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Cheap Battery Part 1 - Grade A VS Grade B? What is the Grade B lithium ion battery cells?

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Cheap Battery Part 1 - Grade A VS Grade B? What is the Grade B lithium ion battery cells?

Cheap Battery Part 1 - Grade A VS Grade B? What is the Grade B lithium ion battery cells?


Many clients are confused by the quality standard of lithium-ion battery cells. Some


claimed that they are grade A, grade B. And what is the standard? How the manufactures


define each level? Today, we're going to share with you something about the quality grades.



Quality grades:



Grade A: All parameters (voltage, capacity, internal resistance, self-discharge rate,


dimensions, etc.) within the required ranges. Sometimes, there’s different standard


range to sorting Grade A+ and Grade A- battery cells



Grade B: Some parameters are higher or lower than the standard ranges (high


self-discharge rate, low capacity, high internal resistance, appearance default, etc.)



Grade C: Some manufacturers will define the cells that exceed self-discharging rate


as Grade C


Used cells: Tear down from devices



So what causes the battery cells to be sorted to different levels? There're some factors


that affect the performance of final product during the manufacturing process.



Manufacturing process:


1. Raw material preparing


2. Mixing


3. Coating/Calendering


4. Slitting


5. Winding/Assembling


6. Formation/capacity


7. Aging/sorting




Factor 1 - Raw material



Anode materials and cathode materials are different. The purity of raw materials has great


effect on battery cell’s reliability and performance.

Factor 2 - Mixing



The anode material and cathode material will be mixed separately in tanks. And the


homogeneity of the material mixing also greatly influences the final product.



Factor 3 - Coating/Calendering



After mixing, the material will be coated onto a piece of foil. Anode material pasted onto


an aluminum foil, and cathode materials pasted onto a copper foil. And with the limitation


of coating technology, manufactures cannot distribute the materials evenly.

Factor 4 - Slitting



As the mixed materials are coated onto the foil of a width up to one meter. So precision


cutting has a deep impact to ensure the correct self-discharge of battery cells. After


cutting, both edges of the foil will leave some notches, which have the risk of piercing


the separator between anode and cathode pad. Then resulted in internal


short-circuit and higher self-discharge. This is also a very important reason that


causes battery explosion.



Factor 5 - Winding/Assembling



In this process, it’s not easy to inject exactly the same volume of electrolyte inside the


battery cell. So it’s also a factor that will affect the perseverance of final product.




For all the factors mentioned above, there are no two battery cells being exactly the same


for all the parameters, so manufacturers or clients will define a standard parameter range


of a batch of battery cells. And different batches of product have different standards.


After activating the finished battery cells with formation process. Manufactures


sort the cells within the standard parameters range into grade A battery cell group. And


for the ones that are out of provided range, factories will sort them into unqualified


battery cell groups. Those battery cells cannot meet the standard of car level


homogenizes. However, some clients find it works for single cell or small series/parallel


utilized after resorting. That is grade B/C battery cells. Which is much cheaper than


grade A cells.



Note: Anyway, since the evacuate factors including battery dimensions, weight,


stock time, voltage, capacity, internal resistance, self-discharge rate, etc.,


there’s a risk to use grade B battery cells even after resorting.



We have made a video to explain more details of grade B cells if you’re interested.


And next time we’ll share some tips about how to distinguish Grade A and Grade B cells.



Pub Time : 2019-11-21 16:32:12 >> News list
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