Batteries lose lithium to the current collector
Observations using atom probe tomography support the suspicion that lithium ions are lost to the copper current collector in lithium batteries. This could limit their performance and lifespan.
Any loss of lithium leads to a loss of capacity in lithium batteries and shortens their lifespan. Following recent research suggesting that lithium is lost to the current collector during charging, researchers from Ruhr University Bochum, led by Prof. Dr. Tong Li, the Helmholtz Institute Ulm, and the Karlsruhe Institute of Technology, led by Prof. Dr. Dominic Bresser, have rigorously tested this hypothesis. Using atom probe tomography, they were able to demonstrate that lithium ions are indeed bound to the copper current collector. This loss increases with the number of charging cycles, even in state-of-the-art battery types. “Understanding these processes is of great importance for anode-free batteries of the future,” says Tong Li. The researchers report their findings in the journal Advanced Energy Materials on July 10, 2026 .
Precise 3D maps of any element
The copper current collector is a thin copper foil that serves as a support layer for the battery’s anode and collects electrons to conduct them to the negative terminal. In lithium-metal batteries, lithium can diffuse into the copper current collector during the charge and discharge cycle.
Tong Li, explains:
However, it was previously unclear exactly where the lithium ions are deposited,
“Lithium in copper is difficult to detect because there is a lack of analytical methods to trace highly reactive and light lithium.”
The research team used atom probe tomography, which allows for the creation of precise three-dimensional maps of any element with sub-nanometer resolution. The results showed that even after a single charge/discharge cycle, lithium is initially bound at grain boundaries and interfaces of the copper foil. After three cycles, the surface of the copper foil becomes nanocrystalline and oxidized. The resulting defects further bind lithium and oxygen below the surface, leading to the degradation of the copper current collector.
Lithium loss in new battery technology previously overlooked
Tong Li, explains:
All this information is crucial for understanding how the current collector influences the performance of future lithium batteries,
Lithium-metal hydride batteries (LMBs), and more recently so-called “zero-excess” or “anode-free” LMBs, are considered the next significant steps toward even higher energy densities. They far surpass the currently dominant lithium-ion technology.
Tong Li, says:
With zero-excess LMBs, it is generally assumed that lithium does not diffuse into or interact with the copper current collector,
“In discussions about the performance degradation of LMBs, the loss of lithium to the copper collector has been largely overlooked.”
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Batteries lose lithium to the current collector, source
