抽剩的菸屁股如何促進電動車的發展？南韓科學家找到答案。
「菸屁股材料」勝過奈米碳材？
5位來自首爾國立大學工程學院的科學家，成功將使用過的香菸濾嘴轉變成高效能的超級電容材料，將能用於電動車儲存電力。
不像電池的充電／放電速率有限，超級電容只要短短幾秒鐘就能完成充電，還能為車輛的空調系統、GPS、無線電和其他裝置充電，和用於調整無線電頻率的基本靜電電容相比，超級電容非常適合用於頻繁高電流、短時間充放電的能量儲存裝置。
全世界的科學家都在試圖改善超級電容的性能，包括能量密度、功率密度、循環穩定性，同時努力降低生產成本。碳是以往最常用的超級電容材料，因為其成本低、表面積大、高導電和長期穩定。
不過最新研究顯示，菸屁股材料的效果比目前市面上可取得的碳、石墨和奈米碳管材料都要好。研究者8月5日將研究發表於《奈米科技》期刊。
全球一年5.6兆根 菸屁股再利用減緩環境問題
在首爾科學家的研究中，他們發現香菸濾嘴的醋酸纖維材料，能在富含氮的環境中透過簡單的一步燃燒技術「熱解」轉變成碳基材料。
科學家搜集了萬寶路淺金色、韓國Bohem Cigar Mojito雪茄和韓國煙草人參公司The one Orange的菸屁股進行實驗，將這些香菸在含氬氣和NH3（一種無色、味道刺鼻的氮氫氣體）的空氣中熱解兩小時，產生的碳基材料含有微小奈米孔隙和中型奈米孔隙，改善了其超級電容的特性。
「高效能超級電容材料表面積必須夠大，而材料的表面積可透過增加材料上的小孔增加。不同大小的孔可確保材料具高功率密度。高功率密度是超級電容材料快速充放電的必要條件。」共同作者Jongheop Yi教授說。
研究人員希望菸屁股衍生材料不但能用作超級電容電極的外層塗料，同時解決全球每年製造出數兆根菸屁股的環境問題。根據估計，每年全球產生多達5.6兆根抽過的香菸，換算成重量約766,571噸。
How can used cigarette butts contribute to the development of superior electric vehicles? South Korean researchers have found a way.
Five scientists from Seoul National University’s College of Engineering have converted used cigarette filters into a high-performing material for supercapacitors that could be integrated into electric vehicles to store energy.
Unlike batteries that offer limited charging/discharging rates, supercapacitors require only seconds to charge and can feed electricity back into the vehicle’s air-conditioning system, GPS, radio, and other devices as needed.
Publishing their findings August 5 in the Institute of Physics Publishing’s journal “Nanotechnology,” the scientists say they have demonstrated the material’s superior performance compared to commercially available carbon, graphene and carbon nanotubes.
They hope the material derived from cigarette butts can be used to coat the electrodes of supercapacitors while also offering a solution to the growing environmental problem caused by trillions of used cigarettes filters discarded annually.
It is estimated that as many as 5.6 trillion used-cigarettes, or 766,571 metric tons, are deposited into the environment worldwide every year.
Scientists around the world are currently working towards improving the characteristics of supercapacitors, such as energy density, power density and cycle stability, while reducing production costs.
As compared to the basic electrostatic capacitor used to tune radio frequencies, the supercapacitor is ideal for energy storage that undergoes frequent charge and discharge cycles at high current and short duration.
Carbon is the most popular material that supercapacitors are made of, due to its low cost, high surface area, high electrical conductivity and long-term stability.
In their study, the Seoul researchers demonstrated that the cellulose acetate fibers of which cigarette filters are made could be transformed into a carbon-based material using a simple, one-step burning technique called pyrolysis, conducted in a nitrogen-rich environment.
Used cigarette filters from Marlboro Light Gold, Bohem Cigar Mojito and The one Orange from the Korea Tobacco & Ginseng Corp. were collected.
They were pyrolyzed for two hours in an atmosphere of argon and NH3, a colorless, pungent gas composed of nitrogen and hydrogen.
The carbon-based material resulting from this burning process contained both tiny nano-pores and medium-sized nano-pores, increasing its performance as a supercapacitive material.
“A high-performing supercapacitor material should have a large surface area, which can be achieved by incorporating a large number of small pores into the material,” said co-author Professor Jongheop Yi.
“A combination of different pore sizes ensures that the material has high power densities, which is an essential property in a supercapacitor for the fast charging and discharging,” he said.
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