Self-Catalyzed Synthesis of Length-Controlled One-Dimensional Nickel Oxide@N-Doped Porous Carbon Nanostructures from...

Transition metal oxides with the merits of high theoretical capacities, natural abundance, low cost, and environmental benignity have been regarded as a promising anodic material for lithium ion batteries (LIBs). However, the severe volume expansion upon cycling and poor conductivity limit their cycling stability and rate capability. To address this issue, NiO embedded and N-doped porous carbon nanorods (NiO@NCNR) and nanotubes (NiO@NCNT) are synthesized by the metal-catalyzed graphitization and nitridization of monocrystalline Ni(II)-triazole coordinated framework and Ni(II)/melamine mixture, respectively, and the following oxidation in air. When applied as an anodic material for LIBs, the NiO@NCNR and NiO@NCNT hybrids exhibit a decent capacity of 895/832 mA h g^-1 at 100 mA g^-1, high rate capability of 484/467 mA h g^-1 at 5.0 A g^-1, and good long-term cycling stability of 663/634 mA h g^-1 at 600th cycle at 1 A g^-1, which are much better than those of NiO@carbon black (CB) control sample (701, 214, and 223 mA h g^-1). The remarkable electrochemical properties benefit from the advanced nanoarchitecture of NiO@NCNR and NiO@NCNT, which offers a length-controlled one-dimensional porous carbon nanoarchitecture for effective e^-/Li⁺ transport, affords a flexible carbon skeleton for spatial confinement, and forms abundant nanocavities for stress buffering and structure reinforcement during discharge/charging processes. The rational structural design and synthesis may pave a way for exploring advanced metal oxide based anodic materials for next-generation LIBs.