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[Display omitted] Aqueous rechargeable batteries offer a safe alternative for electrochemical energy storage, integrating cost-efficiency and energy density to meet the demand for stationary applications. Recent efforts have focused on the improvement of electrode materials in aqueous electrolytes, particularly the cycle life and energy reliability of batteries. The anion intercalation chemistry in graphite could be an alternative cathode candidate, often requiring an upper cut-off potential above 4.5 V vs. Li+/Li. Such a potential readily exceeds the electrochemical stability windows of water-based electrolytes. Herein, we provide a progress report and critical comment on the reversible intercalation chemistry in graphite compounds, i.e. , anion and halogen intercalations, for the development of economical, high-energy aqueous rechargeable batteries. In addition, this review focuses on the charge carrier species, their charge storage mechanisms and battery configurations, aiming to provide solutions to solve the remaining key challenges for aqueous batteries. [ABSTRACT FROM AUTHOR]

Abstract: A novel network LiFePO4/C composite was prepared by mixing precursor solution with carbon aerogel (CA) via a simple solution impregnation method, characterized by XRD, SEM, EDS and electrochemical analysis. The results revealed that the LiFePO4 nanowire forming on the ektexine of CA intertwined with LiFePO4/CA particles and formed a special web structure. The initial discharge capacity was improved to be 139.3 mAh g−1 at 10 C and the capacity retention is near 100% after 50 cycles. The web structure could improve electron transport and electrochemical activity effectively. [Copyright &y& Elsevier]

[Display omitted] • The tunnel-type Ti-substituted Na 0.44 MnO 2 was investigated as cathode for aqueous zinc batteries. • The Ti-substitution can efficiently improve the electrochemical kinetics with superior high-rate capability and cycling stability. • The facilitated reaction mechanism with stepwise Zn2+ and H+ insertions was versified. • The optimal Na 0.44 Mn 0.78 Ti 0.22 O 2 material exhibits a high reversible capacity and a cycling life record for 2400 cycles. The tunnel-type sodium manganese oxide (Na 0.44 MnO 2) materials are considered as promising cathode candidates for rechargeable batteries due to their low cost and sustainability. However, the direct implementation in aqueous batteries, as an emerging energy storage technology, was not fully realized in terms of the reversibility and long-cycling stability. Herein, the tunnel-type Ti-substituted Na 0.44 MnO 2 (NMTO) is investigated as a cathode material for aqueous zinc-metal batteries. It is identified that the Ti-substitution has a significant effect on improving its rate capability and cycling stability. As a result, the optimal Na 0.44 Mn 0.78 Ti 0.22 O 2 (NMTO-0.22) material exhibits a reversible capacity of 109.6 mAh/g at 1.0 A g−1, and 71% of the initial capacity can be retained after 2400 cycles. Such performance can be attributed to the enhanced insertion mechanisms in the tunnel structure, as verified by the post-mortem spectroscopic and microscopic techniques. Density functional theory (DFT) calculations enclose that the average charge density in Mn 3d orbits near the Fermi level and Mn participation in redox reaction are improved after Ti-substitution, supporting the facilitated electrochemical kinetics of NMTO. This work demonstrates that the Ti-substituted Na 0.44 MnO 2 is a promising cathode material for aqueous zinc-metal batteries, and provides a fundamental understanding on the charge storage mechanisms. [ABSTRACT FROM AUTHOR]

Abstract: Using different gas source, four types of diamond thin films were prepared on silicon substrate by microwave plasma chemical vapor deposition (MPCVD) technology, and characterized in detail through scanning electron microscopy (SEM), Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy. High-current pulsed emission characteristics, tested with a 2MeV line-inducing injector, showed that all of CVD diamond films had high emission current density (>70A/cm2) and [100] textured B-doped microcrystalline diamond film possessed the largest emission current density of 115.1A/cm2. No obvious bright light and luminescent zones from side view CCD images indicated a possible pure field-emission mechanism of these diamond cathodes. Simultaneously, large decrease in the electron emission capability, above 15%, could be observed after several pulsed measurements, but this decrease could be completely recovered through the treatment of surface re-hydrogenation for emitted diamond cathodes, suggesting that emission performance of CVD diamond cathodes was closely relevant to hydrogen coverage ratio. The present data indicated that as-deposited CVD diamond films could be a potential candidate as cold cathode for the application in high-current electron emission field. [Copyright &y& Elsevier]