MXene‐Reduced Graphene Oxide Aerogel for Aqueous Zinc‐Ion Hybrid Supercapacitor with Ultralong Cycle Life

Abstract

is much smaller for medium-and largeenergy storage systems. [9][10][11] Fortunately, constructing hybrid SCs (HSCs) that combine the merits of battery and SC with battery-type electrodes and capacitor-type electrodes is an intelligent way to improve the energy density of SCs. [12] The Li-ion and Na-ion-based HSCs that attempted to further improve the energy density of SCs have made certain progress, but these HSCs generally adopted organic electrolyte, which leads to serious safety issues. [13][14][15][16] Although Li-ion and Na-ion-based HSCs that adopted aqueous electrolyte were seldom reported, the battery-type electrode materials for Li-ion or Na-ion storage in aqueous electrolyte generally suffer from low capacity. [17][18][19] Thus, it is necessary to construct new HSCs based on other metal ion in aqueous electrolyte. Recently, more and more research attentions have been turned to aqueous zinc-ion batteries (ZIBs). While the short cycle life is the biggest drawback of aqueous ZIBs, the advantages of aqueous ZIBs-such as high capacity, high energy density, and high level of safety-cannot be ignored. [20][21][22] These provide us a new route for assembling aqueous Zinc-ion HSCs (ZHSCs) with zinc metal battery-type electrodes and suitable capacitor-type electrodes. In this respect, activated carbon (AC) as a common electrode material for HSCs was applied in recent reports. [23][24][25] However, AC-based electrodes for HSCs have several defects: i) AC-based electrodes require binder, conductive-additive and metal current collector, which increases the total weight, and thus decrease the final specific capacitance of the devices. ii) AC-based electrodes that store energy by using the energy storage mechanism of electrochemical double-layer capacitors have limited capacities. Therefore, it is necessary to develop new capacitor-type electrodes without binder and conductive-additive.MXene is a new group of 2D materials. Since the MXene was first reported in 2011, [26] it has attracted much attention due to the excellent metallic electrical conductivity, hydrophilic surface, and especially the pseudocapacitance energy storage mechanism in the field of SCs. [27][28][29][30][31] These features make MXene particularly attractive for capacitor-type electrodes of the ZHSCs. However, similar to graphene, adjacent MXene nanosheets are prone to aggregation and self-restacking under the van der Waals interaction, [32] which reduces their interlayer spacing, limits the electrolyte ions transport and hinders the sufficient Although current energy storage devices are limited by their own shortcomings, their merits such as superior power density and cycling stability for supercapacitors (SCs), and high energy density for batteries cannot be ignored either. Constructing hybrid SCs (HSCs) with capacitor-type electrodes and battery-type electrodes can combine the advantages of SCs and batteries. Herein, a zinc-ion HSC (ZHSC) is fabricated with a porous 3D MXene (Ti 3 C 2 T x )-reduced graphene oxide aerogel cathode and zinc foil an...

Low-Temperature Growing Anatase TiO2/SnO2 Multi-dimensional Heterojunctions at MXene Conductive Network for High-Efficient Perovskite Solar Cells

“…As shown in Fig. S1d and its inset, it is observed that the thickness of 2D MXene sheet is about 2.2 nm, which is close to the 1.5 nm thickness of monolayer MXene in our previous work [31]. As shown in XRD measure in Fig.…”

“…As a new group of 2D materials, the MXene is constructed of M N+1 X N T X structure, where the M represents an early transition metal such as Ti, and the X representing C and/or N element, and the T X meaning the terminal functional groups [26]. With its excellent metallic electrical conductivity, hydrophilic surface, and pseudocapacitance properties, the MXene has been explored as electrode materials for solar cells [27][28][29], zinc-ion capacitors [26,30], supercapacitors [31], or sensors [32]. In PSC application, it has also been reported that the PCE can be enhanced on the basis of the improved functional layers with MXene dopant.…”

Electrochemical Zinc Ion Capacitors Enhanced by Redox Reactions of Porous Carbon Cathodes

“…The ZIC can still deliver a gravimetric specific capacitance of 112.2 F g −1 even at a high current density of 60 A g −1 , demonstrating its superior rate capability. Notably, an ultrahigh power density of 48.8 kW kg −1 with a correspondingly high energy density of 40.4 Wh kg −1 can be achieved at a current density of 60 A g −1 , which is the highest value among the ZICs [ 11,13,15,19,20,22,37–43 ] and ZIBs [ 12,44–48 ] reported recently. Considering ZIC with PC800 cathode can deliver twice the energy density and six times the power density of the ZIC with commercial YP‐50F cathode (50.2 Wh kg −1 and 7.4 kW kg −1 ), [ 49 ] we believe our ZIC with PC800 cathode is a promising device for practical energy storage applications.…”

Symmetric, Asymmetric, and Battery‐Type Supercapacitors Using Two‐Dimensional Nanomaterials and Composites

“…An aqueous electrolyte-based battery-type zinc-ion hybrid supercapacitor was fabricated using MXene/rGO aerogel. [32] The zinc-ion hybrid supercapacitor was fabricated using porous Ti 3 C 2 T x MXene/rGO aerogel as the cathode, zinc Batteries & Supercaps foil as the anode, and M ZnSO 4 as the aqueous electrolyte. The MXene-rGO//Zn hybrid supercapacitor exhibited a high specific capacitance of 128.6 F/g and an energy density of 34.9 Wh/kg at a corresponding power density of 279.9 W/kg at a current density of 0.4 A/g.…”