Engineering ultra-small tin phosphide encapsulated in 3D phosphorous-doped porous carbon nanosheets as high-performance anodes for lithium-ion batteries

Transition-metal phosphides (TMPs) with high theoretical specific capacity and appropriate reaction potential have been recognized as prospective anode materials for lithium-ion batteries (LIBs). However, the practical application is still hindered by the inferior rate capability and worse cycling stability, which is mainly arising from large volume variations and inferior electric conductivities of TMPs. Herein, ultra-small Sn4P3 particles are fully embedded into three-dimensionally interconnected P-doped porous carbon nanosheets (Sn4P3/P-C@CNs), which is fabricated by a feasible and environmentally friendly synthesis strategy with phytic acid as phosphorus source. The ultra-small Sn4P3 particles and the conductive P-doped 3D carbon backbone is advantage to alleviate the volume changes of Sn4P3 nanoparticles, reduce side reaction with electrolyte and promote the transfer of ions/electrons, leading to a significant improvement in electrochemical performance. Consequently, the Sn4P3/PC@CNs composite electrode delivers a high reversible capacity of 770 mA h g-1 at 0.1 A/g upon 100 cycles, and exhibits 717 mA h g-1 at 1 A/g after 1000 loops. The lithium storage mechanism is investigated by density functional theory calculations. This research could offer a sensible and facile design strategy for TMPs-based electrode materials and make it hopeful for the applications in next-generation high-energy-density LIBs.