Morphology-controlled synthesis of hollow spherical and sea urchin-like CoP/C composites via sodium citrate regulation for pseudocapacitive lithium storage

Transition metal phosphides (TMPs) have emerged as promising high-capacity anode materials for lithium-ion batteries (LIBs). However, their practical application remains constrained by the dual challenges of intrinsic low conductivity and structural degradation during cycling. In this study, CoP/C composites with hollow spherical (denoted as s-CoP/C) and sea urchin-like (u-CoP/C) morphologies were synthesized in a morphology-controlled manner using sodium citrate as a structure directing agent, aiming to elucidate the structure-performance relationship in lithium storage. Systematic characterization reveals the hollow spherical architecture of s-CoP/C effectively enhances charge transfer kinetics and buffered volume variations during cycling, outperforming its u-CoP/C counterpart. As a result, s-CoP/C delivered a stable reversible specific capacity of 527.5 mAh g −1 after 600 cycles at 1 A g −1 . Kinetic analysis demonstrates a dominant pseudocapacitive contributes of 85.6 % at a sweep rate of 1.5 mV s −1 . In addition, robust interfacial chemical bonding between CoP and carbon matrix through C–P and Co– O –C linkages ensures structural integrity during prolonged cycling. This work establishes a synergistic strategy combining morphological engineering with interfacial optimization to develop durable TMP-based anodes for advanced energy storage systems.