Tesla Inc’s ( TSLA.O ) chief executive Elon Musk has suggested the U.S. electric carmaker may be able to mass-produce longer-life batteries with 50% more energy density in three to four years. “400 Wh/kg *with* high cycle life, produced in volume (not just a lab) is not far. Probably 3 to 4 years,” Musk tweeted on Monday ahead of its anticipated “Battery Day” event where Tesla is expected to reveal how it has improved its battery performance. Researchers have said the energy density of Panasonic’s ( 6752.T ) “2170” batteries used in Tesla’s Model 3 is around 260Wh/kg, meaning a 50% jump from the current energy density which is key to achieving a longer driving range. Tesla said its Battery Day will take place on the same day as its 2020 annual meeting of shareholders on Sept. 22. The electric car manufacturer also showed a […]