The rapid capacity decay of spinel LiMn₂O₄ is attributed to the occurrence of Jahn-Teller distortion and Mn dissolution, which restricts commercial application. Herein, a low temperature solid state combustion method was employed to synthesize various LiAl_0.03Co_xMn_1.97-xO₄ (x≤0.08) cathode materials. The results show that Al-Co co-doping reduces the surface energy barrier of truncated octahedral {111}, {100} and {110} crystal faces, increases the heterogeneous nucleation, promotes the development of truncated octahedral crystals, reduces Mn dissolution and widens the Li⁺ diffusion channels. The optimal LiAl_0.03Co_0.03Mn_1.94O₄ cathode material has a single-crystal particle morphology of completely truncated octahedron and its average Mn valence increases from +3.5 to +3.545, thereby effectively inhibiting Jahn-Teller distortion, stabilizing the crystal structure, and improving the high-rate performance and long-cycle life of the material. At 5 and 10 C, it delivers the first discharge capacities of 108.6 and 104.9 mAh/g with the high capacity retentions of 70.4% and 75.5% after 2000 long cycles, respectively. At a higher rate of 20 C, it shows a low-capacity fade of 9.3% after 500 cycles. The LiAl_0.03Co_0.03Mn_1.94O₄ material has a low apparent activation energy (22.84 kJ/mol) and a relatively high Li⁺ diffusion coefficient (5.47×10^-16 cm²/s), indicating that it has a good lithium-ion migration kinetics.