Disclosed is an air cell with higher energy density than before. An air cell comprises an electrolyte solution containing a potassium hydroxide solution having a pH of 17.3 or more under a temperature condition of 23 C., an anode containing iron, and a cathode.

Provided is a NiFe battery comprising an iron electrode which is preconditioned prior to any charge-discharge cycle. The preconditioned iron electrode used in the NiFe battery is prepared by first fabricating an electrode comprising an iron active material, and then treating the surface of the electrode with an oxidant to thereby create an oxidized surface.

Provided is a process for preparing an electrode comprising an iron active material. The process comprises first fabricating an electrode comprising an iron active material, and then treating the electrode with a gaseous oxidant to thereby create an oxidized surface. The resulting iron electrode is preconditioned prior to any charge-discharge cycle to have the assessable surface of the iron active material in the same oxidation state as in discharged iron negative electrodes active material.

Provided is a process for preparing an electrode comprising an iron active material. The process comprises first fabricating an electrode comprising an iron active material, and then treating the surface of the electrode with an oxidant to thereby create an oxidized surface. The resulting iron electrode is preconditioned prior to any charge-discharge cycle to have the assessable surface of the iron active material in the same oxidation state as in discharged iron negative electrodes active material.

The present invention provides one with a NiFe battery exhibiting enhanced power characteristics. The battery uses a particular electrolyte comprising sodium hydroxide, lithium hydroxide, and sulfide. The use of the sodium hydroxide based electrolyte with the iron anode in the battery has been found to enhance the performance characteristics of the battery. The resulting characteristics of specific power and power density are much improved over conventional NiFe batteries.

The invention provides a method of storing varying or intermittent electrical energy and one or more of hydrogen (H.sub.2) and oxygen (O.sub.2) with an energy apparatus, the method comprising: providing the first cell aqueous liquid, the second cell aqueous liquid, and electrical power from an external power source to the functional unit thereby providing an electrically charged functional battery unit and one or more of hydrogen (H.sub.2) and oxygen (O.sub.2) stored in said storage system, wherein during at least part of a charging time the functional unit is charged at a potential difference between the first cell electrode and the second cell electrode of more than 1.37 V.

Systems and methods of the various embodiments may provide a battery including a rolling diaphragm configured to move to accommodate an internal volume change of one or more components of the battery. Systems and methods of the various embodiments may provide a battery housing including a rolling diaphragm seal disposed between an interior volume of the battery and an electrode assembly within the battery. Various embodiments may provide an air electrode assembly including an air electrode supported on a buoyant platform such that the air electrode is above a surface of a volume of electrolyte when the buoyant platform is floating in the electrolyte.

A secondary electrochemical cell includes a negative electrode including as an output conductor, a metallic or metal-coated open-pore form or a metallic or metal-coated nonwoven, as a carbon-based storage material that enables storage of electrical charge in the electrode through formation of an electrical double layer (Helmholtz double layer), activated carbon having a BET surface area of at least 800 m.sup.2/g, a non-carbon-based H2 storage material that can chemisorb hydrogen and/or store it as a metal hydride, a positive electrode including as an output conductor, a metallic or metal-coated open-pore form or a metallic or metal-coated nonwoven, and nickel hydroxide and/or nickel oxyhydroxide, a porous separator that separates the negative electrode and the positive electrode from one another, an aqueous alkaline electrolyte with which the electrodes and the separator are soaked, and a housing that encases the electrodes, the separator and the electrolyte.

An energy apparatus comprising at least one functional unit including a first cell comprising a first cell electrode and at least one first cell opening for a first cell aqueous liquid and for a first cell gas. The first cell electrode comprises an iron-based electrode; a second cell comprising a second cell electrode and at least one second cell opening for a second cell aqueous liquid and for a second cell gas. The second cell electrode comprises at least one metal comprising 60-99.9 at. % nickel, and 0.1-35 at. % iron and a separator. The first cell and the second cell share the separator which is configured to block transport of at least one of O2 and H2 from one cell to another while having permeability for at least one of hydroxide ions (OH?) monovalent sodium (Na+), monovalent lithium (Li+) and monovalent potassium (K+).

According to one aspect, an additive for an iron negative electrode of an alkaline electrochemical cell may include a powder of discrete granules including agglomerated particles, the agglomerated particles including at least one metal sulfide.