Supercapacitors: shaping the future energy storage landscape for flexible, implantable and wearable electronic devices

Recent innovations in the fields of nanotechnology have resulted in the development and widespread applications of flexible, implantable and wearable electronic devices (FIWEDs). Almost all of these miniaturised devices are powered by lithium-ion batteries which are bulky in nature and present an immense challenge towards miniaturization, safety, environmental sustainability and extension in lifespan. Therefore, it is of paramount importance to explore new materials and design strategies for taking on the challenging task of designing next generation of energy storage devices. Supercapacitors (SCs) also known as ultracapacitors have gained enhanced attention from scientific communities due to their superior and promising features such as cost-effectiveness, non-toxic nature, extended lifespan, low maintenance and high-power capabilities when compared with rechargeable batteries. These highly suitable characteristics can translate into further extension in applications of SCs in above mentioned areas. During this study, fundamentals of SCs including working principle, electrodes, electrolytes and cell designs have been discussed. Furthermore, advancements of flexible, implantable and wearable electronic devices coupled with the new challenges they face in terms of fulfilling their energy demands to further accelerate their progress has also been reviewed. Finally, suitability of SCs as energy storage devices of choice for FIWEDs has been covered systematically.