Building stabilized Cu_(0.17)Mn_(0.03)V_(2)O_(5−□)·2.16H_(2)O cathode enables an outstanding room‐/low‐temperature aqueous Zn‐ion batteries

Vanadium oxide cathode materials with stable crystal structure and fast Zn^(2+)storage capabilities are extremely important to achieving outstanding electrochemical performance in aqueous zinc‐ion batteries.In this work,a one‐step hydrothermal method was used to manipulate the bimetallic ion intercalation into the interlayer of vanadium oxide.The pre‐intercalated Cu ions act as pillars to pin the vanadium oxide(V‐O)layers,establishing stabilized two‐dimensional channels for fast Zn^(2+)diffusion.The occupation of Mn ions between V‐O interlayer further expands the layer spacing and increases the concentration of oxygen defects(Od),which boosts the Zn^(2+)diffusion kinetics.As a result,as‐prepared Cu_(0.17)Mn_(0.03)V_(2)O_(5−□)·2.16H_(2)O cathode shows outstanding Zn‐storage capabilities under room‐and lowtemperature environments(e.g.,440.3 mAh g^(−1)at room temperature and 294.3 mAh g^(−1)at−60°C).Importantly,it shows a long cycling life and high capacity retention of 93.4%over 2500 cycles at 2 A g^(−1)at−60°C.Furthermore,the reversible intercalation chemistry mechanisms during discharging/charging processes were revealed via operando X‐ray powder diffraction and ex situ Raman characterizations.The strategy of a couple of 3d transition metal doping provides a solution for the development of superior room‐/lowtemperature vanadium‐based cathode materials.

Polysulfide regulation by defect-modulated Ta_(3)N_(5-x) electrocatalyst toward superior room-temperature sodium-sulfur batteries

Resolving low sulfur reaction activity and severe polysulfide dissolution remains challenging in metalsulfur batteries.Motivated by a theoretical prediction,herein,we strategically propose nitrogenvacancy tantalum nitride(Ta3N5-x)impregnated inside the interconnected nanopores of nitrogendecorated carbon matrix as a new electrocatalyst for regulating sulfur redox reactions in roomtemperature sodium-sulfur batteries.Through a pore-constriction mechanism,the nitrogen vacancies are controllably constructed during the nucleation of Ta3N5-x.The defect manipulation on the local environment enables well-regulated Ta 5d-orbital energy level,not only modulating band structure toward enhanced intrinsic conductivity of Ta-based materials,but also promoting polysulfide stabilization and achieving bifunctional catalytic capability toward completely reversible polysulfide conversion.Moreover,the interconnected continuous Ta3N5-x-in-pore structure facilitates electron and sodium-ion transport and accommodates volume expansion of sulfur species while suppressing their shuttle behavior.Due to these attributes,the as-developed Ta3N5-x-based electrode achieves superior rate capability of 730 mAh g-1 at 3.35 A g-1,long-term cycling stability over 2000 cycles,and high areal capacity over 6 mAh cm-2 under high sulfur loading of 6.2 mg cm-2.This work not only presents a new sulfur electrocatalyst candidate for metal-sulfur batteries,but also sheds light on the controllable material design of defect structure in hopes of inspiring new ideas and directions for future research.