Modified composite material containing silicon-base material, preparation method thereof, and application thereof in lithium ion battery

Abstract

The invention discloses a modified composite material containing silicon-base material, a preparation method thereof, and an application thereof in a lithium ion battery. The composite material includes a silicon-base core and a modifying layer covering same. The modifying layer includes a polymer covering film and a nano-conductive material embedded therein. The modified composite material not only can isolate an electrolyte to inhibit side reactions of the electrolyte on the surface of the material, thus improving overall performance of the battery, but also can improve electric conductivityand improve structural stability due to the unique structure by embedding the nano-conductive material in the polymer. Tension is absorbed by means of deformation, so that problems of breaking and pulverization and stripping of the electrode during processing and use of the silicon-base negative material are solved. The problems of pulverization and stripping of the electrode due to large expansion during charge / discharge processes of the silicon-base material are solved, thus stabilizing the structure of the electrode and improving cycle performance of the cell.

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.

Moreover, the method of carbon coating by high-temperature calcination of carbon sources in the prior art has the problems of high energy consumption and low production efficiency.