Self-Supporting Hybrid Fiber Mats of CuP-CoP/N-C Endowed with Enhanced Lithium/Sodium Ions Storage Performances.

Recently, CuP has been targeted as an alternative anode material for alkali-metal-ion batteries because of their safety potential and high volumetric capacity. However, designing a high-rate CuP electrode with long durability is still faced with huge challenges. Here, we report a self-supporting three-dimensional (3D) composite of CuP and CoP interconnected by N-doped C fibers (CuP-CoP/N-C). The advanced 3D structure not only provides fast reaction kinetics but also improves the structural stability, leading to excellent rate capability and long-term cycling stability, and pseudocapacitance behavior is also beneficial to the high rate performance. Additionally, the synergistic effects between CuP, CoP, and N-doped carbon can increase the electrical conductivity and active sites, ensuring more ion storage. The CuP-CoP/N-C anode for lithium-ion batteries delivers high discharge capacity, superior rate performance, and ultralong lifespan over 2000 cycles accompanied by a stable capacity of around 316.9 mAh/g at 5 A/g. When the 3D structured material works in sodium-ion batteries, it also displays improved electrochemical performance. Our method provides a new insight to design advanced metal phosphides anodes for energy storage devices.