Electrochemical Fundamentals | Electrochemical Charge Storage

This chapter aims to distinguish batteries and supercapacitors, as well as hybrid electrodes and devices, by their root cause of storing charge. Faradaic and capacitive charge storage mechanisms are analyzed, including how the interplay between mass transfer and electrochemical kinetics affects them. The special case of pseudocapacitive charge storage is elucidated and discussed in terms of different schools of thought from the current literature. Common electrochemical techniques are then analyzed to identify—both qualitatively and quantitively—the different charge storage mechanisms possible in hybrid electrochemical materials and devices. Practical guidelines are given to enable researchers to disentangle charge storage mechanisms and define hybrid electrochemical energy storage systems. Lastly, different hybrid cell chemistries and commercial devices are discussed, including open challenges.