A 2.6 V Flexible Supercapacitor Based on Al-MnO₂-Na₂SO₄//AC-KOH with High Specific Energy

Abstract

In this work, we have synthesized Al-doped MnO2 nanoparticles (Al-MnO2) by rapid coprecipitation followed by hydrothermal and heat treatment. Al-MnO2 shows a specific capacitance of 301.8 F g–1 at 1 A g–1 in a sample of 14% Al-MnO2-260 °C. The specific capacitance still remains at 206 F g–1 at 20 A g–1. It also shows a good cycling stability with no capacitance degradation after 5000 cycles. More importantly, a new type of supercapacitor, Al-MnO2|PVA-Na2SO4//PVA-KOH|AC, has been designed using a Na2SO4-poly­(vinyl alcohol)//cation exchange membrane//KOH-poly­(vinyl alcohol)-based decoupled electrolyte. This device exhibits a specific capacitance of 68.9 F g–1 at 1 A g–1, corresponding to 64.7 Wh kg–1 at 1300 W kg–1. It also delivers a good capacitance retention of ∼84% after 5000 cycles. The cell voltage is up to 2.6 V, which could light up a green light-emitting diode. The PVA-based decoupled gel electrolyte offers good processability to assemble flexible and foldable devices, which is important for mass production in manufacturing. These results clearly indicate that such high-voltage flexible supercapacitors with high specific energy are very promising in future wearable electronics.

Cation-doped sea-urchin-like MnO2 for electrocatalytic overall water splitting

“…Observing the entire XRD pattern, it can be seen that the doping of Al 3+ /Fe 3+ expands the lattice spacing of MnO 2 without altering its crystal structure. 36,43,44 According to formulas 3–6, the average grain size ( D ), dislocation density ( δ ), microstrain ( ε ), and stacking fault probability ( α ) of all materials were calculated using the experimental XRD data. 45 The structural parameters of MnO 2 , Al-MnO 2 , and Fe-MnO 2 are shown in Table 1.where θ is Bragg's angle of a particular diffraction peak and λ represents the wavelength of Cu Kα radiation (0.15406 nm).…”

Gels in Motion: Recent Advancements in Energy Applications

“…As far as the application of gel polymers as electrolytes in supercapacitors is concerned, there are several advantages over other classes of electrolytes [45]. With the rapid growth in portable electronic devices, there is an urgent need to develop wearable, flexible energy storage devices like flexible supercapacitors (FSCs) [46][47][48][49][50]. To achieve high performances out of supercapacitors, the development of better electrodes, housing, separators, and other flexible components are crucial; however, this section is dedicated to the development of gel electrolytes to enhance the electrochemical performances of supercapacitors.…”

Development of plasma technology for the preparation and modification of energy storage materials

“…Extensive research has demonstrated the enhanced intrinsic properties of energy storage materials through the introduction of heteroatom doping or functional group modification. This is commonly achieved through various methodologies, including high temperature sintering, 1,2 co-precipitation, 3,4 hydrothermal reactions, 5–7 vapor deposition (CVD/PVD), 8,9 chemical reactions, and other similar approaches. These techniques lead to improvements in specific capacity, initial efficiency, and rate capability of energy storage materials by inducing the formation of defects, vacancies, active sites, 10 etc.…”