Method for constructing LiF protection layer on three-dimensional lithium-carbon composite material and application of LiF protection layer

Abstract

The invention provides a method for constructing a LiF protection layer on a three-dimensional lithium-carbon composite material. The method comprises the following steps: mixing graphene, a fluorine-containing organic binder solution and metal lithium powder to obtain metal lithium / graphene composite material slurry; coating a current collector with the metal lithium / graphene composite material slurry to obtain an electrode; and carrying out thermal lithiation compounding on the electrode to obtain a LiF protection layer in a three-dimensional size. Different from other methods for introducing a fluorine-containing protection layer on the surface of a blocky lithium foil lithium sheet through additional reaction steps in the prior art, the method provided by the invention is used for synthesizing the lithium metal powder / graphene three-dimensional composite negative electrode material with LiF protection through a one-step method of homogenate coating, heating and compounding without complicated devices and equipment, is simple and time-saving and can be used for large-area production. The invention also provides an application of constructing the LiF protection layer on the three-dimensional lithium-carbon composite material.

Description

technical field [0001] The invention belongs to the technical field of electrodes, and in particular relates to a method for constructing a fluorine-rich protective layer on the surface of lithium metal powder and an application thereof. Background technique [0002] The solid electrolyte film (SEI) formed by the reaction of the traditional lithium metal negative electrode with the electrolyte is fragile, and it is easy to rupture due to the volume expansion caused by lithium deposition during repeated charge-discharge cycles, exposing the new lithium underneath to continue to react with the electrolyte, so Repetition will lead to continuous irreversible loss of active materials and electrolytes and accumulation of "dead lithium" that is not electrochemically active on the surface of the lithium negative electrode, increasing the internal resistance of the battery and reducing the battery capacity. [0003] A common method to improve the lithium metal negative electrode is t...

AI Technical Summary

Problems solved by technology

[0005] In the existing technology, the introduction of fluorine-containing substances is aimed at modifying the lithium metal negative electrode. There are limitations such as cumbersome preparation process and difficulty in large-scale preparation, which limits the application of these technologies in actual battery systems.

For example, some require special heating and melting liquefaction spray devices, hot pressing devices, etc., and require inert atmosphere protection. Strict equipment requirements make the preparation process complicated and have extremely high safety requirements, and the obtained protective layer has poor uniformity and passivation effect. High cost of manpower and material resources

Some technologies need to prepare the passivation layer by solid-liquid reaction. Due to the limitation of the objective conditions of the reaction, this type of technology cannot be prepared in large-scale batches, and the quality of the protective layer is very dependent on the chemical reaction raw materials and reaction time. Polishing the sheet to remove surface impurities is helpful for the reaction to proceed. After the reaction, repeated cleaning is required to remove the residual solution. The operation is cumbersome, time-consuming and labor-intensive.

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