Construction of LiMn 2 O 4 microcubes and spheres via the control of the (104) crystal planes of MnCO 3 for high rate Li-ions batteries.

We have studied a synthetic route to control the morphology of MnCO 3 precursors. Taking the (104) crystal planes in the structure of MnCO 3 as the research point, the hydrothermal method was used to synthesize MnCO 3 cubes with highly exposed (104) crystal planes and densely crystallized MnCO 3 spheres by changing the water-ethanol reaction system. The MnCO 3 cubes and spheres were used as self templates to prepare spinel LiMn 2 O 4 by thermal decomposition and topological crystallization. The formation mechanism of MnCO 3 and LiMn 2 O 4 was analyzed using characterization methods such as X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. Electrochemical tests evidenced that the electrochemical performance of the as-made cubic and spherical LiMn 2 O 4 significantly improved compared with that of pristine LiMn 2 O 4 . The results manifested that the LiMn 2 O 4 cubes and spheres have superior discharge capacity, delivering first discharge capacities of 130 and 115.1 mA h g -1 at 0.5C, and 96.4 and 88.3 mA h g -1 even at a high rate of 20C, respectively. After calculating the Li + diffusion coefficients of the samples, the results elicited that the diffusion ability of the Li + in the cubic and spherical LiMn 2 O 4 was significantly improved.