Double-hole lithium ion cover plate and rocking-chair type liquid injection device and method thereof

Abstract

The invention discloses a double-hole lithium ion cover plate and a rocking-chair type liquid injection device and method thereof, and belongs to the technical field of lithium ion battery process preparation. The double-hole lithium ion cover plate comprises a first liquid injection hole and a second liquid injection hole which are formed in the two ends of the cover plate respectively, wherein each liquid injection hole is located above an r angle of an A pole core and a B pole core of a lithium ion battery. The cover plate is also provided with welding sites used for being fixedly connectedwith positive and negative lugs. During liquid injection, the double-hole lithium ion cover plate is arranged above the lithium ion battery body and welded and fixed together, and liquid is injectedthrough the liquid injection cups at the left end and the right end, enters the battery in a vacuum state, and can be dispersed in multiple directions and quickly infiltrated after entering a batterycell. The liquid injection time of a single battery is short, and the quick liquid injection requirement is met; and during formation and capacity grading, the internal produced gas can be divided anddischarged through the double liquid injection holes, so that the exhaust area is increased, the bulging of the battery is reduced, and the abnormal phenomenon of liquid overflow is eliminated.

Description

technical field [0001] The invention relates to injecting electrolyte solution into a battery, belongs to the technical field of lithium ion battery technology preparation, and in particular relates to a double-hole lithium ion cover plate and a rocking chair type liquid injection device and method thereof. Background technique [0002] Since the commercial production of lithium-ion batteries in the 1990s, its high specific energy, no pollution, no memory effect, and long cycle life have been widely used in electronic communications, energy storage equipment, electric vehicles, aerospace and other fields. Wide range of applications, with the rapid development of the electric vehicle industry in recent years, the quality requirements for lithium-ion batteries, especially power lithium-ion batteries, are getting higher and higher. insufficient; [0003] 1. Liquid injection background: Electrolyte is an indispensable and important part of lithium-ion batteries. As a medium for...

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Problems solved by technology

[0008] 2.1: The closed formation process is used to charge with a small current, and the battery is vacuumized after the formation is completed. The experiment shows the relationship between the thickness of the closed formation and SOC%. When the SOC is 5%, the thickness changes the most. When the SOC is 25% When the thickness becomes the maximum, so the efficiency of closed formation is low, and it will cause the battery to bulge

[0009] 2.2: In order to prevent bulging and improve efficiency, the opening of the normal pressure is changed to form, but the gas generated will exist in the form of bubbles in the electrolyte, which will overflow outward with the electrolyte, causing corrosion of the battery appearance and deterioration of the workshop environment. At the same time, the opening The formation needs to be carried out in an anhydrous environment, and generally requires a large investment in the construction of a drying room for control, so the formation of the opening will cause the electrolyte to overflow and affect the consistency of battery performance

[0010] 2.3: In order to solve the above problems, many patents currently indicate that the gas is pumped away by means of negative pressure formation, but the gas cannot be completely discharged if the vacuum is too small, and the battery has a risk of swelling. If it is too large, the electrolyte will be pumped away, which will affect the performance of the battery Consistency, so need to improve

[0012] (1) Low efficiency of liquid injection: Since the pole piece of the battery cell and the diaphragm are in a compacted state, the porosity is small, and the electrolyte cannot be quickly dispersed. Therefore, after pressurization, it is necessary to keep the pressure to make the electrolyte gradually settle and then vacuumize. , after vacuuming, it is also necessary to keep the pressure and then pressurize again, resulting in a long injection time;

[0013] (2) The yield rate of liquid injection is low: the pole core occupies 95% of the internal space of the battery after it is inserted into the case. On the liquid, as the electrolyte enters, the internal air is compressed, and a certain pressure difference will be formed inside and outside. If the control is improper and exceeds the bearing range of the shell or cover plate, it will cause the battery to bulge or the explosion-proof valve to burst and leak;

[0014] (3) Low accuracy of liquid injection: the liquid injection pump accurately injects the electrolyte required for a single battery into the liquid injection cup, and then injects it into the battery through the liquid injection cup, and this process can only be controlled by the program at the set The liquid injection is completed within the specified time, and the liquid level of the electrolyte in the liquid injection cup cannot be measured, and there is a certain difference in the liquid absorption speed between the batteries, so there is a phenomenon that the electrolyte cannot be completely filled within the set time, resulting in The battery is low in fluid, and it needs to be refilled after weighing

[0015] (4) High equipment cost: according to the above efficiency requirements, it is known that (34*12 / 8) 51 positive and negative pressure injection levels are required to meet the requirements. At the same time, according to different models, the higher the efficiency requirements, the required injection level The more, so the equipment occupies a larger area, so the equipment manufacturing cost is high

[0016] (5) High formation failure: the size of the liquid injection hole determines the rate of exhaust during negative pressure formation. In order to ensure that the electrolyte is not pumped out, the vacuum degree will be reduced, and too small a vacuum will cause the internal gas to fail. Discharged in time, causing the battery case to swell

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