A positive electrode active material including a nickel-containing lithium transition metal oxide containing nickel in an amount of 60 mol % or more based on a total number of moles of transition metals excluding lithium, and a coating layer which is formed on a surface of the nickel-containing lithium transition metal oxide and includes a lithium-containing inorganic compound, a nickel oxide, and a nickel oxyhydroxide is provided. A method of preparing the positive electrode active material, and a positive electrode for a lithium secondary battery and a lithium secondary battery which include the positive electrode active material are also provided.

The invention provides a method for preparing lithium manganese iron phosphate, which includes the following steps: S1: mixing a manganese source and/or an iron source in solid phase to obtain a first mixture; S2: sintering the first mixture in solid phase at 300° C. to 1200° C. to obtain a manganese iron oxide (MnxFe1−x−y)mOn; S3: mixing the manganese iron oxide (MnxFe1−x−y)mOn with a lithium source, a phosphorus source, and optionally a manganese source and/or an iron source in solid phase to obtain a second mixture; and S4: sintering the second mixture in solid phase at 350° C. to 900° C. to obtain lithium manganese iron phosphate LiMnxFe1−x−yPO4, wherein 0≤x≤1, and 0≤y≤1. The method of the present invention can be used to prepare a lithium manganese iron phosphate material with high tap density, long cycle life, low costs, and high cost-effectiveness.

The invention provides a method for preparing lithium manganese iron phosphate, which includes the following steps: S1: mixing a manganese source and/or an iron source in solid phase to obtain a first mixture; S2: sintering the first mixture in solid phase at 300° C. to 1200° C. to obtain a manganese iron oxide (MnxFe1−x−y)mOn; S3: mixing the manganese iron oxide (MnxFe1−x−y)mOn with a lithium source, a phosphorus source, and optionally a manganese source and/or an iron source in solid phase to obtain a second mixture; and S4: sintering the second mixture in solid phase at 350° C. to 900° C. to obtain lithium manganese iron phosphate LiMnxFe1−x−yPO4, wherein 0≤x≤1, and 0≤y≤1. The method of the present invention can be used to prepare a lithium manganese iron phosphate material with high tap density, long cycle life, low costs, and high cost-effectiveness.

The present application relates to an electrolyte, an electrochemical device and an electronic device comprising the same. The electrolyte of the present application includes a cyclic N-containing sulfonyl-compound and at least one of vinylene carbonate, fluoroethylene carbonate, lithium tetrafluoroborate, lithium difluoro(oxalato)borate or lithium difluorophosphate. The electrolyte of the present application may further include a sulfur-oxygen double bond containing compound and a silicon-containing carbonate. Compared with the prior art, using the electrolyte provided by the present application can effectively improve the high-temperature storage, cycle performance and overcharge performance of an electrochemical device, such as a lithium-ion battery.

Methods of making a lithium mixed metal compound by reaction of starting materials are provided. The methods can include reacting and/or processed reacted starting materials to form the lithium mixed metal compound in the presence of a fluorine rich atmosphere or media.

Methods of making a lithium mixed metal compound by reaction of starting materials are provided. The methods can include reacting and/or processed reacted starting materials to form the lithium mixed metal compound in the presence of a fluorine rich atmosphere or media.

The present invention discloses a preparation method for water-soluble potassium polymetaphosphate, and relates to the technical field of potassium polymetaphosphate production and preparation. In the present invention, potassium dihydrogen phosphate is mixed with a divalent cationic metal oxide at a mixing mass ratio of 70-90:5-18 to obtained a mixture, wherein the divalent cationic metal oxide is one or more of calcia, magnesia and zinc oxide in the field of food processing; then the mixture is heated and melted, and the temperature is kept constant for 1-3 h at a temperature of 600-700° C.; and after temperature keeping, the melted mixture is cooled naturally to obtain a product. The water-soluble potassium polymetaphosphate prepared by the present invention has a high water solubility and effectively solves the application defect of a traditional potassium polymetaphosphate product which is insoluble in water.

A method of making a proppant-gel matrix comprising: a) hydrating a gelling agent to form a hydrated gelling agent; b) adding a basic compound to the hydrated gelling agent to form a basic hydrated gelling agent having a pH in the range of 11.5 to 14.0; c) mixing the basic hydrated gelling agent and a proppant to form a basic hydrated gelling system; and d) adding a crosslinking agent to the basic hydrated gelling system to form the proppant-gel matrix, is disclosed. The proppant-gel matrix can then be used as a fracturing fluid in a hydraulic fracturing process.

The technology concerns methods for stabilizing slurries and/or electrophoretic deposition (EPD) bath suspensions for the preparation of electrodes and/or separation area or any other coating and specifically, to electrodes and separators for use in energy storage devices.

The technology concerns methods for stabilizing slurries and/or electrophoretic deposition (EPD) bath suspensions for the preparation of electrodes and/or separation area or any other coating and specifically, to electrodes and separators for use in energy storage devices.