Lithium distribution and transfer in high-power 18650-type Li-ion cells at multiple length scales

The distribution of lithium inside electrodes of a commercial Li-ion battery of 18650-type with LiFePO₄ cathode and graphite anode is investigated on different length scales using neutron diffraction, X-ray (synchrotron-based) diffraction and X-ray computed tomography. Evolution of 2D (in-plane) lithium distribution in lithiated graphite is monitored during charge/discharge using millimeter-sized spatial resolution. Micrometer-sized details of cell organization and lithiation of both the positive and negative electrodes are obtained from diffraction-based tomography applying synchrotron radiation. In-situ lithiation of the cathode over its thickness and development of the lithium concentration front during cell charge/discharge is traced by diffraction-based profiling with a micrometer-sized synchrotron beam in a single-layer electrochemical cell.