Encapsulating homogenous ultra-fine SnO2/TiO2 particles into carbon nanofibers through electrospinning as high-performance anodes for lithium-ion batteries

Abstract

Homogenous ultra-fine SnO2/TiO2 particles encapsulated into carbon nanofibers (SnO2/TiO2@CNFs) with a uniform and ordered one-dimensional fibrous structure are fabricated through facile electrospinning technique and subsequent heat treatments, which are confirmed by XRD, Raman, TG, SEM, TEM, and XPS analyses. The battery performance reveals that the SnO2/TiO2@CNFs-1.5:1 (1.5:1 denotes the mole ratio of SnO2 to TiO2 in the carbon nanofibers) electrode displays the optimal electrochemical properties among the whole samples, which can deliver the initial charge and discharge specific capacity of 1061.2 and 1494.8 mAh/g with a coulombic efficiency of 71.0% at 100 mA/g, and exhibit a remarkable specific capacity of 766.1 mAh/g after 200 cycles. Moreover, the SnO2/TiO2@CNFs-1.5:1 electrode displays a high pseudocapacitive contribution of 73.9% at the scan rate of 2 mV/s and the lithium ion diffusion coefficient of approximately 1.20 × 10−15 cm2 s−1. The excellent electrochemical performance of the SnO2/TiO2@CNFs-1.5:1 electrode is closely correlated with the synergetic effect of the proper amount of TiO2 that enhances the electrochemical stability of the electrode and provides fractional capacity, and the flexible and conductive carbon nanofiber matrix that accommodates volume changes and increases overall electronic conductivity. The detailed investigations of the as-prepared electrode materials by a facile electrospinning process may pave possible instructions for the next generation SnO2-based anodes and other related electrospun anodes for the energy storage device.