The improved anode performance enabled by Ni₂P@C embedded in echinus-like porous carbon for lithium-ion battery

Nickel phosphides (Ni₂P) have been proposed as advanced anode materials for a lithium-ion battery (LIB) due to its high capacity and electrochemical activity. However, the large volume expansion and poor cycling stability limit the practical applications of a Ni₂P based LIB. In this work, we report a one-step strategy to prepare Ni₂P@C nanoparticles embedded in echinus-like porous carbon (Ni₂P@C@EPC) as a promising anode for LIB. It is demonstrated that the Ni₂P@C@EPC corresponds the hexagonal Ni₂P phase very well. The Raman spectrum indicates that the defective carbon is dominant in Ni₂P@C@EPC. Moreover, Ni₂P@C@EPC possesses a high specific surface area of 372.953 cm² · g^-1 with an average pore size of 6.496 nm. Remarkably, the EPC plays a significant role in realizing high and stable performance by confining the reaction between Ni₂P and Li⁺, facilitating Li⁺ diffusion mobility and inhibiting the volume change in charge/discharge. As a result, the Ni₂P@C@EPC delivers a high specific capacity of 807.7 mAh · g^-1 at 0.2 A · g^-1, excellent rate capability (592.1, 455.9, 346.1, 236.4 and 160.69 mAh · g^-1 at 0.1, 0.2, 0.5, 1.0 and 2.0 A · g^-1), and long cycling stability (464.8 mAh · g^-1 at 0.2 A · g^-1 after 100 cycles). Moreover, the structure evolution upon cycling as well as electrochemical analysis has verified the superiority of Ni₂P@C@EPC anode.