Quasi-solid polymer electrolytes for all-in-one self-charging structural energy storage devices

Abstract

In spite of enormous efforts, the world still lacks low-carbon, low-cost, safe and sustainable energy conversion and storage systems as the mobility and digitalization increases. Conversely, the advancements and dominance of flexible, wearable and portable smart electric/electronic components such as smartwatches, mobile phones, health-monitoring devices rapidly increase and require decentralised, off-grid and long-life power supply [1]. In this scenario, simultaneous energy harvesting and storage has been one of the best solutions to minimize the energy crisis and thus, has been thoroughly explored over the last decades. Supercapacitors (SCs) in the form of pouch cells or micro-supercapacitors (MSCs) have attracted much interest as a promising energy storage device due to their several advantages such as fast charge/discharge capability, long lifetime, lightweight, eco-friendliness, easy coupling to energy harvesters and easy structural integration process. SCs containing quasi-solid polymer electrolytes (QSPEs) have attracted increasing attentions for suitable energy storage and powering electronics due to safety, leakage free, interfacial compatibility, good flexibility, high ionic conductivity (10–4 to 10–3 S cm–1 at RT), nonflammability and large mechanical strength [2]. The EU-funded project GRAPHERGIA investigates and develops materials and systems with the purpose of sustainable energy conversion from the human interaction with the environment to electricity. Thus, the project aims to design a Laser-scribed graphene based solid-state micro-flexible supercapacitor, integrated into fibre reinforced composites, coupled to triboelectric nanogenerators (TENGs), via innovative power management circuits, acting as energy reservoirs to provide on-demand battery-less charging of wearable devices and sensors [3]. A part of the GRAPHERGIA, this work reports the development of a high voltage (>2.5 V) supercapacitor, having 1-Ethyl-3-methylimidazolium-bis(trifluormethylsulfonyl)imid [EMIM] [TFSI] ionic electrolyte (IL) integrated polymer matrix (PPC, PC, PVDF-HFP) electrolyte (QSPE) and high Graphene content interdigital electrodes. The detailed electrochemical performance of this QSPE has been tested. The ultimate aim in the project is to fabricate and couple this QSPEs-integrated flexible MSCs with TENGs for various mobile applications such as all-in-one self-charging power textiles, self-powered sensors of aerospace structures and solar powered small satellite devices.