The hydrothermal synthesis, crystal structure and electrochemical properties of MnSb2O4†
Abstract
Phase pure polycrystalline MnSb2O4 was synthesised under hydrothermal conditions. Impurities formed outside a narrow range of pH and metal stoichiometric ratios. The structure and its temperature dependence was studied based on multi-temperature conventional single crystal X-ray diffraction (SC-XRD) and high resolution synchrotron powder X-ray diffraction (PXRD). At low temperature (100–300 K) the lattice parameters expanded linearly with thermal expansion coefficients of αa,300 K = 8(1) × 10−6 K−1 and αc,300 K = 7.2(2) × 10−6 K−1. At high temperature an irreversible annealing effect was observed. Modelling the atomic displacement parameters based on the single crystal X-ray diffraction data gives a Debye temperature of 267(3) K for MnSb2O4. When heated in an oxygen-rich atmosphere MnSb2O4 oxidises above 800 K and it decomposes at 975 K under inert conditions. Electrochemical measurements displayed similar behaviour to the isostructural CoSb2O4, with reversible alloying–dealloying of LixSb after the first cycle with a reversible capacity of 337 mAh g−1 at the 2nd cycle, which degraded to c. 100 mAh g−1 after 30 cycles.