South Korean firm Kokam’s lithium nickel manganese cobalt batteries were at the heart of record-breaking journey around the world.
Battery powered Solar Impulse 2 was the first plane to circumnavigate the globe using just solar power when it completed its journey last month.
The plane used four 38.5kWh Kokam Ultra High Energy NMC battery packs with 150 Ah cells, totaling 154 kWh of energy storage.
Kokam’s batteries boast an energy density of around 260 Wh/kg.
During the 26,744 mile (43,041 km) flight the plane’s 17,248 solar cells produced 11,000 kWh of electricity, which was stored in the batteries for use at night.
André Borschberg, co-founder, CEO and pilot of Solar Impulse, said: “What was critical was to get the lightest and most energy efficient solution, and we consequently selected Kokam’s Ultra High Energy NMC batteries, which has been our battery solution since the first flight of Solar Impulse 1 in December 2009 until the final leg landing of Solar Impulse 2 in Abu Dhabi in July 2016.”
But it wasn’t all ‘plane’ sailing. During the leg from Japan to Hawaii the batteries were heated to 50 degrees Celsius for an extended period of time – a temperature higher than the design specifications.
Because it was impossible to rule out capacity loss or other damage the batteries were replaced.
Post flight tests of the original batteries at a facility in Germany subsequently found the batteries were undamaged, with only a ‘normal’ amount of capacity fade compared to their original state in November 2013.
