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Title: Particle size effect in porous film electrodes of ligand-modified graphene for enhanced supercapacitor performance

Graphene-based electrodes for high performance supercapacitors are developed by taking advantage of particle size control, large mass loading, and surface functionalization of reduced graphene oxide (rGO) sheets. Two controlled sizes of graphene sheets (100 nm vs. 45 μm average lateral dimensions) were prepared to study two-electrode system performance. The nano-size graphenes led to the formation of mesoporous films, resulting in higher capacitance, better capacitance retension and lower equivalent series resistance (ESR), indicating better surface usability for diffusion and accessibility of electrolyte ions by shortening transport paths (compared with horizontally stacked films from micro-sized graphenes). For studies using an aqueous electrolyte, the maximum specific capacitance of nano-rGO film was 302 F/g (at 1 A/g with 4.3 mg/cm 2 of mass loading), which was ~2.4 times higher than micro-rGO film, and achieved a ~67% reduced ESR. With an organic electrolyte, the nano-rGO delivered ~4.2 times higher capacitance (115 F/g at 2 A/g with 4.3 mg/cm 2), 4.0 times lower IR drops, and an order-of-magnitude lower charge-transfer resistance with an energy density of 18.7 Wh/kg. Finally, the results of this work indicate that the size control of graphene sheet particles for film deposit electrodes can be a simple but effective approach to improvemore » supercapacitor performance.« less
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [1] ;  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Georgia Inst. of Technology, Atlanta, GA (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; # DE-AR0000303
Type:
Accepted Manuscript
Journal Name:
Carbon
Additional Journal Information:
Journal Volume: 119; Journal Issue: C; Journal ID: ISSN 0008-6223
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Temperature Materials Lab. (HTML)
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY; 36 MATERIALS SCIENCE; nano sized graphene; graphene functionalization; reduced graphene oxide; supercapacitor
OSTI Identifier:
1366396
Alternate Identifier(s):
OSTI ID: 1396917