Rice husks, the waste product of rice cultivation, might just be the ever-so-needed source of silicon, which could boost the capacity of conventional lithium-ion batteries of smartphones and electric and hybrid vehicles.
Research conducted by a team of Korean scientists and published in the latest issue of the Proceedings of the National Academy of Sciences, presents an innovative approach to converting silica from rice husks into silicon that can be used in Li-ion batteries.
The study was based on the well-established fact that silicon anodes have much greater capacity than their graphite alternatives, however the fading of this capacity makes them much less efficient.
Jang Wook Choi and team looked into ways to preserve the nanoporous structure of silica found in rice husks during the process of extraction of silicon. By adding acid to remove metallic impurities and organic components, followed by reduction using magnesium, the scientists were able to produce silicon, which still has the three-dimensional porous nanostructure. The material was then coated with carbon, making it suitable for use in anodes in lithium coin cells.
The results indicate that the efficiency and the discharge capacity retention of these newly made anodes are much greater. According to the scientists, the reason for this is the formation of stable electrolyte interfaces, which unlike the anodes made from conventional silicon alloys, do not experience high volume change and capacity fading.
Considering that rice is the world’s most widely cultivated crop with 422 million metric tons produced every year, a method that incorporates the use of the waste product to develop advanced technologies, is a real ground-breaker. This is especially the case if it can contribute to an increase in battery capacity of portable electronic devices and hybrid electric vehicles.