In situ construction of interconnected SnO2/nitrogen-doped Carbon@TiO2 networks for lithium-ion half/full cells

Abstract

A one-pot in situ pyrrole polymerization strategy, followed by controllable atomic layer deposition of TiO2 and pyrolysis process, is carried out to construct the core-shell SnO2/NC@TiO2 with sub-5 nm SnO2 nanoparticles uniformly dispersing in interconnected nitrogen-doped carbon nanospheres coated by TiO2 layer. Benefiting from the unique structural stability of SnO2/NC@TiO2, as anode materials for LIBs, they show much improved cycling stability and rate capability compared with the bare SnO2 and SnO2/NC electrodes. Specifically, the SnO2/NC@TiO2 electrode with a 10 nm TiO2 coating layer demonstrate the optimal lithium ion storage performance, delivering initial discharge capacity of 1224 mAh g−1 with a first-cycle Columbic efficiency of 72.3% and 871 mAh g−1 after 200 cycles at 100 mA g−1. Moreover, the assembled SnO2/NC@TiO2//LiFePO4 full cell demonstrates a good rate capability with a reversible capacity of 145 mAh g−1 (67% capacity retention of the initial value) when the electrode undergoes various current densities after 70 cycles. The improved electrochemical performance is mainly attributed to the surface interface engineering by the interconnected carbon matrix as well as the uniform TiO2 outer layer. These achieved results suggest that interconnected SnO2/NC@TiO2 electrodes have the potential to be used as anode for high-performance lithium ion battery.