Sandwich-like SnO2/Cu@Carbon composites with long-term cycling stability as lithium-ion battery anodes

Tin-based anode materials have emerged as a promising candidate for lithium-ion batteries due to its inexpen-sive cost and high theoretical specific capacity, whereas its potential application is limited by severe capacity attenuation and inferior cycling stability due to the huge volume fluctuation during lithiation/delithiation. Herein, SnO2/Cu@Carbon composite was fabricated to overcome this problem through a facile co-precipitation approach followed by carbon coating. In the as-prepared composite, SnO2 and Cu particles are uniformly embedded in N-doped carbon network matrix. Such unique sandwich-like product can greatly alleviate the large volume expansion and SnO2 aggregation that is conducive to the electron/ion migration, and significantly improve cycling permanence. Therefore, the optimized sample shows impressive long-term stability even at high current density of 1.0 A g-1 (348 mAh g-1 after 1000 loops without obvious capacity decay). Moreover, a comprehensive dynamic analysis of the lithium storage was performed, implying that the increased Li+ diffusion coefficient and pseudocapacitive contribution after cycling may account for the improved electrochemical performances.