3D pomegranate-like structured Si@void@Ni@C microspheres as high-performance anode in lithium-ion batteries

Abstract

Due to its high theoretical capacity (4200 mAh g−1), appropriate charging potential (∼0.5 V vs Li+/Li), and abundant raw material sources, silicon anode material is considered to be an ideal anode material for lithium-ion batteries. However, its low intrinsic conductivity and huge volume expansion (∼300%) during the lithiation process seriously reduce the cycle life of the battery, causing the battery's capacity to rapidly decay. In this work, 3D pomegranate-like structured Si@void@Ni@C microspheres are designed and synthesized through hydrothermal and carbonization methods. In this unique structure, the supporting layers, including carbon and nickel layers, can not only improve conductivity but also offer sufficient space to alleviate the volume expansion of silicon particles during the lithium insertion/extraction process. Combined with the above advantages, the 3D pomegranate-like structured Si@void@Ni@C microspheres anode shows excellent electrochemical performance, such as high first discharge capacity (1697 mAh g−1), fine cycle stability (0.23% capacity attenuation rate for each cycle), and excellent rate performance (97.7% capacity recovery rate).