State-of-Charge Mapping in Batteries

State-of-charge mapping (left) and morphology (right) via STXM and TEM, respectively, of regions in the LFP composite electrode (A) 26 μm, (B) 18 μm, and (C) 6 μm from the Al current collector. Colors indicate the local state of charge, and brightness gives the LFP thickness. Outlined in white are particles in which two phases coexist.

Scientific AchievementWe can now visualize the motion of lithium ions for a

significant number of battery particles at the nanoscale.

Significance and ImpactBy tracking the movements of lithium ions, scientists can

decipher the process that ultimately limits the rate of battery charge and discharge in lithium-ion batteries.

Research Details−Combination of synchrotron-based scanning transmission x-ray

microscopy (STXM) and transmission electron microscopy (TEM).−Previous work focused on either the behavior of a single particle or

the spatially averaged behavior of the entire battery electrode.−Technique enables visualization of lithium-ion distribution down to

10 nm for hundreds of battery particles at a time.−Results confirm that charge rate is limited by the initiation rate of

phase transformation.W.C. Chueh et al., Nano Lett. 13, 866 (2013).

Work was performed at Lawrence Berkeley National Laboratory, ALS Beamlines 5.3.2 and 11.0.2. The operation of the ALS is supported by the U.S. Department of Energy, Office of Basic Energy Sciences.

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