Ta induced fine tuning of microstructure and interface enabling Ni-rich cathode with unexpected cyclability in pouch-type full cell

Abstract

The nickel-rich cathodes are reckoned to be one of the furthest perspective cathode materials for lithium-ion batteries, yet its commercialization suffers from thermal instability and deteriorative cycling lifespan. Herein, a novel tantalum-modified nickel-rich cathode is designed, which integrates the elongated grain microstructures coupled with ordered Li/Ni anti-site defects and an in-situ formed coating layer. This radial structure can alleviate the internal stresses accumulation and restrict the generation and propagation of microcracks. And the ordered Li/Ni anti-site defects facilitate to inhibit the migration and leaching of transition metal ions. Moreover, the tantalum-containing coating layer contributes to ameliorate side reactions and preclude the electrolyte corrosion of interior particles through grain boundaries. Benefitting from the exceptional architecture, the resulting cathode provides superior rate performance and cycling stability, where it maintains a coin cell capacity of 165.06 mAh g−1 after 200 cycles at 1 C and retains a capacity retention of 92.67% in a 2 Ah pouch-type full cell after 1000 cycles. The significantly reinforced thermal and structural reversibility of the modified cathode are also revealed by time-resolved XRD and in-situ XRD.