Improved electrochemical capacity of precursor-derived Si(B)CN-carbon nanotube composite as Li-ion battery anode.

We study the electrochemical behavior of precursor-derived siliconboron carbonitride (Si(B)CN) ceramic and Si(B)CN coated-multiwalled carbon nanotube (CNT) composite as a lithium-ion battery anode. Reversible capacity of Si(B)CN was observed to be 138 mA h/g after 30 cycles, which is four times that of SiCN (~25 mA h/g) processed under similar conditions, while the Si(B)CN-CNT composite showed further enhancement demonstrating 412 mA h/g after 30 cycles. Improved performance of Si(B)CN is attributed to the presence of boron that is known to modify SiCN's nanodomain structure resulting in improved chemical stability and electronic conductivity. Post-cycling microscopy and chemical analysis of the anode revealed formation of a stable passivating layer, which resulted in stable cycling.