Abstract
Although typical electrochemical double-layer capacitors (EDLCs) operate with aqueous or lithium-free organic electrolytes optimized for activated carbon electrodes, there is interest in EDLCs with lithium-ion electrolyte for applications of lithium ion capacitors and hybridized battery-supercapacitor devices. We present an experimental study of symmetric EDLCs with electrolyte 1 M LiPF6 in EC:EMC 50:50 v/v and electrode coatings with 5 wt% SBR or PEDOT:PSS binder at 5 or 10 wt% concentration, where for the PEDOT:PSS containing electrodes pseudocapacitance effects were investigated in the lithium-ion electrolyte. Two different electrode coating fabrication methods were explored, doctor blade coating and spraying. It was found that EDLCs with electrodes with either binder had a stability window of 0–2 V in the lithium-ion electrolyte. EDLCs with electrodes with 10 wt% PEDOT:PSS binder yielded cyclic voltammograms with pseudocapacitance features indicating surface redox pseudocapacitance in the doctor blade coated electrodes, and intercalation and redox phenomena for the sprayed electrodes. The highest energy density in discharge was exhibited by the EDLC with doctor blade-coated electrodes and 10 wt% PEDOT:PSS binder, which combined good capacitive features with surface redox pseudocapacitance. In general, EDLCs with sprayed electrodes reached higher power density than doctor blade coated electrodes.Graphic abstract
Highlights
There has been increasing interest in supercapacitors with lithium-ion electrolyte targeting applications of lithium-ion capacitors [1] and hybrid battery-supercapacitors [2]
The present study explored activated carbon (AC) electrode coatings for Electrochemical double-layer capacitors (EDLCs) with lithium-ion electrolyte, where two different aqueous binders were investigated, SBR and PEDOT:PSS, at 5 and 10 wt% binder concentration, and two different coating fabrication techniques: doctor blade and spray coating
The first part of the electrochemical testing focused on establishing the potential window of symmetric EDLCs in electrolyte 1 M L iPF6 in EC:EMC 50:50 v/v
Summary
There has been increasing interest in supercapacitors with lithium-ion electrolyte targeting applications of lithium-ion capacitors [1] and hybrid battery-supercapacitors [2]. Spraying can only attain thin coatings, up to 70 μm [37], due to redissolving of binder in consecutive spray passes, which yields low areal density coatings Aqueous binders such as SBR and PEDOT:PSS are preferred as they provide “green” processing for electrode fabrication via either the doctor blade or the spraying technique. We present experimental investigations of symmetric EDLCs with peat bog-derived AC coating electrodes and lithium-ion electrolyte 1 M L iPF6 in EC:EMC 50:50 v/v, where the pseudocapacitance effect of PEDOT:PSS is explored in the lithium-ion electrolyte, using PEDOT:PSS as a binder at two alternative concentrations of 5 wt% and 10 wt%, and compared to SBR binder at 5 wt%. An additional factor in these investigations is the processing technique for coating fabrication, where two alternative methods are investigated: doctor blade coating and spraying
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