Innovative Mn_(3-x)O_(4-y)@NCA design:Leveraging Mn/O vacancies and amorphous architecture for enhanced sodium-ion storage  

作　　者：Kaijun Xie Xin Liu Kai Xia Lipeng Diao Ping Lu Mengmeng Wang Long Fang Yihui Zou Dongjiang Yang Xiaodong Zhang 

机构地区：[1]College of Chemistry and Chemical Engineering,College of Environmental Science and Engineering,State Key Laboratory of Bio-fibers and Eco-textiles,Shandong Collaborative Innovation Center of Marine Biobased Fibers and Ecological Textiles,Institute of Marine Biobased Materials,Qingdao University,Qingdao 266071,Shandong,China [2]Institute of Micro/Nano Materials and Devices,Ningbo University of Technology,Ningbo 315211,Zhejiang,China

出　　处：《Journal of Energy Chemistry》2024年第10期747-756,I0015,共11页能源化学（英文版）

基　　金：supported by the National Natural Science Foundation of China (22278231,22005165 and 22376110);the Natural Science Foundation Project of Shandong Province (ZR2022MB092 and ZR2023ME098);the Taishan Scholar Program (ts201712030)。

摘　　要：Manganese-based oxide electrode materials suffer from severe Jahn-Teller(J-T)distortion,leading to severe cycle instability in sodium ion storage.However,it is difficult to adjust the electron at d orbitals exactly to a low spin state to eliminate orbital degeneracy and suppress J-T distortion fundamentally.This article constructed concentration-controllable Mn/O coupled vacancy and amorphous network in Mn_(3)O_(4) and coated it with nitrogen-doped carbon aerogel(Mn_(3-x)O_(4-y)@NCA).The existence of Mn/O vacancies has been confirmed by scanning transmission electron microscopy(STEM)and positron annihilation lifetime spectroscopy(PALS).Atomic absorption spectroscopy(AAS)and X-ray photoelectron spectroscopy(XPS)determine the most optimal ratio of Mn/O vacancies for sodium ion storage is 1:2.Density functional theory(DFT)calculations prove that Mn/O coupled vacancies with the ratio of 1:2could exactly induce a low spin states and a d~4 electron configuration of Mn,suppressing the J-T distortion successfully.The abundant amorphous regions can shorten the transport distance of sodium ions,increase the electrochemically active sites and improve the pseudocapacitance response.From the synergetic effect of Mn/O coupled vacancies and amorphous regions,Mn_(3-x)O_(4-y)@NCA exhibits an energy density of 37.5 W h kg^(-1)and an ultra-high power density of 563 W kg^(-1)in an asymmetric supercapacitor.In sodium-ion batteries,it demonstrates high reversible capacity and exceptional cycling stability.This research presents a new method to improve the Na^(+)storage performance in manganese-based oxide,which is expected to be generalized to other structural distortion.

关 键 词：Manganese-based metal oxide Concentration-controllable Mn/O coupled vacancies Amorphous network Sodium ion supercapacitor Sodium ion battery 

分 类 号：TB34[一般工业技术—材料科学与工程] TM912[电气工程—电力电子与电力传动]