Wide Voltage Aqueous Asymmetric Supercapacitors: Advances, Strategies, and Challenges

Abstract

Asymmetric supercapacitors (ASCs) can substantially broaden their working voltage range, benefiting from the advantages of both cathode and anode while breaking through the energy storage limitations of corresponding symmetric cells. Wide voltage aqueous ASCs hold great promise for future electronic systems that require satisfied energy density, power density, and cycle life, due to the advantages of aqueous electrolyte in terms of low cost, operational safety, facile manufacture, environment-friendly, and high ionic conductivity. This review will first briefly present an overview of the historical developments, charge storage mechanisms, and matching principles of wide voltage aqueous ASCs. Then, the cathode and anode materials with wide potential windows for building wide voltage aqueous ASCs over the last few decades are summarized. The next section details the optimization methods of aqueous electrolyte related to wide voltage aqueous ASCs. In addition, the basic device configurations of wide voltage aqueous ASCs are classified and discussed. Furthermore, several strategies are proposed for achieving highperformance wide voltage aqueous ASCs in terms of voltage window, specific capacitance, rate performance, and electrochemical stability. Finally, to motivate further research and development, several key scientific challenges and the perspectives are discussed.

An ultrahigh‐energy density and wide potential window aqueous electrolyte supercapacitor built by polypyrrole/aniline 2‐sulfonic acid modified carbon felt electrode

“…However, the hydrated radius of the sulfonyl groups in the structure of ASA was larger than the H + ions. Therefore, the coulombic efficiency may seem relatively low in Figure 8C 95 . However, a double layer capacitance resulting from the deposition of H + on the surface of the electrodes contributed to the existing pseudo‐capacitance, increasing the specific capacitance value 96‐98 …”

“…Therefore, the coulombic efficiency may seem relatively low in Figure 8C. 95 However, a double layer capacitance resulting from the deposition of H + on the surface of the electrodes contributed to the existing pseudo-capacitance, increasing the specific capacitance value. [96][97][98] The transmission electron image (TEM) and scanning electron microscope (SEM) images of PPy/ASA were taken after cyclic charge-discharge (5000 cycles) were shown in Figure 10.…”

Hydrothermal Synthesis of Flexible Fe‐Doped Polyaniline/Dye‐Functionalized Carbon Felt Electrode for Supercapacitor Applications

“…The construction of high operating voltage electrodes with high surface area, porous structure, and Faradaic active sites is the main goal of high-performance supercapacitor. [67] It is important to select supercapacitor electrode materials and current collectors with a high potential window that can delay for the high oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) events, respectively, in an aqueous electrolyte. It has been stated that carbonbased materials used as current collectors such as carbonbased materials which exhibit corrosion resistance, voltage resistance and superior mechanical strength, increase the longlife cycling and operating voltage of supercapacitor.…”

Sodium Pre-Intercalation Based Na3-Δ-Mno2@Cc for High Performance Aqueous Asymmetric Super Capacitor: Joint Experimental and Dft Study

“…This results in improved cell voltage and energy density of the material. However, the maximum cell voltage obtained so far lies in between 1.4-2.0 V, which is still not enough to practically fulfill the energy demands 3,4 . Therefore, the quest of developing asymmetric super capacitors with voltage range higher than 2.0 V is still an untangled issue 5 .…”