Surface-engineered Nanomaterials for Supercapacitors

Due to their superior power output and longevity, supercapacitors (SCs) have drawn substantial interest for compact electronic devices. Supercapacitors store electrical energy using two different mechanisms: a Faradaic process that involves redox reactions at the electrode (pseudocapacitance) and ion adsorption at the electrode/electrolyte interface (electric double-layer capacitance, or EDLC). Unfortunately, the unavailability of high-performance electrode materials has hindered SCs from being used because of their low energy densities. Surface modification has long been considered a valuable technique to control the surface characteristics of nanoparticles. Surface engineering is accomplished by reducing the size of the particles, managing their morphologies, and developing structured, porous networks to improve the electrochemical capabilities of electrode materials. This chapter explores how variations in size, shape, and pore configuration affect the electrode/electrolyte interface. The electrodes suffer from poor ionic and electronic conductivities. Surface modification suppresses the surface reactions to enhance electrolyte decomposition. Therefore, different surface engineering methods to enhance supercapacitor performance such as surface functionalization, heterostructure around the surface, and surface precharge for higher potential windows are briefly discussed. Finally, the performance of different electrode materials, challenges and future perspectives are discussed for the electrochemical performance of supercapacitor nanomaterials.