Organic electrolyte capable of improving low-temperature performance of lithium manganese battery

Abstract

The invention discloses organic electrolyte capable of improving low-temperature performance of a lithium manganese battery. A main salt of a lithium salt is lithium perchlorate, an auxiliary salt of the lithium salt is selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium bis(oxalate) borate,lithium bis(trifluoromethanesulphonyl)imide, lithium bis(fluorosulfonyl)imide, lithium oxalyldifluoroborate and lithium iodide; an organic solvent is a mixed solvent of cyclic esters, linear esters, ethers and sulfones; an additive is selected from an additive A and an additive B, wherein the additive A is selected from benzoic acid, phenylacetic acid, benzoic anhydride, phthalic anhydride, m-phthalic anhydride and terephthalic anhydride, and the additive B is selected from 2,6-di-tert-butyl-4-methylphenol, tert-butylhydroquinone and butylated hydroxyanisole. By adopting the organic electrolyte, the low-temperature discharging performance of the lithium manganese battery can be obviously improved, and the application range of the lithium manganese battery can be effectively enlarged.

Description

technical field [0001] The invention relates to a lithium battery electrolyte, which belongs to the field of electrochemistry, and specifically refers to a lithium-manganese primary battery electrolyte with good low-temperature performance. Background technique [0002] With the rapid development of electronic information technology and consumer electronics, the performance requirements for batteries are also rapidly increasing, especially the low-temperature discharge performance of batteries, which has become a key technology encountered in the expansion of lithium-manganese batteries. Difficulties, most of the solvents in commercial lithium-manganese battery electrolytes are organic cyclic carbonates and organic ether systems. Except for 1,3-dioxolane, which has a low melting point of -95°C, the melting points of other organic solvents are higher than - 50°C, when the ambient temperature is lower than -20°C, the viscosity of the electrolyte increases exponentially, part o...

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Problems solved by technology

[0002] With the rapid development of electronic information technology and consumer electronics, the performance requirements for batteries are also rapidly increasing, especially the low-temperature discharge performance of batteries, which has become a key technology encountered in the expansion of lithium-manganese batteries. Difficulties, most of the solvents in commercial lithium-manganese battery electrolytes are organic cyclic carbonates and organic ether systems. Except for 1,3-dioxolane, which has a low melting point of -95°C, the melting points of other organic solvents are higher than - 50°C, when the ambient temperature is lower than -20°C, the viscosity of the electrolyte increases exponentially, part of the lithium salt crystallizes out, and the conductivity decreases significantly. Drop to 2.1 ~ 2.3V, because the voltage platform is too close to the discharge cut-off voltage of lithium manganese battery 2.0V, the discharge time and capacity of lithium manganese battery are also significantly reduced, which greatly limits the use of lithium manganese battery in low temperature environment. usage of

[0003] The "A Lithium Battery Electrolyte and Its Preparation Method" disclosed in the patent literature with the Chinese patent application number CN94114864.5, which has better low-temperature performance, belongs to the method of using cyclic ethers, and the organic solvent of the lithium battery electrolyte is composed of ethylene di Alcohol dimethyl ether, 1,2-propanediol carbonate, and compound cyclic ethers are combined. It is found in practical application that the preparation process of this complex cyclic ether is complicated, the purification and separation of the product is difficult, the production cost is high, and the proportion of each component of the complex cyclic ether cannot be precisely controlled, so it is difficult to realize large-scale continuous industrial production

[0004] In the low-temperature electrolyte patents for lithium-ion batteries, many mention the use of fluorine-containing cyclic carbonates to improve the low-temperature performance of the electrolyte, but there are two major disadvantages in the application of fluorine-containing cyclic carbonates in lithium-manganese batteries. 1) Since the dielectric constant of fluorine-containing cyclic carbonates is lower than that of fluorine-free cyclic carbonates, it is necessary to increase the dosage to make up for the lack of conductivity. Due to the high viscosity of fluorine-containing cyclic carbonates, adding a large amount will cause The overall viscosity of the electrolyte increases, but the low-temperature conductivity decreases, which does not help the low-temperature discharge performance; 2) The synthesis of fluorine-containing cyclic carbonate is relatively difficult, and there is no mass production at present, and its price is high, which is difficult to apply in lithium manganese battery electrolyte