A high-current initiated formation strategy for improved cycling stability of anode-free lithium metal batteries†

Abstract

Anode-free lithium metal batteries (AFLMBs) are considered as one of the most promising candidates for next-generation high-energy-density rechargeable lithium batteries. Improving the reversibility of lithium plating/stripping on bare anode current collectors is the key to enabling AFLMBs. Herein, we developed a high-current initiated formation strategy to improve the cycling stability of AFLMBs by regulating the Li nucleation and growth behavior. A great number of ultrafine Li nanospheres with uniform and dense distribution are deposited on the anode current collector during the initial Li deposition at very high current density (10–30 mA cm⁻²). These Li deposits serve as electrochemically active sites and manifest fast kinetics for lithium plating/stripping with enhanced exchange current density and successfully guide uniform dendrite-free Li nucleation/growth. Preferential decomposition of anions in the electrolyte under high current also induces the formation of robust inorganic-rich SEI, which facilitates the interfacial charge transfer and alleviates parasitic reactions. By simply changing the formation strategy, the average coulombic efficiency of Li‖Cu half cells is elevated from 96.8% to 98.5% at 1 mA cm⁻² for 200 cycles and the capacity retention of the Cu‖LiFePO₄ anode-free cell is impressively improved from 34.5% to 54.7% after 100 cycles. Besides, the time consumed for the formation process is effectively reduced by 10.5% after adopting the high-current initiated formation strategy, which could greatly improve the formation efficiency and holds great potential for practical application in AFLMBs.