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Battery Safety: What is Off-Gassing and Why Does it Occur?

17 July 2024

Batteries power many of our daily devices, from smartphones to electric vehicles. While battery technology advancements have transformed our lives, they also come with potential risks that need careful consideration.

Understanding Off-Gassing: The Silent Emission

Off-gassing refers to the release of gases from lithium-ion batteries, often due to damage, abuse, or misuse. Conditions such as overcharging, over-discharging, or physical damage can break down internal components, releasing gases like carbon dioxide, carbon monoxide, hydrogen, and volatile organic compounds. These gases are flammable and toxic.

Off-Gassing Dynamics and Risks

Off-gassing behavior varies based on battery design and deployment. In enclosed setups, off-gassing can build up, increasing pressure and ignition risk. In open or well-ventilated areas, the gases may dissipate more easily but still pose risks.

How and When Off-Gassing Occurs

Off-gassing often occurs early in battery failure, sometimes leading to thermal runaway—uncontrolled chemical reactions causing rapid temperature and pressure increases, expelling flammable gases, and potentially resulting in fires. The timeline varies: gradual off-gassing can occur from repeated stress, while sudden events like overcharging can trigger it instantly.

Factors Leading to Off-Gassing

  • Physical Damage: Punctures or crushing degrade internal components.
  • Overcharging: Decomposes electrolytes, generating gases.
  • Overheating: Destabilizes internal chemistry, triggering thermal runaway.
  • Over-discharging: Exceeds recommended limits, releasing gases.
  • Internal Short Circuits: Malfunctions causing short circuits can initiate thermal runaway.
  • Manufacturing Defects: Weaknesses from faulty processes increase susceptibility.

Dangers of Off-Gassing Buildup

Accumulated off-gassing can turn a battery container into a pressure vessel, posing a fire risk. Monitored ventilation systems and compliance with FM standards are essential, maintaining gas levels below 25% LFL or venting gas to ensure safety.

Importance of Early Detection

  • Preventative Maintenance: Early detection allows for timely maintenance and corrective actions, identifying issues like overcharging or internal damage.
  • Risk Mitigation: Monitoring off-gassing helps adjust charging parameters or isolate malfunctioning batteries, preventing thermal runaway.
  • Enhanced Safety: Early detection allows for evacuation, emergency protocols, and minimizes battery-related incidents.
  • Cost Savings: Proactive issue resolution extends battery lifespan, optimizes performance, and avoids costly repairs and unplanned downtime.
  • Regulatory Compliance: Monitoring off-gassing ensures compliance with safety protocols and industry standards.

MPS™ Sensor Technology – The Earliest Warning of Battery Runaway

NevadaNano’s Molecular Property Spectrometer™ (MPS™) gas sensor detects over a dozen combustible gases, including hydrogen, DMC, and EMC, with unprecedented reliability and accuracy featuring:

  • Detects DMC/EMC & H2
  • No Calibration required
  • Supports 15+ year lifetime
  • Immune to Poisoning
  • Built in Self-Test
  • Certified Intrinsically Safe

The detection capabilities of the MPS™ results in earlier stage detection of an issue within the battery P-F failure curve, prior to generation of other toxic & flammable gases

Summary

The MPS™ gas sensor provides advanced detection of gases during lithium battery off-gassing, enhancing safety measures and enabling proactive risk mitigation. Its comprehensive detection capabilities ensure reliable monitoring, safeguarding against hazardous situations, and contributing to a safer environment. The MPS™ Gas Sensor gives the earliest warning of battery runaway.

gas sensor, nevadanano, battery pack, lithium battery production, MPS technology

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