Combustion conversion of wood to N, O co-doped 2D carbon nanosheets for zinc-ion hybrid supercapacitors

Chemistry An Asian Journal

et al. 2021

Zn is a promising anode for aqueous energy storage owing to it intrinsic superior properties such as large capacity, abundant reserves, low potential and safety. But, the growth of dendrites during charge and discharge leads to a decrease in reversibility. In addition, further development of zinc‐ion hybrid capacitors (ZICs) is seriously challenging because of the lack of an exceptional cathode. Herein, we use ZIF‐8 annealed at 500 °C (annealed ZIF‐8) as a host material for stable and dendrite‐free Zn anodes. Utilization of annealed ZIF‐8 results in dendrite‐free Zn deposition and stripping as a result of its porous construction, which contains trace Zn. Furthermore, we firstly proposed innovative N,O dual‐doped carbon which was designed by the derived ZIF‐8 (ZIF‐8 derived C) as cathode for high‐energy and power‐density ZICs. The new ZIC assembled by Zn@annealed ZIF‐8 anode and ZIF‐8 derived C cathode provides a capacity of 135.5 mAh g−1 and an energy density of 108.4 Wh kg−1 with a power density of 800 W kg−1 at 1.0 A g−1. In addition, it shows outstanding cycling stability of 91% capacity retention after 6000 cycles at 5.0 A g−1. Moreover, the solid‐state ZICs can drive LEDs and smart watches. This ZIC holds promise for the practical application of supercapacitors.

Section: Resultsmentioning

confidence: 48%

A ZIF‐8 Host for Dendrite‐Free Zinc Anodes and N,O Dual‐doped Carbon Cathodes for High‐Performance Zinc‐Ion Hybrid Capacitors

Lei

Zheng

Chemistry An Asian Journal

et al. 2021

“…As shown in Figure S9 (Supporting Information), the ZHSC based on the cathode material rGO only possessed 116 F g −1 at 0.5 A g −1 and 57.5% capacitance retention at 5 A g −1 , demonstrating the increased capacitance and better rate performance due to the N/P doping. The ZHSC device based on the cathode material NP-rGO also yielded a high gravimetric energy density of 100.2 Wh kg −1 at a power density of 487.5 W kg −1 based on the active materials, which was better than the other reported ZHSCs, [7,15,18,32] as exhibited in Ragone plot (Figure S10, Supporting Information). Even at a power density of 6400 W kg −1 , the energy density can still reach 26.5 Wh kg −1 , demonstrating the high energy and power advantage of hybrid capacitors.…”

Section: Resultsmentioning

confidence: 93%

Flexible Quasi‐Solid‐State High‐Performance Aqueous Zinc Ion Hybrid Supercapacitor with Water‐in‐Salt Hydrogel Electrolyte and N/P‐Dual Doped Graphene Hydrogel Electrodes

Deng

Wang

Advanced Sustainable Systems

et al. 2021

Carbon-based supercapacitors can be charged and discharged in seconds with a high power density (up to 10 kW kg −1 ) and long cycling life via fast ion adsorption and desorption in Helmholtz double layer at the interface between electrodes and electrolyte. [5] However, their energy density (5-10 Wh kg −1 ) was no better than LIBs. [6] Consequently, the hybrid supercapacitor was assembled by combining the battery-type anode and the capacitor-type cathode to achieve the trade-off between energy density and power density. [7] And more and more research focused on hybrid capacitors, including Li + , [8] Na + , [9] K + , [10] Zn 2+ , [7a] and Al 3+[11] based hybrid supercapacitors. Nevertheless, the use of organic electrolytes will lead to high safety risks and environmental pollution. [12] To explore more environmentally friendly electrolytes, the water-based electrolyte has been paid many efforts, [13] where zinc-ions hybrid supercapacitors (ZHSCs) were especially attractive owing to zinc high specific capacity (5855 mAh cm −3 or 823 mAh g −1 ), the low redox potential of −0.76 V (vs standard hydrogen electrode). [14] Meanwhile, considering the high reactivation of metallic lithium, potassium, and sodium in the atmosphere and aqueous electrolyte, metallic Zn was more suitable for use as electrodes directly in a water-based system. [15] Besides, the construction of water-based devices can avoid high fabrication costs arose from the strict anhydrous and oxygen-free environment for organic electrolytes. Also, Zn and its compounds are abundant and inexpensive in nature. [16] For example, Dong et al. reported the aqueous ZHSC using ZnSO 4 as electrolyte and Zn foil as anode achieved an energy density of 84 Wh kg −1 with a power output of 14.9 kW kg −1 , which was superior to the power density of batteries and the energy density of supercapacitors. [7a] The aqueous ZHSCs inevitably suffer the decomposition of water when a wider voltage window was required ascribed to the competitive hydrogen evolution (<0.2 V vs Zn 2+ /Zn) and oxygen evolution (>1.8 V vs Zn 2+ /Zn) of water molecules. [2d] A wider voltage window can be beneficial to increasing the energy density according to the formula: E = 1/2 CV 2 (1). Fortunately, emerging "water-in-salt" electrolyte can effectively broaden the Aqueous zinc ion hybrid supercapacitors (ZHSCs) have attracted considerable attention owing to the bivalent nature, high abundance, and stability in the water-based system of zinc. High energy density and superb power output can be achieved simultaneously by integrating a battery-type electrode and a capacitive-type electrode. However, there are still many issues that remain, including but not only hydrogen evolution reaction, dendrite growth, and dramatic capacity loss at low temperatures. Herein, a new type of hybrid "water-in-salt" hydrogel electrolyte based on 1 m Zn(CH 3 COO) 2 and 20 m CH 3 COOK to expand the voltage window of ZHSCs to 0-2.1 V by suppressing the decomposition of water molecules is developed. The aqueous ZHSC deliver...

“…An N, O co-doped 2D carbon nanosheet (NOCS) has been prepared by using zinc (NO 3 ) 2 .6H 2 O as an oxidant and urea as a fuel via a one-step combustion conversion method for wood. [53] The as-produced NOCS has a relatively uniform 2D surface structure and a super high SSA (1248 m 2 g À 1 ), which cannot only provide a short electric/ion transmission path plus optimized wettability and conductivity for a high power output but can also offer abundant surface active sites and improve the zinc ion adsorption capacity for high energy storage. Benefiting from these advantages, the as-assembled ZICs with NOCS deliver a high specific capacity (111 mAh g À 1 at 0.1 A g À 1 ), a maximum energy density (109.5 Wh kg À 1 at a power density of 225 kW kg À 1 ) in a voltage range of 0.1-1.7 V and an outstanding capacity retention property (92.7 % capacity retention for 5000 cycles at 5 A g À 1 ).…”

Section: Biomass-derived Carbon Materials For Zicsmentioning

confidence: 99%

Carbon‐Based Materials for a New Type of Zinc‐Ion Capacitor

Gao

et al. 2021

ChemElectroChem

Zinc-ion capacitors (ZICs), as a new type of electrochemical energy storage (EES) device with great development prospects, have garnered considerable attention because they integrate the advantages of high-energy zinc-ion batteries and highpower supercapacitors to meet people's demand for low-cost, long-term durability and high safety. Nevertheless, the investigation of ZICs remains in its infancy, and many problems need to be resolved. In particular, the challenge caused by the finite ion adsorption capacity of carbon-based electrodes gravely limits the energy density of ZICs. Consequently, determining how to design a new type of carbon material with a high energy density without affecting its inherent power and longterm durability has become a key issue. This Review systematically summarizes the research progress in the preparation, morphology, composition, and electrochemical properties of various carbon-based materials used in ZICs in recent years, focusing on the charge-storage mechanism. Current challenges and future opportunities in the application of carbon-based materials in ZICs are also presented. This Review will help researchers understand ZICs further and develop new EES systems to satisfy the needs of quickly expansion electric automobiles and intelligent electronic device.