Hollow Boron-Doped Si/SiOx Nanospheres Embedded in the Vanadium Nitride/Nanopore-Assisted Carbon Conductive Network for Superior Lithium Storage.

Abstract

SiOx-based anode materials with high capacity and outstanding cycling performance have gained numerous attentions. Nevertheless, the poor electrical conductivity and non-negligible volume change hinder their further application in Li-ion batteries. Herein, we propose a new strategy to construct a hollow nanosphere with boron-doped Si/SiOx decorated with vanadium nitride (VN) nanoparticles and embedded in a nitrogen-doped, porous, and partial graphitization carbon layer (B-Si/SiOx@VN/PC). Benefiting from such structural and compositional features, the B-Si/SiOx@VN/PC electrode exhibits a stable cycling capacity of 1237.1 mA h g-1 at a current density of 0.5 A g-1 with an appealing capacity retention of 87.0% after 300 cycles. Additionally, it delivers high-rate capabilities of 1139.4, 940.7, and 653.4 mA h g-1 at current densities of 2, 5, and 10 A g-1, respectively, and ranks among the best SiOx-based anode materials. The outstanding electrochemical performance can be ascribed to the following reasons: (1) its hollow structure makes the Li+ transportation length decreased. (2) The existing nanopores facilitate the Li+ insertion/desertion and accommodate the volume variation. (3) The nitrogen-doped partial graphitization carbon enhances the electrical conductivity and promotes the formation of stable solid electrolyte interface layers during the repetitive Li+ intercalation/extraction process.