Unveiling the Impacts of Charge/Discharge Rate on the Cycling Performance of Li-Metal Batteries

Lithium metal batteries (LMBs) offer superior energy density and power capability but face challenges in cycle stability and safety. This study introduces a strategic approach to improving LMB cycle stability by optimizing charge/discharge rates. Our results show that slow charging (0.2C) and fast discharging (3C) significantly improve performance, with a multilayer LMB retaining over 80% capacity after 1000 cycles. Fast discharge rates promote lithium plating beneath the SEI layer, suppressing its growth and improving Coulombic efficiency, whereas slow discharge rates facilitate lithium plating above the SEI, leading to SEI accumulation. We propose a rational hypothesis linking SEI conductivity and cycling conditions and introduce an intermittent pulse discharge protocol to emulate electric vehicle applications, further improving the stability. These optimized cycling strategies enhance the LMB lifespan, utility, and safety, paving the way for broader market adoption in the years ahead.