Lithium-ion batteries gave birth to the laptop and phone revolutions of the past decade and are now bearing down on motor vehicles and our electric power infrastructure and business models like an avalanche boiling down-slope on the trees below. This avalanche's trigger was John Goodenough who invented the lithium-cobalt-oxide cathode and made lithium-ion batteries a reality. Since then, folks like Jeff Dahn have been steadily refining battery structure and the electrolyte’s secret-sauce, but the fundamentals of LCO cathode (and variants on it) plus graphite anode have remained the best we can do. The graphite anode is bulky, and far from what we know to be possible; ideally we would use pure lithium, reducing this extra bulk and increasing the stored energy two fold. So far no one has successfully commercialized such an anode.
SolidEnergySystems.com now claims that they have developed a working lithium anode strategy and that it will be seen in upcoming tech products soon. The battery business is full of promising announcements, most of which seem to vanish and there are plenty of remaining questions for SolidEnergy including cycle life and power density. Is SolidEnergy different? I don't know, but they seem pretty far along, and say their batteries will be in "watches and wearables" this year. Apple is expected to have their annual fall product announcement the first week of September: it would be fun if one of their new features is doubled-battery life.