从电负性角度选择Cu^(2+)插层:提高水系锌离子电池δ-MnO_(2)正极材料的循环稳定性和倍率性能  

Selection of Cu^(2+)for intercalation from the electronegativity perspective:Improving the cycle stability and rate performance ofδ-MnO_(2)cathode material for aqueous zinc-ion batteries

作　　者：刘振华 刘彦鹏 张亚男 刘晓莉 闫德 黄娟娟 彭尚龙 Zhenhua Liu;Yanpeng Liu;Yanan Zhang;Xiaoli Liu;De Yan;Juanjuan Huang;Shanglong Peng(National&Local Joint Engineering Laboratory for Optical Conversion Materials and Technology,School of Materials&Energy,Lanzhou University,Lanzhou 730000,China)

机构地区：[1]National&Local Joint Engineering Laboratory for Optical Conversion Materials and Technology,School of Materials&Energy,Lanzhou University,Lanzhou 730000,China

出　　处：《Science China Materials》2023年第2期531-540,共10页中国科学（材料科学（英文版）

基　　金：supported by Gansu Provincial Natural Science Foundation of China(17JR5RA198 and 21JR7RA470);the Cooperation Project of Gansu Academy of Sciences(2020HZ-2);the Fundamental Research Funds for the Central Universities(lzujbky-2018-119,lzujbky-2018-ct08,and lzujbky-2019-it23);the Key Areas Scientific and Technological Research Projects in Xinjiang Production and Construction Corps(2018AB004);Hubei University of Arts and Science(2020kypytd002);Xiangyang Science and Technology Research and Development(2020YL09)。

摘　　要：离子插层已成为提高δ-MnO_(2)作为水系锌离子电池正极材料的循环稳定性和倍率性能的有效策略,但在实践中离子的选择似乎相当随意.本工作选择Cu^(2+)插层δ-MnO_(2),因为Cu^(2+)和Zn^(2+)具有相似的直径,但Cu^(2+)的电负性(1.359)略高于Zn^(2+)(1.347).因此,Cu^(2+)与MnO_(2)晶格具有更强的相互作用,并且在Zn^(2+)和H+的嵌入/脱出循环期间可保持稳定.Cu掺杂的δ-MnO_(2)(CMO)生成了Cu–O键,其电化学性能得到了较大的改善.在2 A g^(-1)的高电流密度下循环600次后,CMO表现出出色的循环稳定性和100%的容量保持率,而原始δ-MnO_(2)的容量保持率仅为23%.当电流密度从0.2增加到2.0 A g^(-1)时,CMO还表现出优异的倍率性能,容量保持率为72%,远高于原始δ-MnO_(2)(32%).由于Cu^(2+)比Zn^(2+)具有更大的电负性,因此Cu–O键作为稳定的“结构之柱”提高了CMO的循环稳定性.Cu^(2+)掺杂还提高了CMO的电子电导率和离子电导率,降低了H+和Zn^(2+)在电极/电解质界面的电荷转移电阻,从而提高了其倍率性能.这项工作为使用插层策略提高电池电化学性能提供了新的见解.Ion intercalation is an effective strategy for improving the cycle stability and rate performance ofδ-MnO_(2)as a cathode material for aqueous zinc-ion batteries.However,in practice,ion selection appears rather arbitrary.In this work,Cu^(2+)was chosen forδ-MnO_(2)intercalation because although Cu^(2+)and Zn^(2+)have similar diameters,Cu^(2+)has a slightly higher electronegativity(1.359)than Zn^(2+)(1.347).Therefore,Cu^(2+)has a stronger interaction with the MnO_(2)lattice than Zn^(2+)and can be stable during the intercalation/deintercalation of Zn^(2+)and H+.Results showed that the performance of Cu-dopedδ-MnO_(2)(CMO)was greatly improved.Moreover,at the high current density of 2 A g^(-1),CMO achieved excellent cycle stability with 100%capacity retention after 600 cycles,whereas pristineδ-MnO_(2)exhibited only 23%capacity retention.When the current density was increased from 0.2 to 2.0 A g^(-1),the CMO electrode also delivered remarkable rate performance with 72%capacity retention,which was considerably higher than the 32%capacity retention demonstrated by pristineδ-MnO_(2).Given that Cu^(2+)has a greater electronegativity than Zn^(2+),the Cu–O bond formed in CMO acted as a stable structural column and greatly improved the stability of CMO.Cu^(2+)doping also increased the electronic conductivity and ionic conductivity of CMO and reduced the charge transfer resistance of H+and Zn^(2+)at the electrode/electrolyte interface,which improved the rate performance of CMO greatly.This work provides new insights into intercalation strategies to improve the electrochemical performance of batteries.

关 键 词：倍率性能 正极材料 锌离子电池 循环稳定性 离子电导率 电子电导率 电化学性能 电负性 

分 类 号：O646[理学—物理化学] TM912[理学—化学]