Enhanced electrochemical performance and storage mechanism of LiFePO4 doped by Co, Mn and S elements for lithium-ion batteries.

How to improve the diffusion coefficient of Lithium ions in active materials is very necessary, which is responsible for the electrochemical performance. In this present contribution, LiFe 10/12 Co 1/12 Mn 1/12 P 11/12 S 1/12 O 4 (LF(CM)P(S)O) are designed and the stability, lithium ion diffusion rate, lithium intercalation potential, discharge curve, and electronic performances are systematically explored. The LF(CM)P(S)O shows the better stability with the formation energy of 2.01 eV. The lithium ion diffusion barrier of the system is reduced from 1.02 to 0.57 eV after doping, predicting that the lithium ion diffusion rate in LF(CM)P(S)O is 10 orders of magnitude faster than that of intrinsic system. The characteristic transition from p-type to n-type semiconductor is present due to the doping of S, and the doping of Mn and Co leads to the generation of impurity bands and the reduction of band gap from 3.78 to 0.737 eV. The effective mass of electrons in the doped system is 1.59m 0 , much greater than 1m 0 , which is conducive to the improvement of its conductivity. The charge density difference and electron localization function (ELF) demonstrates that the disappearance of electron enrichment and the decrease of the localization are responsible for the rapid migration of the lithium ion. The high operating voltage, charge-discharge platform of 4.7 V and the voltage difference contribute to the promotion of electrochemical performance, which open a window for the commercialization application of Li-ion battery. [ABSTRACT FROM AUTHOR]