An in-depth understanding of improvement strategies and corresponding characterizations towards Zn anode in aqueous Zn-ions batteries

Combining the unique advantages of aqueous electrolytes and metallic Zn anode, rechargeable aqueous Zn-ion batteries(ZIBs) are of great promise for large-scale energy storage applications due to their inherent high safety, low cost, and environmental friendliness. As the essential component of ZIBs, Zn metal anode suffers from severe dendrite formation and inevitable side reactions(e.g. corrosion and hydrogen evolution)in aqueous electrolytes, which leads to low Coulombic efficiency and inferior cycling stability, impeding their large-scale applications. To be compatible with satisfactory aqueous ZIBs, Zn anode has been modified from various perspectives and focus areas. Herein, based on their intrinsic characteristics, we review the related improvement strategies for Zn anode, including interphase, substrate, and bulk design, so as to achieve an in-depth understanding of Zn anode optimization. Furthermore, the timely summary of characterization methods for Zn anodes are also performed for the first time, from both thermodynamic and kinetics perspectives, which is particularly helpful for beginners to understand the complicated characterizations and employ suitable methods. Finally, certain noteworthy points are put forward for subsequent investigation of aqueous ZIBs. It is expected that this review will enlighten researchers to explore more efficient optimization strategies for Zn anode in aqueous electrolytes.

Processable Potassium Metal Anode for Stable Batteries

The future of high-energy density electrochemical energy storage systems relies on the advancement of rechargeable batteries that utilize reactive metals as anodes.In the alkaline metal,secondary battery systems because of abundant resource,high capacity and low redox potential,potassium(K)metal secondary battery(KMB)is expected to replace the existing lithiumion battery as a versatile platform for high-energy density,cost-effective energy storage devices.However,the difficulty in processing metal K results in nonstandard electrodes and hinders the development of KMBs.Furthermore,the mobility of the K metal anode due to its unique lowmelting point character at elevated temperatures in practical conditions leads to severe instability and risks in chemical/electrochemical processes.Herein,we fabricate a processable and moldable composite K metal anode by encapsulating K into reduced graphene oxide(rGO).The composite electrode can be engineered into various shapes discretionarily with precise sizes and stabilize the K metal anode at relatively high temperatures.Remarkably,the composite anode exhibits excellent cycling performance at high current density(8 mA cm^(-2)) with dendrite-free morphology.Paired with a Prussian blue cathode,the rGO-K composite anode shows much improved electrochemical performance and extended lifetime.

Numerical studies of static aeroelastic effects on grid fin aerodynamic performances

The grid fin is an unconventional control surface used on missiles and rockets. Although aerodynamics of grid fin has been studied by many researchers, few considers the aeroelastic effects.In this paper, the static aeroelastic simulations are performed by the coupled viscous computational fluid dynamics with structural flexibility method in transonic and supersonic regimes. The developed coupling strategy including fluid–structure interpolation and volume mesh motion schemes is based on radial basis functions. Results are presented for a vertical and a horizontal grid fin mounted on a body. Horizontal fin results show that the deformed fin is swept backward and the axial force is increased. The deformations also induce the movement of center of pressure, causing the reduction and reversal in hinge moment for the transonic flow and the supersonic flow,respectively. For the vertical fin, the local effective incidences are increased due to the deformations so that the deformed normal force is greater than the original one. At high angles of attack, both the deformed and original normal forces experience a sudden reduction due to the interference of leeward separated vortices on the fin. Additionally, the increment in axial force is shown to correlate strongly with the increment in the square of normal force.