Mains-GS-3-Technology

The Union government has constituted an expert panel to probe the recent series of battery explosions in electric vehicles (EVs).

Why is the world poised to transition to electric vehicles?

  1. Growing concern over climate change.
  2. Cost of Li-ion (Lithium-ion) battery technology has decreased compared to that of the last decade.
  3. Governments across the world are  providing incentives to usher in the transition.
  4. Private industry is ramping up plans for capturing the market.

What goes into a Li-ion battery?

  1. Every Li-ion battery consists of three active components:
(i)The anode, typically graphite; (ii)The cathode, typically based on a nickel, cobalt, and manganese-based oxide; (iii) An electrolyte, typically a salt of lithium in an inorganic solvent.
  1. Battery manufacturing involves forming sheets of the anode and cathode and assembling them into a sandwich structure held apart by a thin separator.
  2. Separators, about 15 microns in thickness, perform the critical function of preventing the anode and cathode from shorting.
  3. Accidental shorting of the electrodes is a known cause of fires in Li-ion cells.
  4. It is important that the various layers are assembled with high precision with tight tolerances maintained throughout the manufacturing process.
  5. Safety features like thermal switches that turn off if the battery overheats, are added as the sandwich is packaged into a battery cell.

Which are the causes of battery fires?

  1. Batteries store energy in a small package and if the energy is released in an uncontrolled fashion, the thermal event can be significant.
  2. Battery fires, like other fires, occur due to the convergence of three parts of the “fire triangle”: heat, oxygen, and fuel.
  3. An adverse event such as a short circuit occurs in the battery, the internal temperature can raise as the anode and cathode release their energy through the short circuit.

How to prevent fires?

  1. Preventing fires requires breaking the fire triangle.
  2. Battery cathodes are a leading cause of the heat release.
  3. Tightly controlled manufacturing will prevent accidental shorts in the cells, eliminating a leading cause of fires.
  4. Many companies now add a ceramic layer on the separator to mechanically prevent shorts.
  5. Battery packs need to be protected from external penetration.