A non-aqueous electrolyte for a rechargeable electrochemical cell and non-aqueous electrolyte rechargeable electrochemical cell

It is the aim of the present invention to retain the benefits of a lithium ion cell capable of operating at temperatures down to as low as about -40 DEG C while minimizing the permanent cycle capacity loss under the circumstance of establishing the first cycle irreversible capacity loss at a tolerable level. This aim is achieved by a non-aqueous electrolyte for a rechargeable electrochemical cell, comprising a) a film forming organic component; b) an alkali metal salt; and c) as an additive a nitrogen-containing hetero-aromate and/or its derivatives and/or mixtures thereof; and/or d) as an additive a compound selected from a group containing aniline, pyrrole, 2-methyl-1-pyrroline, 1-methylpyrroline and 1-vinyle-2-pyrrolidine. Surprisingly, these additives have the properties of supporting the immediate generation of superior solid electrolyte interphases on the carbon/graphite anode in order to suppress its exfoliation when propylene carbonate is used as a main organic compound. Depending on the choice for the anode material which significantly has an impact on the irreversible first cycle capacity loss, an electrochemical cell equipped with this electrolyte maintains its capacity over a comparably high number of charge/discharge cycles with capacity losses far below 0.5% per cycle.