Amorphous SnO2 nanoparticles embedded into a three-dimensional porous carbon matrix as high-performance anodes for lithium-ion batteries

Amorphous SnO2 nanoparticles embedded into a three-dimensional porous carbon matrix labeled as Am-SnO2@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 SnO2 nanoparticles with ultrafine diameters are uniformly distributed across the three-dimensional porous carbon matrix. The Am-SnO2@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-SnO2@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-SnO2@P-C electrode due to the synergistic effect of the ultrafine size of amorphous SnO2 nanoparticles and the porous carbon matrix. Those findings and understandings of the SnO2 based electrodes may offer some a prospective strategy of the metal-oxide based anodes for lithium-ion batteries in the field of energy storages.