Linear and non-linear pseudocapacitances with or without diffusion control

Pseudocapacitance is an important reversible charge storage mechanism in many electrode materials. Although the concept was first proposed in early 1960s, it has been more widely studied following the observation of rectangular cyclic voltammograms (CVs) when testing some transition metal oxides and electronically conducting polymers, and the association with supercapacitor. However, interpretation of pseudocapacitance is inconsistent in the literature. Although all agree that materials are pseudocapacitive if they undergo Faradaic reactions and exhibit rectangular CVs, some have regarded any surface confined Faradaic reactions which may present non-rectangular or even peak-shaped CVs to be pseudocapacitive. In the case of rectangular CVs, the amount of charge stored in the electrode is a linear function of the electrode potential, whilst for non-rectangular or peak-shaped CVs, the relationship is non-linear. It is shown in this article that only linear pseudocapacitance is of relevance to supercapacitor, but non-linear pseudocapacitance may find applications in rechargeable battery and supercapattery. Further, it is clarified that the equation i ​= ​k₁v ​+ ​k₂v^1/2 is useful in analysis of electrode kinetics in terms of surface confinement and diffusion control. However, this kinetic equation is blind to the thermodynamically determined charge storage mechanisms as shown by experimental evidence, and should not be used to differentiate non-capacitive Faradaic processes from pseudocapacitance, either linear or non-linear.     

室温电化学方法制备SrMoO4薄膜

采用恒电流技术于室温条件下直接在金属钼片上制备白钨矿结构的SrMoO4 薄膜 ,控制电化学反应的工艺条件为电流密度为 1mA cm2 、电解液的pH值为 13、电化学处理时间为 1h ,SEM和XRD分析结果表明制备的SrMoO4 薄膜为表面均匀致密且平均粒径为 2 μm的四方晶系单相薄膜 .     

锌镍合金薄层的动电位和恒电流阳极溶出行为

采用动电位法和恒电流法研究了从含有络合剂和有机添加剂的碱性镀液中沉积出的锌镍合金薄层的阳极溶出行为。结果表明，控电位或控电流沉积的Ｚｎ－Ｎｉ合金薄层的动电位阳极溶出峰电位和恒电流阳极溶出曲线的平阶电位可用于表征合金镀层的化学组成和相结构。讨论了碱性镀液体系和酸性体系获得的合金沉积层溶出行为之间的差异。