Great Enhancement of Carbon Energy Storage through Narrow Pores and Hydrogen-Containing Functional Groups for Aqueous Zn-Ion Hybrid Supercapacitor

Abstract

The proton transfer mechanism on the carbon cathode surface has been considered as an effective way to boost the electrochemical performance of Zn-ion hybrid supercapacitors (SCs) with both ionic liquid and organic electrolytes. However, cheaper, potentially safer, and more environmental friendly supercapacitor can be achieved by using aqueous electrolyte. Herein, we introduce the proton transfer mechanism into a Zn-ion hybrid supercapacitor with the ZnSO4 aqueous electrolyte and functionalized activated carbon cathode materials (FACs). We reveal both experimentally and theoretically an enhanced performance by controlling the micropores structure and hydrogen-containing functional groups (–OH and –NH functions) of the activated carbon materials. The Zn-ion SCs with FACs exhibit a high capacitance of 435 F g−1 and good stability with 89% capacity retention over 10,000 cycles. Moreover, the proton transfer effect can be further enhanced by introducing extra hydrogen ions in the electrolyte with low pH value. The highest capacitance of 544 F g−1 is obtained at pH = 3. The proton transfer process tends to take place preferentially on the hydroxyl-groups based on the density functional theory (DFT) calculation. The results would help to develop carbon materials for cheaper and safer Zn-ion hybrid SCs with higher energy.

High-Energy-Density Asymmetric Supercapacitor Based on a Durable and Stable Manganese Molybdate Nanostructure Electrode for Energy Storage Systems

“…At this time, more active materials inside the electrode have no time to participate in the redox reaction, so the surface capacitive contribution process is over 50%, which is consistent with many previously reported studies. 54,55 Additionally, the capacitance contribution percentage of the diffusion-controlled process gradually decreases with increasing scan rate. This result indicates that the surfacecontrolled process occupies a dominant part of charge storage at every scan rate, which is beneficial to the integrity, rate performance, and long cycling stability of the electrode nanostructure.…”

Enhanced Surface Area, Graphene Quantum Dots, and Functional Groups for the Simple Acid-Treated Carbon Fiber Electrode of Flexible Fiber-Type Solid-State Supercapacitors without Active Materials

“…Liu et al revealed both experimentally and theoretically an enhanced performance by controlling the hydrogen-containing functional groups (−OH and −NH functions) of the activated carbon materials. The characterization results revealed the hydrogen-containing functional groups are the key factor on the electrochemical property SCs with aqueous electrolytes . On the other hand, the Raman spectra for the CF and the acid-treated CF electrodes were examined, as shown in Figure c.…”

Multidimensional Carbon-Modified NiCo2O4/Ni–Co–S Nanocomposite Electrode Material for High-Energy Asymmetric Supercapacitors

“…In addition, the electrolyte concentration and the test accuracy of the electrochemical workstation will also have impacts, and these problems also exist in the previously reported literature. 64 This novel electrode possesses the following advantages: An ASC device is assembled by pairing the C-NiCo 2 O 4 /C@ Ni−Co−S positive electrode with the AC negative electrode to test the practical application potential of electrode materials. Before the ASC device is assembled, the performance of the activated carbon electrode is tested in the three-electrode test system, as shown in Figure S8.…”