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• The few-layered MoS 2 nanosheets with different phase contents were prepared by an efficient controllable phase engineering. • The optimized material shows outstanding specific capacity and excellent long cycling performances. • The mechanisms involved were elucidated by systematical characterizations. • The DFT simulations reveal that the 1T phase MoS 2 has much lower Zn diffusion energy barriers. Recently, aqueous rechargeable Zn-ion batteries have attracted extensive attention, owing to their low-cost, high operational safety and environmental friendliness. However, the aqueous zinc-ion battery is still in a very infant stage, and the main challenge is to develop the ideal cathode due to the sluggish kinetics and low reversibility of divalent zinc ions. Herein, for the first time, we report controllable phase engineered few-layered MoS 2 nanosheet as cathode materials for rechargeable aqueous Zn-ion batteries and systematically study their performance. We found that the obtained MoS 2 with different phase contents showed distinct performance in the rechargeable aqueous zinc-ion battery. In particular, the MoS 2 nanosheets with ~70% 1T phase content displays excellent specific capacity and shows outstanding long-term cyclic stability. The mechanisms involved were clarified by not only comprehensive characterizations, but also the density functional theory (DFT) simulations that reveal the 1T phase MoS 2 has much lower Zn diffusion energy barriers. This study provides new insight into the effect of different phases on the performance of MoS 2 -based electrodes and will improve our understanding of developing better cathodes for the aqueous rechargeable Zn-ion batteries. [ABSTRACT FROM AUTHOR]

Developing cathodes capable of working at intermediate temperatures (IT) is key to improving solid oxide fuel cells' (SOFC) durability, ease of operation, and manufacturing cost reduction. BaFeO 3-δ (BFO)-based perovskites are ideal candidates because of their fast kinetics, which is due to the mixed conduction of oxygen vacancies and electron-holes. Thus, maximizing their oxygen vacancy and hole concentration can further enhance oxygen reduction reaction (ORR) catalysis. This work proposes to achieve this by generating A-site deficiency, which introduces negative charges into the perovskite crystal. The paper presents a computational and experimental analysis of this strategy on BFO-based cathodes, using (Ba 0.95 La 0.05) 1-x FeO 3-δ as a case study. A-site deficiency increases the concentration of oxygen vacancies and holes, improving ORR catalysis. In addition, it eases oxygen surface exchange by hindering Ba segregation. As a result, A-site deficiency improves the overall electrochemical properties of BFO-based cathodes, providing a simple and effective method to enhance their performance. • A-site deficiency generates oxygen vacancies and electron holes in BaFeO 3-δ. • Oxygen vacancies boost the ionic conductivity. • Electron holes increase the electronic conductivity. • A-site deficient BaFeO 3-δ -based materials also show reduced Ba surface segregation. • A-site deficiency has an overall beneficial effect on the cathode performance. [ABSTRACT FROM AUTHOR]

Rechargeable aqueous zinc-ion batteries are emerged as fascinating "beyond Li-ion" battery technologies for large-scale energy storage due to low cost, high theoretical capacity, high safety and environmental friendliness. However, developing cathode materials with outstanding electrochemical performance are prerequisites. Herein, the a-V 2 O 5 @Ti 3 C 2 T x heterostructure is prepared by in situ incorporating amorphous V 2 O 5 with Ti 3 C 2 T x MXene to enhance the rechargeable aqueous Zn-ion batteries performance. Benefitting from the distinctive amorphous structure of a-V 2 O 5 , outstanding conductivity of Ti 3 C 2 T x MXene and the strong synergistic effect between two components, the a-V 2 O 5 @Ti 3 C 2 T x heterostructure presents isotropic ion diffusion paths, plentiful ion storage sites and splendid conductivity. As a consequence, the a-V 2 O 5 @Ti 3 C 2 T x heterostructure displays excellent specific capacity of 544 mAh g−1 at 0.5 A g−1 and outstanding rate performance. Particularly, even at a fairly high current density of 30 A g−1, the a-V 2 O 5 @Ti 3 C 2 T x heterostructure shows an impressive specific capacity of 135 mAh g−1 along with about 100% coulombic efficiency after 1000 cycles. Furthermore, the mechanism related is expounded via comprehensive characterizations. Therefore, this work offers a way for developing high-performance vanadium-based cathode materials for aqueous zinc-ion batteries. [Display omitted] • Amorphous V 2 O 5 @Ti 3 C 2 T x was fabricated via a simple in situ synthetic method. • Synergistic effect amorphous V 2 O 5 and Ti 3 C 2 T x endows fascinating properties. • The cathode presents outstanding specific capacity and cycling stability. • The mechanisms involved were elucidated via comprehensive characterizations. [ABSTRACT FROM AUTHOR]