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The hydrogen-bonding networks of water have strong intra- and intermolecular vibrational coupling which influences the energy dissipation and proton transfer in water. Disentangling and quantitative characterization of different coupling effects in water at a single-molecular level still remains a great challenge. Using tip-enhanced inelastic electron tunneling spectroscopy (IETS) based on low-temperature scanning tunneling microscopy, we report the direct quantitative assessment of the intermolecular coupling constants of the OH-stretch vibrational bands of an isolated water tetramer adsorbed on a Au(111)-supported NaCl(001) bilayer film. This is achieved by distinguishing various coupled modes of the H-bonded O–H stretching vibrations through tip-height dependent IET spectra. In contrast, such vibrational coupling is negligible in the half-deuterated water tetramer owing to the large energy mismatch between the OH and OD stretching modes. Not only do these findings advance our understanding on the effects of local environment on the intermolecular vibrational coupling in water, but also open up a new route for vibrational spectroscopic studies of extended H-bonded network at the single-molecular level. [ABSTRACT FROM AUTHOR]

The rechargeable aqueous Zn||MnO2 chemistry has been extensively explored, but its electrochemical reaction mechanisms, especially in the context of MnO2/Mn2+ conversion and Zn2+/H+ intercalation chemistry, remain not fully understood. Here, we designed an amphiphilic hydrogel electrolyte, which distinguished the MnO2/Mn2+ conversion, Zn2+ intercalation, and H+ intercalation and conversion processes at three distinct discharge plateaus of an aqueous Zn||MnO2 battery. The amphiphilic hydrogel electrolyte is featured with an extended electrochemical stability window up to 3.0 V, high ionic conductivity, Zn2+‐selective ion tunnels, and hydrophobic associations with cathode materials. This specifically designed electrolyte allows the MnO2/Mn2+ conversion reaction at a discharge plateau of 1.75 V. More interesting, the discharge plateaus of ~1.33 V, previously assigned as the co‐intercalation of Zn2+ and H+ ions in the MnO2 cathode, are specified as the exclusive intercalation of Zn2+ ions, leading to an ultra‐flat voltage plateau. Furthermore, with a distinct three‐step electrochemical energy storage process, a high areal capacity of 1.8 mAh cm−2 and high specific energy of 0.858 Wh cm−2, even at a low MnO2 loading mass of 0.5 mg cm−2 are achieved. To our knowledge, this is the first report to fully distinguish different mechanisms at different potentials in aqueous Zn||MnO2 batteries. [ABSTRACT FROM AUTHOR]

The rechargeable aqueous Zn||MnO2 chemistry has been extensively explored, but its electrochemical reaction mechanisms, especially in the context of MnO2/Mn2+ conversion and Zn2+/H+ intercalation chemistry, remain not fully understood. Here, we designed an amphiphilic hydrogel electrolyte, which distinguished the MnO2/Mn2+ conversion, Zn2+ intercalation, and H+ intercalation and conversion processes at three distinct discharge plateaus of an aqueous Zn||MnO2 battery. The amphiphilic hydrogel electrolyte is featured with an extended electrochemical stability window up to 3.0 V, high ionic conductivity, Zn2+‐selective ion tunnels, and hydrophobic associations with cathode materials. This specifically designed electrolyte allows the MnO2/Mn2+ conversion reaction at a discharge plateau of 1.75 V. More interesting, the discharge plateaus of ~1.33 V, previously assigned as the co‐intercalation of Zn2+ and H+ ions in the MnO2 cathode, are specified as the exclusive intercalation of Zn2+ ions, leading to an ultra‐flat voltage plateau. Furthermore, with a distinct three‐step electrochemical energy storage process, a high areal capacity of 1.8 mAh cm−2 and high specific energy of 0.858 Wh cm−2, even at a low MnO2 loading mass of 0.5 mg cm−2 are achieved. To our knowledge, this is the first report to fully distinguish different mechanisms at different potentials in aqueous Zn||MnO2 batteries. [ABSTRACT FROM AUTHOR]

Relevant to broad applied fields and natural processes, interfacial ionic hydrates have been widely studied by using ultrahigh-resolution atomic force microscopy (AFM). However, the complex relationship between the AFM signal and the investigated system makes it difficult to determine the atomic structure of such a complex system from AFM images alone. Using machine learning, we achieved precise identification of the atomic structures of interfacial water/ionic hydrates based on AFM images, including the position of each atom and the orientations of water molecules. Furthermore, it was found that structure prediction of ionic hydrates can be achieved cost-effectively by transfer learning using neural network trained with easily available interfacial water data. Thus, this work provides an efficient and economical methodology that not only opens up avenues to determine atomic structures of more complex systems from AFM images, but may also help to interpret other scientific studies involving sophisticated experimental results. [ABSTRACT FROM AUTHOR]

• Ionic and electronic conductivity of LMR were improved simultaneously. • Atomic pins-assisted integrated surface reconstruction stabilized interphase. • The degradation factors at different current rates were distinguished. • The mechanism of increasing conductivity was elucidated. • High capacity and stability at high rate were obtained. Li- and Mn-rich oxides (LMR) have emerged as promising cathode materials for next-generation Li-ion batteries due to their cost effectiveness, impressive capacity, and high energy density. However, the poor electrochemical kinetics and structural instability in hostile interface environments have result in continuous voltage/capacity decay and undesirable rate performance, impeding the large-scale commercial application of LMR materials. In this study, we introduce an atomic pins-assisted integrated surface reconstruction (AISR) strategy to address the interfacial degradation and instability issues. Utilizing the bidirectional diffusion effect of the aluminum-containing intermediate layer during the heat treatment process, we employ aluminum atoms as bridging centers to in situ construct a composite interface structure. This approach capitalizes on the element diffusion reaction and anchoring effect to achieve multifunctional modification through the Al-based ionic conductor network constructing and near-surface Al doping for LMR material. Intriguingly multiple kinetic investigations and calculations reveal that the epitaxial ionic conductor layer suppresses interfacial side reactions, enhances ionic conductivity, and improves electronic conductivity by regulating cationic/anionic redox activity through Al surface doping.Impressively, the modified electrodes exhibited an increased reversible capacity at both 0.1C/5C rates (0.1C, 2 ∼ 4.8 V, from 264.2 mAh∙g−1 to 274 mAh∙g−1; 5C, 2 ∼ 4.6 V, from 145.5 mAh∙g−1 to 197.9 mAh∙g−1) and improved capacity retention after 250 cycles at 1C/5C rates (2 ∼ 4.6 V: 1C, from 69.46% to 81.92%; 5C from 57.73% to 81.35%). We systematically summarized the rate-dependent failure mechanism and the corresponding integrated interface reconstruction principle. These key findings offer valuable insights for the development of high-energy–density and long-life lithium-ion batteries in commercial applications. [ABSTRACT FROM AUTHOR]