Silver mediation of Fe(VI) charge transfer:: Activation of the K2FeO4 super-iron cathode

An unexpectedly large Ag(II) mediation of Fe(VI) redox chemistry improves alkaline Fe(VI) cathodic charge transfer. Combined with a Zn anode, this results in a cell with 3- to 5-fold higher energy capacity than the conventional high-power Zn/MnO2 alkaline battery, and tA ice that previously observed for Zn/BaFeO4. Both experimental results and a model of this phenomenon are presented. The Ag(II) salt may be introduced as a simple composite of AgO with the Fe(VI) salt. The Fe(VI) super-iron salt K2FeO4 has a high 3e(-) intrinsic charge capacity (406 mA/g), and is more environmentally benign than the Fe(VI) salt BaFeO4, but had exhibited comparatively poor charge transfer. Successful AgO cathodic activation of both K2FeO4 and BaFeO4 redox chemistry are presented. Various other K2FeO4 activators are also studied. An observed interaction of Fe(VI) with Mn(VII/VI) can improve charge efficiency of a K2FeO4 composite with KMnO4 or BaMnO4, albeit not to the extent observed in an K2FeO4/AgO composite cathode. The extent of an activation effect of oxides, hydroxides, and titanates salts, as well as KMnO4, BaMnO4. AgMnO4, and fluorinated graphites, on the cathodic discharge of K2FeO4 are probed.