NOVELTY - An electrolyte composition comprises: aprotic organic solvent, lithium alkoxyborates compound (I), at least one conducting salt different from the compound (I), and optionally, at least one further additive.    USE - As electrolyte composition in lithium ion batteries (claimed). Also used in electrochemical cell for vehicles (e.g. automobiles, bicycles, aircraft, or water vehicles such as boats or ships), computers (such as laptops), telephones and electrical power tools e.g. construction sector, especially drills, battery-driven screwdrivers or battery-driven staplers.    ADVANTAGE - The lithium alkoxyborates (I) as electrolyte additives in electrolyte composition for lithium ion batteries enhance the long time stability and the thermal stability of the electrolyte composition and of the lithium ion battery. It allows using the electrolyte composition and the lithium ion battery in a broader temperature range. In particular, the additives should be provided which improve the performance of the electrolyte to high voltage (4.5 V vs Li/Li+) especially at elevated temperature (greater than 45 degrees C).    DETAILED DESCRIPTION - An electrolyte composition comprises: aprotic organic solvent, lithium alkoxyborates compound of formula (I), at least one conducting salt different from the compound (I), and optionally, at least one further additive.    R1-R4=1-10C alkyl, 2-10C alkenyl, 2-10C alkynyl, 3-10C cycloalkyl, 6-14C aryl or 5-14C heteroaryl (all optionally substituted by F, CN, OR5, group of formula (ia), and optionally fluorinated groups selected from 1-4C alkyl, 2-4C alkenyl, 2-4C alkynyl, phenyl, and benzyl);    R5=H, oligo 1-4C alkylene oxide with 2 to 10 alkylene oxide units, and optionally fluorinated groups selected from 1-4C alkyl, 2-4C alkenyl, 2-4C alkynyl, phenyl, benzyl, or C(O)O(1-10C) alkyl;    R6=H, F and optionally fluorinated 1-4C alkyl.    The R4 is different from each R1, R2, and R3. An INDEPENDENT CLAIM is included for a lithium ion battery comprising the electrolyte composition, at least one cathode comprising a cathode active material, and at least one anode comprising an anode active material.