Ironically, today's most fashionable battery material, lithium, is the third-lightest element in that table and therefore one for which no such relativistic effects can be expected.

ECONOMIST: Einstein and car batteries

Parekh and Perry declined to describe what changes they have made to the stack, other than to say they are drastically reducing the amount of material needed to store power, and that their concept can be applied to any number of different battery chemistries.

FORBES

But for the process to result in a working battery, all five layers must stick together and work in synchrony, and the tricky step was finding a separator material that kept the whole stack in one piece.

BBC: 'Paint-on' batteries demonstrated