Advances in doping strategies for sodium transition metal oxides cathodes:A review

The electrochemistry of cathode materials for sodium-ion batteries differs significantly from lithium-ion batteries and offers distinct advantages.Overall,the progress of commercializing sodium-ion batteries is currently impeded by the inherent inefficiencies exhibited by these cathode materials,which include insufficient conductivity,slow kinetics,and substantial volume changes throughout the process of intercalation and deintercalation cycles.Consequently,numerous methodologies have been utilized to tackle these challenges,encompassing structural modulation,surface modification,and elemental doping.This paper aims to highlight fundamental principles and strategies for the development of sodium transition metal oxide cathodes.Specifically,it emphasizes the role of various elemental doping techniques in initiating anionic redox reactions,improving cathode stability,and enhancing the operational voltage of these cathodes,aiming to provide readers with novel perspectives on the design of sodium metal oxide cathodes through the doping approach,as well as address the current obstacles that can be overcome/alleviated through these dopant strategies.

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.

Flare and change in disease activity among patients with stable rheumatoid arthritis following coronavirus disease 2019 vaccination:A prospective Chinese cohort study

Background:Vaccination has been shown effective in controlling the global coronavirus disease 2019(COVID-19)pandemic and reducing severe cases.This study was to assess the flare and change in disease activity after COVID-19 vaccination in patients with stable rheumatoid arthritis(RA).Methods:A prospective cohort of RA patients in remission or with low disease activity was divided into a vaccination group and a non-vaccination group based on their COVID-19 vaccination status.Each of them was examined every 3 to 6 months.In the vaccination group,disease activity was compared before and after vaccination.The rates of flare defined as disease activity scores based on 28-joint count(DAS28)>3.2 withΔDAS28≥0.6 were compared between vaccination and non-vaccination groups.Results:A total of 202 eligible RA patients were enrolled.Of these,98 patients received no vaccine shot(non-vaccination group),and 104 patients received two doses of vaccine(vaccination group).The median time interval from pre-vaccination visit to the first immunization and from the second dose of vaccine to post-vaccination visit was 67 days and 83 days,respectively.The disease activity scores at pre-vaccination and post-vaccination visits in the vaccination group patients were similar.At enrollment,gender,RA disease course,seropositivity,and disease activity were comparable across the two groups.Flare was observed in five(4.8%)of the vaccination group patients and nine(9.2%)of the non-vaccination group patients at post-vaccination assessment(P=0.221).In terms of safety,29(27.9%)patients experienced adverse events(AEs)after vaccination.No serious AEs occurred.Conclusions:COVID-19 vaccinations had no significant effect on disease activity or risk of flare in RA patients in remission or with low disease activity.Patients with stable RA should be encouraged to receive the COVID-19 vaccination.