ИСТИНА

At the moment, olivine-structured LiFePO4 is one of most studied cathode materials for LIBs. Besides its advantages, such as high theoretical capacity, low cost and excellent cyclability, LiFePO4 has serious drawback – low working potential in comparison with other materials (3.4V vs. Li/Li+). Other olivine LiMPO4 (M=Mn,Co,Ni) materials with higher potential cannot be used in LIBs at the moment, because of low achievable capacity and poor cycle life. Combining different d-metals into the solid solutions with general formula Li(M1,M2,M3)PO4, (М1,2,3 = Fe, Mn, Co) gives opportunity to combine increased working potential, structure stability and good cyclability. Moreover, random distribution of the d-cations in the olivine structure leads to the increasing share of solid solution (or single-phase) mechanism of Li+ (de)intercalation, and therefore considerable improves performance at high cycling rates[1]. Synthesis of LiFe1-x-yMnxCoyPO4 (x=0.5, y=0 and x=y=0.33) cathode materials were performed via solvothermal route; carbon-containing composites were obtained by annealing with glucose in Ar atmosphere (in presence of Ar or Fe getter). Synthesized materials were investigated by XRD, SEM, EDX and ICP-MS. Electrochemical testing was performed using galvanostatic charge/discharge of composites LiFe1-x-yMnxCoyPO4/C. Synthetic route was optimized for all studied compositions; the samples consisted of plate-like crystallite with <100 nm particle size (b-axis) and uniform distribution of d-metalls. Obtained materials were tested under different charge/discharge current loads (C/10-100C) and demonstrated high specific capacity and power – up to 104.5 mAh/g at 50C discharge (44s) and up to 70% theoretical capacity after 100C charge (29s). Lithium (de)intercalation process was investigated using synchrotron XRD and Mossbauer spectroscopy in operando regime; results would be widely discussed in poster presentation. This work was supported by Skolkovo Institute of Science and Technology and Lomonosov Moscow State University Program of Development. 1. Drozhzhin, O. A., et al. Electrochimica Acta, 2016, 191: 149-157.