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Homogenous ultra-fine SnO 2 /TiO 2 particles encapsulated into carbon nanofibers (SnO 2 /TiO 2 @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 SnO 2 /TiO 2 @CNFs-1.5:1 (1.5:1 denotes the mole ratio of SnO 2 to TiO 2 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 SnO 2 /TiO 2 @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 SnO 2 /TiO 2 @CNFs-1.5:1 electrode is closely correlated with the synergetic effect of the proper amount of TiO 2 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 SnO 2 -based anodes and other related electrospun anodes for the energy storage device. [ABSTRACT FROM AUTHOR]

• The Am-SnO 2 @P-C powders are synthesized through phase separation and heat treatment. • The differences of amorphous and crystalline SnO 2 based electrodes are investigated. • The porous carbon matrix will improve the structural stability of electrodes. • The Am-SnO 2 @P-C electrode exhibits excellent cycling stability and rate capability. Amorphous SnO 2 nanoparticles embedded into a three-dimensional porous carbon matrix labeled as Am-SnO 2 @P-C are precisely customized through a phase separation process of tin salts and polyacrylonitrile/polyvinylpyrrolidone/ N, N -dimethylformamide polymer mixed solution with the presence of deionized water and combining with heat treatments. The targeted composite powders are characterized by X-ray diffraction, X-ray photoelectron spectroscope, transmission electron microscope, and scanning electron microscope, in which amorphous SnO 2 nanoparticles with ultrafine diameters are uniformly distributed across the three-dimensional porous carbon matrix. The Am-SnO 2 @P-C composite electrode can deliver an initial discharge and charge specific capacity of 1557.6 and 1194.4 mAh/g with an initial coulombic efficiency of 76.7 % at 100 mA/g, and the discharge specific capacity can be retained at 886.4 mAh/g after 200 cycles. Moreover, the Am-SnO 2 @P-C composite electrode also exhibits great rate capability, in which the electrode can deliver a reversible capacity of 581.1 mAh/g at the current density as high as 1.0 A/g with a capacity retention of 92.8 % after 500 cycles. Furthermore, the kinetics investigations of pseudocapacitive contributions and electrochemical impedance spectroscopy on the as-prepared composite electrodes demonstrate the fast electrochemical kinetics of the Am-SnO 2 @P-C electrode due to the synergistic effect of the ultrafine size of amorphous SnO 2 nanoparticles and the porous carbon matrix. Those findings and understandings of the SnO 2 based electrodes may offer some a prospective strategy of the metal-oxide based anodes for lithium-ion batteries in the field of energy storages. [Display omitted]. [ABSTRACT FROM AUTHOR]