Tesla's battery technology arguably represents a paradigm shift in how batteries work. At least, they reportedly re-envisioned it from first principles. Tesla has chosen to keep this technology proprietary and make lots of money off of it rather than publish it, but it's not unlikely that it represents some serious original research.

How much of that is done by Musk himself is debatable. One of my pet peeves about the Musk fan-club is that he tends to partner with some very brilliant engineers and then get all the credit for the work they do. However, people high up in his companies (more than one of them) have said that he involves himself very extensively in discovering the technology itself, and his bachelors and the first couple years of his Ph.D were both in physics, so it seems likely that he does at least know the science behind what his companies do.