Surface Engineering for Advanced Aqueous Supercapacitors: A Review

: Considerable attention has been focused on aqueous supercapacitors (SCs), owing to their large power density and excellent cycling stability, which makes them more suitable for high power applications. However, the lower energy densities (E) of aqueous SCs as compared to batteries have impeded their range of commercial applications. To overcome this challenge, intensive studies have been devoted to the topic, in which surface engineering becomes critical to the high-performance electrode design due to the efficient manipulation of a material surface to boost energy storage while maintaining the integrity of interior of the material. The purpose of this Minireview article is to highlight recent significant breakthroughs realized through surface engineering approaches such as surface functionalization, heterostructure design, and surface charge modulation. Current challenges, emerging trends, and opportunities for advanced SCs are discussed accordingly.