Italian researchers have developed a supercapacitor from graphene and copper that can be integrated into fabrics  

Now that almost everyone has a smartphone, the race is on to find the ‘next big thing’. Thanks to recent improvements in materials and electronics, wearable technologies may well be it. From health and fitness tackers, to light-up jackets, the market for wearables is predicted to grow from over $14 billion in 2014 to $70 billion in 2024 (IDTechEx). But they still face issues around energy storage – specifically, how to integrate traditionally bulky batteries or capacitors into lightweight, flexible devices.

In a paper published in Carbon [DOI: 10.1016/j.carbon.2016.05.003], Italian researchers report on a graphene-based supercapacitor wire that can be woven into textiles. They used a hydrothermal reaction to synthesise a 3D graphene network, in-situ, around a copper wire. The wire was submerged in a solution of graphene oxide powder and autoclaved, before being rapidly frozen and dried overnight. The reduced graphene oxide (rGO) self-assembled into a graphene aerogel that covered the copper (Cu) wire completely – a loading of 200 mg/cm of active material was observed. Two of the as-prepared rGO@Cu wires were then dip-coated in polyvinylpyrrolidone (PVP) before being manually assembled in a two-wire parallel configuration and heated to form a single structure.

A 5cm-long section of the superconducting wire assembly was inserted into a loosely-woven cotton fabric and its electrical performance tested. The specific capacitance per unit length was found to be 12.5 mF/cm, which means it outperformed all previously results reported in the literature. It also displayed very good electrical stability, maintaining 95% of its initial capacitance after 10,000 charge-discharge cycles. The authors suggest that the use of graphene rather than bulk carbon allowed for an increased energy density without decreasing the power density.

Cross-sections of the assembly were produced by Focused Ion Beam (FIB) milling, to examine the interfaces between the polymer, the porous 3D graphene network and the copper wire. rGO aerogel was found to show good adhesion to the copper wire, and this was partly attributed to the formation of a copper-oxide layer between the two materials. Mechanically too, the superconducting wire assembly impressed. Thanks to its strong C-C bonds, it withstood repeated bending and folding without any significant deterioration of specific capacitance. In fact, it retained almost 99% of ‘flat-sample’ capacitance after 1000 cycles of extreme bending (up to 160°). These supercapacitors have certainly created a lot of interest, and may well represent a leap forward in energy storage systems for e-textiles.


A. Lamberti, A. Gigot, S. Bianco, M. Fontana, M. Castellino, E. Tresso, C.F. Pirri, “Self-assembly of graphene aerogel on copper wire for wearable fiber-shaped supercapacitors”, Carbon 105 (2016) 649-654. DOI: 10.1016/j.carbon.2016.05.003