New Insight into the Role of Mn Doping on the Bulk Structure Stability and Interfacial Stability of Ni‐Rich Layered Oxide

Abstract Nickel‐rich layered oxides have developed into appealing cathode materials for lithium‐ion batteries in recent years for the sake of high energy density and low cost, but they suffer from severe capacity deterioration during long‐term cycling. Herein, Mn‐doped nickel‐rich Li(Ni_0.88Co_0.09Al_0.03)_1‐δMn_δO₂ (δ=0, 0.01, 0.02) cathode materials with a nanoscale Ni_xMn_1−xO‐type pillar layer are synthesized using a facile high‐shear dry mixing and high‐temperature calcination process in this study. The as‐fabricated M0.01−NCA electrode with a Ni_xMn_1−xO‐type layer about 20 nm exhibits excellent cycle performance compared with the pristine in coin‐cells and in pouch cells (the long‐term cycle number is four times that of the pristine). Detailed investigation of the fading mechanism is performed by HRTEM, ex‐situ XRD, XPS et al. The enhanced performance is directly related to the synergetic effects of bulk inactive Mn⁴⁺ doping and the increased nanoscale Ni_xMn_1−xO‐type pillar layer. The Mn dopants stabilize the lattice structure thus decreasing the microcracks, and the pillar layer protects the cathode from parasitic reactions with electrolytes during long‐term cycling. This work gives a new insight into the role of Mn doping on the enhanced structure of nickel‐rich layered oxides.