Modified composite material containing silicon-based material, preparation method thereof and use thereof in lithium ion battery

Abstract

The invention discloses a modified composite material containing a silicon base material, which comprises a silicon base core and a polymer cladding layer covering the surface of the core, and a preparation method and use thereof in a lithium ion battery. The method comprises the steps of : 1) adding a polymer into a liquid solvent and dispersing to obtain a slurry; 2) adding a silicon-based material or a mixture of that silicon-based material and the carbon material into the slurry and mixing the solid and liquid; 3) removing the solvent to obtain a modified composite material containing a silicon-based material. As the polymer coat layer is introduced on the surface of the silicon base core, so that the electrolyte can be isolated and the side reaction of the electrolyte on the surface of the silicon base core can be prevented; the method can also improve the crushing, electrode pulverization and peeling of the silicon-based negative electrode material in the process of processing and using, and reduce the electrode crushing and peeling caused by the huge volume expansion of the silicon-based material in the process of charging and discharging, so as to achieve the purpose of stabilizing the electrode structure and improving the cell cycle performance.

Description

technical field [0001] The invention belongs to the technical field of lithium ion batteries, and relates to a modified composite material containing silicon-based materials, a preparation method thereof and an application in lithium ion batteries. Background technique [0002] Due to its high energy density, high voltage and environmental friendliness, lithium-ion batteries are widely used in portable power devices (such as mobile phones, computers) and electric vehicles. However, due to the influence of battery materials, conductive additives, and binders, it is currently difficult to prepare lithium-ion batteries with high reversible capacity, high cycle stability, and high rate performance. [0003] Anode materials are very important components of lithium-ion batteries, which directly affect the energy density and electrochemical performance of lithium-ion batteries. Excellent negative electrode materials can improve the reversible capacity, cycle performance, and rate ...

AI Technical Summary

Problems solved by technology

For example, CN 104112847A discloses a silicon-based negative electrode material and its method. The silicon-based negative electrode material includes: carbon tubes and nano-silicon particles located inside the carbon tubes. Since the carbon tubes have voids inside, the silicon particles can be fixed on the In the limited space in the carbon tube, the volume expansion or contraction of the silicon particles is within the limited space, which not only avoids affecting the electron transport performance between the active material and the current collector, but also avoids the thickening of the SEI film, which is beneficial to Improve the capacity and performance of lithium batteries. However, carbon tubes lack ductility and cannot effectively absorb the tension generated by volume expansion during electrode charging and discharging, so they cannot prevent the pulverization of delayed particles.

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