Extending the solid solution range of sodium ferric pyrophosphate:Off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)as a novel cathode for sodium‐ion batteries  

作　　者：Xiang jun Pu Kunran Yang Zibing Pan Chunhua Song Yangyang Lai Renjie Li Zheng‐Long Xu Zhongxue Chen Yuliang Cao 

机构地区：[1]Hubei Key Laboratory of Electrochemical Power Sources,College of Chemistry and Molecular Sciences,Wuhan University,Wuhan,China [2]Key Laboratory of Hydraulic Machinery Transients,Ministry of Education,School of Power and Mechanical Engineering,Wuhan University,Wuhan,China [3]School of Chemistry and Chemical Engineering,Jiangsu University of Technology,Changzhou,Jiangsu,China [4]Zonergy Corporation,Zigong,Sichuan,China [5]Department of Industrial and Systems Engineering,The Hong Kong Polytechnic University,Hung Hom,Hong Kong SAR,China

出　　处：《Carbon Energy》2024年第4期128-139,共12页碳能源（英文）

基　　金：National Natural Science Foundation of China,Grant/Award Numbers:21972108,U20A20249,U22A20438;Changzhou Science and Technology Bureau,Grant/Award Number:CM20223017;Innovation and Technology Commission(ITC)of Hong Kong,The Innovation&Technology Fund(ITF)with Project No.ITS/126/21。

摘　　要：Iron‐based pyrophosphates are attractive cathodes for sodium‐ion batteries due to their large framework,cost‐effectiveness,and high energy density.However,the understanding of the crystal structure is scarce and only a limited candidates have been reported so far.In this work,we found for the first time that a continuous solid solution,Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2)(0≤α≤1,could be obtained by mutual substitution of cations at center‐symmetric Na3 and Na4 sites while keeping the crystal building blocks of anionic P_(2)O_(7) unchanged.In particular,a novel off‐stoichiometric Na_(3)Fe(2.5)(P_(2)O_(7))_(2)is thus proposed,and its structure,energy storage mechanism,and electrochemical performance are extensively investigated to unveil the structure–function relationship.The as‐prepared off‐stoichiometric electrode delivers appealing performance with a reversible discharge capacity of 83 mAh g^(−1),a working voltage of 2.9 V(vs.Na^(+)/Na),the retention of 89.2%of the initial capacity after 500 cycles,and enhanced rate capability of 51 mAh g^(−1)at a current density of 1600 mA g^(−1).This research shows that sodium ferric pyrophosphate could form extended solid solution composition and promising phase is concealed in the range of Na_(4−α)Fe_(2+α)_(2)(P_(2)O_(7))_(2),offering more chances for exploration of new cathode materials for the construction of high‐performance SIBs.

关 键 词：extending solid‐solution range off‐stoichiometric Na_(3)Fe_(2.5)(P_(2)O_(7))_(2) sodium‐ion batteries structure-function relationship 

分 类 号：TM912[电气工程—电力电子与电力传动]