Maximum,meaning the most. And ion,which is an atom or group of atoms with an electrical charge.

VOA: special.2010.05.30

The new technology is called ion concentration polarization.

VOA: special.2010.04.05

"We will use the tremendous capabilities of this ion propulsion system to climb out of orbit around Vesta, travel for almost another three years through the asteroid belt to dwarf planet Ceres and then go into orbit around Ceres and undertake the same kind of measurements there that we'll be doing at Vesta.

VOA: special.2011.07.27

(SAYING) Here at the GM battery lab, the Volt's 16 kilowatt lithium ion batteries are run through the rigors of extreme driving,weather fluctuations and abrupt movements.

VOA: standard.2010.07.30

"The power source for the aircraft are the two battery packs you see on either side, which are lithium ion batteries which are similar to what you find in our laptops, only custom made for us for this application."

VOA: standard.2010.08.11