Reuters – Millions of us drink coffee for its energy kick. But researchers in Taiwan say it could one day help power our smartphones, laptops and even electric vehicles. Tsai Hsing-yu, a student at Chung Yuan Christian University, has created a coin cell battery that draws its power from discarded coffee grounds that she sources from coffee shops around campus.
Liu Wei-Jen, associate professor at the university’s chemical engineering department, had the initial idea for the project after noticing the amount of coffee consumed by the Taiwanese public. He said graphite, the conventional source material, is much costlier, possibly making this research a viable start-up business in the future.
“The costs for natural and artificial graphite are both relatively high, so we are hoping to find a replacement substance,” Liu said. “Because graphite and coffee grounds are both carbon, I wondered if there was the possibility to create a source material for the use in batteries through modification of the carbon.”
His team has already applied for patents in Taiwan, China, and the U.S., while companies have expressed initial interest in developing the technology.
The source material for the coin cells is a mix of discarded coffee grounds and a substance that the student and her professor prefer to keep a secret. The mixture is ground down to fine powder and heated in a furnace before being mixed with a fluid and spread onto a copper sheet. Round shapes from the sheet are placed into coin cell components with other conductive materials.
Producing the coin cells uses less energy than conventional methods, according to Tsai, as the coffee grounds mixture only needs to be heated to 800 degrees Celsius, compared to the up to 2,800 degrees that other source materials require. Using discarded coffee powder also contributes to making the process more environmentally friendly.
According to statistics quoted by Liu, Taiwanese drink around 2.8 billion cups of coffee per year, making coffee grounds an attractive source material for batteries and other products due to its easy and cheap accessibility. It also makes production cheaper. The price of button cell lithium batteries on the Taiwan market ranges from NT$20 to NT$25 (about 60 to 80 U.S. cents), while the team claims that their design can reduce prices to less than NT$20 per battery.
But before the team can think of upscaling their production efforts, further tests have to be made as the coin cells still lag behind conventional versions. In 18 months of research, they’ve so far only been able to withstand 100 charging cycles as compared to the normal 500 cycles of conventional lithium batteries.