Dispersibility Of Nano-lithium Lanthanum Zirconium Tantalum Oxide Solid Electrolyte Powder And Its Application In Solid-state Lithium Batterie

Solid-state Lithium batteries（SSLBs）have received widespread attention for their significant advantages in energy density and safety.As the key material of SSLBs,the composite membrane electrolytes composed of solid electrolyte play an important impact on the energy density,rate,cycle and safety performance of the battery.Organic-inorganic composite membrane electrolytes are important research direction on SSLBs,benefiting from combining the easy processability of the polymer electrolytes and the thermal stability and high ionic conductivity of the ceramic electrolytes.This paper focuses on the uniform dispersion of solid oxide electrolyte nanoparticles in organic solvents and polymer electrolytes,which effects on composite membrane electrolytes and battery performance.The specific work content and results are as follows:（1）The 3-glycidyloxypropyl trimethoxy silane（GPTMS）layer with a thickness of about 5 nm was realized to uniformly coat the surface of the LLZTO nanoparticles by using the interaction of GPTMS with the hydroxyl group on the surface of Li_6.4La₃Zr_1.4Ta_0.6O₁₂（LLTZO）nanoparticle.After modification with GPTMS,LLZTO particles can be homogeneously dispersed in N-Methylpyrrolidone（NMP）,N,N-Dimethylformamide（DMF）and acetonitrile（ACN）solution.The D₅₀ of LLZTO particles decreases to 279 nm,50 nm and 43 nm in NMP,DMF and ACN,respectively.And the particle-size-distribution experiments reveal that LLZTO-nanoparticle dispersity is positively correlated with solvent polarity.（2）By comparing the PEO-based composite membrane electrolytes prepared by LLZTO and GPTMS-modified LLZTO dispersion,it was observed that the LLZTO@GPTMS nanoparticles had no obvious agglomeration in the polymer,and the dispersibility was significantly better than that of the LLZTO nanoparticles.The PEO:LLZTO@GPTMS composite membrane electrolytes exhibit an enhanced ionic conductivity of 2.31×10^-4 S cm^-1 at room temperature.The symmetric lithium batteries with PEO:LLZTO@GPTMS composite membrane electrolytes can be cycled stable over200 h at 0.2 mA cm^-2 and 45℃.Meanwhile,the SSLBs assembled by LiFePO₄ cathode and lithium metal anode provide reversible capacity of 140 mAh g^-1.（3）In the N-methylpyrrolidone（NMP）solution,polyvinylidene fluoride（PVDF）was further added to form a LLZTO@GPTMS/PVDF slurry that can be homogeneously coated on the separators.Among them,the solid electrolyte separator with polyimide（PI）as support,the assembled LiFePO₄/Li battery delivered discharge capacity of 151 mAh g^-1 at30℃ and 0.1 C.In addition,the capacity retention of 99.5%was maintained after 70 cycles.The LLZTO-coated separators adopt a support that has been commercialized,which is easy to manufacture and also gives the LLZTO@GPTMS nanoparticles a new practical value.The results show that the modification of surface functional groups can improve the uniform dispersion of solid oxide electrolyte nanoparticles in organic solvents and polymer matrices,further enhancing the performance of organic-inorganic composite membrane electrolytes and batteries,which provides an effective solution for preparing high-energy density and high-safety SSLBs.