Process Explanation-NMP is one of the raw materials for lithium batteries.

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ZESHENG shows you the use of NMP(1-Methyl-2-pyrrolidinone) solvents in lithium batteries:

The dosing process(lithium battery) is actually mixing the various components of the slurry together in standard proportions and modulating them into a slurry to facilitate uniform coating and ensure the consistency of the pole piece.

The dosing consists of five processes, namely: pretreatment of raw materials, blending, wetting, dispersion and flocculation.

Principle of anode dosing:

1、Physical and chemical properties of raw materials.

Lithium cobaltate: non-polar material, irregular shape, particle size D50 is generally 6-8 μm, water content ≤0.2%, usually alkaline, PH value is about 10-11.

Lithium manganate: non-polar substance, irregular shape, particle size D50 is generally 5-7 μm, water content ≤0.2%, usually weakly alkaline, PH value of about 8.

Conductive agent: non-polar substances, grape chain-like, water content 3-6%, oil absorption value ~300, particle size generally 2-5 μm; mainly ordinary carbon black, superconducting carbon black, graphite milk, etc., in the bulk application of the general choice of superconducting carbon black and graphite milk compound; usually neutral.

PVDF adhesive: non-polar substance, chain-like, molecular weight ranging from 300,000 to 3,000,000; molecular weight decreases after water absorption, and viscosity becomes poor.

NMP solvents(N-Methyl-2-pyrrolidone): weakly polar liquid, used to dissolve/swell PVDF, and also used to dilute the slurry.

2、Pre-treatment of raw materials

Lithium cobaltate: dehydration. Generally use 120 oC atmospheric pressure baking for about 2 hours.

Conductive agent: dehydration. Generally baked at 200 oC for 2 hours at normal pressure.

Binder: Dehydration. Generally baked at 120-140 oC for about 2 hours at atmospheric pressure, depending on the molecular weight.

NMP solvents(1-Methyl-2-pyrrolidinone): Dehydration. The use of dry molecular sieve dehydration or the use of special pick-up facilities, direct use.

3、Mixing of raw materials.

(1) Dissolution of binder (according to standard concentration) and heat treatment.

(2) Lithium cobaltate and conductive agent ball milling: so that the initial mixing of powder, lithium cobaltate and conductive agent bonded together to improve the agglomeration effect and the conductivity.

After mixing into a slurry will not be distributed in the binder alone, ball milling time is generally about 2 hours; to avoid mixing impurities, usually use agate balls as ball milling meson.

Dosing precautions:

1、Prevent mixing with other impurities.

2、Prevent the slurry from splashing.

3、The concentration of the slurry (solid content) should be adjusted gradually from high to low, so as not to increase the trouble.

4, in the interval of stirring process should pay attention to scrape the edge and scrape the bottom to ensure uniform dispersion.

5、The slurry should not be set aside for a long time to avoid precipitation or uniformity reduction.

6、The materials to be baked must be sealed and cooled before being added to avoid changes in the nature of the component materials.

7、The length of stirring time is based on the performance of the equipment and the amount of material added; the use of the stirring paddle is replaced by the difficulty of slurry dispersion, and the speed can be adjusted from slow to fast if it cannot be replaced, so as not to damage the equipment.

8、Sieve the slurry before discharging to remove large particles to prevent breakage during coating.

9, the batching staff to strengthen training to ensure that they master the expertise, so as not to cause a big disaster.

10, the key to batching is to disperse evenly, master the center, other ways can be adjusted by themselves.

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4.Will chemical injuries occur to people who work in NMP(1-Methyl-2-pyrrolidinone) or battery factory for a long time?

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