Heterogeneity in battery performance is a critical concern for manufacturers looking to maximize capacity, safety, and cell lifetime. Single layer pouch cells containing graphite anodes and LiNi0.5Mn0.3Co0.2O2 cathodes were cycled under various conditions testing the influence of cycling rate, voltage limit, uneven stack pressure, and gas generation on the uniformity of cell performance. Spot tracking of a freshly formed cell was performed under fast charge (6C) and high voltage limit (4.4 V) conditions indicating widely varying performances across the positions with no discernible influence of uneven stack pressure. Follow up mapping study comparing fast (6C) and slow (C/2) charging rates with the same 3-4.4 V window indicates that fast charge induces high charged-state heterogeneity compared to slow charge. Tests on aged cells indicate that heterogeneity will equilibrate during months long storage, but will regenerate at a higher magnitude at faster charge (9C) compared to slower charge (1C). The influence of outgassing on cell performance was tracked by mapping a freshly constructed cell during its first formation cycle at C/10-C/10 charge-discharge rate. Solid electrolyte interphase byproduct gas “bubbles” were discovered based on their hindrance on lithiation-induced crystallographic changes and were randomly interspersed throughout the cell, indicating that outgassing creates “dead” zones within electrodes and impedes proper SEI development during the formation process. The results reveal that electrode architectures and charging protocols that promote homogeneous charge distribution are critical for high-performance long-life cells.