Synthesis of Well‐Crystallized, High‐Performance LiNi 0.5 Mn 1.5 O 4 Octahedra as Lithium‐Ion‐Battery Electrode Promoted by Metal Manganese Powders

Metal Mn powders instead of conventional Mn salts were used for the first time tried as a Mn source to synthesize high‐performance LiNi 0.5 Mn 1.5 O 4 (M‐LNMO) using a sol–gel method. Mn powders promote the formation of well‐crystallized octahedra with the Fd 3 m spinel structure. M‐LNMO has a lower stress, a slightly smaller lattice constant, which arises from the lower amount of Mn 3+ because of the lower oxygen deficiency, a higher cation ordering, and longer Li−O and shorter Mn (Ni)−O bonds than LiNi 0.5 Mn 1.5 O 4 synthesized from manganese acetate (MA‐LNMO). The well‐crystallized octahedra, the low stress, the low amount of Mn 3+ , and the long Li−O and short Mn (Ni)−O bonds for M‐LNMO result in its excellent performance such as a discharge capacity of 68 mAh g −1 at 50 C and a capacity retention of 90 % after 600 cycles at 10 C. This study raises the possibility to promote the synthesis of high‐performance LiNi 0.5 Mn 1.5 O 4 for mass production by using cheap and simple Mn sources such as Mn powders.