Defect-rich carbon nitride as electrolyte additive for in-situ electrode interface modification in lithium metal battery

Lithium (Li) metal anode is experiencing the revival of the times due to the constant pursuit of high energy density secondary batteries. However, the problem of Li dendrite caused by irregular Li deposition seriously hinders the development of Li metal batteries. The failure mechanisms of Li-Sulfur (Li-S) pouch cells are revealed by the electrochemical diagram. And the most immediate reason is that the growth of Li dendrites continuously consumes the active lithium and electrolyte, which leads to the pulverization of Li, and further battery failure. Herein, the nitrogen-defective graphite-like carbon nitride (NG-C₃N₄, or NGCN) is employed as electrolyte additive to achieve homogeneous deposition of Li metal and suppress the generation of Li dendrites. In particular, this uniform and adjustable Li deposition can optimize the electrochemical performance of symmetrical Li-NGCN||Li-NGCN cells, even at the areal capacity of 10 mAh cm⁻². Furthermore, the NGCN can achieve the co-deposition with Li-ions during the charge–discharge process to construct the in-situ NGCN coating on the surface of both cathode and anode. Therefore, the Li-NGCN-S/PC pouch cell acquires superb long-term cycling performance with a high discharge capacity of 822.1 mAh g⁻¹ and the capacity retention rate is 67.4% after 100 cycles.