Lithium-rich layered oxides always suffer from low initial Coulombic efficiency,poor rate capability and rapid voltage fading.Herein,engineering oxygen vacancies in hierarchically Li1.2Mn0.54Ni0.13Co0.13O2 porous micr...Lithium-rich layered oxides always suffer from low initial Coulombic efficiency,poor rate capability and rapid voltage fading.Herein,engineering oxygen vacancies in hierarchically Li1.2Mn0.54Ni0.13Co0.13O2 porous microspheres(L@S)is carried out to suppress the formation of irreversible Li20 during the initial discharge process and improve the Li+diffusion kinetics and structural stability of the cathode mateiral.As a result,the prepared L@S cathode delivers high initial Coulombic efficiency of 92.3%and large specific capacity of 292.6 mA h g^-1 at 0.1 C.More importantly,a large reversible capacity of 222 mA h g^-1 with a capacity retention of95.7%can be obtained after 100 cycles at 10 C.Even cycled at ultrahigh rate of 20 C,the L@S cathode can deliver stable reversible capacity of 153 mA h g^-1 after 100 cycles.Moreover,the full cell using L@S as cathode and Li4 Ti5 O12 as anode exhibits a relatively high reversible capacity of 141 mA h g^-1 with an outstanding voltage retention of 97%after 400 cycles at a large current density of 3 C.These results may shed light on the improvement of electrochemical performances of lithiumrich layered oxides via the multiscale coordinated design based on atomic defects,microstructure and composition.展开更多
基金support from the National Key R&D Program of China(2016YFA0202602 and2016YFA0202604)the National Natural Science Foundation of China(51701169 and 51871188)+2 种基金the Natural Science Foundation of Fujian Province(2017J05087)the Key Projects of Youth Natural Foundation for the Universities of Fujian Province of China(JZ160397)the“Double-First Class” Foundation of Materials and Intelligent Manufacturing Discipline of Xiamen University
文摘Lithium-rich layered oxides always suffer from low initial Coulombic efficiency,poor rate capability and rapid voltage fading.Herein,engineering oxygen vacancies in hierarchically Li1.2Mn0.54Ni0.13Co0.13O2 porous microspheres(L@S)is carried out to suppress the formation of irreversible Li20 during the initial discharge process and improve the Li+diffusion kinetics and structural stability of the cathode mateiral.As a result,the prepared L@S cathode delivers high initial Coulombic efficiency of 92.3%and large specific capacity of 292.6 mA h g^-1 at 0.1 C.More importantly,a large reversible capacity of 222 mA h g^-1 with a capacity retention of95.7%can be obtained after 100 cycles at 10 C.Even cycled at ultrahigh rate of 20 C,the L@S cathode can deliver stable reversible capacity of 153 mA h g^-1 after 100 cycles.Moreover,the full cell using L@S as cathode and Li4 Ti5 O12 as anode exhibits a relatively high reversible capacity of 141 mA h g^-1 with an outstanding voltage retention of 97%after 400 cycles at a large current density of 3 C.These results may shed light on the improvement of electrochemical performances of lithiumrich layered oxides via the multiscale coordinated design based on atomic defects,microstructure and composition.
