Electron redistribution and strain buffering in SnZn embedded nitrogen-doped carbon fiber toward dendrite-free lithium metal batteries via solid-solution alloying reactions.

Lithium metal batteries are promising candidates for next-generation high-energy-density storage devices. However, their development is still plagued by the severe issue of lithium dendrite growth. Herein, we report a self-supporting host composed of SnZn nanoalloy supported on porous N-doped carbon nanofibers (SnZn@PCF) with controllable deposition of Li. The N-doped porous conductive carbon framework enables uniform lithium deposition by spatial confinement of metallic lithium within the matrix, thereby mitigating local current density and suppressing dendrite growth. Density functional theory calculation reveals that the lithiophilic SnZn alloy provides homogeneous nucleation sites with a reduced nucleation barrier, thereby facilitating uniform lithium nucleation and controlled growth. Operando XRD and SEM characterization evidences a reversible solid-solution alloying mechanism in SnZn@PCF host, enabling efficient and stable lithium storage. Accordingly, the SnZn@PCF achieves dendrite-free Li plating/stripping with a Coulombic efficiency of 97.7% for over 300 cycles at 1 mA cm-2, alongside stable symmetric cell cycling exceeding 1700 h. When paired with a commercial LiFePO4 cathode, the anode-less SnZn@PCF||LFP full cells deliver cycling stability with a capacity retention of 90.1% over 90 cycles at 1C.