Hard SiOC Microbeads as a High-Performance Lithium-Ion Battery Anode

Silicon oxycarbide (SiOC) ceramics are attractive materials for anodes of lithium-ion batteries, because of their excellent structural stability and high rate capability. Nonetheless, complex production procedures hinder their commercialization. This work proposes a simple emulsion templating method using liquid pore-forming agent to prepare hard SiOC microbeads, which feature spherical morphology (∼35 μm in diameter) and large specific surface area (217 m2 g–1). Moreover, the produced SiOC microbeads have a hard and dense surface, which significantly improves the structural stability during the process of lithiation/delithiation. A discharge specific capacity of 805 mAh g–1 was reached after 300 cycles, using a current density of 360 mA g–1, and 420 mAh g–1 was recorded after 1000 cycles, even at an ultrahigh current density of 3600 mA g–1. The porous interior structure and the disordered carbon structure of the SiOC microbeads are contributory factors due to the fast mobility of Li+ in the SiOC matrix, related to the coefficient of Li+ diffusion (4.5 × 10–6 cm2 s–1) and eventually the rate capability of the material. Consequently, anodes of lithium-ion batteries with high performance can be produced via this fast and simple preparation method.