Minakshi Sundaram Manickam, Biswal Avijit, Mitchell David, Jones Rob, Fernandez Carlos
School of Engineering and Information Technology, Murdoch University, Murdoch, WA 6150, Australia.
Electron Microscope Centre, Australian Institute for Innovative Materials, Innovation Campus, University of Wollongong, North Wollongong, NSW 2500, Australia.
Phys Chem Chem Phys. 2016 Feb 14;18(6):4711-20. doi: 10.1039/c5cp07141k.
An attempt has been made to correlate the differences in structural parameters, surface areas, morphology etc. with the electrochemical capacitive behaviour of the EMDs. The nanostructured electrolytic manganese dioxides (EMD) have been synthesized through electrodepositing MnO2 from two different leach liquors and a synthetic analogue thereof. The structural and chemical state was determined using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) respectively. Multiplet structure determination led to estimates of the manganese valence states present in the EMD. The EMDs have been tested in an asymmetric capacitor which we have developed. This used activated carbon as the negative electrode and the various EMDs as the positive electrode. Aqueous 2 M NaOH solution was used as the electrolyte. The capacitor achieved 1.6 V corresponding to a capacitance of ∼50 F g(-1) of the EMDs from leach liquors. The EMD derived from the synthetic solution showed an inferior capacitance of 25 F g(-1). Extended cycling (2000 cycles), showed 100% capacity retention was achieved for one EMD produced from the leach liquor derived from low-grade manganese ore/residue. This outstanding capacitor performance was correlated with the presence of a nanofibrous morphology. These findings open up the possibility of extracting a high performance EMD product from a low cost, low-grade source of manganese.
人们尝试将结构参数、表面积、形态等方面的差异与电解二氧化锰（EMD）的电化学电容行为关联起来。通过从两种不同的浸出液及其合成类似物中电沉积MnO₂，合成了纳米结构的电解二氧化锰（EMD）。分别使用X射线衍射（XRD）和X射线光电子能谱（XPS）确定结构和化学状态。多重结构测定得出了EMD中存在的锰价态估计值。这些EMD在我们开发的非对称电容器中进行了测试。该电容器使用活性炭作为负极，各种EMD作为正极。使用2 M NaOH水溶液作为电解质。该电容器的电压达到1.6 V，对应于浸出液中EMD的电容约为50 F g⁻¹。源自合成溶液的EMD表现出较差的电容，为25 F g⁻¹。长时间循环（2000次循环）表明，由低品位锰矿石/残渣浸出液制得的一种EMD实现了100%的容量保持率。这种出色的电容器性能与纳米纤维形态的存在有关。这些发现为从低成本、低品位的锰源中提取高性能EMD产品开辟了可能性。
