No, if you go and chase down the original article the electrolyte is NOT unknown, but an anhydrous aluminium chloride/organic chemical. The cells the researchers are producing are putting out around 1.9 to 2 volts, and the cells are resilient over at least 7500 charge/discharge cycles. The cathode is graphite foam built on a nickel foam substrate, the anode is aluminium foil.
To be honest, the only real kicker about the entire battery is the fact that water in the electrolyte severely reduces the performance, but this could at least be mitigated in production by adding in a water absorbing chemical of some sort to the system. Apart from that it all seems very promising indeed, and as aluminium and carbon are both extremely common (as opposed to lithium, where the resources are limited) then commercialising this battery would seem to be an eminently sensible thing to do.
The basic problem with power we have at the moment is not that we don't have enough, but that all the easy sources are diffuse and low density, or are bursty in nature. Solar cells, for instance, produce no power at night. Tidal generators also produce power only at set though predictable times. We already have good storage batteries, but the problem with them is that they are expensive.
These cells have the potential (*ahem*) to be cheap. Cheap power storage solves a very great many problems, since we can then concentrate on developing cheap, efficient and durable solar cells knowing that there will be a market for the power and that this power can then be stored efficiently; if you lack power storage, then the effective momentary market price of solar electricity drops to almost nothing when the sun shines, and rises astronomically as the sun sets.