Nitrogen-Doped Carbon Derived from Deep Eutectic Solvent as a High-Performance Supercapacitor

Abstract

As a kind of ionic fluid, deep-eutectic solvent (DES) has been used not only as a solvent but also as a precursor for carbon preparation in recent years. Herein, porous nitrogen-doped carbon (NC) has been prepared via simple pyrolysis of l-tyrosine-based DES. The effects of the proportion of the components in DES and the carbonization temperature on the morphology, pore structure, chemical composition, and the performance for supercapacitor application have been investigated. The as-prepared NCs show large surface areas, high nitrogen contents, hierarchical porous structures, and excellent capacitive performances. Specifically, the optimized sample exhibits a higher specific capacitance (306.5 F g–1), better rate capability (70.3% at 50 A g–1), and also shows high area capacitance (7.1 F cm–2) and specific capacitance (235.8 F g–1) when 30 mg/cm2 of the sample is loaded. The constructed symmetric supercapacitor attains a high energy density of 16.9 W h kg–1 (at 450 W kg–1) in the neutral electrolyte and outstanding cycling stability of 100% retention after 50,000 cycles. Moreover, the fabricated symmetrical solid KOH/poly­(vinyl alcohol) supercapacitor displays a superior energy density of 15.2 W h kg–1 at 700 W kg–1 and can retain 8.8 W h kg–1 at 14 kW kg–1. Our work presents a route for the synthesis of porous carbon using DES as the carbonaceous precursor and also demonstrates its possible application in energy storage.

Nitrogen-Doped High Surface Area Porous Carbon Material Derived from Biomass and Ionic Liquid for High-Performance Supercapacitors

“…The intensity of the diffraction peaks at 26.5°and 43.5°decreases with the increasing nitrogen concentration, indicating the more substantial disruption to graphitic structure and the formation of more disordered carbon. 50,51 The degree of doping of ACs was further evaluated by Raman spectroscopy. The Raman spectrum of NAC (3:1), NAC (2:1), NAC (1:1), and AC-800 in Figure 1b shows two distinctive bands at around 1326 cm −1 (D) and 1592 cm −1 (G).…”

Flexible Solid-State Supercapacitors with Outstanding Capacitive Performance Enabled by N/B-Codoped Porous Carbon Nanosheets

“…In addition, meso- and macropores are abundant in the freestanding BNC-850 film due to the pore formation of ice crystals. Undoubtedly, the lamellar stacking of ultrathin nanosheets accompanying the intersheet nanometer- and micrometer-sized voids can not only ensure fast diffusion and migration of electrolyte ions ,, but also facilitate the Faradaic reactions of N-, B-, and O-containing groups, ,, thus enhancing the rate capability and the PSC contribution simultaneously. The PSC contributions in the BNC-750, BNC-850, and BNC-950 electrodes have already been investigated by kinetic analysis and were estimated to be 34.1, 30.1, and 25.3% (Figure d), respectively.…”

“…For example, the N/B/O contents of BNC-750, BNC-850, and BNC-950 nanosheets were found to be 10.1/4.2/11.3, 9.6/3.9/10.4, and 4.5/3.4/8.9 atom %, respectively, in which the N-containing (pyridinic-N, C–N–B, and pyridine-N-oxide), B-containing (B–N), and O-containing (C–O, O–CO) functionalities that can participate in the Faradaic reactions account for 71.2/63.8/75.1, 72.7/55.8/77.8, and 58.9/34.5/58.9%, respectively. Among these N-, B- and O-containing functionalities, pyridinic-N can significantly enhance the capacitance because of the faradaic reactions, while graphitic-N can improve the electrical conductivity. , O-containing groups such as O–CO, C–O–B, and C–O are capable of greatly enhancing the wettability of BNC- x electrodes. , O-doping coupled with graphitic-N can remarkably improve the rate capability of BNC- x electrodes. In addition, B-doping in carbon (especially C–B–N) can enhance the cycling stability; moreover, BC 2 O and BCO 2 species can improve the accessibility of electrolyte ions through the electrostatic and ion−π interactions. , The synergistic effects of N/B/O-codoping endow the BNC- x film electrodes with high capacitance, high rate capability, and long cycle-life (vide infra).…”

Non‐Flammable Sodium Asymmetric Imide Salt‐Based Deep Eutectic Solvent for Supercapacitor Applications

“…Taking into account the oxidative and reductive stability of electrolytes, a great deal of research on new formulations has been conducted, giving rise to ionic liquids (ILs) and deep eutectic solvents (DES) as suitable candidates for SC applications. [2][3][4][5][6] DESs' low cost, wide electrochemical stability window, and simplicity of formulation render them attractive in energy devices. Their most appealing feature, however, is their superionic character, which gives them transport properties (e. g., conductivity and viscosity) that are strikingly improved at elevated temperatures.…”

“…And arguably so, as the energy of the EDLC is analogous to the square root of the SC voltage (see Equation 2 below). Taking into account the oxidative and reductive stability of electrolytes, a great deal of research on new formulations has been conducted, giving rise to ionic liquids (ILs) and deep eutectic solvents (DES) as suitable candidates for SC applications [2–6] . DESs′ low cost, wide electrochemical stability window, and simplicity of formulation render them attractive in energy devices.…”