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A primer on the Lithium Battery Production Process

Sep 10, 2018 11:05:40 PM

Lithium batteries have entered people’s daily life on a large scale, but how much do you know about the technology? Where is it from? What are the steps of the lithium battery production process? This article will show you the detail about the lithium battery production process.


1. The Major Characteristics of Lithium batteries


Advantages:

Lightweight, high energy storage, high power, lower pollution, long life, small self-discharge coefficient and a wide range of temperature adaptation. It is an ideal vehicle power for electric bicycles, motorcycles, cars and large trucks.

Disadvantage:

The price is expensive and there are challenges with safety if improperly handled or housed. However, the development of existing technologies has greatly improved the safety of lithium batteries and reduced the cost.

Comparison of various types of batteries

  Lead acid Nickel-cadmium Nickel hydride Lithium-ion (Traditional Liquid) Lithium-ion (Polymer)

Lead 

acid

 

Mass energy density,

volume energy density, 

operating temperature range,

self-discharge rate,

reliability 

 Mass energy density,

volume energy density,

self-discharge rate

 Mass energy density,

volume energy density,

self-discharge rate,

voltage output

 Mass energy density,

volume energy density,

self-discharge rate,

structural features

Nickel 

cadmium

Better
capacity,

voltage output, price

 

Mass energy density,

volume energy density

Mass energy density,

volume energy density,

self-discharge rate,

voltage output

Mass energy density,

volume energy density,

self-discharge rate,

structural features

Nickel 

hydride

Better capacity,

voltage output, price

Operating temperature range,

better capacity,

self -discharge rate,

reliability

 

Mass energy density,

volume energy density,

operating temperature range,

voltage output,

self-discharge rate

Mass energy density,

volume energy density,

self-discharge rate,

structural features

Lithium-ion

(Traditional

liquid)

Better
capacity,

safety, price

Operating temperature range,

better capacity,

safety,

price

Price,

safety,

self - discharge rate,

voltage output

 

Mass energy density,

volume energy density,

structure characteristics,

safety,

price

Lithium ion

Polymer

Better

capacity

Operating temperature range,

better circulability,

price

volume energy density,

better circulability,

price

Operating temperature range、

better circulability

 

Absolute

advantage

Better

capacity,

price

Operating temperature range,

price

volume energy density

 

Mass-energy density,

volume energy density,

self-discharge rate,

structural features

Mass energy density,

volume energy density,

structure characteristics,

self - discharge rate,

voltage output

 

2. Lithium battery production process


The production process of lithium batteries with different shapes is similar. The following is an example of a cylindrical lithium battery to introduce the production process.

Lithium battery main process fliow chart


3. Lithium battery structure


a. Positive: active material (lithium cobalt oxides), a conductive agent, solvent, adhesive, substrate;
b. Negative:active material(Graphite, MCMB,CMS), conductive agent, solvent, adhesive, substrate;
c. Separation film;
d. Electrolyte;
e. Housing:steel housing, aluminum housing, cover board, current collector, insulate plate, insulate tape.

Cut of a lithium battery


4. The Production Process of Cylindrical Lithium Battery


1. Negative Mixing

The negative electrode is composed of active material (Graphite、MCMB、CMS), a conductive agent, solvent, adhesive and substrate, and these materials are uniformly mixed by the mixing device; the detail process as follows:

lithium battery negative mixing
2, Positive Mixing

The positive electrode is composed of active material(lithium cobalt oxides), a conductive agent, solvent, adhesive and substrate, and these materials are uniformly mixed by a mixing device; the detail process as follows:

lithium battery Positive Mixing
3, Coating

A functional description:The slurry is periodically and uniformly coated on the surface of the transfer collector fluid, drying, and positive and negative electrode rolls are made.
Theory:Coating roller rotation driven slurry, by adjusting the blade clearance to adjust the size as follows, and using a backroll or roller rotation, the slurry will be transferred to the substrate, according to the technological requirements, control the thickness of coating layer to meet the weight requirements, at the same time, by heating to remove solvent in flat out on the base material of slurry, make the solid material to good bonding with the substrate.

lithium battery coating

4. Cold lam

Functional description:Compaction of the poles after coating to achieve appropriate density and thickness.
Theory:The pressure is adjusted by adjusting the gap of the roller, so as to adjust the thickness and density of the electrode being compacted.

lithium battery cold lam
5. Cutting

Functional description:The cold - pressed electrode is rolled up, and cut into large pieces first, and then divided into small pieces of positive and negative electrodes.

lithium battery cutting 

6. Baking

Functional description:The cell needs to be heated in order to seal the cell and prepare the raw cell for further processing. 

lithium battery baking
7. Winding

Functional description:Small positive and negative electrode and isolation film are wound to synthesize the bare electric cell.

lithium battery Winding 

8. Put in housing

Functional description:Since Li-Ion cells are quite toxic and not safe in bare state, they must be housed in an external casing to prevent them from being exposed to the elements. 

lithium battery put in housing
9.  Spot welding

Functional description:This the seal the bottom of the casing once the cells are encased. 

lithium battery stop welding

10. Baking 2

Functional description:This second heating is to complete the melding of the battery with the casing. 

lithium battery baking 2

11. Inject

Functional description:This is the step where the reactive elements are added to form the final state of the cell. 

lithium battery inject

12. Cap weld

Functional description:The top cap of the cell is added at this point so as to completely encase the cell. 

lithium battery cap weld

13. Washing

Functional description:This step removes any residue from previous processes so that the outside of the battery is free from any harmful compounds. 

lithium battery washing

14. Spraying the code

Functional description:Batteries generally get a model number and, sometimes, a serial number. This is where that information is printed on the outside of the cell casing. 

lithium battery spraying the code 

15. Formation

Functional description: The internal positive and negative material is activated by charging and a good SEI film is formed on the negative surface.

Formation: 0.1C CC200min to 3.95V

The assembled battery is given a certain amount of current to excite the positive and negative active substance of the battery. The electrochemical process that makes the battery capable of discharging is called formation. The battery can only be used as a power source after formation.

lithium battery formation

16. External Forming

Functional description:This is where the appearance of the cell is added finally (branding, logos, etc). 

17. Capacity grading

In the manufacturing process, the actual capacity of the battery cannot be completely consistent due to technological reasons. Through certain charging and discharging detection, the process of classifying the battery according to capacity is called Capacity grading.

18. Testing & Package

Functional description:Ready to head out to power your gadgets! 

lithium battery Testing & packing