The present invention relates to a composition for a cathode active material layer for a lithium secondary battery, and a cathode, a lithium secondary battery, a battery module and a battery pack which comprise same, the composition comprising an additive represented by chemical formula A and a cathode active material, which comprises a single-particle-form lithium composite transition metal compound comprising: nickel in an amount greater than or equal to 80 mol% and less than 100 mol% on the basis of the amount of metals excluding lithium; cobalt; and manganese.