Construction of Direct-Growth in Situ Doped Polypyrrole/CNT Core Shell Composite on Carbon Cloth As a High Performance Flexible Supercapacitor

In the 21st century, the growing demand of the smart portable electronic gadgets, such as roll-up display, electric paper and wearable systems for smart electronics need to develop the flexible super capacitor with both high-power density and large energy density. Conducting polymers (CPs) are one of the most potential pseudo-capacitor materials for foundation of flexible-supercapacitors, motivating the existing energy storage devices towards the future advanced flexible electronic applications due to their high redox active specific capacitance and inherent elastic polymeric nature [1,2]. To the best of our knowledge, among CPs, polypyrrole (PPy) have shown better elasticity and conductivity than the polyaniline. However, a key weakness of the PPy based supercapacitor electrode is mechanical instability due to the considerable volume change during the repeated charge-discharge process. Consecutively binary composites of PPy with CNTs on flexible substrate have been explored on the traditional slurry process. A major limitation of the traditional slurry derived electrode consists in the sluggish rate of ion transport during the faradic reactions in electrode due to the high internal resistance of binders. To solve this problem in this work, polypyrrole/CNT core shell composite directly grown on flexible carbon cloth (CC). The CNTs were directly grown on the CC by microwave plasma-enhanced chemical vapor deposition in order to obtain a strong adhesion of CNT on CC, and then the in situ doped well uniform PPy/CNT core-shell composite was synthesized via oxidative electropolymerisation. The PPy/CNT/CC electrode fabricated by direct growth process with optimum thickness of PPy possesses the low interfacial resistance, and shows high gravimetric capacitance of 486.1 F/g with a mass loading around 6 mg/cm² at a current density of 0.9 A/g. Furthermore, this PPy/CNT/CC electrode delivers remarkably a very high cycle stability (17% capacitance loss after 10000 cycles) and high flexibility.  The detail core shell electrode fabrication process of PPy/CNT on flexible CC and their electrochemical pseudo-capacitance with stability performance will be discussed. These results clearly present a cost-effective and simple fabrication method of the PPy/CNT composite with enormous potential in flexible energy storage device applications.

 

References

[1]    Y.Y. Horng, Y.C. Lu, Y.K. Hsu, C.C. Chen, L.C. Chen, K.H. Chen, Journal of Power Sources. , 2010, 195, 4418.

[2]    I. Shown, A. Ganguly, L. C. Chen, K. H. Chen, Energy Science & Engineering, 2014, DOI: 10.1002/ese3.50.