A Mg2+/Al3+dual-doped LiMn2O4as high-performance cathode material for high-rate and long-cycle lithium-ion batteries

The spinel LiMn2O4is considered a promising cathode option material because it provides three-dimensional pathways for Li-ion diffusion. However, LiMn2O4exhibits insufficient rate capabilities and rapid structural deterioration during prolonged cycling, particularly under conditions of high current or elevated temperatures. Herein, we introduce a Mg2+/Al3+co-doping strategy to evade these problems. As a result, the co-doping of Mg2+and Al3+facilitates the development of a polyhedral morphology, enhancing both structural stability and rapid Li-ion diffusion. Furthermore, the incorporation of Mg2+and Al3+, which have a stable electronic configuration, enhances structural stability through their relatively stronger MgO and AlO bonds compared to the MnO bond. Therefore, the LiMg0.02Al0.08Mn1.90O4delivers the first discharge capacity of 107.6 mAh‧g−1at 1 C. Importantly, the LiMg0.02Al0.08Mn1.90O4cathode achieves long cycling lifespans exceeding 1000 cycles at high current rates of 20 C. A capacity retention of 70.0 % is retained at 20 C after 1000 cycles, as well as a high-temperature capacity retention of 47.4 % after 500 cycles at 5 C and 55 °C. Moreover, the Mg2+/Al3+co-doping facilitates the kinetic process of Li+migration, leading to a relatively high Li+diffusion coefficient and a low apparent activation energy.