Stabilizing Lithium Metal Anodes by Fiber Clustering

Lithium metal anodes generally suffer from uncontrolled dendrite growth and large volume change, while traditional skeletons such as Li13In3 and Li22Sn5 are too heavy and discontinuous to offer highly efficient structural supportability for composite Li anodes. In this work, lightweight and stable fiber-clustered skeletons, which are composed of LiB fibers and jointed Li22Si5 nanoparticles, can be obtained by smelting SiB6 powder and Li ingots. In addition to serving as both ionic and electronic conductors for composite Li anodes, the stable skeletons reduced volumetric fluctuation by offering uniform, heterogeneous, and continuous architectures while suppressing lithium dendrites with low nucleation overpotential and diffusion energy barrier. As a result, the Li–SiB6|Li–SiB6 symmetrical cells achieve an ultralong lifespan over 2000 h cycling at 1 mA cm–2 and 1 mA h cm–2. Eventually, the Li–SiB6|LiFePO4 full cells exhibit a long-term cyclability of 400 cycles with a high-capacity retention of 94.5% at 2 C, and the Li–SiB6|LiCoO2 pouch cells exhibit an impressive 85% capacity retention after 350 cycles. This work develops a new strategy to strengthen the stability of fibrous skeletons and minimize volume changes for dendrite-free Li metal anodes.