High-conductive polymer-in-porous garnet solid electrolyte structure for all-solid-state lithium batteries enabled by molecular engineering

The ceramic-based hybrid solid electrolytes (HSEs) represent excellent promise for application in next generation all-solid-state lithium metal batteries (ASSBs) due to their fast Li-ion migration, high mechanical strength, and good interfacial stability with electrodes. Herein, a novel HSE structure is designed featuring a polymer-infiltrated porous ceramic cubic Li6.1Al0.3La3Zr2O12 (c-LLZO) scaffold fabricated by an integrated sintering method. The HSE structure exhibits high intrinsic ionic conductivity as well as good mechanical strength with even distribution of the polymer phase (LiTFSI-doped PEO) within the network of open pores resulting in uniform Li-ion migration flux. The infiltrated polymer solid electrolyte (PSE) forms strong molecular bonding on the interior and exterior surface of the ceramic skeleton via La-N bonds effectively lowering the interfacial impedance between two phases. Moreover, this continuous two-phase interface provides a fast pathway for Li-ion transport. Thus, the as-designed ceramic-based HSE demonstrates high Li-ion transference number (0.71) and ionic conductivity (0.547 mS cm-1) at 25 °C. The ASSBs (Li/HSE/LFP) enabled by the ceramic-based HSEs exhibit high discharge specific capacities of 163 mAh g-1 at 0.1 C and average coulombic efficiency greater than 99 % after 50 cycles. This novel design opens new possibilities in our pursuit for next generation high-performance ASSBs.