Battery Testing

Buston, Jonathan EH, et al. Energy Advances 2.1 (2023): 170-179.

This study investigates the solid materials and metal content released during the failure of commercially available lithium-ion batteries (LIBs) exposed to an external heat source. While much research has focused on the gaseous emissions during battery failure, this work emphasizes the analysis of solid residues and metals present in the smoke and surrounding material. Using ICP-AES, metal content was determined in the smoke filters and residue swabs from the chamber and cells after ignition and cooling.

The analysis revealed that all samples contained metals commonly found in the cathode materials of lithium-ion batteries, such as nickel, manganese, cobalt, and aluminium. The ratios of these metals varied depending on the specific cathode composition of the cell. Additionally, other metals, including copper, lithium, and iron, were detected, consistent with the anode and casing materials typically found in lithium-ion batteries.

The findings highlight the potential environmental hazards associated with the failure of lithium-ion batteries, specifically the release of hazardous metals during thermal events. The variation in metal ratios between different cell types underscores the importance of understanding the materials used in battery construction and their potential impacts in the event of failure. This study provides valuable insights into the risks posed by failed lithium-ion batteries, emphasizing the need for careful handling and disposal practices.

Liu, Jia, et al. International Journal of Heat and Mass Transfer 230 (2024): 125741.

This study investigates the anisotropic thermal conductivity and thermal contact resistance (TCR) of individual thin-layer materials in lithium-ion batteries (Li-ion batteries) to enhance the understanding of thermal behavior crucial for battery design and safety. Using a customized steady-state instrument and a commercial thermal constant analyzer, the through-plane and in-plane thermal conductivities were measured, along with inter-layer TCR.

The results reveal significant anisotropy in the thermal conductivity of thin-layer electrode materials, with through-plane conductivity notably lower than in-plane conductivity. The inter-layer TCR was found to contribute approximately 25% of the total thermal resistance of the battery. Furthermore, the study explored the temperature and pressure dependence of these properties. It was observed that the through-plane thermal conductivity slightly decreased with increasing temperature and marginally increased with pressure. In contrast, the TCR drastically decreased with both temperature and pressure increases.

The findings emphasize the importance of considering the anisotropic thermal conductivity and TCR in the thermal management and design of Li-ion batteries. These properties, along with microstructural factors such as pore distribution and particle sizes, significantly affect the overall thermal resistance and performance. This study provides valuable insights for the optimization of Li-ion batteries in terms of efficiency, safety, and longevity, guiding future thermal design, modeling, and analysis strategies.

Das, K. Rohini, and M. Jinish Antony. Journal of Energy Storage 86 (2024): 111193.

This study develops a novel ex-situ colorimetric method for determining the state of charge (SoC) in lead-acid batteries, utilizing poly-N-phenyl-o-phenylenediamine (PPOPD) as a sensing material. The PPOPD polymer, synthesized via in-situ oxidative polymerization of N-phenyl-o-phenylenediamine (POPD), shows a clear UV-visible absorption peak at 518 nm in acidic solutions, which correlates linearly with the acid content. As the lead-acid battery charges and discharges, changes in acid content occur, directly influencing the absorbance of the PPOPD solution.

The study shows that the acid content in a fully charged battery is approximately 39.7% sulfuric acid, which decreases by about 10% during discharge. The absorbance values of the PPOPD solution at 518 nm are linearly related to sulfuric acid concentrations (6–40%), representing the acid content inside the battery. The state of charge is determined by comparing the absorbance to pre-established limits (Amin and Amax) corresponding to the lower and upper sulfuric acid concentrations.

The colorimetric method's results were validated against an open-circuit voltage method, showing good correlation. This method offers an effective and accurate approach for monitoring the state of charge in lead-acid batteries, providing an alternative to traditional voltage-based methods with the potential for improved battery management and performance monitoring.