Researchers have uncovered a major factor behind how batteries decline, revealing why the power cells used in everything from smartphones to electric vehicles gradually lose performance over time.
A collaboration between teams at The University of Texas at Austin, Northeastern University, Stanford University and Argonne National Laboratory has shown that each charge–discharge cycle makes a battery subtly expand and contract, much like breathing. Over time, this repeated motion causes tiny distortions within the cell, placing strain on internal components and reducing overall performance – a key reason batteries decline.
This process, described as chemomechanical degradation, helps explain why batteries decline and has long challenged engineers seeking to extend battery life.
“With every ‘breath’ of the battery, there’s some degree of irreversibility,” said Yijin Liu, leader of the study, “This effect accumulates over time, eventually causing failure of the cell.”
A key breakthrough in the study was the identification of “strain cascades” – stress that begins in one part of an electrode and then spreads to neighbouring areas. Because batteries contain vast numbers of particles that behave unpredictably, this uneven movement can create localised stress points.
According to co-author Juner Zhu, “Some particles move rapidly, like shooting stars in the sky, while others remain relatively stable. This uneven behaviour creates localised stress that can lead to cracks and other damage.”
By mapping how this strain forms and travels, the researchers believe engineers can design electrodes better able to withstand mechanical stress. The study also suggests that applying controlled pressure to cells may help limit damage and improve durability.
Using advanced imaging tools such as operando TXM and 3D X-ray laminography, the team captured real‑time particle movement during cycling. Their next steps involve developing theoretical models to deepen understanding of these chemical–mechanical interactions.
