Fiber electrode shows promise for wearable electronic devices

“The present work is believed [will] spark new insights into the design and fabrication of novel wearable electronic devices from sustainable bioresources”Wei Zhang

With portable and wearable electronic devices becoming increasingly common, much research is being undertaken into renewable biomass as the raw material to develop energy storage devices. The problem is that these tend not to be flexible, cannot be woven into textiles, and can suffer from stress that results in mechanical deformation.

However, a study from Sichuan University in China has developed a new shape recovery electrode material derived from the Juncus effuses (JE), a fiber-shaped plant that grows along the edges of water and marshland throughout the world. They produced a symmetric supercapacitor from the fiber electrodes that can deliver a large specific capacitance, as well as showing its solvent-induced shape recovery properties.

The JE has a unique three-dimensional reticular and hollow tubular microstructure, and its excellent flexibility and compressibility means it can be easily woven into textiles. It is also cheap, flexible and biocompatible with a high specific surface area, offering promise in fields such as water purification, tissue engineering and catalyst support.

As reported in Materials Today Energy [Xia et al. Mater. Today Energy (2020) DOI: 10.1016/j.mtener.2020.100430], the plant was shown to be a sustainable, scalable and versatile electrode for supercapacitors. To provide the material with the capability of storing energy, the team deposited carbon nanotubes and polyaniline on it, making it both flexible and knittable, and with useful shape recovery properties in water and H₂SO₄ solution.

Wearable supercapacitors may experience deformation when subjected to external stress, such as tension, compression, bending and twisting. Hence, shape recovery supercapacitor electrodes are highly desirable to cope with such deformation. This device was able to demonstrate excellent electrochemical stability under deformation as, even if badly damaged, it quickly recovers its original shape once re-immersed in the solvent.

Conventional batteries tend to be bulky and heavy compared to the new generation of wearable electronic devices, and the flexibility and shape recovery supercapacitors developed in this study offer promise for future wearable electronics industry. The gradual replacement of materials from non-renewable fossil fuels with biomass-based ones could considerably relieve both the energy crisis and environmental pollution.

The researchers are currently exploring its potential in the next-generation of wearable and flexible zinc–manganese secondary batteries with a high energy density, and their results suggest that JE could become a powerful resource for applications in electrochemical capacitive devices. As researcher Wei Zhang told Materials Today, “The present work is believed [will] spark new insights into the design and fabrication of novel wearable electronic devices from sustainable bioresources”.