The issue you have isn't with Li-ion -- it has one of the best volumetric energy densities of all commercially available technologies today. [0] Even experiment

The issue you have isn't with Li-ion -- it has one of the best volumetric energy densities of all commercially available technologies today. [0] Even experimental technologies don't promise more than 2x. No, your issue isn't with Li-ion, your issue is with physics. As long as power draw stays within an order of magnitude of current mobile devices (note: backlights and radios put a hard lower-bound on this, and devices are already approaching it asymptotically) your dream is not possible without some different technology altogether. One of those different technologies might be remote wireless charging. [0]: https://upload.wikimedia.org/wikipedia/commons/c/c9/Secondary_cell_energy_density.svg https://upload.wikimedia.org/wikipedia/commons/c/c9/Secondar...