Ethylene glycol-regulated ammonium vanadate with stable layered structure and favorable interplanar spacing as high-performance cathode for aqueous zinc ion batteries

Ammonium vanadate compounds featuring large capacity,superior rate capability and light weight are regarded as promising cathode materials for aqueous zinc ion batteries(AZIBs).However,the controllable synthesis of desired ammonium vanadates remains a challenge.Herein,various ammonium vanadate compounds were successfully prepared by taking advantage of ethylene glycol(EG)regulated polyolreduction strategy and solvent effect via hydrothermal reaction.The morphology and crystalline phase of resultant products show an evolution from dendritic(NH_(4))_(2)V_(6)O_(16)to rod-like NH_(4)V_(4)O_(10)and finally to lamellar(NH4)2V4O9 as increasing the amount of EG.Specifically,the NH_(4)V_(4)O_(10)product exhibits a high initial capacity of 427.5 mAh/g at 0.1 A/g and stable cycling with a capacity retention of 90.4%after 5000 cycles at 10 A/g.The relatively excellent electrochemical performances of NH_(4)V_(4)O_(10)can be ascribed to the stable open-framework layered structure,favorable(001)interplanar spacing,and peculiar rod-like morphology,which are beneficial to the highly reversible Zn^(2+)storage behaviors.This work offers a unique way for the rational design of high-performance cathode materials for AZIBs.

Synthesis of Nafion^(■)-stabilized Pt nanoparticles to improve the durability of proton exchange membrane fuel cell

Nafion-stabilized Pt nanoparticle colloidal solution is synthesized through ethylene glycol reduction.Pt/Nafion added with carbon black as electric conduction material（labeled Pt/Nafion-XC72） shows excellent electrochemical property compared with Pt/C.After a 300-cycle discharging durability test,the cell performance of membrane electrode assembly（MEA） with the Pt/Nafion-XC72 and Pt/C catalysts indicates a 29.9% and 92.2% decrease,respectively.The charge transfer resistances of Pt/Nafion-XC72 and Pt/C increase by 27.2% and 101.9%,respectively.The remaining electrochemically active surface area of Pt is about 61.7% in Pt/Nafion-XC72 and about 38.1% in Pt/C after the durability test.The particle size of Pt/C increases from about 5.1 nm to about 10.8 nm but only from 3.6 nm to 5.8 nm in the case of Pt/Nafion-XC72.These data suggest that Pt/Nafion-XC72 as a catalyst can enhance the durability of PEMFCs compared with Pt/C.