Fred, Don't you find it amusing that any in any new-but-old technology, the proponents try to diferentiate themselves on the slimest of variations.
The free market mantra seems to be, "If you cannot wow them with novelty, then confuse them with sublety". In the case of Evans, I'm not too sure how they are very different from any old electrolyitic capacitor, once you wade through the rhetoric. Here is the claim: The high capacitance of the Capattery results from an electrostatic charge stored at the interface between activated carbon and an aqueous electrolyte in the so-called electric double layer. "The Capattery improves upon previous double layer capacitors because of its patented Permselective valve, which allows the escape of CO2 generated by all double layer capacitors, while it maintains its sealed construction." OK, fine. But that is a minor (even trivial) improvement of an electolytic capacitor and not the chacteristic of a true bat-cap, which will also have a double layer but requires a solid electrolyte. This is a bit more than a fine distinction because solid electrolytes in the form of permeable and selective membranes are also the distinguishing characteristic between the FC (fuel cell) and the battery. IOW the FC is itself a type of battery (not just semantics), and indeed the very first really high powered battery, which we have alluded to before on vortex - the famous Grove cell - was more like a fuel cell than a battery. There is a great site online for the Grove battery, but I don't have it handy. IMHO the term: "bat-cap" if it is to have real meaning and not just be a marketing gimick - should be distinguished from the electrolytic capacitor by the necessity of a solid electrolyte plus a mobile postive-ion charge carrier. This confuses the situation since then (semanticly) there must be another electrolyte in the form of a "mobile" charge carrier, in addition to the membrane (which is often called: the "solid electroyte") in order to "feed" this third item - the solid electrolyte - and it should NOT be aqueous for the reason above. There are few good choices for the "mobile" charge carrier - the positive ion which can go though the solid electrolyte membrane ... and hydrogen, sodium, potassium and other alkali metals are really the only good choices. If it is hydrogen, you call it a fuel cell. Otherwise: To go 1) "gas-less" (no risk of explosion due to volatility) 2) cheap 3) available technology NOW - that leaves leavels only sodium. All of these details were recognized about 150 years ago, and just now are all the pieces coming together, and still ...so far as I know, there is no group or lab working on what should (in theory) be the "ideal" solution: which is something close to the sodium/solid electrolyte/activated-carbon-cap combination which I am calling the batt-cap (with the possible exception of EEStor, which has been "mum" about whatever else it is that they have added to the barium titanate based capacitor - but I have been assured that this product (EEStor) is not "just" a capacitor, nor an electroyltic capacitor, nor a fuel cell - so what does that leave? Are these fine distinction being too picky? Jones
