Bi-nanofillers integrated into PEO-based electrolyte for high-performance solid-state Li metal batteries

Solid-state lithium metal batteries (SSLMBs) with high safety and high energy densities draw widespread attention in recent years. Nevertheless, the intrinsic defects of the solid-state electrolyte (SSE) such as the poor compatibility with electrodes and low ionic conductivity hamper the application of SSMLBs. Herein, we introduce rigid two-dimensional hexagonal boron nitride (BN) nanosheets and flexible One-dimensional aramid nanofibers (ANFs) as bi-nanofillers into the polyethylene oxide (PEO)-based SSEs to fabricate a composite solid-state electrolyte (CSE) ANF-PEO-BN with network structure boosting the comprehensive performance of SSMLBs. ANF and BN with special properties and structures are prone to be dispersed homogeneously in the PEO matrix to build the ANF-PEO-BN electrolyte, whose rigid and flexible network structure ensures the formation of Li dendrites inhibited. Furthermore, the dissociation of lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) is promoted and more ion transport channels are provided due to the strong affinity between Lewis acid centers of ANF/BN and Li+/TFSI−. As a result, the LiFePO4/Li batteries deliver high-capacity retention of 86% after 500 cycles and Li/Li cells stably cycle beyond 3300 h with small overpotential of 10 mV at 0.1 mA cm−2/0.2 mAh cm−2.