物理化学学报2022，Vol.38Issue(4)：28-37,10.DOI:10.3866/PKU.WHXB202005054
基于混合溶剂有机电解液的超低温孔洞石墨烯超级电容
Ultra-Low-Temperature Supercapacitor Based on Holey Graphene and Mixed-Solvent Organic Electrolyte
摘要
Abstract
Supercapacitors that can withstand extremely low temperatures have become desirable in applications including portable electronic devices,hybrid electric vehicles,and renewable energy conversion systems.Graphene is considered as a promising electrode material for supercapacitors owing to its high specific surface area(up to 2675 m2·g-1)and electrical conductivity(approximately 2×102 S·m-1).However,the restacking of graphene sheets decreases the accessible surface area,reduces the ion diffusion rate and prolongs the ion transport pathways,thereby limiting the energy storage performance at low temperatures(typically＜100 F·g-1 at sub-zero temperatures).Herein,we fabricate a supercapacitor based on holey graphene and mixed-solvent organic electrolyte for ultra-low-temperature applications(e.g.,-60℃).Reduced holey graphene oxide(rHGO)was synthesized as the electrode material via an oxidative-etching process with H2O2.Methyl formate was mixed with propylene carbonate to improve the electrolyte conductivity at temperatures ranging from-60 to 25℃.The as-fabricated supercapacitor showed a high room-temperature capacitance of 150.5 F·g-1 at 1 A·g-1,which was almost 1.5 times greater than that of the supercapacitor using untreated reduced graphene oxide(rGO;101.4 F g-1).The improved capacitance could be attributed to the increased accessible surface rendered by the abundant mesopores and macropores on the holey surface.As the temperature decreased to-60℃,the rHGO supercapacitor still delivered a high capacitance of 106.2 F g-1 with a retention of 70.6％,which was superior to other state-of-the-art graphene-based supercapacitors.Electrochemical impedance spectra tests revealed that the ion diffusion resistance in rHGO was significantly smaller than that in rGO and less influenced by temperature with a lower activation energy.This was because the holey morphology can provide transport pathways for ions and reduce the ion diffusion length during charging/discharging,consequently diminishing the diffusion resistance at low temperatures.Specifically,at-60℃,the energy density of supercapacitor reached up to 26.9 Wh·kg-1 at 1 A·g-1 with a maximum power density of 18.7 kW·kg-1 at 20 A·g-1,surpassing the low-temperature performance of conventional carbon-based supercapacitors.Moreover,after 10000 cycles at-60℃with a current density of 5 A·g-1,89.1％of capacitance was retained,suggesting the stable and reliable power output of the current supercapacitor at extremely low temperatures.关键词
超级电容/超低温/孔洞石墨烯/混合溶剂有机电解液/电化学性能Key words
Supercapacitor/Ultra-low temperature/Holey graphene/Mixed-solvent organic electrolyte/Electrochemical performance分类
化学化工引用本文复制引用
薄拯,孔竞,杨化超,郑周威,陈鹏鹏,严建华,岑可法..基于混合溶剂有机电解液的超低温孔洞石墨烯超级电容[J].物理化学学报,2022,38(4):28-37,10.基金项目
The project was supported by the National Natural Science Foundation of China(51722604),the Zhejiang Provincial Natural Science Foundation of China(LR17E060002),the Key R&D Program of Zhejiang Province,China(2019C01044)and the China Postdoctoral Science Foundation(2019M662048).国家自然科学基金(51722604),浙江省自然科学基金(LR17E060002),浙江省重点研发项目(2019C01044),中国博士后科学基金(2019M662048)资助 （51722604）
