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Edge-Plane Exposed N-Doped Carbon Nanofibers Toward Fast K-Ion Adsorption/Diffusion Kinetics for K-Ion Capacitors
CCS Chemistry ( IF 9.4 ) Pub Date : 2020/5/12 , DOI: 10.31635/ccschem.020.201900103
Zheng Yi 1 , Song Jiang 1 , Yong Qian 1 , Jie Tian 2 , Ning Lin 1 , Yitai Qian 1
Affiliation  

Sluggish kinetics severely limit the development of potassium-ion hybrid capacitors (PIHCs). Exposing active sites is recognized as an ideal strategy to resolve this issue, but the corresponding material design is challenging. Herein, carbon nanofibers with abundant, exposed edge-plane active sites due to (002) orientation adjustment were developed by a molten salt-assisted procedure. Importantly, due to the radial (002) orientation with more active edge-plane sites to adsorb K and shorten the K diffusion distance, the obtained carbon nanofibers harvest improved K adsorption/diffusion kinetics. Meanwhile, theoretical calculations indicate that the synchronically introduced N-doped defects can also lower the diffusion barrier and enhance K adsorption kinetics. Ex situ characterizations and electrochemical studies prove the improved kinetics that significantly improve the K storage properties of the obtained carbon nanofibers. Hence, a high cycling capacity of 252.8 mAh g?1 at 100 mA g?1 after 500 cycles and rate capacity of 181.5 mAh g?1 at 1000 mA g?1 after 1200 cycles have been achieved. Remarkably, the as-developed PIHCs deliver an energy density of 170 Wh kg?1 over 1–4 V, along with capacity retention of 81.6% at 2000 mA g?1 after 10,000 cycles.

中文翻译:

边缘平面暴露的N掺杂碳纳米纤维对K离子电容器的快速K离子吸附/扩散动力学。

动力学迟缓严重限制了钾离子混合电容器(PIHC)的开发。公开活动站点是解决此问题的理想策略,但相应的材料设计具有挑战性。在此,通过熔融盐辅助方法开发了由于(002)取向调节而具有丰富的暴露的边缘平面活性部位的碳纳米纤维。重要的是,由于径向(002)方向具有更多的活动边缘平面位置来吸附K和缩短K扩散距离,因此获得的碳纳米纤维收获了改善的K吸附/扩散动力学。同时,理论计算表明,同步引入的N掺杂缺陷也可以降低扩散势垒,增强K吸附动力学。异位表征和电化学研究证明了改善的动力学,该动力学显着改善了获得的碳纳米纤维的K储存性能。因此,在500次循环后,在100mA g·1下具有252.8mAh g·1的高循环容量,在1200次循环后在1000mA·g-1下获得了181.5mAh g·1的倍率容量。值得注意的是,已开发的PIHC在1-4 V电压下的能量密度为170 Wh kg?1,在10,000次循环后在2000 mA g?1下的容量保持率为81.6%。
更新日期:2020-09-16
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