The components and fire and smoke during thermal runaway of lithium-ion cells and modules have been characterized at different SOC, and for different cell formats, sizes and chemistries. In addition, large cell formats have been studied at various SOC for characterization of particulate emissions. The results of the research studies will be presented.

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? Or is there another root cause?

Lithium-ion batteries fail on rare occasions, and can cause potential risk for users and peripheral systems. In a battery recall assessment, original equipment manufacturers (OEMs) should act to minimize the risk to consumers, while providing sound technical solutions to potentially recover and replace batteries. This talk will discuss the recall process and important aspects OEMs should consider when managing a recall, including: CPSC interactions, root cause analysis, future failure predictions, risk analysis to determine whether a recall is warranted, recall scope limitation through traceability, and ensuring that replacement products resolve the issue at hand, and also minimize future risk.

To design safer lithium-ion batteries for electric vehicles, a combination of experiments, diagnostic techniques, and multiphysics modeling tools are needed to understand how various abuses, such as mechanical crush, lead to electrical and thermal failures. NREL’s Battery Abuse Diagnostics Laboratory can test and diagnose batteries under various abuse conditions, such as dynamic impact, providing data as input to safety models to provide guidance on designing safer cells and modules. We will discuss capabilities of this laboratory, our multiphysics models, and how these tools can shed light on how various incidents may lead to thermal runaway, and how to prevent them. 

This study investigates the impact of the thermal propagation reaction on the breakdown voltage inside a battery. Single thermal runaway cell tests in an autoclave yielded a gas composition, which was recreated omitting particles. The specific Paschen’s law equation for this gas was obtained. Using venting gas from a battery module, the breakdown voltage with and without particles was compared.

Understanding the failure behaviors of lithium-ion batteries can help to improve the battery safety by providing guidelines for the design in battery management system, regulations for transportation of batteries and battery-containing devices, as well as the root-cause investigation in battery-involved accidents. Accelerating Rate Calorimetry (ARC) was used to study the influence of lithium-ion battery energy and state of charge (SOC) on the thermal behavior and failure mode. Characteristic events were found to occur at much lower temperatures and faster rates with increased cell SOC. X-ray Computed Tomography (CT) was then applied to understand to reveal the fingerprints of cells failure.

"Right to Repair" initiatives were born out of consumer and independent repair shop frustration with devices that were either not feasible to repair due to their design or the required tools and spare parts were not available from the manufacturer. On balance, some manufacturers have concerns that safety might be compromised by improper repairs. This presentation will sample current federal, state, and local legislative efforts and focus on the overall pros and cons of implementation specific to the battery industry.