Abstract: A method is provided for synthesizing a metal-doped transition metal hexacyanoferrate (TMHCF) battery electrode. The method prepares a first solution of AxFe(CN)6 and Fe(CN)6, where A cations may be alkali or alkaline-earth cations. The method adds the first solution to a second solution containing M-ions and M?-ions. M is a transition metal, and M? is a metal dopant. Subsequent to stirring, the mixture is precipitated to form AxMcM?dFez(CN)n.mH2O particles. The AxMcM?dFez(CN)n.mH2O particles have a framework and interstitial spaces in the framework, where M and M? occupy positions in the framework. Alternatively, the method prepares AaA?bMyFez(CN)n.mH2O particles. A and A? occupy interstitial spaces in the AaA?bMyFez(CN)n.mH2O particle framework. A metal-doped TMHCF electrode is also provided.

Abstract: A battery structure is provided for making alkali ion and alkaline-earth ion batteries. The battery has a hexacyanometallate cathode, a non-metal anode, and non-aqueous electrolyte. A method is provided for forming the hexacyanometallate battery cathode and non-metal battery anode prior to the battery assembly. The cathode includes hexacyanometallate particles overlying a current collector. The hexacyanometallate particles have the chemical formula A?n, AmM1xM2y(CN)6, and have a Prussian Blue hexacyanometallate crystal structure.

Abstract: A structure of intimately contacting carbon-hexacyanometallate is provided for forming a metal-ion battery electrode. Several methods are provided for forming the carbon-hexacyanometallate intimate contact. These methods include (1) adding conducting carbon during the synthesis of hexacyanometallate and forming the carbon-hexacyanometallate powder prior to forming the paste for electrode printing; (2) coating with conducting carbon after hexacyanometallate powder formation and prior to forming the paste for electrode printing; and (3) coating a layer of conducting carbon over the hexacyanometallate electrode.

Abstract: A supercapacitor is provided with a method for fabricating the supercapacitor. The method provides dried hexacyanometallate particles having a chemical formula AmM1xM2y(CN)6.pH2O with a Prussian Blue hexacyanometallate, crystal structure, where A is an alkali or alkaline-earth cation, and M1 and M2 are metals with 2+ or 3+ valance positions. The variable m is in the range of 0.5 to 2, x is in the range of 0.5 to 1.5, y is in the range of 0.5 to 1.5, and p is in the range of 0 to 6. The hexacyanometallate particles are mixed with a binder and electronic conductor powder, to form a cathode comprising AmM1xM2y(CN)6.pH2O. The method also forms an activated carbon anode and a membrane separating the cathode from the anode, permeable to A and A? cations. Finally, an electrolyte is added with a metal salt including A? cations. The electrolyte may be aqueous.

Abstract: A transition metal hexacyanoferrate (TMH) cathode battery is provided. The battery has a AxMn[Fe(CN)6]y.zH2O cathode, where the A cations are either alkali or alkaline-earth cations, such as sodium or potassium, where x is in the range of 1 to 2, where y is in the range of 0.5 to 1, and where z is in the range of 0 to 3.5. The AxMn[Fe(CN)6]y.zH2O has a rhombohedral crystal structure with Mn2+/3+ and Fe2+3+ having the same reduction/oxidation potential. The battery also has an electrolyte, and anode made of an A metal, an A composite, or a material that can host A atoms. The battery has a single plateau charging curve, where a single plateau charging curve is defined as a constant charging voltage slope between 15% and 85% battery charge capacity. Fabrication methods are also provided.

Abstract: A method is provided for forming a metal-ion battery electrode with large interstitial spacing. A working electrode with hexacyanometallate particles overlies a current collector. The hexacyanometallate particles have a chemical formula AmM1xM2y(CN)6·zH2O, and have a Prussian Blue hexacyanometallate crystal structure, where A is either alkali or alkaline-earth cations. M1 and M2 are metals with 2+ or 3+ valance positions. The working electrode is soaked in an organic first electrolyte including a salt including alkali or alkaline earth cations. A first electric field is created in the first electrolyte between the working electrode and a first counter electrode, causing A cations and water molecules to he simultaneously removed from interstitial spaces in the Prussian Blue hexacyanometallate crystal structure, forming hexacyanometallate particles having the chemical formula of Am?mM1xM2y(CN)6·z?H2O, where m?<m and z?<z, overlying the working electrode.

Abstract: A protected transition metal hexacyanoferrate (TMHCF) battery cathode is presented, made from AxMyFez(CN)n.mH2O particles, where the A cations are either alkali or alkaline-earth cations, and M is a transition metal. In one aspect the cathode passivation layer may be materials such as oxides, simple salts, carbonaceous materials, or polymers that form a film overlying the AxMyFez(CN)n.mH2O particles. In another aspect, the cathode passivation layer is a material such as oxygen, nitrogen, sulfur, fluorine, chlorine, or iodine that interacts with the AxMyFez(CN)n.mH2O particles, to cure defects in the AxMyFez(CN)n.mH2O crystal lattice structure. Also presented are TMHCF battery synthesis methods.