MnO2 ultrathin films deposited by means of magnetron sputtering: Relationships between process conditions, structural properties and performance in transparent supercapacitors

• Published in: Superlattices and microstructures 2016-12, Vol.100, p.1213-1220
• Main Authors: Borysiewicz, Michał A., Wzorek, Marek, Myśliwiec, Marcin, Kaczmarski, Jakub, Ekielski, Marek
• Format: Article
• Language: English
• Subjects: Magnetron sputtering; MnO2; Sputtering; Supercapacitor; Transparent electronics; Ultracapacitor; Wearable electronics; ZnO
• ISSN: 0749-6036; 1096-3677
• DOI: 10.1016/j.spmi.2016.11.002

This study focuses on the relationships between the process parameters during magnetron sputter deposition of MnO2 and the resulting film properties. Three MnO2 phases were identified - γ, β and λ and the dependence of MnO2 phase presence on the oxygen content in the sputtering atmosphere was found. Selected MnO2 phases were subsequently applied as ultrathin coatings on top of nanostructured ZnO electrodes for transparent supercapacitors with LiCl-based gel electrolyte. The films containing λ-MnO2 exhibited both the highest optical transparency of 62% at 550 nm as well as the highest specific capacitance in the supercapacitor structure, equal to 73.1 μF/cm2. Initially lower, the capacitance was elevated by charge-discharge conditioning. [Display omitted] •γ, β and λ-MnO2 films deposited by magnetron sputtering of MnO2 target.•λ-MnO2 synthesized for low oxygen conditions.•MnO2/porous ZnO electrodes prepared for symmetric supercapacitors.•λ-MnO2 electrodes exhibited the highest capacitance and transmission values.