Essential Insights on Humidity Control in Battery Production

As the demand for advanced rechargeable batteries continues to surge with the green energy transition, precise humidity control in battery manufacturing has become increasingly crucial. To explore this vital aspect of the industry, Battery Technology spoke with Courtney Erickson, Business Development Manager at Vaisala. Erickson sheds light on how advanced dew point instruments can optimize the energy-intensive processes in battery manufacturing, such as cathode drying. In this interview, she discusses the challenges of maintaining ultra-low humidity environments, the limitations of traditional measurement solutions, and how Vaisala is addressing these issues to enhance efficiency, safety, and cost-effectiveness in the production of rechargeable batteries.

Business Development Manager for Vaisala Courtney Erickson. Courtesy of Vaisala.

How do innovations in dew point measurement specifically enhance safety and yield in rechargeable battery manufacturing?

Erickson: Vaisala was established in 1936, and over the past 88 years, our measurement technologies have evolved alongside the industries we support. Cathode coating, for example, must be performed in a dry room with very tight humidity controls and often under sweltering process air. The combination of extremely dry air at a high temperature can be challenging for any sensor — especially when harsh chemicals are also present.

Related:Solutions for Continuous Manufacturing of Battery Materials

It is no secret that the chemicals used in battery production are sensitive to moisture and, in some cases, present an explosion risk if exposed to elevated humidity levels. Reliable sensor technology can help prevent unwanted reactions, including lithium-forming lithium hydroxide and hydrogen gas, lithium salt forming hydrogen fluoride, and electrolyte-generating corrosive byproducts.

The highly sensitive and fast-reacting sensors optimize production conditions. By maintaining optimal dryness levels in ambient dry rooms and avoiding over- or under-drying, these innovations help manufacturers maximize their yield and product performance.

Uncontrolled humidity levels during production and storage will negatively impact the quality and, therefore, the lifetime of batteries. By providing real-time, accurate measurements, Vaisala’s highly sensitive and fast-reacting sensors help optimize energy consumption by maintaining optimal dry room ambient dryness and avoiding extremely costly over- and underdrying. 

What are the key challenges and inefficiencies associated with traditional humidity measurement solutions in battery manufacturing environments?

Erickson: The primary challenge is that traditional humidity measurement sensors often lack the sensitivity for the ultralow moisture conditions required in dry rooms and gloveboxes. High-quality humidity sensors with accuracy specifications of ±1% or even ±0.8% relative humidity (RH) are insufficient in these conditions. Maintaining the desired low humidity level with strict control in dry rooms or glovebox operations ensures components such as electrolytes are safe from decomposing.

Related:New Battery Sensor Detects Thermal Runaway Incidents Seven Minutes Faster

The lower the process dew point, the higher the uncertainty when using traditional humidity sensors. Courtesy of Vaisala.

As the figure illustrates, the lower the process dew point, the higher the uncertainty when using traditional humidity sensors. Increased uncertainty makes maintaining the precise control needed for safe and efficient production difficult. Vaisala dew point transmitters are explicitly designed for trace levels of moisture in the air, and our patented autocalibration technology can ensure an excellent accuracy specification of ±2°C in most installations.

Plus, many conventional humidity sensors are not designed to operate effectively across the full range of conditions encountered in battery manufacturing, from extremely dry environments with harsh chemicals to potentially high-temperature processes. Traditional sensors may experience calibration drift over time, while others may have slower response times, which can be problematic in dynamic manufacturing environments where rapid adjustments might be necessary.

In what ways do Vaisala’s dew point instruments address the unique demands of ultra-low humidity and high-temperature conditions in battery production?

Erickson: Stable dry room and dry booth conditions are crucial to product quality and plant safety in battery production. The temperature and moisture-controlled environments in production dry rooms have tight specifications for ultralow humidity, from 5%RH to below 0.5%RH or -60°F/C dew point in some cases. Since these operations rely on highly accurate measurement instruments with a fast response time, Vaisala’s sensors are installed directly into the process conditions, ensuring continuous monitoring without downtime due to complex internal measurement control loops, pumps, or bulky equipment.

Unlike conventional dew point instruments, Vaisala’s DRYCAP sensing technology can recover from condensing conditions and exposure to the harsh chemicals often present in this environment. Off-gassing from chemicals used during production can significantly decrease the life expectancy of most sensors. Vaisala’s patented autocalibration function enhances measurement stability in dry conditions by periodically heating or purging the sensor and monitoring its recovery. As the sensor cools to ambient temperature, offset correction compensates for potential drift, ensuring long-term measurement accuracy and significantly reduced maintenance needs.

Can you provide examples of how improved dew point measurement has led to tangible improvements in energy efficiency during processes like cathode drying?

Erickson: In some cases, up to 80% of the energy used in battery manufacturing is attributed to dry room and dryer operations.¹ Vaisala’s DRYCAP sensor innovations help manage and reduce energy usage while improving production efficiency. The highly sensitive measurement and quick response time mean dry rooms, booths, dryers, and glove boxes all maintain the right humidity. This precision ensures that energy is not wasted on excessive drying while retaining the required low humidity levels, which leads to poor product quality and increased safety hazards.

¹Heimes, H., Kampker, A., Lienemann, C., Locke, M., and Offermanns, C. (2019a). Lithium-ion Battery Cell Production Process.  

What are the broader implications of these innovations for the future of rechargeable battery technology and green energy initiatives?

Erickson: As we look ahead to the future, Vaisala is committed to improving efficiency not only in our production facilities and processes but also in those of our customers and partners. Rechargeable battery technology is a key element of our planet’s green transition, so these innovations are poised to enhance the efficiency and sustainability of battery production. Technologies such as Vaisala’s DRYCAP sensors will allow large battery production plants to better control their drying systems with extreme precision, thus saving energy while simultaneously minimizing losses and waste. This dual benefit of energy savings and waste reduction aligns with the overarching goals of green energy initiatives, making battery production more environmentally friendly and cost-effective. As production processes become more refined and reliable, manufacturers can focus on pushing the boundaries of battery technology, potentially leading to innovations with higher energy densities, longer lifespans, and improved safety profiles. Vaisala’s technology and innovation enable production efficiency now and in the future.