Elevated Electrochemical Performance of LiNi0.1Mg0.1Co0.8O₂ and LiFePO₄ Cathodes with Tris(2,2,2-trifluoroethyl) Phosphite as an Efficient Electrolyte Additive.

Abstract

The significant role of Tris(2,2,2-trifluoroethyl) phosphite (TTFP) as an efficient additive during cycling of the layered nanostructured LiNi_0.1Mg_0.1Co_0.8O₂ and olivine LiFePO₄ cathode materials in EC/DMC and 1M LiPF₆ electrolyte for Li-ion battery are extensively investigated in this work. The electrochemical characterization techniques such as cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy show that TTFP improves cycling stability and reduces the irreversible capacity of LiNi_0.1Mg_0.1Co_0.8O₂ and LiFePO₄ electrodes. Also, the presence of TTFP in electrolyte solution reduces the impedance in LiNi_0.1Mg_0.1Co_0.8O₂ and LiFePO₄ cathode materials at room temperature. A family of Nyquist plots was obtained from LiNi_0.1Mg_0.1Co_0.8O₂ and LiFePO₄ electrodes for various potentials during the course of charging. The addition of TTFP in the electrolyte reduces the surface impedance of lithiated LiNi_0.1Mg_0.1Co_0.8O₂ and LiFePO₄ which can be attributed to the reaction of the additive on the electrode's surface. Also, the presence of the additive TTFP in LiNi_0.1Mg_0.1Co_0.8O₂ and LiFePO₄ cell enhances the lithium diffusion rate and improves the electronic conductivity of the cathode material.