Potassium Ion Batteries with Graphitic Materials
Potassium Ion Batteries with Graphitic Materials
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DOI：
10.1021/acs.nanolett.5b03667
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发表时间：
2015-11-01
期刊：
影响因子：
10.8
通讯作者：
Hu, Liangbing
中科院分区：
文献类型：
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作者：
Luo, Wei;Wan, Jiayu;Hu, Liangbing
石墨层间化合物（GIC）由于其特殊的性能而引起了人们的极大关注，这些性能可以通过控制插层物种和浓度来进行微调。在这里，我们首次报道了钾（K）离子可以在环境温度和压力下电化学嵌入石墨材料，如石墨和还原氧化石墨烯（RGO）。我们的实验表明，石墨可以提供207 mAh/g的可逆容量。结合实验和从头计算，我们提出了一个三步阶段过程中的K离子插入石墨：C -> KC 24（阶段III）-> KC 16（阶段II）-> KC 8（阶段I）。此外，我们发现K离子也可以嵌入到RGO膜中，具有更高的可逆容量（222 mAh/g）。我们还发现K离子的插入可以有效地提高RGO薄膜的光学透过率，从29.0%提高到84.3%。第一性原理计算表明，这种趋势是由于K离子嵌入产生的吸光度降低。我们的研究结果为新型非水K离子电化学电池技术和光学应用提供了机会。
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 --> KC24 (Stage III) --> KC16 (Stage II) --> 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.