Dual-modified engineering suppressed the formation of Li-concentration gradient and oxygen vacancies for single-crystal Ni-rich layered cathodes

Abstract

Ni-rich single-crystal layered cathodes, LiNixCoyMnzO2 (SC-NCM, x ≥ 0.6), have been considered as the most favorable candidates for next-generation high-performance batteries. However, the rapid lithium concentration gradient and increased oxygen vacancies, caused by electrode/electrolyte interface degradation, are the primary reasons leading to the formation of irreversible intergranular cracks and the deterioration of material properties. Herein, the dual-modified LiNi0.6Co0.2Mn0.2O2 (SC-NCM622) nanoparticle with LiTaO3 protective layer containing Ta5+ is synthesized by a facile sol–gel method. The dual-modified strategy could provide rapid lithium-ion channels, effectively relieving stress evolution, polarization, and dynamic degradation of cathode materials during cycling. This strategy hinders the formation of oxygen vacancies on the cathode surface and prevents the development of intragranular cracks. As expected, the 2 wt% LTO@SC-NCM622 exhibits excellent capacity retention of 90.39 % at 1 C after 200 cycles. Even at 10 C, the 2 wt%LTO@SC-NCM622 retains a specific capacity of 88.7 mAh g−1 (82.7 %) after 500 cycles. This work offers guidance for the design of new stable Ni-rich cathodes for next-generation LIBs.