Potassium Ion Batteries with Graphitic Materials

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• 作者：Wei Luo ; Jiayu Wan ; Burak Ozdemir ; Wenzhong Bao ; Yanan Chen ; Jiaqi Dai ; Hao Lin ; Yue Xu ; Feng Gu ; Veronica Barone ; Liangbing Hu
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：November 11, 2015
• 年：2015
• 卷：15
• 期：11
• 页码：7671-7677
• 全文大小：507K
• ISSN：1530-6992

文摘

Graphite intercalation compounds (GICs) have attracted tremendous attention due to their exceptional properties that can be finely tuned by controlling the intercalation species and concentrations. Here, we report for the first time that potassium (K) ions can electrochemically intercalate into graphitic materials, such as graphite and reduced graphene oxide (RGO) at ambient temperature and pressure. Our experiments reveal that graphite can deliver a reversible capacity of 207 mAh/g. Combining experiments with ab initio calculations, we propose a three-step staging process during the intercalation of K ions into graphite: C 鈫?KC₂₄ (Stage III) 鈫?KC₁₆ (Stage II) 鈫?KC₈ (Stage I). Moreover, we find that K ions can also intercalate into RGO film with even higher reversible capacity (222 mAh/g). We also show that K ions intercalation can effectively increase the optical transparence of the RGO film from 29.0% to 84.3%. First-principles calculations suggest that this trend is attributed to a decreased absorbance produced by K ions intercalation. Our results open opportunities for novel nonaqueous K-ion based electrochemical battery technologies and optical applications.