LG 21700 M50 Cell

Thermal Abuse Testing

Cycling

Nikon XT 225 scan of two LG 21700 M50 cells after thermal abuse testing (left).

In the cell on the left (green) the "jellyroll" (the cyclinder of wrapped up electrodes in the centre of the cell) has been ejected out of the casing by the rapid evolution and expansion of gas, leading to large voids.  In the cell on the right (red) the jellyroll has remained within the cell.

Nikon XT 225 scan of an as-received ('pristine') LG 21700n M50 cell (left).
These cells are designed for high energy primarily for the automotive industry.

Nikon XT 225 scan of an LG 21700 M50 Cell after cycling (left).

The cell appears largely similar to the as-received sample.  However, the jellyroll has begun to buckle at the centre of the cell, leading to lower stability and safety.