The Li1.02Ni0.05Mn1.93O4 cathode material exhibits a better rate capability than that of the LiNi0.05Mn1.95O4. Moreover, the Li1.02Ni0.05Mn1.93O4 shows the well-developed crystal structure with the (111), (110) and (100) crystal planes. The (111) crystal planes possess the minimum Mn dissolution and the (110) and (100) crystal planes are well consistent with the Li+ diffusion channel. Display omitted Various Li-rich spinel Li1+xNi0.05Mn1.95-xO4 (0 ≤ x ≤ 0.10) cathode materials with a truncated octahedron were synthesized by a solution combustion method. The relationship of crystalline structure, particles morphology and electrochemical properties of the as-prepared samples was investigated via a series of physicochemical characterizations. The Li-Ni co-doping changes the lattice parameters and atomic configuration, whilst resulting in a contraction of unit cell dimension and giving rise to a variation of bond length. In this regard, the shrinkage of octahedral MnO6 provides a robust structure and the expansion of tetrahedral LiO4 facilitates a fast electrochemical process. Additionally, the resulted polyhedral Li1+xNi0.05Mn1.95-xO4 samples present the exposed (110), (100), and (111) crystal planes, which provide the favorable Li+ ions diffusion/transmission channel and alleviate Mn dissolution. Owing to these merits of polyhedral structure and Li-Ni co-doping, the optimized Li1.02Ni0.05Mn1.93O4 exhibits good electrochemical performance with high initial discharge capacity of 119.8, 107.1 and 97.9 mAh·g−1 at 1, 5 and 10 C, respectively. Even at a high current rate of 15 C, an excellent capacity retention of 91.7% is obtained after 1000 cycles, whilst the high temperature performance was also improved.