A water-based composite electrolyte membrane and solid-state battery

Abstract

This invention provides an aqueous composite electrolyte membrane and a solid-state battery. The raw materials for preparing the aqueous composite electrolyte membrane include polymer materials, water, modified inorganic solid-state electrolyte materials, and modified lithium salts. The modification method for the modified inorganic solid-state electrolyte materials and modified lithium salts includes: drying the inorganic solid-state electrolyte materials or lithium salts to obtain a dried material; mixing the dried material with an organic ether surface modifier to obtain a mixture; and sintering the mixture to obtain the modified inorganic solid-state electrolyte materials or modified lithium salts. This invention, through modification of the inorganic solid-state electrolyte materials and lithium salts, not only reduces the self-aggregation phenomenon of the inorganic solid-state electrolyte materials but also reduces the water absorption of the lithium salts. This enables the preparation of composite electrolyte membranes in an aqueous system, resulting in aqueous composite electrolyte membranes with advantages such as high ionic conductivity, high mechanical strength, high decomposition voltage, high environmental stability, low cost, and the ability to be mass-produced.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to an aqueous composite electrolyte membrane and a solid-state battery. Background Technology

[0002] Lithium-ion batteries, with their advantages of high operating voltage, high energy density, and long cycle life, are now widely used in vehicle power, energy storage grids, and 3C consumer power applications. To further meet market demand for lithium-ion batteries, it is necessary to develop lithium-ion batteries with higher energy density, higher safety, and longer cycle life. Among these developments, using solid-state electrolytes to completely or partially replace liquid electrolytes to form semi-solid-state, quasi-solid-state, or all-solid-state batteries has become a key research focus.

[0003] PEO-based composite solid electrolytes are widely used in solid-state electrolytes; however, this system still suffers from drawbacks such as low conductivity, high cost, and difficulty in adapting to high-energy cathodes. Therefore, improvements are needed in areas such as the ionic conductivity, electrochemical window, and scalability of composite solid electrolytes.

[0004] Currently, composite electrolyte membranes mainly reduce crystallinity and improve ionic conductivity by introducing inorganic solid electrolyte materials and lithium salts. For example, CN120432622A discloses a PEO-based organic-inorganic composite solid electrolyte membrane and its preparation method. The method first places the required powder in a desiccator for 24 hours to remove water. However, only color-changing silica gel in the desiccator adsorbs water, resulting in weak water absorption by the inorganic solid electrolyte material. Furthermore, due to the internal chemical bonds, the inorganic solid electrolyte material tends to self-aggregate, which severely affects the performance of the composite electrolyte membrane. In addition, it uses DCM (dichloromethane) and anhydrous acetonitrile to dissolve various powders separately, achieving uniform mixing through prolonged stirring. To address the issue of organic solvent volatilization, it employs a combination of static placement in a glove box and drying in a vacuum oven. Therefore, it has significant drawbacks in terms of solvent use and recycling, such as long processing time and high cost.

[0005] In other words, due to the self-aggregation effect of inorganic solid electrolyte materials, uneven dispersion of these materials during the preparation of composite electrolyte membranes leads to excessively low ionic conductivity, significantly affecting the function of the inorganic solid electrolyte materials within the composite electrolyte membrane. Secondly, the polymer electrolytes used in the preparation of composite electrolyte membranes are typically dissolved in organic solvents to facilitate membrane fabrication. However, the use and recycling of toxic and harmful organic solvents raise safety and environmental concerns, and also result in residual organic solvents within the composite electrolyte membrane. These small-molecule organic solvents can easily cause solid-state batteries to fail during high-voltage cycling, reducing cycle performance. Furthermore, the large-scale use of organic liquid solvents also brings environmental problems and increases mass production costs. Moreover, due to the hygroscopic nature of lithium salts, strict control of moisture content during the composite electrolyte membrane preparation process is necessary, further increasing the cost of large-scale production of composite electrolyte membranes.

[0006] Therefore, there is an urgent need to propose an aqueous composite electrolyte membrane with uniform dispersion of inorganic solid electrolyte material and lithium salt. Summary of the Invention

[0007] The purpose of this invention is to provide an aqueous composite electrolyte membrane and a solid-state battery. The aqueous composite electrolyte membrane is modified by using organic ether compounds to modify inorganic solid electrolyte materials and lithium salts. This not only significantly reduces the self-aggregation of inorganic solid electrolyte materials, but also significantly reduces the water absorption of lithium salts and improves their air stability. As a result, the composite electrolyte membrane can be prepared in an aqueous system. The aqueous composite electrolyte membrane has the advantages of high ionic conductivity, high mechanical strength, high decomposition voltage, high environmental stability, low cost, and the ability to be mass-produced.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides an aqueous composite electrolyte membrane, wherein the raw materials for preparing the aqueous composite electrolyte membrane include polymer materials, water, modified inorganic solid electrolyte materials, and modified lithium salts.

[0010] The modified inorganic solid electrolyte material and the modification method of the modified lithium salt include the following steps:

[0011] (1) Dry the inorganic solid electrolyte material or lithium salt to obtain a dried material;

[0012] (2) Mix the dried material described in step (1) with the organic ether surface modifier to obtain a mixture;

[0013] The organic ether surface modifier includes any one or a combination of at least two of the following: polyether siloxane (e.g., polyether-modified heptamethyltrisiloxane), polyoxyethylene ether (e.g., trisiloxane polyoxyethylene ether), or polyethylene glycol alkyl ether.

[0014] (3) Sinter the mixture described in step (2) to obtain a modified inorganic solid electrolyte material or a modified lithium salt.

[0015] It is understood that the water-based composite electrolyte membrane refers to the use of water, rather than organic solvents, as the preparation solvent for the composite electrolyte.

[0016] If the inorganic solid electrolyte material and lithium salt are not surface-treated during the preparation of the composite electrolyte membrane, the two solid powders are prone to self-aggregation in the anhydrous acetonitrile solution, resulting in uneven dispersion and affecting the performance of the composite electrolyte membrane. In addition, lithium salt is hygroscopic and has poor air stability. Furthermore, the use of organic solvents such as acetonitrile in the dispersion process of preparing the composite electrolyte membrane is environmentally unfriendly.

[0017] To address the problems encountered in the preparation of composite electrolyte membranes using inorganic solid electrolyte materials and lithium salts, this invention employs water, modified inorganic solid electrolyte materials, and modified lithium salts to prepare composite electrolyte membranes. This reduces the self-agglomeration of inorganic solid electrolyte materials, promotes their dispersion in aqueous solutions, improves the hydrophobicity of lithium salts, constructs a hydrophobic barrier, ensures the dispersion of lithium salts in aqueous solutions, and reduces the water absorption of lithium salts. Simultaneously, it avoids the use of toxic organic solvents, resulting in an aqueous-based composite electrolyte membrane.

[0018] Specifically, this invention uses organic ether surface modifiers to modify inorganic solid electrolyte materials. Organic ether surface modifiers can be adsorbed on the surface of inorganic solid electrolyte materials, forming steric hindrance, hindering the van der Waals forces between inorganic solid electrolyte material molecules, effectively preventing the re-aggregation of inorganic solid electrolyte materials after dispersion. In addition, the hydrophilic segments of organic ether surface modifiers can also increase their compatibility in polar solvents or with polymers. Polyether segments can also enhance the interfacial bonding between inorganic solid electrolyte materials and polymers, reduce phase separation, and improve ion transport efficiency. In addition, organic ether surface modifiers play the following roles in lithium salt modification: (1) constructing a hydrophobic coating to reduce the water absorption rate of lithium salts; (2) associating with anions in lithium salts to promote lithium salt dissociation and improve ionic conductivity; (3) enhancing interfacial stability; (4) improving thermal stability and electrochemical stability; and (5) acting as a film-forming aid to improve film uniformity. Based on the above modifications to inorganic solid electrolyte materials and lithium salts, the composite electrolyte membrane can completely eliminate the use of toxic and harmful anhydrous acetonitrile, and can be prepared using water. This significantly reduces safety issues in the composite electrolyte production process, avoids solvent recovery problems, and reduces manufacturing costs. The resulting composite electrolyte membrane has advantages such as high ionic conductivity, high mechanical strength, high decomposition voltage, high environmental stability, low cost, and the ability to be mass-produced.

[0019] It is understood that the modification method described in this invention is applicable to both inorganic solid electrolyte materials and lithium salts.

[0020] Preferably, the inorganic solid electrolyte material in step (1) includes an oxide solid electrolyte material, wherein the oxide solid electrolyte material includes LATP (lithium aluminum titanium phosphate), due to the PO4 on the surface of LATP. 3- The negatively charged surfactants, such as polyether siloxanes, can be adsorbed onto the LATP surface, increasing its steric hindrance.

[0021] Preferably, the lithium salt in step (1) includes LiTFSI (lithium bis(trifluoromethanesulfonyl)imide).

[0022] Preferably, the drying temperature in step (1) is 100℃-200℃, for example, 100℃, 120℃, 140℃, 160℃, 180℃ or 200℃, and the time is 4h-24h, for example, 4h, 10h, 15h, 20h or 24h, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0023] Preferably, the drying equipment in step (1) includes a blower drying oven and / or a vacuum drying oven.

[0024] Preferably, the amount of organic ether surface modifier added in step (2) is 0wt%-10wt% of the mass of inorganic solid electrolyte material or lithium salt, but does not include 0wt%. For example, it can be 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt% and 10wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is 2wt%-10wt%.

[0025] If the amount of organic ether surface modifier added in this invention is too small, the modification effect will be reduced. However, if the amount of organic ether surface modifier added is too large, it will hinder ion conduction and significantly reduce ion conductivity.

[0026] Preferably, the mixing time in step (2) is 0 min to 60 min, but not including 0 min. For example, it can be 5 min, 15 min, 25 min, 35 min, 45 min, 55 min or 60 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable. Preferably, it is 20 min to 40 min.

[0027] Preferably, the mixing method in step (2) is dry mixing, and the mixing equipment in step (2) includes any one of the following: agate mortar and pestle, small juicer, Chinese medicine mixing machine, ball mill, V-shaped mixer or high-speed mixer.

[0028] Preferably, the sintering temperature in step (3) is 20℃-200℃, for example, it can be 20℃, 50℃, 100℃, 150℃ or 200℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 120℃-200℃.

[0029] The sintering temperature of this invention affects the modification effect. If the sintering temperature is too low, the organic ether surface modifier cannot crosslink and solidify with the surface of the inorganic solid electrolyte material; if the sintering temperature is too high, there is a risk that the organic ether surface modifier will decompose and fail.

[0030] Preferably, the sintering time in step (3) is 0h-2h, but not including 0h. For example, it can be 0.5h, 1h, 1.5h or 2h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable, preferably 1h-2h.

[0031] Preferably, the heating rate of the sintering in step (3) is 1℃ / min-5℃ / min, for example, it can be 1℃ / min, 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] Preferably, the sintering in step (3) is carried out under a protective atmosphere, such as a nitrogen atmosphere, and the equipment for the sintering in step (3) includes an atmosphere furnace or a muffle furnace.

[0033] Preferably, the particle size D50 of the modified inorganic solid electrolyte material in step (3) is 0.3μm-2μm, for example, it can be 0.3μm, 0.5μm, 1μm, 1.5μm or 2μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the method for preparing the aqueous composite electrolyte membrane includes the following steps:

[0035] The polymer material, water, modified inorganic solid electrolyte material and modified lithium salt are mixed to obtain a mixed slurry. The mixed slurry is coated on a substrate and then dried. After demolding, the water-based composite electrolyte membrane is obtained.

[0036] Preferably, the mixing of the polymer material, water, modified inorganic solid electrolyte material, and modified lithium salt includes the following steps:

[0037] The modified inorganic solid electrolyte material was dispersed in deionized water and then milled to obtain a dispersion of the modified inorganic solid electrolyte material.

[0038] The polymer material is mixed with water to obtain a dispersion of the polymer material. Modified lithium salt is added to the dispersion of the polymer material and stirred to disperse it. Then, a dispersion of modified inorganic solid electrolyte material is added and stirred to disperse it to complete the mixing.

[0039] Preferably, in the process of mixing the polymer material, water, modified inorganic solid electrolyte material and modified lithium salt, the mixing equipment used includes a magnetic stirrer, a cantilever stirrer or a planetary stirrer. The stirring speed at each step is 100 rpm to 1000 rpm, for example, 100 rpm, 500 rpm or 1000 rpm, and the stirring time is 10 min to 60 min, for example, 10 min, 30 min, 50 min or 60 min, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] Preferably, the solid content of the dispersion of the modified inorganic solid electrolyte material is 10wt%-40wt%, for example, it can be 10wt%, 20wt%, 30wt% or 40wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the solid content of the dispersion of the polymer material is 5wt%-15wt%, for example, it can be 5wt%, 7wt%, 9wt%, 11wt%, 13wt% or 15wt%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, the molar ratio of the polymer material to the modified lithium salt is (14-32):1, for example, it can be 14:1, 18:1, 22:1, 26:1 or 32:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, the modified inorganic solid electrolyte material is 10wt%-200wt% of the polymer material, for example, it can be 10wt%, 30wt%, 50wt%, 70wt%, 90wt%, 110wt%, 130wt%, 150wt%, 170wt% or 200wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0044] Preferably, the polymer material includes PEO (polyethylene oxide).

[0045] Preferably, the substrate comprises any one of aluminum foil, tempered glass, polytetrafluoroethylene substrate, polyvinyl chloride substrate, or polyimide substrate.

[0046] In a second aspect, the present invention provides a solid-state battery comprising an aqueous composite electrolyte membrane as described in the first aspect.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] This invention modifies inorganic solid electrolyte materials with organic ether surface modifiers, which significantly reduces the self-aggregation of inorganic solid electrolyte materials, thereby achieving uniform diffusion of inorganic solid electrolyte materials within the composite electrolyte membrane. Simultaneously, the use of organic ether surface modifiers to modify lithium salts significantly reduces their water absorption and improves their air stability. Finally, an aqueous composite electrolyte membrane is prepared using modified inorganic solid electrolyte materials and modified lithium salts. This composite electrolyte membrane possesses numerous advantages, including high ionic conductivity, high mechanical strength, high decomposition voltage, high environmental stability, low cost, and the ability to be applied on a large scale. Attached Figure Description

[0049] Figure 1 The impedance spectra are those of the water-based composite electrolyte membranes described in Examples 1-3 of this invention.

[0050] Figure 2This is a bar chart showing the ionic conductivity of the aqueous composite electrolyte membrane described in Examples 1-3 of this invention. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0052] Example 1

[0053] This embodiment provides a method for modifying inorganic solid electrolyte materials, the method comprising the following steps:

[0054] 30g of LATP powder was weighed and dried in a drying room with a dew point of -40℃ at 200℃ for 6 hours to obtain a dried material. The dried material and 1.5g of polyether-modified heptamethyltrisiloxane (polyether-modified heptamethyltrisiloxane is 5wt% of the mass of LATP powder) were mixed in a dry mixer for 30 minutes. The mixture was then transferred to a crucible and placed in a nitrogen-protected sintering furnace. The temperature was increased to 120℃ at a heating rate of 5℃ / min and sintered for 1.5 hours to obtain a modified inorganic solid electrolyte material with a particle size D50 of 0.467μm.

[0055] This embodiment provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this embodiment, except that LATP powder is replaced by an equal mass of LiTFSI to obtain modified lithium salts.

[0056] This embodiment also provides an aqueous composite electrolyte membrane, the preparation method of which includes the following steps:

[0057] 30g of the modified inorganic solid electrolyte material described in this embodiment was dispersed in 70g of deionized water and finely ground using a sand mill to obtain a dispersion of the modified inorganic solid electrolyte material. 4g of PEO powder was weighed and added to 36g of deionized water, and stirred at 300rpm for 30min using a cantilever stirrer to obtain a dispersion of the polymer material. 1.45g of the modified lithium salt described in this embodiment was weighed and added to the dispersion of the polymer material, and stirred at 300rpm for 30min. Then, 8g of the modified inorganic solid electrolyte material dispersion was weighed and added to the polymer material dispersion, and stirred at 300rpm for 30min to obtain a mixed slurry. In the mixed slurry, the molar ratio of PEO to the modified lithium salt was 18:1, and the modified inorganic solid electrolyte material accounted for 60wt% of the mass of PEO.

[0058] The mixed slurry is coated onto a polytetrafluoroethylene substrate, dried in a vacuum drying oven, and then demolded to obtain the water-based composite electrolyte membrane. The impedance spectrum of the water-based composite electrolyte membrane is shown below. Figure 1 ( Figure 1 As shown in the figure (the horizontal axis represents the real part, and the vertical axis represents the imaginary part), the ionic conductivity histogram is as follows: Figure 2 As shown.

[0059] Example 2

[0060] This embodiment provides a method for modifying inorganic solid electrolyte materials, the method comprising the following steps:

[0061] 30g of LATP powder was weighed and dried in a drying room with a dew point of -40℃ at 200℃ for 6 hours to obtain a dried material. The dried material and 0.6g of polyether-modified heptamethyltrisiloxane (polyether-modified heptamethyltrisiloxane is 2wt% of the mass of LATP powder) were mixed in a small juicer for 20 minutes. The mixture was then transferred to a sagger and placed in a nitrogen-protected sintering furnace. The temperature was increased to 160℃ at a heating rate of 5℃ / min and sintered for 1.5 hours to obtain a modified inorganic solid electrolyte material with a particle size D50 of 0.525μm.

[0062] This embodiment provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this embodiment, except that LATP powder is replaced by an equal mass of LiTFSI to obtain modified lithium salts.

[0063] This embodiment also provides an aqueous composite electrolyte membrane, the preparation method of which includes the following steps:

[0064] 30g of the modified inorganic solid electrolyte material described in this embodiment was dispersed in 70g of deionized water and finely ground using a sand mill to obtain a dispersion of the modified inorganic solid electrolyte material. 4g of PEO powder was weighed and added to 36g of deionized water, and stirred at 300rpm for 30min using a cantilever stirrer to obtain a dispersion of the polymer material. 1.45g of the modified lithium salt described in this embodiment was weighed and added to the dispersion of the polymer material, and stirred at 300rpm for 30min. Then, 8g of the modified inorganic solid electrolyte material dispersion was weighed and added to the polymer material dispersion, and stirred at 300rpm for 30min to obtain a mixed slurry. In the mixed slurry, the molar ratio of PEO to the modified lithium salt was 18:1, and the modified inorganic solid electrolyte material accounted for 60wt% of the mass of PEO.

[0065] The mixed slurry is coated onto a polytetrafluoroethylene substrate, dried in a vacuum drying oven, and then demolded to obtain the water-based composite electrolyte membrane. The impedance spectrum of the water-based composite electrolyte membrane is shown below. Figure 1 ( Figure 1 As shown in the figure (the horizontal axis represents the real part, and the vertical axis represents the imaginary part), the ionic conductivity histogram is as follows: Figure 2 As shown.

[0066] Example 3

[0067] This embodiment provides a method for modifying inorganic solid electrolyte materials, the method comprising the following steps:

[0068] 30g of LATP powder was weighed and dried in a drying room with a dew point of -40℃ at 200℃ for 6 hours to obtain a dried material. The dried material and 3g of polyether-modified heptamethyltrisiloxane (polyether-modified heptamethyltrisiloxane is 10wt% of the mass of LATP powder) were mixed in a small juicer for 40 minutes. The mixture was then transferred to a sagger and placed in a nitrogen-protected sintering furnace. The temperature was increased to 200℃ at a heating rate of 5℃ / min and sintered for 1.5 hours to obtain a modified inorganic solid electrolyte material with a particle size D50 of 0.489μm.

[0069] This embodiment provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this embodiment, except that LATP powder is replaced by an equal mass of LiTFSI to obtain modified lithium salts.

[0070] This embodiment also provides an aqueous composite electrolyte membrane, the preparation method of which includes the following steps:

[0071] 30g of the modified inorganic solid electrolyte material described in this embodiment was dispersed in 70g of deionized water and finely ground using a sand mill to obtain a dispersion of the modified inorganic solid electrolyte material. 4g of PEO powder was weighed and added to 36g of deionized water, and stirred at 300rpm for 30min using a cantilever stirrer to obtain a dispersion of the polymer material. 1.45g of the modified lithium salt described in this embodiment was weighed and added to the dispersion of the polymer material, and stirred at 300rpm for 30min. Then, 8g of the modified inorganic solid electrolyte material dispersion was weighed and added to the polymer material dispersion, and stirred at 300rpm for 30min to obtain a mixed slurry. In the mixed slurry, the molar ratio of PEO to the modified lithium salt was 18:1, and the modified inorganic solid electrolyte material accounted for 60wt% of the mass of PEO.

[0072] The mixed slurry is coated onto a polytetrafluoroethylene substrate, dried in a vacuum drying oven, and then demolded to obtain the water-based composite electrolyte membrane. The impedance spectrum of the water-based composite electrolyte membrane is shown below. Figure 1 ( Figure 1 As shown in the figure (the horizontal axis represents the real part, and the vertical axis represents the imaginary part), the ionic conductivity histogram is as follows: Figure 2 As shown.

[0073] Example 4

[0074] This embodiment provides a method for modifying inorganic solid electrolyte materials, the method comprising the following steps:

[0075] 30g of LATP powder was weighed and dried in a drying room with a dew point of -40℃ at 100℃ for 24h to obtain a dried material. The dried material and 1.5g of polyether-modified heptamethyltrisiloxane (polyether-modified heptamethyltrisiloxane is 5wt% of the mass of LATP powder) were mixed in a small juicer for 30min. The mixture was then transferred to a crucible and placed in a nitrogen-protected sintering furnace. The temperature was increased to 180℃ at a heating rate of 5℃ / min and sintered for 1.5h to obtain a modified inorganic solid electrolyte material with a particle size D50 of 0.513μm.

[0076] This embodiment provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this embodiment, except that LATP powder is replaced by an equal mass of LiTFSI to obtain modified lithium salts.

[0077] This embodiment also provides an aqueous composite electrolyte membrane, the preparation method of which includes the following steps:

[0078] 30g of the modified inorganic solid electrolyte material described in this embodiment was dispersed in 70g of deionized water and finely ground using a sand mill to obtain a dispersion of the modified inorganic solid electrolyte material. 4g of PEO powder was weighed and added to 36g of deionized water, and stirred at 300rpm for 30min using a cantilever stirrer to obtain a dispersion of the polymer material. 1.19g of the modified lithium salt described in this embodiment was weighed and added to the dispersion of the polymer material, and stirred at 300rpm for 30min. Then, 10g of the modified inorganic solid electrolyte material dispersion was weighed and added to the polymer material dispersion, and stirred at 300rpm for 30min to obtain a mixed slurry. In the mixed slurry, the molar ratio of PEO to the modified lithium salt was 22:1, and the modified inorganic solid electrolyte material accounted for 75wt% of the mass of PEO.

[0079] The mixed slurry is scraped onto a polytetrafluoroethylene substrate, dried in a vacuum drying oven, and then demolded to obtain the water-based composite electrolyte membrane.

[0080] Example 5

[0081] This embodiment provides a method for modifying inorganic solid electrolyte materials, the method comprising the following steps:

[0082] 30g of LATP powder was weighed and dried in a drying room with a dew point of -40℃ at 200℃ for 6 hours to obtain a dried material. The dried material was mixed with 0.3g of trisiloxane polyoxyethylene ether (1wt% of the mass of LATP powder) using a small juicer for 30 minutes. The mixture was then transferred to a crucible and placed in a nitrogen-protected sintering furnace. The temperature was increased to 120℃ at a heating rate of 5℃ / min and sintered for 1.5 hours to obtain a modified inorganic solid electrolyte material with a particle size D50 of 0.564μm.

[0083] This embodiment provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this embodiment, except that LATP powder is replaced by an equal mass of LiTFSI to obtain modified lithium salts.

[0084] This embodiment also provides an aqueous composite electrolyte membrane, the preparation method of which includes the following steps:

[0085] 30g of the modified inorganic solid electrolyte material described in this embodiment was dispersed in 70g of deionized water and finely ground using a sand mill to obtain a dispersion of the modified inorganic solid electrolyte material. 4g of PEO powder was weighed and added to 36g of deionized water, and stirred at 300rpm for 30min using a cantilever stirrer to obtain a dispersion of the polymer material. 1.0g of the modified lithium salt described in this embodiment was weighed and added to the dispersion of the polymer material, and stirred at 300rpm for 30min. Then, 9g of the modified inorganic solid electrolyte material dispersion was weighed and added to the polymer material dispersion, and stirred at 300rpm for 30min to obtain a mixed slurry. In the mixed slurry, the molar ratio of PEO to the modified lithium salt was 26:1, and the modified inorganic solid electrolyte material accounted for 67.5wt% of the mass of PEO.

[0086] The mixed slurry is scraped onto a polytetrafluoroethylene substrate, dried in a vacuum drying oven, and then demolded to obtain the water-based composite electrolyte membrane.

[0087] Example 6

[0088] This embodiment provides a method for modifying an inorganic solid electrolyte material. The modification method is the same as in Example 1, except that the amount of polyether siloxane surface modifier is changed so that the polyether siloxane surface modifier is 1 wt% of the mass of LATP powder.

[0089] This embodiment provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this embodiment, except that LATP powder is replaced by an equal mass of LiTFSI to obtain modified lithium salts.

[0090] This embodiment also provides an aqueous composite electrolyte membrane. The preparation method of the aqueous composite electrolyte membrane is the same as that in Embodiment 1, except that it uses the modified inorganic solid electrolyte material and modified lithium salt described in this embodiment.

[0091] Example 7

[0092] This embodiment provides a method for modifying an inorganic solid electrolyte material. The modification method is the same as in Example 1, except that the amount of polyether siloxane surface modifier is changed so that the polyether siloxane surface modifier is 12 wt% of the mass of LATP powder.

[0093] This embodiment provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this embodiment, except that LATP powder is replaced by an equal mass of LiTFSI to obtain modified lithium salts.

[0094] This embodiment also provides an aqueous composite electrolyte membrane. The preparation method of the aqueous composite electrolyte membrane is the same as that in Embodiment 1, except that it uses the modified inorganic solid electrolyte material and modified lithium salt described in this embodiment.

[0095] Example 8

[0096] This embodiment provides a method for modifying an inorganic solid electrolyte material. The modification method is the same as in Embodiment 1, except that the sintering temperature is 100°C.

[0097] This embodiment provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this embodiment, except that LATP powder is replaced by an equal mass of LiTFSI to obtain modified lithium salts.

[0098] This embodiment also provides an aqueous composite electrolyte membrane. The preparation method of the aqueous composite electrolyte membrane is the same as that in Embodiment 1, except that it uses the modified inorganic solid electrolyte material and modified lithium salt described in this embodiment.

[0099] Example 9

[0100] This embodiment provides a method for modifying an inorganic solid electrolyte material. The modification method is the same as that in Embodiment 1, except that the sintering temperature is 250°C.

[0101] This embodiment provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this embodiment, except that LATP powder is replaced by an equal mass of LiTFSI to obtain modified lithium salts.

[0102] This embodiment also provides an aqueous composite electrolyte membrane. The preparation method of the aqueous composite electrolyte membrane is the same as that in Embodiment 1, except that it uses the modified inorganic solid electrolyte material and modified lithium salt described in this embodiment.

[0103] Comparative Example 1

[0104] This comparative example provides a composite electrolyte membrane. The preparation method of the composite electrolyte membrane is the same as that in Example 1, except that the modified inorganic solid electrolyte material is replaced by unmodified LATP, the modified lithium salt is replaced by unmodified LiTFSI, and the water is replaced by anhydrous acetonitrile as the solvent.

[0105] Comparative Example 2

[0106] This comparative example provides a composite electrolyte membrane. The preparation method of the composite electrolyte membrane is the same as that in Example 1, except that the modified inorganic solid electrolyte material is replaced by unmodified LATP and the modified lithium salt is replaced by unmodified LiTFSI, and 1.5g of polyether siloxane surface modifier is added when preparing the dispersion of inorganic solid electrolyte material.

[0107] Comparative Example 3

[0108] This comparative example provides a method for modifying an inorganic solid electrolyte material. The modification method is the same as that in Example 1, except that sintering is not performed.

[0109] This comparative example provides a method for modifying lithium salts. The modification method is the same as the method for modifying inorganic solid electrolyte materials described in this comparative example, except that LATP powder is replaced by LiTFSI in equal mass to obtain modified lithium salts.

[0110] This comparative example also provides an aqueous composite electrolyte membrane. The preparation method of the aqueous composite electrolyte membrane is the same as that of Example 1, except that it uses the modified inorganic solid electrolyte material and modified lithium salt described in this comparative example.

[0111] The composite electrolyte membranes obtained in the above embodiments and comparative examples were assembled into a stainless steel pad symmetrical battery, and then impedance tests were performed to obtain the resistance values. The impedance test spectra of Examples 1-5 are shown below. Figure 1 As shown; the ionic conductivity can be calculated using the following formula σ=L / (R×S), where σ represents the ionic conductivity, R is the resistance value, L is the thickness of the composite electrolyte membrane during the test, and S is the area of ​​the composite electrolyte membrane during the test.

[0112] The test results are shown in Table 1:

[0113] Table 1

[0114]

[0115] As can be seen from Table 1:

[0116] Combining Examples 1-5 Figure 1 and Figure 2 It is evident that the composite electrolyte membrane obtained by this invention possesses a high room temperature ionic conductivity. As shown in Example 1 and Comparative Example 1, if the inorganic solid electrolyte material and lithium salt are not modified, the ionic conductivity of the composite electrolyte membrane will be significantly affected. As shown in Examples 1-5 and Comparative Example 2, even when an organic ether surface modifier is added to the dispersion of the inorganic solid electrolyte material during the preparation of the composite electrolyte membrane, the inorganic solid electrolyte material particles agglomerate first, followed by coating, resulting in excessively large particle sizes that affect ion conduction. Consequently, the ionic conductivity of the resulting composite electrolyte membrane is not as high as that of this invention. As shown in Example 1 and Comparative Example 3, the sintering step in the modification process of this invention can improve the modification effect, thereby further enhancing the room temperature ionic conductivity of the composite electrolyte membrane. As shown in Examples 1 and Examples 6-9, the amount of organic ether surface modifier added and the sintering temperature of this invention affect the modification effect, thus affecting the room temperature ionic conductivity of the composite electrolyte membrane.

[0117] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A water-based composite electrolyte membrane, characterized by, The preparation raw material of the water-based composite electrolyte film comprises a polymer material, water, a modified inorganic solid-state electrolyte material, and a modified lithium salt; The modification method of the modified inorganic solid-state electrolyte material and the modified lithium salt comprises the following steps: (1) drying the inorganic solid-state electrolyte material or the lithium salt to obtain a dried material; In step (1), the inorganic solid-state electrolyte material comprises an oxide solid-state electrolyte material, and the oxide solid-state electrolyte material comprises LATP; in step (1), the lithium salt comprises LiTFSI; (2) mixing the dried material in step (1) and an organic ether surface modifier to obtain a mixed material; The organic ether surface modifier comprises any one or a combination of at least two of polyether siloxane, polyoxyethylene ether, or polyethylene glycol alkyl ether; In step (2), the addition amount of the organic ether surface modifier is 2wt%-10wt% of the mass of the inorganic solid-state electrolyte material or the lithium salt; In step (2), the mixing mode is dry mixing; (3) sintering the mixed material in step (2) to obtain a modified inorganic solid-state electrolyte material or a modified lithium salt; In step (3), the sintering temperature is 120°C-200°C; In step (3), the sintering is performed in a nitrogen atmosphere.

2. The water-based composite electrolyte membrane according to claim 1, wherein In step (1), the drying temperature is 100°C-200°C, and the time is 4h-24h.

3. The water-based composite electrolyte membrane according to claim 2, wherein In step (2), the mixing time is 0min-60min, but 0min is excluded.

4. The water-based composite electrolyte membrane according to claim 3, wherein In step (2), the mixing time is 20min-40min.

5. The water-based composite electrolyte membrane according to claim 1 or 2, wherein In step (3), the sintering time is 0h-2h, but 0h is excluded; And / or, in step (3), the heating rate of the sintering is 1°C / min-5°C / min.

6. The water-based composite electrolyte membrane according to claim 5, wherein In step (3), the sintering time is 1h-2h; And / or, in step (3), the particle size D50 of the modified inorganic solid-state electrolyte material is 0.3μm-2μm.

7. The water-based composite electrolyte membrane according to claim 1, wherein The preparation method of the water-based composite electrolyte film comprises the following steps: Mixing a polymer material, water, a modified inorganic solid-state electrolyte material, and a modified lithium salt to obtain a mixed slurry, coating the mixed slurry on a substrate, and then drying to obtain the water-based composite electrolyte film.

8. The water-based composite electrolyte membrane according to claim 7, wherein The mixing of the polymer material, water, the modified inorganic solid-state electrolyte material, and the modified lithium salt comprises the following steps: Dispersing the modified inorganic solid-state electrolyte material in deionized water and sanding to obtain a dispersion liquid of the modified inorganic solid-state electrolyte material; Mixing the polymer material with water to obtain a dispersion liquid of the polymer material, adding the modified lithium salt to the dispersion liquid of the polymer material for stirring and dispersion, then adding the dispersion liquid of the modified inorganic solid-state electrolyte material for stirring and dispersion, and completing the mixing.

9. The water-based composite electrolyte membrane according to claim 1, wherein The molar ratio of the polymer material to the modified lithium salt is (14-32):1; And / or, the modified inorganic solid-state electrolyte material is 10wt%-200wt% of the mass of the polymer material; And / or, the polymer material comprises PEO.

10. A solid-state battery, characterized by, The solid-state battery comprises the water-based composite electrolyte film according to any one of claims 1-9.

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