Exploring Vacuum-Assisted Thin Films toward Supercapacitor Applications: Present Status and Future Prospects

Abstract

Demand for high-performance energy storage devices is growing tremendously. Supercapacitors possess an excellent candidature to fulfill the energy storage requisites such as high energy density when compared to conventional capacitors, high power density, and cycling stability as compared to batteries, though not only for large-scale devices for higher energy/power density applications but also for macro- to microdevices for miniaturized electrical components. With the aid of various routes, many materials have been explored with well-tuned properties with controlled surface architecture through various preparative parameters to find those best suited for supercapacitive electrodes. Growth of a thin film can be accomplished through chemical or physical (vacuum-assisted) routes. Vacuum-assisted (physical) growth yields high purity, precise dimensions with a line-of-sight deposition, along with high adhesion between the film and the substrates, and hence, these techniques are necessary to manufacture many macro- to microscale supercapacitor devices. Still, much effort has not been put forth to explore vacuum-assisted techniques to fabricate supercapacitive electrodes and energy storage applications. The present review explores the first comprehensive report on the growth of widespread materials through vacuum-assisted physical deposition techniques inclusive of thermal evaporation, e-beam evaporation, sputtering, and laser beam ablation toward supercapacitive energy storage applications on one platform. The theoretical background of nucleation and growth through physical deposition, optimization of process parameters, and characterization to supercapacitor applications from macro- to microscale devices has been well explored to a provide critical analysis with literature-reviewed materials. The review ends with future challenges to bring out upcoming prospects to further enhance supercapacitive performance, as much work and materials need to be explored through these routes.

Li Salt Assisted Highly Flexible Carbonaceous Ni3N@polyimide Electrode for an Efficient Asymmetric Supercapacitor

“…The binder or catalyst used in a chemical route can hinder the properties of the active electrode material. This issue can be addressed by using magnetron sputtering as the fabrication technique because, apart from being a catalyst-free process, one can get a high deposition rate, better adhesion, and desired stoichiometry. − Sputtering provides good control of the electrode thickness and better adhesion of the electrode on the current collector (polyimide tape), which ultimately helps in achieving better capacitive performance with a long life span for charging–discharging . Thus, the thin films fabricated using the sputtering technique can be used in a wide range of applications, such as in catalysis, electrochemistry, magnetism, and electronics …”