ELECTROLYTE ADDITIVE, BATTERY ELECTROLYTE COMPRISING SAME, AND SECONDARY BATTERY COMPRISING SAME

[ABSTRACT]The present invention relates to an electrolyte additive, an electrolyte for batteries including the electrolyte additive, and a secondary battery including the electrolyte. More particularly, the present invention relates to an electrolyte additive including a compound containing a substituent represented by Chemical Formula 1, an electrolyte including the electrolyte additive, and a secondary battery including the electrolyte.According to the present invention, the present invention has an effect of providing a secondary battery having improved charging efficiency and output due to low charge resistance, having a long lifespan, and having excellent capacity retention at high temperatures.In Chemical Formula 1, P and O are phosphorus and oxygen, respectively; A is a bond or oxygen; Q is oxygen or an unshared electron pair; R1, R2, R3, and R4 are each independently hydrogen, a linear or branched alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxyalkyl group, a fluoroalkyl, or a cyclic sulfate; optionally, R1 or R2 is connected to R3 or R4 to form a double bond or a ring; n is an integer from 0 to 3; and * is a binding position.