Understanding the Ni-rich layered structure materials for high-energy density lithium-ion batteries

The development of electric and hybrid electric vehicles has emerged as one of the most promising strategies for solving the global shortage of fossil energy problem. High-energy and high-power lithium-ion batteries are essential for achieving the large-scale commercialization of electric vehicles. Ni-rich layered-structure oxides appear to be one of the most ideal candidates for electrode materials owing to their high-energy density. However, severe degradation issues associated with chemical and structural instabilities have limited their further applications. This review summarizes recent progress toward the fundamental understanding of ternary layered-structure oxides with a particular focus on the key issues of ion intermixing, chemo-mechanical degradation, and phase evolution on the particle surface. The possible strategies, as well as perspectives for addressing these problems, are also proposed in this review as an effort to provide guidance on the further design of advanced layered-structure oxides.