I am not sure about that (biggest battery in the world). This looks like a battery "pack" (an array of batteries connected in parallel/series). This looks like just a marketing thing to me, because there is nothing new or special about it. Just "the biggest".

Germany is also working on big batteries for years, but with a completely different strategy. A redox-flow battery with polymers and saline solution (https://www.nature.com/articles/nature18909) Here is a recent german article about it (http://www.spiegel.de/wissenschaft/technik/brine4power-so-fu...)

This kind of batteries will hold 700 MWh.