Lighter, Faster and Smaller Dense Graphene Assemblies: Remedy for Compact Energy Storage. Outline

Transcription

1 The 8 th GO Symposium, Kumamoto Univ., 30 June 2017 Nanocarbon realizes Low carbon! Lighter, Faster and Smaller Dense Graphene Assemblies: Remedy for Compact Energy Storage Quan-Hong Yang ( 楊全红 ) Tianjin University qhyangcn@tju.edu.cn Outline ² W hy high volumetric performance (being smaller) for Energy Storage (EES) ² Self-assembly of graphene oxide (GO) at interface: New Strategy for producing functional carbons ² Building carbon electrodes with high volumetric performance (Supercapacitor as an example) Methodology, Materials, Electrodes and Devices ² Concluding Remarks

2 Requirements of EES devices As compact as possible The biggest concern for real application: how much energy stored in a limited space Gravimetric and volumetric performances: equally important! For materials: as dense as possible materials For electrode: as large fraction as possible active materials in a device cell; as thick as possible!!! Gogotsi, Simon, Science 2011, 334, 917 Yang, et al. Energy Environ Sci 2016, 9, 3135 Outline ² W hy high volumetric performance (smaller) for Energy Storage (EES) ² Self-assembly of graphene oxide (GO) at interface: New Strategy for producing functional carbons ² Building carbon electrodes with high volumetric performance for Supercapacitors: Methodology, Materials, Electrodes and Devices ² Concluding Remarks

3 Magic at interface: Self-assembly of GO Water dispersible graphene oxide (GO) GO is an amphiphilic and 2D soft material Concentrating and self-assembly at liquid-air, liquid-liquid, liquid-solid interface Ideal building block for Carbon solids Also see pioneering works from Jiaxing Huang, Dan Li and other groups Adv Mater 2014, 26, 5586 GO assembly: a unique method for producing carbon materials ØEffectiveness to produce functional carbon materials The very point is hydrogel filled with water: Controlled removal of the contained liquid (water) results in well-controlled texture in functional carbons ØMany uniqueness, merits AdvFunctMater 2014, 24: 3456 Energy Storage Materials Packing Density Ion Channel Electron Network

4 a b 5n m Outline ² W hy high volumetric performance for Energy Storage ² Self-assembly of graphene oxide at interface: New Strategy for producing functional carbons ² Building carbon electrodes with high volumetric performance (Supercapacitor as an example): Methodology, Materials, Electrodes and Devices ² Concluding Remarks Strategy Ways to assemble carbon structures 5nm c Highly dense d yet Nonporous Porous yet low density Graphene building block to balance density and porosity in carbon? Energy Environ Sci 2015, 334, 917; Energy Storage Mater 2016, 2, 107

5 Methodology Freeze drying vs Capillary evaporation Controlling water removal Freeze drying Capillary evaporation Fine control of carbon texture Carbon foam Li, et al. Nat. Commun Qu, et al. Angew Chem 2011 Gao, et al. Adv. Mater Qiu, et al. Adv. Mater Carbon solid Robust but elastic network Different interactions between carbon sheets and water (water or ice) Capillary evaporation: Capillary force induced shrinkage of pre-formed stable carbon network in self-assembled hydrogel) Sci Rep 2013, 3: 2975 Materials High density (Hard pill) vs. Low density (foam) (a) Carbon foam (b) Carbon solid Tao, Yang*, et al. Carbon 2014, 69, 169 Up to 70% density of graphite( m 2 /g) Sci Rep 2013, 3: 2975

6 High density but porous structure (002) Typical for layered carbons XRD 1 Graphite 50 HPGM HPGM 10 Pencil Not layered structure Interlinked sheets circle-like pores Sci Rep 2013, 3: 2975 Recorded for carbon-only electrode (376 F/cm 3 ) Acceptable conductivity free of any heating (16 S/m) Energy density Aqueous system:13.1 Wh/L (39.5 W/L), Organic system: 37.1 Wh/L (98.8 W/L) p Ideal capacitive behavior p Good rate capability p Ragone plots Sci Rep 2013, 3: 2975

7 ISSN PAPER Jiayan Luo, Quan-Hong Yang et al. Ultra-thickgraphene bulk supercapacitor electrodes for compact energy storage Volume 9 Number 10 October 2016 Pages Electrode: Dense packing of pseudocapacitive materials into graphene network Design principle of carbon-based electrodes for high volumetric performance Leaving fast ion channel and electrode network RuO2 Leaving ion channel 1415 F/cm 3 PANI Ion and electron bi-conductor 1100 F/cm 3 Adv Mater 2015, 27, 8082; Nano Energy 2017, 36, 349; Small 2017 Device: Ultra-thick graphene bulk electrodes (400 μm) Materials design from a device perspective Basic design principle for a real EES device: balanced specific capacitance, electrode density, electrode thickness and operation voltage Ionic liquid ZnCl : sacrificing pore former 2 Ø 370~over 1100 m 2 g -1 Ø g cm -3. Energy & Environmental Science 65 Wh /L Energy Environ Sci 2016, 9, 3135

8 Summary and Perspectives Graphene should do what conventional carbons cannot do well or cannot do ØBridging carbons and graphene: Compact assembly of graphene: Solution for practical use of nanocarbons in EES devices Strategy (EES 2015), Methodology (Adv Mater 2009, Adv Mater 2014), Materials (Sci Rep 2013), Electrodes (Adv Mater 2015, Nanoscale 2015, Nano Energy 2017, Small 2017, Adv Mater 2017) and Devices (EES 2016) Strategy for Devices Acknowledgements Financial support NSFC, MOST, MOE, Tianjin, Shenzhen Collaborators Prof. F.Y. Kang (Tsinghua) & his team Prof. H.-M. Cheng (IMR CAS,&TBSI, Tsinghua) &his team Prof. T. Kyotani (Tohoku) & his team Prof. J. X. Huang (Northwestern) Prof. J. Y. Luo (TJU) Students Assembly W. Lv, C. M. Chen, J. J. Shao, Y. Tao, C. Zhang Supercapacitor W. Lv, Y. Tao, H. Li, Y. Xu, X. Xie, H. Ma, D. Kong