Extreme Heat and Electric Vehicle (EV) Batteries

Context

Electric vehicle (EV) owners are increasingly concerned about the impact of extreme temperatures on lithium-ion batteries. These batteries function optimally at ambient temperatures up to 35 degrees Celsius. Lithium-ion batteries are particularly heat-sensitive, while solid-state batteries exhibit greater resilience.

Impact of Extreme Heat on Lithium-ion Batteries

1. Longevity Loss: High temperatures accelerate the flow of ions in a battery, causing premature aging due to unwanted chemical reactions.
2. Thermal Runaway: Extreme heat exposure can lead to thermal runaway, a dangerous condition that can cause fires.
3. Efficiency Loss: The overall efficiency of the battery system drops in extreme heat as electrochemical, electrical, and electronic components all get heated.
4. Thermal Stability Variations: Among lithium-ion batteries, the lithium iron phosphate (LFP) chemistry is more thermally stable compared to lithium cobalt oxide (LCO) or lithium manganese oxide (LMO) chemistries.
5. Design Vulnerabilities: Battery packs in electric two-wheelers are generally more susceptible to heat-related issues due to their densely populated design, unlike three- and four-wheelers which can incorporate more efficient liquid cooling systems.

Efforts to Address the Issue

1. Cooling Systems: Both air- and water-based cooling systems are implemented to mitigate the effects of increased ambient temperatures.
2. Insulation: Proper insulation materials and thickness can keep cells cooler by 5 to 7 degrees Celsius compared to the surrounding environment.

Testing Standards for EV Batteries

1. AIS-156 and AIS-038 Standards: These standards, developed in response to EV fires in 2022, mandate the inclusion of battery management systems (BMS).
2. Advanced BMS Technologies: The latest BMS technologies use predictive algorithms and real-time temperature monitoring for each cell. They can redistribute power from hotter cells and proactively activate cooling systems.
3. Venting Systems: Battery packs are required to have a venting system to allow hot air to escape, thereby preventing fire propagation.
4. Temperature Testing: AIS-038 standards recommend that battery packs be tested at 45 degrees Celsius to assess their performance under high-temperature conditions.

Concerns with Testing Standards

1. Drive Cycles and Fast Charging: Testing should encompass various drive cycles and include fast charging scenarios to accurately validate a battery’s thermal performance under real-life conditions.
2. Longevity Evaluation: EV manufacturers need to evaluate battery longevity under conditions that closely mimic real-world scenarios.

Localisation: A Promising Solution

1. Customised R&D: Research and development conducted outside India or any advanced cell chemistry (ACC) battery developed in different climatic conditions may not be suitable for India’s extreme heat. Localised R&D is essential.
2. Environmental Differences: The environments in China and India differ significantly, making direct technology transfers ineffective.
3. Local Manufacturing: Faster iteration based on real-world data is possible with local manufacturing, ensuring technology is tailored to Indian conditions.
4. Support Programs: The Production Linked Incentive scheme and the National Programme on Advanced Chemistry Cell (ACC) Battery Storage aim to promote the development of customised battery technologies.

Advanced Cell Chemistry (ACC)

ACCs represent advanced storage technologies that store electric energy as electrochemical or chemical energy and convert it back to electric energy as needed. This adaptability makes ACCs crucial for the future of EV battery technology, particularly in extreme heat conditions.