Stabilizing lithium metal anodes with lightweight fiber/particle composites

Lithium metal anodes face significant challenges, including uncontrolled dendrite growth and limitless volume changes during cycling. Traditional skeletons, such as alloying (e.g., Li 13 In 3 , Li 22 Sn 5 ) or using commercial composite substrates (e.g., Cu strips, nickel foam), often introduce excessive mass, severely compromising the overall mass energy density of batteries. In this work, we synthesize a lightweight and stable fiber/particle composite skeleton by smelting AlB 2 powder with Li ingots to form LiB fibers and Li 9 Al 4 nanoparticles. The as-synthesized Li-B-Al (LBA) anode effectively mitigates volume changes and provides fast ion-conductive and electronic paths through its heterogeneous continuous architecture. Simultaneously, it suppresses lithium dendrite formation by offering low nucleation overpotential and reduced diffusion energy barriers. As a result, the LBA anodes achieve an ultrahigh coulombic efficiency of 99.90% and an ultralow nucleation overpotential of 2.5 mV at 1 mA cm -2 . When paired with LiFePO 4 cathodes (single-side mass loading of 13 mg cm -2 ), the LBA|LiFePO 4 full cells demonstrate exceptional cycling stability, retaining 91.5% capacity after 475 cycles at 1 C and 97.5% capacity after 345 cycles at 2 C. This study presents an effective strategy to enhance the stability of lithium metal anodes and offers a promising pathway toward dendrite-free lithium metal batteries.