F-doping hard carbon(F–HC)was synthesized through a mild fluorination at temperature at relative low temperature as the potential anode for sodium-ion batteries(SIBs).The F-doping treatment to HC expands interlayer d...F-doping hard carbon(F–HC)was synthesized through a mild fluorination at temperature at relative low temperature as the potential anode for sodium-ion batteries(SIBs).The F-doping treatment to HC expands interlayer distance and creates some defects in the graphitic framework,which has the ability to improve Na+storage capability through the intercalation and pore-filling process a simultaneously.In addition,the electrically conductive semi-ionic C–F bond in F–HC that can be adjusted by the fluorination temperature facilitates electron transport throughout the electrode.Therefore,F–HC exhibits higher specific capability and better cycling stability than pristine HC.Particularly,F–HC fluorinated at 100℃ (F–HC100)delivers the reversible capability of 343 mAh/g at 50 mAh/g,with the Coulombic efficiency of 78.13%,and the capacity retention remains as 95.81%after 100 cycles.Moreover,the specific capacity of F–HC100 returns to 340 mAh/g after the rate capability test demonstrates its stability even at high current density.The enhanced specific capacity of F–HC,especially at low-voltage region,has the great potential as the anode of SIBs with high energy density.展开更多
作为电池的重要组成部分,电解质在很大程度上影响着锂电池的安全性、温度适应性、充放电性能和循环寿命。研究合成了二氟草酸硼酸锂(LiODFB)-N-甲基-N-甲氧基乙基吡咯烷双(三氟磺酰亚胺)(Pyr1,2O1TFSI)/亚硫酸酯电解质,展现出良好的离...作为电池的重要组成部分,电解质在很大程度上影响着锂电池的安全性、温度适应性、充放电性能和循环寿命。研究合成了二氟草酸硼酸锂(LiODFB)-N-甲基-N-甲氧基乙基吡咯烷双(三氟磺酰亚胺)(Pyr1,2O1TFSI)/亚硫酸酯电解质,展现出良好的离子传导性、电极相容性和宽工作温度范围,其中LiODFB-Pyr1,2 O 1TFSI/DMS电解质体系的电导率和锂离子迁移数分别为8.163×10^(-3)S·cm^(-1),0.28。首次将离子液体基电解质体系的应用温度范围拓展到-40℃,使Li/MCMB电池和Li/LiFePO_4电池在-40~60℃的工作温度范围内均表现出理想的电化学性能。以Li[N(SO_2CF_3)_2](LiTFSI)作为锂盐,将三(乙二醇)二甲醚(TEGDME)作为共溶剂,结合离子液体Pyr1,2O 1TFSI,制备系列Li/S电池电解质。含Li TFSI-(70 wt%)Pyr1,2 O 1TFSI/(30 wt%)TEGDME电解质的Li/S电池表现出优秀的循环性能和倍率性能,在0.1 C充放电倍率下,首周循环周期放电比容量1 212.8 m Ah·g^(-1),循环100周后仍然维持在693.5 m Ah·g^(-1)。在1 C放电倍率下,循环100周放电比容量约为827.3m Ah·g^(-1),库伦效率达到99%以上。同时,该电解质还具有良好的高温性能,电池在80℃仍然可以正常工作,放电容量达1 005.3 m Ah·g^(-1)。在总结相关研究工作的基础上,从离子液体/有机共溶剂电解质体系出发,首次半定量对离子液体/共溶剂体系和电化学基本性质间的构效关系进行了深入分析,对未来面向不同应用方向的锂二次电池电解质体系的设计合成具有一定的理论意义和参考价值。展开更多
In this paper,porous partially fluorinated graphene(PFG)for supercapacitors(SCs)was fabricated by a mild and secure one-pot hydrothermal method utilizing weakly coordinating anion BF_(4)^(-) as the fluorine source.The...In this paper,porous partially fluorinated graphene(PFG)for supercapacitors(SCs)was fabricated by a mild and secure one-pot hydrothermal method utilizing weakly coordinating anion BF_(4)^(-) as the fluorine source.The hydrolysis rate of sodium fluoroborate was adjusted by controlling the reaction temperature and PFG containing semi-ionic C-F bonds was obtained,where the content of semi-ionic C-F bonds in PFG can be easily regulated.The final experimental results show that the incorporation of fluorine not only modulates the electrochemical properties of the material,but also creates abundant pores.When assembled in a symmetric supercapacitor,the PFG shows a high specific capacitance of 269.7 F g^(-1) at 1 A g^(-1) and a superior rate capability with 89.3%capacitance retained,as the current density is increased from 1 A g^(-1)even to 20 A g^(-1).Furthermore,the resultant energy density for PFG is 9.4 Wh kg^(-1) at a power density of 250.0 W kg^(-1)(1 A g^(-1)).All these results confirm that as-prepared partially fluorinated graphene is appropriate for the application in SCs and mass production.展开更多
基金financially supported by the State Grid Headquarters Science and Technology Project(No.5455DW190009)。
文摘F-doping hard carbon(F–HC)was synthesized through a mild fluorination at temperature at relative low temperature as the potential anode for sodium-ion batteries(SIBs).The F-doping treatment to HC expands interlayer distance and creates some defects in the graphitic framework,which has the ability to improve Na+storage capability through the intercalation and pore-filling process a simultaneously.In addition,the electrically conductive semi-ionic C–F bond in F–HC that can be adjusted by the fluorination temperature facilitates electron transport throughout the electrode.Therefore,F–HC exhibits higher specific capability and better cycling stability than pristine HC.Particularly,F–HC fluorinated at 100℃ (F–HC100)delivers the reversible capability of 343 mAh/g at 50 mAh/g,with the Coulombic efficiency of 78.13%,and the capacity retention remains as 95.81%after 100 cycles.Moreover,the specific capacity of F–HC100 returns to 340 mAh/g after the rate capability test demonstrates its stability even at high current density.The enhanced specific capacity of F–HC,especially at low-voltage region,has the great potential as the anode of SIBs with high energy density.
文摘作为电池的重要组成部分,电解质在很大程度上影响着锂电池的安全性、温度适应性、充放电性能和循环寿命。研究合成了二氟草酸硼酸锂(LiODFB)-N-甲基-N-甲氧基乙基吡咯烷双(三氟磺酰亚胺)(Pyr1,2O1TFSI)/亚硫酸酯电解质,展现出良好的离子传导性、电极相容性和宽工作温度范围,其中LiODFB-Pyr1,2 O 1TFSI/DMS电解质体系的电导率和锂离子迁移数分别为8.163×10^(-3)S·cm^(-1),0.28。首次将离子液体基电解质体系的应用温度范围拓展到-40℃,使Li/MCMB电池和Li/LiFePO_4电池在-40~60℃的工作温度范围内均表现出理想的电化学性能。以Li[N(SO_2CF_3)_2](LiTFSI)作为锂盐,将三(乙二醇)二甲醚(TEGDME)作为共溶剂,结合离子液体Pyr1,2O 1TFSI,制备系列Li/S电池电解质。含Li TFSI-(70 wt%)Pyr1,2 O 1TFSI/(30 wt%)TEGDME电解质的Li/S电池表现出优秀的循环性能和倍率性能,在0.1 C充放电倍率下,首周循环周期放电比容量1 212.8 m Ah·g^(-1),循环100周后仍然维持在693.5 m Ah·g^(-1)。在1 C放电倍率下,循环100周放电比容量约为827.3m Ah·g^(-1),库伦效率达到99%以上。同时,该电解质还具有良好的高温性能,电池在80℃仍然可以正常工作,放电容量达1 005.3 m Ah·g^(-1)。在总结相关研究工作的基础上,从离子液体/有机共溶剂电解质体系出发,首次半定量对离子液体/共溶剂体系和电化学基本性质间的构效关系进行了深入分析,对未来面向不同应用方向的锂二次电池电解质体系的设计合成具有一定的理论意义和参考价值。
基金supported by National Natural Science Foundation of China(21905304)Natural Science Foundation of Shandong Province(ZX20210028)the Fundamental Research Funds for the Central Universities(19CX05001A).
文摘In this paper,porous partially fluorinated graphene(PFG)for supercapacitors(SCs)was fabricated by a mild and secure one-pot hydrothermal method utilizing weakly coordinating anion BF_(4)^(-) as the fluorine source.The hydrolysis rate of sodium fluoroborate was adjusted by controlling the reaction temperature and PFG containing semi-ionic C-F bonds was obtained,where the content of semi-ionic C-F bonds in PFG can be easily regulated.The final experimental results show that the incorporation of fluorine not only modulates the electrochemical properties of the material,but also creates abundant pores.When assembled in a symmetric supercapacitor,the PFG shows a high specific capacitance of 269.7 F g^(-1) at 1 A g^(-1) and a superior rate capability with 89.3%capacitance retained,as the current density is increased from 1 A g^(-1)even to 20 A g^(-1).Furthermore,the resultant energy density for PFG is 9.4 Wh kg^(-1) at a power density of 250.0 W kg^(-1)(1 A g^(-1)).All these results confirm that as-prepared partially fluorinated graphene is appropriate for the application in SCs and mass production.
