Despite the commercial success of lithium-ion batteries (LIBs), the risk of thermal runaway, which can lead to dangerous fires, has become more concerning as LIB usage increases. Research has focused on understanding the causes of thermal runaway and how to prevent or detect it. Additionally, novel thermal runaway-resistant materials are being researched, as are different methods of constructing LIBs that better isolate thermal runaway and prevent it from propagating. However, field firefighters are using hundreds of thousands of liters of water to control large runaway thermal emergencies, highlighting the need to merge research with practical observations. To study battery fire, this study utilized a temperature abuse method to increase LIB temperature and investigated whether thermal runaway can be suppressed by applying external cooling during heating. The batteries used were pouch-type ones and subjected to high states of charge (SOC), which primed the thermal runaway during battery temperature increase. A water spray method was then devised and tested to reduce battery temperature. Results showed that, without cooling, a thermal runaway fire occurred every time during the thermal abuse. However, external cooling successfully prevented thermal runaway. This observation shows that using water as a temperature reducer is more effective than using it as a fire suppressant, which can substantially improve battery performance and increase public safety.

Lithium-ion batteries (LIBs) are subject to mechanical abuse both in electric vehicles and consumer electronic applications when dropped, which can lead to capacity degradation even if the cells survive the impact. This study investigates the impact of mechanical damage on the electrochemical performance of LIBs, focusing on capacity retention and internal resistance changes. The batteries were subjected to dynamic mechanical impact using varying impact energies (3J, 5J, and 7J) while measuring internal resistance and capacity before and after the impact. Hybrid Pulse Power Characterization (HPPC) was employed to assess internal resistance and capacity degradation across multiple cycles. Our results demonstrate that even minor mechanical damage can cause significant performance decay, especially after several cycles. The study also reveals that the state of charge (SOC) prior to impact has a minimal effect on the survival rate of the cells but influences the extent of damage observed. Post-impact analysis using optical microscopy indicates structural damage, including separator tears and delamination, contributing to capacity fade. This work highlights the importance of considering intermediate mechanical damage in LIB safety and performance assessments.

Na ₃ V ₂ (PO ₄ ) ₂ F ₃ (NVPF) is a promising cathode material for sodium-ion batteries (SIBs) because of its structural robustness, high operating voltage, fast Na ⁺ transport, and stable electrochemical performance, and NVPF/hard carbon (HC) is well established as a high-rate chemistry. However, its full-cell thermal behavior remains insufficiently understood. Here, the exothermic behavior of NVPF/HC 18 650-format cylindrical cells is systematically investigated at 100%, 75%, and 50% state of charge (SOC) using accelerating rate calorimetry (ARC). NVPF/HC cells employing polyvinylidene fluoride (PVDF)- or carboxymethyl cellulose (CMC)-binder in HC anodes are further evaluated by long-term cycling and ARC and benchmarked against LiFePO ₄ (LFP)/graphite cells. NVPF/HC cells exhibit strong SOC-dependent thermal behavior, with higher SOC leading to earlier and more intense exothermic reactions. Both NVPF/HC and LFP/graphite cells retain ∼94% of their initial capacity after ∼200 cycles at 40 °C with limited growth in voltage polarization. Fresh and aged NVPF/HC cells exhibit similar thermal characteristics regardless of HC binder chemistry. After cycling, NVPF/HC and LFP/graphite cells exhibit distinct thermal behavior: while LFP/graphite cells show a slightly lower self-heating rate, NVPF/HC cells reach a much lower termination temperature (∼180 °C, beyond which no self-heating is detected) compared to ∼270 °C for LFP/graphite cells.

Mechanical abuse studies on lithium-ion batteries predominantly focus on localized, destructive loadings that trigger thermal runaway, leaving non-destructive planar dynamic stress and its long-term electrochemical degradation mechanisms under-explored. This study investigates the impact of dynamic, in-plane uniaxial compression on the long-term performance and degradation pathways of 1 Ah LCO-graphite pouch cells. Pre-aged cells (50 cycles) were subjected to flat-headed drop-weight impacts across a range of low energies (3, 5, 7, and 10 J) to isolate uniform planar compression while avoiding shear-driven separator rupture or internal short circuits. Post-impact cells were evaluated across 500 additional cycles using Hybrid Pulse Power Characterization, Incremental Capacity Analysis, and Scanning Electron Microscopy post-mortem imaging. Despite experiencing physical stress, dynamic impact did not compromise cell safety or alter long-term State of Health degradation trajectories. Instead, post-impact characterization revealed an immediate capacity rejuvenation coupled with an average reduction in ohmic resistance (R0) of 4.91±4.01 mΩ and a decrease in dynamic characteristic resistance (R1). ICA profiles demonstrated an increase in differential capacity peak heights post-impact, signaling a partial recovery of loss of active material. SEM analysis corroborated these findings, revealing inter-particular cracking of the solid electrolyte interphase on the anode and compaction of secondary cathode particles, which re-established conductive contacts in isolated electrode regions. These results demonstrate that uniform planar compression is not inherently catastrophic and can temporarily enhance performance by restoring active material networks, offering critical insights for second-life battery assessment and predictive mechanical abuse modeling.

The surge in lithium-ion battery (LIB) use, essential for mass-scale renewable energy storage, raises concerns about fire hazards. However, to date, there is a lack of industry-wide understanding of large-scale LIB fire propagation. This paper suggests a translational forensic approach to promote fire safety awareness and introduces the cellular automata (CA) model coupled with the Monte Carlo (MC) approach to address the complex fire propagation simulation within an energy storage system (ESS). The objective is to demonstrate that the CA-MC model can provide a flexible and scalable connection for all levels of battery fire studies. The numerical model is coupled with experimental tests which have been performed to establish the actual timing of fire propagation from a single source. Cellular automata simulation, conducted through hybrid modeling and an applied risk analysis approach to evaluate fire hazards associated with LIBs, offers crucial insights into potential risks. The results demonstrate that, with fire incident initiation at a probability of 0.1 (10%), 33% of batteries will burn, and at a probability of 0.6 (60%) and beyond, the entire battery module will face complete burndown. Achieving full combustion of the entire module will take only approximately 42 timesteps on average, indicating rapid fire propagation. The actual time for a complete fire to occur in the battery module has been estimated to be 304 s per timestep, or 3.5 h total. Using this example, it is shown that the CA-MC approach can be extended to many other aspects of battery fire studies and is ideal as a translational tool, spanning all domains of the LIB industry.