A Flexible Asymmetric NaFePO₄/Carbon Cloth Supercapacitor Using Crosslinked Polyacrylate Gel as Electrolyte

Abstract

With the development of light-weight and bendable electric devices, nowdays, solid-state supercapacitive devices have attracted great attention, in which the classic polymeric electrolytes such as polyvinyl alcohol and polyethylene oxide copolymers are generally used. However, the microphase separation in these polymers and low conductivity affect the ions transfer and the energy-storage performance. In this work, a crosslinked sodium polyacrylate gel (NaPA) is synthesized to replace conventional polymeric electrolyte. Because NaPA is a kind of polymeric salt which has high native degree of ionization in water, the NaPA gel shows low resistance to ion transportation. By using NaPA gel as the electrolyte and carbon cloth as current collector, a flexible solid asymmetric super-capacitor assembled by positive NaFePO 4 /carbon cloth and negative activated carbon/carbon cloth electrode shows the maximum capacitance of 46.33 mF cm À 2 at 1 mA cm À 2 , with a high stability of 87.33 % retention during 5000 charge and discharge cycles. Moreover, this flexible asymmetric supercapacitors showed nearly unchanged capacitance under different bending angles. It is found that the Na + diffusion coefficient in NaFePO 4 /CC//NaPA supercapacitor is 8.05 × 10 À 14 cm 2 ⋅ s, remarkable higher than CC//NaPA and NaFePO 4 / CC//PVA. The high diffusion coefficient and low resistance of NaPA lead to excellent capacitave performance of NaFePO 4 / CC//NaPA, delivering a good application prospect.

Fe‐Alloyed MoNi Nanohybrids as Oxygen Evolution Reaction/Oxygen Reduction Reaction Bifunctional Electrocatalyst for Rechargeable Zinc–Air Batteries

“…[ 42 ] The angle between the curve in the intermediate frequency region and the real axis is the characteristic of ions diffusion to the electrode. [ 43 ] Therefore, according to the semicircle diameter (MoNiFe < MoNi) in the high frequency region of Figure 5d, the electrochemical resistance of MoNiFe nanohybrids is smaller than that of MoNi, due to the enhancement of the electrical conductivity [ 44 ] resulted from the further alloying of Fe element in the MoNi catalyst. As can be seen from the straight line in the low‐frequency region, the slope of MoNiFe is much higher than that of MoNi, indicating that the ion diffusion impedance in the electrolyte is greatly decreased by alloying with Fe.…”

Effects of plasma on electrochemical performance of carbon cloth-based supercapacitor

“…Its contact area with the electrolyte is limited. Therefore, carbon cloth-based supercapacitors [12] only store a small number of charges and have a small electric capacity. In order to improve the electric capacity of carbon cloth-based supercapacitors, it is necessary to improve the wettability between carbon cloth electrode and electrolyte.…”