Pencil-drawing on nitrogen and sulfur co-doped carbon paper: An effective and stable host to pre-store Li for high-performance lithium–air batteries

Abstract

Metallic lithium (Li) is regarded as the ultimate anode for high-energy-density rechargeable batteries due to its highest theoretical capacity and most electronegative potential. However, there are serious challenges before practical application of Li metal batteries (e. g. Li–air batteries), including the dendritic Li formation and infinite variation of electrode dimension. Herein, nitrogen (N) and sulfur (S) co-doping carbon paper (NS-CP) is synthesized and further modified with a graphite-based layer (GL) by pencil-drawing. The as-prepared GL modified NS-CP (GL/NS-CP) is applied to pre-store Li through the heating-infusion method and Li-GL/NS-CP electrode is obtained. Experimental and theoretical results have demonstrated that N, S co-doping can effectively enhance the lithiophilicity of CP to ensure the uniform Li deposition. In addition, GL presents excellent Li wettability to rapidly syphon molten Li. Moreover, abundant pores in GL/NS-CP can accommodate enough Li to alleviate electrode volume change and lower local current density to restrain Li dendrites. Compared with pure Li anode, Li-GL/NS-CP electrode shows more stable voltage curves with lower overpotential (20 ​mV for 600 cycles). As a result, Li–air batteries with Li-GL/NS-CP anodes also exhibit the satisfying cycling life. These results have shed a new light on the development of Li anodes.