Highly flexible, foldable, and rollable microsupercapacitors on an ultrathin polyimide substrate with high power density

Juan Pu,Xiaohong Wang,Sixing Xu,Kyriakos Komvopoulos,Renxiao Xu

doi:10.1038/s41378-018-0016-3

Abstract

The design and functionality of extremely flexible, foldable, and rollable microsupercapacitors (MSCs) with in-plane interdigital electrodes that consist of single-walled carbon nanotube (SWCNT) networks on an ultrathin polyimide substrate are demonstrated through experiments and finite element simulations. The all-solid-state MSCs can be reversibly bent, folded, and rolled purely elastically without degradation of their electrical performance. The simulation results confirm that the deformation in bent, folded, and rolled MSCs is purely elastic. The high power density (1125 W cm–3) and small time constant (1 ms) of the present MSCs are comparable to those of aluminum electrolytic capacitors. The MSCs operate at scan rates of up to 1000 V s–1, are characterized by a volumetric capacitance of 18 F cm–3 and an energy density of 1.6 mWh cm–3, and exhibit superior electrochemical stability with 96% capacity retention even after 100,000 charge/discharge cycles. The developed MSCs demonstrate high potential for integration in flexible and wearable electronic systems.

Highlights

Electric double-layer capacitors (EDLCs), known as supercapacitors or ultracapacitors, rely on the rapid and reversible adsorption/desorption of ions at the electrode–electrolyte interface for charge storage
Schematic illustrations of a flexible single-walled carbon nanotube (SWCNT) MSC fabricated on an ultrathin PI substrate and its layered structure are shown in Figure 1a, b, respectively
SWCNT MSCs were fabricated on free-standing ultrathin PI substrates by combining conventional lithography and mechanical peel-off techniques

Summary

Introduction

Electric double-layer capacitors (EDLCs), known as supercapacitors or ultracapacitors, rely on the rapid and reversible adsorption/desorption of ions at the electrode–electrolyte interface for charge storage. This kind of charge storage mechanism offers EDLCs several desirable properties including long operation life (>10,000 cycles) and high power density. Because the ionic diffusion paths in 2D in-plane electrodes are much shorter, the rate capability and power performance of the devices can be greatly enhanced[5,6,7] These properties are important when the MSCs are coupled with microbatteries, microfuel cells, and energy harvesters to provide maximum power or when they are used to replace

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