Preparation method of sei film on surface of lithium battery electrode material and film-containing electrode material

Abstract

The invention discloses a method for preparing an SEI film on the surface of a lithium battery electrode material and an electrode material containing the SEI film. The preparation method comprises: uniformly dispersing the electrode material of a lithium ion battery in an organic solvent containing a strong reducing agent, stirring and solidifying The modified electrode material is obtained by liquid separation; the modified electrode material is uniformly dispersed in a fluorocarbonate organic solvent, and the solid-liquid separation is performed after stirring; the product of the solid-liquid separation is rinsed and dried. Compared with the traditional method of chemical formation and charging to form an SEI film, the method of the present invention uses a chemical reaction method to form an SEI film on the surface of the electrode material, which is easier to optimize and control the morphology and structure of the SEI film of the lithium-ion battery through the control of the reaction process conditions, and The method is simple and convenient to operate, and is not limited by the redox potential characteristics of the electrode material itself. In addition, this method can effectively save the time required for the production of traditional lithium-ion batteries, and effectively improve the initial charge-discharge efficiency and long-term cycle stability of lithium-ion batteries.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a method for preparing an SEI film on the surface of a lithium battery electrode material and an electrode material containing the SEI film. Background technique [0002] Due to the advantages of high energy density, excellent rate and power performance, long cycle life, safety and environmental protection, lithium-ion batteries are widely used in our daily life as an important chemical power source. The current commercially produced lithium-ion batteries are generally composed of positive electrodes, negative electrodes, separators, and electrolytes. The electrolytes can form a stable SEI film on the surface of electrode materials, especially the surface of negative electrode materials, during the first formation and charging process. The SEI film can prevent the contact between the electrolyte and the surface of the electrode material, and inhibit the side reactio...

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Problems solved by technology

However, the disadvantages of this kind of SEI film preparation method are also very obvious. On the one hand, because the electrolyte usually contains a variety of lithium salts, additives and solvents, the components are very complicated. The formation mechanism is also difficult to define clearly. Therefore, the formation of the SEI film in the chemical formation process is affected by many uncontrollable factors. Researchers can only optimize and regulate it through a large number of trial and error experiments. The controllable SEI film construction method is still A research difficulty in this field; on the other hand, it takes a long time to prepare the SEI film by using the chemical formation charging method, and whether the SEI film can be formed is limited by the relative potential between the electrode material and the electrolyte, and the formation of the SEI film for the first time Part of the active lithium will be consumed, resulting in irreversible capacity loss

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