Investigating the induced effects of physical parameters applied during the electrode preparation, washing, and drying stages on the crystalline aspect and supercapactive performance of nickel-cobalt-aluminium-layered double hydroxides

Abstract

Supercapacitors are promising energy storage devices which fill the gap between conventional capacitors and batteries. They possess several advantages compared to the latter such as safe operation, superior capacitance than conventional capacitors and high-power density compared to batteries. Adding to this, they can be fully charged in the order of seconds and their lifespan is almost unlimited. Finally, they operate under high potential windows and relatively high temperatures. However, they exhibit low energy density compared to batteries. The performance of supercapacitors is intimately linked with the type of electrode active material used. Nanostructured materials have greatly contributed to the improvement of supercapacitors’ performance. Compared to various reported nanostructured materials, layered double hydroxides (LDH) are seen as promising electrode active materials for supercapacitors application due to several advantages that they possess and the synergistic impacts of two or more metal cations that are involved during their preparation which boosts their supercapacitive performance. LDH materials undergo several stages during their synthesis. It is known that the synthesis process involves various stages and during each stage different physical parameters are applied. The literature proves that by varying those physical parameters, the properties of the final product can be altered. Consequently, many strategies were developed whereby various physical parameters were varied and their effects on different properties were reported. However, the physical parameters applied during synthesis stages such as the LDH electrode preparation, washing and drying of LDH precipitates are still not receiving any research interest and the studies dedicated to investigating their impacts on the produced LDH structural aspect and supercapacitive properties of LDH materials are still scarce whereas understanding their impacts could allow improving the supercapacitive optimization rate already recorded. The reason why, this thesis has investigated the induced effects of physical parameters applied during the electrode preparation, washing and drying stages on the crystalline aspect and supercapacitive performance of NiCoAl-LDH products. Based on the collected results and discussions, it was found that these physical parameters have altered the crystalline structure of NiCoAl-LDH and affected accordingly their electrochemical performance.