The rapid development of energy storage systems, particularly electrochemical energy storage battery, has become pivotal in addressing grid stability and renewable energy integration. Among these, lithium-ion energy storage battery dominate due to their high energy density, long cycle life, and cost-effectiveness. However, their dense configuration in industrial and commercial settings exacerbates thermal management challenges, leading to risks of thermal runaway and subsequent fires. This article synthesizes experimental insights into the parameter characteristics of thermal runaway in energy storage battery and evaluates mitigation strategies, emphasizing gas-based fire suppression systems.
Thermal Runaway Mechanisms in Energy Storage Battery
Thermal runaway in lithium-ion energy storage battery is typically triggered by mechanical damage, electrical faults, or thermal abuse, resulting in internal short circuits. The process evolves through three phases:
- Initial Stage: Abnormal temperature rise and current fluctuations.
- Intermediate Stage: Battery deformation and release of pyrolytic gases (e.g., CO, H₂, CH₄).
- Final Stage: Smoke, open flames, and potential explosions.
The energy release during thermal runaway follows an exponential temperature rise, approximated by:T(t)=T0+α⋅eβtT(t)=T0+α⋅eβt
where T0T0 is the initial temperature, and αα, ββ are coefficients dependent on battery chemistry and fault conditions.
Experimental Setup and Data Acquisition
A simulated thermal runaway experiment was conducted using a 20-foot standard container housing a 1000 × 800 × 240 mm lithium iron phosphate (LFP) battery pack. Key components included:
- Heating System: Two 1 kW heating pads to induce thermal abuse.
- Sensor Network: 17 temperature sensors, 10 multi-parameter detectors (CO, VOC, smoke, temperature).
Key Parameters Monitored
| Parameter | Sensor Type | Measurement Range | Critical Thresholds |
|---|---|---|---|
| Temperature | Thermocouples | -40°C to 1000°C | 80°C (alarm threshold) |
| CO Concentration | Electrochemical | 0–2000 ppm | 190 ppm (low alarm), 500 ppm (high) |
| VOC | Semiconductor | 0–5 V | 2.5 V (alarm threshold) |
| Smoke Density | Photoelectric | 0–100% obs/m | 15% obs/m (alarm threshold) |
Thermal Runaway Progression and Fire Dynamics
The experiment revealed critical timelines and parameter trends during thermal runaway:
Timeline of Events
- 10 min 59 sec: CO concentration reached 194 ppm (low alarm).
- 37 min 25 sec: Battery swelling and audible cracking.
- 39 min 27 sec: Smoke intensification and open flames.
- 51 min 31 sec: Fire suppression achieved using perfluorohexanone.
Temperature and Gas Concentration Trends
- CO Concentration: Peaked at 1513 ppm (sensor saturation) during the final stage.
- Temperature: Localized spikes exceeding 725°C near heating pads, while adjacent regions remained below 30°C.
The spatial heterogeneity of temperature and gas dispersion underscores the importance of sensor placement. For instance, the internal detector (No. 1) provided early CO warnings 18 minutes before visible flames, whereas external detectors lagged.
Gas-Based Fire Suppression Efficacy
Conventional liquid fire suppression systems risk electrical shorts in energy storage battery. Gas-based alternatives, such as perfluorohexanone (C<sub>6</sub>F<sub>12</sub>O), offer advantages:
- Low Toxicity: Minimal environmental and human health impact.
- Rapid Cooling: Absorbs heat via vaporization, reducing reignition risks.
The灭火 efficiency (ηη) of perfluorohexanone depends on enclosure volume (VV) and agent concentration (CC):η=C⋅Vk⋅Tη=k⋅TC⋅V
where kk is a proportionality constant, and TT is the ambient temperature.
Comparison of Fire Suppressants
| Agent | Toxicity | GWP* | Decomposition Temp. | Suitability for Energy Storage Battery |
|---|---|---|---|---|
| Perfluorohexanone | Low | 1 | 550°C | High (early/mid-stage fires) |
| HFC-227ea | Moderate | 3500 | >800°C | Moderate (limited by environmental impact) |
*Global Warming Potential (GWP) relative to CO<sub>2</sub>.
Critical Insights and Recommendations
- Early Detection: CO monitoring within energy storage battery packs enables 18-minute lead time for intervention.
- Sensor Optimization: Deploy multi-parameter detectors at strategic locations (e.g., near heating sources).
- Gas Suppression: Perfluorohexanone achieves rapid flame extinction in enclosed spaces (e.g., 20-foot containers) with minimal collateral damage.
Key Challenges
- Heat Localization: Thermal runaway generates extreme localized temperatures (>700°C), demanding robust material design.
- Agent Dosage: Optimal perfluorohexanone dosing requires further study to balance efficacy and cost.
Future Directions
- Advanced Modeling: Develop predictive algorithms for thermal runaway using machine learning and real-time sensor data.
- Material Innovation: Explore flame-retardant electrolytes and separators to delay ignition.
- Standardization: Establish unified safety protocols for energy storage battery deployment.
Conclusion
Energy storage battery is indispensable for modern power systems, yet their thermal runaway risks necessitate rigorous safety measures. This study validates the effectiveness of gas-based suppression systems like perfluorohexanone in mitigating fires, while emphasizing the role of early CO detection. Future advancements in sensor technology and material science will further enhance the safety and sustainability of energy storage battery, ensuring their pivotal role in the renewable energy transition.