Cao Jinhui, Xu Hanjiao, Zhong Jiang, Li Xiuqi, Li Shengyang, Wang Yaya, Zhang Meng, Deng Hongli, Wang Yiliu, Cui Chunyu, Hossain Mongur, Cheng Yingliang, Fan Ling, Wang Lei, Wang Tao, Zhu Jian, Lu Bingan
State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan Key Laboratory of Two-Dimensional Materials, Hunan University, Changsha 410082, People's Republic of China.
College of Materials Science and Engineering, Hunan University, Changsha 410082, People's Republic of China.
ACS Appl Mater Interfaces. 2021 Feb 24;13(7):8497-8506. doi: 10.1021/acsami.1c00115. Epub 2021 Feb 15.
Potassium-ion hybrid capacitors (KIHCs) have attracted growing attention due to the natural abundance and low cost of potassium. However, KIHCs are still limited by sluggish redox reaction kinetics in electrodes during the accommodation of large-sized K. Herein, a starch-derived hierarchically porous nitrogen-doped carbon (SHPNC) anode and active carbon cathode were rationally designed for dual-carbon electrode-based KIHCs with high energy density. The hierarchical structure and rich doped nitrogen in the SHPNC anode result in a distensible interlayer space to buffer volume expansion during K insertion/extraction, offers more electrochemical active sites to achieve high specific capacity, and has highly efficient channels for fast ion/electron transports. The Raman and TEM demonstrated a reversible electrochemical behavior of the SHPNC anode. Thus, the SHPNC anode delivers superior cycling stability and a high reversible capacity (310 mA h g at 50 mA g). In particular, the KIHCs assembled by the SHPNC anode and commercial active carbon cathode can deliver a high energy density of 165 W h kg at a current density of 50 mA g and an ultra-long cycle life of 10,000 cycles at 1 A g (calculated based on the total mass of the anode and cathode).
钾离子混合电容器（KIHCs）因其钾的天然丰度和低成本而受到越来越多的关注。然而，在容纳大尺寸钾的过程中，KIHCs仍受限于电极中缓慢的氧化还原反应动力学。在此，合理设计了一种淀粉衍生的分级多孔氮掺杂碳（SHPNC）阳极和活性炭阴极，用于基于双碳电极的高能量密度KIHCs。SHPNC阳极中的分级结构和丰富的掺杂氮导致可扩展的层间空间，以缓冲钾插入/脱出过程中的体积膨胀，提供更多的电化学活性位点以实现高比容量，并具有用于快速离子/电子传输的高效通道。拉曼光谱和透射电子显微镜证明了SHPNC阳极具有可逆的电化学行为。因此，SHPNC阳极具有优异的循环稳定性和高可逆容量（在50 mA g时为310 mA h g）。特别是，由SHPNC阳极和商业活性炭阴极组装的KIHCs在50 mA g的电流密度下可提供165 W h kg的高能量密度，在1 A g下具有10000次循环的超长循环寿命（基于阳极和阴极的总质量计算）。
