Development of High-voltage Supercapacitor for Future Decarbonized Energy Storage Solutions

Abstract

Nowadays, the global energy demand is increasing so rapidly that there is an urgent need of advanced technologies to satisfy the future energy requirements. Conversely, the transition to the low-carbon emission energy is also the future target for the whole world [1]. In this context, electrochemical energy storages (EESs) including batteries and supercapacitors (SCs) play a significant role for the realization of a sustainable decarbonized energy sector, which is expected to reach approximately 1,160 GWh by 2030 [1,2]. However, limited lithium resources, high reactivity and safety issues have imposed lot of constraints for current LIBs market [3]. In such a scenario, owing to their several advantages SCs have the potential to become a driving force for future decarbonized EESs beyond LIBs, where sustainability, cost, safety, recyclability, manufacturability etc. need to be considered [4,5]. In this work, high-voltage (> 2.5 V) symmetric supercapacitor devices have been developed using two polymers (such as Polypropylene Carbonate (PPC), Poly(Vinylidene fluoride-co-Hexafluoropropylene) (PVDF-HFP) etc.) as matrices to embed 1-Ethyl-3-Methylimidazolium bis(trifluoromethylsulfonyl)imide [EMIM][TFSI] ionic liquid electrolyte. Electrochemical performance of these devices has been investigated in form of both coin cell and pouch cell assembles by means of cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), electrochemical impedance spectroscopy (EIS) and cyclic charge discharge (CCD) measurements. The polymer gel electrolyte (PGE) produced with a ratio of [EMIM][TFSI]: PVDF-HFS=1 plus 30 wt.% PC shows better device performance compared to this produced only with the PPC in a cell that is coupled with the commercially available activated carbon (AC) electrodes. This SC delivers a total capacitance of 4.08 Farad @ 0.05 Amp., maximum specific energy density of 10.2 Wh/kg and power density of 562.5 W/kg. It also exhibits negligible capacitance loss with Coulombic efficiency of 98% over 10,000 cycles, which is confirmed by EIS studies before and after CCD measurement. The special aims of this study are to define the performance influences of different PGEs, the processing steps for infiltration of PGEs with different electrode materials and the PGE based device fabrication techniques to obtain high-voltage SCs which can be employed in different aerospace, household and commercial application. Furthermore, on-going research involves the fabrication of SC cells utilizing the optimized PGEs with our own developed graphene-based electrodes for achievement of higher performance SC components. Reference: 1. Cabana, J. et al. ACS Energy Lett. 2023, 8, 740−747. 2. Ray, A. et al. Molecules 27 (1) 2022, 329. 3. Ray, A. Saruhan, B. Materials 14 (11)2021, 2942. 4. Hasa, I. et al. Batteries & Supercaps 2021, 4, 1036–103 5. Ray, A; Korkut, D; Saruhan, B; Nanomaterials 10 (9)2020, 1768