Recyclable liquid metal – Graphene supercapacitor

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-01, Vol.479, p.147894, Article 147894
• Main Authors: Sanati, Afsaneh L., Alhais Lopes, Pedro, Chambel, Alexandre, Silva, André F., Oliveira, Diogo M., Majidi, Carmel, de Almeida, Anibal T., Tavakoli, Mahmoud
• Format: Article
• Language: English
• Subjects: Eutectic gallium indium liquid metal; Recyclable supercapacitor; Reduced graphene oxide; Stretchable energy storage; Wearable electronics
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2023.147894

•The first application of Gallium LM Nanodroplets for energy storage devices.•Graphene Oxide coating prevents LM aggregation within highly alkaline electrolytes.•10x higher energy storage using GO@LM supercapacitor instead of bulk LM.•Low-cost fabrication integrates energy harvesting and storage using rGO@EGaIn.•Flexible current collectors enable device deformation into various configurations. Because of their high electrical conductivity, fluidic deformability, self-healing properties, and the possibility of recycling, Ga-based liquid metal alloys like eutectic gallium indium (EGaIn) have tremendous potential as electrodes for stretchable energy storage devices. However, EGaIn droplets could never be used as electrodes in thin-film supercapacitors (SCs) at the desired micro/nano scale, because they rapidly coalesce into bulk EGaIn when contacting acidic/alkaline electrolytes. Here, we show that coating EGaIn droplets with only 0.08 wt% of reduced graphene oxide (GO) nanosheets tremendously improves their chemical stability. We fabricated binder-free GO-coated EGaIn nanocomposite electrodes that show excellent stability in a strong alkaline electrolyte. We demonstrated a symmetric soft-matter pseudo-SC with areal capacitances of 1200mF/cm2@0.3 mA/cm2 and 220mF/cm2@1mA/cm2, which is > 10 × compared to previous SCs based on bulk EGaIn. This SC retains 98.4 % of the initial capacitance after 4000 electrochemical cycles and exhibits comparable self-discharge rates to state-of-the-art flexible pseudo-SCs. Surprisingly, applying mechanical strain results in improved areal capacitance. We demonstrate rapid, laser-based fabrication of a wirelessly chargeable elastic film with an integrated energy harvesting antenna and energy-storage SC that can be used in wearable biomonitoring patches, and e-textiles. Finally, we demonstrate the recovery of the metals from the disposed of SCs through an electrowinning technique.