Development of Carbonbased Materials for Energy Storage Hui-Ming Cheng( 成会明 ) Shenyang National Laboratory for Materials Science Institute of Metal Research, Chinese Academy of Sciences Shenyang, P. R. China cheng@imr.ac.cn; http://carbon.imr.ac.cn
Comparison of EES Devices Charge Storage Modes: Bulk Charge Storage High Energy Density Low Power Density Surface Charge Storage Low Energy Density High Power Density Common Features: Lower Energy Density @ Higher Power Density Y Gogotsi, et al, Nat. Mater. 7:45 2008
General Strategies for Improvement of EES materials Nanostructuring Nano/micro combination Higher energy density Materials combination Higher power density Higher reliability Longer life Lower cost Hybridization Composition optimization Pore structure control Surface modification Configuration design Novel device design Liu C Cheng HM* et al Advanced materials for energy storage Liu C, Cheng HM et al, Advanced materials for energy storage (Review), Adv Mater 22: E28 E62 2010.
Our Objectives Carbon anodematerials for LIBs From interface modification to commercialization Porous carbons for supercapacitors From pore structure design to novel devices Graphene based composite materials for supercapacitors and LIBs From novel graphene to composites
Our Main Work on LIBs SEI & Interface NG/coating anode CNT/NG anode SEI observation (JPCB 2005) Interaction at interface (JPCC 2007) Coating NG with PyC (Carbon 2006) Coating NG with PVC (JPCC 2008) Urchin like nano/micro (Carbon 2006) CNT mixture (Electrochem Acta 2008) Key:SEI control; Conductivity improvement Commercialized in Shenzhen
Novel Structure--- Urchin-like Nano/Micro Hybrid A combination of both nano/micro scale & graphitic /non graphitic structure
Mechanical Mixing CNT/NG Composite as Anode Materials Only 1~2% CNT addition Carbon Black CNTs Volume energy density increase by 10% Electrolyte wettability increase by 30% Cycling performance from 70 90% Improvement of electrode flexibility Cheng HM, Lei W, et al, Chinese Patent 200810230097.X.
Our Main Work on Supercapacitors Ordered Pore Hierarchical Pore New Device Design Ion transport (JPCB 2005) Pore aspect ratio (JPCC 2008) Design concept (Angew Chem 2008) Synthesis (Carbon 2008) Lithium ion supercapacitor (AFM 2008) 8
Design of Hierarchical Pores Macropore: Ion Reservoir Shorten ion transport length Mesopore: Ion Channel Enable fast ion transport Micropore: Ion Accommodation Enable high capacity Graphitic structure: Electron path High electrical conductivity Wang DW, Cheng HM*, et al, Angew. Chem. Int. Ed. 47: 373 2008.
200nm SEM/TEM Images of HPGC
Energy & Power Density of HPGC Supercapacitors CMK 5: W. Xing, et al, Carbon, 44: 216 2006; ALG C:E. Raymundo Piñero et al, Adv. Mater., 18:1877 2006; PVA porous carbon: T. Morishita,Carbon, 44:2360 2006; Small pore ECs: J. Chmiolaet al Science, 313:1760 2006 Wang DW, Cheng HM*, et al, Angew. Chem. Int. Ed. 47, 373 2008. Cited for 86
Our Main Work on Graphene Synthesis LIB Supercapacitors Chemical exfoliation (Carbon 2009) Arc discharge (ACS Nano 2009) Self assembly (AM 2009) Co 3 O 4 /GNS (ACS Nano 2010) Fe 3 O 4 /GNS Li 4 Ti 5 O 12 /GNS PANi/GNS (ACS Nano 2009) RuO 2 /GNS (AFM 2010) 12
Efficient Utilization of 2D Graphene & High Capacity Electrode Materials Oxides or Metals GNS GNS composite Synergistic effect High capacity High density Agglomeration Poor conductivity Big volume change Suppression of agglomeration/restacking Formation and uniform dispersion of NPs Highly conducting and flexible network Large capacity/capacitance Enhanced cycling stability Good rate capability
RuO 2 /GNS Composites for Supercapacitors RuO 2 /GNS composites have much better cycling stability than RuO 2. RuO 2 /GNS composites have much higher energy density than GNS. RuO 2 /GNS composites have much higher energy density than RuO 2 at higher power density. Wu ZS, Cheng HM*, et al., Adv Funct Mater 2010 (in press)
PANi/GNS Flexible Supercapacitor High gravimetric & volumetric capacitance; Excellent cycling stability. Wang DW, Cheng HM*, et al., ACS Nano 3:1745 2009. Cited for 15
Co 3 O 4 /GNS Anode Materials for LIBs Anchoring Wu ZS, Cheng HM*, et al. ACS Nano, 4: 3187 2010.
Graphene-based Composites for Supercapacitors and LIBs Materials for supercapacitors Pure GNS Compared to activated carbons RuO 2 /GNS MnO 2 /GNS PANi/GNS Materials for LIBs Improved capacitance, high rate performance, and cyclability Pure GNS High irreversible capacity LiFePO 4 /GNS Li 4 Ti 5 O 12 /GNS TiO 2 /GNS Co 3 O 4 /GNS Fe 3 O 4 /GNS Improved capacity, high rate performance, and cyclability
Remarks and Prospects R & D of high performance carbon based energy storage materials are important and have a bright future. Optimization of the microstructure, surface structure, pore structure and composition of energy storage materials are expected to improve their energy storage performance. Hierarchical structuring, nano/micro structuring, composite design, etc. are proved to be highly effective. Important synergistic effects between graphene and electrode materials may be particularly promising in the improvement of energy storage performance.