Three-dimensional graphene materials have been studied as typical supercapacitors electrode materials by virtue of their ultrahigh specific surface area and good ion transport capacity.However,improvement of the poor ...Three-dimensional graphene materials have been studied as typical supercapacitors electrode materials by virtue of their ultrahigh specific surface area and good ion transport capacity.However,improvement of the poor volumetric electrochemical performance of these graphene materials has been required although they have high gravimetric energy density.In this work,nanocellulose/nitrogen and fluorine co-doped graphene composite hydrogels(NC-NFGHs)were prepared through a convenient hydrothermal approach utilizing ammonium fluoride as the heteroatom source.Nanocellulose(NC)and high concentration of graphene oxide(GO)were utilized to adjust the structure of NC-NFGHs and increase their packing density.Subsequently,the aqueous symmetric supercapacitor based on NC-NFGH-80 exhibits remarkable gravimetric(286.6 F·g^(-1))and volumetric(421.3 F·cm^(-3))specific capacitance at 0.3 A·g^(-1),good rate performance,and remarkable cycle stability up to 10,000 cycles.Besides,the all-solid-state flexible symmetric supercapacitors(ASSC)fabricated by NC-NFGH-80 also delivered a large specific capacitance of 117.1 F·g^(-1)at 0.3 A·g^(-1)and long service life over 10,000 cycles at 10 A·g^(-1).This compact porous structure and heteroatom co-doped graphene material supply a favorable strategy for high-performance supercapacitors.展开更多
具有高体积能量密度的钾离子电池有望成为下一代的低成本能源存储设备.金属铋具有较高的理论容量(3763 mA h cm^−3)和相对较低的工作电位(−2.93 Vvs.SHE),是一种很有前途的钾离子电池负极材料.但铋在与钾的合金化过程中,会产生大的体积...具有高体积能量密度的钾离子电池有望成为下一代的低成本能源存储设备.金属铋具有较高的理论容量(3763 mA h cm^−3)和相对较低的工作电位(−2.93 Vvs.SHE),是一种很有前途的钾离子电池负极材料.但铋在与钾的合金化过程中,会产生大的体积膨胀,导致电极容量严重衰减.本文报道了一种柔性、自支撑的铋纳米片/石墨烯复合物电极膜,该电极膜具有优化的孔隙率,可满足电极循环过程中的体积膨胀.此外,该电极中优化的孔隙结构改善了循环过程中的电子和离子输运,并提高了电极在钾化和去钾化过程中的结构稳定性,使其具有良好的电化学储钾性能.特别是,在电流密度为0.5 A g^−1的情况下,该电极的体积容量可以达到451 mA h cm^−3,明显优于之前报道的商用石墨材料.展开更多
基金The authors gratefully acknowledge the support from the National Natural Science Foundation of China(No.52072191)Heilongjiang Provincial Natural Science Foundation of China(No.LH2020E126)the Fundamental Research Fund of Heilongjiang Provincial University(No.135509204).
文摘Three-dimensional graphene materials have been studied as typical supercapacitors electrode materials by virtue of their ultrahigh specific surface area and good ion transport capacity.However,improvement of the poor volumetric electrochemical performance of these graphene materials has been required although they have high gravimetric energy density.In this work,nanocellulose/nitrogen and fluorine co-doped graphene composite hydrogels(NC-NFGHs)were prepared through a convenient hydrothermal approach utilizing ammonium fluoride as the heteroatom source.Nanocellulose(NC)and high concentration of graphene oxide(GO)were utilized to adjust the structure of NC-NFGHs and increase their packing density.Subsequently,the aqueous symmetric supercapacitor based on NC-NFGH-80 exhibits remarkable gravimetric(286.6 F·g^(-1))and volumetric(421.3 F·cm^(-3))specific capacitance at 0.3 A·g^(-1),good rate performance,and remarkable cycle stability up to 10,000 cycles.Besides,the all-solid-state flexible symmetric supercapacitors(ASSC)fabricated by NC-NFGH-80 also delivered a large specific capacitance of 117.1 F·g^(-1)at 0.3 A·g^(-1)and long service life over 10,000 cycles at 10 A·g^(-1).This compact porous structure and heteroatom co-doped graphene material supply a favorable strategy for high-performance supercapacitors.
基金supported by the National Nature Science Foundations of China (Grant No. 21673263, and 51572247)the Shandong Province Natural Science Foundation (Grant No. ZR2014EMM003)the Independent Innovation Plan Foundations of Qingdao City of China (Grant No. 16-5-1-42-jch)
基金This work was supported by the National Natural Science Foundation of China(51902176)China Postdoctoral Science Foundation(2018M631462)+1 种基金Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C341)Shenzhen Municipal Development and Reform Commission and the Development and Reform Commission of Shenzhen Municipality for the development of the“Low-Dimensional Materials and Devices”Discipline.
文摘具有高体积能量密度的钾离子电池有望成为下一代的低成本能源存储设备.金属铋具有较高的理论容量(3763 mA h cm^−3)和相对较低的工作电位(−2.93 Vvs.SHE),是一种很有前途的钾离子电池负极材料.但铋在与钾的合金化过程中,会产生大的体积膨胀,导致电极容量严重衰减.本文报道了一种柔性、自支撑的铋纳米片/石墨烯复合物电极膜,该电极膜具有优化的孔隙率,可满足电极循环过程中的体积膨胀.此外,该电极中优化的孔隙结构改善了循环过程中的电子和离子输运,并提高了电极在钾化和去钾化过程中的结构稳定性,使其具有良好的电化学储钾性能.特别是,在电流密度为0.5 A g^−1的情况下,该电极的体积容量可以达到451 mA h cm^−3,明显优于之前报道的商用石墨材料.
