Guiding lithium-ion flux to avoid cell's short circuit and extend cycle life for an anode-free lithium metal battery

Abstract The uncontrolled lithium dendrite growth during cycling causes safety issues that impede lithium metal batteries from practical applications. In anode-free lithium metal batteries (AFLMBs), the unregulated plating of lithium on bare copper enforces a more severe growth of lithium dendrite. Herein, we guide the direction of lithium (Li) depositions towards the backside of gold sputter perforated polyimide film (PI@Au), which serves as an anode current collector. Thus, Li can deposit on the surface of PI@Au, and subsequently, Li growth takes place in the direction away from the separator face (ASF). This backside deposition and growth tactic allow the battery to operate safely, even when lithium dendrite exists. Remarkably, the dendrite free separator facing (SF) of PI@Au anode demonstrates highly improve cycling stability. Hence, PI@Au//LFP cell is capable of maintaining capacity retention (CR) of 20% for 340 cycles with an average Coulombic efficiency (Av. CE) of 98.7% (0.5 mA/cm2). In contrast, the control cell (Cu//LFP) runs only for 165 cycles under the same value of CR. This work not only proposes an innovative approach in developing ultra-safe AFLMBs but also validates the feasibility of electrically nonconductive substrates as anode current collectors by modifying their lithiophilicity.