Cyclically formed dual mechanical/functional interface stabilizing silicon with enhanced lithium complementary effect

Abstract

Silicon has been focused as a potential candidate in practical lithium-ion batteries due to its amiable feature of high theoretical specific capacity and environmental friendliness. However, its long-term stability requires further improvements for the significant volumetric expansion during lithium insertion. A novel strategy of a complementary effect created by the special extra lithium-storage capability of transition metal oxides is proposed and explored for the modification of silicon in the study. Si@MnO/C composite with highly compact structure is thus prepared by a facile electrostatic process combined with heat treatment. The results demonstrate that the strategical introduction of ultrafine MnO plays a crucial role in the generation of the complementary effect, which outstandingly enhances the durability as well as the kinetics of silicon anode. A reversible capacity of 1085.7 mAh g⁻¹ with a Coulombic efficiency over than 99% has been obtained after 500 cycles at the current density of 200 mA g⁻¹. Even at a high current density of 2000 mA g⁻¹, a retention capacity of 946.3 mAh g⁻¹ could be maintained after 920 cycles.