High-rate-induced capacity evolution of mesoporous C@SnO₂@C hollow nanospheres for ultra-long cycle lithium-ion batteries

Dual carbon shells coated SnO₂ hollow nanospheres (C@SnO₂@C) are synthesized as anode material for lithium ion batteries, it delivers an almost constant capacity about 712.6 mAh g⁻¹ after 300th cycles at 200 mA g⁻¹. A capacity recovery (more than 200%) is observed during the high rate (5 A g⁻¹) long cycling process (10000 cycles). The discharge capacity of the C@SnO₂@C electrode is only 194.5 mAh g⁻¹ after 200 cycles. Afterwards the capacity increases gradually until the 3000th cycle up to 500 mAh g⁻¹ and then keeps stable for the subsequent cycles without obvious capacity fading tendency after 10000 cycles. These superior electrochemical performances should be attributed to the synergistic effect between the double carbon coating layers and the refined nanosized SnO₂ nanocrystals. The double carbon coating layer could not only effectively provide buffers against the structural pulverization of electrodes during charge and discharge process through a novel spatial confinement strategy, but also facilitate the diffusion of electrons by enhancing the electronic conductivity. Thus, these benefits from the dually coated structure are able to provide a robust architecture for lithium-ion battery anodes.