Not real. Yet.

Stanford creates everlasting battery electrode & free, water-based electrolyte | ExtremeTech: ow, batteries are already extensively used in the power grid to even out the peaks and troughs of generation and consumption — but such batteries are incredibly expensive, must be regularly maintained, and have very short lifespans. Stanford, however, has developed a new battery electrode that can survive 40,000 charge/discharge cycles — enough for 30 years of use on the grid. Its ruggedness and longevity is a virtue of the material being used: copper hexacyanoferrate.