Lithium-rich pole piece of lithium ion battery and preparation method thereof

Abstract

The invention provides a lithium-rich pole piece of a lithium ion battery and a preparation method thereof. The lithium-rich pole piece comprises a current collector, a diaphragm and a porous lithium piece, wherein the diaphragm contains an active material and is formed on the current collector; the diaphragm and the current collector form an initial pole piece; and the porous lithium piece covers the diaphragm, and the capacity of the porous lithium piece is matched with the capacity of lithium added to the anode. The preparation method comprises the following steps of: preparing a slurry from the active material, a conductive agent, an adhesive and a solvent, and then applying the slurry on the current collector and drying to obtain the initial pole piece, so that the slurry applied on the current collector becomes the diaphragm after being dried; punching a metal lithium piece to obtain the porous lithium piece, so that the capacity of the porous lithium piece is matched with the capacity of lithium added to the anode; and covering the diaphragm surface of the initial pole piece with the porous lithium piece, to obtain the lithium-rich pole piece of the lithium ion battery. According to the invention, the lithium amount added to the anode can be precisely controlled, the lithium adding uniformity is increased, the first coulombic efficiency, the energy density and the electrochemical properties of the battery are increased, battery deformation is alleviated, the process is simple, and the cost is low.

Description

technical field [0001] The invention relates to a lithium ion battery, in particular to a lithium-rich pole piece of the lithium ion battery and a preparation method thereof. Background technique [0002] In 1991, Sony Corporation of Japan creatively adopted carbon materials as the anode material of lithium-ion batteries, which brought revolutionary changes to the field of lithium-ion batteries. Due to the many advantages of lithium-ion batteries, such as high voltage, small size, light weight, high specific capacity, no memory effect, no pollution, small self-discharge and long cycle life, etc., its application in the field of mobile devices has been unprecedented. development, including mobile phones, video cameras, notebook computers, and other portable appliances. Since entering the 21st century, human beings' awareness of environmental protection has been further enhanced, making lithium-ion batteries have greater application potential, and are generally considered to ...

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Problems solved by technology

[0004] In order to obtain a lithium-rich pole piece that improves the first Coulombic efficiency of the cell, domestic and foreign experts have carried out extensive research and achieved some results. Among them, the Chinese patent with the publication number CN1830110A mentioned that lithium metal, anode material and non-aqueous liquid mixing to form a slurry, coating the slurry on the current collector, and then drying the slurry to prepare a lithium-rich pole piece of a lithium ion battery in which lithium metal particles are incorporated into the coating layer; in the coating layer of the pole piece, due to the metal lithium Existence, so that the density of the active material in the pole piece is reduced, and the connection between the active material particles is reduced, and the electronic resistance is increased; at the same time, although this method can play the role of lithium supplementation, and finally achieve the purpose of improving the first Coulombic efficiency of the battery cell, but the whole The production process of the battery cell must be completed in a dry room, and it is difficult to blend metal lithium and anode materials, so the production cost is high

Chinese Patent Application Publication No. CN1177417A adopts the method of covering lithium metal sheet on the surface of the anode sheet, then winding it into a battery, and then pouring electrolyte into the lithium-rich lithium-ion battery; when using this method to supplement lithium, due to the existing Some processes cannot produce thinner lithium metal sheets, so the amount of lithium that the anode sheet can absorb is far less than the amount of lithium provided by the metal lithium sheet, which leads to problems such as excessive lithium supplementation, lithium precipitation in the battery cell, and poor cycle performance.

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