Recent Advances in Flexible Wearable Supercapacitors: Properties, Fabrication, and Applications

Abstract

A supercapacitor is a potential electrochemical energy storage device with high‐power density (PD) for driving flexible, smart, electronic devices. In particular, flexible supercapacitors (FSCs) have reliable mechanical and electrochemical properties and have become an important part of wearable, smart, electronic devices. It is noteworthy that the flexible electrode, electrolyte, separator and current collector all play key roles in overall FSCs. In this review, the unique mechanical properties, structural designs and fabrication methods of each flexible component are systematically classified, summarized and discussed based on the recent progress of FSCs. Further, the practical applications of FSCs are delineated, and the opportunities and challenges of FSCs in wearable technologies are proposed. The development of high‐performance FSCs will greatly promote electricity storage toward more practical and widely varying fields. However, with the development of portable equipment, simple FSCs cannot satisfy the needs of integrated and intelligent flexible wearable devices for long durations. It is anticipated that the combining an FSC and a flexible power source such as flexible solar cells is an effective strategy to solve this problem. This review also includes some discussions of flexible self‐powered devices.

Advancements in stretchable organic optoelectronic devices and flexible transparent conducting electrodes: Current progress and future prospects

“…FSCs can exhibit a variety of features and abilities depending on the components used, including compressibility, stretchability, bendability, and twisting. FSCs have distinct properties that make them appropriate for many applications [ 48 ]. The major priority of flexible capacitor design is the development of flexible electrode materials for FESC manufacture.…”

Pseudocapacitive Kinetics in Synergistically Coupled MoS2–Mo2N Nanowires with Enhanced Interfaces toward All-Solid-State Flexible Supercapacitors

“…Flexible, efficient, and fast-charging energy storage devices have recently sparked tremendous interest, owing to their potential applications in futuristic wearable and rollable electronics. In particular, researchers have focused on developing high-energy density flexible supercapacitors (FSCs) with fast-charging capabilities to bridge the gap between traditional batteries and capacitors. − FSCs outperform the conventional energy storage devices ascribed primarily to their superior power density (>10 kW·kg –1 ), longer stable lifecycle (>10,000 cycles), environmentally sustainable attributes, and ability to sustain repeated flexing while being simultaneously charged-discharged without any degradation. Nevertheless, FSC possesses a substantially inferior energy density compared to traditional Li-ion batteries, which restrains their utilization and fabrication on a large scale. − In this regard, materials that exhibit “Pseudocapacitance” can potentially assist in realizing FSCs with higher energy and power densities simultaneously.…”

“…In particular, researchers have focused on developing high-energy density flexible supercapacitors (FSCs) with fast-charging capabilities to bridge the gap between traditional batteries and capacitors. − FSCs outperform the conventional energy storage devices ascribed primarily to their superior power density (>10 kW·kg –1 ), longer stable lifecycle (>10,000 cycles), environmentally sustainable attributes, and ability to sustain repeated flexing while being simultaneously charged-discharged without any degradation. Nevertheless, FSC possesses a substantially inferior energy density compared to traditional Li-ion batteries, which restrains their utilization and fabrication on a large scale. − In this regard, materials that exhibit “Pseudocapacitance” can potentially assist in realizing FSCs with higher energy and power densities simultaneously. Pseudocapacitive materials operate on rapid, highly reversible surface-controlled faradaic and intercalation kinetics coupled with electric double-layer capacitive (EDLC) mechanisms, resulting in significantly higher charge-storage capacities at ultrafast rates. , …”

Pseudocapacitance Powered Nickel Molybdenum Nitride Nanocomposite Reactively Cosputtered on Stainless-Steel Mesh toward Advanced Flexible Supercapacitors

“…Flexible supercapacitors (FSCs) featuring high energy density have recently witnessed tremendous interest in the research community owing to the increasing popularity of foldable smartphones, wearable fitness trackers, and rollable-screen televisions. FSCs provide ultrafast charging–discharging rates (>10 kW kg –1 ), longer cycle life (>10,000 cycles), and superior efficiency (>95%) while displaying state-of-the-art flexibility and stability at various deformation conditions, making their integration highly suitable in flexible electronics. − Conventional battery technology is limited by lower power density (<1 kW kg –1 ) and shorter cycle life (1000–2000 cycles), restraining their applicability in modern fast-charging devices. On the other hand, commercial carbon-based supercapacitors suffer from lower energy density and lack flexibility characteristics. − In this aspect, pseudocapacitive materials that undergo fast and reversible Faradaic redox reactions at or near the electrode’s surface combined with electric double-layer capacitive (EDLC) kinetics have the potential to deliver significantly greater energy density and power density simultaneously. ,, …”