Deliberate modification of the solid electrolyte interphase (SEI) during lithiation of magnetite, Fe3O4: impact on electrochemistry.

Magnetite is a conversion anode material displaying multi-electron transfer during lithiation and delithiation. The solid electrolyte interphase (SEI) on magnetite, Fe3O4, electrodes for lithium ion batteries was deliberately modified through the use of fluoroethylene carbonate (FEC) electrolyte additive, improving both capacity retention and rate capability. Analysis showed reduction of FEC at higher voltage compared to non-fluorinated solvents with formation of a modified lithium flouride containing electrode surface.