No abstract

K-ion battery (KIB) is a new-type energy storage device that possesses potential advantages of low-cost and abundant resource of K precursor materials. However, the main challenge lies on the lack of stable materials to accommodate the intercalation of large-size K-ions. Here we designed and constructed a novel earth abundant Fe/Mn-based layered oxide interconnected nanowires as a cathode in KIBs for the first time, which exhibits both high capacity and good cycling stability. On the basis of advanced in situ X-ray diffraction analysis and electrochemical characterization, we confirm that interconnected KFeMnO nanowires can provide stable framework structure, fast K-ion diffusion channels, and three-dimensional electron transport network during the depotassiation/potassiation processes. As a result, a considerable initial discharge capacity of 178 mAh g is achieved when measured for KIBs. Besides, K-ion full batteries based on interconnected KFeMnO nanowires/soft carbon are assembled, manifesting over 250 cycles with a capacity retention of ∼76%. This work may open up the investigation of high-performance K-ion intercalated earth abundant layered cathodes and will push the development of energy storage systems.

Rechargeable aqueous Zn-based batteries, benefiting from their good reliability, low cost, high energy/power densities, and ecofriendliness, show great potential in energy storage systems. However, the poor cycling performance due to the formation of Zn dendrites greatly hinders their practical applications. In this work, a trilayer 3D CC-ZnO@C-Zn anode is obtained by in situ growing ZIFs (zeolitic-imidazolate frameworks) derived ZnO@C coreshell nanorods on carbon cloth followed by Zn deposition, which exhibits excellent antidendrite performance. Using CC-ZnO@C-Zn as the anode and a branch-like Co(CO 3 ) 0.5 (OH) x ·0.11H 2 O@CoMoO 4 (CC-CCH@CMO) as the cathode, a Zn-Co battery is rationally designed, displaying excellent energy/power densities (235 Wh kg −1 , 12.6 kW kg −1 ) and remarkable cycling performance (71.1% after 5000 cycles). Impressively, when using a gel electrolyte, a highly customizable, fiber-shaped flexible all-solid-state Zn-Co battery is assembled for the first time, which presents a high energy density of 4.6 mWh cm −3 , peak power density of 0.42 W cm −3 , and long durability (82% capacity retention after 1600 cycles) as well as excellent flexibility. The unique 3D electrode design in this study provides a novel approach to achieve high-performance Zn-based batteries, showing promising applications in flexible and portable energy-storage systems.

Electrocatalytic water splitting is one of the sustainable and promising strategies to generate hydrogen fuel but still remains a great challenge because of the sluggish anodic oxygen evolution reaction (OER). A very effective approach to dramatically decrease the input cell voltage of water electrolysis is to replace the anodic OER with hydrazine oxidation reaction (HzOR) due to its lower thermodynamic oxidation potential. Therefore, developing the low-cost and efficient HzOR catalysts, coupled with the cathodic hydrogen evolution reaction (HER) is tremendously important for energysaving electrolytic hydrogen production. Herein, a new-type copper-nickel nitride (Cu 1 Ni 2 -N) with rich Cu 4 N/Ni 3 N interface is rationally constructed on the carbon fiber cloth. The three-dimensional electrode exhibits extraordinary HER performance with an overpotential of 71.4 mV at 10 mA cm -2 in 1.0 M KOH, simultaneously delivering an ultralow potential of 0.5 mV at 10 mA cm -2 for HzOR in 1.0 M KOH/0.5 M hydrazine electrolyte. Moreover, the electrolytic cell utilizing the synthesized Cu 1 Ni 2 -N electrode as both the cathode and anode displays a cell voltage of 0.24 V at 10 mA cm -2 with an excellent stability over 75 h. The present work develops the promising copper-nickel-based nitride as a bifunctional electrocatalyst through hydrazine-assistance for energy-saving electrolytic hydrogen production.

This review article summarizes the recent advances in versatile synthesis strategies and broad applications of metal–organic framework coatings.

Although there has been tremendous progress in exploring new configurations of zinc‐ion hybrid supercapacitors (Zn‐HSCs) recently, the much lower energy density, especially the much lower areal energy density compared with that of the rechargeable battery, is still the bottleneck, which is impeding their wide applications in wearable devices. Herein, the pre‐intercalation of Zn2+ which gives rise to a highly stable tunnel structure of ZnxMnO2 in nanowire form that are grown on flexible carbon cloth with a disruptively large mass loading of 12 mg cm−2 is reported. More interestingly, the ZnxMnO2 nanowires of tunnel structure enable an ultrahigh areal energy density and power density, when they are employed as the cathode in Zn‐HSCs. The achieved areal capacitance of up to 1745.8 mF cm−2 at 2 mA cm−2, and the remarkable areal energy density of 969.9 µWh cm−2 are comparable favorably with those of Zn‐ion batteries. When integrated into a quasi‐solid‐state device, they also endow outstanding mechanical flexibility. The truly battery‐level Zn‐HSCs are timely in filling up of the battery‐supercapacitor gap, and promise applications in the new generation flexible and wearable devices.

further development. [2] Hence, exploring novel approaches to achieve more efficient energy storage is highly demanded. Recently, aqueous batteries are attracting unprecedented attention particularly owing to their high safety, high ion conductivity, low cost, and environmental friendliness. [3] To date, numerous aqueous batteries based on Li + , Na + , K + , Mg 2+ , Ca 2+ , Zn 2+ , Al 3+ , Fe 3+ , and/or mixed metal ions as charge carriers have been reported, [4] which find potential applications in fields such as grid-scale energy storage, wearable devices, and etc. [5] Among them, as a promising candidate, the rechargeable aqueous Zn-based batteries (AZBs) including Zn-ion batteries (mild electrolyte), [6] Zn-Co/Ag/ Ni alkaline batteries [7] and Zn-air batteries in alkaline electrolyte [8] have been extensively studied due to their unparalleled advantages of Zn anode. In general, metal Zn has the features of high theoretical capacity (820 mAh g −1 ), high electrical conductivity, nontoxicity, easy processing, and suitable redox potential (−0.76 V vs standard hydrogen electrode). [9] However, most of AZBs reported so far have encountered the same challenges, which are the narrow voltage window, unsatisfactory capacity, and poor cycling performance. [10] For example, all Zn-ion batteries operated in mild electrolyte including Zn//V-based, Zn//Mn-based, and Zn//Prussian blue analogs-based hold a narrow voltage window of 0.3-1.6, 0.9-1.8, and 0.2-1.8 V, respectively. [11] Even though AZBs in alkaline electrolyte display a higher voltage than that achieved in mild medium, their voltage windows are still only about 1.2-1.9 V. [12] Meanwhile, the alkaline electrolytes show stronger corrosion than mild neutral electrolytes, which greatly limit their wide applications. Moreover, the unstable cycling performance in AZBs due to the Zn dendrites and side reaction on the surface of Zn anode is also unsatisfactory. [10] To date, the electrolyte optimization or structural design are the common ways to suppress the growth of Zn dendrite and improve the cycling stability. For example, Chen and co-workers reported that aqueous electrolyte Zn(CF 3 SO 3 ) 2 can suppress the formation of detrimental dendrites in AZBs owing to the better reversibility and faster kinetics of Zn deposition/dissolution than that in ZnSO 4 electrolyte. [13] However, Zn(CF 3 SO 3 ) 2 is too expensive (≈$ 8.1 g −1 , prices from Sigma-Aldrich) to be applied With the increasing energy crisis and environmental pollution, rechargeable aqueous Zn-based batteries (AZBs) are receiving unprecedented attention due to their list of merits, such as low cost, high safety, and nontoxicity. However, the limited voltage window, Zn dendrites, and relatively low specific capacity are still great challenges. In this work, a new reaction mechanism of reversible Mn 2+ ion oxidation deposition is introduced to AZBs. The assembled Mn 2+ /Zn 2+ hybrid battery (Mn 2+ /Zn 2+ HB) based on a hybrid storage mechanism including Mn 2+ ion deposition, Zn 2+ ion insertion, and co...

Porous V2O5 microspheres synthesized by a spray-drying method exhibit an ultrahigh reversible capacity and superior rate and cycling performances in aqueous ZIBs.