Stretchable Aqueous Batteries: Progress and Prospects

Abstract

The development of stretchable electronics is indispensable for realizing next-generation wearable devices, such as sensors, health care devices, and electronic skin. A key challenge for achieving complete and independent wearable devices is developing stretchable power sources. This issue should be addressed appropriately before the realization of wearable devices. Very recently, stretchable aqueous rechargeable batteries as power supplies have received much attention for wearable devices owing to their intrinsic safety and high power density. In this Perspective, we present the current status and the latest advances in research on stretchable aqueous batteries, especially aqueous Li-ion batteries and zinc-based batteries. Also, we briefly provide the design of stretchable materials and battery systems for stretchable aqueous batteries. Furthermore, an overview of general technical issues confronting their development is presented, and a brief discussion on the future outlook of this field is provided.

Recent Progress in the Electrolytes of Aqueous Zinc‐Ion Batteries

“…Polyacrylamide (PAM)-based hydrogel with chemical crosslinking is the mostp romising electrolyte. [14,56] In the PAMh ydrogel matrix, the cross-linking points exist among all the chain segments, resulting in ah ighly porous framework (Figure 5g). [25,47,57] Since the framework structure is connected by chain segments, the PAMh ydrogel electrolyte has excellent mechanical properties.F or PAM-based electrolyte with 2 m ZnSO 4 and 0.1 m MnSO 4 ,t he tensile strengthc an reach 273 kPa and the stretch strain is highert han 3000 %.…”

“…It is known that there are av ariety of functional chains in some polymers. [5,52,56,58] Thus, the smart features of hydrogel electrolytes could be enhanced by introducing the functional groups of polymer chains,i ncluding selfprotecting, self-recovery,s elf-healing and extreme tolerability.…”

A Highly Elastic and Reversibly Stretchable All‐Polymer Supercapacitor

“…To fabricate the fully recoverable stretchable supercapacitor,w ea nnealed af ree-standing pure conducting polymer film as electrode so that the electrodes induced retardance is minimized. [4] This means the reported stretchable supercapacitor device will get longer and longer after acouple of stretching cycles,losing its stretchability rapidly. [1] However,alongneglected issue is the elasticity of devices,t hat is,t he reversible stretchability of stretchable supercapacitors.F lexible supercapacitors can be bent many times,which has been widely demonstrated.…”

“…[2] But for stretchable supercapacitors, researchers usually show that the device can be stretched but never mentioned how many times the device can be stretched. [4] This means the reported stretchable supercapacitor device will get longer and longer after acouple of stretching cycles,losing its stretchability rapidly. [3] It gets worse for ad evice as the electrode materials are usually inorganic materials,which will further hinder geometry recovery of the whole device.…”

Recent Progress in Stretchable Batteries for Wearable Electronics

“…However, these rubbers, which have loose polymer chains and low crystallinity, do not guarantee the battery performance. Intensive research, therefore, should be devoted to developing state‐of‐the‐art materials with high mechanical elongation and low permeability simultaneously …”