Israeli company Phinergy claim to have produced a battery that can power a Citroen C1 for 3000km, and have demonstrated a 1800km drive with a more practical version, three times that available from commercial electric cars. Even more dramatically, the battery weighs just 100km, a fifth of the weight of those in the Tesla Model S. Metal-air batteries use the oxygen in the air around them, rather than storing it in liquid or solid chemicals. They can store far more energy than most competing technologies. Not needing to contain the oxygen can also cut the weight dramatically – Phinergy claim...