Marking technology in battery manufacturing

Manufacturing plants are moving to digitalization and high automation direction.

One of the most important topic regarding industry 4.0 is DATA. When we talk about data we need to consider multiple subtopics like data collection, data management and data analysis.

High tech lithium battery manufacturing plant are able to collect product, process and equipment data continuously. Data collection then can trigger data analysis and all activities in direction of continuous improvement trying to optimize production and quality performance.

The lithium battery manfuacturing business is trying to do more, introducing the battery passport.

The battery passport will collect all strategic and production information of our battery cells and pack trying to garantee reliable value chain and high quality product for the end users.

All these topics pass through a series of activities and engineering technology which involved several companies and type of industry: from software to sensor industry, passing through the marking technology industry.

We would like to spend few words about the marking technology applied in lithium battery manufacturing.

The product marking in lithium battery manufacturing could involved multiple battery components:

• Electrode reel and separators: usually the traceability pass through a QR /DMC /Barcode on core reel;
• Cell:
  • immediately after the cell creation (winding, stacking etc) the battery cell can be marked to keep the traceability. Especially in production environments which don’t foreseen automatic material handling like conveyors. Here the marking process is usually done on closing tape material, trying to avoid to touch or damage electrodes and separator layers.
  • after the cell insertion in the case (pouch or metal) the product must still traceable, so it’s important the marked Code still visible. In this case the marking process can take place on pouch film, current lead (for pouch battery) or case or lid (for prismatic and cylindrical cell.

So the lithium battery marking, could involved different material so trigger different quality requirements.

In case of laser marking on closing tape we need to ensure to don’t damage the marking tape and don’t damage the substrate as for example the separator.

If we are moving to inkjet printing technology we need to esnure the ink will not contaminate the electroylte once the E-Filling process take place.

For metal case and Lid, the main concern is about corrosion: the marking technology should resist during the working life of the product but even don’t trigger any corrosion issue which can affect negatevily the battery performance. So our marking technology should be gentle enough to don’t damage the nickel plate coating on cases and lids. Another way is print a code on the label and then apply the label on lid/case surface.

For sure:

• Laser marking
• Inkjet printing
• Labeling

technologies foreseen different CAPEX, OPEX, process unit dimension, cycle time and integration effort so trigger different applications.

Let’s start with Inkjet printing technology:

• The first thing to consider is verify the ink doesn’t dissolve in the electrolyte and trigger any contamination issue
• The unit prices move from 15’000€ to 25’000€ so lower than Laser marking technology but foreseen scheduled downtime
• Long production stops can cause mulfunctions at the unit if not cleaned in advance
• The marking cycle is quite low, we are talking about some hundreds milliseconds
• The controller unit and ink tank are remotized, the printing head is the one installed directly on conveyor/equipment

Laser marking technology:

• CAPEX and OPEX depends mainly on laser type. Currently in lithium battery manufacturing the most used laser technology is the UV laser which foreseen a gentle interaction with materials so respect in most of the case the quality requirements. UV lasers usually from 2 to 5W are the most expensive technology with and average price of 40’000€ which in some case can reach up to 65’000€ per unit. Emerging technologies like Green lasers and Blu lasers are showing very good results in term of quality and cycle time. Blu laser marking units are able to go down with cycle time maintaning a good readability of the code with CAPEX several hundred thousands euro lower than UV (average price 15’000 – 25’000€ per unit); the green lasers required higher cycle time and foreseen higher cost compare to blu lasers but still cheaper than UV. We need to consider Blu and Green laser marking technology garantee longer working life so lower OPEX compared to UV technology.
• Indicated to mark on metals, plastic film and coated material whithout damaging them
• No maintenance required, or at least minimumn maintenance effort compared to Inkjet printing technology
• In some case the laser source could be integrated in laser marking head, in some case is remotized.

In order to find the best marking technology based on marking quality results, test campaign is needed to find the right process parameters.

A feasibility study can just provide a rough indication about the laser technology and marking device limit in term of power and cycle time. Remember the marking process should satisfy the product quality requirement but even the reading qualtiy requirement by reading sensors: if your code is not readable, your product traceability system becomes useless.

Here below you can find some picture comparing UV, Blu and Green Lasers on battery application:

Please, consider the pictures above are not obtained after a process development campaign but are results of quick feasibiltiy study.

Labeling technology

• This system foreseen a marking technology and a labeling group. So the cost of the overall system is higher than single inkjet printing unit.
• The cycle time is similar to the single inkjet technology application
• Could be use and applied for cell marking after the insertion in the case (metal or pouch)
• Schedule downtime and maintenance is requried to load the label reel and make maintenance at the inkjet unit
• The unit dimension is for sure bigger than the other options.

So, to summarize we can say for lithium battery manufacturing, many technologies are available with different features, performance and Cost.

Each project and product has different needs and only with a deep analysis and dedicated test trials is able to evaluate the best solution.

If you want to know more or get support in establish your traceabiltiy system and define the best marking technology contact us:

info@bonsaitechnology