High-strength ultra-thin composite lithium foil, manufacturing method thereof, and lithium-ion secondary battery

Abstract

The invention relates to the technical field of lithium batteries and particularly discloses a high-strength ultrafine composite lithium foil and a manufacturing method thereof as well as a lithium ion secondary battery. Lithium metal and fibers are heated, mixed, rolled and molded, and the thickness of the composite lithium foil is 2-100 microns. Fiber materials in the composite lithium foil account for 2%-50% in weight percent. The fibers are one or more of nano carbon fiber tubes, vapor deposition carbon fibers, ultrafine carbon fibers and ultrafine graphite fibers. The fiber materials are doped into the lithium foil so that on the one hand, the strength effect of a framework enhanced foil is realized, the strength of the lithium foil is improved, the production of the thin lithium foil is possible, and a bottleneck key technology difficulty in machining of the ultrafine lithium foil is overcome; on the other hand, the doped fiber materials can prevent adhesion between the lithium metals so that the problem that the lithium foil is easily adhered together in machining and using processes is solved and the application range of the lithium foil is enlarged; and the produced composite lithium foil can be made into a coiled material so that the requirement for large-scale production of the battery is met.

Description

technical field [0001] The invention relates to the technology in the field of lithium batteries, in particular to a high-strength ultra-thin composite lithium foil, a manufacturing method thereof, and a lithium-ion secondary battery. Background technique [0002] When a lithium-ion battery is first charged and formed, it will sacrifice part of the lithium ions in the positive electrode material to form a layer of "solid electrolyte interface film" (solid electrolyte interface), referred to as SEI film, on the negative electrode material. Different anode materials consume different amounts of lithium ions to form this layer of film. At present, graphite-based anode materials commonly used consume about 10%, while silicon-based and silicon oxide-based composite materials consume more lithium ions, even up to 40%. [0003] At present, the negative electrode lithium replenishment method is used to solve the problem of lithium ion consumption. Lithium replenishment can be carrie...

AI Technical Summary

Problems solved by technology

Due to the fine particles and high surface activity of lithium powder, it is very easy to cause safety accidents such as explosion, so the processing and manufacturing of lithium powder is limited

Lithium foil is much safer than lithium powder, but lithium metal is very soft, the Mohs hardness of lithium is only 0.6, and lithium metal itself is very easy to stick, it is very difficult to process it into a few micron foil according to the traditional method. Generally, the thickness of the lithium foil used for lithium supplementation in lithium-ion batteries is required to be 2 to 100 microns. Pure lithium is soft and easy to stick, so it is impossible to make such a thin lithium foil.

If a relatively thick lithium foil is used to replenish lithium, the lithium metal cannot be completely consumed during the formation of the battery, and the excess metal lithium in the battery will reduce the safety of the battery