Re: How many battery "breakthroughs" is that this year?
In my lifetime there have been thre general battery breakthroughs.
1/. Nickel cadmium. Developed in WWII this enabled secondary cells to rival primary cells for the first time. And made portable power tools possible, And indeed electric model aircraft.
2/. Nickel metal hydride. Not as robust as NiCd, but doubled energy /weight.
3/. Lithium Ion. At a stroke, yet more energy density. Making today's range of portable electronics and electrics all possible.
All of these are fundamentally about getting a chemistry that was known to work just about safe enough and stable enough to mass produce.
There is no better chemistry than lithium.
All the advances since are from fine tuning lithium chemistry, and this is another such fine tune.
There is probably one more technology to go - lithium air. Because it can utilise atmospheric oxygen, its about 3 times lighter than existing lithium (batteries), especially when charged. Back of envelope calculations show that a lithium air battery could, if it could be got to work, take an airliner across the Atlantic. With passengers. Just.
But as far as chemical batteries go, That's it. One might be better off making synthetic diesel from nuclear power stations derived electricity and running a conventional diesel or jet engine.