A kind of preparation method of high first-efficiency lithium-ion secondary battery negative electrode active material

Abstract

The invention relates to a preparation method of a high first-efficiency lithium ion secondary battery negative electrode active material. Lithium-silicon alloy Li prepared by high-energy ball milling 4.4 Si, Li 3.25 Si, Li 1.71 Si has a simple preparation method, no pollution, and high safety. At the same time, adding a suitable solvent as a lubricant in the high-energy ball mill greatly improves the efficiency of the alloying reaction. The lithium-silicon alloy is made into a composite material with pre-milled silicon powder, graphite, and carbon. Its unique structure inhibits the volume expansion of the material during charge and discharge, and the Li x The capacity of Si is high, the conductivity is better than pure silicon, and itself contains lithium, which can inhibit the generation of SEI film in the first week and improve the Coulombic efficiency in the first week of the material. Secondly, the experimental results of the present invention show that the synthesized Li x After delithiation, Si is transformed into amorphous silicon, which effectively alleviates the volume change during charge and discharge, so it exhibits a cycle performance far exceeding that of crystalline silicon. The invention is friendly to the environment, the preparation method and equipment are simple and easy, the safety is high, and it is suitable for industrialized production.

Description

technical field [0001] The invention relates to a preparation method of a high first-efficiency lithium ion secondary battery negative electrode active material. Background technique [0002] As a sustainable energy storage device, lithium-ion secondary batteries have been widely used in smartphones, portable electronic devices, hybrid electric vehicles, and large energy storage devices due to their unique characteristics. However, due to the high irreversible capacity in the first week, low theoretical capacity (372mAh / g), and poor safety during the lithium intercalation process, commercial carbon anode materials have been difficult to meet the requirements of high-energy power sources. [0003] Because of its high specific capacity (4200mAh / g), low voltage platform, and good safety performance, silicon-based anode materials are ideal substitutes for carbon-based anode materials, and have attracted widespread attention. Follow and research. However, the conductivity of el...

AI Technical Summary

Problems solved by technology

[0005] CN107293701A discloses a lithium ion battery negative electrode active material and its preparation method, negative electrode and lithium ion battery containing the negative electrode, but in the preparation process, adding organic solvent and negative electrode active material lithium-silicon alloy to make slurry may cause lithium In the case of silicon alloy and solvent reaction, the active material is lost, the safety is not high, and it is not suitable for industrial large-scale production

[0006] CN108063222A discloses a preparation method of lithium-ion battery negative electrode material and lithium-ion battery. Silicon is deposited on the lithium metal layer by magnetron sputtering, and then the lithium metal layer deposited with silicon is heated and melted to obtain the lithium-ion battery negative electrode material. During the preparation process, lithium-silicon alloy-silicon layer may be obtained, or silicon is oxidized by oxygen in the air during the preparation process to obtain an uncertain mixed coating such as lithium-silicon alloy-silicon dioxide layer. The oxide-containing negative electrode material will inevitably affect the material. Coulombic efficiency in the first week, and the preparation process is complex and requires high equipment, high cost, and poor industrial operability

However, the final product of this invention is a silicon-based material, which does not play the role of pre-lithiation, and does not effectively improve the first effect.

[0008] CN106799497A discloses a production process of nano-lithium-silicon alloy powder. Waste gas will be produced in the process of preparing nano-lithium-silicon alloy by smelting method, which will pollute the environment

Images