A “dendrite-eating” separator for high-areal-capacity lithium-metal batteries

To realize the practical applications of the next-generation lithium-metal batteries (LMBs), it is critical to developing high-areal-capacity lithium (Li) anodes with high reversibility and dendrite-free electrodeposition. Herein, we demonstrate a “dendrite-eating” strategy to enable high-areal-capacity LMBs by introducing silicon (Si) coating onto the polypropylene (PP) separator. The Si layer is found to be effective in stabilizing the Li electrodeposition and reduce the Li loss. The in-situ optical cell observation and electrochemical characterizations reveal that the “dendrite-eating” coating serves as both a Li absorbant to suppress (“eat”) the dendrites growth and a backup Li reservoir to replenish the Li loss. With this “dendrite-eating” separator, the Li consumption during cycling is reduced by 66%, and the cyclability and reversibility of the Li anodes are also significantly improved, leading to a prolonged stripping/plating lifetime for >1000 ​h and high Coulombic efficiency (CE) of >97.6% in carbonate electrolyte. Coupled with an industry-level high-loading LiFePO4 cathode (20.0 ​mg ​cm−2), a thin Si coating of only 0.2 ​mg ​cm−2 on the separator remarkably improves the full-cell cycling stability.