LiFe_1-xMn_xPO₄/C COMPOSITE AS CATHODE MATERIAL FOR LITHIUM ION BATTERY

Abstract

LiFe 1-x Mn x PO 4/ C composites were prepared as cathode material for lithium ion battery via solid-state reaction and using glucose as reducing agent and carbon source. The crystal structure and morphology were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The resultant samples were pure olivine compounds with an orthorhombic structure. Their electrochemical performance was studied by galvanostatic charge–discharge test and cyclic voltammetry. The results showed that the sample LiFe0.8Mn0.2PO4/C with an average particle size of 400 nm exhibited the largest discharge capacity of 150 mAh g-1, excellent reversibility of charge–discharge and high capacity retention of 97% after a 50-cycle CV scanning. The improved electrical conductivity corresponding to the fine carbon layer around the LiFe0.8Mn0.2PO4 individual particle can be responsible for all these excellent electrochemical performance.

Improving Electrochemical Properties of LiCoPO4 by Mn Substitution: A Case Research on LiCo0.5Mn0.5PO4

“…Similar scenario was reported by Huang et al, who found that Mn doping could remarkably reduce the size of Zn 1−x Mn x S nanorods under hydrothermal condition. Kinetically, Mn substitution not only reduces the particle sizes and can enhance lattice conductance, 10,11,19 but also generates larger diffusion channels due to expanded unit cell, resulting in a higher Li diffusitivity. a new couple due to Mn 2+ /Mn 3+ emerges at 4.35/4.04 V. It is worth noting that the peaks from LiCo 0.5 Mn 0.5 PO 4 are more symmetric in shape and higher in intensity than those from the pure cobalt compound, manifesting better kinetics and reversibility.…”

“…1 Among them, LiCoPO 4 has recently received peculiar attention due to its high redox potential of 4.8 V (vs. Li + /Li, unless otherwise stated) and thus high energy density of 800 Wh kg −1 , which is essential for batteries to be used in compact energy storage systems. [6][7][8][9][10] Particularly, substitution of electrochemically active cations (Fe 2+ , Mn 2+ , etc.) [2][3][4][5] Various strategies have been developed to improve the electrochemical activity of LiCoPO 4 , including carbon coating, size reducing, and substitution of exotic ions.…”