Effect of fatigue/ageing on the lithium distribution in cylinder-type Li-ion batteries

The lithium concentration in the graphite anode of fatigued (cycled 1000 times at 25 degrees C) Li-ion cell of 18650-type has been probed non-destructively by spatially resolved neutron diffraction. The amount x of Li in LixC6 has been determined in a central plane of a cylinder-type Li-ion cell. A radial mesh with a gauge volume of 2 x 2 x 20 mm(3) was used. Besides the evidently lower lithiation grade, caused by a lack of free movable lithium and a loss of electrolyte, a development of fatigue-driven spatial lithium in homogeneities has been observed in radial direction. Observed changes have been discussed in light of their correlations to an increase of the internal cell resistance and to a change of the electrolyte concentration. (C) 2017 Elsevier B.V. All rights reserved.