Matthew Lacey | Scania: How can you map the health of an entire battery electrode in under an hour?
13:41 - 15:30
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How can you map the health of an entire battery electrode in under an hour?
Characterizing degradation across the vast surface of a large-format cell presents a major statistical challenge. To address this, Scania is developing novel high-throughput methods. The first is a surprisingly simple yet powerful technique using a standard document scanner to capture a high-resolution, perfectly flat, and reproducible image of the entire electrode. This image can then be processed with analysis software to automatically segment and quantify the area covered by visible degradation, such as lithium plating, providing a complete surface map in less than an hour.
For a deeper electrochemical understanding, a more advanced technique called ULCER (Unlocking Localized Cell State Estimation with a Reference electrode) has been developed. This method uses a reference electrode to measure the local open-circuit potential at numerous points across the electrode surface. By combining these potential measurements with a sophisticated fitting model, it becomes possible to estimate the local loss of lithium inventory (LLI)—a key degradation mode—at each point.
The ULCER technique transforms discrete point measurements into a continuous 2D map that visualizes the distribution of degradation within the cell. These generated maps of local state-of-health show excellent correlation with the physical patterns of lithium plating identified by the scanner-based image analysis. This powerful combination of methods provides a level of detailed, spatial information about the battery's internal state that is simply impractical to achieve with traditional, small-sample analysis techniques like harvesting coin cells.
In this short video, you can learn:
* A simple yet powerful method using a document scanner to quantify visible electrode damage.
* The principles behind ULCER, a novel technique for mapping local loss of lithium inventory.
* How to create detailed 2D maps of a battery's internal state of health.
📋 **Clip Abstract** Matthew Lacey of Scania unveils two new methods for rapidly characterizing uneven battery degradation. He explains how a simple document scanner and an advanced electrochemical mapping technique called ULCER can create detailed maps of a battery's internal health.
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#DocumentScanner, #ULCER, #LithiumPlatingMapping, #LossOfLithiumInventory, #ElectrochemicalMapping, #HeavyDutyVehicles
This is a highlight of the presentation:
Towards quantifying heterogeneous degradation in lithium-ion batteries
More Highlights from the same talk.
05:25 - 08:16
Why can one part of a battery be nearly dead (59% SOH) while a spot just centimeters away is perfectly healthy (91% SOH)?
Why can one part of a battery be nearly dead (59% SOH) while a spot just centimeters away is perfectly healthy (91% SOH)?
Heterogeneous degradation is a critical challenge in large-format battery cells, where aging occurs unevenly across the electrode surface. Instead of a uniform decline in performance, localized "hotspots" of severe degradation can form, often appearing as visible surface deposits or damage. This phenomenon is particularly pronounced in cells for commercial vehicles, which have massive electrode areas measured in square meters, making some level of non-uniformity almost inevitable.
The root cause lies in the unavoidable local variations within a large cell. Small differences in current density, temperature, or mechanical pressure—stemming from cell design, module integration, or manufacturing tolerances—are magnified by demanding use cases like long-distance trucking and fast charging. These seemingly minor inconsistencies can create a feedback loop where a slightly stressed area degrades faster, which in turn increases its stress, leading to runaway local aging.
The consequences of this uneven aging are severe. The speaker presents real-world teardown data showing a cell where one location has only 59% of its original capacity, while another area just a few centimeters away retains 91%. This extreme internal imbalance is a primary driver of "knee point" behavior, or "sudden death," where a battery's performance appears stable for a long time before suddenly and unexpectedly collapsing. Understanding and mitigating this heterogeneity is key to achieving the 1.5 million kilometer lifetimes required for electric trucks.
In this short video, you can learn:
* What heterogeneous degradation is and why it's a critical issue for large-format EV cells.
* How local state-of-health can vary dramatically (from 59% to 91%) within a single cell.
* The direct link between uneven degradation and sudden, unexpected battery failure.
📋 **Clip Abstract** Matthew Lacey from Scania introduces the critical challenge of heterogeneous degradation in large EV battery cells. He reveals how uneven aging can lead to extreme local variations in health and is often the culprit behind sudden battery failure.
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#HeterogeneousDegradation, #KneePointFailure, #DegradationHotspots, #LargeFormatCells, #ElectricTrucks, #HeavyDutyEVs
11:15 - 13:02
Is your battery being killed by internal electrolyte currents or by crushing mechanical stress?
Is your battery being killed by internal electrolyte currents or by crushing mechanical stress?
Two primary hypotheses are explored to explain the root causes of heterogeneous degradation in large, constrained battery cells. The first, based on research from groups like BMW, points to a complex mechanism called "electrolyte motion induced salt in-homogeneity." As active materials swell and contract during charging and discharging, the fixed volume of the cell casing forces electrolyte to be squeezed and flow. This convection can create large, persistent gradients in the lithium salt concentration, leading to areas with depleted or concentrated electrolyte that then experience accelerated degradation and lithium plating.
A second, complementary hypothesis focuses on the direct impact of mechanical stress. Teardown analysis from Scania provides strong evidence that high local pressure is a direct trigger for lithium plating, a major degradation mechanism. This stress can arise from several sources: the tight bends in wound jelly rolls, or the cumulative swelling of many pouch or prismatic cells stacked in a module. In a module, the cells in the center can experience immense pressure as they are compressed by their expanding neighbors, creating a "hotspot" for mechanically-induced degradation.
These two advanced theories—one based on fluid dynamics and chemistry, the other on solid mechanics—are not mutually exclusive and represent the cutting edge of battery degradation research. The speaker emphasizes that other factors, such as thermal gradients or even too-low compression, also play a significant role. Identifying the dominant mechanism for a given cell design and use case is crucial for developing strategies to ensure uniform aging and long life.
In this short video, you can learn:
* An advanced degradation theory: "electrolyte motion induced salt in-homogeneity."
* How high mechanical stress from cell swelling or electrode winding can cause localized lithium plating.
* The key physical risk factors that accelerate uneven aging in large-format battery cells.
📋 **Clip Abstract** Scania's Matthew Lacey delves into the advanced physics behind why large batteries age unevenly. He contrasts two leading theories: one involving electrolyte flow and salt gradients, and another focusing on high mechanical stress causing localized damage.
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#ElectrolyteMotion, #SaltInhomogeneity, #MechanicalStress, #LithiumPlating, #LithiumIon, #EVBatteryAging