A hydrogel-mediated scalable strategy toward core-shell polyaniline/poly(acrylic acid)-modified carbon nanotube hybrids as efficient electrodes for supercapacitor applications

Abstract

Structural failure of polyaniline (PANI) stemmed from repeated swelling-shrinkage during Faradic process represents an imminent issue hindering the real application of this material for advanced energy storage. Herein, we explore a clean and facile hydrogel-mediated layer-by-layer strategy to conformally coat a layer of oriented PANI nanofibers on multi-walled carbon nanotubes (MWCNTs) where a layer of UV-polymerized poly(acrylic acid) (PAA) hydrogel is first formed in between as electrodes for supercapacitors. Such an intriguing core-shell tri-component structure perfectly alleviates the drawbacks of PANI as well as combines the advantages of MWCNTs. Especially, the hydrogel used increases the adhesion between PANI and MWCNTs, buffers the structural variation of PANI during cycling, and provide extra driving force accelerating electrolyte penetration throughout active materials. Therefore, the well-intergrown hybrids (PANI/P-MWCNT) display high electrochemical performance as compared to PANI and PANI/MWCNT, i.e., an improved capacitance of 612.5 F g–1 at 0.5 A g–1, and excellent cycling behavior of 81.5% capacitance retention at 5 A g–1 over 1500 cycles. Also, the maximum energy density of the PANI/P-MWCNT based symmetric configuration reaches 8.2 Wh kg–1. Significantly, such a hydrogel-bridged design concept may find the important application for the synthesis of competitive candidates for energy storage.