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KR-20260065736-A - Cathode material, method of manufacturing the same, positive plate, and sodium ion battery

KR20260065736AKR 20260065736 AKR20260065736 AKR 20260065736AKR-20260065736-A

Abstract

The present application provides a cathode material, a method for manufacturing the same, a cathode plate, and a sodium ion battery. The cathode material comprises composite particles, wherein the molecular formula of the composite particles is Na x Fe y (PO 4 ) n (P 2 O 7 ) m , wherein x is 4.2 to 4.5, y is 3.2 to 3.5, n is 2.2 to 2.5, and m is 0.9 to 1.1; the composite particles comprise an olivine-type phosphate and a polyanionic phosphate coated on the surface of the olivine-type phosphate, wherein the molar ratio of the olivine-type phosphate to the polyanionic phosphate is (0.2 to 0.5):1. The present application significantly improves the capacity of the cathode material by optimizing the molar ratio of the olivine-type phosphate to the polyanionic phosphate in an iron-based composite phosphate material and simultaneously designing the microstructure of the composite particles formed by both, thereby realizing nanocrystallization in the crystal structure and two-phase interfacial penetration.

Inventors

  • 펑, 탕핑
  • 엘브이, 페이
  • 엘브이, 후이후이

Assignees

  • 후베이 완런 뉴 에너지 테크놀로지 코.,엘티디.

Dates

Publication Date
20260511
Application Date
20241104
Priority Date
20241031

Claims (10)

  1. As a cathode material, The above-mentioned cathode material comprises composite particles, wherein the molecular formula of the composite particles is Na x Fe y (PO 4 ) n (P 2 O 7 ) m , wherein x is 4.2–4.5, y is 3.2–3.5, n is 2.2–2.5, and m is 0.9–1.1; The above composite particle comprises an olivine-type phosphate and a polyanionic-type phosphate coated on the surface of the olivine-type phosphate, wherein the molar ratio of the olivine-type phosphate to the polyanionic-type phosphate is (0.2 to 0.5):1, characterized in that it is an anode material.
  2. In paragraph 1, A cathode material characterized by a molar ratio of the olivine-type phosphate to the polyanionic-type phosphate being (0.2~0.4):1.
  3. In paragraph 1 or 2, The above-described cathode material further comprises a carbon layer coated on the surface of the composite particle, wherein, when the total weight of the cathode material is calculated as 100%, the mass fraction of the carbon layer is 1.5% to 3.0%; Preferably, the carbon layer is an amorphous carbon portion formed from an organic carbon source and/or an inorganic carbon portion formed from an inorganic carbon source; More preferably, the carbon layer is a combination of the amorphous carbon part and the inorganic carbon part, wherein the weight ratio of the inorganic carbon part is 2.5% to 5.0% when the total weight of the carbon layer is calculated as 100%.
  4. In any one of paragraphs 1 through 3, A cathode material characterized by the powder resistivity of the above cathode material being 12,000 Ω·cm to 93,000 Ω·cm.
  5. As a method for manufacturing a cathode material, A step of preparing a sodium source, an iron source, and a phosphorus source into a first slurry; A step of obtaining a precursor by subjecting the above first slurry to first drying and first calcination; A step of preparing the above precursor and carbon source into a second slurry; and A method for manufacturing an anode material characterized by including the step of obtaining the anode material by subjecting the second slurry to second drying and second calcination.
  6. In paragraph 5, In the first slurry above, the molar ratio of sodium, iron, and phosphorus elements is (4.2–4.86):(3.2–3.5):(4.2–4.5); Preferably, the first firing comprises a first firing and a second firing performed sequentially, wherein The temperature of the first firing is 400℃ to 500℃ and the time is 1.5h to 2.5h, the temperature of the second firing is 550℃ to 650℃ and the time is 10h to 14h; More preferably, a method for manufacturing an anode material characterized in that the first firing is performed in a protective atmosphere.
  7. In paragraph 6, The sodium source is one or more selected from sodium bicarbonate, sodium phosphate, sodium monohydrogen phosphate, and sodium dihydrogen phosphate; the iron source is one or more selected from anhydrous iron phosphate, polyhydrate iron phosphate, iron monohydrogen phosphate, and ferrous oxalate; and the phosphorus source is one or more selected from anhydrous iron phosphate, ammonium dihydrogen phosphate, sodium phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, polyhydrate iron phosphate, and iron monohydrogen phosphate; Preferably, the carbon source comprises an organic carbon source and/or an inorganic carbon source; Preferably, the organic carbon source is one or more selected from citric acid, glucose, sucrose, soluble starch, and polyethylene glycol; and/or, the inorganic carbon source is one or more selected from graphite, carbon nanotubes, and graphene; Preferably, the carbon source comprises the soluble starch, the polyethylene glycol, and the graphene; More preferably, a method for manufacturing an anode material characterized in that the polyethylene glycol is PEG-2000.
  8. In any one of paragraphs 5 through 7, The above second firing includes a first stage firing, a second stage firing, a third stage firing, and a fourth stage firing performed sequentially, wherein In the first stage firing above, the temperature is 40℃ to 60℃ and the holding time is 1h to 2h; In the above second stage firing, the temperature is 100℃ to 130℃ and the holding time is 0.5h to 1.5h; In the above third stage firing, the temperature is 180℃ to 210℃ and the holding time is 2h to 4h; In the above fourth stage firing, the temperature is 500℃ to 600℃ and the holding time is 2h to 6h; Preferably, a method for manufacturing an anode material characterized in that the heating rate of the first stage firing, the second stage firing, the third stage firing, and the fourth stage firing is independently 3℃/min to 10℃/min.
  9. A positive plate characterized by comprising a positive material according to any one of claims 1 to 4, or a positive material manufactured by a method for manufacturing a positive material according to any one of claims 5 to 8.
  10. A sodium ion battery characterized by including a positive plate according to claim 9.

Description

Cathode material, method of manufacturing the same, positive plate, and sodium ion battery The present invention relates to the field of sodium ion battery technology, and specifically, to a positive electrode material, a method for manufacturing the same, a positive electrode plate, and a sodium ion battery. In recent years, people have devoted significant effort to developing cost-effective and high-performance cathode materials to realize commercially viable sodium-ion batteries (e.g., in the field of new energy vehicles). In a similar field, namely the field of lithium-ion batteries, LiFePO4 cathodes have achieved massive commercial success in lithium-ion batteries, and this type of iron-based phosphate material is considered one of the most suitable choices for cathode active materials in secondary batteries because of its excellent performance and low cost. However , the thermodynamic properties of olivine-type NaFePO4 (NFP) are poor, and it is considered to be electrochemically inert. In contrast, pyrophosphate Na2FeP2O7materialshave open three-dimensional Na + channels in their microstructure, and at the same time , P2O74- within the crystal has a strong inductive effect, allowing the material to have a higher operating voltage (~3.0V), but the low reversible capacity (< 100mAh · g1 ) of Na2FeP2O7 poses a serious impediment to actual applications. Whether olivine-type phosphate or polyanionic-type phosphate, when used as positive electrode active materials for sodium-ion batteries, both have certain disadvantages and lack corresponding battery performance expression. Currently, existing technology provides polyanionic cathode materials comprising a phosphate and a carbon layer coated on the surface of the phosphate, wherein the phosphate includes NFPP, NFP, and NNFPO, and the content ratio of NFP and NNFPO is controlled through multiple short-time sintering steps. However, the provided technical solution only reduces the impurity phase of the cathode material and fails to achieve synergistic effects between different crystal phases, so the performance of the obtained cathode material still needs to be improved. Based on this, designing the cathode active material of a sodium ion battery at the crystal phase level to achieve superior electrochemical performance is one of the important technical challenges to be solved in this field. Hereinafter, the drawings used in this application are briefly described to more clearly explain the technical solution of this application. The drawings described below are merely some embodiments of this application, and it is obvious to those skilled in the art that other drawings can be obtained based on these drawings without any creative effort. Figure 1 is an SEM result image of the cathode material obtained in Example 1. Figure 2 is an SEM result image of the cathode material obtained in Example 14. Figure 3 is an SEM result image of the cathode material obtained in Example 15. Figure 4 is a process flow diagram of a method for manufacturing a cathode material according to an embodiment. Hereinafter, embodiments of the technical solution of the present application will be described in detail with reference to the drawings. The following embodiments are merely examples and are used only to more clearly explain the technical solution of the present application; they cannot be used to limit the scope of protection of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as generally understood by those skilled in the art; terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the application; and the terms “comprising” and “having” and any variations thereof in the specification, claims, and description of the drawings are intended to encompass non-exclusive inclusion. In the description of the embodiments of this application, technical terms such as "first," "second," etc., are used merely to distinguish different objects and should not be understood as indicating or implying relative importance, or as implicitly indicating the number, specific order, or priority relationship of the technical features described. In the description of the embodiments of this application, "plural" means two or more unless otherwise explicitly and specifically limited. The term "Examples" as used herein means that specific features, structures, or characteristics described with reference to the Examples may be included in at least one Example of this Application. This phrase, appearing in various places in the Specification, does not necessarily refer to the same Example, nor are they separate or alternative Examples mutually exclusive from other Examples. Those skilled in the art understand, expressly or impliedly, that the Examples described herein may be combined with other Examples. In the embodiments of this application, the term "and/or" merely describes a relate