The basic idea is that if you have more reactive materials in...

The basic idea is that if you have more reactive materials in the battery, the energy necessary to charge it will be higher... but in return, you get more energy back out. Fluorine is the strongest oxidising element we know (dioxygen difluoride, aka - most appropriately - "FOOF", is a stronger oxidiser, but frankly, you'd have to be crazy to work with that compound; "Things I Won't Work With" has more detail if you really want to know), so if you want to pack more energy in, it's a decent candidate for consideration.

That said, it looks like research into fluoride batteries is still at a relatively early stage, so I wouldn't be holding my breath on that possibility panning out in a hurry. It's more of a potential addition to the mine's prospects, given the fluorite mineralisation that has previously been disclosed - mineralisation that already holds potential commercial value, remember (although I don't think a JORC estimate has been formally released for it; they've only added barite to the resource estimates, if I remember rightly, so it's not something that can be properly quantified at this stage). Fluoride batteries are probably a minimum of five years, more likely ten years, from commercial production - if they can be commercially produced at scale - but they could displace quite a bit of lithium ion battery demand. Note all the "if"s and "could"s in this paragraph - this particular topic is still highly speculative.