Skin-Like, Dynamically Stretchable, Planar Supercapacitors with Buckled Carbon Nanotube/Mn–Mo Mixed Oxide Electrodes and Air-Stable Organic Electrolyte

Abstract

For practical applications of high-performance supercapacitors as wearable energy storage devices attached to skin or clothes, the supercapacitors are recommended to have stable mechanical and electrochemical performances during dynamic deformations, including stretching, due to real-time movements of the human body. In this work, we demonstrate a skin-like, dynamically stretchable, planar supercapacitor (SPS). The SPS consists of buckled manganese/molybdenum (Mn/Mo) mixed oxide@multiwalled carbon nanotube (MWCNT) electrodes; organic gel polymer electrolyte of adiponitrile, succinonitrile, lithium bis­(trifluoromethanesulfonyl)­imide, and poly­(methyl methacrylate); and a porous, elastomeric substrate. The addition of an Mn/Mo mixed oxide to the MWCNT film produces an 8-fold increase in the areal capacitance. The use of an organic solvent-based electrolyte enhances the operation cell voltage to 2 V and air stability to one month under ambient air conditions. The fabricated planar supercapacitors are biaxially stretchable up to 50% strain and maintain ∼90% of their initial capacitance after 1000 repetitive stretching/releasing cycles. Furthermore, the SPS exhibits stable electrochemical performance under dynamic stretching in real time regardless of the strain rate and performs reliably during repetitive bending/spreading motions of an index finger while attached to skin.

3D‐Printed Stretchable Micro‐Supercapacitor with Remarkable Areal Performance

“…Figure 4h compares the areal energy and power density values of the MXene‐AgNW‐MnONW‐C60 MSC with previously reported stretchable MSCs . It exhibited a high areal energy density of 19.2 µWh cm −2 at a power density of 0.86 mW cm −2 , and 6.47 µWh cm −2 at a high power density of 58.3 mW cm −2 .…”

“…Figure 5e shows a comparison of the capacitance of the MXene‐AgNW‐MnONW‐C60 MSC at different stretching states with that of the state‐of‐the‐art stretchable MSCs. Our MSC withstands high strain while exhibiting much higher areal capacitance than all reported stretchable MSCs . To further evaluate the applicability of the MXene‐AgNW‐MnONW‐C60 MSC to wearable devices, its performance was also evaluated upon bending.…”

“…In the second, tortuous finger electrodes were designed and adhered to a pre‐strained elastic substrate, allowing the resulting wrinkled structure to be flattened out to release strain when stretched . Over the past several years, various techniques based on these two strategies have been successfully implemented to produce stretchable MSCs with remarkable stretchability to accommodate complex deformations or withstand applied strain above 100% . However, to enable the practical operation of wearable on‐chip microdevices, two fundamental hurdles remain to be addressed.…”

A Facile Fabrication and Transfer Method of Vertically Aligned Carbon Nanotubes on a Mo/Ni Bilayer for Wearable Energy Devices

“…The calculated strain is ≈0.2%, and the resistance is maintained stable during the cyclic bending test (Figure 2k). When they are combined with appropriate structures or patterns, such as the buckled wavy structure, [ 27,28 ] serpentine patterns, [ 29 ] or micro‐cracked film structure, [ 30 ] they can become stretchable. [ 31,32 ]…”

A Shape Memory High‐Voltage Supercapacitor with Asymmetric Organic Electrolytes for Driving an Integrated NO2 Gas Sensor

“…Therefore, it is of significance to develop supercapacitors with shape memory as well as high electrochemical performances. The voltage range of the supercapacitor can be increased by constructing asymmetric electrodes or by using of organic solvent–based electrolytes …”