Provided is a material that can be used as a potassium secondary battery positive electrode active material (particularly a potassium ion secondary battery positive electrode active material), other than Prussian blue, by using a potassium compound and a potassium ion secondary battery positive electrode active material comprising the potassium compound, the potassium compound being represented by general formula (1):
K.sub.nA.sub.kBO.sub.m,
wherein A is a positive divalent element in groups 7 to 11 of the periodic table; B is positive tetravalent silicon, germanium, titanium or manganese, excluding a case in which A is manganese and B is titanium, and a case in which A is cobalt and B is silicon; n is 1.5 to 2.5; and m is 3.5 to 4.5.

Provided are a spinel-type lithium manganese oxide excellent in terms of charge-discharge performance at high temperatures and a lithium secondary battery excellent in terms of charge-discharge performance at high temperatures. A spinel-type lithium manganese oxide comprising a phosphate, the spinel-type lithium manganese oxide being represented by chemical formula: Li.sub.1+xMn.sub.2XYM.sub.YO.sub.4 (where 0.02X0.20, 0.05Y0.30, and M represents Al or Mg), wherein the phosphate has an average particle size of 0.1 m or more and 2.0 m or less, and primary particles of the spinel-type lithium manganese oxide have an average size of 1.5 m or more and 5.0 m or less, a method for producing the spinel-type lithium manganese oxide, and applications of the spinel-type lithium manganese oxide.

High-temperature thermochemical energy storage materials using doped magnesium-transition metal spinel oxides are provided. transition metal spinel oxides, such as magnesium manganese oxide (MgMn).sub.3O.sub.4, are promising candidates for high-temperature thermochemical energy storage applications. However, the use of these materials has been constrained by the limited extent of their endothermic reaction. Embodiments described herein provide for doping magnesium-transition metal spinel oxides to produce a material of low material costs and with high energy densities, creating an avenue for plausibly sized modules with high energy storing capacities.

A compound M.sub.jX.sub.p which is particularly suitable for use in a battery prepared by the complexometric precursor formulation methodology wherein: M.sub.j is at least one positive ion selected from the group consisting of alkali metals, alkaline earth metals and transition metals and j is an integer representing the moles of said positive ion per moles of said M.sub.jX.sub.p; and X.sub.p, a negative anion or polyanion from Groups IIIA, IVA, VA, VIA and VIIA and may be one or more anion or polyanion and p is an integer representing the moles of said negative ion per moles of said M.sub.jX.sub.p.

A battery includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode includes Li.sub.xAl.sub.2(OH).sub.7-y.zH.sub.2O where 0.9<x<1.1, 0.1<y<0.1, 0z<2.1.

A method for preparing a zinc manganate anode material is disclosed. The method includes the following steps: (1) preparing a solution A containing a manganese ion and a solution B containing zinc alkali; (2) dispersing an adsorption carrier into the solution B; (3) using an alkali solution as a base solution and adding the solution A, the solution B and an oxidant solution to the base solution while stirring; (4) conducting a solid-liquid separation of the materials after reaction to obtain a solid; and (5) washing, drying and calcining the solid to obtain a zinc manganate anode material.

Provided is a material that can be used as a potassium secondary battery positive electrode active material (particularly a potassium ion secondary battery positive electrode active material), other than Prussian blue, by using a potassium compound and a potassium ion secondary battery positive electrode active material comprising the potassium compound, the potassium compound being represented by general formula (1):

K.sub.nA.sub.kBO.sub.m,

wherein A is a positive divalent element in groups 7 to 11 of the periodic table; B is positive tetravalent silicon, germanium, titanium or manganese, excluding a case in which A is manganese and B is titanium, and a case in which A is cobalt and B is silicon; n is 1.5 to 2.5; and m is 3.5 to 4.5.

Particulate LMFP cathode materials having high manganese contents and small amounts of dopant metals are disclosed. These cathode materials are made by milling a mixture of precursor materials in a wet or dry milling process. Preferably, off-stoichiometric amounts of starting materials are used to make the cathode materials. Unlike other high manganese LMFP materials, these cathode materials provide high specific capacities, very good cycle life and high energies even at high discharge rates.

A method of producing submicrometer- to micrometer-sized spherical particles, the method comprising dissolving a lithium salt and a metal salt in water or alcohol forming a precursor solution, spraying the precursor solution to form fine aerosolized droplets, flowing the aerosolized droplets into a pyro lysis flame producing submicrometer- to micrometer-sized spherical particles. The submicrometer- to micrometer-sized spherical lithium-metal oxide powders produced are cathode materials for Li-ion batteries.

The present invention relates to a method of producing metal nanoparticles and metal sulfide nanoparticles using a recombinant microorganism co-expressing metallothionein and phytochelatin synthase, which are heavy metal-adsorbing proteins, and to the use of metal nanoparticles and metal sulfide nanoparticles synthesized by the method. The present invention provides a method for synthesizing metal nanoparticles which have been difficult to synthesize by conventional biological methods. The present invention makes it possible to synthesize metal nanoparticles in an environmentally friendly and cost-effective manner, and also makes it possible to synthesize metal sulfide nanoparticles. In addition, even metal nanoparticles which could have been produced by conventional chemical or biological methods are produced in a significantly increased yield by use of the method of the present invention.