蛋黄-壳NiCoP@N-C材料的制备及其储钠特性研究

Preparation of yolk-shell structured NiCoP@N-C material for sodium ion batteries

NiCo基磷化物因其优异的导电性和较高的理论容量,被认为是最有潜力的钠离子电极材料.然而,NiCo基磷化物在钠离子嵌入/脱出时会发生严重的体积应变,导致NiCo基磷化物的倍率特性降低,循环稳定性大幅度衰减.针对这些问题,采用多巴胺包覆-煅烧-磷化处理法制备了蛋黄-壳结构的NiCoP@N-C材料,在该材料中,氮掺杂碳层有效地改善了电极材料固有的电导率和结构完整性;独特的蛋黄-壳结构显著减缓了在钠离子嵌入/脱出过程中的体积膨胀.当NiCoP@N-C作为钠离子电池负极材料时表现出优异的电化学性能.在0.1 A·g^(-1)电流密度下,循环100圈后的可逆比容量仍高达462.3 mAh·g^(-1).

NiCo-based phosphides are considered to be the most promising materials for sodium ion electrodes due to their excellent electrical conductivity and high theoretical capacity.However,NiCo-based phosphides undergo severe volume strain during the sodium insertion/extraction processes leading to the reduction of multiplicity characteristics and substantial decay of cycling stability.To address the problems,the yolk-shell structured NiCoP@N-C material was prepared by dopamine coating-calcined-phosphide treatment.In this material,the nitrogen-doped carbon layer effectively improves the conductivity and structural integrity of the electrode material,and the yolk-shell structured NiCoP@N-C material significantly slows down the volumetric expansion during the sodium insertion/extraction processes.When used as an anode material for sodium-ion batteries,the as-obtained NiCoP@N-C exhibits excellent electrochemical performance:the reversible specific capacity was still as high as 462.3 mAh·g^(-1) after 100 cycles at a current density of 0.1 A·g^(-1).