In-situ measurements of mechanical and volume change of LiCoO2 lithium-ion batteries during repeated charge-discharge cycling by using digital image correlation

In-situ morphological evolution of displacement in pouch-type commercial lithium-ion batteries during multiple fifty-five electrochemical charging-discharging cycles was measured via digital image correlation technique. The maximum principal strain on the battery surface reached 0.35% during 55 cycles. The whole volume change analysis of LIBs shows that the maximum volume change rate arrives at 4.27% at the fully 52nd charging end, and the maximum residual volume change rate is about 2.89% at the 54th discharging end. The surface morphologies of cathodes and anodes before and after electrochemical cycling were observed by scanning electron microscopy. The elastic modulus of the copper foil in LIBs decrease from as-received 16.7 GPa to 10.6 GPa after 55 cycles by using tensile tests.