Lithium-rich materials possess the ultra-high specific capacity,but the redox of oxygen is not completely reversible,resulting in voltage attenuation and structural instability.A stepwise co-precipitation method is us...Lithium-rich materials possess the ultra-high specific capacity,but the redox of oxygen is not completely reversible,resulting in voltage attenuation and structural instability.A stepwise co-precipitation method is used for the first time in this paper to achieve the control of the two-phase distribution through controlling the distribution of transition metal elements and realize the modification of particle surface structure without the aid of heterologous ions.The results of characterization tests show that the content of LiMO_(2) phase inside the particles and the content of Li_(2)MnO_(3) phase on the surface of the particles are successfully increased,and the surface induced formation of Li_(4)Mn_(5)O_(12) spinel phase or some disorderly ternary.The electrochemical performance of the modified sample is as follows:LR(pristine)shows specific discharge capacity of 72.7 mA·h·g^(−1)after 500 cycles at 1 C,while GR(modified sample)shows specific discharge capacity of 137.5 mA·h·g^(−1) at 1 C,and the discharge mid-voltage of GR still remains above 3 V when cycling to 220 cycles at 1 C(mid-voltage of LR remains above 3 V when cycling to 160 cycles at 1 C).Therefore,deliberately regulating the local state of the two phases is a successful way to reinforced the material structure and inhibition the voltage attenuation.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos. 51972023 and 51572024)
文摘Lithium-rich materials possess the ultra-high specific capacity,but the redox of oxygen is not completely reversible,resulting in voltage attenuation and structural instability.A stepwise co-precipitation method is used for the first time in this paper to achieve the control of the two-phase distribution through controlling the distribution of transition metal elements and realize the modification of particle surface structure without the aid of heterologous ions.The results of characterization tests show that the content of LiMO_(2) phase inside the particles and the content of Li_(2)MnO_(3) phase on the surface of the particles are successfully increased,and the surface induced formation of Li_(4)Mn_(5)O_(12) spinel phase or some disorderly ternary.The electrochemical performance of the modified sample is as follows:LR(pristine)shows specific discharge capacity of 72.7 mA·h·g^(−1)after 500 cycles at 1 C,while GR(modified sample)shows specific discharge capacity of 137.5 mA·h·g^(−1) at 1 C,and the discharge mid-voltage of GR still remains above 3 V when cycling to 220 cycles at 1 C(mid-voltage of LR remains above 3 V when cycling to 160 cycles at 1 C).Therefore,deliberately regulating the local state of the two phases is a successful way to reinforced the material structure and inhibition the voltage attenuation.
