On Apr 8, 2015, at 6:36 AM, tomw via EV <ev@lists.evdl.org> wrote: > Nothing in his lab's list of peer-reviewed publications on this topic: > > http://dailab.stanford.edu/pubs.htm
My friend was able to get me a copy of the Nature article. The short version...is that I won't be replicating their work at home. However, I have a sneaking suspicion that it might be possible to make at home a battery that's not as good as what they made but still better than today's commercial batteries. I wouldn't bet more than a single beverage on that. My back-of-the-envelope guesstimate from the abstract yesterday suggested a C value of ~60. I wasn't far off: > Remarkably, the Al/graphitic-foam cell (in a pouch cell configuration) could > be charged and discharged at a current density up to 5,000 mA g21, about 75 > times higher (that is, at a 75 C rate, ,1 min charge/discharge time) than the > Al/PG cell while maintaining a similar voltage profile and discharge capacity > (,60 mA h g21) (Figs 1b and 2b). Another interesting tidbit: > It was also found that this cell could be rapidly charged (at 5,000 mA g21, > in ,1 min) and gradually discharged (down to 100 mA g21, Fig. 2d and Extended > Data Fig. 9b) over ,34 min while maintaining a high capacity (,60 mA h g21). The graphite foam was grown on a nickel foam scaffold. Making the electrolyte requires a vacuum oven and an argon-filled glove box. But, once you've got those ingredients (and some other stuff), "all" that's left: > Pouch cells were assembled in the glove box using a graphitic-foam (,3 mg) > cathode and an Al foil (,70 mg) anode, which were separated by two layers of > glass fibre filter paper to prevent shorting. Polymer (0.1 mm 3 4 mm 3 5 mm) > coated Ni foils (0.09 mm 3 3 mm 3 60 mm in size; MTI corporation) were used > as current collectors for both anode and cathode. The electrolyte (,2 ml > prepared using AlCl3/[EMIm]Cl 5 1.3 by mole) was injected and the cell was > closed using a heat sealer. My hope is that a less sophisticated carbon foam might suffice...which still leaves the question of the electrolyte. No clue on that front. The concluding paragraph explains where the confusion over the various density figures came from: > We have developed a new Al-ion battery using novel graphitic cathode > materials with a stable cycling life up to 7,500 charge/discharge cycles > without decay at ultrahigh current densities. The present Al/graphite battery > can afford an energy density of ,40 W h kg–1 (comparable to lead–acid and > Ni–MH batteries, with room for improvement by opti- mizing the graphitic > electrodes and by developing other novel cathode materials) and a high power > density, up to 3,000 W kg–1 (similar to super- capacitors). We note that the > energy/power densities were calculated on the basis of the measured ,65 mA h > g–1 cathode capacity and the mass of active materials in electrodes and > electrolyte. Such recharge- able Al ion batteries have the potential to be > cost effective and safe, and to have high power density. So, this would seem to be of most interest to the racing crowd and of less interest to for general automotive use, at least in this initial iteration. Mobile devices will probably hugely benefit, especially power tools. ...assuming, of course, that manufacturing isn't a problem, and all the rest of those sorts of "gotchas".... b& _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
