Uniform integration of amorphous SnO2 nanoparticles encapsulated into the carbon matrix as enhanced electrochemical performance anodes for lithium-ion batteries

Amorphous SnO2 nanoparticles uniformly embedded into the carbon matrix (Am-SnO2@C) are prepared by simple phase separation and heat treatments. The Am-SnO2@C composite powders are characterized by X-ray diffraction, X-ray photoelectron spectroscope, and high-resolution-transmission electron microscope, which confirm the amorphous phase and uniform distribution of the SnO2 nanoparticles in the carbon matrix. In addition, the influences of different loadings of SnO2 in the quantitative amount of carbon are thoroughly investigated by just altering the addition of the tin precursor, and the Am-SnO2@C-5 composite electrode displays the optimal electrochemical behaviors when the content of the tin precursor is precisely controlled at 5 mmol. The Am-SnO2@C-5 composite electrode can deliver the discharge/charge specific capacity of 1243.9/940.3 mAh/g with coulombic efficiency of 75% and maintain the discharge specific capacity of 643.1 mAh/g at 100 mA/g after 100 cycles. Moreover, the composite electrode also demonstrates great rate capability with the discharge specific capacity of 410.1 and 286.6 mAh/g at 1.0 and 2.0 A/g, respectively. The improved electrochemical performance of the Am-SnO2@C-5 electrode may be attributed to the fact that the proper active materials are evenly encapsulated into the carbon matrix and that the amorphous nature of SnO2 with ultrafine diameter can offer reduced volume change effect and fast reaction kinetics. The feasible preparation processes of the SnO2/C-based composite electrodes may provide a prospective strategy for the metal oxide-based anodes for lithium-ion batteries.