Suitability of Ethyl Cellulose As a Binder in Positive Electrode of Aqueous Battery

Abstract

Novel materials for energy storage devices need to be affordable, durable, safe and environmentally friendly. PVDF, which is the most popular polymer used as a binder in battery cathode electrodes, requires the use of and toxic solvents for processing, such as N-methyl-pyrrolidone (NMP).1 Ethyl cellulose is a biodegradable and water-insoluble polymer. Ethyl cellulose based slurry can be prepared using ethanol as solvent, which makes the process cheaper and more sustainable. Replacing PVDF with more environmentally friendly binder like ethyl cellulose in positive electrode of aqueous battery systems would be beneficial in many ways. It would shorten the assembly procedure due to high speed of solvent evaporation, there are no strict requirements for humidity control and the recycling procedure is easier as there are no fluorinated compounds.2 Therefore, this replacement would enable to produce safer and cheaper energy storage devices.In this work electrodes with different composition have been described using galvanostatic charging-discharging and cyclic voltammetry. LiMn2O4 (LMO) has been used as active material for cathode, carbon black Super P as conductive additive and PDVF or ethyl cellulose as a binder. The electrodes were prepared using different mass ratios of conductive additive and binder to evaluate the performance of this sustainable polymer. Using ethyl cellulose as a binder, discharge capacity 100 mAhg− 1 was achieved at 0.2C rate for LMO cathode which is comparable to the results obtained with PVDF as a binder. 500 cycles at the rate of 1C showed somewhat better capacity retention for electrodes prepared using PVDF. However, the results show that ethyl cellulose is a promising option to replace PVDF as cathode binder in aqueous systems. This binder promising option in the application of aqueous redox flow battery with solid boosters, where large amount of solid charge storage material is used in thanks to increase the capacity of the system.The research was supported by the Estonian Research Council grant PUTJD956 and Magnus Ehrnrooth Foundation.