Yuqi Huang

Batteries have been widely applied in various fields due to the advantages such as high energy density, long service life and so on, whereas they are accompanied by frequent thermal runaway incidents and this is a worldwide challenge. However, non‐invasive warning methods capable of providing early‐stage alerts are missing, especially for non‐planar sidewall pressure monitoring of cylindrical batteries. Here, a smart pressure sensor based on shape memory sensing composite is introduced, which enables conformal contact with cylindrical batteries and can continuously monitor the lateral pressure caused by volume expansion during charging‐discharging. Moreover, the assembly process, designed based on COMSOL simulations, ensures conformal contact between the sensor and the test interface, effectively preventing uneven stress distribution during the assembly of the multi‐layer structure. This smart sensor features impressive stability and recoverability, a broad pressure detection range (50–2340 kPa), excellent hysteresis error (1.17%), high linearity ( R ² = 0.99) and a maximum deviation of 1.56% over 20000 cycles. It can monitor radial pressure changes, achieving a warning time ratio of 80%, 84%, 86%, and 79% in thermal runaway tests on 18650, 21700 ternary lithium‐ion batteries, 32700 LiFePO ₄ battery and 18650 sodium‐ion battery, respectively. Timely measures after warning can prevent thermal runaway.

Internal short circuits (ISCs) pose a significant safety threat to lithium-ion batteries (LIBs), and precise diagnosis relies on in-depth understandings of ISC mechanisms and characteristics. This study systematically investigated the electrochemical impedance evolution process triggered by different degrees and modes of ISCs in NCM/graphite semi-solid lithium-ion batteries. We designed a controllable introduction of ISCs with variable intrusion types and penetration depths, and based on equivalent ISC current, classified ISCs into three severity levels: soft, moderate and hard. Comprehensive assessments, including electrical-thermal responses, self-discharge rates, Coulombic efficiency (CE), incremental capacity analysis (ICA), and disassembly detection, were conducted on ISC LIBs. Using Electrochemical Impedance Spectroscopy (EIS) testing and Distribution of Relaxation Times (DRT) analysis techniques, we conducted a detailed characterization of the impedance characteristics of ISC LIBs. We found that as the degree of ISC deepens, the charge transfer impedance of LIBs decreases significantly, while the polarization resistance of the liquid phase transport process increases. However, the external short circuit (ESC) of the comparative verification does not exhibit these characteristics. The findings and analytical insights derived from this research offer a viable pathway for developing effective fault diagnosis schemes for LIB internal short circuits.

Gel-based propellants have gained significant attention in aerospace and propulsion applications, yet the atomization characteristics of gel-based propellants with shear-thinning behavior are still lacking understanding. In this study, the primary atomization behavior of shear-thinning fluid jets is investigated using a three-dimensional coupled Volume of Fluid and Lagrangian Particle Tracking model integrated with direct numerical simulation. A modified power-law model is employed to accurately capture the shear-dependent viscosity, and the numerical approach is rigorously validated. The results show that shear-thinning jets exhibit earlier onset and faster radial growth of surface instabilities compared with Newtonian jets. During the early stage, a viscosity–pressure positive-feedback mechanism accelerates wave amplification, while downstream axial curvature effects dominate and suppress further growth, consistent with the observed reduction in cumulative deviation beyond ≈11D. Interface steepening enhances aerodynamic shear and induces multilayer recirculation near surface waves, promoting the formation of internal voids within the liquid column. With increasing consistency index k and decreasing power-law index n, the maximum cumulative deviation rises from 2.77D to 4.14D, while the length of the positive-feedback region decreases from 11.0D to 9.46D, indicating that stronger shear-thinning effects accelerate the amplification of instability waves while confining their axial growth. These findings provide new insights into the nonlinear instability dynamics and interfacial evolution during the breakup of shear-thinning jets and establish a theoretical foundation for optimizing fuel injection systems utilizing rheologically complex or gel-based propellants.