Composite electrolyte for pre-lithiation of lithium battery and application of composite electrolyte

Abstract

The invention discloses a composite electrolyte for pre-lithiation of a lithium battery and an application of the composite electrolyte. The composite electrolyte comprises an electrolyte; an additiveis added into the electrolyte; and the additive can be decomposed into lithium ions, electrons and gas under a voltage condition of 1-3V. After a battery cell is formed, the lithium ions generated bydecomposition of the additive can be used for supplementing lithium ions consumed for generating an SEI film in a battery system, meanwhile the gas generated by decomposition can be exhausted by a normal exhaust process after formation, and the battery cell is not influenced, so that the purpose of the pre-lithiation of the battery is achieved. The direct use of lithium metal is avoided, and thepotential safety hazards caused by the lithium metal are reduced. In addition, the added lithium ions are generated by the decomposition of the additive dissolved in the system and can be fully dispersed in the electrolyte, and the pre-lithiation amount can be accurately controlled through the usage amount of the additive, so that the purpose of accurate and uniform pre-lithiation can be achieved,and the cycling performance and the first coulombic efficiency of the battery can be obviously improved.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a composite electrolyte solution for pre-lithiation of lithium batteries and an application thereof. Background technique [0002] Due to the advantages of high voltage, high energy density and long cycle life, lithium-ion batteries have become one of the most widely used secondary batteries. Lithium-ion batteries are currently the battery system with the highest energy density among commercial secondary batteries. Commercial lithium-ion batteries have good cycleability and safety in use. They have been widely used in communications, transportation, electronic equipment, and industrial products. , and quickly obtain a larger market. However, with the miniaturization of portable electronic products, the demand for long standby time, and the application and development of high-power and high-energy devices such as electric tools and electric vehicles, the...

AI Technical Summary

Problems solved by technology

Although this method can also play the role of pre-lithiation of the negative electrode sheet, the thickness of the lithium sheet currently available on the market is about 45um, which is far beyond the amount that the negative electrode can absorb. Not only is there too much lithium metal in the battery There are potential safety hazards, and it is also easy to cause lithium precipitation in the cycle

[0007] In addition, the Japanese patent application of JP2005038720 deposits a metal lithium layer on the surface of the negative electrode by vacuum evaporation. Although the thickness of the lithium layer can be controlled, it needs to be carried out in a strict vacuum environment during the whole process. The efficiency of evaporation is also low, and the transfer of subsequent pole pieces needs to prevent nitriding and oxidation, so the process is more complicated and the cost is extremely high

[0008] In view of the above analysis, although the method of adding metal lithium powder and lithium foil to the lithium-ion battery can obviously improve the first-time efficiency of the battery, improve the cycle, etc., and has been verified experimentally, it has not been widely promoted.

In addition to the influence of its own safety performance and price, the environmental restrictions and safety factors in the use process are also a major reason for restricting its promotion.

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