Constructing fast-ion-diffusion cathode-electrolyte-interphase to improve LiNi0.8Co0.1Mn0.1O2 cathode cyclic stability with composite polymer conductors

Abstract

As one of the mainstream cathode materials used in power battery, it’s necessary for the LiNixCoyMn1-x-yO2 (NCM) to perform fast charge and discharge capabilities. However, the unstable cathode-electrolyte-interphase (CEI) at high charging/discharging rates causes cycling performance to degrade rapidly. Modified polyaniline (PANI) and polyethylene glycol (PEG) are adsorbed on layer-structured Ni-rich cathode, forming cathode-electrolyte-interphase CEI film with high electro-chemical stability and mechanical strength layer by coordinating interaction of hydrogen bonds with transition metals. When the carbon nanotubes (CNTs) or the -SO2F functional group in bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) enters PANI skeleton, the composition, morphology and thickness of CEI film would be influenced by the CNTs or -SO2F groups. The improved interface would enhance the cathode-electrolyte interface stability by providing a steady channel for Li+ transport. Hence, the optimized CEI film effectively inhibit the occurrence of side reactions, and the capacity retention of NCM@PANIPEG/LiTFSI||Li cells has been improved from ∼ 55% to ∼ 77% at 45 °C and 2.7–4.3 V (vs. Li+/Li) in 100 cycles at 1 C. This low cost and straightforward preparation process exhibit great application prospects in future industrial applications.