AV1 is better than HEVC, is not patented, and was invented by companies interested in conserving bandwidth out of need. So yes, things get invented without patents.
Is it going to use more battery than HEVC? VP9 uses much more battery than H.264. Even when both have hardware decoders, VP9 uses a bit more juice. It's the computational complexity difference. Of course HEVC probably uses more juice than h.264 as well, but VP9 is notoriously inefficient and it would suck if AV1 was less energy efficient than HEVC.
Being royalty free does not mean it is not patented.