As consumers take time to consider the switch from internal combustion engine vehicles to battery electric vehicles (BEVs), manufacturers are ramping up their production strategies for future success. So much so, that over the last year, private industry has committed over $86 billion into the electric vehicle (EV) ecosystem1.
To effectively support the work that is required to bring BEVs to fruition, high-performance robots and their peripherals are being implemented to aid multiple applications. High on the list for car manufacturers to automate are the many tasks associated with EV battery production. From assembly and dispensing to screw driving, laser welding and more, efficient and flexible robots are well-suited for completing many core applications required to facilitate consistent throughput.
That said, robots and sophisticated technologies are being integrated into factories to assist with a variety of applications, especially for EV battery module production. While the following assembly line example does not encompass the entire application scope for all module manufacturing environments, it is a good representation. And, manufacturers working in this space should consider using robotic automation for the following:
FRONT OF LINE TASKS
Skid boxes of individual battery cells are conveyed into the system, where multiple handling robots with pneumatic grippers are typically deployed to depalletize individual cell boxes for downstream processing.
A SCARA-style robot equipped with a cutting tool can be used to quickly and accurately splice the outer wrapper of each depalletized box. During this phase other automated tools can be used along the conveyor to remove the outer cardboard and other packaging that helps to isolate the individual cells.
Cell Scanning and Inspection
Once unpackaged, the boxes of battery cells are conveyed to an automated workstation, where cells are scanned and tested. Each cell’s 2D data matrix is read to compare initial supplier test values vs. their current state. Here, internal resistance and open circuit voltage are measured to ensure each cell is still compliant and has not degraded over time. Upon scanning, each cell is associated with an I.D. that coincides with: 1) the box it’s located in, 2) the cell’s location in the box, and 3) the recorded test values.
MODULE FORMATION TASKS
After cell scanning and inspection, module lines may have several “breakout” stations, where the module container, itself, is populated. These workstations may include:
Pulling multiple battery cells at a time, a robust handling robot with a specialty gripper will then drop the cells into a “mask” that keeps the cells vertical and in the proper orientation.
*Note: battery cells from the scanning workstation that did not pass inspection will remain in the box at this stage. Whether they failed for electrical reasons or for a bad barcode read, unapproved cells are conveyed to a cell reject station. Similarly, when approved battery cells are needed to replace the bad ones, the cell load station keeps a buffer supply that the robot can access.
As mentioned, battery cells that fail to pass the scanning and inspection stage are conveyed to a workstation further down the spur, where the rejected cells are picked by a high-performance robot, then sorted into containers based on their reason for failure. Here, manufacturers can carry out various tasks, such as retesting the battery cells or manually inspecting them before either scrapping the cells or putting them back into production.
Thermal Adhesive Dispensing and Curing
When the cell load station has a full pallet of nesting cells (in the form factor of the module being built), it is then sent to a module cell station. Here, an outer module shell is robotically loaded over the battery cells on the carrier pallet, before a dispensing robot applies thermally conductive adhesive to secure the cells to the shell.
Once the adhesive is applied, the carrier pallet with the cells and shell is robotically transferred into a curing press. Taking approximately an hour, the curing process presses the components into a known form factor to achieve the specified height. After the curing process, the pallet with the cells and shell is robotically removed, before it is transferred to a different pallet to be conveyed to the next process in the manufacturing sequence. In essence, this shell with cells serves as the battery module moving forward.
With the help of an extended reach handling robot, the incoming pallet with the newly formed battery module is “sandwiched” with another pallet at this stage. This allows the module to be flipped and positioned for downstream production. Upon flipping, the battery module remains on the new pallet, while the original pallet returns to the prior station to be reloaded.
Cooling Plate Assembly
The next step in many processes is to cover the bottom of the module with a cooling plate or thermal plate. Critical for regulating the temperature of battery packs and other necessary electronic components, EV battery cooling plates are hollow structures that circulate coolant between two thin aluminum plates.
Before placement, each plate is tested for leaks – as tight, hermetically sealed welds are required to prevent them and maintain safety. Likewise, hi-pot testing is performed to ensure that the insulation is secure and effective.
Approved plates are then attached one-by-one to module bottoms via another automated adhesive process. Each module “married” to a cooling plate is individually loaded by another robot into a curing press. After about an hour, the module is considered structurally sound, and it is removed by the robot and placed on the conveyor (cooling plate side down) to be transferred to the next process.
POST MODULE ASSEMBLY TASKS
Another stage that could vary, depending on a particular modules specifications, are the tasks required after the initial battery module assembly. This may feature a series of automated stations, including:
Here, the module is marked with a serial number, where all of the data for each individual cell is matched to that serial number.
Cell Position Scanning
This workstation helps to accurately identify the position of each cell before the module is moved to the laser ablation process for battery cell cleaning.
Battery Cell Cleaning
As mentioned, a laser ablation process is performed here to clean the top of the battery cells and the busbars, ensuring that the locations where wires will be attached are clean.
Often using an ultrasonic process, wires are attached from the positive and negative surfaces of the cell to a busbar, helping to provide the right current and voltage that is needed for the overall module. Pole testing is also done during this stage.
*Note: depending on application requirements, busbars may be laser welded directly to the cells at this stage.
Using an automated probing method to measure resistance, this process helps to verify good wire bonds. If there are any defects, those wires are removed, and that particular module would return to the wire bonding station for wire replacement. Ultimately, once all tests are good, a high current test is done to ensure that the module is complete and functioning properly.
PACK ASSEMBLY TASKS
Once the module is complete and functioning properly, it is ready to be transferred to a pack assembly location, where applications such as battery tray assembly, including tasks for fire protection cover placement, can occur. A range of handling robots can also be used during this stage to facilitate smooth, efficient production.
Again, while the aforementioned concepts are a well-rounded compilation of EV module assembly tasks, this list is not all inclusive – as every battery module is unique and may entail a different set of applications. For this reason, manufacturers should work with an experienced robot supplier or integrator to determine the best production layout for your facility and requirement needs.
Likewise, to effectively move forward in the BEV space, manufacturers will need to embrace robot usage and the benefits it can bring. From a high level of dexterity and accuracy to fast speed and impeccable repeatability, these virtual workhorses are ideal for high-volume module assembly. Moreover, extremely flexible high-performance robots, coupled with conveyor tracking, enable manufacturers to handle the magnitude of EV automobile production and scale operations as demand grows.
To discover more about EV battery production, listen to our recent webinar, “Robotic Automation for EV Manufacturing,” with special guest host, Jack Uhl, from Eagle Technologies: A Convergix Company.
1 Clean Economy Works - IRA One-Year Review, E2, 2023
Chris Caldwell is a Product Manager