Flexible Si3C monolayer: A superior anode for high-performance non-lithium ion batteries

Due to the low cost, suitable redox potentials and intrinsic safety, non-lithium ion batteries (NLIBs) have attracted considerable attention in the next-generation energy storage systems; nonetheless, searching for efficient anodes is still a great challenge in the development of NLIBs. Herein, we systematically estimated the potential of emerging 2D Si3C as an anode of NLIBs by means of first-principles computations. Our results show that Na/K/Ca ions are stably adsorbed on the Si3C surface with adsorption energies of - 0.81 to - 0.17 eV. However, the positive adsorption energy implies Si3C is an inefficient anode for Mg/Al-ion batteries. During the metal ion intercalation, a semiconductor to metal transition is observed, suggesting that the Si3C anode could ensure superb conductivity for fast electronic transport. In addition, the metal ions diffuse rapidly on the Si3C surface with small energy barriers. Nonetheless, the presence of defects in Si3C severely degrades the ion mobility. Remarkably, the efficient accommodation of Na/K/Ca ions yields a high specific capacity of 1113.58, 835.18 and 2227.15 mA h g(-1). The Si3C anode also possesses moderate mechanical stiffness and excellent structural flexibility, which are beneficial to achieve a favorable reversibility. All these results indicate that Si3C is a superior anode candidate for high-performance Na/K/Ca-ion batteries.