KR-20260065022-A - Method for preparing positive electrode active material for sodium secondary battery

Abstract

The present invention provides a method for manufacturing a positive electrode active material for a sodium secondary battery, comprising: a) a step of loading a mixture of a composite transition metal precursor and a sodium compound into a crucible; and b) a step of placing the crucible into a furnace and firing it to manufacture a positive electrode active material, wherein in step a), the height of the mixture loaded is within 50 mm from the bottom of the crucible.

Inventors

• 권용환
• 이동욱
• 박아람

Assignees

• 주식회사 에코프로비엠

Dates

Publication Date

20260508

Application Date

20241031

Claims (5)

1. a) a step of loading a mixture of a complex transition metal precursor and a sodium compound into a crucible; and b) A step of introducing the above crucible into a furnace and firing to produce an anode active material, and A method for manufacturing a positive electrode active material for a sodium secondary battery, wherein, in step a) above, the height of the loaded mixture is within 50 mm from the bottom of the crucible.
2. In paragraph 1, A method for manufacturing a positive electrode active material for a sodium secondary battery, wherein, in step a) above, the mixture is mixed such that the molar ratio (Na/M) of sodium of the sodium compound to the total metal of the composite transition metal precursor is 0.8 to 1.2.
3. In paragraph 1, A method for manufacturing a positive electrode active material for a sodium secondary battery, wherein, in step a) above, the crucible has a rectangular cross-sectional shape with a length ratio (width × length × height) of 1:0.9 to 1.1:0.3 to 0.4.
4. In paragraph 1, A method for manufacturing a positive electrode active material for a sodium secondary battery, wherein the calcination of step b) above is performed at 700 to 1,100°C for 6 to 20 hours.
5. In paragraph 1, A method for manufacturing a positive electrode active material for a sodium secondary battery, wherein, in step b) above, the residual sodium content of the manufactured positive electrode active material is less than 4,000 ppm.

Description

Method for preparing positive electrode active material for sodium secondary battery The present invention relates to a method for manufacturing a positive electrode active material for a sodium secondary battery. Lithium-ion rechargeable batteries have been widely used as energy storage devices in various fields of electronic technology. Recently, with the surge in demand for lithium-ion batteries, sodium-ion rechargeable batteries are attracting attention as a replacement for lithium, an expensive metal. Because sodium-ion rechargeable batteries utilize an insertion/extraction reaction operating principle similar to that of lithium-ion batteries, they are one of the next-generation materials with high potential for application as rechargeable batteries. Meanwhile, unreacted sodium byproducts ( Na₂CO₃ , NaOH , etc.) that remain in large quantities on the particle surface during the calcination of the cathode active material degrade the electrochemical performance of the battery, such as by generating gas due to side reactions in the electrolyte during battery operation and reducing the capacity and output of the cathode material. Conventionally, methods have been applied to remove byproducts from the surface of the cathode active material by washing with distilled water or ethanol, but there are limitations in sufficiently removing residual sodium, and there are problems such as the detachment of sodium ions present in the cathode active material and damage to the particle surface during the washing process. The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Unless otherwise defined, all terms used in this specification (including technical and scientific terms) may be used in a meaning that is commonly understood by those skilled in the art to which the present invention belongs. When a part of a specification is described as "including" a certain component, unless specifically stated otherwise, this means that it does not exclude other components but may include additional components. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. In this specification, "A to B" means "A or more and B or less" unless specifically defined otherwise. Additionally, "A and/or B" means at least one selected from the group consisting of A and B, unless specifically defined otherwise. Additionally, when a part such as a layer, film, region, plate, etc. is described in this specification as being “on” or “on” another part, this includes not only cases where it is “immediately on” another part, but also cases where there is another part in between. One embodiment of the present invention provides a method for manufacturing a positive electrode active material for a sodium secondary battery, comprising the steps of: a) loading a mixture of a composite transition metal precursor and a sodium compound into a crucible; and b) placing the crucible into a furnace and firing it to manufacture a positive electrode active material. In step a) above, the height of the loaded mixture is characterized by being within 50 mm from the bottom of the crucible, and specifically, it may be 10 to 50 mm from the bottom of the crucible, preferably 20 to 50 nm. In the present invention, by controlling the optimal height of the raw material mixture for manufacturing the anode active material loaded into the crucible to 50 mm or less, the unreacted sodium byproduct remaining on the surface of the manufactured anode active material is reduced to less than 4,000 ppm. As in one embodiment, in step a), the crucible may have a rectangular cross-sectional shape with a length ratio (width × length × height) of 1:0.9 to 1.1:0.3 to 0.4, and specifically, the crucible may be a container having a rectangular cross-sectional shape with a length ratio (width × length × height) of 330mm × 330mm × 120mm. In addition, generally, the shape of the crucible can be a round or square container, and although a square container was used in the present invention, it is not necessarily limited thereto. As in one embodiment, in step a), the mixture may be mixed such that the molar ratio (Na/M) of sodium of the sodium compound to the total metal of the composite transition metal precursor is 0.8 to 1.2, and specifically, the Na/M ratio may be 0.9 to 1.1. Accordingly, an O3-type cathode active material can be manufactured, and although the O3-type cathode active material has a high energ