As hydrocarbons are a difficult enemy to tame, the most relevant path is the one that leads to great energy per unit of mass. Lithium-ion technology could be improved making modifications in the anode, but at the same time this increases the potential risk. It's well-known that lithium-ion batteries should be treated with care because their tendency to explode and catch fire in some circumstances.
Some researchers were trying to solve this issue using a solid electrolyte instead of a liquid one. Although the achieved watts-hour per kilogram was not comparable until the idea of using an especially designed solid cathode based in non expensive chemistry.
It looks like the goal of the research was to produce an advance, but without making trips to the moon, thus keeping the costs low and ready for a developing EV industry, with a big market and amazing possibilities to solve the environmental disaster created by combustion engines.
The company that has the gift in their hand is from US, with "A specific energy (Wh/kg) that is nearly 3-times greater than current Li-ion batteries". It was even awarded with a grand by the big player DARPA.
If the usual range for affordable electric cars is 150-250 km, it would be near 500 km easily and low-cost, without accounting luxury as it should in these circumstances of air toxicity.
We hope that they are also working to create a standard model of battery for any EV, technology independent so making fast-swap and long distance traveling a piece of cake, and favoring more competition and development to the market.