Chinnadurai Deviprasath, Selvaraj Aravindha Raja, Rajendiran Rajmohan, Kumar G Rajendra, Kim Hee-Je, Viswanathan K K, Prabakar Kandasamy
Department of Electrical and Computer Engineering, Pusan National University, San 30, Jangjeong-Dong, Gumjeong-Ku, Busan 46241, South Korea.
Kuwait College of Science and Technology, Doha District, Block 4, Safat 13058, Kuwait.
ACS Omega. 2018 Feb 9;3(2):1718-1725. doi: 10.1021/acsomega.7b01762. eCollection 2018 Feb 28.
The stability and performance of supercapacitor devices are limited by the diffusion-controlled redox process occurring at materials' surfaces. Phosphate-based metal oxides could be effectively used as pseudocapacitors because of their polar nature. However, electrochemical energy storage applications of Mn-Co-based phosphate materials and their related kinetics studies have been rarely reported. In this work, we have reported a morphology-tuned Mn Co (PO)·8HO (MCP) spinel compound synthesized by a one-step hydrothermal method. Detailed physical and chemical insights of the active material coated on the nickel substrate are examined by X-ray diffraction, field-emission scanning electron microscopy, field-emission transmission electron microscopy, and high-resolution X-ray photoelectron spectroscopy analyses. Physiochemical studies reveal that the well-defined redox behavior usually observed in Co/Ni surface-terminated compounds is suppressed by reducing the divalent cation density with an increased Co and Mn surface states. A uniform and dense leaflike morphology observed in the MnCo phosphate compound with an increased surface area enhances the electrochemical energy storage performance. The high polar nature of P-O bonding formed at the surface leads to a higher rate of polarization and a very low relaxation time, resulting in a perfect square-shaped cyclic voltagram and triangular-shaped galvanostatic charge and discharge curve. We have achieved a highly pseudocapacitive MCP, and it can be used as a vital candidate in supercapacitor energy storage applications.
超级电容器器件的稳定性和性能受到材料表面发生的扩散控制氧化还原过程的限制。基于磷酸盐的金属氧化物因其极性性质可有效地用作赝电容器。然而，锰钴基磷酸盐材料的电化学储能应用及其相关动力学研究鲜有报道。在这项工作中，我们报道了一种通过一步水热法合成的形貌调控的MnCo(PO)·8H₂O（MCP）尖晶石化合物。通过X射线衍射、场发射扫描电子显微镜、场发射透射电子显微镜和高分辨率X射线光电子能谱分析，对涂覆在镍基底上的活性材料进行了详细的物理和化学洞察。物理化学研究表明，通过增加钴和锰的表面态来降低二价阳离子密度，抑制了通常在钴/镍表面终止化合物中观察到的明确的氧化还原行为。在具有增加表面积的锰钴磷酸盐化合物中观察到的均匀且致密的叶状形貌增强了电化学储能性能。表面形成的P-O键的高极性导致更高的极化率和非常低的弛豫时间，从而产生完美的方形循环伏安图和三角形恒电流充放电曲线。我们制备出了一种具有高赝电容的MCP，它可作为超级电容器储能应用中的重要候选材料。
