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

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. Anode-free lithium metal batteries (AFLMBs) are considered as one of the most promising candidates for next-generation high-energy-density rechargeable lithium batteries. An efficient high-current initiated formation strategy is developed for AFLMBs.