Battery technology has been a big constraint on portable devices for many years, and though there have been improvements, they are all incremental, with serious portable power still weighing in heavily. I used to use a tablet laptop which would last all day on battery, but only by having an add-on battery as well, and it did make it quite a weight to lug about.
Toshiba have come up with a production version of a much better battery – see here. Based on Lithium Ion technology, but capable of 90% recharge in 5 minutes. That feels short enough to make a major difference to portable devices, as well as to Electric Vehicles. For example, how about a recharge whilst you shop?