2. Thermal Considerations for Supercapacitors

Energy loss in the form of heat generation is inevitable in supercapacitors because coulombic efficiencies are always less than 100 %. The rate of heat generation depends on structural design, power profiles (e.g., charge/discharge rates), and other factors such as voltage imbalances among individual cells within a module. This heat generation causes a temperature rise within the cells. For instance, voltage imbalances can occur in a series string of supercapacitor modules, resulting in temperature differences among the cells. Reliability issues arise when some cells with higher temperatures fail sooner than others, since high temperature generally causes shorter life for the cells. Thus thermal management of supercapacitor systems is important for practical applications. This chapter provides a general discussion of thermal management in supercapacitors, including different practical applications, thermophysical properties of supercapacitor components, thermal transport mechanisms, thermal characterization techniques, performance metrics, and cooling systems. This chapter paves the way for the following chapters that address thermal influences on supercapacitor components and performance.