揭示钠离子电池正极材料Na_(6-2x)Fe_(x)(SO_(4))_(3)(1.5≤x≤2.0)的结构及电化学性质  

Revealing the structural chemistry in Na_(6-2x)Fe_(x)(SO_(4))_(3)(1.5≤x≤2.0)for low-cost and high-performance sodium-ion batteries

作　　者：赵阿龙 汲方杰 刘长禹 张世豪 陈柯安 冯祥明 陈卫华 钟发平 艾新平 杨汉西 方永进 曹余良 Along Zhao;Fangjie Ji;Changyu Liu;Shihao Zhang;Kean Chen;Weihua Chen;Xiangming Feng;Faping Zhong;Xinping Ai;Hanxi Yang;Yongjin Fang;Yuliang Cao(College of Chemistry and Molecular Sciences,Hubei Key Laboratory of Electrochemical Power Sources,Wuhan University,Wuhan 430072,China;College of Chemistry and Molecular Engineering,Zhengzhou University,Zhengzhou 450001,China;National Engineering Research Centre of Advanced Energy Storage Materials,Changsha 410205,China)

机构地区：[1]College of Chemistry and Molecular Sciences,Hubei Key Laboratory of Electrochemical Power Sources,Wuhan University,Wuhan 430072,China [2]College of Chemistry and Molecular Engineering,Zhengzhou University,Zhengzhou 450001,China [3]National Engineering Research Centre of Advanced Energy Storage Materials,Changsha 410205,China

出　　处：《Science Bulletin》2023年第17期1894-1903,共10页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(U20A20249,22209125,and 21972108);the Key Research Program of Hubei Province(2020BAA030)。

摘　　要：铁基硫酸盐聚阴离子材料因其成本低廉、电化学性能优异等优点,是钠离子电池大规模应用最有前景的候选材料之一.尽管Na_(2)Fe_(2)(SO_(4))_(3),Na_(2)Fe_(1.5)(SO_(4))_(3),Na_(2.4)Fe_(1.8)(SO_(4))_(3)和Na_(2.4)Fe_(1.8)(SO_(4))_(3)等Na_(6-2x)Fe_(x)(SO_(4))_(3)(NFSO-x 1.5≤x≤2.0)材料在储钠方面取得了巨大成果,但这些NFSO-x的相和结构特性仍存在争议,难以实现具有最佳电化学性能的纯相材料.本文通过实验方法和密度泛函理论计算研究了6个具有不同x的NFSO-x样品,以分析其相和结构特性.结果表明在NFSO-x的1.6≤x≤1.7区域存在纯相,部分Na离子倾向于占据Fe位点以形成更稳定的框架.NFSO-1.7在NFSO-x样品中表现出最佳的电化学性能,具有高的放电容量(0.1 C时为104.5 mAh g^(-1),接近其理论容量105 mAh g^(-1))、出色的倍率性能(30 C时为81.5 mAh g^(-1)),并在10,000次循环中具有超长的循环稳定性,容量保持率为72.4%.本研究有助于阐明铁基硫酸盐聚阴离子材料的相和结构特征,以促进其在大规模储能中的应用.Fe-based polyanionic sulfate materials are one of the most promising candidates for large-scale applications in sodium-ion batteries due to their low cost and excellent electrochemical performance.Although great achievements have been gained on a series of Na_(6-2x)Fe_(x)(SO_(4))_(3)(NFSO-x,1.5≤x≤2.0)materials such as Na_(2)Fe_(2)(SO_(4))_(3),Na_(2)Fe_(1.5)(SO_(4))_(3),Na_(2.4)Fe_(1.8)(SO_(4))_(3)for sodium storage,the phase and structure characteristics on these NFSO-x are still controversial,making it difficult to achieve phase-pure materials with optimal electrochemical properties.Herein,six NFSO-x samples with varied x are investigated via both experimental methods and density functional theory calculations to analyze the phase and structure properties.It reveals that a pure phase exists in the 1.6≤x≤1.7 region of the NFSO-x,and part of Na ions tend to occupy Fe sites to form more stable frameworks.The NFSO-1.7 exhibits the best electrochemical performance among the NFSO-x samples,delivering a high discharge capacity(104.5 mAh g^(-1)at 0.1 C,close to its theoretical capacity of 105 mAh g^(-1)),excellent rate performance(81.5 mAh g^(-1)at 30 C),and remarkable cycle stability over 10,000 cycles with high-capacity retention of 72.4%.We believe that the results are useful to clarify the phase and structure characteristics of polyanionic materials to promote their application for large-scale energy storage.

关 键 词：钠离子电池 理论容量 电化学性质 放电容量 倍率性能 电化学性能 密度泛函理论计算 聚阴离子 

分 类 号：TM912[电气工程—电力电子与电力传动] TQ131.12[化学工程—无机化工]