Wen Shi

Manganese‐based oxide is arguably one of the most well‐studied cathode materials for zinc‐ion battery (ZIB) due to its wide oxidation states, cost‐effectiveness, and matured synthesis process. As a result, there are numerous reports that show significant strides in the progress of Mn‐based oxides as ZIB cathode. However, ironically, due to the sheer number of Mn‐based oxides that have been published in recent years, there remain certain contemplations with regards to the electrochemical performance of each type of Mn‐based oxides and their performance comparison among various Mn polymorphs and oxidation states. Thus, to provide a clearer indication of the development of Mn‐based oxides, the recent progress in Mn‐based oxides as ZIB cathode was summarized systematically in this Review. More specifically, (1) the classification of Mn‐based oxides based on the oxidation states (i. e., MnO₂, Mn₃O₄, Mn₂O₃, and MnO), (2) their respective polymorphs (i. e., α‐MnO₂ and δ‐MnO₂) as ZIB cathode, (3) the modification strategies commonly employed to enhance the performance, and (4) the effects of these modification strategies on the performance enhancement were reviewed. Lastly, perspectives and outlook of Mn‐based oxides as ZIB cathode were discussed at the end of this Review.

Vanadium-based oxide is widely investigated as a zinc ion battery (ZIB) cathode due to its ability to react reversibly with Zn²⁺. Despite its successful demonstration, modification with simple molecules has shown some promise in enhancing the performance of ZIBs. Thus, this presents an immense opportunity to explore simple molecules that can dramatically improve the electrochemical performance of electrodes. Thus, the effect of CO₂ modification is studied in this work by decomposing oxalic acid within a hydrated V₆O₁₃ framework. Based on the collective results, the presence of CO₂ drastically lowers the relative energy of Zn²⁺ diffusion through the pathways by forming weak electrostatic interactions between O_CO2 and Zn²⁺. This leads to an enlarged diffusion contribution, which consequently results in enhanced stability and better rate performance. The as-synthesized CO₂–V₆O₁₃ electrode delivers one of the highest specific capacities reported for vanadium-based oxides of ca. 471 mAh g^–1. Furthermore, an excellent cyclic stability of 80% capacity retention after 4000 cycles at 2 A g^–1 is recorded for CO₂–V₆O₁₃, which suggests the importance of simple molecules in the material framework toward the enhancement of ZIB cathode performance.

A novel hydrophilic and self-assemble functional methoxy polyethylene oxide propyl trimethoxysilane was synthesized by hydrosilylation reaction using methoxy polyethylene oxide monoallyl ether and trimethoxysilane. The self-assembled layer of methoxy polyethylene oxide propyl trimethoxysilane was prepared by immersing hydroxylate silicon substrate in silane solution. The structure, morphology and hydrophilicity of self-assembled layer were characterized by means of X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and water contact angle method. The results show that methoxy polyethylene oxide propyl trimethoxysilane can self-assemble on the surface of hydroxylate silicon substrate. At concentration of 0.80 g/100 mL and the self-assembling time of 60 minutes, the self-assembled layer of methoxy polyethylene oxide propyl trimethoxysilane of average molecular weight of 682 shows a brush-like structure with each brush column size of 10~15 nm in diameter and 5~8 nm in height. The correspondence of the columns height with the average length of the silane molecules suggests that the layer obtained is monolayer and the brush columns are constituted by extended PEO molecular chain units in the silane. The distribution of columns is uniform and the root-mean-square（RMS） roughness of self-assembled monolayer is 0.98 nm. Water contact angle of the monolayer is 7.4°. A super-hydrophilic surface is obtained.