Improvement of system capacitance via weavable superelastic biscrolled yarn supercapacitors

Abstract

Yarn-based supercapacitors having improved performance are needed for existing and emerging wearable applications. Here, we report weavable carbon nanotube yarn supercapacitors having high performance because of high loadings of rapidly accessible charge storage particles (above 90 wt% MnO2). The yarn electrodes are made by a biscrolling process that traps host MnO2 nanoparticles within the galleries of helically scrolled carbon nanotube sheets, which provide strength and electrical conductivity. Despite the high loading of brittle metal oxide particles, the biscrolled solid-state yarn supercapacitors are flexible and can be made elastically stretchable (up to 30% strain) by over-twisting to produce yarn coiling. The maximum areal capacitance of the yarn electrodes were up to 100 times higher than for previously reported fibres or yarn supercapacitors. Similarly, the energy density of complete, solid-state supercapacitors made from biscrolled yarn electrodes with gel electrolyte coating were significantly higher than for previously reported fibre or yarn supercapacitors.

Weavable asymmetric carbon nanotube yarn supercapacitor for electronic textiles

“…Environmentally friendly, cost-effective, highly performing metal oxides (MnO 2 ) 8,9 or various conducting polymers (e.g., poly(3,4-ethylenedioxythiophene) (PEDOT), polyaniline (PANI), polypyrrole (PPy)) 2,10-14 have been extensively studied as pseudocapacitive additives to dramatically improve the charge storage capability of 1D supercapacitors. Asymmetrically congured 1D supercapacitors used active materials like graphene, carbon nanotubes (CNTs), and PPy for anode yarns and materials like MnO 2 , MoS 2 , Ni(OH) 2 , Co 3 O 4 for cathode yarns, resulting in voltage windows between 1.5 V and 1.8 V. [15][16][17][18][19][20][21][22] In this study, we realized ber supercapacitors having both high specic capacitances and increased potential windows. The rst utilized strategy was to trap pseudocapacitive guest materials within vascular, high electrical conductivity networks of twist-spun CNT yarns, which maximized the weight percent of the guest without signicantly hindering accessibility of the electrolyte to the guest.…”

“…[1][2][3][4][5][6][7] However, the energy storage densities of supercapacitors are lower than for the best batteries. In order to achieve high energy storage density for yarn or ber based supercapacitors, previous research has been conducted in two directions: one is to increase the capacitance (C) of the device by introducing pseudocapacitive materials, while the other is to widen the voltage window (V) of electrochemical operation by using asymmetric electrodes.…”

Carbon nanotubes and manganese oxide hybrid nanostructures as high performance fiber supercapacitors

“…Supplementary Figure 1e shows an SEM image of a crosssectional area at low resolution. Neither the physically overwrapping method 11 nor the "layer-by-layer" method 30 are applicable for depositing MnO 2 nanostructures into the heavily interconnected CNT networks we produced with high electrical conductivity values.…”

“…Redox-active materials, especially inorganic systems such as MnO 2 , RuO 2 , Ni(OH) 2 , and Co(OH) 2 , are highly brittle and exhibit poor electrical conductivity values 27 . In this context, Kim and co-workers 11,28] have recently reported an effective approach that is able to overcome both the brittleness and low electrical conductivity. In particular, manganese oxide (MnO 2 ) nanoparticles were uniformly deposited on a piece of a CNT sheet via drop casting a dispersion containing MnO 2 nanoparticles which was then twisted into bi-scrolled yarns.…”

“…Their wearable nature, low weight, and high flexibility make them suitable for powering portable microelectromechanical devices [4][5][6] or other wearable electronic systems [7][8][9][10][11] . Similar to conventional planar-and cylindrical-shaped supercapacitors, FSCs store energy via either the electrical double layer (EDL) principle or the pseudocapacitance mechanism 1 .…”