Battery technology has evolved to where you can drive an electric vehicle (EV) almost 500 miles on a charge while charging networks continue to grow across the United States. Electric cars out-accelerate their gasoline-powered cousins and include technology features only dreamed of 10 years ago. EVs are not simply different, they represent a new species of transportation.
Technology and acceptance are reaching a critical tipping point that is spurring a surge in electric cars across the world. Long-established original equipment manufacturers have embraced this technology and committed to changing their entire fleet over to battery-powered vehicles.
All of this means we have to build a lot of batteries, and there is a surge of battery plants now being planned in the US. In many ways, these manufacturing plants are like other large-scale manufacturing facilities. However, large-scale battery manufacturing plants have unique design and construction considerations that can be boiled down into four key challenges.
Challenge No. 1: Creating and Maintaining an Ultra-Low Humidity Environment
While high-level clean rooms are adequate for semiconductor manufacturing, they contain 30 times more humidity than the ultra-low relative humidity (RH) requirements for lithium-ion battery manufacturing. Uncontrolled humidity in battery plants will cause defects resulting in reduced product life, performance, overheating during charging, and potentially thermal runaway—i.e., fires.
Lithium-ion battery manufacturing demands the most stringent humidity control and the first challenge is to create and maintain these ultra-low RH environments in battery manufacturing plants. Ultra-low in this case means less than 1 percent RH, which is difficult to maintain because, when you get to <1 percent RH, some odd things start to happen.
When designing a clean room, one tool to keep the room clean is to pressurize the volume, which pushes out the air so that particulate matter can’t infiltrate the space. However, that approach alone will not maintain a <1 percent RH dry room. At ultra-low humidity, moisture migrates in the opposite direction of the air stream. To address moisture issues, a dry room must be moisture tight, i.e., sealed all the way around in a complete envelope—underneath, on all sides, and at the top.
Once the seal is complete, one of the next largest sources of moisture is people. Every breath releases moisture into the atmosphere, and at <1 percent RH, water is drawn from your skin creating humidity “puddles” in a dry room environment. To successfully identify and mitigate humidity puddles, advanced design tools need to be employed. For example, computational fluid dynamic (CFD) modeling is used to understand airflow within a space and identify where humidity puddles are likely to occur. Then, your design team can take action by adjusting the air streams or adding additional equipment.
Choosing the Right Materials
In addition to using insulated metal panels with butyl seals and cam locks, airlocks at entry points, and sealed vapor barriers under floor slabs, it is also important to note that ultra-low humidity rooms can dry out traditional lubricants and sealants. So much so that if you install a door-closer that’s not designed for this type of space, the sealants can turn to powder over time. That’s why it’s vital to consider the effect of ultra-low humidity on all materials as they can potentially be impacted by this type of environment and compromise the room.
Challenge No. 2: Unique Hazards & Fire Protection Requirements
Another key differentiator in the design of battery manufacturing facilities is the ability to manage the unique hazards posed by the battery cells themselves. Understanding state of charge (SOC) is key to creating a safe working environment. During the manufacturing process, if cells get above 35 to 50 percent SOC, they must be treated as a fire hazard due to the energy density in a large number of stored cells. A manufacturing defect in a cell above 35 percent SOC, for instance, can create thermal runaway that will spread to nearby cells initiating a chain reaction.
Mitigation measures include elaborate fire protection systems such as gas detection equipment that identifies problems before thermal runaway occurs, extensive in-rack sprinkler systems, and even heat-seeking water cannons that target temperature increases before a fire starts. These systems are combined with more traditional life safety tools, such as firewalls separating different hazard classified areas.
Because of the unique nature of these plants, US building codes are only just now being developed for lithium-ion battery manufacturing. Previously, the codes were only established for battery storage systems and not for the manufacturing process. Therefore, it is important at the beginning of a project to prepare a life safety plan and fire protection approach for review with the local building and fire officials.
Challenge No. 3: Liaising with Process Equipment Vendors
Because the US is still catching up to battery-manufacturing technology, most of the process equipment that’s being installed in US battery manufacturing facilities comes from China, South Korea, and Japan. This means communicating across language barriers and time barriers—and many early-morning or evening meetings.
A big part of this challenge is technical translation. Ideally, you need engineers on your team who can bridge the language barrier. If they are not available a translator is necessary. However, a pure translator is not particularly effective since they don't know the technical nuances and therefore can’t translate the meaning. For this reason, it is critical to have someone on your team who’s not only technically experienced but also has the required linguistic skills.
Additionally, team members who are not bilingual need to appreciate the difference between what is said versus what is meant. This drives home the importance of patience and taking the time to truly understand what is being discussed—on both sides.
Video calls are important in bridging the language gap. When you see someone, even if you’re not speaking the same language or there's a translator between you, you can watch their body language, which is extremely valuable. Additionally, never understate the value of graphics—a picture is worth a million words when you’re trying to communicate across language barriers. Lastly, building in extra time for meetings is crucial. Bilingual technical meetings take at least twice as long as you would normally expect.
Challenge No. 4: High Electrical Demands
The final challenge when designing a large-scale battery manufacturing plant is very high electrical demands. In addition to normal manufacturing electrical demand, the formation stage of battery manufacturing requires the charging and discharging of each battery cell. This drives an unusually high electrical demand for these facilities, which will likely necessitate a new, dedicated substation. New substations require very long lead times, which will drive your schedule.
“Power-On” becomes a crucial date. Therefore, your team must have the ability to rapidly understand the electrical need and coordinate effectively with the utility supplier. These suppliers are often their “own masters” and operate independently of other governmental agencies. They are not used to working at the speed required by large-scale manufacturing operations. Bottom line—bring both your hard- and soft-skill sets to the table when coordinating with the utility company.
A Recipe for Success
To effectively develop battery manufacturing plants, you need to successfully combine these four key challenges, which will evolve as technology advances. Already, we are exploring the direction these facilities might take over the next 10 years, such as smaller dry room environments, less intensive power use combined with recycling, significantly different building codes, and more sophisticated fire protection systems to name just a few of the advances we see on the horizon as we power toward an electric future.
David Verner, RA, NCARB is an executive vice president of Industrial at Gresham Smith, an architectural design firm located in the US.