Investigate the theoretical principles of electrochemical engineering and its applications in energy conversion and storage devices such as fuel cells, batteries, and electrochemical capacitors. Discuss the fundamental electrochemical reactions governing charge transfer, mass transport, and electrode kinetics at the interfaces of electrodes and electrolytes. How do factors such as electrode materials, electrolyte composition, and operating conditions influence the efficiency, capacity, and lifespan of electrochemical devices? Evaluate the engineering strategies for enhancing the performance and durability of electrochemical systems for sustainable energy applications.