Building a Self-Adaptive Protective Layer on Ni-Rich Layered Cathodes to Enhance the Cycle Stability of Lithium-Ion Batteries

Layered Ni-rich lithium transition metal oxides are promising battery cathodes due to their high specific capacity, but their poor cycling stability due to intergranular cracks in secondary particles restricts their practical applications. Surface engineering is an effective strategy for improving a cathode's cycling stability, but most reported surface coatings cannot adapt to the dynamic volume changes of cathodes. Herein, a self-adaptive polymer (polyrotaxane-co-poly(acrylic acid)) interfacial layer is built on LiNi0.6Co0.2Mn0.2O2. The polymer layer with a slide-ring structure exhibits high toughness and can withstand the stress caused by particle volume changes, which can prevent the cracking of particles. In addition, the slide-ring polymer acts as a physicochemical barrier that suppresses surface side reactions and alleviates the dissolution of transition metallic ions, which ensures stable cycling performance. Thus, the as-prepared cathode shows significantly improved long-term cycling stability in situations in which cracks may easily occur, especially under high-rate, high-voltage, and high-temperature conditions.

Automated summary

In this study, a self-adaptive polymer interfacial layer with a slide-ring structure was built on layered Ni-rich lithium transition metal oxide cathode to improve its cycling stability. The polymer layer exhibited high toughness and could withstand the stress caused by particle volume changes, thus preventing particle cracking. Additionally, the polymer acted as a physicochemical barrier, suppressing surface side reactions and reducing the dissolution of transition metallic ions, resulting in stable cycling performance. The as-prepared cathode showed significantly improved long-term cycling stability, especially under high-rate, high-voltage, and high-temperature conditions where cracks may easily occur.