Modified silicon negative electrode material for lithium ion battery and preparation method and application thereof

Abstract

The invention discloses a preparation method for a modified silicon negative electrode material for a lithium ion battery and a product and application. The preparation method comprises the followingsteps of: (1) carrying out surface modification on nano silicon particles to obtain nano silicon particles with hydroxyl on the surfaces, (2) dispersing the nano silicon particles with hydroxyl on thesurfaces prepared in the step (1) into water, conducting mixing with an alkoxy silane / ethanol solution, and performing dehydration reaction to obtain a modified silicon negative electrode material. The general formula of alkoxy silane is R1-Si-(OR2)3, in the formula, R1 is selected from alkyl with the carbon number of 1 to 18, and R2 is selected from methyl or ethyl. The mass ratio of the nano silicon particles with hydroxyl on the surfaces to the alkoxy silane is 1000 to (1-10). According to the preparation method for the modified silicon negative electrode material for the lithium ion battery disclosed in the invention, the prepared modified silicon negative electrode material has excellent initial specific capacity, initial coulombic efficiency and cycling stability, and is expected tobe more widely applied to the field of lithium ion batteries.

Description

technical field [0001] The invention relates to the technical field of electrode materials, in particular to a modified silicon negative electrode material for a lithium-ion battery and a preparation method and application thereof. Background technique [0002] At present, the development of electric vehicles has higher and higher requirements for the battery life of lithium-ion batteries. Research on a new generation of high-energy-density lithium-ion batteries has become a top priority for the development of the electric vehicle industry. However, due to its low theoretical capacity (374mAh.g -1 ) has gradually been unable to meet the requirements of the field of electric vehicles, therefore, a new generation of lithium-ion battery anode materials with high theoretical capacity has become a current research hotspot. [0003] Silicon materials are considered to be the most promising alternatives to carbon as anode materials for next-generation lithium-ion batteries. As th...

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Problems solved by technology

However, since the silicon material faces a volume change of 300% in the process of deintercalating lithium, it is easy to cause the following problems: (1) the silicon material itself is pulverized and loses most of its effective mass; (2) it loses electrical contact with the current collector (3) The solid electrolyte interface (SEI) film is always in a state of dynamic destruction-reconstruction, which will cause continuous lithium consumption and eventually lead to the attenuation of battery capacity

However, since the surface of the modified silicon anode material contains specific functional groups, the slurry preparation process after synthesizing the corresponding surface-modified silicon anode has a certain selectivity for the slurry, and current commonly used materials such as PVDF cannot be used. binder

In addition, the binder is not controllable when bonding with surface groups to form an organic film, and has limited influence on the destruction-reconstruction process of the SEI film.

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