Lithium ion battery comprising electrolyte solutions with improved safety and storage performance

Abstract

The invention discloses a lithium ion battery comprising electrolyte solutions with improved safety and storage performance. The lithium ion battery comprises conventional electrolyte solutions which comprise electrolyte salt, organic solvents and conventional additives. The electrolyte salt comprises solid solute LiPF6, the organic solvents comprise EC, DMC and EMC, and the conventional additives comprise VC and FEC. Overcharge additives and function additives are further added in the conventional electrolyte solutions. The overcharge additives comprise at least one of biphenyl, terphenyl and phenylcyclohexane, and the function additives comprise succinonitrile or adiponitrile. According to the lithium ion battery comprising the electrolyte solutions with improved safety and storage performance, the electrolyte solutions can prevent a lithium ion battery from being overcharged, and meanwhile the side reaction of the overcharge additives within the normal charging voltage range of a battery is restrained.

Description

technical field [0001] The invention relates to the technical field of batteries, in particular to a lithium-ion battery containing an electrolyte with improved safety and storage performance. Background technique [0002] At present, lithium-ion batteries have the advantages of high specific energy, many cycle times, and long storage time. They are not only widely used in portable electronic devices such as mobile phones, digital cameras, and laptop computers, but also widely used in electric vehicles and electric bicycles. And large and medium-sized electric equipment such as electric tools. [0003] For lithium-ion batteries, during the charging process, lithium ions come out of the positive electrode and enter the negative electrode through the electrolyte. Lithium-ion batteries have a normal operating voltage range, generally between 2.0V~4.35V. When charging, it should not exceed The highest charging voltage for Li-ion. Lithium-ion battery chargers or protection cir...

AI Technical Summary

Problems solved by technology

Lithium-ion battery chargers or protection circuits have the function of protecting the battery charging voltage from being lower than the maximum charging voltage. However, when the charger and protection circuit fail, the battery will be overcharged if the battery continues to be charged, and the lithium in the positive electrode material will be released in excess. , leading to a decrease in the thermal stability of the positive electrode material. As the battery voltage increases, the electrolyte oxidizes and decomposes on the surface of the positive electrode, releasing heat, and the temperature of the battery rises, which in turn promotes the thermal decomposition of the electrolyte, positive electrode, and negative electrode. reaction, which will eventually lead to thermal runaway of the battery

Therefore, it is currently necessary to add additives to the electrolyte of lithium-ion batteries to prevent safe failure of lithium-ion batteries due to overcharging

[0004] However, due to the uneven local current of the positive electrode during the charging process of the lithium-ion battery, the local potential is higher than the maximum normal charging voltage of the lithium-ion battery, causing side reactions to occur in the overcharge additive during normal charging and discharging, especially for the oxidation potential Lower overcharge additives such as biphenyl, pyrrole, indole, thiophene, furan and other overcharge additives, these overcharge additives produce side reaction products within the normal operating voltage range of the battery, which will cause the battery to automatically The larger the discharge, the greater the internal resistance.

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