Contributed Commentary by Courtney Erickson, Vaisala
October 18, 2024 | From our vehicles and laptops to our smartphones, remote controls, and the toys our kids play with, batteries help power our daily lives. Growing requirements for innovative energy storage solutions pressure manufacturers to ramp up rechargeable lithium-ion, sodium-ion, and solid-state battery production while maintaining the delicate balance required for efficient and safe manufacturing processes.
From electrode production to cell finalization, this crucial technology sector demands efficient humidity control and measurement systems that can withstand extreme conditions. When cathode drying alone can consume up to 45% of the total energy used in a dry room, any inefficiencies can lead to significant problems: increased production costs, reduced battery quality, and potential safety hazards. Enter accurate dew point measurement as an ideal parameter for optimizing battery manufacturing.
Battery Manufacturing Challenges
Rechargeable battery manufacturing is a complex process. In the race for shorter charging times or reduced battery weights, disparate challenges plague the battery manufacturing process. The midstream stage of battery production—electrode production, cell assembly, and cell finalization—is susceptible to moisture. Even minuscule humidity levels can trigger unwanted reactions compromising battery quality and safety, necessitating highly controlled, ultralow humidity environments like dry rooms, dry booths, and glove boxes.
Cathode drying is a crucial but costly step in electrode manufacturing, especially if not optimized. Timely drying of electrodes mitigates potential battery performance degradation, as residual moisture and impurities from the solvent can jeopardize their functionality.
Inconsistencies in manufacturing electrode layers can significantly diminish cell and module performance, leading to reduced capacity or capacity degradation over time. Drying also influences the thickness and porosity of electrodes, critical factors affecting both capacity and internal resistance. Traditionally, humidity measurement solutions have been bulky, high-maintenance devices that struggle to withstand extremely low moisture levels and high temperatures, underscoring the critical need for robust and efficient humidity control and measurement solutions.
Process Optimization for Humidity Control
Effective drying processes are crucial for several reasons:
- Safety: The chemicals used in battery manufacturing are highly sensitive to moisture and pose explosion risks if exposed to elevated humidity levels.
- Quality and yield: Maintaining optimal humidity levels throughout manufacturing helps maximize yields and ensure consistent product quality and lifetime.
- Energy optimization: Maintaining optimal dry room ambient dryness avoids costly over-and underdrying.
Typical battery manufacturing environments, such as dry rooms, maintain the ambient dew point temperature between -30°C and -40°C via high-end dryers continuously pushing dry air into the room. Newer technologies like solid-state batteries may require even drier conditions, with dew point temperatures as low as -80°C in individual processing steps.
Achieving and maintaining such extreme low humidity levels throughout an entire dry room is not economically feasible. As a result, manufacturers often utilize dry booths or glove boxes for these specific processes. Even in these enclosed environments, humidity levels must still be carefully monitored to maintain optimal conditions.
Consequently, dew point sensors in the dryer must be highly responsive, enabling quick and accurate control at each manufacturing stage. However, sensor accuracy alone cannot avoid issues like under- or overdrying. Probes with fast response times without complex internal measurement control loops significantly affect the dryer and overall dry room control.
Industrial Measurement Best Practices
Industry leaders are adopting several key strategies to optimize battery manufacturing processes, including using dew point measurements for process optimization since temperature does not affect dew point. Similar measurement products and parameters across different drying stages deliver comparable results and easier process optimization. Selecting probes with excellent chemical tolerance and rapid response time also helps maintain accurate measurements. Strategic sensor placement and monitoring of humidity levels across multiple stages of the drying process unlock comparable results at different stages, driving fine-tuned control and optimization.
Fortunately, recent innovations have led to the development of highly responsive, accurate, and low-maintenance dew point instruments that enhance manufacturing processes in several ways:
- Improved accuracy: New sensor technologies offer excellent measurement stability in even the most demanding conditions, ensuring precise control.
- Fast response time: Quick response to humidity changes reduces energy waste and improves product consistency.
- Chemical tolerance: Advanced sensors can withstand exposure to harsh chemicals—like N-Methyl-2-pyrrolidone (NMP) solvent—increasing reliability and reducing maintenance needs.
- Heat durability: Sensors capable of operating at high temperatures (up to 160°C in some cases) allow in-situ measurements in challenging drying environments.
- Minimal drift: Stable measurements over time reduce the need for frequent recalibration and production downtime.
Battery manufacturers can minimize one of the most significant cost drivers without sacrificing product quality by targeting exactly needed levels of dryness to optimize the heat used during this process.
Powering the Path Forward in Battery Manufacturing
As the battery industry continues evolving to meet modern needs, advanced measurement technologies in manufacturing processes can help overcome the challenges of humidity control. Addressing battery production challenges with cutting-edge dew point measurement solutions helps manufacturers improve energy efficiency, product quality, and even the safety underpinning the technology’s sustainable growth.
Since the drive toward more sustainable and efficient battery production aligns with the world’s broader goals for renewable energy and reduced carbon emissions, implementing highly responsive, accurate, and low-maintenance dew point instruments is just the beginning. Optimizing manufacturing processes empowers the industry to reduce its environmental footprint while contributing to producing more efficient and longer-lasting batteries and a future powered by cleaner, more efficient energy solutions.
Courtney is a Sales Manager and Measurement Expert in Vaisala’s Boston office and supports customers throughout North America. Her primary focus is business development within the semiconductor and battery industries. She holds a bachelor’s degree in biomedical engineering and a master’s degree in management, which she earned during her 9+ years with Vaisala. She can be reached at Courtney.Erickson@vaisala.com.
