Abstract: Provided is a lithium iron phosphate battery, comprising a positive electrode, a negative electrode and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode material layer with a compacted density of 2.3-2.8 g/cc, and the positive electrode material layer comprises a positive electrode active material, the positive electrode active material comprises LiFePO4; the non-aqueous electrolyte comprises a solvent, an electrolyte salt, vinylene carbonate and a compound represented by Structural formula 1; an addition amount of the compound represented by Structural formula 1 is 0.01-5% based on a total mass of the non-aqueous electrolyte being 100%.

Abstract: The present application provides a secondary battery, including a positive electrode, a negative electrode with a negative electrode material layer, and a non-aqueous electrolyte, the negative electrode material layer comprises a negative electrode active material, and the negative electrode active material comprises a silicon-based material; the non-aqueous electrolyte comprises a solvent, an electrolyte salt and an additive, the additives comprises a compound represented by structural formula 1; wherein n is 0 or 1, A is selected from C or O, X is selected from R1 and R2 are each independently selected from H, R1 and R2 are not selected from H at the same time, and X, R1 and R2 comprise at least one sulfur atom; the secondary battery meets the following requirements: 0 . 2 ? 1 ? m * n * r S ? 40 ; and 40%?m?90%, 0.05%?n?2%, 1.2 g/cm3?r?1.8 g/cm3, 5%?S?30%.

Abstract: A method of preparing a modified polyvinyl acetate includes subjecting a mixed liquor L1 containing a functional monomer to a first reaction with a first vinyl acetate monomer, followed by adding a first initiator to carry out a second reaction to obtain a mixed liquor L2; subjecting an acrylate monomer, a second vinyl acetate monomer, a second initiator and the mixed liquor L2 to carry out a third reaction to obtain a mixed liquor L3; and subjecting a third initiator and the mixed liquor L3 to carry out a fourth reaction under the air-tight and ultrasonic conditions. The functional monomer is selected from acrylic acid, oleic acid or butenedioic acid. Uses of modified polyvinyl acetate obtained by the method and oil-based drilling fluid containing the modified polyvinyl acetate are also disclosed.