Preparation method of stable slurry of lithium ion battery

Abstract

The invention discloses a preparation method of stable slurry of a lithium ion battery. The preparation method comprises the steps of: preparing mixed material and glue from an active substance, a conductive agent, a bonding agent, a dispersing agent, a solvent and other additives by a few steps of dry mixing, wet mixing and glue preparation, and then subjecting the mixed material and the glue to wet mixing by a stirrer to obtain mixed slurry, and further comprises the steps of: (1) dispersing the mixed slurry for 10 to 20 minutes by a high speed dispersing machine of 15 to 50m / s, and storing the slurry in a storage tank upon the completion of the dispersion; (2) returning the slurry in the storage tank to the stirrer and then dispersing the slurry for 10 to 20 minutes by the high speed dispersing machine according to the step (1); (3) circularly repeating the step (1) and the step (2) 2 to 5 times; and (4) after the dispersion is completed, performing defoaming, filtration and iron impurity removal on the slurry based on the prior art to obtain the finished product. The slurry in the invention is homogeneous in dispersion and can be stable for a long time; and compared with the traditional way that the stirrer is used to stir for a quite long time, the method can shorten the time for slurry preparation greatly and is favorable for automatic continuous production.

Description

technical field [0001] The invention relates to a preparation method of lithium ion battery slurry. Background technique [0002] In the process of making lithium-ion batteries, the slurry preparation is a very important link. The conventional compounding method in the prior art is to dry mix active materials, conductive agents, binders, dispersants, solvents and other additives. , glue making and wet mixing several steps, and then use a mixer to stir for a long time to make a mixed slurry. The disadvantages are (1) the stirring speed of the mixer does not exceed 50 rpm, because the speed is too slow to reach Dispersion effect, the slurry is prone to abnormal phenomena such as delamination and sedimentation during coating, resulting in uneven coating surface density or even failure to coat. (2) Uneven dispersion of the conductive agent will increase the internal resistance of the battery ; (3) It takes a long time to stir, which affects production efficiency. At present, t...

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Problems solved by technology

[0002] In the process of making lithium-ion batteries, the slurry preparation is a very important link. The conventional compounding method in the prior art is to dry mix active materials, conductive agents, binders, dispersants, solvents and other additives. , glue making and wet mixing several steps, and then use a mixer to stir for a long time to make a mixed slurry. The disadvantages are (1) the stirring speed of the mixer does not exceed 50 rpm, because the speed is too slow to reach Dispersion effect, the slurry is prone to abnormal phenomena such as delamination and sedimentation during coating, resulting in uneven coating surface density or even failure to coat. (2) Uneven dispersion of the conductive agent will increase the internal resistance of the battery ; (3) It takes a long time to stir, which affects production efficiency

At present, the materials for lithium-ion batteries are evenly dispersed in a solvent to form an excellent slurry, and the method of adding a dispersant is used; however, it still has limitations. For nano-materials such as conductive agents, especially lithium iron phosphate The nano-active substances are not very effective; and in order to disperse the difficult-to-disperse nano-materials, people usually add more dispersants, but the dispersants are harmful to the performance of the battery. The greater the impact, the most obvious is that the capacity of the battery decreases rapidly with the increase of the dispersant

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