A multifunctional additive extending the calendar life of Ni-rich cathode-based lithium-ion batteries for electric vehicles

Abstract

Lithium-ion batteries (LIBs) with Ni-rich cathode are expected to conquer range anxiety for electric vehicles (EVs). However, they suffer from rapid performance fading under inadequate thermal management, particularly during EV applications in summer, due to vigorous parasitic reactions between the Ni-rich materials and the electrolyte and consequent chemical crosstalk at elevated temperature. To address the challenge, a triple-functional additive named triallyl cyanurate (TAC) is proposed in this study, and the mechanism of its function is validated theoretically and experimentally. In detail, TAC builds strong solid electrolyte interphase (SEI) through reduction to protect the anode, forms robust cathode electrolyte interphase (CEI) via oxidation decomposition due to preferable adsorption to restrain the parasitic reactions between the cathode and the electrolyte, and inhibits LiPF₆ hydrolysis to remove HF to lower the corrosivity of the electrolyte. Encouragingly, the TAC-containing electrolyte significantly extends the cycle life of Ah-level pouch cells with various Ni-rich cathodes by 2.5 times at room temperature and 45 °C, as well as extending the high-temperature storage capability by up to 2.8 times. The successful exploration of functional TAC as electrolyte additive presents a promising multi-in-one strategy for additive design, paving a new avenue to boost the application of Ni-rich cathode in LIBs.