This new volume discusses new and well-known electrochemical energy harvesting, conversion, and storage techniques. It provides significant insight into the current progress being made in this field and suggests plausible solutions to the future energy crisis along with approaches to mitigate environmental degradation caused by energy generation, production, and storage. Topics in Electrochemical Energy Conversion and Storage Systems for Future Sustainability: Technological Advancements address photoelectrochemical catalysis by ZnO, hydrogen oxidation reaction for fuel cell application, and miniaturized energy storage devices in the form of micro-supercapacitors. The volume looks at the underlying mechanisms and acquired first-hand information on how to overcome some of the critical bottlenecks to achieve long-term and reliable energy solutions. The detailed synthesis processes that have been tried and tested over time through rigorous attempts of many researchers can help in selecting the most effective and economical ways to achieve maximum output and efficiency, without going through time-consuming and complex steps. The theoretical analyses and computational results corroborate the experimental findings for better and reliable energy solutions.