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 perfo...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.展开更多
基金supported by the National Key Research and Development Program of China(2016YFA0202603)the National Basic Research Program of China(2013CB934103)+4 种基金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)
文摘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.
