Hybrid systems combining perovskite solar cells and supercapacitors based on coconuts activated carbon for Energy Conversion-Storage devices

The ECS project proposed and developed compact devices called photo-storage devices combining perovskite solar cells and supercapacitors as a solution for concomitant energy harvesting and storage (Sustainable Energy Fuels, 5, 4784-4806, 2021). This compact device was connected through carbon electrodes which is a straightforward way without lossy wiring as used in conventional approaches. Using the experimental resources and analytical platforms in Bordeaux together with the international team from Sri Lanka and Japan the ECS project in a first step, developed effective methods, using environmentally friendly materials, to obtain carbon materials from coconut shell waste. The article related to the synthetic procedure to obtain the carbonaceous materials and their application as electrodes for supercapacitors, published in RSC Advances (RSC Adv., 11, 2854-2865, 2021), has had a strong impact on the scientific community and has received a high number of citations. According to the life cycle analysis study, the CO₂ emissions were significantly decreased by careful selection of the materials and careful control of the activation process, using steam and water as activated agents (ACS Sustainable Chem. Eng. 10, 46, 15025–15034, 2022). The production process is considered, therefore “green" since, on the one hand, the low emissions produced during the activation are absorbed by the plants and are then reused to produce new coconut, on the other hand, the use of biomass allows to save natural sources of activated carbons, which are usually extracted from fossil fuels. In the second step, bio-sourced activated carbon shows outstanding energy storage properties in non-volatile supercapacitors, works in a wide range of potential, and provides high stability over charging/discharging cycles. Finally, once carbon-based perovskite solar cells were successfully developed, the proof-of-concept of sustainable perovskite photo-supercapacitors using bio-sourced activated carbon materials was constructed (www.theses.fr/s345958, Solar Energy Materials and Solar Cells, 247, 111966, 2022). This work proves the great potential for the integrated system to be used in low-power-electronic applications for wide spread usage.