Shi Xiaodong, Zhang Yida, Xu Guofu, Guo Shan, Pan Anqiang, Zhou Jiang, Liang Shuquan
School of Materials Science and Engineering, Central South University, Changsha 410083, China.
National Synchrotron Radiation Laboratory (NSRL), University of Science and Technology of China, Hefei 230029, China.
Sci Bull (Beijing). 2020 Dec 15;65(23):2014-2021. doi: 10.1016/j.scib.2020.07.001. Epub 2020 Jul 3.
Potassium-ion batteries (PIBs) hold great potential as an alternative to lithium-ion batteries due to the abundant reserves of potassium and similar redox potentials of K/K and Li/Li. Unfortunately, PIBs with carbonaceous electrodes present sluggish kinetics, resulting in unsatisfactory cycling stability and poor rate capability. Herein, we demonstrate that the synergistic effects of the enlarged interlayer spacing and enhanced capacitive behavior induced by the co-doping of nitrogen and sulfur atoms into a carbon structure (NSC) can improve its potassium storage capability. Based on the capacitive contribution calculations, electrochemical impedance spectroscopy, the galvanostatic intermittent titration technique, and density functional theory results, the NSC electrode is found to exhibit favorable electronic conductivity, enhanced capacitive adsorption behavior, and fast K ion diffusion kinetics. Additionally, a series of ex-situ characterizations demonstrate that NSC exhibits superior structural stability during the (de)potassiation process. As a result, NSC displays a high reversible capacity of 302.8 mAh g at 0.1 A g and a stable capacity of 105.2 mAh g even at 2 A g after 600 cycles. This work may offer new insight into the effects of the heteroatom doping of carbon materials on their potassium storage properties and facilitate their application in PIBs.
钾离子电池（PIBs）由于钾储量丰富以及K/K和Li/Li具有相似的氧化还原电位，作为锂离子电池的替代品具有巨大潜力。不幸的是，含碳电极的PIBs存在动力学迟缓的问题，导致循环稳定性不理想和倍率性能较差。在此，我们证明了氮和硫原子共掺杂到碳结构（NSC）中所诱导的层间距增大和电容行为增强的协同效应可以提高其钾存储能力。基于电容贡献计算、电化学阻抗谱、恒电流间歇滴定技术以及密度泛函理论结果，发现NSC电极具有良好的电子导电性、增强的电容吸附行为和快速的K离子扩散动力学。此外，一系列非原位表征表明NSC在（脱）钾过程中表现出优异的结构稳定性。结果，NSC在0.1 A g时显示出302.8 mAh g的高可逆容量，即使在2 A g下经过600次循环后仍具有105.2 mAh g的稳定容量。这项工作可能为碳材料的杂原子掺杂对其钾存储性能的影响提供新的见解，并促进其在PIBs中的应用。
