Search Results (247)

Lithium-ion batteries (LIBs) typically operate within a temperature range of 20–50 °C, depending on the chemical composition and application of the battery. Overheating may lead to degradation and thermal runaway, while overcooling may cause lithium plating and internal short circuits. Absorbing heat during the melting of phase-change materials (PCMs) has become an attractive passive thermal management strategy. However, organic PCMs such as paraffin are flammable, and most strategies for improving their inherently low thermal conductivity, such as adding carbon fillers and engineering porous scaffolds, sacrifice latent heat, electrical safety, or cost. Flame retardants achieve flame retardancy at the cost of 15–25% of latent heat, while inorganic PCMs eliminate flammability but introduce undercooling and corrosion. This study synthesizes the PCM–battery thermal management system (BTMS) literature with this safety–performance tension as its organizing principle, covering composite PCM strategies for thermal enhancement, flame-retardant approaches and thermal runaway mitigation, hybrid PCM–active cooling systems, and emerging directions that transcend rather than manage the trade-off. It also identifies the gaps between laboratory demonstration and commercial deployment: durability data measured in hundreds rather than thousands of cycles, absent standardized testing protocols, and manufacturing routes that have not left the university laboratory. Full article

Sulfide solid electrolytes (SSEs) are promising for all-solid-state lithium batteries (ASSLBs) due to their high ionic conductivity, mechanical deformability, and interfacial compatibility. However, SSE interfaces with anodes, cathodes, conductive additives, and current collectors are unstable, triggering safety failures like capacity degradation, internal resistance build-up, thermal runaway, and short circuits. This review summarizes recent progress on interface-induced safety failure mechanisms in sulfide-based ASSLBs, focusing on interface types, failure mechanisms, and thermal/mechanical degradation under multi-field coupling. We survey interface modification strategies and highlight advanced characterization techniques for probing interfacial phenomena. Key challenges and future research directions are discussed. Integrating recent findings, we identify interfacial instability as the primary bottleneck governing safety failures, providing a theoretical and technical framework for rational interface design, performance optimization, and safety enhancement. Throughout this review, we use SSE as the standard abbreviation for sulfide solid electrolytes. Full article

The increasing penetration of inverter-based renewable energy resources is reshaping transmission-line fault characteristics and weakening protection criteria designed for synchronous-generator-dominated grids. This paper proposes an internal-fault identification scheme based on voltage–current coupling characteristic curves (UICs) constructed from voltage and current measurements at both line terminals. Geometric descriptors of the UIC are used to build an ellipsoidal feature space representing normal operating conditions and external faults. Internal faults are identified from the normalized distance between the online feature vector and this space. A local voltage-transient startup criterion is also introduced, and current-transformer (CT) saturation correction is incorporated to reduce distortion in the measured currents. PSCAD simulations under different fault locations, transition resistances, fault types, noise levels, and CT-saturation conditions show that the proposed scheme distinguishes internal faults from external faults and normal operation reliably. Because the criterion depends on line-side coupling features rather than the short-circuit output of a specific power source, it is suitable for protection applications in renewable energy systems with grid-forming inverters. Full article

Hydraulic short-circuit (HSC) operation is an important approach to enhancing the operational flexibility of pumped-storage power plants (PSPPs). However, under this new operating mode, the flow characteristics in the bifurcated pipe deteriorate significantly, posing a threat to the efficiency of the piping system and potentially affecting the inflow conditions for the turbine. In this study, six improved bifurcated pipe models were designed, and their internal flows under pumping, generating, and HSC modes were numerically simulated. Entropy production theory and vortex identification method were employed for flow field analysis. The results show that local modifications confined to the bifurcation are insufficient to simultaneously improve energy characteristics across different modes. In contrast, the bypass pipe enables early flow diversion, weakening the original high-dissipation regions while introducing controllable additional losses. M6 achieves an average energy loss reduction of 47.85% in the mid-to-high flow split ratio range (FSR > 0.3). A strong correlation is observed between vortex suppression and energy loss reduction: the bypass pipe substantially shortens the main vortex length at the inlet section of the generating branch, while simultaneously inducing new shear vortices at the junction; adjustment of its installation position is expected to further shorten their extension, thereby ensuring the normal operation of the turbine. This study provides a new technical pathway for extending the operating range of HSC operation and contributes to enhancing the grid-regulation capability of PSPPs. Full article

To address the issues of excessive fault current, insufficient voltage support, and frequency oscillations in grid-forming converters during power grid short-circuit faults, this paper establishes a fault ride-through test model based on the principle of impedance voltage division and analyzes the fault transient characteristics of a virtual synchronous generator (VSG). A fault-voltage support strategy integrating reactive power injection and internal electromotive force (EMF) regulation, together with an active power regulation method based on current-limiting constraints, is proposed. An adaptive inertia-damping mechanism is introduced into the control loop, which dynamically regulates the virtual inertia and virtual damping coefficients to suppress frequency fluctuations during fault engagement and clearance. The rationality of the system parameter configuration is verified through impedance modeling, and experimental validation is conducted using the RT-LAB hardware-in-the-loop (HIL) platform. The results demonstrate that the proposed multi-objective coordinated control strategy enables the converter to remain connected to the grid during faults. The steady-state fault current meets the limit requirements, the frequency response is stable, and reactive power support complies with the national standard. This study provides theoretical support for fault ride-through of grid-forming converters in power systems with a high proportion of power electronics. Full article

Structurally integrated lithium-ion batteries (LIBs) in bionic underwater vehicles face increasingly complex internal short circuit (ISC) risks under mechanical abuse. In this study, a three-dimensional bidirectional mechanical–electrical–thermal coupling model is established to reconstruct the evolution from structural damage to ISC triggering in cylindrical LIBs under indentation conditions. A constitutive inversion method incorporating load, contact area, and volume evolution is proposed to calibrate the jellyroll stress–strain response for different indenter diameters. An ISC criterion based on separator thickness is then introduced, and local short-circuit paths are realized through dynamic topology updates of the distributed equivalent circuit model network. The calibrated model reproduced the experimental load response, voltage decay, temperature rise, and damage morphology. The systematic investigation into ISC behavior shows that indenter diameter governs competition among local shear, local bending, and global compression, while loading position determines structural constraint and boundary effects. Rather than corresponding to the minimum ISC load, the most hazardous condition (4 mm indenter diameter and 18 mm loading position) exists where local stress concentration and weakened structural constraints jointly promote rapid separator failure, shortening the ISC triggering time to 79.2 s. These findings provide guidance for battery safety assessment and structural protection design in underwater vehicles. Full article

To address the limited pumping-mode flexibility of fixed-speed pumped-storage units, this paper presents a simulation case study of a one-pipe–two-unit parallel ternary system developed in OpenModelica and coupled with Python 3.7. The study examines pure charging and generation, hydraulic short-circuit (HSC) charging, and the PID control-activation transient at nominal speed. A 50 MW benchmark reproduces published pump and turbine shaft powers to within approximately 0.5%, while the system-efficiency difference is 0.14 percentage points, supporting implementation consistency; no plant-measurement validation is claimed. Dual-pump operation reduces the charging time by approximately 44% relative to single-pump operation but lowers efficiency, whereas dual-turbine operation is slightly more efficient because of improved per-unit flow matching. Across the full-cycle HSC sweep, average efficiency increases from 38.6% at 40 MW to 74.1% at 90 MW as internal recirculation decreases. In the PID sensitivity screen, the proportional gain k has the largest effect on the response, a small integral time T_i amplifies sensitivity to k and can increase overshoot or hydraulic loading, and the derivative coefficient w_d has only a minor effect within the tested range. The numerical bounds are specific to the selected characteristic maps, reservoir, and waterway; the results are intended as retrofit-screening guidance rather than universal design limits. Full article

A polyurea-coated carbon fiber reinforced plastic (CFRP) laminated structure is designed to enhance the impact resistance of lithium-ion batteries against ground impact. This paper presents a numerical simulation to investigate the influence of a polyurea-coated CFRP battery pack bottom plate on mitigating battery damage under ground impact conditions. A novel three-dimensional finite element model of the polyurea-coated CFRP laminate, incorporating a hyper-viscoelastic material model for the polyurea coating and an orthotropic model for the CFRP, is established to analyze the impact response and damage behavior of the laminate. The simulated impact peak force, energy absorption, and maximum crack length of the polyurea-coated CFRP laminate are all within 5% of the experimental results. Based on this validated three-dimensional model, a new battery pack simulation model is developed. The battery module model innovatively adopts a hybrid approach that combines homogenized battery module models and detailed battery module models, enabling accurate simulation of localized cell damage and failure during collisions while significantly improving computational efficiency. The punching process after perforation of the polyurea-coated CFRP laminate, the subsequent crack propagation of the plate, and the local deformation modes of individual cells are clearly predicted by the global model. Battery shortening is recorded as an important indicator of internal short circuits and potential thermal runaway. A parametric study is carried out, and several underlying rules are revealed: the front coating method leads to a greater reduction in battery damage, and the stiffness–toughness interplay between the polyurea coating and the carbon fiber composite is identified as a critical factor governing battery damage. This study provides important insights for the design of protective structures for battery packs against ground impact. Full article

Although incremental capacity (IC) curve analysis is promising for early internal short circuit (ISC) detection, its diagnostic accuracy degrades significantly across a wide resistance range, especially for low-resistance events dominated by leakage currents. To overcome this limitation, we propose a threshold-adaptive ISC diagnostic framework that dynamically integrates quantitative resistance calculation (for high resistance, R ≥ 100 Ω) with Gaussian process regression (GPR)-based leakage current analysis (for low resistance, R < 100 Ω). Validated on 20 Ah LiFePO₄ batteries, this approach achieves <6% error for 100–300 Ω and <8% error for <100 Ω (after GPR correction), demonstrating robust, implementation-ready solutions for real-world battery safety monitoring. Full article

Shipboard lithium-ion battery systems experience continuous mechanical vibration, yet model-based and data-driven internal short-circuit (ISC) detectors have not been compared under such conditions. We present, to our knowledge, the first unified vibration-aware ISC benchmark: a model-based Extended Kalman Filter (EKF) $\Delta \mathrm{SOC}$ rule and three convolutional detectors—ModernTCN, LITE, and NPU-Conv2D—are evaluated on a simulated NCR18650PF module under quiescent, MIL-STD-810H-derived, and head-sea vibration, with vibration coupled to cell resistance through a phenomenological assumption $\Delta R=k_R\left|a\right|$. The EKF observes the terminal voltage alone, whereas the data-driven detectors additionally observe cell temperature, so the comparison couples detector class with input observability. Under this assumed envelope and the swept coupling range, the dual-channel data-driven configurations pass $135/135$ deadline-scored outcomes against $129/135$ for the EKF, with zero pre-onset false alarms versus 15, and their advantage lies in detection-delay dispersion rather than in mean latency. Deployed on an STM32N6 microcontroller, the INT8 NPU-Conv2D completes one inference in $0.752$ ms, $179\times$ lower latency than the EKF firmware. Calibration-free robustness emerges as the practical advantage of the evaluated dual-channel detectors. Full article

The large-scale integration of inverter-interfaced renewable generation has made the steady-state short-circuit current of renewable energy stations increasingly important for setting protections, planning, and fault analysis. Traditional single-unit multiplication methods are computationally efficient but often ignore the effects of internal electrical distance and active power output dispersion among generation units, which can lead to non-negligible errors at the station level. To address this issue, this paper proposes an improved single-unit multiplication method and a corresponding dimension-reduction framework for centralized renewable energy stations considering short-circuit current fitting characteristics. A unified three-segment positive-sequence current control model is first adopted to represent the low-voltage ride-through behavior of photovoltaic (PV), direct-drive wind turbine, and battery energy storage system (BESS) stations. The upper and lower voltage breakpoints are selected as 0.9 p.u. and 0.2 p.u., respectively, and the linear support coefficient was determined as 1.5 according to Chinese national standards. On this basis, the effects of electrical distance and active power output dispersion on the calculation error of the traditional single-unit multiplication method are analyzed. A grouping criterion based on the average access-point voltage and critical active power is then established, and the resulting two-group equivalent method is used to estimate the total short-circuit current of renewable energy stations. Electromagnetic transient simulations in PSCAD are conducted for PV, direct-drive wind, and BESS stations. The results show that, compared with the traditional single-unit multiplication method, the proposed method more accurately captures the steady-state short-circuit current characteristics under different voltage dips and output-dispersion conditions while retaining high engineering practicality. Full article

Driven by the increasing energy density of battery energy storage systems, immersion cooling (IC) has emerged as a promising approach for mitigating thermal runaway (TR) hazards. In this study, overcharge-induced TR tests were conducted on commercial 314 Ah lithium iron phosphate batteries in an accelerating rate calorimeter to compare their thermal, pressure, mass loss, and gas venting responses under air cooling (AC) and static ester-based immersion cooling. For the two cells tested, internal short circuit onset occurred at 1150 s under AC and 1377 s under IC, while TR was triggered at 1232 and 1404 s, respectively. The peak surface temperature decreased from 422.4 °C under AC to 302.4 °C under IC, and the maximum surface temperature difference was reduced by approximately 31%. The maximum chamber pressure rise rate decreased from 3.12 to 1.68 kPa/s, although a higher late-stage cumulative pressure was observed under IC within the sealed ARC chamber. Battery mass loss decreased from 1014.2 g (18.27%) under AC to 845.2 g (15.24%) under IC. In addition, the CO₂ fraction in the post-cooling gas mixture increased from 30.4% to 38.4%, while the H₂ fraction decreased from 43.6% to 36.9%. Based on the modified Le Chatelier calculation, the estimated lower explosive limit increased from 6.16% to 7.18%, suggesting lower composition-based ignitability under the adopted assumptions. Overall, the tested static ester-based immersion cooling configuration delayed TR evolution, reduced peak thermal response and mass loss, and moderated the transient pressure rise under the present experimental conditions. These findings provide experimental reference data for the thermal-safety design of large-capacity battery energy storage systems. Full article

Due to the low inertia and small internal resistance of the DC line, the short-circuit fault is more harmful to the DC microgrid than the AC microgrid. Therefore, rapid and accurate detection of faults in DC microgrids plays an important role in ensuring the stable operation of DC microgrids. In this paper, the residual generator is designed based on the state observer, and the fault diagnosis of the DC microgrid is achieved by analyzing and processing the residual signal. Firstly, a mathematical model is established for a single line, and the corresponding residual generator is designed by using the unknown input observer to achieve the fault detection of a single key protection line. Secondly, considering the high cost of fault detection for each line alone, a residual generator is established for the entire DC microgrid to achieve fault detection of the entire DC microgrid, which effectively reduces the cost of fault detection. Finally, the radial DC microgrid and the ring DC microgrid are simulated and verified respectively to ensure that the designed fault diagnosis method is applicable to both topologies. Full article

As the global automotive industry is transitioning toward sustainable development, new energy vehicles (NEVs) have experienced rapid global growth due to their environmental friendliness and high efficiency. Global sales of NEVs are projected to reach 50 million units by 2030. Nevertheless, safety incidents caused by impacts on traction batteries remain a major factor restricting the development of NEVs. Prismatic batteries, which account for over 90% of the traction battery market owing to their high energy density and structural robustness, nevertheless continue to face significant safety challenges under mechanical loading conditions. Typical failure modes involve structural damage induced by external compressive forces during severe vehicular collisions, which can subsequently result in the tearing of internal electrode layers and rupture of the separator, thereby initiating internal short circuits and leading to severe incidents. Accordingly, this research focuses on the mechanism of structural damage transmission for prismatic lithium-ion batteries under compression conditions. By integrating a refined mechanical model, it further elucidates the structural failure mechanisms and conducts a microscopic analysis of the damaged battery structure to investigate the effects of varying damage levels on battery safety performance, providing significant guidance for the safety and reliability of new energy vehicles. Full article

To date, lithium–ion batteries (LIBs) are considered one of the most promising and market-leading energy storage systems due to their high theoretical capacity and energy density. However, poor thermal and cyclic stability, low electrolyte uptake, and the possibility for frequent short circuits of typical separators and evolution of several gases during long cycle operation pose several problems for LIBs. Metal-organic frameworks (MOFs) have attracted widespread interest as a promising material for improving the cycle stability and safety of rechargeable batteries due to their inherent surface and structural properties such as high specific surface area, high porosity, and ionic conductivity. In this work, the aim is to provide detailed descriptions of the synthesis routes and parameters for obtaining various MOFs such as Zr-MOF-808 and Ni-MOF-74 nanoparticles and the fabrication of those MOF-integrated separators. To optimize the crystallinity, morphological and compositional characteristics, and several material characterizations such as XRD, SEM, and EDX have been applied. Afterwards, the synthesized MOF-integrated glass fiber (GF) separators have been developed for lithium–ion battery (LIB) applications. To investigate the electrochemical performance and the effect of MOF integration into the separators, electrochemical studies in the form of galvanostatic charge–discharge (GCD), electrochemical impedance spectroscopy (EIS) have been evaluated by preparing CR2032-type half-coin cells. This MOFs-integrated GF-separators and synthesized LiNi_0.6Mn_0.2Co_0.2O₂ (NMC622) cathode materials-based coin cell LIB exhibited higher cycle stability than bare GF-separator based LIB. This novel approach and extensive research suggest that development of MOF-integrated separators could significantly improve cycle stability by reducing the internal cell degradation for next generation energy storage devices. Full article