Han Xu,Jun Zong,Fei Ding,Zhi-wei Lu,Wei Li,Xing-jiang Liu
To improve the electrochemical performance of LiMnPO4, a modified polyol reaction has been successfully developed for the preparation of LiMnxFe1−xPO4/C samples (x = 0.2, 0.5, 0.8). The secondary particles of the acquired LiMnxFe1−xPO4/C samples are spherical or annular, and the primary particles are nano-sized (20–80 nm). The LiMn0.8Fe0.2PO4/C has a higher energy density of 637 W h kg−1 compared with LiMn0.2Fe0.8PO4/C (575 W h kg−1) and LiMn0.5Fe0.5PO4/C (584 W h kg−1). The TEM image shows that the primary particles of LiMn0.8Fe0.2PO4/C are uniformly covered by a 3 nm carbon layer, and it can deliver a high discharge capacity of 161 mA h g−1 at 0.05C. At a 0.5C discharge rate, the LiMn0.8Fe0.2PO4/C can maintain 80.4% of its initial capacity after 900 cycles, and it also maintains 90% and 83% of its initial capacity at 45 °C and 55 °C respectively after 100 cycles. The results demonstrate that the modified polyol process is feasible for Fe-doping and carbon-coating to enhance the electrochemical performance of LiMnPO4.
All inorganic halide perovskite nanocrystals (NCs) have wider practical applications owing to their good properties, whereas the photoluminescence quantum yield (PLQY) of the purple emissive CsPbCl3 NCs is too low to apply in multi-color displays. In this study, earth-abundant Fe2+ metal ions were successfully incorporated into the lattice of CsPbCl3 NCs with the partial replacement of the sites of Pb2+ ions. The impacts of Fe2+ ions on the luminescence and magnetic properties of CsPbCl3 NCs were studied using photoluminescence spectroscopy (PL), X-ray diffraction spectroscopy (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), and a vibrating sample magnetometer (VSM). CsPb1−xFexCl3 NCs, with x = 0, 0.1, 0.2, and 0.3, were synthesized at 170 °C. It was found that an appropriate amount of Fe2+ doping not only improved the homogeneity of the size of NCs, but also enhanced the PLQY and average PL lifetimes. An obvious hysteresis behavior was observed for the NCs, and there was a significant change in the saturation magnetization value with the increase in the Fe2+ concentration.
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