This paper presents a numerical scheme to predict the milling stability based on the integral equation and numerical integration formulas. First, the milling dynamics taking the regenerative effect into account is represented in the form of integral equation. Then, the tooth passing period is precisely divided into the free vibration phase during which the analytical solution is available and the forced vibration phase during which an approximate solution is needed. To obtain the numerical solution of the integral equation during the forced vibration phase, the time interval of interest is equally discretized. Over each small time interval, Newton-Cotes integration formulas or Gauss integration formulas are employed to approximate the integral term in the integral equation. After establishing the state transition matrix of the system in one period, the milling stability is predicted by using Floquet theory. The benchmark examples are utilized to verify the proposed approach. The results demonstrate that it is highly efficient and accurate.

Lithium‐ion batteries are the most commercially successful electrochemical devices, extensively used in intelligent electronics, electric vehicles, grid energy storages, etc. However, there still needs to be further improvement of their performance such as in energy density, cyclability, rate capability, and safety. To do so, it is necessary to understand the detailed structural evolution progress inside the battery. Many advanced imaging techniques have been developed to directly monitor the status and get some key information inside the battery. For advanced imaging techniques, superhigh resolution, fully informative function, nondestruction of the sample, and in situ observation are required. This review introduces and discusses some recent important progress on a variety of advanced imaging techniques for battery research. These imaging techniques have enabled the visualization of sub‐micrometer level chemical valence distribution, evolution of solid‐electrolyte interface, Li dendrite growth, and trace amount of gassing, etc., which greatly promote the development of rechargeable batteries. Of particular note, a new ultrasonic imaging technique has been recently developed to monitor gas generation, the electrolyte wetting process, and the state of charge in the battery. Finally, a perspective is given on some future developments in the imaging techniques for Li‐ion batteries and other rechargeable batteries.

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The interface is a critical factor of electrochemical performance for all‐solid‐state batteries (ASSBs). Comprehending the composition, structure, morphology, and their evolution in the interface during charge/discharge cycling is greatly important for the development and practical application of ASSBs. The characterization techniques are very crucial and powerful for investigating the interface properties of ASSBs. This review briefly describes how the interface is generated in ASSBs, and then emphatically summarizes some important advanced techniques used to characterize the interface in ASSBs. The principle, advantage, and application of the techniques in the interface investigation are systematically discussed. This review provides fundamental insights and perspectives for developing the characterization techniques to deeply understand the interfacial behaviors of ASSBs, which is valuable for accelerating the commercialization of ASSBs used in electronic devices, electric vehicles, and large‐scale energy storage.

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