▎ 摘　　要

NOVELTY - Cathode sheet comprises a cathode material layer including a cathode active material comprising carbon-based material and phosphate compound (I). The cathode sheet satisfies that 10*c*a/b is 0.2-40, the resistivity of the cathode sheet is ≤ 200 Ω.m, the liquid chromatography-mass spectrometry (LC-MS) analysis of the solution obtained after the cathode sheet is ultrasonically oscillated in the solvent shows that the characteristic peak appears in the region with a retention time of 6.5-7.5 minutes. USE - The cathode sheet is useful in secondary batteries (claimed). ADVANTAGE - The cathode sheet: overcomes the problems of insufficient SEI film stability in existing lithium-ion batteries that lead to battery cycle performance degradation and capacity fading, used in secondary battery; has low impedance, can improve the permeability of the non-aqueous electrolyte to the cathode material layer, and efficiently improve the cycle performance of the battery. DETAILED DESCRIPTION - Cathode sheet comprises a cathode material layer including a cathode active material comprising carbon-based material and phosphate compound of formula (I). The cathode sheet satisfies that 10*c*a/b is 0.2-40, the resistivity of the cathode sheet is ≤ 200 Ω.m, the liquid chromatography-mass spectrometry (LC-MS) analysis of the solution obtained after the cathode sheet is ultrasonically oscillated in the solvent shows that the characteristic peak appears in the region with a retention time of 6.5-7.5 minutes, c is mass percentage of the cathode active material in the cathode material layer, the unit is %; a is mass percentage of the compound I in the cathode material layer in %; and b is porosity of the cathode material layer in %. Either R1-R3= 1-5C alkyl group, 1-5C fluoroalkyl group, 1-5C ether groups, 1-5 fluoroether group or 2-5 C unsaturated hydrocarbon group; Or at least one of R1-R3= 2-5C unsaturated hydrocarbon group; a = 0.005-1; b = 10-50; and c = 92-98. An INDEPENDENT CLAIM is also included for secondary battery comprising an anode sheet, a non-aqueous electrolyte and the cathode sheet.