Forget chopped liver: South Korean scientists convert chicken fat into energy storage devices

Chicken fat is what Jews used for many years to improve their chopped liver for a Shabbat meal – until they learned that it contains a ton of cholesterol. 

However, scientists in South Korea have now found that it can be useful for other things, including the production of energy storage devices to meet the need for more sustainable, green energy. Unfortunately, some materials for these devices can be financially and environmentally costly. Producing alternative energy storage devices from things usually thrown away could help resolve these challenges. 

An easy way of synthesizing low-cost carbon nanomaterials without the need for a high-temperature processing approach is critical for energy storage applications because the demand for affordable storage devices has increased. 

The researchers at the School of Mechanical Engineering, Yeungnam University, and colleagues have published in the American Chemical Society’s journal Applied Materials and Interfaces a paper titled “Strategic way of synthesizing heteroatom-doped carbon nano-onions using waste chicken-fat oil for energy storage devices” on how to transform chicken fat into carbon-based electrodes for supercapacitors that store energy and power LEDs.

In 2023, global renewable energy capacity enjoyed an unprecedented almost 50 percent increase versus the previous year, according to the International Energy Agency. But that excess energy must be stored somewhere for the world to benefit from its production later. For example, sunny days in California have recently triggered negative energy prices due to excess supply from rooftop solar panels. 

Recent efforts to design high-performance storage devices have taken advantage of carbon materials, such as graphene, because of their efficient charge transportation and natural abundance. Still, their fabrication is expensive and generates pollution and greenhouse gases. 

The search for alternatives 

Looking for an alternative carbon source material, Mohan Reddy Pallavolu, Jae Hak Jung, Sang Woo Joo, and colleagues wanted to develop a simple, cost-effective method for converting waste chicken fat into electrically conductive nanostructures for supercapacitor energy storage devices.

They first used a gas-flame gun to render the fat from a chicken and burned the melted oil using a flame-wick method, much like an oil lamp. They then collected the soot on the bottom of a flask suspended above the flame. Electron microscopy showed that the soot contained carbon-based nanostructures that were uniform spherical lattices of concentric graphite rings, like the layers of onions. The researchers tested a way to enhance the electrical characteristics of the carbon nanoparticles by soaking them in a solution of thiourea.

Assembled into the negative electrode of an asymmetric supercapacitor, the chicken fat-sourced carbon nanoparticles demonstrated good capacitance and durability, high energy, and power density. As predicted, these properties were improved further when the electrodes were made of the thiourea-treated carbon nanoparticles. The researchers then demonstrated that the new supercapacitor could perform real-time applications – charging and connecting two of them to light up red, green, and blue LEDs. The results highlight the potential advantages of using food waste like chicken fat as a carbon source in search of greener energy.