Power/Performance Bits: April 6

Durian supercapacitors

Researchers from the University of Sydney developed a method that uses durian and jackfruit waste to create supercapacitors.

Supercapacitors are capable of quickly storing and discharging energy. The team says their fruit-based material is more efficient than ones typically made from activated carbon.

“Using durian and jackfruit purchased from a market, we converted the fruits’ waste portions (biomass) into supercapacitors that can be used to store electricity efficiently,” said Vincent Gomes, associate professor at the University of Sydney’s School of Chemical and Biomolecular Engineering.

The team zeroed in on durian and jackfruit because their inherent structure is a good template for porous aerogels.

“Using a non-toxic and non-hazardous green engineering method that used heating in water and freeze drying of the fruit’s biomass, the durian and jackfruit were transformed into stable carbon aerogels — an extremely light and porous synthetic material used for a range of applications,” said Gomes.

“Carbon aerogels make great super-capacitors because they are highly porous. We then used the fruit-derived aerogels to make electrodes which we tested for their energy storage properties, which we found to be exceptional.”

The researchers point to durian waste as a zero-cost substance for naturally-derived super-capacitors that don’t contribute to global warming. Plus, Gomes adds, “the durian and jackfruit supercapacitors perform much better than the materials currently in use and are comparable, if not better, than the expensive and exotic graphene-based materials.”

Organic battery electrodes

Researchers at York University are developing organic electrodes for lithium-based batteries that maintain performance, stability and storage capacity.

“Organic electrode materials are considered to be extremely promising materials for sustainable batteries with high power capabilities,” said Thomas Baumgartner, a professor at York University.

The team created a new carbon-based organic molecule that can replace the cobalt now used in cathodes or positive electrodes in lithium-ion batteries. The new material, electroactive phosphoryl‐bridged viologens (phosphaviologens) composited with single‐walled carbon nanotubes, addresses the shortcomings of the inorganic material while maintaining performance.

“Electrodes made with organic materials can make large‐scale manufacturing, recycling or disposing of these elements more environmentally friendly,” said Baumgartner. “The goal is to create sustainable batteries that are stable and have equally as good if not better capacity.”

The electroactive component good at storing electrical charges and has good long-term stability, making it particularly suitable for batteries.

“We have optimized this electroactive component and put it in a battery. It has a very good voltage, up to the 3.5 volts, which is really where current batteries are now,” Baumgartner said. “It’s an important step forward in making fully organic and sustainable batteries.”

The researchers demonstrated that the material is stable in long-term operation with the ability to charge and discharge for 500 cycles. One of the downsides of inorganic electrodes is that they generate significant heat when charging and require limited discharging rates for safety reasons, but the new molecule addresses that.

The team said their next step is to improve the capacity further. They are currently developing the next generation of molecules that show promise in being able to increase current capacity.