A new porous metallic silicon dicarbide for highly efficient Li-ion battery anode identified by targeted structure search

Extensive efforts have been devoted to C-Si compound materials for improving the limited specific capacity of graphite anode and avoiding the huge volume change of Si anode in Li-ion battery. Here, for the first time we apply the targeted structure search by using Li in desired quantity as chemical template to regulate the bonding between C and Si, which makes searching more feasible for us to find a new stable phase of C2Si (labelled as T-C2Si) that can better fit the XRD data of silicon dicarbide synthesized before. Different from the conventional semiconducting silicon carbides, T-C2Si is not only metallic with high intrinsic conductivity for electrons transport, but also porous with regularly distributed channels in suitable size for Li ions experiencing a low energy barrier. T-C2Si exhibits a high specific capacity of 515 mA/g, a high average open-circuit voltage of 1.14 V, a low volume change of 1.6%. These parameters meet the requirements of an ideal anode material with high performance for electric vehicles. Moreover, our targeted search strategy guarantees the resulting anode material with a desirable specific capacity and a small volume change during charging/discharging, and it can be used to find new geometric configurations for other materials. (C) 2018 Elsevier Ltd. All rights reserved.