材料科学
阴极
兴奋剂
涂层
保形涂层
电导率
碳纤维
阳极
电化学
法拉第效率
热解炭
化学工程
纳米技术
复合材料
电极
光电子学
物理化学
化学
热解
工程类
复合数
作者
Ze‐Rong Deng,Lu‐Lu Zhang,Feng Peng,Liping Wen,Chang Q. Sun,Hong Sun,Xiaoxia Ding,Xuelin Yang
出处
期刊:Small
[Wiley]
日期:2024-03-25
标识
DOI:10.1002/smll.202400149
摘要
Layered Na2FePO4F (NFPF) cathode material has received widespread attention due to its green nontoxicity, abundant raw materials, and low cost. However, its poor inherent electronic conductivity and sluggish sodium ion transportation seriously impede its capacity delivery and cycling stability. In this work, NFPF by Ti doping and conformal carbon layer coating via solid-state reaction is modified. The results of experimental study and density functional theory calculations reveal that Ti doping enhances intrinsic conductivity, accelerates Na-ion transport, and generates more Na-ion storage sites, and pyrolytic carbon from polyvinylpyrrolidone (PVP) uniformly coated on the NFPF surface improves the surface/interface conductivity and suppresses the side reactions. Under the combined effect of Ti doping and carbon coating, the optimized NFPF (marked as 5T-NF@C) exhibits excellent electrochemical performance, with a high capacity of 108.4 mAh g-1 at 0.2C, a considerable capacity of 80.0 mAh g-1 even at high current density of 10C, and a high capacity retention rate of 81.8% after 2000 cycles at 10C. When assembled into a full cell with a hard carbon anode, 5T-NF@C also show good applicability. This work indicates that co-modification of Ti doping and carbon coating makes NFPF achieve high rate and long cycle performance for sodium-ion batteries.
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