Electrochemical properties and performance of a flexible polysiloxane-based ionic conductor as a binder for LiFePO4 cathode

Abstract

Poly(methyl(2-(tris(2-H methoxyethoxy)silyl)ethyl)siloxane)) modified with Si-tripodant centers (2550EO) and integrated amide salt (LiF(SO2CF3)2 (LiTFSI)) has been used as a binding agent in the lithium-ion batteries containing LiFePO4 (LFP). The performance of the cathode produced using 2550EO/LiTFSI was evaluated using X-ray diffraction, scanning electron microscope, and electrochemical measurements. The electrochemical performance of the LFP cathode using 2550EO/LiTFSI was compared to alternative binders, such as Polyvinylidene fluoride (PVDF), Polyethylene oxide (PEO), and 2550EO, at 25 °C and 60 °C, respectively. By using 2550EO/LiTFSI as a binder in LFP/Li battery preparation, the rate capability and cycle stability of the LFP cathode is significantly enhanced. The enhanced performance is attributed to the formation of a thin, solid-electrolyte interface (SEI) on the electrodes, the uniform dispersion of active and conductive materials throughout the electrode, and the adhesion capability of 2550EO#LiTFSI/LFP to the Al current collector, which increases the electronic conductivity of the LFP cathode.