3D flower-like MnCO₃ microcrystals: evolution mechanisms of morphology and enhanced electrochemical performances

Graphical abstract: Schematic illustration for the possible formation mechanism of 3D flower-like MnCO₃ microcrystals. Display Omitted -- Highlights: •3D flower-like MnCO₃ microcrystals have been synthesized with the addition of Na₃Cit. •The influences of reaction time and dosage of Na₃Cit on the morphology of MnCO₃ microcrystals were investigated. •A mechanism for the morphology evolution of 3D flower-like MnCO₃ microcrystals were proposed. •The 3D flower-like MnCO₃ microcrystals exhibit the significantly enhanced cycling performance. •This work provide valuable insight into the researches on the formation mechanism for inorganic compounds. -- Abstract: 3D flower-like MnCO₃ microcrystals have been prepared via a facile hydrothermal method with the addition of sodium citrate (Na₃Cit). The microstructures of the prepared microcrystals were characterized through X-ray diffraction (XRD), scanning electron microscope (SEM), thermogravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR) and N₂ adsorption. Moreover, a mechanism for the morphology evolution of 3D flower-like MnCO₃ microcrystals was also discussed in detail. Using the obtained 3D flower-like MnCO₃ microcrystals as anode for lithium ion batteries and a series of tests including charge-discharge test, cycling ability, rate performances, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out. The results show that 3D flower-like MnCO₃ microcrystals can be obtained by varying the reaction time and the dosage of Na₃Cit at the hydrothermal temperature of 180 °C, and the suitable hydrothermal reaction time and the dosage of Na₃Cit for the 3D flower-like MnCO₃ microcrystals are 12 h and 3 mmol, respectively. The electrochemical measurements indicate that 3D flower-like MnCO₃ microcrystals exhibit specific capacity of 384 mAh g⁻¹ at 0.2 C after 200 cycles, showing the significantly enhanced cycling performance than that of the obtained spherical MnCO₃ microcrystals.