This method achieves lithium cobalt pyrophosphate in which the generation of different phases is suppressed. A powder of a lithium compound, a cobalt compound and a phosphorus compound in amounts based on the composition of lithium cobalt pyrophosphate is mixed while adding water at a prescribed temperature (T1), for example, room temperature, and the substance obtained thereby is further mixed at a higher temperature (T2), for example, 40° C.-60° C. In this way, a precursor of lithium cobalt pyrophosphate is formed that has excellent uniformity of distribution of the lithium component, the cobalt component and the phosphorus component. By firing such a precursor, a lithium cobalt pyrophosphate is obtained in which the generation of different phases is suppressed.

A positive electrode (21) includes a positive electrode current collector (21A), and a positive electrode mixture layer (21B) which is formed on the positive electrode current collector (21A) and contains a positive electrode active material. The positive electrode mixture layer (21B) includes a first positive electrode active material (21B-1) composed of LiVPO.sub.4F and a second positive electrode active material (21B-2) composed of LiVP.sub.2O.sub.7. In addition, a mixing ratio of the first positive electrode active material (21B-1) and the second positive electrode active material (21B-2) contained in the positive electrode mixture layer (21B) is represented by (1−x)LiVPO.sub.4F+xLiVP.sub.2O.sub.7 (x is a mass ratio, 0<x≤0.21).

A positive electrode material for a secondary battery, wherein the positive electrode material includes a triclinic crystal structure.

A positive electrode material for a secondary battery, wherein the positive electrode material includes a triclinic crystal structure.

A material, especially a glassy material of pyrophosphate type, corresponding to the general formula (I): {[(M.sup.2+).sub.1−x(R.sup.+).sub.2x].sub.2[(P.sub.2O.sub.7.sup.4−).sub.1−y(PO.sub.4.sup.3−).sub.4y/3]} n(H.sub.2O) in which x and y are positive rational numbers each between 0 and 0.8, and n is such that the weight percentage of water in the material is greater than 0 and less than or equal to 95. M.sup.2+ represents a bivalent ion of a metal chosen from calcium, magnesium, strontium, copper, zinc, cobalt, manganese and nickel, or any mixture of such bivalent ions. R.sup.+ represents a monovalent ion of a metal selected from potassium, lithium, sodium, and silver, or any mixture of such monovalent ions. This material in particular can be used in manufacturing of bone replacements or prosthesis coatings.

A positive electrode plate may comprise a positive electrode current collector and positive electrode film layers having a single-layer or multi-layer structure provided on at least one surface of the positive electrode current collector; when the positive electrode film layers have a single-layer structure, at least one of the positive electrode film layers may comprise a first positive electrode active material and a second positive electrode active material selected from LiFePO.sub.4, carbon-coated LiFePO.sub.4, LiFe.sub.bD.sub.cPO.sub.4 and carbon-coated LiFe.sub.bDc.sub.PO.sub.4; and/or when the positive electrode film layers have a multi-layer structure, at least one layer of the at least one of the positive electrode film layers may comprise the first and second positive electrode active materials; and the first positive electrode active material may comprise an inner core containing Li.sub.1+xMn.sub.1-yAyP.sub.1-zR.sub.zO.sub.4, a first coating layer containing pyrophosphate and phosphate, and a second coating layer containing a carbon element.

Polyphosphate compositions are produced by a process that includes the steps of continuously introducing a phosphate compound into a polymerization vessel, polymerizing the phosphate compound at a temperature of 250-450° C. for a time period sufficient to form the polyphosphate composition, and continuously discharging the polyphosphate composition from the polymerization vessel. The phosphate compound can be fed to the polymerization vessel in the form of an aqueous slurry containing 5-50 wt. % of the phosphate compound. Resulting polyphosphate compositions often contain at least 8 wt. % of a polyphosphate and less than 35 wt. % of the phosphate compound.

Techniques are described for preparing a water filtration composition that includes activated carbon having an ash content of at least 10 wt. % and particles of a solubilizing agent. The solubilizing agent forms a water-soluble complex with cations (e.g., calcium ions). This increases the solubility of calcium ions and other scale-forming ions in water, thus suppressing scale formation on interior surfaces of water processing infrastructure. The activated carbon and the solubilizing agent are processed to have particle sizes in a same range, thus enabling the activated carbon and the solubilizing agent to be thoroughly mixed together.

Techniques are described for preparing a water filtration composition that includes activated carbon having an ash content of at least 10 wt. % and particles of a solubilizing agent. The solubilizing agent forms a water-soluble complex with cations (e.g., calcium ions). This increases the solubility of calcium ions and other scale-forming ions in water, thus suppressing scale formation on interior surfaces of water processing infrastructure. The activated carbon and the solubilizing agent are processed to have particle sizes in a same range, thus enabling the activated carbon and the solubilizing agent to be thoroughly mixed together.

The present invention relates to a positive electrode active material for a potassium secondary battery, the positive electrode active material according to the present invention is a crystalline material comprising: K; a transition metal; P; and O, and comprises, as a main image, an image indicating a diffraction peak having a relative intensity of 5% or more in a range of Bragg angles (2θ) of a X-ray diffraction pattern of 14.7° to 15.7°, 22.1° to 23.1°, 25.5° to 26.5°, and 29.7° to 30.8°, when the relative intensity of the diffraction peak having the highest intensity is taken as 100% in the powder X-ray diffraction pattern of the material.