Garnet and Li29Zr9Nb3O40 Modified PEO‐based Hybrid Solid Electrolytes for All‐solid‐state Lithium Metal Batteries

Abstract Inorganic‐organic hybrid solid electrolytes (HSEs) are an important category of electrolyte materials for solid‐state batterie. It is of interest and importance to investigate the influence of composition and content of inorganic fillers on the electrochemical performance of HSEs. In this paper, we fabricated HSEs using polyethylene oxide (PEO) as matrix and incorporating different inorganic powders as active fillers. A series of HSEs with different contents of Ga/Nb co‐substituted garnet oxide (Li 6.35 Ga 0.15 La 3 Zr 1.8 Nb 0.2 O 12 , GN‐LLZO) and Y‐doped Li 29 Zr 9 Nb 3 O 40 (Li 29.3 Zr 8.7 Y 0.3 Nb 3 O 40 , 0.3Y‐LZNO) were carefully designed. The ionic conductivity of these PEO‐based HSEs were studied, and their performance in solid‐state lithium‐ion batteries with LiFePO 4 (LFP) as cathode material and Li metal as anode were evaluated. The results showed that the HSE with addition content of inorganic powders, namely PEO LiTFSI @5 % GN‐LLZO +5 %0.3Y‐LZNO (noted as PL3) showed the optimized ionic conductivity of 2.9×10 −4 S cm −1 at room temperature with an activation energy E a of 0.21 eV. It has an electrochemical stability window of 4.65 V and ionic transfer number of 0.242. The addition of inorganic powders not only enhanced the ionic conductivities of PEO‐based HSEs, but also exhibited superior stability and interfacial compatibility with electrodes, leading to the improved cycle stability in the LFP/PL3/Li solid‐state battery configuration.