Google Gets into Battery Arms Race
wsj.com
wsj.com
It looks to me like they're probably dumping ~$3 million/year into a battery lab, which gives them state-of-the-art testing facilities and in-house expertise, and thus the ability to knowledgeably stay on top of what's going on in the battery space, what's real and what's not, and the strengths and weaknesses of different technologies.
The probability that Google will invent something important is low, but the business value of having a battery group justifies the cost, given the importance of batteries in portable devices, electric cars, solar energy storage, etc.
Of course, if you're talking about scifi theoreticals, the thing to do would be to calculate the energy from mixing X/2 volume of matter with X/2 volume of antimatter (presumably with some amount of the total volume skimmed off the top for containment structure).
Small black holes decay very quickly, a black hole the mass of, let's say a small mountain, would decay almost immediately, releasing it's energy as hard gamma via hawking radiation, whose energy could be captured and used via multiple processes including some sort of sterling engine/photovoltaic mechanism.
If some how you were able to create a small "artificial black hole" you could just feed it mass, any mass, and it would be converted directly in energy, as if it were a matter/anti-matter reaction.
At least, that's what my two semesters of modern physics and latent desire to be eventually be a sci fi author tell me. I am reasonably sure nature has some sort of small print that kills my awesome idea, like requiring 100x to create said black hole than energy released, bleh nature. IANAP.
http://en.memory-alpha.org/wiki/Artificial_quantum_singulari...
Start off with e=mc^2, revise downward with appropriate number of engineering constraints.
I'd imagine in practice that gets limited mostly by battery chemistry. So something like total reaction energy of components * conversion efficiency - conversion machinery mass - packaging / safety mass.
Which, afaict, is why "battery breakthroughs" all tend to be in the chemistry or conversion efficiency.
While pretty much everything above is related to chemistry/conversion efficiency, I was just trying to define the efforts a bit more along the goals.
Chemically, seems XeF2 has the upper bound on energy density, but I can't find the energy per volume (which, from molecular structure, looks astoundingly high). ...not that you want pure Fluorine as exhaust...
http://en.wikipedia.org/wiki/Energy_density
By unit mass, lithium ion batteries have about 1/50th the energy of gasoline.
While volume isn't mentioned in the link, I'm surprised that supercapacitors fare so poorly per weight.
I doubt Apple, Tesla or other heavily battery-tech-dependent companies would allow their staff to even hint about this kind of research.