I was doing backscatter communications when I worked at Time Domain. The available power is quite limited (in contrast to the author's statement), and obviously depends on the size of the antenna. It doesn't take much energy to short-out and open an antenna, to provide the reflection, and this is what I believe they were trying to say. The strength of the reflecting signal depends on: antenna size (gain), distance, path loss (other scatter sources and blocking materials), and noise (jammers, etc). By the way, backscatter comms works with other radio signals that are available, as well.
Sometimes I have to resort to a Google search using the chemistry as keyword, to reveal the as-yet unknown supplier. Too often, I don't even have a part number, and so this helps with that too. Additionally, There are companies out there that can make a pack out of cells that you supply, or they buy for you and include in the pack cost.
Let's say I thought one of the exotic battery chemistries that you cover in this series was suitable for my application. How would I go about obtaining one (or in the case of a primary battery an ongoing supply)? Do you make it yourself or are some battery manufacturers happy to put together one for you?