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A fast ion conductor, NaTi2(PO4)3 (NTP), is hydrothermally synthesized as a solid‐state electrolyte protection layer on the surface of Zn anodes (NTP@Zn). NTP has fast ionic conductivity compared with other insoluble phosphates, such as TiP2O7 (TPO) and Zn3(PO4)2 (ZPO), which is demonstrated by the density‐functional theory calculation and cyclic voltammetry tests. X‐ray photoelectron spectrometer, X‐ray powder diffraction, and HRTEM analyses show that the internal transport/mobility of Zn2+ can be achieved in NTP layer as an "ion passable fence." The NTP layer with a thickness of 20–25 µm not only prevents side reactions and zinc dendrites, but also improves the reversibility of Zn deposition and electrochemical performance. The NTP@Zn/MnO2 battery represents the best long‐life performance among Zn/MnO2 batteries to date, which successfully retains a considerable capacity of 105 mA h g−1 with a CE nearly 100% after 10 000 charge/discharge cycles at 10 C (≈1.5 A g−1). Each cycle capacity attenuation rate is only 0.004%. This work represents an advanced step toward long‐life Zn metal anodes for aqueous zinc‐ion batteries. [ABSTRACT FROM AUTHOR]

Sulfur‐deficient TiS2–x is prepared through high temperature vacuum annealing. Electron spin resonance (ESR) and X‐ray photoelectron spectroscopy (XPS) data confirm the presence of sulfur vacancies in TiS2–x. Effective polysulfide adsorption and promotion to polysulfide redox conversion was proven by adsorption simulation experiments and electrochemical measurements. Thus, TiS2–x is used as cathode promoter for Li−S half‐cells to improve the overall electrochemical performance. As expected, the TiS2–x/S electrode shows a high and stable capacity of 751 mAh g−1 even after 500 cycles and a fade rate as low as 0.04 % per cycle at 1 C. Besides, the high sulfur loading of the electrode of 4 mg cm−2 also displays an admirable cycling performance of 963 mAh g−1 with a capacity retention up to 91.7 % over 50 cycles at 0.2 C. [ABSTRACT FROM AUTHOR]

Aqueous Zn-metal batteries are of great interest due to their high material abundance, low production cost, and excellent safety. However, they suffer from severe side reactions and notorious dendrite growth closely related to electrolytes. Here, in-situ generated zwitterionic polymers are used as gel electrolytes to overcome these problems. It is shown that anions and H2O, but not anions and cations, are preferentially immobilized at different sites of zwitterionic polymers, facilitating the free migration of Zn2+ and reducing the side reactions. This immobilization can be associated with the dipole moment of zwitterionic polymers. As a result, poly[3-dimethyl(methacryloyl oxyethyl) ammonium propane sulfonate] (PDMAPS) stands out from a series of zwitterionic polymers and outperforms the other candidates in electrochemical performance. The symmetric cells using PDMAPS smoothly operate ~9000 h at 0.5 mA cm-2 for 0.5 mAh cm-2, much better than the controls. Moreover, PDMAPS enables an Ah-level pouch cell for continuous cycling. These results not only benefit the rational molecular design of advanced electrolytes, but also demonstrate the promising potential of zwitterionic polymers in aqueous Zn-metal batteries., (© 2024 Wiley‐VCH GmbH.)

Constructing dual-site catalysts consisting of atomically dispersed metal single atoms and metal atomic clusters (MACs) is a promising approach to further boost the catalytic activity for oxygen reduction reaction (ORR). Herein, a porous Co SA-AC @SNC featuring the coexistence of Co single-atom sites (CoN 4 ) and S-coordinated Co atomic clusters (SCo 6 ) in S, N co-doped carbon substrate is successfully synthesized by using porphyrinic metal-organic framework (Co-TPyP MOF) as the precursor. The introduction of the sulfur source creates abundant microstructural defects to anchor Co metal clusters, thus modulating the electronic structure of its surrounding carbon substrate. The synergistic effect between the two types of active sites and structural advantages, in turn, results in high ORR performance of Co SA-AC @SNC with half-wave potential (E 1/2 ) of 0.86 V and Tafel slope of 50.17 mV dec -1 . Density functional theory (DFT) calculations also support the synergistic effect between CoN 4 and SCo 6 by detailing the catalytic mechanism for the improved ORR performance. The as-fabricated Zn-air battery (ZAB) using Co SA-AC @SNC demonstrates impressive peak power density of 174.1 mW cm -2 and charge/discharge durability for 148 h. This work provides a facile synthesis route for dual-site catalysts and can be extended to the development of other efficient atomically dispersed metal-based electrocatalysts., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Designing and fabricating efficient and stable nonprecious metal-based oxygen reduction reaction (ORR) electrocatalysts is a pressing and challenging task for the pursuit of sustainable new energy devices. Herein, porous P-CoSe 2 @NC electrocatalysts with high-density carbon-coated CoSe 2 sites were successfully fabricated based on a pyridyl-porphyrinic metal-organic framework (Co-TPyP MOF) via a molten salt-assisted synthesis method. The hierarchical pore and N-doping carbon substrate of P-CoSe 2 @NC promotes mass transfer and electron-transfer efficiency, which is beneficial to maximize CoSe 2 site utilization. Well-designed P-CoSe 2 @NC exhibits efficient ORR catalytic activity with a high half-wave potential of 0.863 V and excellent catalytic stability. Meanwhile, rechargeable aqueous primary/quasi-solid-state ZABs based on a P-CoSe 2 @NC air cathode show a high peak power density and exceptional operating stability, catering to the demands of practical applications. The qualified performance and structure stability of the electrocatalytic system may be mainly attributed to the protection of the CoSe 2 nanoparticle by the coated carbon layer. Given the rational design of the structure and the component of the electrocatalyst with enhanced ORR activity, we believe that this work has provided a reliable pathway to the development of high-performance transition-metal chalcogenides for energy-storage and -conversion devices.

Aqueous rechargeable Zn/birnessite batteries have recently attracted extensive attention for energy storage system because of their low cost and high safety. However, the reaction mechanism of the birnessite cathode in aqueous electrolytes and the cathode structure degradation mechanics still remain elusive and controversial. In this work, it is found that solvation water molecules coordinated to Zn 2+ are coinserted into birnessite lattice structure contributing to Zn 2+ diffusion. However, the birnessite will suffer from hydroxylation and Mn dissolution with too much solvated water coinsertion. Through engineering Zn 2+ primary solvation sheath with strong-field ligand in aqueous electrolyte, highly reversible [Zn(H 2 O) 2 ] 2+ complex intercalation/extraction into/from birnessite cathode is obtained. Cathode-electrolyte interface suppressing the Mn dissolution also forms. The Zn metal anode also shows high reversibility without formation of "death-zinc" and detrimental dendrite. A full cell coupled with birnessite cathode and Zn metal anode delivers a discharge capacity of 270 mAh g -1 , a high energy density of 280 Wh kg -1 (based on total mass of cathode and anode active materials), and capacity retention of 90% over 5000 cycles., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)