A superb 3D composite lithium metal anode prepared by in-situ lithiation of sulfurized polyacrylonitrile

Abstract

Lithium metal has been regarded as the most promising anode for the next generation high energy- density batteries. However, detrimental side reactions with electrolyte, uncontrollable lithium dendrite growth, distinct volume expansion and fragile solid electrolyte interface (SEI) layer lead to low coulombic efficiency (CE), rapid battery failure and even safety hazards, which hinders its practical application. Herein, we propose a novel composite anode which embeds Li metal particles into a Li+/electron hybrid conductive framework and is reinforced by CNTs. Sulfurized pyrolyzed poly(acrylonitrile) (S@pPAN), which is extensively studied as superior cathode materials, is creatively adopted to render abundant Li3N and Li2S on the surface of the Li particles and in the free-space. The in-situ formed hybrid framework not only provides a rapid Li+ transfer channel throughout the electrode, but also suppresses the Li dendrite growth and inhibits the volume expansion. With further assistance of lithiophilic nano-MgO, the composite anode achieved dense and reversible Li plating/striping. As a result, a long cycle life of more than 800 hours with 10 mAh cm−2 and excellent electrode kinetics are obtained for symmetric cells. Moreover, the full cells coupled with S@pPAN and LiFePO4 cathodes deliver a long and stable cycle life. The rational 3D composite anode design provides a feasible strategy to build high performance Li metal batteries.