Spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode candidate for the next‐generation high energy‐density lithium‐ion batteries (LIBs). Unfortunately, the application of LNMO is hindered by its poor cycle stability. Now, site‐selectively doped LNMO electrode is prepared with exceptional durability. In this work, Mg is selectively doped onto both tetrahedral (8a) and octahedral (16c) sites in the Fdtrue3‾ m structure. This site‐selective doping not only suppresses unfavorable two‐phase reactions and stabilizes the LNMO structure against structural deformation, but also mitigates the dissolution of Mn during cycling. Mg‐doped LNMOs exhibit extraordinarily stable electrochemical performance in both half‐cells and prototype full‐batteries with novel TiNb2O7 counter‐electrodes. This work pioneers an atomic‐doping engineering strategy for electrode materials that could be extended to other energy materials to create high‐performance devices.

devices and for various types of consumer electronics. All-solid-state rechargeable batteries (ASSBs) utilizing solid-electrolyte separators rather than combustible liquid electrolytes possess the inherent advantages of enhanced safety and stability for state-of-the-art battery technologies. [1] Recently, ASSBs have attracted a resurgence of interest as ideal candidates for the next generation of electrochemicalenergy-storage devices. The superiority of ASSBs could be ascribed to the distinctive attributes of solid-state electrolytes (SSEs), including high Li-ion transference number and safety, and comparable ionic conductivity to their liquid counterparts. [2] The adoption of SSEs could offer new opportunities for the high-temperature electrical-energy-storage market and pave the way for the utilization of high-capacity electrodes, such as Li, Na, and sulfur. [2c,3] In contrast, in conventional batteries employing liquid electrolytes, the highcapacity electrodes may meet with detrimental side reactions, causing problems such as dendrite growth, reactivity, and/ or dissolution in the solvent. [4,5] With the construction of rigid solid electrolyte separators and stable interfaces in ASSBs, dendrite growth can be effectively mitigated, thus improving the safety of the batteries. [4,6] Owing to these benefits, in battery research, the number of studies on fabricating superionic SSEs has grown rapidly. Despite great progress gained these years, issues Borohydride solid-state electrolytes with room-temperature ionic conductivity up to ≈70 mS cm −1 have achieved impressive progress and quickly taken their place among the superionic conductive solid-state electrolytes. Here, the focus is on state-of-the-art developments in borohydride solid-state electrolytes, including their competitive ionic-conductive performance, current limitations for practical applications in solid-state batteries, and the strategies to address their problems. To open, fast Li/Na/Mg ionic conductivity in electrolytes with BH 4 − groups, approaches to engineering borohydrides with enhanced ionic conductivity, and later on the superionic conductivity of polyhedral borohydrides, their correlated conductive kinetics/thermodynamics, and the theoretically predicted high conductive derivatives are discussed. Furthermore, the validity of borohydride pairing with coated oxides, sulfur, organic electrodes, MgH 2 , TiS 2 , Li 4 Ti 5 O 12 , electrode materials, etc., is surveyed in solid-state batteries. From the viewpoint of compatible cathodes, the stable electrochemical windows of borohydride solid-state electrolytes, the electrode/electrolyte interface behavior and battery device design, and the performance optimization of borohydride-based solid-state batteries are also discussed in detail. A comprehensive coverage of emerging trends in borohydride solid-state electrolytes is provided and future maps to promote better performance of borohydride SSEs are sketched out, which will pave the way for their further development in the field of energy stora...

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The development of simple, rapid-response sensors for water detection in organic solvents is highly desirable in the chemical industry. Here we demonstrate a unique luminescence water sensor based on a dual-emitting europium-organic framework (Eu-MOF), which is assembled from a purposely selected 2-aminoterephthalic acid ligand with responsive fluorescence inherent in its intramolecular charge transfer (ICT) process. This ICT process can be rapidly switched-on in the presence of water owing to its ability to boost and stabilize the ICT state. In contrast, the Eu3+ emission within the framework is insensitive to water and can serve as a reference, thus enabling highly sensitive water detection in a turn-on and ratiometric way. In addition, the significant ratiometric luminescence response induced by water makes Eu-MOF undergo a distinct change of emitting color from red to blue, which is favorable for visual analysis with the naked eye. Sensitive determination of water content (0.05–10% v/v) in various organic solvents is achieved in multiple readouts including ratiometric emission intensity, emission color, or the Commission Internationale de l’Eclairage (CIE) chromaticity coordinate. The present Eu-MOF sensor featuring high sensitivity and reusability, self-calibration, simple fabrication and operation, and capability for real-time and in situ detection is expected to have practical applications in water analysis for industrial processes.

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