Spatial Isolation of Oversized Lithium and Separator via Janus Carbon Fabric Anode for Safer and Steadier Lithium Metal Batteries

Although Li metal is regarded as a promising anode material, the undesired dendritic growth and continuous consumption of lithium during battery cycling result in severe safety risks and low Coulombic efficiency. Herein, a critical spatial-isolation strategy is demonstrated to separate the originally adjacent lithium metal and separator for higher safety and stability of lithium metal batteries by designing a Janus carbon fabric (CF) anode. Transferring lithium from the anode/separator interface to CF bottom shuts down the prerequisite of lithium dendrite formation, while the oversized lithium at CF bottom can be also used to compensate for the loss of lithium during the charge-discharge cycling. As a result, the Janus CF//Li anode exhibits an ultralong cyclic life of 450 h at 2 mA cm⁻² and >250 h at 4 mA cm⁻², which significantly exceeds the common CF//Li anodes. Full cells coupling the Janus CF//Li anodes demonstrate longer cycle life (550 cycles) than that of the CF//Li anodes (450 cycles) at 1C, along with higher rate capability, and excellent cyclic stability at 2C. The remarkable results, as a proof of concept, signify the superior anode structure for improving both battery safety and cyclic stability for the realistic application of lithium metal batteries.