Keywords: LiFePO4 high temperature, thermal aging, lithium battery overheating, ESS safety
LiFePO₄ chemistry offers excellent thermal stability compared to other lithium-ion types, but high temperatures still pose significant risks. Continuous exposure to heat accelerates chemical aging and decreases cycle life.
1. The Effects of High Temperature on Cycle Life
Operating above 35–40°C accelerates several aging mechanisms:
- Faster SEI growth
- Increased electrolyte oxidation
- Higher self-discharge rate
- Capacity fade
- Higher internal resistance
A LiFePO₄ battery rated for 6000 cycles at 25°C may see:
- 4500 cycles at 35°C
- 2500–3000 cycles at 45°C
2. Thermal Expansion and Structural Stress
High temperatures cause:
- Electrode expansion
- Increased mechanical stress
- Reduced structural stability
Over long cycles, this reduces performance and weakens internal materials.
3. Safety Implications
Unlike NCM/LCO batteries, LFP is unlikely to experience thermal runaway.
However:
- BMS may shut down to prevent overheating
- Excessive heat can damage MOSFETs and control electronics
- Charging at high temperatures can produce gas inside cells
4. Common Causes of Overheating
- Poor ventilation
- Direct sunlight on wall-mounted batteries
- Enclosed metal cabinets
- High discharge currents
- Faulty inverter placement blocking airflow
5. Tips for Reducing Heat Stress
- Install ESS in cool, dry, shaded locations
- Maintain ventilation around racks and cabinets
- Avoid oversizing the inverter relative to the battery
- Use BMS-activated temperature alarms
6. Conclusion
High temperatures significantly shorten the lifespan of LiFePO₄ ESS batteries. Proper installation and ventilation ensure consistent performance and safety.