Facile solid-state combustion synthesis of Al–Ni dual-doped LiMn2O4 cathode materials

A series of aluminum and nickel (Al–Ni) co-doped LiAl 0.15 Ni x Mn 1.85− x O 4 composites are prepared through a facile solid-state combustion method. All the as-obtained materials show a spinel structure and analogous spherical morphology with uniform particle distribution. Moreover, the synergistic merits of Al and Ni dual substitutions endow the spinel LiMn 2 O 4 with an elevated Mn average valence state of 3.59 and relatively alleviative Jahn–Teller distortion. Among these samples, the LiAl 0.15 Ni 0.03 Mn 1.82 O 4 (LANMO-0.03) cathode exhibits an optimal electrochemical performance with the discharge capacities of 103.3 mAh g −1 and 102 mAh g −1 at 1 C and 5 C in the first cycle, and the capacity retentions are 72.0% and 68.6% after 1000 cycles, respectively. Even at 1 C and high temperature of 55 °C, an excellent capacity retention remained to be 76.6% after 200 cycles. Furthermore, the LANMO-0.03 has good Li + diffusion capability during charge/discharge, the D Li + value of the LANMO-0.03 (1.65 × 10 –11 cm 2 ∙s −1 ) is higher than that of the LiAl 0.15 Mn 1.85 O 4 (LAMO) (8.12 × 10 –12 cm 2 ∙s −1 ), and the charge transfer resistances of the LAMO and LANMO-0.03 samples are almost the same at 150 Ω before cycling but decrease to 130 Ω and 95 Ω after 1000 cycles at 1 C, respectively. These results demonstrate that the Al–Ni co-doped strategy can enhance the structural stability and provide stable Li + diffusion channel during the long cycles even at elevated temperature. Meanwhile, the facile solid-state combustion approach can also be extended to the preparation of other dual cation-doped electrode materials.