Few-layer graphene-encapsulated amorphous Sn4P3-P: A high-capacity and long-cycle-life anode for lithium-ion batteries

Metal phosphides are promising high-capacity anode materials for lithium-ion batteries (LIBs), yet their practical application is limited by capacity degradation and sluggish reaction kinetics. Here, we develop a plasma-assisted ball milling strategy to synthesize amorphous Sn 4 P 3 -phosphorus composites encapsulated in few-layer graphene (Sn 4 P 3 -P@FLG). This method simultaneously achieves in-situ decomposition of SnP 3 into Sn 4 P 3 and phosphorus and exfoliates expanded graphite into ultrathin FLG (3∼5 layers). The FLG coating enhances electronic conductivity and accommodates volume variations, while the phosphorus matrix suppresses Sn coarsening, collectively ensuring stable conversion reversibility. The optimized Sn 4 P 3 -P@FLG delivers an impressive initial reversible capacity of 1356.2 mAh g -1 at 0.1 A g -1 , with coulombic efficiency of 89.1 %. It exhibits exceptional long-term cyclability 1 A g -1 , retaining 92 % capacity (1125.8 mAh g -1 ) after 400 cycles. Furthermore, a full cell paired with commercial LiFePO 4 maintains 86.1 % capacity (882.4 mAh g -1 ) after 150 cycles at 1 A g -1 , demonstrating practical viability. The high electrochemical performance demonstrates the potential of Sn 4 P 3 -P@FLG as a promising anode material for LIBs.