People are already familiar with wireless charging but Sony may be exploring newer kind of wireless charging between devices over NFC. Sony has recently filed a patent concerning the same.
Well in the patent it is not mentioned that the technology is particularly about the smartphones. The patent particularly discusses about the process of sharing power over hotspots. These hotspots can be from any device but Sony does not really go into the detail of how this technology works.
If we are transferring energy between two devices there is always going to be loss of energy. The amount of energy sent by one device will not be equal to the energy received, it is not going to be completely efficient.
But to clarify, Sony filing the patent does not mean that this feature will ever come to your smartphones. If Sony are able to implement this technology they must make it as efficient as possible, and even if it is integrated in smartphones, the person sharing their power won’t do it for long as battery life depletes fast enough in smartphones.