Adjusting the Chemical Bonding of SnO2@CNT Composite for Enhanced Conversion Reaction Kinetics

Carbon nanotubes (CNTs) with excellent electron conductivity are widely used to improve the electrochemical performance of the SnO2 anode. However, the chemical bonding between SnO2 and CNTs is not clearly elucidated despite it may affect the lithiation/delithiation behavior greatly. In this work, an SnO2@CNT composite with Sn-C and Sn-O-C bonds as a linkage bridge is reported and the influence of the Sn-C and Sn-O-C bonds on the lithium storage properties is revealed. It is found that the Sn-C bond can act as an ultrafast electron transfer path, facilitating the reversible conversion reaction between Sn and Li2O to form SnO2. Therefore, the SnO2@CNT composite with more Sn-C bond shows high reversible capacity and nearly half capacity contributes from conversion reaction. It is opposite for the SnO2@CNT composite with more Sn-O-C bond that the electrons cannot be transferred directly to CNTs, resulting in depressed conversion reaction kinetics. Consequently, this work can provide new insight for exploration and design of metal oxide/carbon composite anode materials in lithium-ion battery.