All-weather high-rate lithium battery electrolyte and lithium ion battery

Abstract

The invention provides an all-weather high-rate lithium battery electrolyte and a lithium ion battery. The lithium battery electrolyte comprises a lithium salt electrolyte, an organic solvent and an additive, wherein the freezing point of the organic solvent is-150--20 DEG C; and the additive is one or more of lithium nitrate, lithium perchlorate, lithium sulfate and lithium carbonate, and the mass content of the additive in the lithium battery electrolyte is 0.1-10%. The electrolyte provided by the invention is low in melting point of each component, small in viscosity and high in conductivity, and still keeps relatively high conductivity at a low temperature of -100 DEG C to -60 DEG C, so that the cycle performance of the ternary lithium battery under an extremely low temperature condition is greatly improved. In addition, the oxidation resistance of the electrolyte can be greatly improved, the electrochemical window of the electrolyte is widened, and a stable SEI film is formed, so that the electrolyte can adapt to efficient operation of a ternary positive electrode material at a high voltage of 4.2-4.5 V.

Description

technical field [0001] The invention relates to the technical field of electrochemistry, in particular to an all-weather high-rate lithium battery electrolyte and a lithium ion battery. Background technique [0002] As a device capable of storing and continuously providing electrical energy, batteries continue to meet people's needs for flexible use of electricity. Among many battery systems, lithium-ion batteries have been widely recognized by the market due to their excellent performance. Since Japan's SONY company commercialized them in 1991, they have been widely used in consumer electronics, new energy vehicles and energy storage fields, and have become the most popular products for various products. Indispensable and important components. [0003] However, lithium-ion batteries based on commercial carbonate electrolytes have problems such as a drop in discharge voltage plateau, low discharge capacity, fast capacity decay, and poor rate performance in a low-temperature...

AI Technical Summary

Problems solved by technology

It has been reported in the literature that liquefied gas is used instead of electrolyte, so that lithium batteries can maintain high-efficiency operation at -60°C, but the battery performance at room temperature still needs to be improved, and special high-pressure containers are required to keep liquefied gas in a liquid state

There are also reports in the literature that the use of fluorine-containing electrolytes to dissolve into highly fluorinated non-polar solvents to reduce the affinity between the solvent and lithium ions, the electrolyte has a high charge in a wide voltage range (0.0-5.6V). Chemical stability, and even at a low temperature of -85°C, LiNi 0.8 co 0.15 Al 0.05 o 2 ||Li batteries can still provide about 50% room temperature capacity; but the conductivity of the electrolyte system is low at low temperatures (-80°C, 0.011mS cm -1 ), the long-term cycle performance at ultra-low temperature is unknown, and highly fluorinated solvents are usually highly toxic and expensive, not suitable for large-scale production and application

CN103078141A discloses a lithium-ion secondary battery electrolyte, including solvent and lithium salt, and also includes film-forming additives. The technical solution uses a combination of linear carboxylate and ethylene carbonate to obtain a high dielectric constant and low-viscosity solvent system , but its capacity retention rate at -20°C is only 40%-45%, the low temperature performance is not very ideal, and it cannot meet the use requirements under low temperature conditions

CN 108270033A reduces the interface impedance of the electrolyte and improves the low temperature of the lithium-ion battery by adding functional additives fluoroethylene carbonate and propenyl-1,3-propane sultone to the LiBOB and LiODFB lithium salt systems performance, although the battery performance of this solution has been improved under general low-temperature environmental conditions, it still cannot solve the problem of low conductivity of lithium salts under ultra-low temperature conditions of -50°C

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