Memory effect highlighting in silicon anodes for high energy density lithium-ion batteries

A memory effect occurring on silicon electrodes during lithium insertion/deinsertion was revealed by means of electrochemical characterizations. The reversible capacity fading is triggered when the electrodes are cycled between Li-rich compositions, which are actually achieved in selected conditions (current density, voltage window, electrode thickness). It is correlated with a structural evolution of Li-rich alloys, i.e. the crystallization of Li15Si4 or the probable ordering of other Li-rich phases. It should be avoided in Li-ion practical cells by an appropriate cell design.

► A memory effect occurs in silicon electrodes during lithium insertion/deinsertion. ► The capacity fading triggered in a specific voltage window is fully reversible. ► The capacity fading is linked to the formation of Li-rich lithium–silicon alloys. ► The LixSi voltage curve is modified due to the ordering of Li-rich phases.