Researchers from the Digital Cellulose Center in Sweden have developed a paper supercapacitor that can store renewable energy on a large scale, and as efficiently as conventional, commercial supercapacitors.
“Our energy demand will only increase, and we need new technologies to store renewable energy sustainably,” said Dr. Jesper Edberg, Scientific Leader at the Digital Cellulose Center and Researcher at RISE, Sweden. “We aim to create sustainable, renewable and reusable electronics, and this is a prime example of how we, in the near future, can create green storage for green energy.”
The researchers developed a printed supercapacitor by replacing the plastic substrates with paper, making it more sustainable. The paper is coated with aluminum, functioning both as the device’s current collector and as a barrier for moisture and oxygen. Now research focuses on increasing its capacitance and voltage. Individual devices show capacitance of 10F, with a ‘sheet’ of them increasing it to 127.8F, or 332.8mF/cm2. Connecting several of these supercapacitors in series increases the operating voltage; for example, a device showed charging behaviour up to 5V when four individual paper supercapacitors were arranged in series.
“The capacitance of the paper supercapacitor is approximately equivalent to commercial supercapacitors when normalised against volume,” said Dr. Jesper Edberg, part of the supercapacitor research team.
The Swedish team believes that, in the near future, businesses and society will need to store energy on-site, and these energy storage devices could, for instance, be built into the walls of buildings to store energy locally from solar cells on the roof, while at the same time functioning as insulation for the building:
“One of the advantages of the paper device is how it is manufactured, which we believe can lead to faster production. It is also thin, foldable and bendable and can be integrated into new environments where the cylindrical-shaped, metal commercial supercapacitors do not fit.”
Another benefit of this paper energy storage device is that it can be customised; after it is screen printed, it can be cut and connected in specific ways to power various applications. For small electronic devices that require minimal power, an individual sheet of this energy storage device will suffice, whereas to power something bigger, the devices, or sheets of them, can be connected in series to increase their voltage or capacitance.
