A natural rubber based electrolyte to be used in EDLCs with Sri Lankan graphite N.A.A.K. Sanjaya, K.P. Vidanapathirana, K.S. Perera ⇑ Polymer Electronics Research Group, Department of Electronics, Wayamba University of Sri Lanka, Kuliyapitiya, Sri Lanka article info Article history: Received 9 March 2019 Received in revised form 30 April 2019 Accepted 6 May 2019 Available online xxxx Keywords: Natural rubber Natural graphite Super capacitors Solvent casting method Electrochemical double layer capacitors abstract Super capacitors have emerged as a new link to bridge the gap between batteries and conventional capac- itors. In the present study, an electrochemical double layer capacitor (EDLC) was fabricated and its per- formance was evaluated. The novelty of the investigation is use of Sri Lankan natural rubber (NR) and natural graphite (NG) for the electrolyte and electrodes respectively. Cyclic voltammetry test, electro- chemical impedance spectroscopy and galvanostatic charge discharge test were the characterization techniques used in the study. Single electrode specific capacity depends on the potential window of cycling and the scan rate. Capacitive properties become dominant at low frequency regions. Ó 2019 Elsevier Ltd. Peer-review under responsibility of the scientific committee of the Advanced Materials for Clean Energy and Health Applications (AMCEHA). 1. Introduction In the present world, there is an enormous demand for energy due to significant increase of various appliances [1]. It has become a great challenge to seek solutions to fulfill that thirst efficiently and effectively. Upon the universal concerns over clean and low cost concepts, major research focus has been aimed on renewable energy sources. This has automatically highlighted the importance of energy storage devices since renewable energy undergoes fluc- tuations and also have issues related to continuity [2,3]. Since time immemorial, batteries and conventional capacitors have been used as energy storage devices despite some of their drawbacks. The present demand is so huge that they are unable to meet the requirement. Super capacitors have emerged as a new class of energy storage devices which are known to have the capability to bridge the gap between the batteries and capacitors [4]. Electro- chemical double layer capacitors (EDLCs) are a type of super capac- itors that use carbon based electrodes. So far, a substantial amount of research work has been done on EDLCs with liquid electrolytes [5,6]. Due to the demerits of liquid electrolytes such as leaking of corrosive solvents, emitting of harmful gases, having dendrite growth, building up of internal pressure and limited design flexi- bilities, attention has been diverted towards exploring of alterna- tive electrolytes [7]. Solid polymer electrolytes (SPEs) have been recognized as a viable substitute and as a result, a large number of SPEs have been investigated with many modifications over the last several years. In all those systems, commercial polymers have been used which are expensive and in certain cases, hazardous. As a favourable solution for this, attempts are now being made towards bio based polymers among which natural rubber (NR) has received a considerable interest [8]. Several groups have reported about fabrication of electrolytes using modified rubber as it is inherently a non conductor. As modification methodologies, grafting a host polymer and epoxidization are the two common approaches [8,9]. Upto now, all those have utilized NR received from countries like India and Malaysia. In Sri Lanka, NR is one of the major export crops. But, it has not been given a value in the field of energy. The main objective of this study is to investigate the candidacy of Sri Lankan NR to serve in a polymer electrolyte of an EDLC. Novelty of the present investigation lies with the fab- rication and analysis of an EDLC with a Sri Lankan NR based elec- trolyte and Sri Lankan graphite based electrodes. In other words, an EDLC will be fabricated using Sri Lankan raw materials which might allow cost to reduce considerably. 2. Methods NR based electrolytes were prepared using the solvent casting technique. Required amount of NR sample was weighed using a chemical balance and minced into tiny pieces. Then, tetrrahydrofu- ran (Aldrich) was added and left overnight. Stirring was done using https://doi.org/10.1016/j.matpr.2019.05.383 2214-7853/Ó 2019 Elsevier Ltd. Peer-review under responsibility of the scientific committee of the Advanced Materials for Clean Energy and Health Applications (AMCEHA). ⇑ Corresponding author. E-mail address: kumudu@wyb.ac.lk (K.S. Perera). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: N. A. A. K. Sanjaya, K. P. Vidanapathirana and K. S. Perera, A natural rubber based electrolyte to be used in EDLCs with Sri Lankan graphite, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2019.05.383