LiCoO2, which was first proposed as a cathode in 1980 by Prof. John B. Goodenough, is still one of the most popular commercial cathodes for lithium‐ion batteries. Tremendous efforts have been invested in increasing the capacity of LiCoO2 by charging to high voltage. However, a series of issues, such as structural instability and dramatic side reactions with electrolytes, can emerge as cut‐off voltage above 4.5 V (vs Li/Li+). Here, a surface modification strategy with a multilayer structure is provided, involving a Zn‐rich surface coating layer, rock‐salt phase buffer layer and surface gradient Al doping layer, to overcome the detrimental issues and achieve stable cycling of LiCoO2 at 4.6 V. The complete coating of the modification layer restrains the interfacial side reactions with electrolyte and inhibits the impedance growth. The phenomenon of quasi‐epitaxial growth demonstrates that the multilayer structure significantly reduces the lattice mismatch between host LiCoO2 and surface coating layer and enhances the stability of the Zn‐rich outside layer, which promote the long‐term effectiveness of the modification. Furthermore, the disordered rock‐salt phase layer and Al surface doping also enhance the structural stability. All of these synergistically lead to the stable cycling of LiCoO2 at 4.6 V with a capacity retention of 65.7% after 500 cycles.

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Noble metal nanoenzymes such as Pt, Au, Pd, etc. exhibit magnificent activity. However, due to the scarce reserves and expensive prices of precious metals, it is essential to investigate their enzyme-like activity and explore the possibility of their reuse. In this work, the oxidase-like activity and reusability of several Pt nanoparticles with different morphologies were detected. We compared the Pt nanoparticles (NPs) with a size of about 30 nm self-assembled by 5 nm Pt nanoparticles and Pt nanoparticles (Pt-0 HCl) with a diameter of about 5 nm, and found that their Michaelis−Menten constants (Km) were close and their initial performance similar, but the Pt NPs had better reusability. This was probably attributed to the stacked structure of Pt NPs, which was conducive to the substance transport and sufficient contact. At the same time, it was found that the size, dispersion, and organic substances adsorbed on the surface of Pt nanoparticles would have a significant impact on their reusability. A colorimetric detection method was designed using the oxidase-like activity of Pt NPs to detect ascorbic acid in triplicate. The limits of detection were 131 ± 15, 144 ± 14, and 152 ± 9 nM, with little difference. This research not only showed that the morphology of the catalyst could be changed and its catalytic performance could be controlled by a simple liquid phase synthesis method, but also that it had great significance for the reuse of Pt nanoenzymes in the field of bioanalysis.