Architectural modifications for flexible supercapacitor performance optimization

Keskinen, Jari; Lehtimäki, Suvi; Dastpak, Arman; Tuukkanen, Sampo; Flyktman, Timo; Kraft, Thomas; Railanmaa, Anna; Lupo, Donald

doi:10.1007/s13391-016-6141-y

Cited by 41 publications

(32 citation statements)

References 30 publications

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“…The relatively thick PET film was chosen for its good qualities as printing substrate and its good heat resistance; however, the barrier qualities of the film are not very good. We have previously reported results on the optimization of the substrate so that longer-term operation is also possible8.…”

Section: Resultsmentioning

confidence: 99%

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

Lehtimäki

Railanmaa

Keskinen

et al. 2017

Sci Rep

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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.

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Section: Resultsmentioning

confidence: 99%

“…However, printed supercapacitors have also been demonstrated45678 and have potential advantages in numerous applications. For example, energy storage devices printed on flexible substrates, potentially flexible themselves, are needed in many applications of printed, distributed and ubiquitous electronics such as sensors.…”

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confidence: 99%

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

Lehtimäki

Railanmaa

Keskinen

et al. 2017

Sci Rep

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“…6. Considering the electrical characterization results, the skin-compatible printed supercapacitors perform equally to more robustly packaged similar devices both before and after wear 11,13,26 . Leakage current of the wearable devices is slightly higher due to the relatively poor barrier quality of the TPU, but it still does not compromise the function of the supercapacitor.…”

Section: Resultsmentioning

confidence: 98%

“…Supercapacitors 8 are a good candidate for powering these types of devices, since the active materials can be biocompatible in skin contact. They can be printed onto flexible substrates and easily integrated with other printed components [9][10][11][12][13][14] . Several efforts to produce wearable and stretchable supercapacitors have been reported [15][16][17][18] , but so far the reports concerning the durability of the device when worn on the skin are very limited 19,20 , and the existing reports present very short term trials 21,22 .…”

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Skin-conformable printed supercapacitors and their performance in wear

Railanmaa

Soltani

Lehtimäki

et al. 2020

Sci Rep

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Wearable sensors and electronic systems are of great interest these days, but their viability depends on the availability of compatible energy storage solutions. Such sensors can either be integrated into clothing or attached directly to the skin, each case presenting a different set of requirements for the devices. In this work, we examine the performance of printed supercapacitors while attached to the skin. The devices are manufactured from benign materials, such as water, carbon and sodium chloride, and worn on the forearm or chest for 24 h for durability testing. The supercapacitors exhibit excellent mechanical durability and stay well attached under all test conditions. Electrically, the supercapacitors exhibit reliable capacitive function throughout the test period; other key parameters such as equivalent series resistance and leakage current are affected but to a minimal extent. The movement and deformation of the supercapacitor show good compatibility with the skin, as shown by the Digital Image Correlation full field strain measurements on and around the capacitor. The supercapacitors deform with the skin and do not hinder normal movement or function.

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“…Thorough study on optimization of energy efficient resource allocation in M2M communications with energy harvesting [ 15 ] attempts to minimize the total energy consumption of the network via jointly controlling power and time allocation while taking into account circuit power consumption as well as potential QoS and latency constraints. In addition to the basic silicon or CMOS based circuits, also alternative organic/inorganic or printed electronics based solutions are raising interest [ 16 , 17 , 18 ]. Organic (carbon based) electronics incorporate attractive properties of organic small molecule conductors including their electrical conductivity that can be varied by the concentrations of dopants.…”

Section: Introductionmentioning

confidence: 99%

M2M Communication Assessment in Energy-Harvesting and Wake-Up Radio Assisted Scenarios Using Practical Components

Rinne

Keskinen

Berger

et al. 2018

Sensors

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Techniques for wireless energy harvesting (WEH) are emerging as a fascinating set of solutions to extend the lifetime of energy-constrained wireless networks, and are commonly regarded as a key functional technique for almost perpetual communications. For example, with WEH technology, wireless devices are able to harvest energy from different light sources or Radio Frequency (RF) signals broadcast by ambient or dedicated wireless transmitters to support their operation and communications capabilities. WEH technology will have increasingly wider range of use in upcoming applications such as wireless sensor networks, Machine-to-Machine (M2M) communications, and the Internet of Things. In this paper, the usability and fundamental limits of joint RF and solar cell or photovoltaic harvesting based M2M communication systems are studied and presented. The derived theoretical bounds are in essence based on the Shannon capacity theorem, combined with selected propagation loss models, assumed additional link nonidealities, diversity processing, as well as the given energy harvesting and storage capabilities. Fundamental performance limits and available capacity of the communicating link are derived and analyzed, together with extensive numerical results evaluated in different practical scenarios, including realistic implementation losses and state-of-the-art printed supercapacitor performance figures with voltage doubler-based voltage regulator. In particular, low power sensor type communication applications using passive and semi-passive wake-up radio (WuR) are addressed in the study. The presented analysis principles and results establish clear feasibility regions and performance bounds for wireless energy harvesting based low rate M2M communications in the future IoT networks.

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Architectural modifications for flexible supercapacitor performance optimization

Cited by 41 publications

References 30 publications

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

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

Skin-conformable printed supercapacitors and their performance in wear

M2M Communication Assessment in Energy-Harvesting and Wake-Up Radio Assisted Scenarios Using Practical Components

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