Bulk-to-surface engineering allows for extremely stable co-free Ni-rich cathodes for rechargeable batteries

Cobalt is a costly strategic resource. The outstanding cost advantage of nickel-rich LiNi1-xMnxO 2 (NM) as a replacement for traditional LiNixCoyMnzO 2 as a subsequent commercial cathode in LIBs systems has piqued the interest of many. Nevertheless, the Li-Ni mixing and poor thermal stability of NM result in undesirable surface reactivity and mechanical degradation, which degrades the electrochemical properties of LIBs. Herein, a bulk-to-surface engineering is proposed to achieve a highly stable interface through the combination of Nb-doped and LiNbO 3 -coated LiNi 0.95 Mn 0.05 O 2 (NM95). Compared to numerous nickel-rich and cobalt-poor materials, the performance of the modified NM material is superior. The results affirmed that the strong Nb–O bond in NM95 created by Nb-doping played an undeniable role in structural stability, and that the LiNbO 3 coating layer can stabilize reaction interface, which presents surprising but encouraging perspectives for the application of Co-free Ni-rich cathodes. The modified Nb-NM95 cathode exhibits excellent long cycle stability with a capacity retention rate of 96.6% after 100 cycles at a current density of 1 C. This bulk -to-surface synergistic modification strategy provides a fresh perspective on the construction of Co-free cathodes.