide and the carbon-doped accordion-shaped LiAl5O8 material obtained in step (3), wherein the mass ratio of PPCXP, lithium bis(trifluoromethane)sulfonyl imide and the carbon-doped accordion-shaped LiAl5O8 material is 20 to 60:1 to 10:1 to 10, fully dispersing to obtain a uniform electrolyte glue solution, and drying to obtain an organic / inorganic composite solid electrolyte material.

6. A method for preparing an organic / inorganic composite solid electrolyte thin film material, comprising: The electrolyte glue obtained in claim 5 is coated on a frosted glass plate by a scraper, and then a PE film is quickly spread on it. After being soaked, the electrolyte glue is coated on the PE film again; at the same time, the composite electrolyte membrane is dried in air at 80°C for 15 to 20 minutes, and then transferred to an 80°C forced air drying oven for drying for 12 hours, and dried again under vacuum conditions at 100°C for 10 to 12 hours, finally obtaining an organic / inorganic composite solid electrolyte film with a thickness of ~30μm.

7. An electrolyte membrane comprising the organic / inorganic composite solid electrolyte thin film material according to claim 6. A lithium ion battery comprising the electrolyte membrane according to claim 7 .

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