Coating for lithium-battery diaphragm, diaphragm and preparation method for diaphragm

Abstract

The invention discloses a coating for a lithium-battery diaphragm, the diaphragm and a preparation method for the diaphragm. The coating for the lithium-battery diaphragm comprises powder of a lithium titanate compound and an adhesive, wherein the lithium titanate compound is one or more selected from a group consisting of Li<4+x>Ti<5>O<12> and Li<1+x>Ti<2>(PO<4>)<3>, wherein x is no less than 0 and no more than 3. The coating for the lithium-battery diaphragm can improve the puncture strength of the diaphragm and supplement lithium to an electrical core, and the preparation method is simple in process and easy to operate. Compared with conventional coatings, Li<4+x>Ti<5>O<12> provided by the invention is a substance with certain electron conductivity and high ion conductivity, so the ion conductivity of an electrolyte can be improved and the electrical properties of the electrical core are enhanced; under the condition of over-charging, Li<4+x>Ti<5>O<12> can store a part of Li ions, effectively prevent precipitation of surplus lithium and improve the over-charging performance of the electrical core; and compared with conventional lithium supplementing technology, the coating is easier to operate and enables security to be substantially improved.

Description

technical field [0001] The invention relates to the technical field of lithium batteries, in particular to a lithium battery diaphragm coating, a diaphragm and a preparation method for the diaphragm. Background technique [0002] Existing lithium batteries are mainly composed of positive electrode materials, negative electrode materials, separators and electrolytes. The diaphragm is one of the core key materials of lithium batteries. In lithium-ion batteries, the separator mainly plays the role of preventing positive and negative electrodes from contacting and allowing ion conduction. [0003] At present, the existing commercial lithium-ion batteries mainly adopt polyolefin diaphragm materials with microporous structure, such as single-layer or multi-layer films of polyethylene (PE) and polypropylene (PP). The polyolefin separator exhibits large thermal shrinkage under high temperature conditions. Due to the heat accumulation inside the battery, the polyolefin separator is...

AI Technical Summary

Problems solved by technology

Although this method can also play the role of lithium supplementation, the amount of lithium that the negative electrode sheet can absorb is far less than the lithium provided by the metal lithium sheet, so it will cause uneven lithium intercalation and lead to deformation of the electrode sheet, and subsequent cycles Lithium is also prone to occur in

[0007] In addition, the Japanese patent application with the application number JP2005038720 mentions that a metal lithium layer is evaporated on the surface of the negative electrode sheet by vacuum evaporation. Although the thickness of the evaporated lithium layer is thinner than that of the metal lithium sheet, the metal lithium layer The thickness of the lithium layer is difficult to control, and the whole process must be in a vacuum environment, the evaporation efficiency is also low, and the transfer treatment of the subsequent pole piece is also more complicated and the cost is higher

[0008] For simultaneously improving the puncture strength of the diaphragm and replenishing lithium, there is currently no feasible solution

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