Improving Electrochemical Performance of LiNi 0.5 Mn 1.5 O ₄ Cathode Material by Al/Co Co‐doping

Spinel LiNi 0.5 Mn 1.5 O 4 is a promising high‐voltage cathode material for lithium‐ion batteries, but its application is limited by Mn dissolution and poor high‐temperature stability. Herein, Al‐doped, Co‐doped, and Al/Co codoped LNMO materials were synthesized via a high‐temperature solid‐state method. All samples retain the spinel structure (Fdm), while Al and Co doping reduces Mn 3+ content, induces lattice contraction, and enhances structural stability. The Al/Co codoped LNMO exhibits reduced polarization, enhanced Li + diffusion kinetics, and improved cycling and rate performance. Notably, it retains 96.7% of its initial capacity after 100 cycles at 50°C and 1°C, accompanied by suppressed Mn dissolution. These results demonstrate that Al/Co codoping is an effective strategy to improve the structural and electrochemical stability of LNMO under high‐temperature conditions.