Studies on the anode/electrolyte interface in lithium ion batteries

Rechargeable lithium ion cells operate at voltages of 3.5-1.5 V, which is f ar beyond the thermodynamic stability window of the battery electrolyte. St rong electrolyte reduction and anode corrosion has to be anticipated, leadi ng to irreversible loss of electroactive material and electrolyte and thus strongly deteriorating cell performance. To minimize these reactions, anode and electrolyte components have to be combined that induce the electrolyte reduction products to form an effectively protecting film at the anode/ele ctrolyte interface, which hinders further electrolyte decomposition reactio ns, but acts as membrane for the lithium cations, i.e. behaving as a solid electrolyte interphase (SEI). This paper focuses on important aspects of th e SEI. By using key examples, the effects of film forming electrolyte addit ives and the change of the active anode material from carbons to lithium st orage alloys are highlighted.