Method and system for life extension of battery cell

A method for extending life of a battery cell provided with charge/discharge terminals to which a charging voltage can be applied with a flowing charging current, the method comprising:

• applying, to the terminals of the battery cell, a plurality of constant voltage stages Vj, where Vj+1>Vj, j=1, 2 . . . , k, each voltage stage comprising intermittent nj voltage plateaus;
• between two successive voltage plateaus within a voltage stage, letting the charging current go to zero for a rest period Rjp, 1≤p≤nj, until any one of the following conditions is reached:
• a pre-set charge capacity or state of charge (SOC) is reached,
• the battery cell temperature exceeds a pre-set limit value Tlim, or
• the battery cell voltage has exceeded a pre-set limit value Vlim;
• collecting data on at least two previous measured discharge capacities;
• calculating a relative variation (ΔQ/Q) of the discharge capacity, from the collected data;
• comparing the calculated relative variation (ΔQ/Q) of the discharge capacity to a predetermined threshold (ε);
• and
• if the calculated relative variation (ΔQ/Q) of the discharge capacity exceeds the predetermined threshold (ε), modifying at least one charge parameter among a selection of charge parameters including a duration of the voltage plateau, the voltage stage shift, and the rest time, so as to bring the calculated relative capacity variation (ΔQ/Q) below the predetermined threshold (ε).