How to Safely Shred Fully Charged Lithium-Ion Batteries

Are you wondering if you can safely shred charged lithium-ion battery cells? Do you have questions about how it can be done on an industrial scale?

If so, you are in the right place. In this article, you will learn all about shredding charged cells and, by the end, you will be able to decide if a dry or wet shredding operation is right for you. If you are interested in learning more, stay tuned for upcoming articles where we will cover every detail.

The Importance of Discharging Batteries Before Shredding

Before shredding lithium-ion batteries, it is best practice to ensure they are not fully charged. Ideally, batteries should be discharged to 30% or less, with 20% being the safest threshold. Fully charged cells pose a significant safety risk, which is why various safety measures are put in place to prevent accidents that could impact people, the environment, and the equipment.

Shredding Methods: Dry vs Wet Processing

There are two primary methods for shredding lithium-ion batteries: dry processing and wet processing. Let’s look at each approach in detail:

Dry Processing

1. Airlock System: The dry shredding process begins with a conveyor feeding batteries into an airlock system. A double airlock mechanism is preferred for enhanced safety. The airlock consists of two gates:
   • The first gate opens to allow the material to fall into a chamber.
   • Once inside, the first gate closes, and the second gate opens, allowing the material to move into the shredder.
2. Shredding in an Inert Chamber: The shredder operates in an inert gas environment to minimize oxygen levels. Despite this, some small explosions or fires can still occur since lithium-ion batteries generate their own oxygen. However, monitoring and controlling the conditions inside the chamber help mitigate risks.
3. Proceeding to the Next Step: After shredding, the material moves downstream for further processing, which we will cover in the next part of this series.

Wet Processing

For increased safety, especially when dealing with a higher likelihood of fully charged battery cells, wet shredding is a great approach.

1. Similar Airlock System: Like the dry process, wet shredding starts with a conveyor and dual airlock system before reaching the shredder.
2. Dual or Quad Shaft Shredder: A dual or quad-shaft shredder equipped with hooks is used for the shredding process. The chamber is flooded with water, which serves multiple functions:
   • It suppresses sparks and flames immediately upon shredding.
   • The water level is maintained just high enough for the hooks to grab the batteries effectively and pull them down into the shredder.
3. Post-Shredding Water Removal: The shredded material then moves into screw augers and further downstream processing which will remove as much water as possible before the next stage of recycling.

Minimizing Risks and Optimizing the Process

To ensure maximum safety and efficiency:

• Always limit the number of fully charged batteries entering the system.
• Consider pre-processing methods that completely discharge batteries before shredding.
• Regardless of the method used, always monitor heat, oxygen levels, and potential thermal events to maintain a controlled environment.

Conclusion

In some instances where processors intend on not discharging the batteries, a wet, fully submerged system is mandatory. We hope this guide has been helpful on how to shred fully charged or semi-charged lithium-ion batteries. If you have any questions, please be sure to contact us through the Let’s Chat button below and we will be in touch soon.