Degradation of Ni-rich cathode materials: A multiple fields coupling with negative feedback process

Abstract

Ni-rich cathode materials have recently received phenomenal attention owing to their high energy density and cost-effective nature. Up to now, Li-ion batteries (LIBs) based on Ni-rich layered cathode have been widely used as power source in electric vehicles (EVs). However, Ni-rich cathode materials suffer from serious capacity fading during electrochemical operation and this phenomenon becomes more obvious with the increase of Ni content. The relatively inferior reliability and durability of Ni-rich cathodes lead to some safety hazards and hinder their industrialization. In this context, a great deal of attentions in materials surface/interface chemistries and structure evolution under multiple physicochemical fields operating conditions has been paid to better understand the degradation mechanisms. This article analyzed the origin of multiple fields during operating condition and systematically reviewed the reported failure pathways under different physicochemical fields, providing a detailed understanding on degradation mechanisms of Ni-rich cathodes. Induced degradation pathways from multiple fields coupling lead to further performance degradation, which in turn intensifies the coupling of physicochemical fields. Such a negative feedback loop is believed to responsible for the fast capacity fading of Ni-rich cathode materials. Finally, some insightful future perspectives are also proposed to help further encourage the industrialization of Ni-rich cathodes.