Advanced energy materials for flexible batteries in energy storage: A review

Abstract

Smart energy storage has revolutionized portable electronics and electrical vehicles. The current smart energy storage devices have penetrated into flexible electronic markets at an unprecedented rate. Flexible batteries are key power sources to enable vast flexible devices, which put forward additional requirements, such as bendable, twistable, stretchable, and ultrathin, to adapt mechanical deformation under the working conditions. This review summarizes the recent advances in construction and configuration of flexible batteries and discusses the general metrics to benchmark various flexible batteries with different materials and chemistries. Moreover, we present advanced prototype flexible batteries developed by some companies to afford general envision of the technological status. Lastly, the critical points are summarized in the development of flexible batteries and remaining challenges are also presented for the future design of flexible batteries in practical perspectives. K E Y W O R D S composite electrode, flexible batteries, smart energy storage, ultrathin batteries, wearable electronics 1 | INTRODUCTION Rechargeable batteries have popularized in smart electrical energy storage in view of energy density, power density, cyclability, and technical maturity. 1-5 A great success has been witnessed in the application of lithium-ion (Li-ion) batteries in electrified transportation and portable electronics, and non-lithium battery chemistries emerge as alternatives in special applications from cost and safety views. 6-10 While energy/power

Aggregation‐induced emission: Red and near‐infrared organic light‐emitting diodes

“…Organic light‐emitting diodes (OLED) have shown promising prospects in display and illumination fields due to the unique advantages such as self‐emitting displays, transparency, fast response time, light weight, flexibility, and low‐cost fabrication 1–11 . Over the last few decades, great progress has been made in achieving highly efficient OLED devices, resulting in the commercialization of television, smartphone, and wearable devices 12–16 . Wherein, red light is not only an indispensable part of three primary colors for full‐color displays and white OLED but also widely applied in the field of optical telecommunication, information secured devices, night‐vision displays, and bioimaging 17–24 .…”

Incorporation of hydrogen‐bonding units into polymeric semiconductors toward boosting charge mobility, intrinsic stretchability, and self‐healing ability

“…Through molecular design and aggregate structural engineering, the family of conjugated polymers with charge mobility over 10 cm 2 /(V·s) gets an exciting expansion in the past decades 8–10 . For another, unlike inorganic semiconductors and conjugated small molecules, the chain entanglement and multiple weak interactions in thin films of conjugated polymers cooperatively offer conjugated polymers unique superiority of mechanical flexibility with relatively low tensile modulus, which may meet the requirement of emerging flexible electronics such as health monitoring, electronic skin and flexible displaying 11–19 . Currently, further improving charge mobility and promoting conjugated polymers to flexible device are running in the fast lane 20–22 …”

Recent Advances in Y6‐Based Semiconductors: Performance in Solar Cells, Crystallography, and Electronic Structure

“…Historically, the OPV literature of acceptor materials has been dominated by PCBM (1995), [9] next IDTT (2015), [10] and more recently Y6 (2019). [11] In 2019, the advent of Y6, which has the chemical name is 2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-3,9diundecyl-12,13-dihydro- [1,2,5]thiadiazolo [3,4-e]thieno [2",3'':4',5']thieno [2',3':4,5]pyrrolo [3,2-g]thieno [2',3':4,5]-thieno [3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3oxo-2,3-dihydro-1H-indene-2,1-diylidene))dimalononitrile, dramatically improved PCEs to > 17 %, therefore challenging the limitation of fullerene-and IDTT-based OPVs [12] and now dominating the nonfullerene acceptor (NFA) literature. More recent research developments mainly focus on chemical modifications of Y6 to enhance efficiency even further, [13] shed light on the device physics to understand cell operation mechanisms, [5,14] and engineering of the OPV architecture to further improve PCE and stabilize device performance.…”

“…These factors make them expensive and environmentally damaging for future generations to utilize. Solar energy is one of the most powerful renewable clean energy resources, [1] and can be efficiently collected by several types of devices, [2] including solar cells [3] . Compared with traditional inorganic semiconductors, [4] organic solar cells [5] based on solution‐processed photoactive layers comprising an organic/polymeric donor and a small molecule acceptor semiconductors sandwiched between two vertical metal/metal oxide electrodes, can efficiently produce electricity from solar energy.…”