Method for determining retaining amount and injection amount of electrolyte solution of lithium ion battery

Abstract

The invention relates to a method for determining a retaining amount and an injection amount of an electrolyte solution of a lithium ion battery. The method comprises the following steps of measuring and calculating the porosity AKS of a diaphragm; obtaining the porosities AKC and AKA of a positive electrode plate and a negative electrode plate; according to the length LC, width WC and thickness HC of the positive electrode plate, the length LA, width WA and thickness HA of the negative electrode plate and the length LS, width WS and thickness HS of the diaphragm, calculating the total void volume Vtotal (Vtotal=(AKC X LC X WC X HC)+(AKA X LA X WA X HA)+(AKS X LS X WS X HS)) in combination with the porosities AKS, AKC and AKA of the diaphragm, the positive electrode plate and the negative electrode plate; and calculating the retaining amount mE (mE=rho E X Vtotal) of the electrolyte solution, wherein rho E is the density of the electrolyte solution. In addition, the calculated retaining amount of the electrolyte solution can be multiplied by an injection coefficient to obtain the injection amount. According to the method, the calculation is simple, the injection amount and retaining amount of the electrolyte solution of a designed battery product can be determined in a battery product design stage, and the electrochemical performance reduction and safety risk of the battery caused by excessively large and small amount of electrolyte solutions of the soft package lithium ion battery can be prevented.

Description

technical field [0001] The invention relates to the technical field of soft-packaged lithium-ion batteries, in particular to a method for determining the electrolyte retention and injection volume of soft-packaged lithium-ion batteries. Background technique [0002] Compared with the 1.2V working voltage of Ni-MH batteries, the working voltage of lithium-ion batteries is 3.7-3.8V, which is more than three times that. At present, handheld mobile digital products and some other mobile products that need to be charged basically use lithium ion battery. At present, the main application of lithium-ion batteries can be divided into: aluminum shell lithium-ion batteries, cylindrical lithium-ion batteries and soft-packed lithium-ion batteries; among them, the market of soft-packed lithium-ion batteries has developed rapidly and has been widely used in tablet computers, smart phones and ultrabooks. And other products are widely used. [0003] Among the main materials of lithium-ion...

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Problems solved by technology

[0006] The traditional calculation of the amount of electrolyte injection or retention is mainly based on an empirical value method, that is, the amount of liquid injection and retention is designed according to the capacity of the battery, but if different positive and negative electrodes and diaphragm materials are used, or Different compaction density designs, even batteries with the same capacity have completely different electrolyte absorption capabilities; so this method is not accurate; in addition, the method of weighing after soaking the electrolyte with bare cells can also be used, but this The method requires high environmental humidity, and the operation process is complicated and time-consuming, and the weight of the unabsorbed electrolyte remaining between the pole piece and the diaphragm will also affect the judgment of the final absorbed electrolyte amount, and it cannot be determined at the initial stage of product design. Liquid volume specifications, practical application will be difficult

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