National Engineering Research Center of Coal Preparation and Purification, School of Materials and Physics, China University of Mining and Technology, Xuzhou 221116, China; College of Chemical Engineering, China University of Mining and Technology, Xuzhou 221116, China.
National Engineering Research Center of Coal Preparation and Purification, School of Materials and Physics, China University of Mining and Technology, Xuzhou 221116, China; Jiangsu Province Engineering Laboratory of High Efficient Energy Storage Technology and Equipments, School of Materials and Physics, China University of Mining and Technology, Xuzhou 221116, China.
J Colloid Interface Sci. 2023 Oct 15;648:108-116. doi: 10.1016/j.jcis.2023.05.195. Epub 2023 Jun 3.
Graphite anode has great potential toward potassium ion storage for abundant reserves, yet it suffers from the large volume expansion and slow diffusion rate. Herein, the low-cost biochemical fulvic acid-derived amorphous carbon (BFAC) is employed to modify the natural microcrystalline graphite (BFAC@MG) by a simple mixed carbonization strategy. The BFAC smooths the split layer and folds on the surface of microcrystalline graphite and builds the heteroatom-doped composite structure, which effectively alleviates the volume expansion caused by K electrochemical de-intercalation processes, together with improving electrochemical reaction kinetics. As expected, the optimized BFAC@MG-0.5 exhibits superior potassium-ion storage performance, which delivers a high reversible capacity (623.8 mAh g), excellent rate performance (147.8 mAh g at 2 A g), and remarkable cycling stability (100.8 mAh g after 1200 cycles). As a practical device application, the potassium-ion capacitors are assembled using the BFAC@MG-0.5 anode and commercial activated carbon cathode, which exhibits a maximum energy density of 126.48 Wh kg and superior cycle stability. Significantly, this work demonstrates the potential of microcrystalline graphite as the host anode material for potassium-ion storage.
石墨阳极在钾离子存储方面具有巨大的潜力，因为其储量丰富，但它存在体积膨胀大和扩散速率慢的问题。在此，我们采用低成本的生化腐殖酸衍生无定形碳（BFAC），通过简单的混合碳化策略对天然微晶石墨（BFAC@MG）进行修饰。BFAC 能平滑微晶石墨表面的分层和褶皱，并构建杂原子掺杂的复合结构，这有效缓解了钾电化学脱嵌过程中引起的体积膨胀，同时提高了电化学反应动力学。不出所料，优化后的 BFAC@MG-0.5 表现出优异的钾离子存储性能，具有高可逆容量（623.8 mAh g-1）、优异的倍率性能（在 2 A g-1 时为 147.8 mAh g-1）和出色的循环稳定性（1200 次循环后为 100.8 mAh g-1）。作为一种实际的器件应用，我们使用 BFAC@MG-0.5 作为阳极和商业活性炭作为阴极组装钾离子电容器，其能量密度最高可达 126.48 Wh kg-1，且具有出色的循环稳定性。值得注意的是，这项工作展示了微晶石墨作为钾离子存储用宿主阳极材料的潜力。
