Improved high‐voltage structural stability and rate capability of LiNi _0.91 Co _0.045 Mn _0.045 O ₂ cathode through structure and grain crystallographic orientations design induced by molybdenum modification

Abstract To mitigate capacity fading and enhance the thermal stability of ultrahigh‐nickel cathode materials under high voltage, this study designs and synthesizes a gradient Mo‐modified LiNi 0.91 Co 0.045 Mn 0.045 O 2 cathode with grain crystallographic orientation via a dry method. In situ X‐ray diffraction characterizations and first‐principles calculations reveal that the structural stability of the Mo‐modified cathode at high voltage is significantly enhanced by stabilizing the oxygen framework. Additionally, the radially distributed grains facilitate lithium‐ion diffusion during charge–discharge cycles. Consequently, after 3 wt% MoO 3 modification (NCM@3Mo), the cathode achieves an ultrahigh energy density of 919 Wh kg −1 at 0.1C, with energy density retention improving from 53% to 80% after 200 cycles. Even at a high current density of 5C, a reversible discharge capacity of 198.1 mAh g −1 is maintained. Moreover, the phase transformation temperature from spinel to rock salt of the delithiated Mo‐modified cathode increases by 50 °C during heating. This work presents a comprehensive and robust strategy for the design and synthesis of layered cathode materials that preserve structural integrity at high voltages, thereby meeting the stringent requirements for ultrahigh energy density and enhanced safety in battery systems.