Novel MOF shell-derived surface modification of Li-rich layered oxide cathode for enhanced lithium storage  

作　　者：Zhitong Xiao Jiashen Meng Qi Li Xuanpeng Wang Meng Huang Ziang Liu Chunhua Han Liqiang Mai 

机构地区：[1]State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, International School of Materials Science and Engineering, Wuhan University of Technology [2]Department of Chemistry, University of California

出　　处：《Science Bulletin》2018年第1期46-53,共8页科学通报（英文版）

基　　金：supported by the National Key Research and Development Program of China(2016YFA0202603);the National Basic Research Program of China(2013CB934103);the Programme of Introducing Talents of Discipline to Universities(B17034);the National Natural Science Foundation of China(51521001);the National Natural Science Fund for Distinguished Young Scholars(51425204);the Fundamental Research Funds for the Central Universities(WUT:2016III001 and 2016-YB-004);financial support from China Scholarship Council(201606955096)

摘　　要：Li-rich layered oxide materials have attracted increasing attention because of their high specific capacity(>250 mAh g^(-1)). However, these materials typically suffer from poor cycling stability and low rate performance. Herein, we propose a facile and novel metal-organic-framework(MOF) shell-derived surface modification strategy to construct NiCo nanodots decorated(~5 nm in diameter) carbon-confined Li_(1.2)Mn_(0.54) Ni_(0.13)Co_(0.13)O_2 nanoparticles(LLO@C&NiCo). The MOF shell is firstly formed on the surface of as-prepared Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_2 nanoparticles via low-pressure vapor superassembly and then is in situ converted to the NiCo nanodots decorated carbon shell after subsequent controlled pyrolysis.The obtained LLO@C&NiCo cathode exhibits enhanced cycling and rate capability with a capacity retention of 95% after 100 cycles at 0.4 C and a high capacity of 159 mAh g^(-1) at 5 C, respectively, compared with those of LLO(75% and 105 mAh g^(-1)). The electrochemical impedance spectroscopy and selected area electron diffraction analyses after cycling demonstrate that the thin C&NiCo shell can endow LLO with high electronic conductivity and structural stability, indicating the undesired formation of the spinel phase initiated from the particle surface is efficiently suppressed. Therefore, this presented strategy may open a new avenue on the design of high-performance electrode materials for energy storage.Li-rich layered oxide materials have attracted increasing attention because of their high specific capacity（〉250 mAh g-1）. However, these materials typically suffer from poor cycling stability and low rate performance. Herein, we propose a facile and novel metal-organic-framework（MOF） shell-derived surface modification strategy to construct NiCo nanodots decorated（5 nm in diameter） carbon-confined Li1.2Mn0.54 Ni0.13Co0.13O2 nanoparticles（LLO@C＆NiCo）. The MOF shell is firstly formed on the surface of as-prepared Li1.2Mn0.54Ni0.13Co0.13O2 nanoparticles via low-pressure vapor superassembly and then is in situ converted to the NiCo nanodots decorated carbon shell after subsequent controlled pyrolysis.The obtained LLO@C＆NiCo cathode exhibits enhanced cycling and rate capability with a capacity retention of 95% after 100 cycles at 0.4 C and a high capacity of 159 mAh g-1 at 5 C, respectively, compared with those of LLO（75% and 105 mAh g-1）. The electrochemical impedance spectroscopy and selected area electron diffraction analyses after cycling demonstrate that the thin C＆NiCo shell can endow LLO with high electronic conductivity and structural stability, indicating the undesired formation of the spinel phase initiated from the particle surface is efficiently suppressed. Therefore, this presented strategy may open a new avenue on the design of high-performance electrode materials for energy storage.

关 键 词：Surface modification MOF shell Li-rich layered oxide Lithium-ion battery 

分 类 号：TM912[电气工程—电力电子与电力传动]