I have repaired the insulation on the metallic Eneloop cell case with Scotch tape (cellophane tape).
Another, in my opinion, much better, much stronger, with better insulating properties, and less prone to scuffing, would be Kapton tape. Also very thin, and used in automotive, aerospace, and general electronics industries for insulation, isolation, and protection.
Here is a random listing pulled from the web as an example:
The sellers spiel around the middle of the page provides info on the general qualities of the material. Plenty of resources online, but that page gives the gist of the material, and shows different sizes.
For additional excitement, look up Faraday Tape!
Kurt
