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• 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]