Ultrafine CoP nanoparticles encapsulated in N/P dual-doped carbon cubes derived from 7,7,8,8-tetracyanoquinodimethane for lithium-ion batteries

The design of electrode materials plays a significant role in achieving the desired electrochemical performance for lithium-ion batteries; the design should provide a fast electronic transport pathway and prevent excessive volume variation. Herein, ultrafine CoP nanoparticles were successfully embedded in a nitrogen-doped carbon cube (NP-CC), which was synthesized from 7,7,8,8-tetracyanoquinodimethane (TCNQ)-derived carbon. CoP@NP-CC was synthesized by the chemical interaction between cobalt iodide and TCNQ, followed by thermal phosphidation. When applied as an anode material for lithium-ion batteries, CoP@NP-CC exhibited outstanding rate capability with a long-term cycling performance. The excellent electrochemical performance is attributed to the monodisperse construction of CoP nanoparticles embedded in NP-CC, which relieved the volume change of CoP nanoparticles and provided a highly conductive matrix. This design of a monodisperse cubic architecture can be extended to other transition-metal-based electrode materials to attain a high performance of lithium-ion batteries.