Lithium-containing negative plate and preparation method thereof

Abstract

The invention discloses a lithium-containing negative plate. The lithium-containing negative plate comprises a lithium-containing metal belt, a metal foil and a current collector tab, wherein the size of the metal foil is matched with the size of the lithium-containing metal belt, the lithium-containing metal belt is formed by an upper layer and a lower layer, the metal foil is clamped between the upper layer and lower layer of the lithium-containing metal belt, the lithium-containing metal belt and the metal foil are laminated together by virtue of a laminating device to form a compact combination body, and the metal foil has the characteristic of a rough surface. By adopting a particular structural design and innovative implementation method, the lithium-containing negative plate provided by the invention has the advantages of flat thickness, good current collector effect, good heat dissipation effect, high combination force of the lithium belt and a current collector, and the like, can be used for automatic mass production of batteries, and is very applicable to high-energy density battery systems such as a lithium-sulfur battery, a full-solid lithium ion battery, a different-system primary lithium battery and the like; and the provided plate preparation method is simple, high in operability and suitable for mass production.

Description

technical field [0001] The invention relates to the technical field of lithium battery packs, in particular to a lithium-containing negative electrode sheet and a preparation method thereof. Background technique [0002] Lithium has high electrochemical equivalent and lively performance. Using metal lithium as the negative electrode of the battery can obtain high specific energy, because it is widely used in lithium primary batteries such as lithium manganese dioxide, lithium fluoride, and lithium thionyl chloride, as well as lithium sulfur, all Lithium secondary batteries such as solid-state lithium-ion batteries. During the use of metal lithium sheet as the negative electrode of lithium battery, it is possible that some segments of metal lithium will be consumed, resulting in the reduction or even blockage of the current path, the battery cannot be discharged normally in the later stage, and the discharge capacity is low; in lithium-ion secondary batteries , It may also l...

AI Technical Summary

Problems solved by technology

During the use of metal lithium sheet as the negative electrode of lithium battery, it is possible that some segments of metal lithium will be consumed, resulting in the reduction or even blockage of the current path, the battery cannot be discharged normally in the later stage, and the discharge capacity is low; in lithium-ion secondary batteries , it may also lead to partial recharging, rapid degradation of battery cycle performance, and even the formation of lithium dendrites, resulting in safety issues

In addition, the disadvantages of soft material and poor mechanical strength of lithium metal make the battery preparation process very difficult when lithium metal is used as the negative electrode.

[0003] The conventional solution to these problems is to increase the lithium content and use a large excess of lithium to ensure the continuity of the lithium sheet and the current collection in the later stage of discharge. However, the problem with this approach is that a large amount of excessive metal lithium has safety problems. As the amount increases, the power of fire and explosion also increases. At the same time, excessive lithium sheets also lead to the loss of effective space in the battery, and the volume specific energy of the battery is greatly reduced (the density of metal lithium is 0.534g / cm3, which is much lower than that of conventional lithium batteries. The compacted density of the material, the influence of excess lithium on the thickness and the influence on the weight)

A solution to the poor mechanical strength and soft texture of lithium metal is to make lithium-aluminum or lithium-manganese alloys, which can improve the strength of the metal and improve its processing characteristics, but the improvement effect is limited, especially considering the thickness and mechanical strength. This method is very difficult to apply on automatic production lines (especially automatic winding machines)

Aiming at the problem of metal lithium current collection, a solution given in the patent "Composite Metal Lithium Strip" 200620152212 (Chen Qiang, etc.) is to inlay one or more metal conductive wires that act as current collection channels on the metal lithium strip Or metal strip, the disadvantage of using this method is that the range of current collection guarantee is relatively small, that is, the reliability is relatively low, and the thickness of the general metal strip is about 0.05-0.1mm. Adding a conductive strip to the lithium strip will cause local protrusions , so that the pole piece is uneven, resulting in uneven battery, which cannot be applied in the pursuit of high energy density batteries, and the mechanical strength of the pole piece provided by this method has not been effectively improved, and it is also impossible to realize automatic production

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