This scanning electron microscope image shows bee pollen studied for potential use as electrodes for lithium-ion batteries. Color was added to the original black-and-white image. Credit: Purdue University image/ Jialiang Tang
Pollen could represent a boon for battery makers: Recent research has suggested their potential use as anodes in Li-ion batteries. “Our findings have demonstrated that renewable pollens could produce carbon architectures for anode applications in energy storage devices,” said A/Prof Vilas Pol. The anodes in most of today’s lithium-ion batteries are made of graphite. Lithium ions are contained in electrolyte, and these ions are stored in the anode during recharging.
The researchers tested bee pollen- and cattail pollen-derived carbons as anodes. Whereas bee pollen is a mixture of different pollen types collected by honey bees, the cattail pollens all have the same shape. The researchers processed the pollen under high temperatures in a chamber containing argon gas using pyrolysis, yielding pure carbon in the original shape of the pollen particles. They were further processed, or “activated,” by heating at lower temperature ~300 degrees Celsius – in the presence of oxygen, forming pores in the carbon structures to increase their energy-storage capacity.
The research showed the pollen anodes could be charged at various rates. While charging for 10 hours resulted in a full charge, charging them for only 1 hour resulted in more than half of a full charge, Pol said. “The theoretical capacity of graphite is 372 milliamp hours per gram, and we achieved 200 milliamp hours after one hour of charging,” he said.
The researchers tested the carbon at 25 degrees Celsius and 50 degrees Celsius to simulate a range of climates. “This is because the weather-based degradation of batteries is totally different in New Mexico compared to Indiana,” Pol said. Findings showed the cattail pollens performed better than bee pollen. future research will include work to study them in a full-cell battery with a commercial cathode.
http://www.purdue.edu/newsroom/releases/2016/Q1/from-allergens-to-anodes-pollen-derived-battery-electrodes.html
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