Gaseous Hydride Hazards & the High-Tech EV Revolution

By: Dr. Blaise Champagne, Contributorrrr

The manufacturing of chips and other high-tech electronics has helped drive the electric vehicle (EV) revolution. Common gas hazards monitored in electronic production processes include toxic hydrides, such as arsine (AsH3) and stibine (SbH3). Batteries provide the energy storage to power EVs, making them a key technology underlying the revolution.

Although the use of batteries is considered more environmentally friendly than fossil fuels, in terms of a carbon footprint, their use also gives rise to familiar environmental hazards such as hydride gas emissions–amongst others. In what is perceived to be a “green” revolution, let us explore this key power source and the toxic hydrides produced during the production and recycling of batteries.

Both AsH3 and SbH3 become toxic at quite low levels.1 AsH3 has a TWA exposure value of 0.05ppm and an IDLH of 3ppm1 and SbH3 a TWA of 0.1ppm and an IDLH of 5ppm.[1] Both substances target organs such as the blood, kidney and liver. Additionally, arsine is linked to certain cancers. This article discusses the measurement challenges that arise as the TLV values for these compounds are in the sub-ppm concentration range.

These gases arise during processes used to produce and recycle important non-
ferrous metals used in batteries, such as zinc and copper. Normally, a key part of the refining and purification processes is the addition of the ore or dirty recovered metal to sulfuric acid (H2SO4) solutions.  The ores or refined metals have trace amounts of arsenic (As) and antimony (Sb) contaminant in various chemical forms. The addition of sulfuric acid can cause a reaction to produce (AsH3) and/or (SbH3).

Measurement and Monitoring

Measuring these substances is quite challenging under the best of conditions. The toxic hydrides must be monitored at quite low values due to their toxicity at sub-ppm levels. When batteries are being produced and processed for recycling, these hazards are present in a demanding environment that is potentially very corrosive and dirty—and might have elevated temperatures plus high humidity.

There are highly effective technologies for measuring low-level hydrides that have been in use for some time in semiconductor manufacturing. The technology most often utilized for this is colorimetric tape analyzers. These colorimetric tape analyzers are able to measure hydrides down to low-ppb concentrations and have proven themselves to be quite dependable for these types of measurements over the years. However, implicit in semiconductor manufacturing are carefully controlled ambient conditions. Most semiconductor hydride measurements are recorded in environmentally controlled “clean rooms” with little or no dust, moisture or excess temperature.

Overcoming Challenges in Battery Production

Shown here is a colorimetric analyzer in combination with a sample system for gas sampling in a harsh industrial environment. (photo courtesy DOD Technologies, Inc.)

The key challenge to overcome for battery production and recycling is deploying precision colorimetric analyzers designed for clean, dirt-free environments, in less pristine sampling conditions associated with metal refining and recycling. To make these measurements without destroying the analyzer, the use of sample conditioning systems is required. The sample must be conditioned to ambient conditions of temperature, pressure, particulate concentrations and humidity so the analyzer is not destroyed.

A typical sample system that reduces dust and excess humidity, and provides sample cooling, is shown in the photo below. Although these systems can be quite complex, the underlying goal is straightforward. You need to draw a non-ambient gaseous sample and convert it to an ambient one in a reproducible way, so it can be measured by precision analyzers designed for clean, ambient atmosphere environments. This combination of ambient colorimetric analyzers and sample systems is being effectively utilized at battery manufacturing and recycling facilities; several high-profile players in this field have successfully implemented these types of solutions to address hydride hazards.

Based on current market trends, the requirement to monitor hydride emissions from battery production and processing will increase rapidly. For example, there are over 1,000lbs of batteries in a typical EV.[2] Driven by EVs and other consumer electronics, the global market size for rechargeable batteries is expected to grow from $44.49 billion in 2021 and is projected to reach $193.13 billion by 2028. That translates into a compounded annual growth rate of 23.3% during the forecast period from 2021-2028.[3]

The number of facilities that produce and recycle batteries will have to rapidly grow to keep up with the demands for manufacturing and recycling of rechargeable batteries. CATL, LG and Panasonic, estimated to control about 70% of the EV battery market, are currently planning capacity and plant expansions.[4]

In summary, hydride emissions from battery production and recycling are increasing in the workplace, driven by strong demand for the batteries used in EVs and other applications. The same colorimetric tape technologies that have been effectively utilized in the semiconductor industry, primarily in clean rooms, are effective at measuring these toxic hydrides. The technical challenge is that the conditions associated with battery production are often quite dirty and might have elevated temperatures and moisture associated with them. These issues are addressed with sample conditioning systems, bringing the sample to ambient conditions that will not harm the analyzer and allow accurate hydride measurements to be made—even under harsh sampling conditions.

About the Author

Dr. Blaise Champagne has 30+ years of experience in gas detection and related fields. He is the Business Development and European/Southern Territory Manager at DOD Technologies, Inc., a gas detection manufacturer specializing in low-level,  colorimetric-based gas-detection technologies.

[1]   See the NIOSH Pocket Guide to Chemical Hazards available online at the CDC website and in printed format.

[2]   Tesla Model 3, Wikipedia.org

[3]   Fortune Business Insights February 21, 2022

[4]    Spectrume.ieee.org, The Top 10 EV Battery Makers, August 25, 2021