Cathode metallized polyester current collectors (PCC) show very consistent tolerance to nail penetration in 18650 and 21700 cell designs from one manufacturer. These designs achieve 233 Wh/kg (622 Wh/L) and 251 Wh/kg (684 Wh/L), respectively. In contrast, a 21700 achieving 272 Wh/kg and 724 Wh/L is consistently driven into TR with the same nail penetration test. Have we reached a specific energy limit for the PCCs?

The characteristics of internal short circuits (ISC) play a critical role in determining the thermal runaway behaviors and associated hazards of lithium-ion batteries (LIBs). However, due to safety concerns and limitations in operando characterization at high state-of-charges (SoCs), our fundamental understanding of stress-driven ISCs is still lacking. In this study, we employ combined post-mortem characterization and multiphysics modeling to clarify the evolution of ISC modes in LIBs with high SOCs. Results discover novel phenomena for ISC and reveal the underlying mechanism.

Rapidly heating a single Li-ion cell into thermal runaway (sec to <5 min) has recently been adopted as a test methodology into battery safety standards for EVs. This talk will go through the theory of the approach and show examples using different cell geometries and designs, as well as test objects (modules to full vehicles) that demonstrate this new robust and versatile abuse test methodology with minimal invasiveness.

Lithium battery safety remains the first and foremost concern, especially in hot summers. In this talk we shall introduce a reproducible and quantitative method to measure the shorting current, intracell temperature rise, and ensuing fires/smokes. We discover that lithium metal battery fires occur over an ultrashort time scale of 1-5 seconds, making pack-level safety measures virtually in vain. We also find the fuel to ignite the fires is not the electrolyte but the lithium metal, questioning the basic tenet that solid state batteries without flammable liquid electrolytes but with lithium metal are actually safer. 

Commercial Na-ion cells were tested for performance and safety at ESRI. Performance tests included two different charge/discharge rates and three different temperatures. Safety tests included overcharge, overdischarge, external short circuits, and heating tests. The results of the research studies will be presented.

This program will dive into the various changes affecting the built environment on batteries. From the proposed changes in the International Code Council Documents to the National Fire Protection Association.

Battery testing is important in the development and deployment of many of our devices, given the universal presence of batteries in modern life. Most people consider the features and quality of a product before purchasing it, but few are aware of the years of testing that happen before the product ever comes to market. Battery testing is a broad subject, but safety and reliability testing are two measures that are critical to evaluate a battery or battery pack.

Comprehensive review and assistance for industry and regulatory agencies in developing a standardized approach to the appropriate containment and mitigation of Li-ion batteries. First responders need to understand the risk, proper handling, and disposal of these devices. Appropriate transportation regulations and standards for damaged Li-ion devices need to be developed for large devices that do not meet special DOT permits, i.e., EV and ESS systems that have been damaged.

This talk details the risks associated with end-of -ife batteries and explores techniques for deactivating them when they reach the end of their useful life. Among these techniques, saltwater immersion shows promise, but it is hindered by slow deactivation and potential electrolyte release.

A summary of thermal runaway detection and consequence modeling from the UT Austin Fire Research Group. Failure detection has been performed using load cells, temperatures, gas sensors, and ultrasonic systems. Multiple models have been developed to understand the thermal runaway process and its consequences. Mathematical models are presented to predict cell thermal runaway and cell-to-cell runaway propagation. Reduced order models and computational fluid dynamics models are used to model gas release, fire, and explosion hazards. Multiple models span scales ranging from single cell to fire and explosion consequences on people and structures. 

Battery pads, composed of polyurethane, silicone, or aerogel, have been reengineered to prevent thermal runaway propagation between battery cells. We assessed the performance of these multifunctional foam pads through nail penetration testing of small battery modules, constructed with NMC cells and featuring these pads placed between the cells. This study covers not only pouch cells, but also prismatic cells, aiming to provide a comprehensive evaluation of thermal runaway mitigation requirements.

This work presents experimental data and analysis on the aerosol emission during Li-ion battery thermal runway. Both engine exhaust particle sizer (EPPS) and aerodynamic particle sizer (APS) are coupled with the accelerating rate calorimeter (ARC) to sample particles ranging from 5.6 nm to 560 nm, and from 0.5 to 20 microns respectively. Multimodal distribution of particles has been observed to shed light on fire safety, as well as environmental and inhalation hazards of particle emissions during thermal runaway,

International regulations raise the bar for battery pack safety by mandating that passengers shall have at least 5 minutes for safe egress from vehicles—from first cell failure to battery fire. As hot particles play an important role in vent gas ignition, the presentation will show how effective hot particle filters can be designed and integrated into venting units, with additional early-warning gas sensors for enhanced pack safety management.