A Quad Battery Phone Technology or Wireless Charge? Can we Innovate --Futuristics

There are dual SIM phones but no dual battery phones. I mean if we miniaturise the phone batt., we can have 4 batteries in one phone

WE can charge the batteries in the docket or in phone and switch to various batteries when need arises.
Surely some engineering at this front can make consumers life easy.
Or going to the futuristics if there is some way to wirelessly charge the phone, just like we get the audio signal if we can charge the phone vi aa WAN then life could be even easier and we could do without miniaturisation with a single battery.