The present invention provides a cost-effective method of synthesizing phosphate salt of a metal such as Fe and Mn that can be used for electrode active material of a lithium secondary battery. A precipitation reaction is first carried out to produce a solid salt of the metal having a lower valence value, e.g. Fe(II) and Mn(II). The solid salt is then purified before it is oxidized to form the target phosphate salt of the metal having a higher valence value, e.g. Fe(III) and Mn(III). The invention exhibits numerous technical merits such as easier operation, higher purity, and less consumption of washing water, among others.

It is an object to provide a manufacturing method for a large amount of positive electrode active material with few variations, having a highly uniform surface condition, micro-size, and high performance. An aqueous solution of a compound, which becomes the source material for the positive electrode active material, is put in an airtight container and irradiated with microwaves, thus heating while water in the airtight container is evaporated and a high pressure is formed in the air tight container. A large amount of micro-sized positive electrode active material having a highly uniform surface condition can be formed. A compound, which becomes the source material for the positive electrode active material, is put in an airtight container and irradiated with microwaves, thus heating while water in the airtight container is evaporated and a high pressure is formed in the air tight container.

The present invention relates to a method of producing an iron containing compound, iron containing precursor, or iron containing aqueous solution comprising the steps of: providing direct reduced iron; dissolving the direct reduced iron in organic and/or inorganic acids to provide an iron containing aqueous solution, wherein insoluble impurities of the direct reduced iron are maintained in solid form throughout the dissolution process, to obtain an iron containing aqueous solution with suspended insoluble impurities; separating the said insoluble impurities from the iron containing aqueous solution obtaining a purified iron containing aqueous solution; and optionally solidifying said purified iron containing aqueous solution to provide the iron containing compound or iron containing precursor, by drying.

The present invention further relates to iron containing compounds, iron containing precursors, and iron containing aqueous solutions, and their use in battery components.

A method for producing a lithium iron phosphate precursor by using a retired lithium iron phosphate battery as a raw material is provided, which includes steps of: soaking a battery cell in acid, performing electrolysis to reclaim copper, oxidizing ferrous iron, precipitating iron phosphate, and precipitating lithium carbonate. After precipitation is completed, performing one-step reclaim to obtain the lithium iron phosphate precursor.

An energy storage composition can be used as a new Na-ion battery cathode material. The energy storage composition with an alluaudite phase of A.sub.xT.sub.y(PO4).sub.z, Na.sub.xT.sub.y(PO4).sub.z, Na.sub.1.702Fe.sub.3(PO4).sub.3 and Na.sub.0.872Fe.sub.3(PO4).sub.3, is described including the hydrothermal synthesis, crystal structure, and electrochemical properties. After ball milling and carbon coating, the compositions described herein demonstrate a reversible capacity, such as about 140.7 mAh/g. In addition these compositions exhibit good cycling performance (93% of the initial capacity is retained after 50 cycles) and excellent rate capability. These alluaudite compounds represent a new cathode material for large-scale battery applications that are earth-abundant and sustainable.

A process for enriching phosphorus and recovering vivianite by a biofilm method includes the following steps: 1) an aerobic phosphorus absorption stage; 2) an anaerobic phosphorus release stage; 3) a cyclic enrichment stage; 4) a seed crystal forming stage; and 5) a crystal forming stage. Phosphorus is enriched by the biofilm method and recovered with vivianite as a recovery product, which solves the problem of phosphorus removal from municipal sewage and improves the economic value; by preparing high dissolved oxygen at the aerobic stage, a high-concentration phosphorus recovery solution can be obtained with a relatively low carbon-phosphorus ratio and relatively high enrichment times, and the consumption of carbon sources can be reduced; since the oxidation-reduction potential is controlled to be less than −100 mv by the biofilm method at the anaerobic phosphorus release stage, the oxidation-reduction potential does not need to be adjusted again during the recovery of vivianite,

An LFP electrode material is provided which has improved impedance, power during cold cranking, rate capacity retention, charge transfer resistance over the current LFP based cathode materials. The electrode material comprises crystalline primary particles and secondary particles, where the primary particle is formed from a plate-shaped single-phase spheniscidite precursor and a lithium source. The LFP includes an LFP phase behavior where the LFP phase behavior includes an extended solid-solution range.

Disclosed are a preparation method and application of iron phosphate. The preparation method comprises: subjecting iron phosphate waste to calcination, dissolving it in an acid solution, and filtering to obtain filtrate, namely a solution A containing iron phosphorus; stirring a mixed solution of the solution A and a first alkali solution, adjusting pH of the mixed solution to acidity for reaction, and after washing and filtering to obtain second filter residue, namely an amorphous yellow iron phosphate filter cake; subjecting the yellow iron phosphate filter cake to aging and heating, adding phosphoric acid and a second alkali solution for reaction, followed by washing and filtering to obtain third filter residue, namely a basic ammonium iron phosphate filter cake, then drying to obtain basic ammonium iron phosphate crystal powder; and subjecting the basic ammonium iron phosphate crystal powder to calcination for dehydration and cooling to obtain iron phosphate.

A method for preparing a positive electrode active material is provided. The method for preparing a positive electrode active material may comprise the steps of: preparing a lithium precursor, an iron precursor, a phosphorus precursor, and abase solvent; mixing the base solvent and the lithium precursor to prepare a first source, mixing the base solvent and the iron precursor to prepare a second source, and mixing the base solvent and the phosphorus precursor to prepare a third source; and mixing the first source, the second source, the third source, and a chelating agent and allowing a reaction to occur in the mixture by a heat treatment method to prepare a positive electrode active material comprising a compound of lithium, iron, phosphorus, and oxygen.

Provided is a method for producing an intermediate product of an electrode. The method for producing an intermediate product of an electrode may comprise the steps of: preparing a base particle; forming a coating layer, comprising a first metal, on the surface of the base particle by mixing the base particle with a coating source which comprises the first metal; and forming a molten source, in which is melted a second metal and the base particle on which the coating layer is formed, by heat-treating the second metal and the base particle on which the coating layer is formed.