Increased polarization also explains the gradual decline of the relative capacity below 0.35 V that is observed past cycle 65 in Figure for CCCV cycling. The larger SEI build-up can also be observed by comparing coulombic efficiency with and without the constant voltage step (Figure ). Initial coulombic efficiency is similar with and without a constant voltage step, but after increasing the rate to 600 mA/g, the coulombic efficiency remains lower with a constant voltage step as more reaction with the electrolyte occurs at low voltages. under a CCCV protocol and remaining for the most part amorphous with a CC protocol.