Confronting the Issues Associated with the Practical Implementation of Zinc Blende-type SiC Anodes for Efficient and Reversible Storage of Lithium Ions

Electrochemically active zinc blende anodic materials have been envisioned to host Li+ ions at tetrahedrally configured interstitial sites, resulting in minimum volumetric expansion. Despite the silicon carbide (beta-SiC) being a zinc blende system with a high theoretical specific capacity (similar to 1430 mAh/g) and structural robustness, it has not been studied to the extent that its other peers like Si/graphite/Sn/Al, etc. have been. By identifying and addressing the issues that currently limit commercially available beta-SiC's practically achivable storage ability, we can unlock its potential as a viable anodic material for Lii+-ion battery (LIB). In this work, comprehensive structural studies on commercially procured different batches of beta-SiC unveil the presence of a native suboxide passivation layer. This suboxide layer adversely affects the Li+-ions diffusion kinetics besides poor initial Coulombic efficiency and inferior reversible capacity (similar to 79 mAh/g @ 128th cycle). The removal of this suboxide passivation layer immediately brings a 5-fold increase in Li+-ions diffusion kinetics and an similar to 53% increase in the first reversible specific capacity. The study shows the need for further assistance to increase the Li+-ions diffusion, and the surface modification by N-doped carbon is found to be competent enough to bring an similar to 35-fold increase in overall lithium diffusion kinetics. This results in a noticeable increase in reversible specific capacity by more than an order of magnitude from similar to 79 to similar to 930 mAh/g. The modified SiC-based anodes are found to be compatible when paired with commercially available LiCoO2 in full-cells. The LiCoO2//SiC-based full cell demonstrates the capacity retention of nearly 80% post 175 cycles and is well capable of powering prototype portable electronic devices, too. The overall study suggests that commercially available silicon carbide materials are worthy of consideration as negative electrodes in LIB upon deliberate surface engineering and should be given a chance.