Easy approach to synthesize N/P/K co-doped porous carbon microfibers from cane molasses as a high performance supercapacitor electrode material† Alfin Kurniawan, a L. K. Ong, a Fredi Kurniawan, a C. X. Lin, b Felycia E. Soetaredjo, a X. S. Zhao * c and Suryadi Ismadji * a In this study, we demonstrate a simple and low cost method to synthesize N/P/K co-doped porous carbon microfibers (CMFs) from a sugar-rich byproduct (cane molasses) as the precursor material. A two-step method for the synthesis of N/P/K co-doped porous CMFs involving electrospinning of precursor material followed by simple carbonization at various temperatures (773.15–1173.15 K) was successfully applied. The N/P/K co-doped porous CMFs exhibited high specific surface area (580 m 2 g 1 ) and hierarchical porous structure. The potential application of N/P/K co-doped porous CMFs as supercapacitor electrodes was investigated in a two-electrode configuration employing aqueous K 2 SO 4 solution and ionic liquids/acetonitrile (ILs/ACN) mixtures as the electrolytes. A series of electrochemical measurements include cyclic voltammetry, galvanostatic charge–discharge and cycling durability all confirmed that the CMF-1073.15 supercapacitor exhibited good electrochemical performance with a specific capacitance of 171.8 F g 1 at a current load of 1 A g 1 measured in 1.5 M tetraethylammonium tetrafluoroborate (TEABF 4 )/ACN electrolyte, which can be charged and discharged up to a cell potential of 3.0 V. The specific energy density and power density of 53.7 W h kg 1 and 0.84 kW kg 1 were achieved. Furthermore, the CMF-1073.15 supercapacitor showed excellent cycling performance with capacitance retention of nearly 91% after 2500 charge–discharge cycles, characterizing its electrochemical robustness and stable capacitive performance. 1. Introduction Li-ion batteries and supercapacitors have gained increasing attention over the past decade and are currently considered to be promising energy storage devices for creating sustainable and high efficiency energy systems. These energy storage devices have a key role to play in energy storage and harvesting where high energy or high power delivery are required. The charge storage mechanisms in supercapacitors are based on the two following mechanisms: 1 (1) electrostatic storage at the electrolyte–electrode interface through reversible adsorption of ions on the surface of active electrode material when a potential difference is applied or (2) faradaic electrochemical storage with electron charge-transfer on the electrode originated from reversible redox reactions, intercalation or electrosorption. Given this, supercapacitors can be charged and discharged quickly and their energy storage capability can last for thou- sands to millions of charging–discharging cycles. However, the main shortcoming of supercapacitors is their low energy density particularly when compared to batteries. Additionally, the cost of electrode materials such as graphene, carbon nanotubes (CNTs), carbon aerogels and transition metal oxides to construct high electrocapacitive performance and exible supercapacitors oen exceeds the cost of battery materials. Recent technological challenges and research frontiers in supercapacitors have been directed toward the development of new and less expensive electrode materials to bridge the energy density gap for designing next-generation supercapacitors. Porous carbons are the most common electrode materials used today in supercapacitors; owing to their attracting features include high specic surface area, accommodates surface chemical attributes that can promote the double-layer capaci- tive performance, thermally and chemically stable and tunable porous structure to ease the transport of electrolyte ions for a Department of Chemical Engineering, Widya Mandala Surabaya Catholic University, Kalijudan 37, Surabaya 60114, Indonesia. E-mail: suryadiismadji@yahoo.com; Fax: +62 31 389 1267; Tel: +62 31 389 1264 b Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia c School of Chemical Engineering, The University of Queensland, Brisbane, QLD 4072, Australia. E-mail: george.zhao@uq.edu.au; Fax: +61 7 3365 4199; Tel: +61 7 3346 9997 † Electronic supplementary information (ESI) available. See DOI: 10.1039/c4ra05243a Cite this: RSC Adv. , 2014, 4, 34739 Received 2nd June 2014 Accepted 4th August 2014 DOI: 10.1039/c4ra05243a www.rsc.org/advances This journal is © The Royal Society of Chemistry 2014 RSC Adv. , 2014, 4, 34739–34750 | 34739 RSC Advances PAPER