Contents lists available at ScienceDirect Journal of Energy Storage journal homepage: www.elsevier.com/locate/est Capacitive and diffusion-controlled mechanism of strontium oxide based symmetric and asymmetric devices Muhammad Zahir Iqbal a, ⁎ , Syed Shabhi Haider a,1 , Saman Siddique a,1 , Muhamamd Ramzan Abdul Karim b , Sana Zakar a , Muhammad Tayyab c , Mian Muhammad Faisal a , Muhammad Sulman a , Abbas Khan a , Mehdi Baghayeri e , Muhammad Arshad Kamran d , Thamer Alherbi d , Muhammad Javaid Iqbal f , Tassadaq Hussain g a Nanotechnology Research Laboratory, Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa, Pakistan b Faculty of Materials and Chemical Engineering, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa, Pakistan c Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa, Pakistan d Department of Physics, College of Science, Majmaah University, Al-Majmaah, 11952, Saudi Arabia e Department of Chemistry, Faculty of Science, Hakim Sabzevari University, PO. Box 397, Sabzevar, Iran f Centre of Excellence in Solid State Physics, University of Punjab, Quaid-e-Azam Campus Lahore, 54590, Pakistan g Department of Electrical Engineering, Riphah International University, Islamabad, Pakistan ARTICLE INFO Keywords: Symmetric device Asymmetric device Strontium oxide Supercapattery Battery ABSTRACT A systematic approach has been employed to statistically analyze the Faradaic and non-Faradaic mechanism on electrodes. Two strategies have been adopted for device design, i.e. symmetric and asymmetric, by using the metal oxide synthesized via sonochemical method and activated carbon electrode. Structural and electro- chemical characterization have been performed to investigate the morphological and electrochemical properties of electrode material. Both devices are electrochemically examined by using cyclic voltammetry (CV) and Galvanostatic charge discharge (GCD) measurements to evaluate the electrochemical performance. CV curves are further explored to study the capacitive and diffusive contribution in both devices. The diffusive-controlled contribution at low scan rate in asymmetric device is about 65% which is suitable for supercapattery applica- tions while the symmetric device shows 91% diffusive contribution presenting better performance for battery applications. The strategy unveils the high capacitive and diffusive contribution in asymmetric and symmetric devices, respectively. Results reveal that same material can be exploited for supercapattery and battery appli- cations by implementing different device architectures. 1. Introduction Wide scale production and development of industries demands an excessive supply of energy [1–3]. The inescapable dearth of natural fossil fuel lead researchers to explore sustainable and renewable energy resources. To endure the continuous flow of energy, efficient energy conversion and storage devices are highly desired [4–8]. Owing to high energy density, power density, cyclic life and electrochemical stability, supercapacitors and batteries are widely employed as effective energy storage devices [9,10]. Supercapacitors categorized as electric double layer capacitors (EDLCs) and pseudocapacitors are promising con- tenders for energy storage due to high power density and can be utilized in automobiles, electronic devices such as light emitting diodes (LEDs), smartphones, cranes and elevators [11]. On the other hand, recharge- able batteries, further subdivided into (lithium, sodium, potassium) ion batteries, exhibits high energy density and can be practically applicable in automobiles and power grids [12–16]. Due to remarkable power density and long cyclic life, supercapacitors are mostly preferred energy storage device. Supercapacitors are distinguished as EDLCs and pseu- docapacitors based on charge transfer mechanism. EDLCs comprises of charge transfer between electrode/electrolyte interface through phy- sical adsorption/desorption whereas Faradaic reactions are more pro- minent in pseudocapacitors and batteries [17,18]. Excessively utilized material for EDLCs consist of carbon enriched material such as activated carbons, commonly extracted from biomass i.e. biochar, tea leaves, fruit peels and egg shell etc. [19–22]. Activated https://doi.org/10.1016/j.est.2019.101056 Received 28 September 2019; Received in revised form 31 October 2019; Accepted 31 October 2019 ⁎ Corresponding author. E-mail address: zahir.upc@gmail.com (M.Z. Iqbal). 1 These authors contribute equally to this work. Journal of Energy Storage 27 (2020) 101056 2352-152X/ © 2019 Elsevier Ltd. All rights reserved. T