What are the "regular vertical stripes" in the 18650 battery lithium ion
2200mahcoating process? How to avoid this pitfall?
In the 18650 battery lithium ion 2200mahcoating process, what we usually
call regular vertical striping (ribbing) defects refers to parallel stripes that
appear along the machine direction, and this defect exists across the entire
coating width.
If you take a comb or a rake and scratch it along the direction of the
machine on a rubber surface that has just come out of the coating head, then
congratulations, you have artificially caught defects with the same appearance.
(As shown below)
The most serious thing about this defect is that once it occurs, your
product yield will suddenly drop to 0%, because you can't find a place where you
can use it, and other things such as protrusions and lines are too big to be
removed when cutting. Block removal is enough.
How regular vertical stripes (Ribbing) are produced:
From a fluid dynamics perspective, the instability of the coating liquid at
different locations causes this defect.
This instability will cause uneven coating thickness with a sinusoidal
waveform distribution in the transverse direction on the coated substrate.
The force difference of the fluid causes uneven distribution of coating
thickness. This force difference is caused by the superposition of
viscoelasticity, inertial force, surface tension and other forces in different
directions of the coating liquid itself.
Generally, this streak is difficult to eliminate through leveling during
the drying process.
Although this difference in coating thickness may be relatively small, this
defect can still be easily observed with the naked eye in many cases or at a
certain angle.
The occurrence of this defect can still be avoided through process
adjustment. From another perspective, it must have a certain process operation
window. Take the slit coating method as an example:
If you use a roller with grooves such as a wire rod to paint, when this
kind of defect occurs, your first feeling is that the groove of the wire rod
causes this defect, but when you change it to a smooth roller, You will find
that this problem will also occur, and then you will be confused.
When you measure the gap width of the stripe and compare it with the groove
width of the wire rod, you find that the two are not the same. Then you'll
realize it's not the groove's fault.
How to effectively avoid this defect:
The first step is to determine whether your current process is within a
reasonable process window. During coating, many process parameters are
adjustable, and through adjustment you can achieve the effect you want.
Second step, if you really don’t know the process window, there are some
common methods.
Dilute your coating solution to reduce the viscosity of the solution
(actually, reduce the Ca of the solution);
See if you can add some surfactant;
If roller coating is used, reducing the diameter of the roller is also an
effective method.
The third step is, if you find a better operating condition, you must make
this operating document into a standard operating procedure, so that you can
make good products sustainably and reproducibly.
Technology Zone Jiangsu Dafeng High-tech Zone has received a lithium 18650
battery lithium ion 2200mahproject with a total investment of approximately 2
billion yuan. It is expected that the 3C certification for electric bicycles
will be officially certified by the end of the year. What are the 18650 battery
lithium ion 2200mahrequirements? What are the "regular vertical stripes" in the
18650 battery lithium ion 2200mahcoating process? How to avoid this pitfall?
Foreign organic flow batteries have made new breakthroughs, which can achieve
enhanced durability, high efficiency and other characteristics. How to
understand the intelligence of power 18650 battery lithium ion 2200mahpACK?
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