You may remember High School chemistry class when the topic of reactive metals came up. My teacher had a big slab of pure sodium he kept in a jar under kerosene. The reason for that was to prevent any water, even humidity in the air from reacting with that pure metallic sodium. He would slice pieces off of the sodium to make the surfaces completely free of tarnish. Then pull out the pieces with forceps. And in a display of pyrotechnics and sound and fury, he would place the metal in a flask of water. And it would fizz violently racing around on the surface of the water. It was reacting with the water creating Lye (NaOH-Sodium Hydroxide) and Hydrogen Gas(H2). He would then light the gas to show it was really combustible Hydorgen gas.
Well, Lithium is also a very reactive metal too. Which means it has lots of energy stored up in it that can be tapped to do useful things, like being a battery electrode. Lithium Ion batteries exploit this physical trait to give us the highest energy density batteries on the market save for some exotic specialty chemistries, like Zinc Air. Lithium Ion uses all kinds of tricks to keep the water and moisture out of the mix inside the battery. However these tricks take away from the total energy density of the battery. So now the race is on to use pure metallic lithium in a battery without having to use any tricks to protect it from water.
A company based in Berkeley, CA, is developing lightweight, high-energy batteries that can use the surrounding air as a cathode. PolyPlus is partnering with a manufacturing firm to develop single-use lithium metal-air batteries for the government, and it expects these batteries to be on the market within a few years. The company also has rechargeable lithium metal-air batteries in the early stages of development that could eventually power electric vehicles that can go for longer in between charges.