Regulation of morphology evolution and Mn dissolution for ultra-long cycled spinel LiMn2O4 cathode materials by B-doping

Electrochemical properties of spinel LiMn 2 O 4 cathode material have been always suffered from Mn dissolution and Jahn-Teller distortion. Herein, various Ni/B dual-doped LiNi 0.08 B x Mn 1.92- x O 4 ( x  = 0–0.15) with a truncated octahedral morphology are synthesized via a facile solid-state combustion. The effects of Ni/B co-doping on the morphology, crystal structure, Mn dissolution, Li + diffusion coefficient and activation energy are investigated. Due to the relatively high Ni–O and B–O bond energy than that of Mn–O bond, the structure stability of the LiMn 2 O 4 is enhanced, whilst restraining the Jahn-Teller distortion. The LiNi 0.08 Mn 1.92 O 4 shows (111), (110) and (100) facets. In comparison, the B-doping endows the LiNi 0.08 B x Mn 1.92- x O 4 ( x  ≥ 0.02) with (111) and (100) facets. This morphology evolution without (110) facets effectively inhibits the Mn dissolution. Owing to the synergistic merits of Ni/B dual-doping and unique truncated octahedron , the optimized LiNi 0.08 B 0.06 Mn 1.86 O 4 delivers an initial discharge capacity of 113.9 mAh∙g −1 at 1C and maintains a durable cycling life up to 2000 cycles at 5C. Even at 20C, a capacity retention of 86.3% is still obtained after 2000 cycles. Furthermore, a capacity retention of 70.6% can be retained after 500 cycles at 5C and 55 °C. The truncated octahedral LiNi 0.08 B x Mn 1.92- x O 4 with excellent electrochemical performance will be a good candidate for developing long-life lithium-ion batteries.