Sun Yongwen, Xiao Hao, Li Haibo, He Yezeng, Zhang Ya, Hu Yi, Ju Zhicheng, Zhuang Quanchao, Cui Yanhua
The Jiangsu Province Engineering Laboratory of, High Efficient Energy Storage Technology and Equipments, School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou, 221116, P.R. China.
School of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng, 252059, P.R.China.
Chemistry. 2019 May 28;25(30):7359-7365. doi: 10.1002/chem.201900448. Epub 2019 Apr 26.
Although the insertion of potassium ions into graphite has been proven to be realistic, the electrochemical performance of potassium-ion batteries (PIBs) is not yet satisfactory. Therefore, more effort is required to improve the specific capabilities and achieve a long cycling life. The mild carbonization process in molten salt (NaCl-KCl) is used to synthesize nitrogen/oxygen co-doped hierarchically porous carbon (NOPC) for PIBs by using cyanobacteria as the carbon source. This exhibits highly reversible capacities and ultra-long cycling stability, retaining a capacity of 266 mA h g at 50 mA g (100 cycles) and presents a capacity of 104.3 mA h g at 1000 mA g (1000 cycles). Kinetics analysis reveals that the potassium ion (K ) storage of NOPC is controlled by a capacitive process, which plays a crucial role in the excellent rate performance and superior reversible ability. The high proportion of capacitive behavior can be ascribed to the hierarchically porous structure and improved conductivity resulting from nitrogen and oxygen doping. Furthermore, density functional theory (DFT) calculations theoretically validate the enhanced potassium storage effect of the as-obtained NOPC. More importantly, the route to NOPC from cyanobacteria in molten salt provides a green approach to the synthesis of porous carbon materials.
尽管已证明将钾离子插入石墨是可行的，但钾离子电池（PIBs）的电化学性能仍不尽人意。因此，需要付出更多努力来提高比容量并实现长循环寿命。采用温和的熔盐（NaCl-KCl）碳化工艺，以蓝细菌为碳源合成用于PIBs的氮/氧共掺杂分级多孔碳（NOPC）。该材料表现出高度可逆的容量和超长的循环稳定性，在50 mA g（100次循环）下容量保持在266 mA h g，在1000 mA g（1000次循环）下容量为104.3 mA h g。动力学分析表明，NOPC的钾离子（K⁺）存储受电容过程控制，这对优异的倍率性能和卓越的可逆能力起着关键作用。电容行为的高占比可归因于分级多孔结构以及氮氧掺杂导致的导电性提高。此外，密度泛函理论（DFT）计算从理论上验证了所得NOPC增强的钾存储效果。更重要的是，在熔盐中由蓝细菌制备NOPC的路线为多孔碳材料的合成提供了一种绿色方法。
