Secondary Battery Including Electrolyte Additive

A secondary battery comprising an electrode assembly comprising a cathode, an anode and a separator interposed therebetween, and an electrolyte,

• wherein the anode comprises lithium titanium oxide (LTO) as an anode active material, and
• wherein the electrolyte is a gel polymer electrolyte, which contains a phosphate-based compound as an additive, wherein the phosphate-based compound comprises at least one selected from the group consisting of a phosphate-based acrylate of Formula (1), a pyrophosphate-based acrylate of Formula (2) and a phosphate-based urethane acrylate:
• where R1 and R2 are each independently hydrogen, methyl or F, and n is an integer of 1 to 20.