The slow demise of Li-air batteries for electric cars

Yet another development in the electric car industry: IBM and Joint Center for Energy Storage Research lab (JCESR) funded by US-government announced that they would unwind their research titled “Battery 500 Project” for lithium-air batteries which started back in 2009.

The director of this project, Winfried Wilcke, announced his new-found fondness towards sodium-air batteries instead of lithium-air ones. He believes now that the sodium equivalents would be more economically competitive as compared to the lithium-air ones.

Here’s a table of comparison for the different types of electric car batteries:

 Type Lithium-air batteries (2009) Lithium-ion batteries (1991)

Sodium-air batteries

 What
  • Oxygen interacting with Lithium to generate electricity.
  • Cathodes like cobalt
  • Most common in electric cars
  • Oxygen interacting with Na to generate electricity.
 Pros
  • 500 mph on single charge
  • Cheap carbon cathode
  • Higher energy density than Li-ion and Na-air batteries
  • High energy density
  • Very stable
  • NaO2 formed and decompose into Na, O2 which is reversible process, efficient
  • Na cheaper & more abundant than Li
 Cons
  • Relatively unstable
  • Production of waste product lithium carbonate
  • Added weight and cost due to the need to maintain conditions of the electrodes


  • 100 mph on single charge
  • Expensive metal oxide cathode
  • Energy capacity/storage life depletes after each cycle.
  • Can only recharge approx 10 times.

Batteries Comparison Table ©The Green Plebeian

What happens during battery discharge:

  • The metal (Na or Li) is oxidized at the anode/electrolyte interface, and the resulting electron is transferred to the outer circuit. At the cathode, oxygen is reduced to a superoxide species that may form a metal superoxide in the presence of the oxidized metal.
  • The metal superoxide in a Li-oxygen cell is highly unstable and reacts further.
  • The metal superoxide in a Na-oxygen cell is much more stable and doesn’t decompose further, allowing the reaction to be reversed.

Speaking to an Electrical Engineering friend of mine, I found out that research and development in the clean battery field is still lagging behind other renewables, partly because of the difficulty to make breakthroughs in its limitations. However, with the increasing rate of market expansion of electric cars throughout the world (See post on Tesla), the next generation of highly usable and efficient batteries could be well on its way to revolutionize the automobile industry.

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