I'd like to know what are Lipo batteries and Lipo sacks. I also am assuming that a bunker is some sort of battery configuration in a box.
Lipo is a contration for Lithium Polymer batteries.
The simplest explanation would be to say that "LiPo" batteries are a second generation of Lithium Ion Batteries.
For a complete explanation you can check the listing in the Wikipedia Encyclopedia at;
A "battery bunker" is a reinforced, isolated, fireproof container for your batteries so in case they explode they won't burn down the whole house.