BEGIN:VCALENDAR VERSION:2.0 PRODID:IEEE vTools.Events//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:Europe/Stockholm BEGIN:DAYLIGHT DTSTART:20250330T030000 TZOFFSETFROM:+0100 TZOFFSETTO:+0200 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3 TZNAME:CEST END:DAYLIGHT BEGIN:STANDARD DTSTART:20251026T020000 TZOFFSETFROM:+0200 TZOFFSETTO:+0100 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZNAME:CET END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20251013T084830Z UID:23F02318-53C4-4DE0-B115-0B54E8A6F489 DTSTART;TZID=Europe/Stockholm:20251010T131500 DTEND;TZID=Europe/Stockholm:20251010T140000 DESCRIPTION:Water energy\, from raindrops\, rivers\, and waves\, is a vast renewable resource. Droplet-based electricity generators (DEGs) are lightw eight\, nearly metal-free\, and offer high power density\, making them pro mising for harvesting this energy. However\, two critical challenges hinde r their practical application: significant performance degradation\, poten tially up to 90%\, in existing small-scale integrated panels\, and low eff iciency\, often less than 2%\, in storing the irregular high-voltage pulse d electricity produced by large-scale arrays. In this walk\, I will introd uce our recent progress in scaling up DEGs. By tailoring the bottom electr odes so that their area is comparable to the spread area of the impinging water droplets\, we double the average output power of individual cells an d fabricate large-scale (30-cell) arrays that achieve approximately 2.5 ti mes higher power than state-of-the-art arrays. Furthermore\, without using any power management chip\, we integrate a large-scale (400-cell) micro-s upercapacitor array to store the irregular high-voltage electricity produc ed by the 30-cell generator array at an efficiency of 21.8%. The integrati on of large-scale electricity generators and micro-supercapacitor arrays f orms a simple\, chipless\, self-charging power system with an output power of 81.2 μW\, which is 27 times higher than current systems based on 30-c ell arrays. This work provides important insights towards practical applic ations of droplet-based electricity generators.\n\nMr. Zheng Li is a PhD c andidate at KTH Royal Institute of Technology\, Sweden. He acquired his ba chelor's degree from Southeast University\, China in 2019\, and master’s degree from KTH in 2022. During his master study\, he developed a highly conductive metal-free ink based on conducting polymer and graphene to enab le the scalable fabrication of high-rate on-paper micro-supercapacitors (M SCs). The research was published in [Advanced Functional Materials 32\, 21 08773 (2022)](https://doi.org/10.1002/adfm.202108773) and highlighted by [ Nature Electronics 4\, 769 (2021)](https://www.nature.com/articles/s41928- 021-00677-8). In his PhD study\, Zheng continues to use the high-rate MSCs to improve the energy storage efficiency of the emerging droplet-based el ectricity generators\, as published in [Nature Communications 16\, 8530 (2 025)](https://doi.org/10.1038/s41467-025-64289-y).\n\nEmail: zheng2@kth.se \n\nRoom: Faculty Lounge\, Bldg: Electrum\, Kistagången 16\, Kista\, Stoc kholms lan\, Sweden\, 16440\, Virtual: https://events.vtools.ieee.org/m/50 5244 LOCATION:Room: Faculty Lounge\, Bldg: Electrum\, Kistagången 16\, Kista\, Stockholms lan\, Sweden\, 16440\, Virtual: https://events.vtools.ieee.org/ m/505244 ORGANIZER:jiantong@kth.se SEQUENCE:92 SUMMARY:EPS Nordic Seminar: Efficiency optimization for large-scale droplet -based electricity generator arrays with integrated microsupercapacitor ar rays URL;VALUE=URI:https://events.vtools.ieee.org/m/505244 X-ALT-DESC:Description: <br /><p style="text-align: left\;"><span lang="EN- GB"><img style="border-style: none\; margin-left: 20px\; margin-right: 20p x\;" src="https://events.vtools.ieee.org/vtools_ui/media/display/908a538b- 6940-491c-bc61-c5f90df7944e" width="400" height="300" align="left">Water e nergy\, from raindrops\, rivers\, and waves\, is a vast renewable resource . Droplet-based electricity generators (DEGs) are lightweight\, nearly met al-free\, and offer high power density\, making them promising for harvest ing this energy. However\, two critical challenges hinder their practical application: significant performance degradation\, potentially up to 90%\, in existing small-scale integrated panels\, and low efficiency\, often le ss than 2%\, in storing the irregular high-voltage pulsed electricity prod uced by large-scale arrays. In this walk\, I will introduce our recent pro gress in scaling up DEGs. By tailoring the bottom electrodes so that their area is comparable to the spread area of the impinging water droplets\, w e double the average output power of individual cells and fabricate large- scale (30-cell) arrays that achieve approximately 2.5 times higher power t han state-of-the-art arrays. Furthermore\, without using any power managem ent chip\, we integrate a large-scale (400-cell) micro-supercapacitor arra y to store the irregular high-voltage electricity produced by the 30-cell generator array at an efficiency of 21.8%. The integration of large-scale electricity generators and micro-supercapacitor arrays forms a simple\, ch ipless\, self-charging power system with an output power of 81.2 &mu\;W\, which is 27 times higher than current systems based on 30-cell arrays. Thi s work provides important insights towards practical applications of dropl et-based electricity generators.</span></p>\n<p style="text-align: left\;" >&nbsp\;</p>\n<p class="MsoNormal"><span lang="EN-US" style="color: rgb(35 \, 111\, 161)\;"><strong>Mr. Zheng Li</strong> is a PhD candidate at KTH R oyal Institute of Technology\, Sweden. He acquired his bachelor's degree f rom Southeast University\, China in 2019\, and master&rsquo\;s degree from KTH in 2022. During his master study\, he developed a highly conductive m etal-free ink based on conducting polymer and graphene to enable the scala ble fabrication of high-rate on-paper micro-supercapacitors (MSCs). The re search was published in <span style="color: rgb(186\, 55\, 42)\;"><a style ="color: rgb(186\, 55\, 42)\;" href="https://doi.org/10.1002/adfm.20210877 3">[Advanced Functional Materials 32\, 2108773 (2022)]</a></span> and high lighted by <span style="color: rgb(186\, 55\, 42)\;"><a style="color: rgb( 186\, 55\, 42)\;" href="https://www.nature.com/articles/s41928-021-00677-8 ">[Nature Electronics 4\, 769 (2021)]</a>.</span> In his PhD study\, Zheng continues to use the high-rate MSCs to improve the energy storage efficie ncy of the emerging droplet-based electricity generators\, as published in <span style="color: rgb(186\, 55\, 42)\;"><a style="color: rgb(186\, 55\, 42)\;" href="https://doi.org/10.1038/s41467-025-64289-y">[Nature Communic ations 16\, 8530 (2025)]</a></span>.</span></p>\n<p style="text-align: lef t\;"><span lang="EN-GB" style="color: rgb(35\, 111\, 161)\; background-col or: rgb(236\, 240\, 241)\;"><strong>Email:</strong> <a style="color: rgb(3 5\, 111\, 161)\; background-color: rgb(236\, 240\, 241)\;" href="mailto:zh eng2@kth.se">zheng2@kth.se</a>&nbsp\;</span></p> END:VEVENT END:VCALENDAR