The electrolyte additive includes a neutral compound represented by formula (1) and having, in the molecule, a trialkyl silyl group. It can improve the withstand voltage of the electrolyte and be applied to electrolyte for lithium-ion rechargeable batteries. In formula (1), R1 each represent independent C1-8 alkyl groups, R2 each represent independent C1-8 alkyl groups, A represents a C1-10 alkylene group, X represents either a single bond, a methylene group or one of the linking groups represented by formulas (2) to (4), m represents an integer from 1 to 3, n represents an integer from 0 to 2, where m+n is 2 if X is a single bond, a methylene group, a linking group represented by formula (2) or a linking group represented by formula (3), and m+n is 3 if X is a linking group represented by formula (4). In formula (3), R3 represents a C1-8 alkyl group.