BCI Battery Poster Research Showcase

2025 Poster Submissions:

Operando Observation of Internal Structural Changes of a Lead-Acid Cell by Synchrotron X-Ray Micro Computed Tomography

Seongjun Kim, Argonne National Laboratory

Lead acid batteries (LABs) are widely used in SLI (Starting, Lighting, and Ignition) and stationary applications due to their low cost, high recyclability, and robust safety. However, their operational challenges—low specific capacity, limited cycling life, and active material degradation—continue to constrain long-term performance. In this study, we employed synchrotron X-ray microtomography and energy dispersive diffraction (EDD) to investigate the chemo-mechanical evolution of LAB cells during formation and cycling. Our custom-designed cells mimic actual LAB structures while enabling operando analyses. The observed decrease in utilization after each cycle is consistent with both electrochemical tests and EDD patterns, and this degradation is further confirmed by tomographic imaging. The positive and negative electrodes undergo distinct active materials conversion and gas evolution, resulting in different void evolution behaviors. Additionally, the positive electrode’s current collector develops a corrosion layer, whereas the negative electrode exhibits a volume increase. These findings underscore the complex interplay of active materials conversion, gas evolution, and electrode morphology in determining LAB performance, offering new insights into degradation mechanisms and informing strategies for improved LAB design.

Expander Molecules for Lead Batteries: A Framework for Structure-Function Predictions of Charge and Discharge Enhancement

Ronald Emmons, Argonne National Laboratory

Traditionally, lead acid batteries utilize lignosulphonates as additives called expanders to improve performance and limit degradation from passivation and other structural changes. While they promote better discharge performance, they do slow down charge acceptance – via a mechanism that is not entirely understood. This ambiguity is due to the complexity of the molecules and uncertainty about exact chemical identity. To better provide guidance on the design of these additives, we have developed model expander molecules (MEMs). These lignin-inspired molecules are much simpler in complexity, allowing them to be characterized in more detail (e.g., molecular weight, functionality). In addition to these more holistic properties, electronic properties were calculated utilizing density functional theory (DFT), providing a greater understanding of what properties govern enhancements in discharge and charge. In this work, MEMs were evaluated using a rotating disk electrode setup with flat lead in sulfuric acid in the presence of MEMs, giving us the ability to determine the MEMs enhancement. Combining electrochemical data with the calculated chemical properties, we begin establishing a framework to 1) understand what properties impact charge and discharge characteristics for more thorough design rules and 2) predict novel compounds with targeted molecular features towards finding better additives. This is accomplished using predictive machine learning algorithms to calculate charge and discharge characteristics. In its current state, a variety of MEMs have been discovered that can enhance both charge and discharge capacity, and their properties are being scrutinized for further chemical discovery and the design of advanced expanders for lead acid batteries.

Acoustic Characterization of Lead Acid Batteries

Tim Fister, Argonne National Laboratory

Local variation in electrode and electrolyte composition contributes to large-scale changes in overall utilization and cycle life of lead acid batteries. Here, we outline the potential for ultrasonic characterization of lead acid batteries to diagnose local changes in state of charge (SOC) and state of health (SOH). Using 2V cells constructed with commercial battery plates, we show that the amplitude and time-of-flight of ultrasonic signals is highly sensitive to changes in the bulk modulus and density of lead battery materials and acid specific gravity during cycling. Using high-rate partial state of charge cycling, we also show that these changes can be used to track the onset of sulfation on the negative electrode. This nondestructive, analytical tool can provide crucial feedback for emerging battery management systems and could potentially be used for quality control measures during manufacturing.

Design and Development of a Custom Battery Pack and Monitoring System for an ASC Single-Occupant Solar Vehicle by Longhorn Racing Solar, UT Austin

Parthiv Shah, Longhom Racing Solar – The University of Texas at Austin

The battery pack for Longhorn Racing Solar’s single-occupant solar vehicle is engineered to compete in two demanding events: the Formula Sun Grand Prix (FSGP) and the American Solar Challenge (ASC). FSGP’s race-style format stresses the battery with rapid accelerations and decelerations, while ASC’s 1500-2000 mile endurance race on real roads requires robust design and sustained performance over extended runtimes. Efficiency, safety, and energy density were prioritized under strict size and weight constraints. Efficiency was achieved by minimizing internal resistance losses and optimizing weight to enhance performance and reduce energy consumption. Positioned directly behind the driver, the battery incorporates a custom-designed Battery Protection System (BPS), which replaces off-the-shelf solutions used by most teams. This system allows exceptional customizability and seamless integration with the pack, enabling advanced monitoring of individual module temperatures and voltages. The BPS isolates the battery during anomalies, triggers a fault state, and alerts the driver, ensuring optimal safety and reliability. The pack features a 32S 9P configuration, delivering a nominal voltage of 118V, a maximum current output of 70A, and a capacity of 5.22 kWh in a compact form factor. The enclosure, made of carbon fiber, Kevlar, and Gurit Kerdyn foam core, provides insulation, fire resistance, and structural integrity while maintaining a lightweight design. Forced-air cooling ensures thermal stability, with liquid cooling solutions under consideration for further optimization. Modular and serviceable, the pack uses linear latches with a cable release system for secure mounting and quick removal. This innovative system meets the rigorous demands of solar vehicle competitions.

Accelerating Lead-Acid Battery Innovation: Automated Screening and Analysis of Model Expander Molecules

Igor Messias, Argonne National Laboratory

Organic additives are essential for optimizing the performance and longevity of lead-acid batteries, as they enhance electrochemical properties and overall efficiency. By increasing the surface area of active materials, additives facilitate electrochemical reactions, thereby boosting the battery’s discharge capacity. Understanding the structure-activity relationships of these additives is crucial for tailoring their properties to enhance battery performance. Systematic studies using cyclic voltammetry evaluated the electrochemical characteristics of over a hundred model expander molecules (MEMs), providing insights into their ability to improve or decrease the discharge and charge processes of the negative active material. Based on this workflow, an autonomous system can exponentially accelerate the screening of MEMs by automating data collection and analysis, significantly increasing throughput and precision. To accelerate the screening process, we have implemented the Electrochemical System for Molecule Autonomous and Rapid Testing (ESMART). This system is designed to allow for mixing up to six simultaneous solutions containing different MEMs or electrolyte compositions. Our platform is controlled using a Python-based interface, allowing for the automation of electrochemical experiments and data analysis. This approach enables the rapid processing of extensive datasets and serves as a key pillar in predicting performance metrics such as discharge enhancement factors (DEF) and charge enhancement factors (CEF). This advancement supports the establishment of design principles for expander molecules tailored for advanced lead-acid battery applications. Furthermore, the ability to quickly and accurately assess a wide range of MEMs not only enhances the understanding of additive behavior but also accelerates the innovation cycle, paving the way for next-generation energy storage solutions for any application.

Model Expander Molecules: From Synthesis to Applications in Lead Acid Batteries

Sahar Nazeer, University of Toledo

With the development in science and technology and increased demands of energy, lead acid batteries have attracted the attention of researchers because of their safety, simple manufacturing, low cost, and 99+% recyclability. However, certain issues like sulfation limit the life cycle of the batteries. Sulfation is the irreversible formation of lead sulfate crystals on the battery’s negative electrode, which is related to the size and shape of the crystals. Various strategies have been employed to overcome this issue. Expanders are added to the negative electrode, which affect the morphology of lead sulfate crystals and prevent the loss of performance of the negative electrode. These include lignosulfonate, carbon black, and barium sulfate. Lignosulfonates are complex molecules with many different functional groups, which improve the discharging capacity but impede charging. It is still unclear which functional groups of lignosulfonates are responsible for improved performance and which have detrimental effects. It would be ideal to develop expander molecules that will improve both charge and discharge capacity. To design such molecules, it is important to understand the atomic level interactions between lead species and lignosulfonates. Small molecules with functional groups that mimic the functional groups of lignosulfonates were synthesized and named Model Expander Molecules. These molecules were synthesized by sulfonation and alkylation of simple organic starting materials and characterized by NMR spectroscopy and ESI mass spectroscopy. When applicable, the absence of inorganic byproducts was confirmed by powder diffraction and energy dispersive X-ray spectroscopy. Electrochemical studies were conducted in 5 M sulfuric acid solution and stability was tested by cyclic voltammetry. For further electrochemical studies, these molecules were sent to Argonne National Lab before testing in a real device.

The Effect of Size and Morphology of PBSO4 Particles on the Charge Acceptance of Lead Acid Batteries

Kaline Nascimento da Silva, Argonne National Laboratory

Lead Acid Battery (LAB) is a reliable energy storage solution for vehicles and future electrical grids, presenting low cost, high power, and highest recyclability rates than any other battery technology. However, low material utilization, limited cycle life, and, most importantly, slow rechargeability are key technical limitations that need to be addressed for advanced lead battery systems. At the molecular levels, the process of converting PbSO4 back into Pb at the negative electrode or PbO2 at the positive electrode involves a combination of chemical and electrochemical steps, which need to be better understood to afford control over the recharging rates and prevent cycle life issues such as sulfation. To gain insights into the charging process of PbSO4, in this work we use a double injection precipitation method to synthesize lead sulfate particles with controlled size and shape. By tuning the synthesis conditions, we were able to synthesize particles with different size ranges: 150-170 nm, 250-270 nm, 300-340 nm, and 1.2 µm, in two different shapes, rhombohedral and cubic. These chemically synthesized lead sulfates were used as platform to understand the effect of size and shape in the charging step on both negative and positive electrodes. For both particle shapes, smaller particles charge faster than bigger particles. However, for similar sizes, rhombohedral particles are far more efficient in charging than cubic-shaped particles, and thus, rhombohedral PbSO4 presents the highest kinetic charge acceptance. This study offers new insights on how to control the charging process of lead batteries, with possible consequences to its manufacturing and improving the formation step, reducing the energy use in manufacturing and towards the development of advanced lead acid batteries.

Morphological and Allometric Analysis of Precipitated Lead Sulfate in The Presence of Model Expander Molecules

Daniel Landeros, University of Toledo

Principal to motor vehicles, power retention systems, and many other applications, rechargeable lead acid batteries facilitate the need for power storage due to their innate reliability and safety. The primary reaction that occurs within these batteries creates insoluble lead sulfate at both electrodes. This accumulation causes gradual impedance to battery performance and eventual inoperability. A common method used by manufacturers to combat this effect is to include additives known as expanders, which improve performance and cycle life by influencing lead sulfate formation. Lignosulfonates are one expander that can be used to significantly increase battery charging performance at the cost of discharge interference. The lignosulfonate expanders affect morphology of the lead sulfate and the porosity retention of the negative electrode, but the atomic level interactions and mechanisms are not known. Our group has proposed to gain insights into why this happens by synthesizing model expander molecules (MEMs) that mimic specific functional groups of lignosulfonates. The MEMs’ effects on charge and discharge are then analyzed utilizing experimental conditions akin to the environment of a lead acid battery. For this project, lead sulfate is precipitated out by controlled additions of lead nitrate to an aqueous solution of sodium sulfate and a chosen MEM. The lead sulfate samples are dried and then analyzed with powder x-ray diffraction and scanning electron microscopy (SEM). The impact of MEM and addition rate is qualified by visual inspection of particle morphologies in SEM images. Furthermore, to gain quantitative insight, a novel technique utilizing Meta’s Segment Anything Model is applied to SEM images to identify and isolate particles to subsequently determine approximate exposed surface areas and distributions. These results are then correlated to the MEMs effects on discharge capacity and kinetic charge acceptance.

Accelerating Redox Flow Battery Development Through an Autonomous Flow Battery Cycler Station

Cailin Buchanan, Argonne National Laboratory

Redox flow batteries (RFBs) are a promising technology for long duration energy storage (LDES) because of their theoretically long cycle life and scalability. Although the state-of-the-art RFB is vanadium-based, it is not economical due to vanadium’s price volatility and low voltage. Thus, RFBs with alternative electrolytes must be explored. Organic RFBs are attractive due to their low-cost, earth-abundant materials, however, many systems suffer from poor stability and low energy density. Given the vast parameter space for RFB electrolytes, including active materials and supporting electrolytes, the pace of research urgently needs to be quickened to identify systems that are stable and have high energy densities. To accelerate the development of RFBs, we have built an automated flow battery cycler station that can explore a large parameter space and leverage artificial intelligence (AI). The automated platform contains sixteen electrochemical testing channels, each comprised of four peristaltic pumping channels and four selector valves that deliver electrolyte to the flow cell. One software controls both the electrolyte delivery system and the electrochemical testing, resulting in complete automation and closed-loop capabilities. To test the automated station, we collected electrochemistry results for commonly proposed redox active materials like hydroxy-TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) and supporting salts like lithium bis(trifluoromethanesulfonyl) imide (LiTFSI). The automated system was used to explore a wide range of supporting salt concentrations without human intervention, underscoring the utility of the cycler station and its potential for use in an autonomous discovery platform to accelerate LDES technology development even further when coupled with machine learning optimization algorithms.

Design, Synthesis and Structural Evaluation of Model Expander Molecules for Advanced Lead-Acid Battery Storage Applications

Madhu Chennapuram, University of Toledo

Lead acid batteries provide a day-to-day reliable energy storage application in various fields like automotive, standby power, renewable energy, telecommunication, industrial and robotics.1 In addition to the electrochemically active lead species, these batteries contain several additives that improve performance and cycle life. Lignosulfonates (LS) are organic biopolymers that are used as additives in a variety of applications, including the production of lead acid batteries2 (Figure 1). In lead acid batteries, LS serve as organic expanders to improve the performance of the battery’s storage capacity and extending its service life, as well as by acting as a wetting agent and improving the conductivity of the electrolyte, which tends to improve battery efficiency.3 To be able to understand the interaction of specific functional groups with lead species in detail, small molecules that mimic portions of LS can be used as model expander molecules (MEMs). In this study, we designed and synthesized lignosulfonate-based MEMs (Figure 2). The MEMs stability under conditions relevant for battery applications was investigated by cyclic voltammetry in 5 M H2SO4. Additionally, the interaction of the MEMs with Pb2+ and their stability at elevated temperature and in 5 M sulfuric acid was studied by spectroscopic, diffraction and single-crystal X-ray diffraction techniques.

Electrochemical Impedance Spectroscopy on Lead Acid Battery Positive Active Material during Cycling.

Frederick Agyapong-Fordjour, Argonne National Laboratory

Batteries are poised to play a key role in a sustainable energy future as they are essential for scalable energy storage solutions, particularly for intermittent renewable sources such as solar and wind. Battery condition indicators, such as the state of charge (SOC) and state of health (SOH), are critical for effective battery monitoring and control. However, these indicators are not easily accessible from simple voltage/current measurements and must instead be estimated using models. This is challenging because they are influenced by operating conditions such as temperature and charge/discharge rates, resting periods, etc. Electrochemical impedance spectroscopy (EIS) is a very useful tool that could be used to track batteries’ SOH because of its accurate determination of equivalent resistances that help us characterize electrochemical processes via the ohmic (solution) resistance (Rs), charge transfer resistance (Rct), and double layer capacitance (Cdl) that in turn can help us estimate electrochemical active surface area (ECSA). In this work, we used EIS to track Cdl, Rct, and Rs of the positive active materials (PAM) of lead acid batteries to probe battery failure mechanisms such as materials loss and grid corrosion that are influenced by the charge cut-off potential and the presence of gassing reactions. We observed a correlation between Rct and Rs because gassing causes material loss due to adhesion and cohesion changes within the active material (expansion) and grid corrosion. A direct correlation was also observed as discharge voltage drop seems linked to a decrease in Cdl, ECSA and electrode capacity. Thus, EIS obtained metrics such as Cdl, Rct and Rs could serve as state of health indicators for positive active materials of lead acid batteries.

Deciphering Failure Mechanisms and Material Evolution in Pb NAM Pasted Electrodes: Relationships between Surface Area, Morphology, and Electrochemical Dynamics

Alejandra Medrano Banda, Argonne National Laboratory

Despite lead-acid batteries widespread use as an energy storage solution due to their abundant and low-cost materials, improving their durability requires a deeper understanding of negative active material (NAM) processes affecting cycle life. Our group previously demonstrated how discharge rates influence PbSO₄ particle size/layer thickness, governing NAM capacity and battery performance. While those studies were performed on well-defined lead surfaces, establishing the connection to the performance in high surface area pasted electrodes is paramount to connect the fundamental processes for the design of high material utilization and long-lasting electrodes. This work focuses on using pasted NAM electrodes to investigate the impact of discharge rates, depth of discharge (DOD), and overcharge on performance, its degradation and material evolution. Through electrochemical impedance spectroscopy the electrochemical surface area (ECSA), high-frequency resistance, and charge transfer resistance, were determined to establish a connection to Peukert’s law. Discharge capacities normalized by ECSA aligned the expected Peukert curve from flat Pb surface. However, the 3D porous structure, higher discharge rates and deeper DODs lead to inconsistent capacity retention and reduced cycle life. Even at lower DODs, prolonged overvoltage conditions at gas evolution potential induced loss in capacity retention, likely due to active material disturbance by gas bubbles. Comparisons of throughput capacities indicate that slower cycling rates and lower DOD conditions yield higher material utilization and extended cycle life. These findings provide valuable insights into how specific failure mechanisms contribute to performance degradation, establishing groundwork to create mitigation strategies and enhance the longevity and efficiency of lead-acid batteries.

Thermal and Chemical Stability Analysis of Battery Active Materials

Ayrton Yanyachi, University of Texas at Austin

The thermal and chemical degradation of battery active materials is a critical area of study for improving safety and thermal stability in energy storage systems. The research explores the mechanisms behind thermal runaway, quantifies heat generation, investigates reaction kinetics, and analyzes degradation pathways through a combination of experimental and modeling approaches. Advanced calorimetry techniques, including Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Accelerating Rate Calorimetry (ARC), are employed to examine material behavior under varying thermal conditions. To achieve a comprehensive characterization, evolved gas analysis (EGA) and X-ray diffraction (XRD) are used in parallel to identify gas evolution pathways and structural transformations during degradation. These techniques provide critical insights into the physicochemical changes occurring in battery materials at elevated temperatures Moreover, the modelling framework focuses on estimating heat generation, deriving kinetic parameters, and simulating thermal runaway scenarios at the cell level. This integrative approach bridges experimental observations with theoretical models, enabling a deeper understanding of thermal events in batteries. By combining state-of-the-art experimental techniques with robust modeling, this research contributes to the broader goal of mitigating safety risks in modern battery technologies.