Solvation regulation and interphase stabilization enabled by a BiF3-MOF composite electrolyte for high-performance lithium metal anodes

Despite their high energy density, lithium metal batteries (LMBs) remain hindered in practical applications by the intrinsic instability of the lithium metal anode. Owing to its high reactivity, lithium readily forms a fragile and heterogeneous solid electrolyte interphase (SEI), leading to nonuniform Li deposition, dendrite growth, and consequent safety risks and rapid capacity decay. In this work, a quasi-solid-state electrolyte (QSE) incorporating a BiF 3 -decorated metal-organic framework (MOF) is developed to stabilize lithium metal anodes. The BiF 3 nanoparticles confined within the MOF regulate the Li + solvation sheath through interactions with solvent molecules, thereby facilitating Li + transport and delivering an ionic conductivity of 2.0 mS cm −1 with an enhanced Li + transference number of 0.48. In addition, the QSE promotes the in-situ formation of a LiF/Li 3 Bi-rich SEI, which accelerates Li + diffusion, lowers the Li nucleation barrier, and enables uniform and smooth lithium deposition. As a result, lithium metal anodes exhibit markedly improved reversibility and interfacial kinetics. Li||Li symmetric cells achieve a high critical current density of 2.5 mA cm −2 and maintain stable cycling for over 4600 h at 0.2 mA cm −2 . Furthermore, Li||LiFePO 4 full cells demonstrate excellent rate capability and long-term cycling stability, retaining 92.2% of the initial capacity after 1500 cycles at 1C and delivering 72.6 mAh g −1 at 20C. A BiF 3 -MOF composite electrolyte is designed for lithium metal batteries. The BiF 3 nanoparticles within the MOF effectively modulate the Li + solvation sheath by interacting with solvent molecules and thus facilitate efficient Li + transport. Moreover, the QSE promotes the formation of a LiF/Li 3 Bi-rich SEI, which accelerates Li + diffusion, lowers the nucleation barrier, and enables uniform and easy Li deposition. Download: Download high-res image (105KB) Download: Download full-size image