Li[Ni0.9Co0.09W0.01]O2: A New Type of Layered Oxide Cathode with High Cycling Stability

Abstract

Substituting W for Al in the Ni-rich cathode Li[Ni0.885Co0.10Al0.015]O2 (NCA89) produces Li[Ni0.9Co0.09W0.01]O2 (NCW90) with markedly reduced primary particle size. Particle size refinement considerably improves the cathode’s cycling stability such that the NCW90 cathode retains 92% of its initial capacity after 1000 cycles (compared to 63% for NCA89), while the cathode produces a high initial discharge capacity of 231.2 mAh g−1 (at 0.1 C). Thus, the proposed NCW90 can deliver high energy density and a long battery lifetime simultaneously, unlike other Ni-rich layered oxide cathodes. This unprecedented cycling stability is mainly attributed to a series of interparticular microfractures that absorb the anisotropic lattice strain caused by a deleterious phase transition near the charge end, thereby improving the cathode’s resistance to fracture. Microcrack suppression preserves the mechanical integrity of the cathode particles during cycling and protects the particle interior from detrimental electrolyte attack. The proposed NCW90 cathode provides an improved material from which a new series of Ni-rich layered cathode can be developed for next-generation electric vehicles.