Overcoming the Trade-Off between Ion Conduction and Stability Using Thin Composite Solid Electrolyte for High Performance All-Solid-State Lithium Battery

Inorganic superionic conductors hold great promise for all-solid-state lithium batteries because of their superior ionic conductivity. However, their application as electrolytes is limited by trade-off between ion conduction and stability. Here, a thin composite solid electrolyte, vermiculite-Li 0.33 La 0.557 TiO 3 /poly(ethylene oxide) (Vr-LLTO/PEO), is prepared by in-situ co-sintering an interconnected Vr-LLTO framework and then impregnating PEO. Within this electrolyte, the continuous LLTO on Vr nanosheet acts as efficient pathways for vertical Li + transfer with reduced grain boundary resistance. Together with the thin thickness (35 μm), Vr-LLTO/PEO electrolyte attains high ionic conductivity of 1.04 × 10 -4 S cm -1 at 25 o C, over three times of LLTO pellet and surpassing most reported ceramic electrolytes. Furthermore, the disordered stacked Vr nanosheets are covalently linked by LLTO, which imparts highly enhanced compressive strength of 319 MPa. In this manner, the trade-off between ion conduction and stability is overcome, which allows the assembled LiFePO 4 /Li cell achieving satisfactory cycling performances: an initial discharge capacity of 150.3 mAh g -1 at 1 C and capacity decay of only 0.08% per cycle after 200 cycles. This study may inspire the subtle design of conductive and stable electrolytes for high-performance devices