This presentation introduces a novel Electrochemical Impedance Spectroscopy (EIS) method for detecting the growth of lithium metal plating within lithium-ion batteries. This method can be assembled either as a sensor or as an instrumental system to diagnose the safety degradation associated with battery reusing.

This work presents a case study evaluating the reliability of a model-based battery state estimation framework, where we tested the algorithm on pack-level data from beginning, middle, and end of battery life.

This presentation details a project funded by the Department of Transportation to better understand the metrics and response times of commercial and novel sensor technologies. The capability of these sensors to identify markers of imminent failure in cells and battery packs is a critical component of the project, and the main topic of discussion during this presentation.

Rechargeable lithium-metal batteries (LMBs) are viewed as the next important leap forward in lithium battery technology. Providing higher energy density than state-of-the-art lithium-ion batteries, LMBs have been largely held back by safety concerns and insufficient cycle life. Recent advances have made lithium metal viable for commercial production, though mathematical models of this chemistry have been slow to appear. This work introduces a closed-form impedance model for lithium metal chemistry and points the way toward reduced complexity model forms amenable to battery management system (BMS) applications.

Lithium-metal batteries (LMB) have recently emerged as a contender due to their inherently high specific energy (300 -550 Wh kg-1 versus 100-265 Wh kg-1  for lithium-ion), making them particularly appealing in heavy-duty class 4-8 trucks and buses. Advances in design have overcome many of the detractors (poor cycle-life and safety concerns) and LMB now show promise for commercial development.  Like lithium-ion batteries (LIB), LMB require careful management to ensure good performance and safe operation. In this presentation, we will formulate a reduced-complexity single particle model (SPM) of LMB amenable to real-time battery management and advanced control.

In the past few years, the Electrochemical Safety Research Institute (ESRI) team has been working on characterizing the efficacy of fire suppressants on various sizes and chemistries of lithium-ion modules. The fire suppressants that have been used repeatedly for the studies are nitrogen gas, water and a commercial aerosol-based fire suppressant. The time, duration and direction of release of the suppressants, as well as reignition after suppressant use, have been studied. 

With new designs and chemistries, the performance of Li-ion batteries increases year after year. The risks associated with thermal runaway of cells change too and a challenge persists in determining whether increased performance comes at the expense of reduced safety. This work focuses on understanding correlations between heat generation and mass ejection during thermal runaway, the causes of outlier behaviors, and the predictability of risks using zero- or one-shot learning.

Multi-functional venting units are essential components in holistic battery safety concepts, enabling pressure equalization between pack interior and environment in regular operation, as well as effective overpressure release during thermal runaway, even reducing the risk of battery fires. With an increasing variety in battery pack designs and cell chemistries, the functionality of venting units must be adapted accordingly. This presentation will show current trends and solutions in venting unit engineering.

Lithium iron phosphate (LFP)-based lithium-ion batteries enable moderate range electric vehicles with safe batteries that approach mass-market acceptable price points. However, the challenge of reaching "refill" times comparable to user expectations (e.g., <10 min.) persists. This talk presents EC Power’s thermally modulated cell structure, which permits extreme fast charging of ~170 Wh/kg LFP-based lithium-ion cells with long cycle life at both room temperature and -50 degrees Celsius.

Fast-charging can readily lead to early cell failure and reduced performance. The ability to use cell parameters for the development of advanced charge protocols provides an opportunity to tailor both the time and energy accepted to specific needs while minimizing degradation. During this talk, advanced protocols and analysis, including the use of machine learning to identify failure modes and predict performance, will be discussed.

NASA has 3 design approaches for achieving passively propagation-resistant battery designs with 18650 cells. The interstitial heat sink approach is most volumetrically efficient and achieves 459 Wh/L using 18650 cells 725 Wh/L. Scaling-up this design to 21700 designs that are >725 Wh/L presents challenges to demonstrate similar adjacent cell protection from conducted heat through the heat sink and from ejected heat diverted by blast plate barriers and channels.

Controlling the microstructure of porous Li-ion electrodes can considerably improve their energy- and power-density. However, scale-up of cost-effective structuring techniques to high-throughput roll-to-roll production is challenging. In this work, we focus on the use of laser-ablation for high-throughput roll-to-roll production of structured electrodes, with enhanced fast-charging and long-life capability. This talk will cover the challenges, performance benefits, and economics associated with scaling to roll-to-roll production of laser-ablated structured electrodes.

We compare the cell formats PHEV1, pouch, 21700, and 18650 with the same cell chemistry on pilot-scale. Conclusions are drawn on the effect of cell design on rate capability, cell resistance, heating behavior, and cycling aging. The results are put into context with commercial cells.

The Department of Defense fields a wide variety of batteries with unique requirements and operating environments. While many of these can be met with commercially available battery technology, existing and emerging requirements call for new developments in science and technology (S&T). This talk will give an overview of the DoD Battery S&T Strategy and high-level needs across all domains.

Battery systems are complex systems with the battery cell as the core technology of the system but then integrated with multiple subsystems, including mechanical, thermal, and battery management systems (BMS). This presentation will look into the different subsystems that contribute to the overall battery system performance and opportunities for improvement in next-generation battery systems. Battery system trends in the industry will be evaluated and discussed.