Preparation method of solid-state electrolyte and solid-state battery

Abstract

This invention proposes a method for preparing a solid electrolyte and a solid-state battery. Through steps such as raw material premixing and grinding, graphene and water ball milling and mixing, membrane material immersion and support, molten salt covering and sintering, and immersion cleaning to desalt and form pores, a porous graphene-modified lithium zirconium chloride solid electrolyte membrane is prepared. This preparation method allows the solid electrolyte to be prepared from ordinary powder, further constructed into a membrane solid electrolyte through membrane material template. Through the synergistic effect of graphene modification and the formation of the porous structure, the conductivity and ion transport performance of the resulting solid electrolyte membrane are improved, thereby providing a better solid electrolyte layer for the battery and increasing the ionic conductivity of the lithium zirconium chloride solid electrolyte.

Description

Technical Field

[0001] This invention relates to the field of solid-state battery technology, and in particular to a method for preparing a solid electrolyte and a solid-state battery. Background Technology

[0002] With the development of new energy technologies, solid-state batteries have received widespread attention because they use solid electrolytes instead of traditional liquid electrolytes. Compared to liquid batteries, solid-state batteries reduce the use of liquid electrolytes in their structure, which can reduce safety risks such as leakage, evaporation, and fire to a certain extent, while also having the potential to improve energy density and range.

[0003] In solid-state batteries, the solid electrolyte membrane plays a crucial role in ion transport, and its performance directly affects the overall charge and discharge performance of the battery. Among these parameters, ionic conductivity is an important indicator for measuring the ion-carrying capacity of a solid electrolyte. The higher the ionic conductivity, the smoother the ion migration within the solid electrolyte, resulting in higher charge and discharge efficiency, lower internal resistance, and easier assurance of rate performance and cycle performance.

[0004] However, existing solid electrolytes still generally suffer from insufficient ion transport capacity in practical applications, which leads to problems such as high internal resistance, significant polarization, and low charge and discharge efficiency in solid batteries during charging and discharging, thus limiting the overall performance of solid batteries.

[0005] Chinese patent CN113948756A discloses a method for preparing a high-performance solid-state battery with lithium zirconium chloride solid electrolyte. The lithium zirconium chloride prepared by this method has low conductivity, does not significantly reduce the internal resistance of the cell or improve long-term cycle performance, and has limited improvement in ionic conductivity, which is not conducive to improving the performance of solid-state batteries. Furthermore, the acetonitrile solution used has a certain degree of toxicity, which is not conducive to large-scale application. Summary of the Invention

[0006] In view of this, it is necessary to provide a method for preparing a solid electrolyte and a battery to solve the problem of low ionic conductivity of the solid electrolyte membrane in solid batteries.

[0007] This application provides a method for preparing a solid electrolyte and a battery. The method for preparing the solid electrolyte includes: Lithium hydroxide monohydrate, zirconium chloride, and lithium chloride were ground to obtain a mixture; Graphene and water were added to the mixture and ball-milled in a protective gas to obtain a precursor mixture. The membrane material is immersed in the precursor mixture and then dried to obtain the dried membrane electrolyte material. The dried membrane electrolyte material is placed in molten salt so that the dried membrane electrolyte material is covered with molten salt on both the top and bottom, and then sintered under a protective gas. The sintered membrane electrolyte material was soaked and cleaned in water and then dried to obtain a porous graphene-modified lithium zirconium chloride solid electrolyte membrane.

[0008] In at least one embodiment of this application, the molar ratio of the lithium hydroxide monohydrate, the zirconium chloride, and the lithium chloride is (1.0-1.5):(1.0-1.5):(1-3).

[0009] In at least one embodiment of this application, the lithium hydroxide monohydrate, the zirconium chloride, and the lithium chloride are ball-milled into powder and mixed for 2-4 hours.

[0010] In at least one embodiment of this application, the membrane material is immersed in the precursor mixture for 2-6 hours. The drying temperature is 50℃-80℃.

[0011] In at least one embodiment of this application, the membrane material is a polyolefin microporous membrane, which includes a PP membrane, a PE membrane, or a PP / PE / PP multilayer composite microporous membrane.

[0012] In at least one embodiment of this application, the sintering temperature is 250℃-400℃ and the sintering time is 3-6h.

[0013] In at least one embodiment of this application, the mass ratio of the dried membrane electrolyte material to the molten salt is 0.5:1 to 2:1.

[0014] In at least one embodiment of this application, the molten salt is one or more of LiNO3, KNO3, NaNO3, NaOH, and KOH.

[0015] In at least one embodiment of this application, the drying temperature after soaking and cleaning is 60℃-80℃. The soaking and cleaning process removes molten salt from the sintered membrane electrolyte material to form a porous structure. The porous graphene-modified lithium zirconium chloride solid electrolyte membrane is a membrane-like solid electrolyte formed by template construction of the membrane material.

[0016] A solid-state battery includes a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer located between the positive electrode active material layer and the negative electrode active material layer, wherein the solid electrolyte layer comprises a porous graphene-modified lithium zirconium chloride solid electrolyte membrane prepared by any one of the above-described preparation methods.

[0017] The solid electrolyte preparation method and solid battery implemented in this embodiment will have at least the following beneficial effects: The solid electrolyte preparation method and solid battery provided above produce a porous graphene-modified lithium zirconium chloride solid electrolyte membrane through steps such as raw material premixing and grinding, graphene and water ball milling and mixing, membrane material immersion and bearing, molten salt covering and sintering, and immersion cleaning and desalting to form pores.

[0018] This preparation method involves preparing a solid electrolyte from ordinary powder, which is then further constructed into a membrane solid electrolyte through template-based membrane material. Through the synergistic effect of graphene modification and porous structure formation, the conductivity and ion transport performance of the resulting solid electrolyte membrane are improved, thereby providing a better solid electrolyte layer for the battery and increasing the ionic conductivity of lithium zirconium chloride solid electrolyte. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] in: Figure 1 This is a flowchart of a method for preparing a solid electrolyte in one embodiment. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In one embodiment of this application, a method for preparing a solid electrolyte and a battery are provided. The method for preparing the solid electrolyte may include the following steps: S101. Lithium hydroxide monohydrate, zirconium chloride and lithium chloride are ground to obtain a mixture.

[0023] Specifically, lithium hydroxide monohydrate, zirconium chloride, and lithium chloride can be weighed according to the preset ratio, and then the weighed raw materials can be added to the grinding equipment for mixing and grinding, so that the raw materials are gradually refined and fully contacted during the grinding process, thereby forming a mixture.

[0024] It should be noted that by pre-grinding lithium hydroxide monohydrate, zirconium chloride, and lithium chloride, the particle size of the raw materials can be reduced, the contact area between the components can be increased, and the lithium source components and zirconium source components can be more fully mixed in the initial stage. This is conducive to the formation of a more uniform precursor system, which can reduce the problem of uneven distribution of local components in subsequent processes and provide a foundation for the formation of the precursor mixture and the final preparation of the lithium zirconium chloride solid electrolyte membrane.

[0025] S102. Graphene and water are added to the mixture and ball-milled in a protective gas to obtain a precursor mixture.

[0026] Specifically, graphene and an appropriate amount of water can be added to the mixture, and the resulting system can be placed in a ball mill and ball milled in a protective gas environment to further homogenize the graphene, water and mixture to form a precursor mixture.

[0027] It should be noted that graphene plays a modifying role in the subsequently formed solid electrolyte in this step, which is beneficial to improving the conductivity of the obtained solid electrolyte membrane; water can be used as a dispersion medium in this step, so that graphene and the components in the aforementioned mixture can be more evenly distributed in the same system, thereby facilitating the formation of a stable precursor mixture.

[0028] Furthermore, ball milling in a protective gas environment reduces the adverse effects of the external environment on the mixing process, thus helping to ensure the stability and uniformity of the precursor system. This also improves the dispersion of the precursor mixture, providing favorable conditions for the subsequent membrane material to support the precursor.

[0029] S103. The membrane material is immersed in the precursor mixture and then dried to obtain the dried membrane electrolyte material.

[0030] Specifically, the pre-prepared diaphragm material can be immersed in the precursor mixture, allowing the precursor mixture to adhere to and penetrate the surface and pore structure of the diaphragm material. After immersion, the diaphragm material is removed and dried to remove moisture from the system, thereby obtaining a dried diaphragm electrolyte material.

[0031] It should be noted that by immersing the membrane material in the precursor mixture, the precursor components can be carried on the surface of the membrane material and in its internal pores, thereby transforming the originally dispersed precursor system into a membrane-like precursor structure attached to the membrane material.

[0032] Furthermore, subsequent drying allows the precursor components to be more stably retained on the membrane material, enabling the obtained intermediate product to form a membrane electrolyte material that is easy to sinter into a membrane, thereby improving the continuity and integrity of the final solid electrolyte membrane.

[0033] S104. The dried membrane electrolyte material is placed in molten salt so that the dried membrane electrolyte material is covered with molten salt on both the top and bottom, and sintered under a protective gas.

[0034] Specifically, molten salt is placed in a sintering container beforehand, and then the dried diaphragm electrolyte material is placed in the molten salt so that both the upper and lower sides of the dried diaphragm electrolyte material are in contact with the molten salt. Subsequently, sintering is performed in a protective gas environment.

[0035] It should be noted that by covering the upper and lower sides of the dried membrane electrolyte material with molten salt, the membrane electrolyte material can be placed in a more uniform working environment during the sintering process, which is beneficial to the transformation of the precursor into the target solid electrolyte structure.

[0036] Furthermore, sintering under a protective gas atmosphere can reduce the influence of external environmental factors on the sintering process, making the sintering process more stable.

[0037] In this step, the molten salt not only participates in the construction of the sintering environment but also provides a foundation for the subsequent formation of porous structures. That is, after the molten salt is removed, pores can be formed in the locations previously occupied by the molten salt. Improving the consistency of material transformation during sintering is beneficial for creating conditions for the subsequent formation of porous graphene-modified lithium zirconium chloride solid electrolyte membranes.

[0038] S105. The sintered membrane electrolyte material is soaked and cleaned in water and then dried to obtain a porous graphene-modified lithium zirconium chloride solid electrolyte membrane.

[0039] Specifically, the sintered diaphragm electrolyte material can be soaked and cleaned in water to allow the molten salt that participated in the sintering process to gradually dissolve and be removed from the material. After that, the cleaned material is dried to remove residual moisture.

[0040] It should be noted that the soaking and cleaning process removes the molten salt from the sintered membrane electrolyte material. The spaces previously occupied by the molten salt are transformed into pores after the molten salt is removed, thus creating a porous structure in the material.

[0041] The porous structure is beneficial for improving the ion migration conditions inside the solid electrolyte membrane; at the same time, graphene modification is beneficial for improving the conductivity of the resulting solid electrolyte membrane.

[0042] The performance of solid electrolyte membranes is optimized through a combination of graphene modification, membrane support, molten salt covering sintering, and immersion cleaning to form pores.

[0043] In summary, this embodiment produces a porous graphene-modified lithium zirconium chloride solid electrolyte membrane through steps such as raw material premixing and grinding, graphene and water ball milling and mixing, membrane material immersion and bearing, molten salt covering and sintering, and immersion cleaning to remove salt and form pores.

[0044] This preparation method involves preparing a solid electrolyte from ordinary powder, which is then further constructed into a membrane solid electrolyte through template-based membrane material. Through the synergistic effect of graphene modification and porous structure formation, the conductivity and ion transport performance of the resulting solid electrolyte membrane are improved, thereby providing a better solid electrolyte layer for the battery and increasing the ionic conductivity of lithium zirconium chloride solid electrolyte.

[0045] It should be noted that the protective gas is either dry argon or nitrogen.

[0046] In at least one embodiment of this application, the molar ratio of the lithium hydroxide monohydrate, the zirconium chloride, and the lithium chloride is (1.0-1.5):(1.0-1.5):(1-3).

[0047] Please refer to Figure 1 In this embodiment, when preparing the raw materials, the amount of lithium hydroxide monohydrate, zirconium chloride and lithium chloride can be calculated according to the preset amount of the target product. Then, the raw materials are weighed according to the molar ratio of lithium hydroxide monohydrate, zirconium chloride and lithium chloride as (1.0-1.5):(1.0-1.5):(1-3). The weighed raw materials are then put into the same mixing system for subsequent grinding and mixing.

[0048] By limiting the molar ratio of lithium hydroxide monohydrate, zirconium chloride, and lithium chloride to the above-mentioned range, a more suitable ratio between the lithium source component and the zirconium source component can be maintained, which is beneficial for the formation of a more uniform precursor system in subsequent processes.

[0049] Limiting the molar ratio of lithium hydroxide monohydrate and zirconium chloride to the range of 1.0-1.5 ensures that the lithium-containing and zirconium-containing components maintain a relatively coordinated ratio during the initial batching stage. This avoids the impact of insufficient dosage of one component on subsequent system formation, as well as the increase of residual components in the system due to excessive dosage of one component.

[0050] Limiting the molar ratio of lithium chloride to 1-3 provides a more sufficient lithium and chlorine-containing environment, which is beneficial to the formation of subsequent lithium zirconium chloride-related systems and improves the flexibility of the composition control of the entire precursor system.

[0051] By limiting the molar ratio of the three raw materials to (1.0-1.5):(1.0-1.5):(1-3), it is easier for each raw material to form a more uniformly distributed mixture during subsequent grinding, ball milling, and mixing processes. This provides a more stable raw material basis for the formation of the precursor mixture and the preparation of the solid electrolyte membrane. This improves the controllability of raw material formulation and enhances the consistency and stability of subsequent preparation processes.

[0052] In summary, by limiting the molar ratio of lithium hydroxide monohydrate, zirconium chloride, and lithium chloride to (1.0-1.5):(1.0-1.5):(1-3), a more suitable component ratio can be established during the raw material preparation stage, thereby improving the uniformity of the precursor system.

[0053] In at least one embodiment of this application, the zirconium chloride is anhydrous zirconium chloride, preferably anhydrous zirconium tetrachloride. Reducing the adverse effects of additional moisture in the raw materials on the formation process of the lithium zirconium chloride system is beneficial to improving the stability of the precursor system composition.

[0054] In at least one embodiment of this application, the graphene is few-layer graphene or graphene nanosheets, preferably few-layer graphene. Further, the number of layers in the few-layer graphene can be 1-10. By using few-layer graphene or graphene nanosheets as a modifying material, it can be more easily dispersed in the precursor mixture and is beneficial for playing a conductive modification role in the subsequently formed solid electrolyte membrane, thereby improving the ion transport performance and overall performance of the obtained lithium zirconium chloride solid electrolyte membrane.

[0055] In at least one embodiment of this application, the milling media is zirconia balls or agate balls, preferably zirconia balls. By using zirconia balls or agate balls as the milling media, a more stable grinding and mixing effect can be provided on the raw materials, and the interference of the milling media on the raw material system can be reduced, thereby improving the stability of the raw material mixing process and the uniformity of the resulting mixed powder.

[0056] In at least one embodiment of this application, the ball-to-material ratio is 5:1-20:1, preferably 8:1-15:1, and more preferably 10:1. By limiting the ball-to-material ratio within the above range, the raw materials can obtain more sufficient collision, tumbling and dispersion during ball milling, which is beneficial to improving the mixing uniformity and particle fineness of each component, and provides a better foundation for the formation of the subsequent precursor mixture.

[0057] In at least one embodiment of this application, the lithium hydroxide monohydrate, the zirconium chloride, and the lithium chloride are ball-milled into powder and mixed for 2-4 hours.

[0058] Please refer to Figure 1 In this embodiment, after weighing lithium hydroxide monohydrate, zirconium chloride and lithium chloride, the above raw materials can be added together into a ball mill, and each raw material can be ground and mixed by ball milling, so that each raw material is gradually refined under the action of ball milling and forms a powder mixture.

[0059] During ball milling, the raw materials achieve more thorough contact and mixing through continuous collision, tumbling, and dispersion, resulting in a more homogeneous powder mixture. Ball milling reduces the particle size of the raw materials and increases the contact area between the components, thus providing more favorable conditions for the formation of subsequent precursor systems.

[0060] Limiting the grinding time to 2-4 hours allows for more thorough mixing and refining of the raw materials during ball milling, thus improving the uniformity of component distribution. If the ball milling time is too short, insufficient contact and mixing between the raw materials can lead to uneven distribution of components in the powder mixture, which is detrimental to the stable formation of the subsequent precursor mixture. Controlling the ball milling time within the 2-4 hour range ensures both effective mixing of the raw materials and process efficiency, making the resulting powder mixture more suitable for further ball milling with graphene and water.

[0061] Graphene comprises 0.1% to 5% of the mass of the mixed powder; in another embodiment, graphene comprises 0.5% to 2% of the mass of the mixed powder. In a specific embodiment, the graphene comprises 1% of the mass of the mixed powder.

[0062] The mass ratio of water to the mixed powder is 2:1 to 8:1. In another embodiment, the mass ratio of water to the mixed powder is 3:1 to 5:1. In a specific embodiment, the mass ratio of water to the mixed powder is 4:1.

[0063] By using ball milling to grind lithium hydroxide monohydrate, zirconium chloride, and lithium chloride into powder and mix them, the uniformity of the raw material premixing stage can be improved, and the consistency of the subsequent preparation process can be enhanced.

[0064] This allows the raw materials to have a better degree of refinement and mixing before entering the subsequent process steps, which is conducive to the formation of a more uniform precursor mixture and provides a basis for finally obtaining a lithium zirconium chloride solid electrolyte membrane with more stable performance.

[0065] By grinding the lithium hydroxide monohydrate, zirconium chloride, and lithium chloride into powder using ball milling and limiting the grinding time to 2-4 hours, better particle refinement and component mixing effects can be achieved in the raw material pretreatment stage, thereby improving the controllability, uniformity, and stability of the subsequent preparation process of lithium zirconium chloride solid electrolyte.

[0066] It should be noted that the grinding speed of the ball mill is 300~500 r / min, and the particle size D50 of the mixed powder after grinding is 1~20 μm.

[0067] Furthermore, it can be selected as 2 to 10 μm.

[0068] In one specific embodiment, the thickness can be selected as approximately 5 μm.

[0069] In at least one embodiment of this application, the membrane material is immersed in the precursor mixture for 2-6 hours, and the drying temperature is 50°C-80°C.

[0070] Please refer to Figure 1 In this embodiment, after the preparation of the precursor mixture is completed, the pre-prepared diaphragm material can be immersed in the precursor mixture, and the immersion time is controlled to be 2-6 hours, so that the components in the precursor mixture can fully adhere to and penetrate into the surface and microporous structure of the diaphragm material.

[0071] After soaking, the membrane material is taken out and dried at a temperature of 50℃-80℃ to remove moisture from the system, thereby obtaining the dried membrane electrolyte material.

[0072] By limiting the soaking time to 2-6 hours, the components in the precursor mixture can form more sufficient contact with the membrane material, which is beneficial to the adhesion and distribution of the precursor on the membrane material.

[0073] When the soaking time is within the range of 2-6 hours, the precursor components can be more fully introduced into the surface of the membrane material and its microporous structure, thereby improving the adhesion of the precursor to the membrane material. On the other hand, it can improve process efficiency and avoid the subsequent processing being affected by improper soaking time settings.

[0074] If the soaking time is too short, the precursor components will not adhere and penetrate sufficiently into the membrane material, which is not conducive to the subsequent formation of a uniform membrane electrolyte material. However, if the soaking time is controlled within the range of 2-6 hours, the precursor components can be more evenly distributed on the membrane material, thus providing a better foundation for subsequent sintering and film formation.

[0075] After soaking, the drying temperature is limited to 50℃-80℃, which allows the soaked membrane material to remove moisture under suitable temperature conditions, thereby ensuring that the precursor components are stably retained on the surface and in the internal pores of the membrane material.

[0076] This helps improve drying efficiency, allowing the diaphragm material to quickly transition from an soaked state to a dry state that facilitates subsequent processing.

[0077] It also helps to maintain the stability of the precursor components carried by the diaphragm material, thereby providing a more stable intermediate product for the subsequent sintering steps.

[0078] By controlling the soaking time of the membrane material in the precursor mixture to 2-6 hours and the drying temperature to 50℃-80℃, the membrane material, as the precursor-loaded substrate, is transformed into a relatively stable dried membrane electrolyte material in a timely manner, thereby providing a foundation for subsequent sintering and film formation and improving the overall performance of the final solid electrolyte membrane.

[0079] It should be noted that the soaking temperature is 20℃-40℃.

[0080] Furthermore, the temperature range can be 25℃-35℃.

[0081] In one specific embodiment, the temperature can be selected as 25°C.

[0082] In at least one embodiment of this application, the membrane material is a polyolefin microporous membrane, which includes a PP membrane, a PE membrane, or a PP / PE / PP multilayer composite microporous membrane.

[0083] Please refer to Figure 1 In this embodiment, before carrying out the precursor mixture carrying step, a polyolefin microporous membrane of appropriate specifications is selected as the membrane material according to the size requirements of the solid electrolyte membrane to be prepared, and the selected membrane material is used as the carrier substrate of the precursor in the subsequent soaking process.

[0084] It should be noted that polyolefin microporous membranes have a microporous structure. When the precursor mixture comes into contact with it, the components in the precursor can adhere to the surface of the membrane material and enter its microporous structure, thereby making the precursor components stably adhere to the membrane material, providing a basis for subsequent drying, sintering and film formation.

[0085] When the membrane material is PP membrane, the better structural support of PP material can be used to make the precursor components more evenly distributed on the surface and inside of the membrane material, which is beneficial to the subsequent formation of a solid electrolyte membrane with better continuity.

[0086] When the membrane material is a PE membrane, the microporous bearing characteristics of the PE membrane can be utilized to make the precursor mixture more easily wetted and distributed in the membrane material, thereby improving the adhesion effect of the precursor on the membrane material.

[0087] When the membrane material is a PP / PE / PP multilayer composite microporous membrane, the characteristics of the multilayer structure can be combined to enable the membrane material to maintain good overall stability and structural integrity while supporting the precursor. This is beneficial for maintaining the membrane morphology during the subsequent sintering process and for the final solid electrolyte membrane to have good continuity.

[0088] By limiting the membrane material to polyolefin microporous membranes and selecting PP membranes, PE membranes, or PP / PE / PP multilayer composite microporous membranes as the carrier substrate, the precursor mixture is transformed from a dispersed state into a membrane-like precursor structure loaded with the membrane material. This provides a foundation for subsequent template-based film formation, thus avoiding the intermediate products from merely exhibiting a loose powder state. This improves the stability of the subsequent sintering film formation process and also helps to enhance the integrity of the final solid electrolyte membrane.

[0089] By setting the membrane material as a polyolefin microporous membrane and using PP membrane, PE membrane or PP / PE / PP multilayer composite microporous membrane as the precursor carrier substrate, a stable adhesion and distribution space can be provided for the precursor components, enabling the subsequent formation of a membrane solid electrolyte through template construction of the membrane material, and improving the structural uniformity and ionic conductivity of the porous graphene-modified lithium zirconium chloride solid electrolyte membrane.

[0090] In at least one embodiment of this application, the sintering temperature is 250℃-400℃ and the sintering time is 3-6h.

[0091] Please refer to Figure 1 In this embodiment, after the dried membrane electrolyte material is placed in molten salt and the dried membrane electrolyte material is covered with molten salt on both the top and bottom, it can be placed in a sintering environment for heating treatment. The sintering temperature is controlled at 250℃-400℃ and the sintering time is controlled at 3-6h.

[0092] It should be noted that limiting the sintering temperature to the range of 250℃-400℃ is beneficial for the transformation of the precursor into the target solid electrolyte structure.

[0093] When the sintering temperature is in the range of 250℃-400℃, the precursor components can obtain sufficient thermal action during the sintering process, thereby improving the overall conversion rate of the material; at the same time, it can also take into account the stability of the overall structure of the membrane electrolyte material, so that the material can maintain a better membrane foundation during the conversion process.

[0094] This facilitates the formation of more uniform intermediate products during the sintering stage and provides conditions for subsequent cleaning, desalting, and the formation of porous structures.

[0095] By limiting the sintering temperature to 250℃-400℃ and the sintering time to 3-6h, sufficient conversion is achieved under suitable conditions, thereby forming a relatively complete lithium zirconium chloride solid electrolyte membrane.

[0096] In at least one embodiment of this application, the mass ratio of the dried membrane electrolyte material to the molten salt is 0.5:1 to 2:1.

[0097] Please refer to Figure 1 In this embodiment, after soaking the membrane material in the precursor mixture and drying it to obtain the dried membrane electrolyte material, the dried membrane electrolyte material is weighed, and then, according to the weighed mass, the corresponding mass of molten salt is weighed according to the mass ratio of the dried membrane electrolyte material to the molten salt of 0.5:1-2:1. Subsequently, the dried membrane electrolyte material is placed in the molten salt so that the dried membrane electrolyte material is covered with the molten salt on both the top and bottom for subsequent sintering treatment.

[0098] It should be noted that by limiting the mass ratio of the dried membrane electrolyte material to the molten salt within the above-mentioned range, the molten salt can form a more sufficient and relatively uniform covering effect on the membrane electrolyte material during the sintering process, thereby providing suitable conditions for the stable transformation of the precursor components.

[0099] When the mass ratio of the dried diaphragm electrolyte material to the molten salt is in the range of 0.5:1 to 2:1, the molten salt can effectively coat the diaphragm electrolyte material during the sintering process and ensure that the molten salt is easily removed during subsequent soaking and cleaning.

[0100] By limiting the mass ratio of the dried membrane electrolyte material to the molten salt to 0.5:1-2:1, it is possible to ensure that the molten salt effectively covers the membrane electrolyte material while taking into account the effects of subsequent sintering conversion and soaking cleaning desalting and pore-forming processes. This is beneficial to obtaining a porous graphene-modified lithium zirconium chloride solid electrolyte membrane with a more uniform structure and more stable performance.

[0101] In at least one embodiment of this application, the molten salt is one or more of LiNO3, KNO3, NaNO3, NaOH, and KOH.

[0102] Please refer to Figure 1In this embodiment, before the sintering step, LiNO3, KNO3, NaNO3, NaOH, and KOH are selected as molten salts according to the preset process conditions and the amount of dried diaphragm electrolyte material, or two or more of them are selected and used in combination. Then, the selected molten salts are added to the upper and lower sides of the dried diaphragm electrolyte material so that the dried diaphragm electrolyte material is covered by molten salts, and then the subsequent sintering process is carried out.

[0103] The dried membrane electrolyte material can be placed in an environment involving molten salt during the sintering process, thereby providing conditions for the transformation of precursor components and the subsequent formation of porous structures.

[0104] When the molten salt is one or more of LiNO3, KNO3, and NaNO3, its molten salt effect during the sintering process can be utilized to enable the dried membrane electrolyte material to obtain a more uniform working environment during the sintering process, thereby improving the consistency of the overall material conversion process.

[0105] When the molten salt is one or more of NaOH and KOH, it can also form a covering effect during the sintering process, so that the membrane electrolyte material can maintain more sufficient molten salt contact conditions under heating, thereby providing a basis for the subsequent formation of a more uniform pore structure.

[0106] The molten salt can be set to one or more of the above-mentioned types, and the molten salt system can be flexibly selected according to actual process requirements.

[0107] Under different implementation conditions, single or composite molten salts can be selected based on the sintering environment, coverage effect, and subsequent cleaning and pore-forming requirements to improve the adaptability of the process.

[0108] This is beneficial for the dried diaphragm electrolyte material to achieve better coverage and function during the sintering process. It is also beneficial for removing molten salt by cleaning after sintering, so that the original molten salt occupies the position to form a porous structure, thereby obtaining a porous solid electrolyte membrane.

[0109] By limiting the molten salt to one or more of LiNO3, KNO3, NaNO3, NaOH, and KOH, the sintering step can be carried out smoothly while providing a basis for subsequent water washing to remove salt and form pores. This is beneficial for forming a porous graphene-modified lithium zirconium chloride solid electrolyte membrane with a more uniform pore distribution, and further improves the structural uniformity and performance of the resulting membrane.

[0110] In at least one embodiment of this application, the drying temperature after soaking and cleaning is 60℃-80℃. The soaking and cleaning process removes molten salt from the sintered membrane electrolyte material to form a porous structure. The porous graphene-modified lithium zirconium chloride solid electrolyte membrane is a membrane-like solid electrolyte formed by template construction of the membrane material.

[0111] Please refer to Figure 1 In this embodiment, after the sintered membrane electrolyte material is soaked and cleaned, the cleaned membrane electrolyte material is taken out and dried at a temperature of 60°C-80°C.

[0112] By controlling the drying temperature within the range of 60℃-80℃, the moisture remaining on the surface and in the pores of the material after soaking and cleaning can be removed, allowing the material to gradually return to a stable state.

[0113] Drying within this temperature range is beneficial for improving drying efficiency, allowing the cleaned diaphragm electrolyte material to be dehydrated more quickly.

[0114] This helps maintain the stability of the overall structure of the material after cleaning, thus providing conditions for finally obtaining a solid electrolyte membrane with a complete structure.

[0115] After the aforementioned steps of soaking the precursor mixture, drying, sintering, cleaning and drying are completed, a membrane solid electrolyte is formed by template construction of the membrane material.

[0116] It helps maintain the overall continuity of the solid electrolyte, making it easier to apply to battery structures. The membrane solid electrolyte formed by template construction of the separator material can also improve the stability and integrity of the material during use, thus making it more suitable for assembly and application as a solid electrolyte layer.

[0117] By immersing and cleaning the sintered membrane electrolyte material to remove molten salt and form a porous structure, followed by drying at 60℃-80℃, a porous graphene-modified lithium zirconium chloride solid electrolyte membrane can be obtained through template-based construction of the membrane material. This process also improves the stability and integrity of the material during use. It facilitates the formation of a more structurally stable membrane solid electrolyte and improves ion transport conditions within the membrane through the porous structure, thereby enhancing the overall performance of the resulting solid electrolyte membrane.

[0118] For example, lithium hydroxide monohydrate, zirconium chloride, and lithium chloride are ground and mixed, graphene and water are added to the mixed powder, and then ball milled and mixed in a protective gas to obtain a precursor mixture.

[0119] The molar ratio of lithium hydroxide monohydrate, zirconium chloride, and lithium chloride is (1.0-1.5):(1.0-1.5):(1-3); the ball milling mixing time is 2-4 hours.

[0120] Immerse the PE diaphragm in the precursor mixture for 2-6 hours. After immersion, dry it at 50-80℃.

[0121] The dried diaphragm electrolyte material is placed in a crucible with molten salt on both the top and bottom. The crucible is then placed in a tube furnace and sintered under a protective gas at a temperature of 250-400℃ for 3-6 hours. The mass ratio of the diaphragm electrolyte material to the molten salt is 0.5:1-2:1. The molten salt can be one or two of LiNO3, KNO3, NaNO3, NaOH, and KOH.

[0122] The sintered membrane electrolyte material was immersed in water for cleaning, and then dried in an oven at 60-80℃ to obtain a porous graphene-modified lithium zirconium chloride solid electrolyte membrane.

[0123] The solid electrolyte is prepared from ordinary powder and further constructed into a membrane solid electrolyte by template of membrane material. Through the synergistic effect of graphene modification and porous structure, the conductivity and ion transport performance of the obtained solid electrolyte membrane are improved, thereby providing a better solid electrolyte layer for the battery and improving the ionic conductivity of lithium zirconium chloride solid electrolyte.

[0124] The lithium zirconium chloride solid electrolyte prepared according to this embodiment has an ionic conductivity of 2.05*10⁻⁶. -3 S / cm.

[0125] Comparative sample 1 was identical to the example sample except for the absence of graphene; all other process conditions were the same, and its ionic conductivity was 1.53*10⁻⁶. - 3 S / cm; Comparative sample 2 only lacked molten salt treatment and subsequent desalting and pore-forming treatment; the remaining process conditions were the same as in the example, and its ionic conductivity was 1.60*10. -3 S / cm.

[0126] Comparative sample 3 uses non-woven filter paper as the support and employs an ethanol / acetonitrile system. It does not use graphene, polyolefin membranes, or molten salt for pore formation, and its ionic conductivity is 1.20*10. -3 S / cm.

[0127] Example 1 This embodiment provides a method for preparing a porous graphene-modified lithium zirconium chloride solid electrolyte membrane. First, the materials are prepared according to a molar ratio of lithium hydroxide monohydrate, zirconium chloride, and lithium chloride of 1.2:1.0:2.0. Specifically, 0.50 g of lithium hydroxide monohydrate, 2.33 g of anhydrous zirconium tetrachloride, and 0.85 g of lithium chloride are weighed. These raw materials are then added to a ball mill and ball-milled at 350 r / min for 2 hours to form a powder mixture. Subsequently, graphene and deionized water (0.04 g of multilayer graphene and 14.72 g of deionized water) are added to the resulting powder mixture, and the mixture is further ball-milled for 1 hour under dry argon protection to obtain a precursor mixture.

[0128] Further, the PE membrane was immersed in the precursor mixture at a temperature controlled at 25°C for 3 hours. After immersion, the PE membrane was removed and dried at 60°C for 2 hours to obtain a dried membrane electrolyte material. Then, the dried membrane electrolyte material was placed in LiNO3 molten salt, ensuring that both the top and bottom of the dried membrane electrolyte material were covered with the molten salt, wherein the mass ratio of the dried membrane electrolyte material to the molten salt was 1:1. Next, it was sintered at 300°C for 4 hours under dry argon protection. After sintering, the sintered membrane electrolyte material was immersed in deionized water to remove the molten salt, and then dried at 70°C for 3 hours to obtain a porous graphene-modified lithium zirconium chloride solid electrolyte membrane.

[0129] In this embodiment, by selecting a PE membrane as the carrier substrate and combining it with graphene modification, molten salt covering sintering, and water washing to remove salt and form pores, a membrane-like solid electrolyte formed by template construction of the membrane material can be obtained. Simultaneously, a relatively uniform porous structure is formed, which is beneficial for improving the ion transport conditions and overall stability of the resulting solid electrolyte membrane. The ionic conductivity is 1.8*10⁻⁶. -3 S / cm.

[0130] Example 2 This embodiment provides a method for preparing a porous graphene-modified lithium zirconium chloride solid electrolyte membrane. First, the raw materials are prepared according to a molar ratio of lithium hydroxide monohydrate, zirconium chloride, and lithium chloride of 1.3:1.2:2.5. Specifically, 0.55 g of lithium hydroxide monohydrate, 2.80 g of anhydrous zirconium tetrachloride, and 1.06 g of lithium chloride are weighed. These raw materials are added to a ball mill and ball-milled at 400 r / min for 3 hours to form a powder mixture. Subsequently, graphene and deionized water (0.06 g of multilayer graphene and 17.64 g of deionized water) are added to the obtained powder mixture, and ball-milling is continued for 1.5 hours under nitrogen protection to obtain a precursor mixture.

[0131] Further, the PP / PE / PP multilayer composite microporous membrane was immersed in the precursor mixture at a temperature controlled at 30°C for 4 hours. After immersion, it was dried at 70°C for 2.5 hours to obtain the dried membrane electrolyte material. Then, the dried membrane electrolyte material was placed in a composite molten salt composed of LiNO3 and KNO3, with a mass ratio of LiNO3 to KNO3 of 1:1 and a mass ratio of the dried membrane electrolyte material to the composite molten salt of 0.8:1, so that the dried membrane electrolyte material was covered with the composite molten salt on both sides. Subsequently, it was sintered at 350°C for 5 hours under nitrogen protection. After sintering, the sintered membrane electrolyte material was immersed and washed in deionized water and dried at 75°C for 4 hours to obtain a porous graphene-modified lithium zirconium chloride solid electrolyte membrane.

[0132] In this embodiment, by selecting a PP / PE / PP multilayer composite microporous membrane as the separator material, the precursor components can be more stably supported in the multilayer microporous structure. Combined with composite molten salt sintering treatment, this improves the consistency of the sintering process and forms a porous membrane with a more uniform pore distribution during subsequent cleaning. This, in turn, improves the structural integrity and performance of the obtained solid electrolyte membrane. The lithium zirconium chloride solid electrolyte membrane prepared in Example 2 has an ionic conductivity of 2.05 × 10⁻⁶. -3 S / cm.

[0133] Example 3 This embodiment provides a method for preparing a porous graphene-modified lithium zirconium chloride solid electrolyte membrane. First, the raw materials are prepared according to a molar ratio of lithium hydroxide monohydrate, zirconium chloride, and lithium chloride of 1.5:1.5:3.0. Specifically, 0.63 g of lithium hydroxide monohydrate, 3.50 g of anhydrous zirconium tetrachloride, and 1.27 g of lithium chloride are weighed. These raw materials are added to a ball mill and ball-milled at 450 r / min for 4 hours to form a fine powder mixture. Subsequently, graphene and deionized water (0.08 g of multilayer graphene and 21.60 g of deionized water) are added to the powder mixture, and ball-milling is continued for 2 hours under dry argon protection to obtain a precursor mixture.

[0134] Further, the PP membrane was immersed in the precursor mixture at a temperature controlled at 35°C for 6 hours. After immersion, it was dried at 80°C for 3 hours to obtain the dried membrane electrolyte material. Then, the dried membrane electrolyte material was placed in NaNO3 molten salt, ensuring it was completely covered from top to bottom, with a mass ratio of the dried membrane electrolyte material to the molten salt of 1.5:1. Subsequently, it was sintered at 380°C for 6 hours under dry argon protection. After sintering, the sintered membrane electrolyte material was immersed and washed in deionized water and dried at 80°C for 4 hours to obtain a porous graphene-modified lithium zirconium chloride solid electrolyte membrane.

[0135] In this embodiment, by increasing the raw material ratio, ball milling time, soaking time, and sintering strength, the precursor components are more fully loaded onto the membrane material, which is beneficial for forming a more structurally complete solid electrolyte membrane. Simultaneously, the porous structure formed after molten salt removal further improves the ion migration channels within the membrane, thereby enhancing the overall performance of the resulting solid electrolyte membrane, with an ionic conductivity of 1.95*10⁻⁶. -3 S / cm.

[0136] The raw materials used in the following experiments are all readily available on the market, and the instrument models involved are as follows: Muffle furnace: Hefei Fishery Thermal Equipment Co., Ltd., tubular furnace, FGL-25 / 11 / 1; Ball mill: Changsha Tianchuang Powder Technology Co., Ltd., planetary ball mill, XQM-1L; Crucible: Zibo Longtai Kiln Industry Technology Co., Ltd., high-temperature resistant ceramic cylindrical crucible, 1000ml; Conductivity tester: Suzhou Jingge Electronics Co., Ltd., ST2643 high-precision insulation resistance tester, high-resistivity material volume surface resistivity measuring instrument 1000V.

[0137] A solid-state battery includes a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer located between the positive electrode active material layer and the negative electrode active material layer, wherein the solid electrolyte layer comprises a porous graphene-modified lithium zirconium chloride solid electrolyte membrane prepared by any one of the above-described preparation methods.

[0138] Please refer to Figure 1 In this embodiment, when assembling a solid-state battery, a positive electrode active material layer and a negative electrode active material layer are first provided. Then, a porous graphene-modified lithium zirconium chloride solid electrolyte membrane obtained by the aforementioned preparation method is disposed between the positive electrode active material layer and the negative electrode active material layer, so that the solid electrolyte membrane exists as a solid electrolyte layer in the battery, thereby forming a complete solid-state battery structure.

[0139] By placing the porous graphene-modified lithium zirconium chloride solid electrolyte membrane between the positive and negative electrode active material layers, an ion transport channel can be formed between the two electrodes, while achieving effective isolation between the positive and negative electrodes, thus meeting the basic operating requirements of solid-state batteries.

[0140] This solid-state electrolyte layer not only possesses a film-like structure, facilitating direct assembly between the positive and negative electrode active material layers, but also leverages the performance advantages brought by graphene modification and a porous structure. Specifically, graphene modification improves the conductivity of the solid-state electrolyte layer, while the porous structure optimizes ion migration pathways, resulting in better ion transport conditions during solid-state battery operation. This contributes to improved charge-discharge efficiency, reduced internal resistance, and enhanced overall battery performance.

[0141] By using the film-like solid electrolyte obtained by the aforementioned preparation method directly as the solid electrolyte layer, the convenience of the solid battery assembly process can be improved. At the same time, it is beneficial to maintain the structural continuity and integrity of the solid electrolyte layer inside the battery, thereby making the solid battery more stable in subsequent use.

[0142] By placing a porous graphene-modified lithium zirconium chloride solid electrolyte membrane, prepared using any of the methods described above, between the positive and negative electrode active material layers as a solid electrolyte layer, a structurally complete solid-state battery can be constructed. This arrangement not only facilitates ion transport and effective isolation between the positive and negative electrodes but also leverages the graphene modification and porous structure of the solid electrolyte membrane to improve the ion transport performance and overall performance of the solid-state battery.

[0143] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A method for preparing a solid electrolyte, characterized in that, The method for preparing the solid electrolyte includes: Lithium hydroxide monohydrate, zirconium chloride, and lithium chloride were ground to obtain a mixture; Graphene and water were added to the mixture and ball-milled in a protective gas to obtain a precursor mixture. The membrane material is immersed in the precursor mixture and then dried to obtain the dried membrane electrolyte material. The dried membrane electrolyte material is placed in molten salt so that the dried membrane electrolyte material is covered with molten salt on both the top and bottom, and then sintered under a protective gas. The sintered membrane electrolyte material was soaked and cleaned in water and then dried to obtain a porous graphene-modified lithium zirconium chloride solid electrolyte membrane.

2. The method for preparing a solid electrolyte according to claim 1, characterized in that, The molar ratio of the lithium hydroxide monohydrate, the zirconium chloride, and the lithium chloride is (1.0-1.5):(1.0-1.5):(1-3).

3. The method for preparing a solid electrolyte according to claim 1, characterized in that, The lithium hydroxide monohydrate, zirconium chloride, and lithium chloride are ball-milled into powder and mixed for 2-4 hours.

4. The method for preparing a solid electrolyte according to claim 1, characterized in that, The membrane material is immersed in the precursor mixture for 2-6 hours. The drying temperature is 50℃-80℃.

5. The method for preparing a solid electrolyte according to claim 1, characterized in that, The membrane material is a polyolefin microporous membrane, which includes PP membrane, PE membrane, or PP / PE / PP multilayer composite microporous membrane.

6. The method for preparing a solid electrolyte according to claim 1, characterized in that, The sintering temperature is 250℃-400℃, and the sintering time is 3-6h.

7. The method for preparing a solid electrolyte according to claim 1, characterized in that, The mass ratio of the dried diaphragm electrolyte material to the molten salt is 0.5:1-2:

1.

8. The method for preparing a solid electrolyte according to claim 1, characterized in that, The molten salt is one or more of LiNO3, KNO3, NaNO3, NaOH, and KOH.

9. The method for preparing a solid electrolyte according to claim 1, characterized in that, The drying temperature after soaking and cleaning is 60℃-80℃. The soaking and cleaning process removes molten salt from the sintered membrane electrolyte material to form a porous structure. The porous graphene-modified lithium zirconium chloride solid electrolyte membrane is a membrane-like solid electrolyte formed by template construction of the membrane material.

10. A solid-state battery, characterized in that, It includes a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer located between the positive electrode active material layer and the negative electrode active material layer, wherein the solid electrolyte layer comprises a porous graphene-modified lithium zirconium chloride solid electrolyte membrane prepared by the preparation method according to any one of claims 1 to 9.

Images