Performance, stability and operation voltage optimization of screen-printed aqueous supercapacitors

Abstract

Harvesting micropower energy from the ambient environment requires an intermediate energy storage, for which printed aqueous supercapacitors are well suited due to their low cost and environmental friendliness. In this work, a systematic study of a large set of devices is used to investigate the effect of process variability and operating voltage on the performance and stability of screen printed aqueous supercapacitors. The current collectors and active layers are printed with graphite and activated carbon inks, respectively, and aqueous NaCl used as the electrolyte. The devices are characterized through galvanostatic discharge measurements for quantitative determination of capacitance and equivalent series resistance (ESR), as well as impedance spectroscopy for a detailed study of the factors contributing to ESR. The capacitances are 200–360 mF and the ESRs 7.9–12.7 Ω, depending on the layer thicknesses. The ESR is found to be dominated by the resistance of the graphite current collectors and is compatible with applications in low-power distributed electronics. The effects of different operating voltages on the capacitance, leakage and aging rate of the supercapacitors are tested, and 1.0 V found to be the optimal choice for using the devices in energy harvesting applications.

Highly flexible and non-toxic natural polymer gel electrolyte for printed supercapacitors for IoT

“…In Table 1, the specific capacitance values, ESR and leakage current levels are presented for thicker and thinner gel layers in stencil-printed supercapacitors. In comparison to previous studies [20,22], the ESR level is slightly elevated, which can be mainly explained by the different drying conditions. In this study, no forced convection was used to dry the hand-printed samples to make the results as comparable to the roll-to-roll printed samples as possible, since no forced convection is available on the pilot line used for the upscaling.…”

“…The gel electrolyte used in this work was chosen based on the characterization of various gel compositions and salt concentrations studied in Railanmaa, 2017 [6]. The 2 mol L −1 gelatin gel used in this study combines good ionic conductivity, comparable to the previously studied 1 mol L −1 NaCl (aq) [20], and the sufficient mechanical strength observed in initial testing. The gel was prepared using gelatin powder from porcine skin (Sigma-Aldrich) and sodium chloride (Sigma-Aldrich) dissolved in deionized water.…”

“…The reference samples were identical in structure to the bending samples, i.e., they contained the gel electrolyte as well. Reference samples were measured an equal number of times at equal intervals without mechanical deformation to provide a baseline for the aging of the devices, since especially capacitance and leakage current are somewhat dependent on the number of measurement cycles experienced by the supercapacitor [20]. Because of this, there is unavoidably some small differences between the before and after values, regardless of the bending.…”

Electrochemical analysis of Co3(PO4)2·4H2O/graphene foam composite for enhanced capacity and long cycle life hybrid asymmetric capacitors

“…6(b). This extended voltage could be due to the synergy of the individual material properties of the cathode and anode materials[38].The galvanostatic charge-discharge curves of the Co3(PO4)2.4H2O/GF//C-FP asymmetric device were further tested under different specific currents as shown inFig. 6(c) in the same cell voltage window.…”

Fiber‐Type Solar Cells, Nanogenerators, Batteries, and Supercapacitors for Wearable Applications

“…Screen printing is a coating technique where ink to be coated is pushed using a squeegee on to the substrate, usually a fabric, through a screen mask with a desired pattern. Utilizing this technique wearable supercapacitors or batteries with high power and energy density can be achieved 177, 178, 179, 180. Techniques other than screen printing like ink‐jet printing181 and dip‐coating182 are also used for large‐scale electrode fabrication.…”