A primary battery including a positive electrode containing iron oxyhydroxide, a negative electrode containing magnesium or aluminum, and an electrolyte disposed between the positive electrode and the negative electrode.

In an embodiment, an active material-based nanocomposite is synthesized by infiltrating an active material precursor into pores of a nanoporous carbon, metal or metal oxide material, and then annealing to decompose the active material precursor into a first gaseous material and an active material and/or another active material precursor infiltrated inside the pores. The nanocomposite is then exposed to a gaseous material or a liquid material to at least partially convert the active material and/or the second active material precursor into active material particles that are infiltrated inside the pores and/or to infiltrate a secondary material into the pores. The nanocomposite is again annealed to remove volatile residues, to enhance electrical contact within the active material-based nanocomposite composite and/or to enhance one or more structural properties of the nanocomposite. In a further embodiment, the pores may be further infiltrated with a filler material and/or may be at least partially sealed.

An iron-zinc battery includes a positive electrode containing iron oxyhydroxide, a negative electrode containing zinc, and an aqueous electrolytic solution disposed between the positive electrode and the negative electrode. The aqueous electrolytic solution contains zinc chloride (ZnCl2), and the weight of the zinc chloride (ZnCl2) is equal to or more than the weight of water (H2O) contained in the aqueous electrolytic solution.

An iron-zinc battery includes a positive electrode containing iron oxyhydroxide, a negative electrode containing zinc, and an electrolyte disposed between the positive electrode and the negative electrode.

A novel aqueous battery configured to use sulfuric acid ions (SO.sub.4.sup.2−) as carrier ions. The aqueous battery is an aqueous battery comprising a cathode layer, an anode layer and an aqueous liquid electrolyte, wherein the cathode layer contains, as a cathode active material, a graphite; wherein the anode layer contains, as an anode active material, at least one selected from the group consisting of an elemental Zn, an elemental Cd, an elemental Fe, an elemental Sn, a Zn alloy, a Cd alloy, an Fe alloy, an Sn alloy, ZnSO.sub.4, CdSO.sub.4, FeSO.sub.4 and Sn.sub.5O.sub.4; wherein, as an electrolyte, at least one sulfate selected from the group consisting of ZnSO.sub.4, CdSO.sub.4, FeSO.sub.4 and Sn.sub.5O.sub.4 is dissolved in the aqueous liquid electrolyte; and wherein the aqueous liquid electrolyte has a pH of 3 or more and 14 or less.

Provided is an aqueous battery configured to use hydroxide ions (OH.sup.−) as carrier ions. The aqueous battery is an aqueous battery comprising a cathode layer, an anode layer and an aqueous liquid electrolyte, wherein the cathode layer contains, as a cathode active material, a graphite having a rhombohedral crystal structure; wherein the anode layer contains, as an anode active material, at least one selected from the group consisting of an elemental Zn, an elemental Cd, an elemental Fe, a Zn alloy, a Cd alloy, an Fe alloy, ZnO, Cd(OH).sub.2, Fe(OH).sub.2 and a hydrogen storage alloy; and wherein, as an electrolyte, at least one selected from the group consisting of KOH and NaOH is dissolved in the aqueous liquid electrolyte.

Methods and systems are provided for iron preformation in a redox flow battery. In one example, a method may include, in a first condition, discharging and then charging the redox flow battery, and in a second condition, charging the redox flow battery including preforming iron metal at a negative electrode of the redox flow battery, and thereafter entering an idle mode of the redox flow battery including adjusting one or more electrolyte conditions. In some examples, each of preforming the iron metal and adjusting the one or more electrolyte conditions may increase a battery charge capacity to greater than a threshold battery charge capacity.

A positive electrode for an alkaline secondary battery includes a positive electrode substrate and a positive electrode composite material that is provided on at least one surface of the positive electrode substrate. The positive electrode substrate contains a Ni foil or a Ni-plated steel foil. The positive electrode composite material contains a positive electrode active material. The positive electrode active material contains nickel hydroxide coated with cobalt oxyhydroxide. A weight per unit area of the positive electrode composite material with respect to the one surface of the positive electrode substrate is 0.02 g/cm.sup.2 to 0.035 g/cm.sup.2.

Materials, designs, and methods of fabrication for iron-manganese oxide electrochemical cells are disclosed. In various embodiments, the negative electrode is comprised of pelletized, briquetted, or pressed iron-bearing components, including metallic iron or iron-based compounds (oxides, hydroxides, sulfides, or combinations thereof), collectively called iron negative electrode. In various embodiments, the positive electrode is comprised of pelletized, briquetted, or pressed manganese-bearing components, including manganese (IV) oxide (MnO.sub.2), manganese (III) oxide (Mn.sub.2O.sub.3), manganese (III) oxyhydroxide (MnOOH), manganese (II) oxide (MnO), manganese (II) hydroxide (Mn(OH).sub.2), or combinations thereof, collectively called manganese oxide positive electrode. In various embodiments, electrolyte is comprised of aqueous alkali metal hydroxide including lithium hydroxide (LiOH), sodium hydroxide (NaOH), potassium hydroxide (KOH), cesium hydroxide (CsOH), or combinations thereof. In various embodiments, battery components are assembled in prismatic configuration or cylindrical configuration.

A secondary battery includes: a solid electrolyte layer including at least one of water (H.sub.2O) and a hydroxyl group (OH); a positive-electrode active material layer disposed on the solid electrolyte layer and including nickel hydroxide; a second electrode (positive electrode) disposed on the positive-electrode active material layer; a negative-electrode active material layer disposed on a lower surface of the solid electrolyte layer so as to be opposite to the positive-electrode active material layer, and including a titanium oxide compound (TiO.sub.x) including at least one of water and a hydroxyl group; a first electrode (negative electrode) disposed on a lower surface of the negative-electrode active material layer so as to be opposite to the second electrode; a p type semiconductor layer disposed between the positive-electrode active material layer and the second electrode; and an n type semiconductor layer disposed between the negative-electrode active material layer and the first electrode.