Hollow Ni/NiO@N-doped porous carbon for lithium ion battery anode based on dual-buffering strategy

As a promising anode material of lithium-ion batteries (LIBs), the poor electrical conductivity and severe volume expansion during cycling of nickel oxide (NiO) greatly limit its practical application. Here, a hollow nitrogen-doped porous carbon-loaded hollow Ni/NiO nanocomposite (Ni/NiO@HNC) was obtained by introducing Ni ²⁺ into hollow covalent organic framework (HCOF) and then calcining the Ni ²⁺/HCOF. The as-prepared Ni/NiO is nanoscale and hollow, which effectively accommodates the expanded volume of NiO. Hollow nitrogen-doped porous carbon (HNC) obtained from HCOF can further accommodate the expanded volume of NiO. The residual Ni and HNC can improve the electrical conductivity of Ni/NiO@HNC greatly. The regular pores of HNC inherited from HCOF facilitate the Li ⁺ transfer. Thus, the Ni/NiO@HNC-2 composites exhibited outstanding cycle stability and rate performance when utilized as anode materials in LIBs. Even after 200 cycles at 0.1 A g ⁻¹, the capacity was still kept at 695.1 mAh g ⁻¹. The work provides an idea to prepare LIBs anodes based on dual-buffering strategy.