Engineered temperature gradients may help lithium-ion batteries charge faster with less damage

Researchers have identified how in-plane temperature gradients inside lithium-ion batteries can either protect cells during fast charging or dramatically accelerate their degradation, offering a new way to think about battery thermal management. The study suggests that not all temperature gradients are harmful by default. Instead, performance depends on whether the hotter regions inside the battery are spatially aligned with the areas carrying higher current density.

Temperature is already known to strongly influence battery behavior, affecting reaction kinetics, internal resistance, polarization, charging speed, and safety. But in practical battery packs, temperatures are rarely uniform. High currents, tab geometry, and uneven heat dissipation can create temperature differences across the plane of a cell, especially under fast-charging conditions. Until now, however, the role of such in-plane temperature gradients in driving degradation has remained insufficiently understood, making it harder to design thermal strategies that improve charging performance without triggering lithium plating or structural damage.

In the new study, the researchers artificially constructed an in-plane temperature gradient between the battery tabs and the bottom region of a cell and then carried out fast-charging cycling tests. To understand what was happening inside the battery, they combined experiments with post-mortem analysis of the anode surface morphology and elemental distribution after cycling. They also developed a three-dimensional electrochemical model to simulate internal parameter distributions during fast charging. This combined approach allowed them to connect externally imposed temperature conditions with the internal electrochemical nonuniformities that ultimately shape degradation.

The analysis showed that battery degradation under these conditions can be divided into three stages: an in-plane current density gradient stage, an in-plane temperature gradient stage, and an emergence of degradation factors stage. In other words, degradation did not appear as a single uniform process, but as a sequence in which electrical nonuniformity, thermal nonuniformity, and damage-related phenomena progressively interacted. One of the paper's central conclusions is that inhomogeneous temperature leads to inhomogeneous lithium plating. That finding is important because lithium plating is one of the most concerning failure pathways in fast charging, as it can reduce capacity, increase aging, and contribute to safety risks.

The researchers then proposed a spatial matching criterion between in-plane temperature gradient and in-plane current density gradient. According to this criterion, battery degradation can be suppressed when the high current density region coincides with the high temperature region. In practical terms, this means that a thermal field can be beneficial if it is arranged so that the parts of the battery working hardest are also the parts kept warmer. Under that favorable configuration, where the high-current-density tabs were at higher temperature and the lower-current-density bottom region was cooler, the battery maintained more than 90% capacity after 50 cycles at a 2C charging rate.

The opposite temperature arrangement, however, had sharply different consequences. When the high-current-density region was colder and the lower-current-density region was warmer, the cell experienced lithium plating and material cracking. Under those conditions, the battery lost 34.3% of its capacity after only 5 cycles. That contrast highlights how strongly thermal nonuniformity can influence degradation pathways during fast charging. Rather than being a secondary side effect, the temperature gradient became a central factor controlling where electrochemical stress accumulated and whether damaging side reactions emerged.

The study also found that the same matching principle can improve low-temperature discharge behavior. In tests at -20 C, the discharge capacity increased by 8% when the spatial matching criterion was achieved. This suggests that the idea may have broader value than fast charging alone. If thermal regulation can be intentionally arranged to align heat distribution with current distribution, it may help reduce battery polarization and support better performance across a wider range of operating conditions, including cold environments that are typically challenging for lithium-ion systems.

Taken together, the results point to a more refined view of battery thermal management. The goal may not always be to eliminate every temperature difference inside a cell, but to control the direction and location of that gradient so it works with, rather than against, the battery's internal current distribution. Because the work combines controlled experiments, post-mortem characterization, and 3D electrochemical simulation, it offers both mechanistic insight and a design-oriented principle. Further validation will still be needed in other cell formats, chemistries, and pack-level systems, but the study suggests that appropriately engineered in-plane temperature gradients could become a practical tool for extending battery life and improving fast-charging performance.

Reference

Author:

Zhichao Li ^a, Zhiguo Qu ^a, Zhiyuan Jiang ^b, Hongbo Huang ^a, Wenquan Tao ^a

Title of original paper:

Degradation mechanism of lithium-ion battery under appropriate in-plane temperature gradient

Article link:

https://www.sciencedirect.com/science/article/pii/S2773153725001021

Journal:

Green Energy and Intelligent Transportation

DOI:

10.1016/j.geits.2025.100352

Affiliations:

a MOE Key Laboratory of Thermo-Fluid Science and Engineering, School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China

b School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China