Regular lithium-ion batteries have electrodes arranged in multiple layers called a "jelly roll." By using different materials, 24M can build thicker electrodes and eliminate much of the manufacturing complexity. It also cuts down on the need for "filler" materials like plastics, copper and aluminum, reducing costs. The electrodes can also store more energy, making the entire battery more efficient.

24M is funded to the tune of the $7 million by the US Department of Energy, with the aim of developing cells with a 350 Wh/kg density by the end of 2019. It also supplied an industrial partner with batteries that achieved an energy density of 280 Wh/kg, and has seen up to 350 Wh/kg in the lab.

By contrast, Tesla's state-of-the-art 2170 Li-ion cells reportedly have energy densities up to around 257 Wh/kg. It recently announced the acquisition of Maxwell Technologies, which could help it significantly improve its current batteries. That deal is not yet closed, however, and Maxwell investors are reportedly suing to block it.

24M has touted manufacturing costs 40 percent lower than regular batteries. However, it has yet to reveal much about the battery chemistry and didn't say how many batteries it actually shipped -- and the landscape is littered with failed battery startups. Still, 24M's tech appears to be more than just a lab experiment and could boost battery technology in the near future. Plus, the green transportation industry needs all the tech it can get to meet its very ambitious goals.