With the rise of electrification and the shift towards green energy, the demand for more powerful and safer rechargeable batteries—such as lithium-ion, sodium-ion, and solid-state—is rapidly growing. Manufacturing these batteries is a delicate process performed in highly controlled, ultra-low humidity environments. So how can accurate, highly responsive dew point probes help to increase safety, yields, and energy efficiency?

The midstream stage of battery manufacturing involves electrode production, cell assembly, and cell finalization. It is during these steps – in dry rooms, dry booths, and glove boxes – that humidity control is especially important to prevent unwanted reactions. These include lithium forming lithium hydroxide and hydrogen gas, lithium salt forming hydrogen fluoride (HF), and electrolyte generating corrosive byproducts. The more efficient and effective the drying (in other words, the better it is controlled) the more you can:

• protect the safety of people and materials, since the chemicals used are sensitive to moisture and present an explosion risk if exposed to elevated moisture levels
• maximize the yield of the process and maintain quality, as excessive moisture will negatively impact the quality and therefore the lifetime of batteries 
• optimize energy consumption by maintaining dry room ambient dryness at optimal levels, avoiding over-drying and under-drying, both of which are extremely costly
   

Accurate, responsive dew point measurement is critical for drying – especially in solid-state battery manufacturing 

The ambient dew point temperature in dry rooms is maintained at around -30 ºC to -40 ºC. Low humidity is controlled by a high-end dryer that pushes dry air into the room. This is one of the most energy-intensive parts of the whole battery manufacturing process, so minimizing over-drying is key to the plant’s overall energy efficiency. 

The dew point sensors in the dryer need to be highly responsive to control the dryer quickly and accurately in order to avoid under or over-drying. It is important to note that sensor accuracy alone will not be enough to avoid these issues. A probe with a fast response time, and without the complex internal measurement control loops of some analyzers, makes all the difference in dryer and overall dry room control. The volume of air being dried and pushed through is huge, so the energy consumption can easily skyrocket if the drying process is not optimized. 

Newer technologies such as all solid-state batteries may require drier conditions with the dew point temperature as low as -80 ºC in individual processing steps. These steps are usually performed inside dry booths or glove boxes because it is not economical to dry the whole dry room to the same extremely low dew point level. Humidity levels in dry booths and glove boxes are monitored at critical points. 

Vaisala’s DRYCAP® technology is the world’s most used technology for dryer monitoring and control. It is a field-proven innovation that provides accurate, stable, and fast-response dew point measurement with minimum drift. Vaisala has achieved this leading position not just because of innovation, but also because of a firm commitment to product quality and reliability, with short lead and delivery times, combined with world-class levels of service. 

Versatile, cost-effective solutions for the whole process

The sensors needed to monitor humidity in the drying process of midstream battery manufacturing don’t need to be expensive ultra-high precision laboratory-level devices. For example, the miniature dew point transmitter DMT143 is a simple, cost-effective device for accurate, stable, and fast-response dew point measurements in air dryers and glove boxes. 

Vaisala adds value by providing holistic systems and packages, such as the Vaisala Indigo ecosystem. The core of the Indigo offering is the transmitters and compatible probes with DRYCAP® technology. Indigo family products are versatile and easy to install, use, and service. Transmitters that support various fieldbuses and include built-in displays and other advanced features can be combined with probes such as the DMPx. This enables you to measure accurately and reliably in demanding processes with harsh chemicals, high temperatures, and ultra-low humidity. This is why the Indigo ecosystem offers the best solution for humidity monitoring and control in midstream battery production. 

Vaisala has been the industry leader in humidity measurements for over 50 years, with innovative products enjoying a global reputation for accuracy, reliability, long-term stability, and fast response times. Long product lifecycles and warranties, as well as industry-leading technical support, mean you can rest assured that Vaisala will help you increase safety, yields, and energy efficiency in midstream battery production for many years to come.