Hydrothermal synthesis of three-dimensional core-shell hollow N-doped carbon encapsulating SnO₂@CoO nanospheres for high-performance lithium-ion batteries

A new three-step route to synthesize three-dimensional (3D) core-shell hollow N-doped carbon encapsulating SnO₂@CoO nanospheres (namely, SCC) is developed. The NH₄F plays a key role for conformal growth to generate Co₃O₄ layers. The polydopamine layer is regarded as carbon and nitrogen source for the formation of N-doped carbon shell which is used as a reductant to convert Co₃O₄ into CoO. Owing to its unique core-shell architectures to provide conductive networks and flexible buffering matrix, the anodic material exhibits prominent lithium storage performance according to high specific capacity (1081 mAh g⁻¹ at 100 mA g⁻¹ for 100 cycles), high rate capacity (803.1 mAh g⁻¹ at 2 A g⁻¹), and good capacity retention (881.7 mAh g⁻¹ at 1 A g⁻¹ for 550 cycles) with consistently high coulombic efficiency.