Degradation of lithium ion (Li-ion) cells affects both performance and safety of Li-ion batteries. In order to avoid potential safety hazards, it is crucial to detect the onset and extent of critical degradation modes in commercial Li-ion cells. This work demonstrates the application of a diagnostic algorithm to identify and quantify degradation modes of commercial Li-ion pouch cells cycled at -10 degrees C and a C-rate of 2 C. Rapid loss of active negative electrode material was successfully identified and results were validated using 3-electrode cells, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The positive electrode material was less strongly affected by the tests, as found by the diagnostic algorithm and confirmed with EDX and SEM results. (C) The Author(s) 2017. Published by ECS. All rights reserved.