Introduction

As liquid media at a temperature less than 100 °C that possess some level of ionic conductivity, it is immediately of interest to consider the use of ionic liquids (ILs) as electrolytes to carry out electrochemical processes. This has of course the origins of the modern era of interest in ionic liquids via the work of Wilkes and coworkers in the 1990s [1]. Applications in electrowinning and electrodeposition have developed including processes for a range of metals from copper and zinc to lithium and aluminium [2]. Some metals such as titanium remain, however, stubbornly difficult to electrodeposit [3]. A range of applications in electrochemical devices, including batteries, fuel cells, and solar cells have also emerged and are being thoroughly discussed in Volume 2 (Electrochemistry in ionic liquids. Applications). In parallel to this, there has emerged the need to understand more in detail some important fundamental concepts of electrochemistry as well as the interest on fundamental electrochemical process taking place in an ionic liquid medium and in identifying the ways in which the processes differ, or not, from conventional solvent systems as a result of the highly charged medium [4–6]. Thereby, in this book, special emphasis is placed on showing which aspects of electrochemistry in ionic liquids are different from electrochemistry in conventional solutions. Furthermore, new electrochemical concepts and theories are presented. The book commences with a deep and comprehensive discussion on electrode/electrolyte interface reactions, interface structure, and its critical properties for all electrochemical applications. Chapter 2 discusses these fundamental concepts along with some in situ techniques, such as electrochemical impedance and Fourier transform infrared spectroscopy, cyclic voltammetry, and electrochemical quartz crystal microbalance, suitable for the characterization of electrode/IL interfaces.