Lithium strip and preparation method and application thereof

Abstract

The invention provides a lithium strip and a preparation method and application thereof. The lithium strip comprises a polymer of a networked structure and lithium metal particles bonded to the surface of the polymer, has higher mechanical strength than a common lithium strip, is high in fitting degree with an electrode pole piece and high in lithium supplementing efficiency, and can effectively improve the first effect of a battery. The preparation method comprises the following steps: premixing a fibrosis polymer with lithium metal particles, drawing the fibrosis polymer to form fibers underthe effect of shearing force, and carrying out cold pressing treatment or hot pressing treatment under the protection of inert gas until the thickness of the fibers reaches a preset thickness, so asto obtain the lithium strip. According to the invention, influence on lithium metal particles is small. The generation of lithium by-products is reduced, no solvent is needed in the preparation process, the tedious processes of solvent screening and solvent recovery are reduced, and the cost and environmental pollution are reduced.

Description

technical field [0001] The invention belongs to the field of battery materials, and relates to a lithium strip, a preparation method and application thereof. Background technique [0002] With the rapid development of new energy vehicles, the requirements for energy density and safety performance of vehicle power batteries are constantly increasing. It is estimated that by 2025, the energy density of power batteries will reach more than 500Wh / kg. With the continuous improvement of the energy density of power batteries, the gram capacity and compaction density of existing negative electrode materials have reached the limit value. Therefore, the use of silicon carbon materials will be a hot spot in the future. At the same time, the low initial charge and discharge efficiency of silicon carbon materials, large expansion, and long-term cycle will bring about material pulverization problems, as well as matching problems with related electrolytes and glues, which have always plag...

AI Technical Summary

Problems solved by technology

[0004] Among the current lithium supplementation technologies that can be industrialized, lithium powder and ultra-thin lithium strips are the main research trends. However, the preparation process of lithium powder is relatively complicated, involving the heating and melting of lithium metal and post-processing. The use of ultra-thin lithium strips has strict requirements on equipment and environment, which also limits the large-scale use of lithium powder. Most of them can be completed at a lower temperature, so the difficulty of manufacturing is much lower than the preparation process of lithium powder

[0005] However, most current lithium ribbons use metal films or polymer films that are inert to metals as supports. This is because lithium metal is weak and very soft. When the thickness of lithium metal drops to a certain level, it is difficult to maintain The complete continuous phase is easy to break; this increases the difficulty of using the lithium ribbon in the later stage. During use, the lithium ribbon must be peeled off from the support before further use, which will also cause waste of lithium ribbon and increase costs; In addition, most of the lithium strips currently on the market are tens to hundreds of microns. These lithium strips are directly used in most battery systems, and the amount of lithium supplementation is excessive, which will inevitably cause extreme damage during the early cycle of the battery. Lithium sheet analysis, causing battery short circuit

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