Wrinkled, partially-graphitized carbon encapsulated silicon with preformed voids as lithium-ion battery anode with enhanced cyclic and rate performances

It is challenging to conveniently synthesize silicon/carbon composites that simultaneously possess some important attributes which can enhance the cyclic and rate performances of silicon-based anode, such as partial graphitization, flexible nanostructure , preformed spaces, and optimized pore structure . Herein, we utilize a MgO product obtained from magnesiothermic reduction as an autogenetic template and catalyst to prepare wrinkled, graphitized carbon encapsulated silicon composite with preformed spaces. As a result, the as-fabricated composite exhibits a high specific capacity of ~983 mAh g -1 at a current density of 1.2 A g -1 , and it is able to achieve 60% capacity retention after 400 cycles. Even under a high current density of 3.2 A g -1 , the composite is still able to deliver a specific capacity of ~790 mAh g -1 . Based on the post-mortem investigation, the anode exhibits low impedance and complete encapsulated structure after repeated cycling. • A facile strategy for fabricating Si@C composites with delicate structures. • The autogenerated MgO nanoflakes are utilized as autogenous templates as well as the catalyst of carbon graphitization. • The as-fabricated composite exhibits a high specific capacity of 983 mAh g -1 at a current density of 1.2 A g -1 . • The Si@C composite is able to achieve 60% capacity retention after 400 cycles.