Synergy of doping and coating induced heterogeneous structure and concentration gradient in Ni-rich cathode for enhanced electrochemical performance

Abstract

Structural instability and inferior storage property are bottlenecks of the Ni-rich cathodes. Herein, a coating and doping co-modified Ni-rich cathode, in which La and Al is homogeneously doped in the inner and an epitaxial layer is distributed in the outer surface region of secondary particle, is constructed. The outer surface layer tightly integrates a La2O3 coating layer, an epitaxial grown LaAl doped atomic structure and a Ni concentration gradient into the bulk phase. The La and Al act as a pillar ion enlarging c axis spacing and a positively charged center, enhancing Li+ transportation and suppressing the phase transition. The outer surface region with La-enriched layer and decreased Ni concentration suppresses the side reactions between organic electrolyte and oxidizing Ni4+ and improves the storage stability in air. During cycling, the modified material exhibits enhanced rate capability and cycling stability with capacity retention of 80.0% after 480 cycles at 10C in the cell potential range of 2.7–4.3 V.