Deep Eutectic Solvent‐Induced Polyacrylonitrile‐Derived Hierarchical Porous Carbon for Zinc‐Ion Hybrid Supercapacitors

Abstract

Hierarchical porous carbon that possesses large surface area and high porosity has become an important electrode material for supercapacitors. However, some unavoidable issues like complex approach and environmental pollution involved in traditional chemical activation restrict the sustainable development of carbons. Herein, a green, low‐cost, and safe urea‐zinc chloride deep eutectic solvent (DES) is proposed to prepare polyacrylonitrile derived three‐dimensional carbon nanosphere (D‐PC). Specially, the D‐PC efficiently accelerates electrolyte ions migration and enhances charge storage due to its interconnected ionic pathways and large accessible active surfaces. When employing the D‐PC as positive electrode of zinc‐ion hybrid supercapacitors, a high specific capacitance of 261.5 F g−1 at 0.2 A g−1 along with a cycling stability of 91.3 % after 10000 cycles at 5 A g−1. Meanwhile, such device holds the maximum energy/power density of 93.9 Wh kg−1/16.7 kW kg−1 at 0.2 A g−1/20 A g−1, respectively. Thanks to the unique physicochemical properties of as‐obtained D‐PC, an ultrahigh areal capacitance of 2.2 F cm−2 also can be achieved at a mass loading of 23 mg cm−2. The satisfying structure and performance highlight the potential of DESs in the design of functional carbons.

Thermally Chargeable Ammonium‐Ion Capacitor for Energy Storage and Low‐Grade Heat Harvesting

“…It is worth mentioning that the Coulomb efficiency of the electrode can remain a high value over 98 %, indicating a high reversibility. To further study the kinetic behavior of the electrode material, we fitted the relationship between peak current ( i p ) and scan rate ( v ), according to Equations (2) and 3: [35,36] …”

“…The fitted slopes of the right oxidation peaks for the PI and rGO‐PI electrodes were 0.872 and 0.887, respectively (Figure 3g), indicating that both PI and rGO‐PI are dominated by capacitive behavior. Moreover, the electrochemical surface reaction current ( k 1 v ) and diffusion‐controlled current ( k 2 v 1/2 ) contributions are further analyzed by analyzing the CV curves according to the following equations: [36,37] …”

Synergistically Enabling Fast‐Cycling and High‐Yield Atmospheric Water Harvesting with Plasma‐Treated Magnetic Flower‐Like Porous Carbons

“…To synthesize P‐MFPC, the pristine MFPCs were firstly synthesized by dispersing a controlled amount of ZIF‐67 MOF crystals (Figure S1 , Supporting Information) into a PAN suspension (20 wt%) in urea‐ZnCl 2 (molar ratio 7:1) DES, followed by a carbonization process (detailed in the experimental section of Supporting Information) based on the previously reported method. [ 29 ] DECs, consisting of coordinated hydrogen bond donors and acceptors, represent a new type of ionic liquids and have been widely employed in diverse areas due to their low cost, environmental benign, and biodegradability. [ 30 ] Since the urea‐ZnCl 2 DES could form continuous hydrogen networks with PAN and result in a highly porous PAN‐derived carbon doped with abundant oxygen that facilitated water adsorption, [ 29 ] PAN was utilized as the major carbonaceous precursor of MFPCs.…”

A flexible and stable zinc-ion hybrid capacitor with polysaccharide-reinforced cross-linked hydrogel electrolyte and binder-free carbon cathode

“…3g, the oxygen species of GCNF can be evidenced to be C]O (O-I, 531.5 eV), C-O-C/C-OH (O-II, 532.6 eV), and COOH (O-III, 533.7 eV), respectively. 43 In addition, three nitrogenous groups of graphitic or quaternary N (N-Q, 401.0 eV), pyrrolic N (N-5, 399.9 eV), and pyridine N (N-6, 398.5 eV) exist in GCNF (Fig. 3h), where the N-Q benets fast electron transfer to boost the conductivity of carbon materials, and the N-5/N-6 can supply additional Zn 2+ chemisorption sites and promote the hydrophilicity of carbon materials.…”