A research group at the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has improved the energy storage capacity of graphene supercapacitors using solar heating.
The findings of the research is published in the Journal of Materials Chemistry A.
Meanwhile, in low temperature environments, the impeded diffusion of electrolyte ions seriously restricts electrochemical performance of supercapacitors. The use of materials used in electrodes with solar-thermal properties is expected to provide a new means to solve this challenge.
However, developing electrode materials with excellent solar-thermal properties as well as high energy storage capacity remains a challenge.
The research involved preparing graphene films with three-dimensional porous structures using laser-induction technology. This involved compositing polypyrole uniformly into the graphene network by pulse electrodeposition.
Importantly, this led to the development of graphene/polypyrole composite electrodes, and construction of a new type of solar-thermally enhanced supercapacitor.
The new supercapacitor features several advantages. In the event if temperature drops to -30c, the electrochemical performance of the supercapacitor could be improved rapidly at room temperature below solar irradiation of light intensities of 1.0 kW/m2.
On the other hand, at room temperature, the surface temperature of the devices elevated by 45C for solar irradiation at light intensities of 1.0 Kw/m2.
Following the increase in the temperature of the electrodes, the optimized pore structure and increased electrolyte ion diffusion rate augmented the energy storage capacity by 4.8 times.
Furthermore, since the solid electrolyte is well protected, supercapacitor displayed capacitance retention rate to be 85.8% after 10,000 times of charging and discharging.
The findings of the work provides a direction for solving the temperature challenges of supercapacitors and develop high energy density devices.