Batteries, just like many other technologies, are shrinking in size while holding a greater charge than its bulkier predecessors, because of the capabilities of Lithium-Ion batteries. This same trend is continuing with the newest technology, Aluminum- Ion batteries. According to a study done by Stanford scientists, Aluminum-Ion batteries charge much faster, and hold a much greater charge than Lithium-Ion batteries, but they only produce an output of 2 V with a weak energy density, so scientists will have to improve upon that before the technology may become mass produced. Another cool property of Aluminum-Ion batteries is that even after thousand of charges there was no capacity decay, and with Lithium Ion batteries their capacity almost fully decays after a few hundred charges. This new technology, in my opinion, is going to revolutionize the future of our technology.
Here is the link to the study done by Stanford.