Multilayer boron doped Si@SiOx/C from Si-Ca alloy for lithium-ion battery anodes

Abstract

SiOx has been considered as a promising anode for next-generation lithium-ion batteries. However, the poor rate performance caused by the low electrical conductivity is a bottleneck of its application. Approaches involving carbon composites, boron doping and two-dimensional structure have been pursued to improve the electrical conductivity. In this work, through the combination of these strategies, a multilayer boron doped Si@SiOx/C composites are fabricated by a chemical exfoliation of CaSi2 with B2O3 and CaCO3. The production exhibits favorable properties for lithium-ion battery anodes, such as proper specific surface area, complete multilayer structure, boron doped and carbon composite structure. The as-obtained B-Si@SiOx/C-700 delivers a capacity of 659.3 mAh g−1 after 500 cycles at 1 A g−1. Especially, at 4 A g−1, the capacity retention of the B-Si@SiOx/C-700 anode is still 40.9 % of its average discharge capacity at 0.2 A g−1. The capacitive contribution to the total Li+ storage capacity for the B-Si@SiOx/C-700 electrode is 83.6 % at 1.0 mV s−1. This work presents a simple and efficient strategy to construct a multilayer doped structure to improve electrochemical properties.