In 2022, I wrote a post arguing that batteries would be the defining technology of the 2020s. That was just a few months before the release of ChatGPT and the boom in generative AI. In light of that sudden efflorescence, the humble battery might seem quaint and prosaic, and my post might seem laughably mistimed. And yet two years later, I think my post still holds up. These two years have seen small battery-powered drones utterly change the way wars are fought. They have seen battery storage bec...