Lithium-ion battery and its lithium-rich anode sheet

Abstract

The invention provides a lithium ion battery and a lithium-rich anode sheet. The lithium-rich anode sheet comprises: a current collector; and a diaphragm, which contains an active substance and is formed on the current collector, wherein the diaphragm and the current collector form an initial anode sheet. The current collector in the initial anode sheet is a porous current collector. The initial anode sheet is rich in lithium on one side, and the lithium rich amount matches the lithium supplement capacity needed by the initial anode sheet. The lithium ion battery includes: a cathode sheet; an anode sheet; an isolation membrane disposed between the cathode sheet and the anode sheet; and an electrolyte solution. The anode sheet is a lithium-rich anode sheet. The lithium-rich anode sheet of the lithium ion battery provided by the invention not only overcomes the excess lithium supplement problem in traditional lithium-rich anode sheets, and also can effectively control the lithium supplement amount of the anode so as to realize uniform lithium supplement and enhance the first coulombic efficiency of the lithium ion battery adopting the lithium-rich anode sheet. Thus, the energy density of the lithium ion battery is greatly improved, and the lithium ion battery can be ensured with better electrochemical properties.

Description

technical field [0001] The invention relates to a lithium ion battery, in particular to a lithium ion battery, a lithium-rich anode sheet and a preparation method thereof. Background technique [0002] In 1991, Sony Corporation of Japan creatively adopted carbon materials as the anode active 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. However, with the miniaturization, long-term standby and multi-functional development of portable electronic devices, these devices have higher and higher requirements on the energy density and charge-disc...

AI Technical Summary

Problems solved by technology

When using this method to replenish lithium, since the existing process cannot produce thinner lithium metal sheets, the amount of lithium that the anode sheet can absorb is far less than the amount of lithium provided by the metal lithium sheet, resulting in excessive lithium replenishment and battery failure. Lithium analysis, poor cycle performance and other issues

In response to this problem, the applicant’s Chinese Patent Application Publication No. CN103199217A announced on July 10, 2013 proposes that the perforated metal lithium sheet is used to cover the surface of the anode sheet, and then wound to form a battery, and then The method of perfusing the electrolyte to prepare lithium-rich lithium-ion batteries effectively solves the problem of not being able to produce thin enough metal lithium sheets

However, when the amount of lithium supplementation required for the battery cell is low, it is required that the lithium sheet used is thin enough, or the area of ​​the holes in the perforated lithium sheet is large enough, whether the lithium sheet is thinner or the hole density is increased (punched) When the pore density is too large, the lithium sheet is easily broken, which is not convenient for production), which will cause the production cost of the battery to rise sharply

[0004] Although the above lithium supplementation methods can realize lithium supplementation and prepare lithium-rich diaphragms, they all need to supplement lithium on both sides of the electrode. In the actual production process, two processes are usually required: first, lithium enrichment on one side, and then cold pressing to make The lithium sheet rich on the surface of the electrode is attached to the diaphragm; the process is then repeated on the other side of the electrode, resulting in complex production processes, low production efficiency, large dry room footprint, and high operating costs

In addition, during the cold pressing process, the too thin lithium foil will be closely attached to the electrode, so that the electrolyte cannot pass through the covered area, resulting in poor wetting, which will cause black spots on the surface of the anode diaphragm when the battery is fully charged, which will affect the quality of the battery. capacity play

[0005] From the perspective of production process, due to the limitation of coating technology, it is difficult to achieve the same thickness of the coating layer coated on the current collector. Ground: The total capacity of the anode active material per unit area is 1.1 times the total capacity of the cathode active material per unit area; due to the additional coating weight of the anode, the energy density of the battery cell is reduced

Images