Tunable Crystal Orientation and Particle Size Enable Stable Co‐Free LNMO Cathode

ABSTRACT The high‐voltage spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) stands as a promising cathode material for lithium‐ion batteries. However, the critical role of sol pH in modulating the crystal orientation and particle size of LNMO synthesized via sol–gel method remains insufficiently explored. Herein, this study focuses on investigating the influence of pH regulation on the crystal orientation, particle size, and electrochemical performance of LNMO. Through adjusting the pH value of the sol and calcination temperature of the resulting gel, LNMO with a truncated octahedral morphology is successfully tailored, characterized by (111)‐ and (100)‐dominant exposed crystal planes and an appropriate amount of Mn 4+ /Mn 3+ ratio. These features endow LNMO with lower Mn dissolution, less solid cathode‐electrolyte interface (CEI) formation and faster Li + transport kinetics, thereby resulting in superior specific capacity, cycling stability, and rate performance. Notably, the optimized LNMO delivers a high capacity of 123.0 mAh g −1 at 0.5C, a favorable capacity retention of 85.2% over 200 cycles at 1C, and a fast Li + diffusion coefficient on the order of 10 −10 cm 2 s −1 . This work emphasizes the significance of sol pH as a key regulatory parameter for tailoring the microstructural and electrochemical properties of LNMO, offering a facile and effective strategy for performance optimization. image