Urea-induced interfacial engineering enabling highly reversible aqueous zinc-ion battery

Aqueous zinc-ion batteries(AZIBs)have been regarded as prospective rechargeable energy storage devices because of the high theoretical capacity and low redox potential of Zn metal.However,the uncontrollable formation of dendrites and the water-induced side reactions at the Zn/electrolyte interface,and the poor reversibility under a high current density(>2 mA·cm^(-2))and large area capacity(>2 mAh·cm^(-2))still limit the practical applications of AZIBs.Therefore,a strategy that can overcome these difficulties is urgently needed.Here,we introduce an environmentally friendly and low-cost additive,namely urea,to the electrolyte of AZIBs to induce uniform Zn deposition and suppress the side reactions.Measurements of the adsorption behavior,electrochemical characterization,and observations of the morphology revealed the interfacial modification induced by urea on the Zn/electrolyte interface,demonstrating its huge potential in AZIBs.Consequently,the long-term cycling stability(over2100 h)of a Zn/Zn symmetric cell under a high current density of 5 mA·cm^(-2)and a capacity of 5 mAh·cm^(-2)was achieved with a 1 mol·L^(-1)ZnSO_(4)electrolyte with the urea additive.Additionally,the assembled Zn/NH_4V_4O_(10)full cell with urea exhibited excellent cycling performance and an outstanding average Coulombic efficiency of 99.98%.These results indicate that this is a low-cost and effective additive strategy for realizing highly reversible AZIBs.

Theoretical research into low-voltage Na_(2)TiSiO_(5)anode for lithium-ion battery

Na_(2)TiSiO_(5)(NTSO)is a low-cost Li-ion battery anode with great application potential,such as the tetragonal NTSO(T-NTSO)with a high capacity and a low voltage.In addition to the tetragonal structure,NTSO has two other polymorphs.However,the basic understanding of the structure,ion insertion and transport mechanisms of these new materials is still lacking.Herein,we present a combined experimental and computational investigation of the tetragonal and orthorhombic NTSO to reveal the intrinsic mechanism leading to the superior electrochemical performance of T-NTSO.We determined that the insertion site with a flexible Ti^(4+)/Ti^(3+)redox pair is critical for Li+insertion stability.The large number of such flexible sites in the T-NTSO results in a higher capacity and higher ionic conductivity than those of orthorhombic polymorph.The understanding of intrinsic properties will accelerate the development and utilization of titanosilicates as the next generation low-voltage anode of Li-ion battery.