KR-20260063117-A - LITHIUM MANGANESE IRON PHOSPHATE CATHOD MATERIAL WITH CONTROLLED CRYSTAL PLANE AND MANUFACTURING METHOD THEREOF

KR20260063117AKR 20260063117 AKR20260063117 AKR 20260063117AKR-20260063117-A

Abstract

In the process of manufacturing lithium iron manganese phosphate, a chelating agent is used as an additive to produce an asymmetric lithium iron manganese phosphate cathode material in which the interplanar distance in the b-axis direction of lithium ion movement is shortened, thereby improving the ion conductivity of the lithium iron manganese phosphate cathode material. This invention discloses a lithium iron manganese phosphate cathode material with controlled crystal planes and a method for manufacturing the same. A method for manufacturing a lithium iron manganese phosphate cathode material with controlled crystal planes according to the present invention comprises: (a) a step of dissolving an iron precursor and a manganese precursor in a solvent to form a first precursor mixed solution; (b) a step of adding a phosphorus precursor and a chelating agent to the first precursor mixed solution to form a second precursor mixed solution; (c) a step of adding a lithium precursor to the second precursor mixed solution and then reacting it in a water bath or hydrothermally; and (d) a step of filtering or centrifuging the product of the water bath or hydrothermal reaction and then heat-treating it in an inert gas atmosphere to form lithium iron manganese phosphate powder.

Inventors

천진녕
안병준
송보예

Assignees

한국세라믹기술원

Dates

Publication Date: 20260507
Application Date: 20241030

Claims (10)

(a) a step of dissolving an iron precursor and a manganese precursor in a solvent to form a first precursor mixture solution; (b) a step of forming a second precursor mixed solution by adding a phosphorus precursor and a chelating agent to the first precursor mixed solution; (c) a step of adding a lithium precursor to the second precursor mixture solution and then reacting it in a water bath or hydrothermal reaction; and (d) A step of filtering or centrifuging the product of the above water bath or hydrothermal reaction, and then heat-treating it in an inert atmosphere to form lithium iron manganese phosphate powder; Characterized by including, Method for manufacturing a lithium manganese iron phosphate cathode material with controlled crystal planes.
In paragraph 1, In step (a) above, Each of the above iron precursor and manganese precursor is characterized by comprising one or more selected from compounds of the sulfate series, nitrate series, halide series, hydroxide series, acetate series, and alkoxide series. Method for manufacturing a lithium manganese iron phosphate cathode material with controlled crystal planes.
In paragraph 1, In step (b) above, the phosphorus precursor comprises one or more selected from phosphoric acid ( H₃PO₄ ), lithium phosphate ( Li₃PO₄ ) , and ammonium phosphate series compounds (ammonium phosphate), and In step (b) above, the phosphorus precursor is added to the first precursor mixture solution and then a chelating agent is added, or the phosphorus precursor is added to the first precursor mixture solution and then a chelating agent is added. Method for manufacturing a lithium manganese iron phosphate cathode material with controlled crystal planes.
In paragraph 1, In step (b) above, The above chelating agent Characterized by comprising one or more selected from ascorbic acid, citric acid, oxalic acid, gluconic acid, malic acid, tartaric acid, and water-soluble organic acids. Method for manufacturing a lithium manganese iron phosphate cathode material with controlled crystal planes.
In paragraph 4, The above chelating agent Characterized by adding 1/20 to 1/2 times the total moles of the iron precursor and manganese precursor, Method for manufacturing a lithium manganese iron phosphate cathode material with controlled crystal planes.
In paragraph 1, In step (b) above, a carbon coating additive is further added together with the chelating agent, and The carbon coating additive is characterized by comprising one or more selected from sucrose, glucose, galactose, cellulose, and xylose. Method for manufacturing a lithium manganese iron phosphate cathode material with controlled crystal planes.
In paragraph 1, In step (c) above, The above lithium precursor Characterized by comprising one or more selected from lithium hydroxide (LiOH), lithium carbonate ( Li₂CO₃ ), lithium phosphate ( Li₃PO₄ ), lithium chloride (LiCl) , and lithium sulfate ( Li₂SO₄ ). Method for manufacturing a lithium manganese iron phosphate cathode material with controlled crystal planes.
In paragraph 1, The above water bath or hydrothermal reaction Characterized by being carried out at 120 to 180℃, Method for manufacturing a lithium manganese iron phosphate cathode material with controlled crystal planes.
In paragraph 1, In step (d) above, the inert atmosphere is an atmosphere maintained by one or more of nitrogen, argon, and vacuum, and In step (d) above, the heat treatment is characterized by being performed for 1 to 12 hours at a temperature of 500 to 900℃. Method for manufacturing a lithium manganese iron phosphate cathode material with controlled crystal planes.
A lithium iron manganese phosphate cathode material with controlled crystal planes manufactured by a method according to any one of claims 1 to 9, When manufacturing the above lithium iron manganese phosphate cathode material, a chelating agent is used as an additive to shorten the interplanar distance in the b-axis direction, thereby having an asymmetric shape, and The above lithium iron manganese phosphate cathode material is a lithium iron manganese phosphate cathode material with controlled crystal planes, characterized by having an olivine crystal structure satisfying Formula 1 below. Equation 1: LiMn x Fe 1-x PO 4 (where, < x ≤ 1)

Description

Lithium Manganese Iron Phosphate Cathode Material with Controlled Crystal Plane and Manufacturing Method Thereof The present invention relates to a lithium manganese phosphate cathode material with controlled crystal planes and a method for manufacturing the same. More specifically, the invention relates to a lithium manganese phosphate cathode material with controlled crystal planes and a method for manufacturing the same, wherein the ion conductivity of the lithium manganese phosphate cathode material can be improved by using a chelating agent as an additive during the manufacturing process of the lithium manganese phosphate to produce an asymmetric lithium manganese phosphate cathode material in which the interplanar distance in the b-axis direction, where lithium ions move, is shortened. Lithium iron phosphate ( LiFePO4 , LFP) cathode materials having an olivine crystal structure have high structural stability because the lattice within the structure does not collapse during lithium ion insertion/extraction, and they can block ignition due to excellent thermal stability. In addition, lithium iron phosphate cathode materials have a production cost that is about 30% lower than that of conventional ternary (NCM) cathode materials, making them advantageous for securing price competitiveness. They also have the advantage of not having a large fluctuation range in raw material prices compared to the core minerals of conventional ternary cathode materials. Compared to conventional ternary cathode materials, these lithium iron phosphate cathode materials have lower theoretical capacity and operating voltage (~3.2V), and exhibit a relatively low energy density of 140 to 160 Wh/kg. To address this, lithium manganese iron phosphate (LiMn x Fe 1-x PO 4 , LMFP), which has a higher operating voltage (~4.0V) by introducing manganese (Mn) elements into the iron (Fe) element positions of lithium iron phosphate, is recently attracting attention as a new cathode material. This lithium iron manganese phosphate is expected to be applied to batteries for mid-to-low-priced electric vehicles, as its energy density is improved to 170 to 190 Wh/kg due to the effect of improving operating voltage. However, lithium iron manganese phosphate cathode materials have a one-dimensional lithium ion transport path, resulting in a low lithium ion diffusion coefficient and low electrical conductivity at room temperature, which leads to poor output characteristics and requires a solution. A relevant prior art document is Korean Patent Publication No. 10-2024-0025653 (published on February 27, 2024), which describes a lithium iron manganese phosphate cathode active material, a method for manufacturing the same, a cathode sheet, a secondary battery, and an electric device. FIG. 1 is a process flowchart showing a method for manufacturing a lithium iron manganese phosphate cathode material with controlled crystal planes according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating the principle of crystal plane control of lithium iron manganese phosphate cathode particles manufactured by a method according to an embodiment of the present invention. Figure 3 is an SEM image showing lithium iron manganese phosphate powder prepared according to Comparative Example 1. Figures 4 and 5 are SEM images showing lithium iron manganese phosphate powder prepared according to Examples 2 and 4. Figure 6 is a graph showing the XRD measurement results for lithium iron manganese phosphate powder prepared according to Examples 1 to 3 and Comparative Example 1. Figure 7 is a graph showing the XRD measurement results for the lithium iron manganese phosphate powder prepared according to Example 4 and Comparative Example 1. 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. Throughout the specification, the same reference numerals refer to the same components. The following is a detailed description of a lithium iron manganese phosphate cathode material with controlled crystal planes and a method for manufacturing the same according to a preferred embodiment of the present invention, with reference to the attached drawings. FIG. 1 is a process flowchart showing a method for manufacturing a lithium iron manganese phosphate cathode material with controlled crystal planes according to an embodiment of the present invention, and FIG. 2 is a schematic diagram explaining the principle of controlling the crystal p