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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.

Conclusion:

 

 

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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