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Interconnecting Carbon Fibers with the In-situ Electrochemically Exfoliated Graphene as Advanced Binder-free Electrode Materials for Flexible Supercapacitor.

Zou Y, Wang S - Sci Rep (2015)

Bottom Line: The low surface area of CC and the presence of big gaps (ca. micro-size) between individual CFs lead to poor performance.The in-situ electrochemical intercalation technique ensures the low contact resistance between electrode (graphene) and current collector (carbon cloth) with enhanced conductivity.The as-prepared electrode materials show significantly improved performance for flexible supercapacitors.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China [2] School of Chemistry, The University of Manchester, Oxford Road, Greater Manchester, M13 9PL, United Kingdom.

ABSTRACT
Flexible energy storage devices are highly demanded for various applications. Carbon cloth (CC) woven by carbon fibers (CFs) is typically used as electrode or current collector for flexible devices. The low surface area of CC and the presence of big gaps (ca. micro-size) between individual CFs lead to poor performance. Herein, we interconnect individual CFs through the in-situ exfoliated graphene with high surface area by the electrochemical intercalation method. The interconnected CFs are used as both current collector and electrode materials for flexible supercapacitors, in which the in-situ exfoliated graphene act as active materials and conductive "binders". The in-situ electrochemical intercalation technique ensures the low contact resistance between electrode (graphene) and current collector (carbon cloth) with enhanced conductivity. The as-prepared electrode materials show significantly improved performance for flexible supercapacitors.

No MeSH data available.


Cyclic voltammetry at the scan rate of 10 mV/s (A) and charge/discharge at the current load of 3 mA (B) curves of flexible supercapacitors based on the CC and Ex-CC electrode materials with 1 M H2SO4 as the electrolyte.
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f4: Cyclic voltammetry at the scan rate of 10 mV/s (A) and charge/discharge at the current load of 3 mA (B) curves of flexible supercapacitors based on the CC and Ex-CC electrode materials with 1 M H2SO4 as the electrolyte.

Mentions: Based on the above physical and chemical characterizations, it is expected that Ex-CC would have attractive electrochemical performance in supercapacitors. Since the Ex-CC with high surface area originates from CC and preserves the well-defined cloth structure with good mechanical strength, Ex-CC could be an excellent candidate as an advanced binder-free electrode for flexible supercapacitors. The symmetric flexible supercapacitors were constructed using two Ex-CC samples as both positive and negative electrodes, Whatman filter membrane as the separator, and 1.0 M H2SO4 solution as the electrolyte. For comparison, pristine CCs were also assembled to a symmetric flexible supercapacitor. The area of the devices is 2 × 2 cm2. CV measurements were first carried out to observe the electrochemical behaviour of Ex-CC and CC-based flexible supercapacitors. Figure 4A shows the CV curves of the two flexible supercapacitors using Ex-CC and CC as electrodes, from which the remarkable difference in the electrochemical behaviour and properties between the two electrodes could be easily recognized. The CV curve at the Ex-CC electrode is close to the ideal rectangular shape, indicating smaller internal resistance in the electrode, while CC shows a very poor rectangular shape. Although carbon fiber is a highly conductive substrate, carbon fibers in CC have poor affinity with electrolytes due to the inert surface. After the electrochemical cation intercalation, graphite in the fibers expanded to graphene with more edge defects exposed, which may increase the affinity with electrolyte through the capillary interaction. Thus, Ex-CC is more electrochemically affinitive toward electrolyte. On the other hand, for Ex-CC, the interconnecting of carbon fibers by the in-situ exfoliated graphene would enhance the conductivity of the composites for use as electrode materials. From the CV curves, it could be observed that Ex-CC showed much higher current than CC, which could be attributed to the unique structure of the interconnected carbon fibers through the in-situ exfoliated graphene.


Interconnecting Carbon Fibers with the In-situ Electrochemically Exfoliated Graphene as Advanced Binder-free Electrode Materials for Flexible Supercapacitor.

Zou Y, Wang S - Sci Rep (2015)

Cyclic voltammetry at the scan rate of 10 mV/s (A) and charge/discharge at the current load of 3 mA (B) curves of flexible supercapacitors based on the CC and Ex-CC electrode materials with 1 M H2SO4 as the electrolyte.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493559&req=5

f4: Cyclic voltammetry at the scan rate of 10 mV/s (A) and charge/discharge at the current load of 3 mA (B) curves of flexible supercapacitors based on the CC and Ex-CC electrode materials with 1 M H2SO4 as the electrolyte.
Mentions: Based on the above physical and chemical characterizations, it is expected that Ex-CC would have attractive electrochemical performance in supercapacitors. Since the Ex-CC with high surface area originates from CC and preserves the well-defined cloth structure with good mechanical strength, Ex-CC could be an excellent candidate as an advanced binder-free electrode for flexible supercapacitors. The symmetric flexible supercapacitors were constructed using two Ex-CC samples as both positive and negative electrodes, Whatman filter membrane as the separator, and 1.0 M H2SO4 solution as the electrolyte. For comparison, pristine CCs were also assembled to a symmetric flexible supercapacitor. The area of the devices is 2 × 2 cm2. CV measurements were first carried out to observe the electrochemical behaviour of Ex-CC and CC-based flexible supercapacitors. Figure 4A shows the CV curves of the two flexible supercapacitors using Ex-CC and CC as electrodes, from which the remarkable difference in the electrochemical behaviour and properties between the two electrodes could be easily recognized. The CV curve at the Ex-CC electrode is close to the ideal rectangular shape, indicating smaller internal resistance in the electrode, while CC shows a very poor rectangular shape. Although carbon fiber is a highly conductive substrate, carbon fibers in CC have poor affinity with electrolytes due to the inert surface. After the electrochemical cation intercalation, graphite in the fibers expanded to graphene with more edge defects exposed, which may increase the affinity with electrolyte through the capillary interaction. Thus, Ex-CC is more electrochemically affinitive toward electrolyte. On the other hand, for Ex-CC, the interconnecting of carbon fibers by the in-situ exfoliated graphene would enhance the conductivity of the composites for use as electrode materials. From the CV curves, it could be observed that Ex-CC showed much higher current than CC, which could be attributed to the unique structure of the interconnected carbon fibers through the in-situ exfoliated graphene.

Bottom Line: The low surface area of CC and the presence of big gaps (ca. micro-size) between individual CFs lead to poor performance.The in-situ electrochemical intercalation technique ensures the low contact resistance between electrode (graphene) and current collector (carbon cloth) with enhanced conductivity.The as-prepared electrode materials show significantly improved performance for flexible supercapacitors.

View Article: PubMed Central - PubMed

Affiliation: 1] State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, P. R. China [2] School of Chemistry, The University of Manchester, Oxford Road, Greater Manchester, M13 9PL, United Kingdom.

ABSTRACT
Flexible energy storage devices are highly demanded for various applications. Carbon cloth (CC) woven by carbon fibers (CFs) is typically used as electrode or current collector for flexible devices. The low surface area of CC and the presence of big gaps (ca. micro-size) between individual CFs lead to poor performance. Herein, we interconnect individual CFs through the in-situ exfoliated graphene with high surface area by the electrochemical intercalation method. The interconnected CFs are used as both current collector and electrode materials for flexible supercapacitors, in which the in-situ exfoliated graphene act as active materials and conductive "binders". The in-situ electrochemical intercalation technique ensures the low contact resistance between electrode (graphene) and current collector (carbon cloth) with enhanced conductivity. The as-prepared electrode materials show significantly improved performance for flexible supercapacitors.

No MeSH data available.