Anatomy of a metal-air battery

Indian Oil Corp. and Israel’s Phinergy are developing metal-air batteries that capture oxygen in the air and, together with water and aluminium, create a reaction that generates electricity


Prototype battery: Contains 25kg of aluminium. 
Pack of four batteries can release enough energy, via chemical reaction, to drive 3,000km


Multiple cells
Each cell about 40mm thick


Cell 

Anode
Aluminium

Cathode
With silver-based catalyst

Electrolyte 
Water and potassium hydroxide


1. Porous cathode: Oxygen is separated from air by catalyst and passes into electrolyte.
Carbon dioxide is blocked

2. Electrolyte: Oxygen reacts with water to produce negative hydroxide ions

3. Anode: Oxygen and hydroxide ions react with metal, forming aluminium hydroxide and releasing electrons


CO2 O2 1 H20 H20 2 OH- OH- AL(OH)3 3 
 
Flow of electrons produces electricity


Aluminium anode: Eventually becomes corroded by electrolyte. Indian Oil plans to use its 35,000 service stations for high-speed replacement of spent batteries


Sources: Phinergy, Indian Oil Corp., PRNewswire 
Picture: Tata Motors 
© GRAPHIC NEWS