A nano-solid-state electrolyte slurry and a preparation method thereof

Abstract

This invention provides a nano-solid electrolyte slurry and its preparation method. The core steps of the preparation method include targeted functionalization modification of bacterial cellulose, functionalization treatment of conductive polymers, and in-situ loading of nano-solid electrolytes. This method, by constructing a highly dispersed and highly conductive integrated composite network structure, simultaneously improves the slurry's dispersion stability, ionic conductivity, and system compatibility, while also considering process feasibility and battery energy density requirements. The prepared nano-solid electrolyte slurry can be directly applied to the blending or coating of positive and negative electrode materials in semi-solid / all-solid lithium batteries, providing a feasible technical solution for the industrialization of all-solid lithium batteries. This invention also provides a nano-solid electrolyte slurry.

Description

Technical Field

[0001] This invention belongs to the field of preparation and application of nano solid electrolyte slurry for semi-solid / all-solid lithium-ion batteries, and specifically relates to a nano solid electrolyte slurry and its preparation method. Background Technology

[0002] With the rapid development of lithium-ion batteries towards semi-solid and all-solid-state technologies, constructing an integrated electrode-electrolyte composite structure has become a core technological path to improve battery energy density and enhance interfacial contact and ion transport efficiency. The core of this approach is to blend or coat solid electrolyte powder onto the surface of the positive and negative electrode active materials, establishing a continuous ion conduction network within the electrode to compensate for the inherent solid-solid interface impedance problem between the electrode and the independent solid electrolyte layer. The key to achieving efficient blending and coating of solid electrolyte powder lies in preparing a solid electrolyte slurry adapted to the electrode slurry system. Furthermore, to ensure high battery energy density, it is necessary to reduce the amount of solid electrolyte added while using nanoscale powders to increase the specific surface area, achieving a more uniform distribution and coating effect. This places stringent and mutually restrictive performance requirements on the solid electrolyte slurry, including high compatibility, suitable rheological properties, and high ionic conductivity preservation.

[0003] Existing solid electrolyte slurry technologies are mostly optimized for applications such as independent solid electrolyte thin film preparation and diaphragm coating. However, their direct application to electrode blending or coating presents significant compatibility issues. Slurries designed for film formation often contain specific and high amounts of binders, which can easily cause system conflicts when coexisting with the electrode's own binders, damaging the electrode's mechanical strength. Slurries designed for high ionic conductivity either have stringent requirements for solvent purity or poor chemical stability. When mixed with electrode slurries containing multiple functional components, uncontrollable side reactions can easily occur, leading to "passivation" of the solid electrolyte surface and loss of ion transport function. Meanwhile, while nanoscale solid electrolyte powders possess high ionic conductivity, they are prone to agglomeration and sedimentation, resulting in poor slurry uniformity. Existing technologies only offer simple adaptations to general-purpose solid electrolyte slurries or traditional electrode slurries, making it difficult to achieve the optimal balance between process feasibility and electrochemical performance.

[0004] In summary, developing a nano-solid electrolyte slurry that is suitable for electrode mixing and coating scenarios, enhances the composite effect of bacterial cellulose functionalization and conductive polymers, constructs a highly dispersed and highly conductive integrated network, and simultaneously possesses excellent dispersion stability, high ionic conductivity, and high compatibility with existing electrode slurry systems, has become a critical technical bottleneck to be solved in the industrialization of all-solid-state lithium batteries. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a method for preparing a nano-solid electrolyte slurry, which solves multiple technical difficulties encountered in the industrialization of all-solid-state lithium batteries when using existing nano-solid electrolyte slurries for electrode mixing or coating.

[0006] The present invention also provides a nano-solid electrolyte slurry.

[0007] The first aspect of the present invention provides a method for preparing a nano-solid electrolyte slurry, comprising the following steps: S1: Targeted functionalization modification of bacterial cellulose: Introducing organic functional groups to modify the surface of bacterial cellulose to obtain functionalized bacterial cellulose; S2: Functionalization of conductive polymers: Functional modification of conductive polymers to obtain functionalized conductive polymers; S3: In-situ loading of nano-solid electrolyte: In-situ loading of nano-solid electrolyte powder into a composite network matrix formed by the bacterial cellulose and the functionalized conductive polymer.

[0008] The method for preparing nano-solid electrolyte slurry of the present invention has at least the following beneficial effects: Bacterial cellulose, as a natural polymer material, possesses a unique three-dimensional nanofiber network structure. In its gel state, it provides ample dispersion space, making it an ideal stable support for nano-solid electrolyte powders. However, its own conductivity is extremely poor, and its surface hydroxyl groups are uniformly distributed, resulting in insufficient interfacial compatibility with conductive polymers such as polypyrrole and polyaniline. Direct composite formation easily leads to phase separation, failing to form an efficient conductive pathway. In existing technologies, the composite of bacterial cellulose and conductive polymers mostly relies on physical mixing or simple surface modification, without designing targeted functionalization strategies for its three-dimensional network structure. This results in uneven dispersion of conductive polymers, weak interfacial bonding, and difficulty in simultaneously achieving high dispersion stability and high conductivity in the slurry.

[0009] The preparation method of this invention, relying on targeted functionalization modification of bacterial cellulose, functionalization treatment of conductive polymers, and in-situ loading of nano-solid electrolytes, achieves multi-dimensional performance improvement and process optimization. Specifically: By introducing epoxide and amine groups into bacterial cellulose for targeted functionalization modification, its three-dimensional nanofiber network structure is preserved while endowing it with stronger interfacial bonding and dispersion loading capabilities, providing a stable three-dimensional dispersion space for nano-solid electrolyte powders. Combined with the in-situ loading method of nano-solid electrolytes, the powder is uniformly embedded in the network matrix, effectively suppressing the problems of nanoparticle agglomeration and sedimentation. This allows the slurry to maintain the stability of powder particle size even after long-term storage, significantly reducing the sedimentation rate and solving the technical pain point of poor uniformity in existing solid electrolyte slurries.

[0010] Furthermore, functionalization of the conductive polymer significantly improves its interfacial compatibility with functionalized bacterial cellulose. The two can form a cross-linked composite network through epoxy-amine and polydopamine-amine reactions, constructing a continuous and efficient conductive pathway. Combined with in-situ loading technology, this preserves the high ionic conductivity of the nano-solid electrolyte while preventing passivation of the powder surface due to side reactions, thus greatly improving the ionic conductivity of the cured slurry film. This solves the problem of insufficient conductivity caused by uneven dispersion of conductive polymers and weak interfacial bonding in traditional composite methods.

[0011] The composite network matrix formed by the preparation method of the present invention does not require additional high-volume special binders, does not conflict with the electrode's own binder system, does not affect the mechanical strength of the electrode, and does not require extremely high-purity solvents during the preparation process. The slurry has excellent chemical stability and does not cause uncontrollable side reactions when blended with electrode slurries containing multiple functional components. It can be directly adapted to the process requirements of electrode blending and coating, making up for the poor adaptability of existing solid electrolyte slurries in electrode application scenarios.

[0012] The composite network formed by modified bacterial cellulose and functionalized conductive polymers can achieve efficient dispersion and stable loading of nano-solid electrolyte powders with low addition amounts, without increasing the mixing ratio of solid electrolytes. This ensures a high proportion of positive and negative electrode active materials in the electrodes, meeting the design requirements of high energy density batteries. Furthermore, the entire preparation process is controllable and the parameters are easily achievable. The modification, composite, and in-situ loading methods used are all suitable for industrial production processes, solving the problem of balancing process feasibility and electrochemical performance that is difficult to achieve in existing technologies.

[0013] In the preparation method of this invention, the core carrier is bacterial cellulose, a natural polymer material. The raw material is green and environmentally friendly. The preparation process uses water or conventional organic solvents as the dispersion medium, and no harmful additives or by-products are generated. Compared with the traditional solid electrolyte slurry preparation process, it is more in line with the environmental protection development trend of green chemical industry and lithium battery industry.

[0014] In summary, the method of this invention simultaneously improves the dispersion stability, ionic conductivity, and system compatibility of the slurry by constructing a highly dispersed and highly conductive integrated composite network structure, while taking into account both process feasibility and battery energy density requirements. The prepared nano-solid electrolyte slurry can be directly applied to the mixing or coating of positive and negative electrode materials for semi-solid / all-solid lithium batteries, providing a feasible technical solution for the industrialization of all-solid lithium batteries.

[0015] According to some embodiments of the present invention, the organic functional group includes an amino group or an epoxy group.

[0016] According to some embodiments of the present invention, in step S1, the method for surface modification of bacterial cellulose by introducing organic functional groups includes: stirring a bacterial cellulose wet gel containing 80-95 wt% water at a speed of 3000-9000 rpm for 10-60 min, then adding 0.5-5 times its mass of deionized water, continuing stirring for 5-60 min to obtain a suspension, adding a modifier containing the said organic functional groups, heating to 30-100℃, stirring at a speed of 300-1000 rpm for 3-5 h, and ultrasonically dispersing for 5 min every 30 min during stirring to facilitate uniform modification, then centrifuging (speed can be 8000 r / min, time can be 10 min), washing 2-5 times with deionized water, and drying in a freeze dryer at -30--60℃ for 10-30 h to obtain functionalized bacterial cellulose. The obtained functionalized bacterial cellulose has a three-dimensional network structure and contains epoxy-amine groups on its surface.

[0017] According to some embodiments of the present invention, in step S2, the conductive polymer is functionalized by means of: dispersing the conductive polymer in 10-50 times its mass of deionized water, ultrasonically dispersing for 30 min to obtain a suspension, then adding 0.5-10 wt% of dopamine hydrochloride of the total weight of the polymer conductive material, stirring at 100-1000 rpm at 30-80°C for 2-10 h, centrifuging and washing, and vacuum drying to obtain the dried polydopamine-modified functionalized conductive polymer material.

[0018] According to some embodiments of the present invention, the modifier containing the said organic functional groups includes trimethoxysilane (0.5-10 wt% of dry bacterial cellulose) and ethylenediamine (0.5-10 wt% of dry bacterial cellulose).

[0019] According to some embodiments of the present invention, the conductive polymer includes at least one of polypyrrole (PPy), polyaniline (PANI), and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate (PEDOT-PSS).

[0020] According to some embodiments of the present invention, the functionalized reagent includes dopamine hydrochloride.

[0021] According to some embodiments of the present invention, the nano-solid electrolyte powder includes oxide nano-solid electrolyte powder, sulfide nano-solid electrolyte powder, or halide nano-solid electrolyte powder.

[0022] According to some embodiments of the present invention, the oxide nanosolid electrolyte powder includes LLZO or LATP.

[0023] According to some embodiments of the present invention, the sulfide nanosolid electrolyte powder includes Li3PS4 or Li6PS5Cl.

[0024] According to some embodiments of the present invention, the halide nanosolid electrolyte powder includes Li3InCl6 or Li2ZrCl6.

[0025] According to some embodiments of the present invention, the particle size D50 of the nano-solid electrolyte powder is 20-200 nm.

[0026] According to some embodiments of the present invention, in step S3, the nano-solid electrolyte powder is in situ loaded into a composite network matrix formed by the bacterial cellulose and the functionalized conductive polymer, the step comprising: The functionalized bacterial cellulose and functionalized conductive polymer are added to the solvent and dispersed to form a uniform dispersion. A crosslinking agent is added, and the mixture is heated and stirred to allow the functionalized bacterial cellulose and functionalized conductive polymer to react and form a crosslinked composite network matrix. A ceramic slurry dispersant is added to the crosslinked composite network matrix, followed by the nano-solid electrolyte powder. The mixture is stirred at 100-500 rpm for 1-3 hours to load the nano-solid electrolyte powder into the network. Subsequently, the mixture is dispersed at 8000-15000 rpm for 1-5 hours to ensure that the nano-solid electrolyte powder is uniformly embedded in the composite network. Finally, the mixture is degassed in a vacuum.

[0027] According to some embodiments of the present invention, the solvent includes deionized water or N-methylpyrrolidone.

[0028] According to some embodiments of the present invention, the crosslinking agent comprises hexamethylene diisocyanate.

[0029] According to some embodiments of the present invention, in step S3, the nano-solid electrolyte powder is in situ loaded into a composite network matrix formed by the bacterial cellulose and the functionalized conductive polymer. This step may include: Add 0.5-5 parts of functionalized bacterial cellulose powder and 0.05-0.5 parts of functionalized conductive polymer to 50 parts of deionized water or anhydrous N-methylpyrrolidone (NMP), ultrasonically disperse for 10-60 min, then stir at 100-1000 rpm for 1-3 h to form a uniform dispersion. Add 0.1-1 parts of crosslinking agent hexamethylene diisocyanate (HDI), heat to 30-90℃ and stir for 2-6 h to allow bacterial cellulose and carbon materials to form a crosslinked composite network through epoxy-amine group reaction and polydopamine-amine group reaction. Add 0.1-2 parts of a commonly used ceramic slurry dispersant (such as polypyrrolidone, polyacrylamide, etc.) to the composite network matrix and stir for 30 minutes. Then, slowly add 20-150 parts of nano-solid electrolyte powder. After complete addition, stir at 100-500 rpm for 1-3 hours to initially load the powder into the network. Subsequently, disperse the powder using a high-shear disperser at 8000-15000 rpm for 1-5 hours to ensure uniform embedding of the powder into the composite network without agglomeration. Then, degas the slurry in a vacuum for 10-30 minutes to remove air bubbles, obtaining a solid electrolyte slurry based on a functionalized bacterial cellulose + conductive polymer composite network.

[0030] In step S3, the number of parts of each raw material added is based on the amount of solvent added, such as deionized water or anhydrous N-methylpyrrolidone (NMP).

[0031] A second aspect of the present invention provides a nano-solid electrolyte slurry, which is prepared by the method of the first aspect of the present invention.

[0032] The nano-solid electrolyte slurry prepared by the method of this invention relies on the synergistic effect of targeted functionalization modification of bacterial cellulose, functionalization treatment of conductive polymers, and in-situ loading of nano-solid electrolytes. This process retains the stable dispersion advantages of the three-dimensional nanofiber network of functionalized bacterial cellulose, effectively suppressing the agglomeration and sedimentation of nano-solid electrolyte powders. The slurry exhibits excellent dispersion stability and long-term storage performance; after 30 days of storage, the particle size change rate and sedimentation rate are both extremely low. Furthermore, the cross-linked composite network formed by the functionalized conductive polymers and functionalized bacterial cellulose constructs a continuous and efficient conductive pathway, preserving the high conductivity of the nano-solid electrolyte itself. The ionic conductivity characteristics significantly improve the ion conduction efficiency of the slurry. At the same time, the slurry does not require a special high-volume binder and is highly compatible with existing electrode slurry systems. There are no binder system conflicts or uncontrollable side reactions during blending. It can be directly adapted to the blending or coating process of positive and negative electrode materials for semi-solid / all-solid lithium batteries. It can achieve efficient dispersion and loading with low solid electrolyte addition, ensuring a high proportion of active materials in the electrode, which meets the high energy density design requirements of batteries. In addition, the core raw material is green and environmentally friendly bacterial cellulose, and there are no harmful additives in the preparation process. The slurry is also environmentally friendly, and its overall performance is adapted to the process and performance requirements of the all-solid lithium battery industrialization. Detailed Implementation

[0033] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0034] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0036] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0037] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0038] In the example: The bacterial cellulose raw material was purchased from Guilin Qihong Technology and is a bacterial cellulose gel.

[0039] Example 1 A nano-solid electrolyte slurry, prepared by the following method: S1: Targeted functionalization modification of bacterial cellulose: A 90wt% aqueous bacterial cellulose wet gel was stirred at 6000 rpm for 30 min in a high-speed mixer; then, three times its weight of deionized water was added, and stirring continued at high speed for another 30 min to obtain a homogeneous suspension. Subsequently, the modifiers trimethoxysilane (5wt% of dry BC weight) and ethylenediamine (5wt% of dry BC weight) were added, the temperature was raised to 80℃, and the mixture was stirred at 600 rpm for 4 h, with ultrasonic dispersion every 30 min for 5 min to ensure uniform modification. The mixture was centrifuged (8000 rpm, 10 min), washed 2-5 times with deionized water, and dried in a freeze dryer at -30℃ for 20 h to obtain functionalized BC dry powder with a three-dimensional network structure and epoxy-amine groups on the surface. S2: Functionalization of conductive polymer: The conductive polymer material PANI was selected and dispersed in 30 times its weight of deionized water. The dispersion was ultrasonically dispersed for 30 min to obtain a suspension. Then, 5 wt% of dopamine hydrochloride of the total weight of the conductive polymer material was added, and the mixture was stirred at 30°C for 5 h at 500 rpm. After centrifugation, washing, and vacuum drying, the dried polydopamine-modified functionalized PANI was obtained. S3: In-situ loading of nano-solid electrolytes: 2 parts of functionalized bacterial cellulose powder and 0.2 parts of polydopamine-modified functionalized PANI were added to 50 parts of anhydrous N-methylpyrrolidone (NMP). The mixture was ultrasonically dispersed for 30 min, then stirred at 500 rpm for 2 h to form a uniform dispersion. 0.5 parts of hexamethylene diisocyanate (HDI), a crosslinking agent, were added, and the mixture was heated to 40 °C and stirred for 4 h to allow the bacterial cellulose and carbon materials to form a crosslinked composite network through epoxy-amine reactions and polydopamine-amine reactions.

[0040] Add 0.5 parts of commonly used ceramic slurry dispersant (polypyrrolidone) to the composite network matrix, stir for 30 min, and then slowly add 100 parts of nano solid electrolyte powder LLZO with a particle size range of D50=100nm.

[0041] After fully adding the powder, stir at 200 rpm for 2 hours to allow the powder to be initially loaded into the network.

[0042] The powder was then dispersed at 10,000 rpm for 2 hours using a high-shear disperser to ensure uniform embedding of the powder into the composite network without agglomeration. The slurry was then degassed in a vacuum for 20 minutes to remove air bubbles, yielding a solid electrolyte slurry based on a functionalized bacterial cellulose + conductive polymer composite network.

[0043] Example 2 A nano solid electrolyte slurry differs from Example 1 in that, in step S3, the nano solid electrolyte powder is LATP.

[0044] Example 3 A nano solid electrolyte slurry differs from Example 1 in that, in step S3, the nano solid electrolyte powder is Li3InCl6.

[0045] Example 4 A nano solid electrolyte slurry differs from Example 1 in that, in step S3, the nano solid electrolyte powder is Li6PS5Cl.

[0046] Example 5 A nano solid electrolyte slurry differs from Example 1 in that, in step S3, the nano solid electrolyte powder is a mixture of LLZO and Li6PS5Cl in a mass ratio of 1:1.

[0047] Example 6 A nano solid electrolyte slurry differs from Example 1 in that, in step S3, 5 parts of functionalized bacterial cellulose dry powder are added.

[0048] Example 7 A nano-solid electrolyte slurry differs from Example 1 in that, in step S3, 5 parts of functionalized bacterial cellulose dry powder and 0.5 parts of polydopamine-modified functionalized PANI are added.

[0049] Example 8 A nano-solid electrolyte slurry differs from Example 1 in that, in step S3, 0.5 parts of polydopamine-modified functionalized PANI are added.

[0050] Comparative Example 1 A nano solid electrolyte slurry differs from Example 1 in that, in step S3, 2 parts of functionalized bacterial cellulose dry powder and 0.2 parts of polydopamine-modified functionalized PANI are not added.

[0051] Comparative Example 2 A nano-solid electrolyte slurry differs from Example 1 in that, in step S3, 0.2 parts of polydopamine-modified functionalized PANI are not added.

[0052] Comparative Example 3 A nano solid electrolyte slurry differs from Example 1 in that, in step S3, two parts of functionalized bacterial cellulose dry powder are not added.

[0053] Slurry performance testing 1. Slurry dispersion stability test. Test method: After sealing the slurry, it was stored at room temperature. After 30 days, samples were taken and the D50 particle size of the nano solid electrolyte powder in the slurry was measured using a laser particle size analyzer; at the same time, the sedimentation rate of the slurry was tested.

[0054] 2. Conductivity test of the cured film. Test method: The slurry was coated on a glass substrate and dried under vacuum at 80℃ for 4 hours to prepare a cured film with a thickness of 30 μm; the ionic conductivity was tested using an electrochemical workstation. The results are shown in Table 1.

[0055] The tests were conducted at room temperature, using stainless steel as the blocking electrode to form a stainless steel|electrolyte|stainless steel symmetrical structure. The tests were performed in a glove box to avoid moisture interference. AC impedance spectroscopy was performed in the frequency range of 1 Hz to 1 MHz, with each sample tested three times and the average value obtained.

[0056] Settling rate = ((weight percentage of bottom settling material - weight percentage of slurry powder) / weight percentage of slurry powder) × 100%; that is, based on the slurry concentration (mass percentage of powder); after storing for 30 days, take the bottom slurry, weigh it, dry it and calculate the mass percentage of powder to obtain the mass percentage of bottom settling material, and then calculate the settling rate according to the formula.

[0057] Table 1

[0058] The test data in Table 1 clearly show the significant differences in dispersion stability (initial D50, 30-day D50 change rate, sedimentation rate) and electrochemical performance (membrane ionic conductivity) of nano-solid electrolyte slurries prepared with different formulations. Combined with the formulation difference analysis of the examples and comparative examples, the following conclusions can be drawn: First, the preparation method of this invention can significantly improve the dispersion stability and storage performance of the slurry. The slurries of Examples 1-8 (using a functionalized BC + functionalized conductive polymer composite system) showed a D50 change rate of only 2.5%~3.9% and a sedimentation rate of only 2.6%~3.9% after standing at room temperature for 30 days. The powder particle size showed almost no significant change, and there was no obvious sedimentation phenomenon. This indicates that the three-dimensional network structure of functionalized BC provides a stable loading space for the nano-solid electrolyte powder, and the in-situ loading process effectively inhibits the agglomeration and sedimentation of the nano-powder, giving the slurry excellent long-term dispersion stability.

[0059] In contrast, Comparative Examples 1 and 3, which did not contain functionalized BC, showed a 30-day D50 change rate of 15.5% to 16.3% and a sedimentation rate of 17.6% to 19.5%, indicating serious powder agglomeration and sedimentation problems. This proves that functionalized BC is the core key to improving the dispersion stability of slurry, and its absence will lead to a significant decrease in the storage performance of slurry.

[0060] Furthermore, as shown in Table 1, the synergistic effect of functionalized BC and functionalized conductive polymer is the core of improving the ionic conductivity of the slurry. The membrane ionic conductivity of all examples is significantly higher than that of the comparative examples, with Examples 3 (halide Li3InCl6) and 4 (sulfide Li6PS5Cl) even reaching 2.56 × 10⁻⁶. -3 S / cm, 1.83×10 -3 The S / cm ratio is far superior to that of the oxide system, indicating that the preparation method of the present invention can fully preserve the high ionic conductivity characteristics of different types of nano solid electrolyte powders.

[0061] Comparative Example 2, which only added unmodified BC and non-functionalized conductive polymer, had a dispersion stability close to that of the Example (D50 change rate 2.8%, sedimentation rate 3.8%), but its ionic conductivity was only 3.26 × 10⁻⁶. -4S / cm, much lower than 5.36 × 10 in Example 1. -4 The S / cm value demonstrates that a single functionalized BC can only solve the dispersion problem. The composite of functionalized conductive polymers is a necessary condition for constructing a continuous conductive pathway and improving ionic conductivity. Only through the synergy of the two can the slurry achieve the dual properties of high dispersion and high conductivity.

[0062] Comparative Example 1, lacking BC and conductive polymers, exhibited not only extremely poor dispersion stability but also the lowest ionic conductivity of all groups (2.91 × 10⁻⁶). -4 The S / cm further verifies the irreplaceable nature of the two core components in this invention.

[0063] Furthermore, as shown in Table 1, different types of nano solid electrolyte powders are compatible with the method of this invention, and fine-tuning of the formulation parameters does not affect the core performance.

[0064] Examples 1-5 of oxides (LLZO, LATP), halides (Li3InCl6), sulfides (Li6PS5Cl) and mixed powder systems all maintained excellent dispersion stability and high ionic conductivity, indicating that the preparation method of the present invention has good adaptability to different types of nano solid electrolyte powders and has a wide range of applications.

[0065] In Examples 6-8 and Comparative Examples 7-8, by fine-tuning the amount of functionalized BC and functionalized conductive polymer added, the D50 change rate and sedimentation rate of the slurry remained at a low level, and the ionic conductivity did not decrease significantly. This indicates that the formulation parameters of the present invention have a certain adjustment range, and fine-tuning within a reasonable range will not affect the core performance of the slurry, demonstrating strong process flexibility.

[0066] In summary, the technical solution of this invention effectively solves the core pain points of existing technologies. Existing technologies suffer from the difficulty of simultaneously achieving both dispersion stability and conductivity. This invention, through targeted functionalization modification of bacterial cellulose, functionalization treatment of conductive polymers, and in-situ loading of nano-solid electrolytes, achieves simultaneous improvement in both. This results in a slurry that possesses both long-term dispersion stability and high ionic conductivity, while also being compatible with different types of solid electrolyte powders. This overcomes the core technical deficiencies of traditional slurries in electrode blending / coating applications.

[0067] In summary, the data in Table 1 fully verify the effectiveness and superiority of the preparation method of the present invention. The prepared nano solid electrolyte slurry fully meets the stringent requirements of semi-solid / all-solid lithium battery electrode mixing and coating for slurry dispersion stability and ionic conductivity, and has industrial application value.

[0068] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for preparing a nano-solid electrolyte slurry, characterized in that, Includes the following steps: S1: Targeted functionalization modification of bacterial cellulose: Introducing organic functional groups to modify the surface of bacterial cellulose to obtain functionalized bacterial cellulose; S2: Functionalization of conductive polymers: Functional modification of conductive polymers to obtain functionalized conductive polymers; S3: In-situ loading of nano-solid electrolyte: In-situ loading of nano-solid electrolyte powder into a composite network matrix formed by the bacterial cellulose and the functionalized conductive polymer.

2. The preparation method according to claim 1, characterized in that, The organic functional groups include amine groups or epoxy groups.

3. The preparation method according to claim 1, characterized in that, In step S1, the method for surface modification of bacterial cellulose by introducing organic functional groups includes: stirring a bacterial cellulose wet gel containing 80-95 wt% water at a speed of 3000-9000 rpm for 10-60 min, then adding deionized water and continuing to stir for 5-60 min to obtain a suspension, adding a modifier containing the organic functional groups, heating to 30-100℃, stirring at a speed of 300-1000 rpm, then centrifuging, washing with deionized water 2-5 times, and drying in a freeze dryer at -30-60℃ for 10-30 h to obtain functionalized bacterial cellulose.

4. The preparation method according to claim 1, characterized in that, The conductive polymer includes at least one of polypyrrole, polyaniline, and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate.

5. The preparation method according to claim 1, characterized in that, The functionalized reagents include dopamine hydrochloride.

6. The preparation method according to claim 1, characterized in that, The nano-solid electrolyte powder includes oxide nano-solid electrolyte powder, sulfide nano-solid electrolyte powder, or halide nano-solid electrolyte powder.

7. The preparation method according to claim 1, characterized in that, The particle size of the nano-solid electrolyte powder is D50 = 20-200 nm.

8. The preparation method according to claim 1, characterized in that, In step S3, the nano-solid electrolyte powder is in situ loaded onto the composite network matrix formed by the bacterial cellulose and the functionalized conductive polymer. This step includes: The functionalized bacterial cellulose and functionalized conductive polymer are added to the solvent and dispersed to form a uniform dispersion. A crosslinking agent is added, and the mixture is heated and stirred to allow the functionalized bacterial cellulose and functionalized conductive polymer to react and form a crosslinked composite network matrix. A ceramic slurry dispersant is added to the crosslinked composite network matrix, followed by the nano-solid electrolyte powder. The mixture is stirred at 100-500 rpm for 1-3 hours to load the nano-solid electrolyte powder into the network. Subsequently, the mixture is dispersed at 8000-15000 rpm for 1-5 hours to ensure that the nano-solid electrolyte powder is uniformly embedded in the composite network. Finally, the mixture is degassed in a vacuum.

9. The preparation method according to claim 8, characterized in that, The solvent includes deionized water or N-methylpyrrolidone; and / or, the crosslinking agent includes hexamethylene diisocyanate.

10. A nano-solid electrolyte slurry, characterized in that, It is prepared by any one of claims 1 to 9.

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