A Mg2+/Al3+ dual-doped LiMn2O4 as high-performance cathode material for high-rate and long-cycle lithium-ion batteries

The spinel LiMn 2 O 4 is considered a promising cathode option material because it provides three-dimensional pathways for Li-ion diffusion. However, LiMn 2 O 4 exhibits insufficient rate capabilities and rapid structural deterioration during prolonged cycling, particularly under conditions of high current or elevated temperatures. Herein, we introduce a Mg 2+ /Al 3+ co-doping strategy to evade these problems. As a result, the co-doping of Mg 2+ and Al 3+ facilitates the development of a polyhedral morphology, enhancing both structural stability and rapid Li-ion diffusion. Furthermore, the incorporation of Mg 2+ and Al 3+ , which have a stable electronic configuration, enhances structural stability through their relatively stronger Mg O and Al O bonds compared to the Mn O bond. Therefore, the LiMg 0.02 Al 0.08 Mn 1.90 O 4 delivers the first discharge capacity of 107.6 mAh‧g −1 at 1 C. Importantly, the LiMg 0.02 Al 0.08 Mn 1.90 O 4 cathode 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 Mg 2+ /Al 3+ co-doping facilitates the kinetic process of Li + migration, leading to a relatively high Li + diffusion coefficient and a low apparent activation energy.