Sulfur and nitrogen codoped Nb2C MXene for dendrite-free lithium metal battery

Abstract Lithium (Li) metal is considered as a promising anode for next-generation energy storage systems, but uncontrollable dendrite and low Coulombic efficiency (CE) impede their commercialization. Herein, by confining Li into sulfur and nitrogen codoped Nb2C MXene, a more practical Li anode with high performance has been synthesized. S and N doping sites serve as extrinsic defects and active sites for reaction, as well as enhance its electroconductivity. Compared with undoped Nb2C, N and S codoped Nb2C is more lithiophilic with synergistic effect, as verified by both density functional theory (DFT) calculation and electrochemcial experiments. Hence, the codoped Nb2C can be used as three dimensional (3D) lithiophilic and conductive host, guiding hostless Li metal to nucleate and plate uniformly. Moreover, the introduction of heteroatoms can broaden the interlayer spacing and stabilize the structure of MXene, avoiding its pulverization and restacking during cycling. As a result, the as-developed Li metal anodes are armed with strong dendrite inhibiting ability and show excellent electrochemical performance, such as high CE, long lifespan and prominent practical performance in full cell. The codoped Nb2C MXene can provide a new avenue for the development of alkali metal batteries and shed light on the research of suppressing dendrite growth.