Tuning electronic structure ofδ-MnO_(2) by the alkali-ion(K,Na,Li)associated manganese vacancies for high-rate supercapacitors  

作　　者：Lengyuan Niu Lijin Yan Zhengwei Lu Yinyan Gong Taiqiang Chen Can Li Xinjuan Liu Shiqing Xu 

机构地区：[1]College of Optical and Electronic Technology,China Jiliang University,Hangzhou 311018,Zhejiang,China [2]College of Materials and Chemistry,China Jiliang University,Hangzhou 310018,Zhejiang,China

出　　处：《Journal of Energy Chemistry》2021年第5期245-258,共14页能源化学（英文版）

基　　金：supported by Zhejiang Provincial Natural Science Foundation of China under Grant No.LQ18E030005,LY18E060005,LY19E020006,LY18E020007;National Natural Science Foundation of China(No.51902301)。

摘　　要：Cation vacancies can bring numerous surprising characters due to its multifarious electron and orbit distribution.In this work,d-MnO_(2) with alkali-ion(K,Na,Li)associated manganese(Mn)vacancies is fabricated by a simple hydrothermal reaction,and the correlation between their electronic structure and pseudocapacitance are systematically investigated.FESEM/TEM images have shown that the morphology of MnO_(2) is obviously changed after the introducing of cation vacancies.The position of alkali-ion in MnO_(2) structure can be controlled by adjusting the ion concentration.XRD patterns and Raman spectra demonstrate that the alkali-ion is embedded in Mn vacancies at low concentration,while entered the interlayer of MnO_(2) at high concentration.The existence of Mn vacancies will resulting in the distortion of neighboring atoms,leading to the electronic delocalization,and thus enhancing the conductivity,pseudocapacitance and rate capability of MnO_(2).Accordingly,the specific capacitances of optimized 0.4 KMO,0.4 NaMO and 0.4 LiMO samples are enhanced about 1.9,1.6 and 1.6 times compared to pure MnO_(2).Meanwhile,the rate performance has also been improved about 76%,46%and 42%,respectively.Theoretical calculations further confirm that the Mn vacancies can generate additional occupancy states and cause an increase in carrier concentration,which will improve the conductivity and further boost the pseudocapacitance of MnO_(2).This result open up a promising approach to explore active and durable electrode materials.

关 键 词：SUPERCAPACITOR Manganese oxide Manganese vacancies PSEUDOCAPACITANCE 

分 类 号：TQ137.12[化学工程—无机化工] TM53[电气工程—电器]