1. Why Temperature Is a First-Class Design Variable
Most teams prioritize chemistry, capacity, or energy density, but temperature is the silent constraint behind all three.
Lithium-ion cells are sensitive to:
- cold temperatures (slower discharge, voltage drop, reduced power output)
- high temperatures (accelerated aging, gas generation, swelling)
- rapid temperature swings (mechanical stress + SOC inaccuracies)
A product may pass bench tests and still fail in the field if its thermal profile wasn’t considered early.
2. Selecting the Right Chemistry for Temperature Extremes
Different chemistries behave very differently under thermal stress.
Here are general tendencies:
- NMC: strong performance but narrower safe-temperature ranges
- LFP: very stable thermally, but limited in ultra-cold use unless insulated/heated
- Li-ion Polymer: flexible form factors, but sensitive to high-temp environments
- Li-SOCl₂ (primary): excellent cold performance for long-life IoT devices
- Li-MnO₂ (primary): stable across a wide temperature range, ideal for pulsed loads
There is no universal “best” chemistry; there is only the best chemistry for a specific mission profile.
3. Designing for Cold Temperatures
Cold impacts performance more than any other condition.
Here are some engineering considerations:
- remove air gaps in the enclosure
- incorporate thermal pads or insulation layers
- pre-warm strategies for extreme cold
- BMS discharge current limits based on temperature
- voltage cutoff adjustment for cold-weather use
- select cells tested and graded for low-temperature behavior
4. Designing for High Temperatures
Heat accelerates almost every aging mechanism inside a cell.
Design strategies include:
- selecting chemistry with proven high-temperature cycle stability
- designing airflow paths or venting in the enclosure
- spacing cells to prevent localized hotspots
- using thermal barriers between cells
- implementing BMS over-temperature throttling
- considering potting materials carefully (many retain heat)
High temperatures often lead to swollen cells and reduced lifespan, which are both preventable.
5. Preventing Thermal Runaway
For devices operating in elevated temperatures, prevention starts with:
- cell spacing
- thermal interface materials
- flame-retardant insulators
- proper venting pathways
- sensors placed near the hottest part of the pack
- conservative charge/discharge limits
Thermal runaway is rare in well-engineered packs, but only with proper mitigation designed in from day one.
6. Enclosure Design Matters More Than You Think
Many real-world failures are caused by enclosure decisions, not cells.
Key considerations:
- sealed vs. vented design
- how much heat the enclosure traps
- exposure to sunlight
- thermal expansion allowance
- waterproofing vs. heat dissipation trade-offs
The enclosure can make a battery fail or keep it perfectly stable.
7. Field Testing: The Final Proving Ground
You can't validate thermal performance on a desk.
We recommend:
- temperature cycling (cold ↔ hot)
- prolonged soak tests
- load testing at temperature extremes
- accelerated aging under heat
- verification of BMS behavior across temp ranges
- validation of SOC accuracy under cold conditions
Real-world environments always reveal what lab conditions hide.
Temperature dictates whether a battery ages gracefully or fails quickly.
If you're planning a device that needs to survive heat, cold, or both, our engineering team can support you from early strategy through validation.
