I recently learned about an activity at CERN. They try to transport antiprotons to a different site for better analysis. "BASE STEP" https://home.cern/news/news/experiments/base-experiment-take...

Surprisingly, antimatter can be stored for months. They built a 2.5 ton storage box, ultra high vacuum and magnetic trap and a loading mechanism. In a first trial they loaded 70 protons and drove around the campus on a truck.

Impressive that this is even possible. But with 2.56 * 10^-15 Wh/kg still orders of magnitude from current batteries.