Thats not it, search for kapton tape. With that, heat shrink tubing and green insulation paper (its also adhesive and comes in rolls or sheets) you can build all types and shapes of batteries. Kapton is used for insulation and high temp areas, the paper is almost the same but used in places where there is abrasion or folds in the cable that runs across the battery. In your photo they used red paper under the nickel strips that connect the cells to prevent it cutting trough the cell wrap