Rational design of hollow tubular SnO2@TiO2 nanocomposites as anode of sodium ion batteries

As an anode material for sodium ion batteries (SIBs), SnO2 has a large theoretical capacity of 1378 mA h g(-1). However, the poor cyclic stability caused by its serious volume expansion during the charge/discharge process has become the biggest obstacle to its practicability. In this paper, one-dimensional tubular SnO2@TiO2 core-shell nanocomposites were designed and synthesized for the first time to inhibit the volume change of SnO2 during (de)sodiation process, thus greatly improving its cyclic stability. The SnO2@TiO2 anode provides a capacity of 316 mA h g(-1) after 50 cycles at a current density of 50 mA g(-1) and the initial Coulombic efficiency (ICE) is 49.7%. By contrast, the corresponding figures are only 200 mA h g(-1) and 29% for pristine SnO2, 179 mA h g(-1) and 32% for TiO2 nanotube, respectively. XPS, TEM and HR-TEM techniques were used to analyze the electronic and geometric structures of the composites. The excellent electrochemical performance of SnO2@TiO2 nanocomposites were further demonstrated by kinetic analysis and the pseudo-capacitive properties of SnO2@TiO2 electrodes were calculated from the aspect of kinetics. It could be inferred that the reasonable structure design is conducive to improve the sodium storage performance of the SnO2@TiO2 composites, and may provide a good solution for further development of SIBs. (C) 2020 Elsevier Ltd. All rights reserved.