A dynamic formation protocol for a lithium-ion battery cell. An “SEI formation end voltage” is identified, which is the voltage reached during formation at which the SEI layer is substantially formed. Charge rates are selected for the formation, with a first charge current rate to be used until the SEI formation end voltage is reached, and a second charge current rate, faster than the first charge current rate, to be used thereafter the SEI formation end voltage. These charge rates are applied to the cell for at least a first cycle of the dynamic formation process.