Optimize two-phase distribution of lithium-rich materials to stabilize structure and suppress voltage attenuation

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.