Challenges and Strategies towards Single-Crystalline Ni-Rich Layered Cathodes

摘要

The ever-increasing energy density requirements in electric vehicles (EVs) haveboosted the development of Ni-rich layered oxide cathodes for state-of-the-artlithium-ion batteries. Nevertheless, the commercialization of polycrystallineNi-rich cathodes (PCNCs) is hindered by the severe performance degradationand safety concerns that are tightly related to its particle cracking duringcycling. Single-crystalline Ni-rich cathodes (SCNCs) with eliminated grainboundaries and high mechanical strength have recently attracted extensiveattention owing to their superior structural and cycling stability, which presenthigh crack resistance during electrochemical operation. Various articles havefocused on the trial-and-error synthesis and modifications of SCNCs, as wellas the comparison of performances and mechanisms with PCNCs. However,there has been much less effort in systematic analysis and summary to revealtheir key challenges, controversies, and the corresponding primary causes.In this review, the advantages and debates in structural and electrochemicalproperties of SCNCs over PCNCs are summarized to provide fundamentalunderstanding of SCNCs. Then the current practical issues and challengesare comprehensively discussed from the viewpoints of both academia andindustry, as well as the proposed modification strategies and underlying mechanismsfor SCNCs. The outlook and perspectives are further given to facilitatethe commercial applications of SCNCs in high-performance EVs.