Hidden Complexities of Li-Ion Battery Manufacturing (and How to Solve Them)
March 18, 2025
Written By:
Jacob Walcott | Manufacturing Engineer
Energy storage, much like actual storage, can be costly to build and maintain. As much of the world has pushed itself to become more environmentally friendly, the efficient energy storage problem has been at the forefront of many industries. How can we do this safely? Cost-effectively? Sustainably?
Meeting these challenges requires a deep understanding of process control, material science, and precision manufacturing techniques.
Complexities of Li-ion Battery Manufacturing
A battery cell itself doesn’t appear to be all that complex when it’s broken down. In most cases, you’ll find an anode, cathode, and a form of separator wrapped together creating a pouch of material. This is then attached to the terminals and added to the cell. Finally, the cell is sealed and filled with the appropriate electrolytic solution before being sent off to testing.
It seems simple enough, but battery cell manufacturing can easily see scrap rates rise between 75-100% at a machine level and above 20% plant wide when the process moves out of control! This is well off from Six Sigma’s automotive industry standards of three parts per million (PPM).
Let’s look at the why.
6 Li-Ion Battery Manufacturing Processes That Present Challenges
Targeting improvements around solving the issues presented in the below processes can go a long way in reducing Li-ion battery scrap and improving throughput on the lines.
1. Laser and Ultrasonic Welding
When working with the thin materials often used to create the pack mentioned above, ultrasonic welding can introduce significant risk in the form of tears, cracks, and lack of adhesion—all of which can result in battery degradation through loss of capacitance and voltage measured during formation in the battery management system.
Laser welding used to seal the battery cells must also be precise. Too little energy, misalignment, or excessive power can cause leak failures or long-term failures if the batteries experience water ingress.
Water ingress is a major source of concern for the life cycle of the cells and their ability to charge and recharge.
2. Cleanrooms and Ovens
Cleanrooms and ovens provide one major purpose and that is to remove water content from battery cells and the environments in which they are constructed. Failures of dehumidification systems, vacuum systems, and heating elements can put large number of cells at risk, as they can often hold up to 24 hours’ worth of product within them.
3. Fillers
Fillers introduce the electrolyte to the battery cell once it’s been sealed and dried. There are only two main failure modes here: either too much or too little electrolyte is added. Too little and the battery won’t get to capacity, and too much is a significant cost of resources to the manufacturer and can have potential long-term effects on battery performance.
Controlling the amount is tricky due to the corrosive and hazardous nature of most electrolytes, especially Li-ion. Most often the cause of failure is a component, valve, or otherwise failing on the machine.
4. Formation Systems and Battery Management
The formation system handles the electrical testing and formation of the cells. It’s critical that each cell can be identified and results traceable to it.
This is generally the longest step in the battery cell creation and can take up to two weeks depending on the testing and cell makeup. Ensuring good data management is critical to these systems working appropriately. Broken connectors, faulty controllers, and physical movement impose the largest risks to the smooth operation of these systems.
5. Sorting and Usability
Lastly, cells can—and should—be sorted based on compatibility within a battery pack. Voltage and capacitance differences can affect both performance and charge rate. These can cause battery pack failures and significant time loss in production of the packs.
6. Waste Management
Unlike its counterparts lithium and lead acid batteries, Li-ion batteries lack the recycling streams generally seen in these industries. Hazardous waste is a large cost sink to any business. With future growth expected in energy storage, reclamation of raw materials will continue to grow in importance.
The Key to Process Optimization: Manufacturing Execution Systems
There are many ways to track information in manufacturing, but in the case of batteries, manufacturing execution systems (MES) are the gold standard. The reason for this is simple: it allows you to monitor thousands of parameters and data points.
For example, an MES can track these characteristics (and more) of a battery cell:
- Serial number
- Line it was built on
- Welder it was welded on
- Chamber it was held in
- Time it was produced
- Capacity it can hold
An MES allows for a semi-live view of all cells in the plant and can be used to more easily identify origins of failures and the resulting impact.
What to Consider When Choosing an MES
While these systems are great for traceability and root cause analysis, it’s important to pick one that can manage the data load you intend to use. This can be a major source of downtime, as the system automation is often tied in directly to the MES and will not proceed if the actions in the MES are not executable. It also can cause data to be lost which will often require reprocessing or will end up as waste.
Need Battery Manufacturing Support? Get In Touch
Li-ion battery manufacturing is complex, but it’s not impossible. When data analysis and directed root cause analysis are employed, many of these systems will run themselves (literally!) and are very repeatable. It’s just important to keep both feet on the continuous improvement pedal to keep up with ever-increasing demands.
If you’re stuck on a battery manufacturing issue, please reach out. I, alongside other DISHER experts, have helped clients build complex battery systems and improve manufacturing processes—we’d be happy to help you too.