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JP-7857102-B2 - Lithium cathode active material

JP7857102B2JP 7857102 B2JP7857102 B2JP 7857102B2JP-7857102-B2

Inventors

  • ホイベアウ・ヨーナタン
  • ホイ・ヤコプ・ヴァイラント
  • エルケーア・クレスチャン・フィンク
  • ロネゴー・ラース・フェール
  • デール・セーアン

Assignees

  • トプソー・バッテリー・マテリアルズ・アクティーゼルスカブ

Dates

Publication Date
20260512
Application Date
20191218
Priority Date
20181219

Claims (20)

  1. a. A step of providing a precursor for producing a lithium cathode active material having the chemical composition Li x Ni y Mn 2-y O 4 (where 0.95 ≤ x ≤ 1.05; and 0.43 ≤ y ≤ 0.47); wherein the precursor contains Li, Ni, and Mn in the ratio Li:Ni:Mn:X:Y:2-Y, where 0.95 ≤ X ≤ 1.05; and 0.42 ≤ Y <0.5; b. A step of heating the precursor from step a to a temperature of 500°C to 1200°C to sinter the precursor and obtain the sintered product. c. The process includes cooling the sintered product from step b to room temperature, wherein during the cooling of step c, the temperature is maintained at intervals of 750 to 650°C for a time sufficient to obtain at least 94% phase purity of the lithium cathode active material. A method for producing lithium positive electrode active material for high-voltage secondary batteries, The lithium cathode active material comprises at least 94% by mass of spinel. The spinel has the chemical composition Li x Ni y Mn 2-y O 4 , where, 0.95 ≤ x ≤ 1.05; 0.43 ≤ y ≤ 0.47; Herein, the lithium cathode active material is synthesized from a precursor containing Li, Ni, and Mn in the ratio Li:Ni:Mn:X:Y:2-Y, where 0.95≦X≦1.05 and 0.42≦Y＜0.5, in a method for producing the lithium cathode active material.
  2. A method for producing a lithium cathode active material according to claim 1, wherein y ≈ 0.97 < Y < y ≈ 1.06.
  3. A method for producing a lithium cathode active material according to claim 1 or 2, wherein 0.42 ≤ Y < 0.49.
  4. A method for producing a lithium cathode active material according to any one of claims 1 to 3, wherein at least 90% by mass of the spinel is crystallized in a disordered space group Fd-3m.
  5. A method for producing a lithium positive electrode active material according to any one of claims 1 to 4, wherein the lithium positive electrode active material in the half-cell has a potential difference of at least 50 mV between 25% and 75% of its capacity, exceeding 4.3 V during discharge at a current of 29 mA/g.
  6. A method for producing a lithium cathode active material according to any one of claims 1 to 5, wherein the lithium cathode active material is calcined so that its lattice constant a is between 8.171 and 8.183 Å.
  7. The method for producing a lithium cathode active material according to claim 6, wherein the lattice constant a is between (-0.1932y + 8.2613) Å and 8.183 Å.
  8. The method for producing a lithium cathode active material according to claim 6, wherein the lattice constant a is between (-0.1932y + 8.2613) Å and (-0.1932y + 8.2667) Å.
  9. The method for producing a lithium cathode active material according to claim 6, wherein the lattice constant a is between (-0.1932y + 8.2613) Å and (-0.1932y + 8.2641) Å.
  10. A method for producing a lithium cathode active material according to any one of claims 1 to 9 , wherein the lithium cathode active material has a tap density of 2.2 g/cm³ or more.
  11. A method for producing a lithium cathode active material according to any one of claims 1 to 10, wherein the lithium cathode active material is composed of particles, and the D50 of the particles of the lithium cathode active material satisfies 3 μm < D50 < 12 μm.
  12. A method for producing a lithium cathode active material according to any one of claims 1 to 11, wherein the BET area of the lithium cathode active material is less than 1.5 m² /g.
  13. A method for producing a lithium cathode active material according to any one of claims 1 to 12, characterized in that the lithium cathode active material is composed of particles, and the particles have an average aspect ratio of less than 1.6.
  14. A method for producing a lithium cathode active material according to any one of claims 1 to 13, characterized in that the lithium cathode active material is composed of particles, and the particles have a roughness of less than 1.35.
  15. A method for producing a lithium cathode active material according to any one of claims 1 to 14, characterized in that the lithium cathode active material is composed of particles, and the particles have a circularity of 0.6 or greater.
  16. A method for producing a lithium cathode active material according to any one of claims 1 to 15, characterized in that the lithium cathode active material is composed of particles, and the particles have an area envelope degree greater than 0.8.
  17. A method for producing a lithium cathode active material according to any one of claims 1 to 16, characterized in that the lithium cathode active material is composed of particles, and the particles have a porosity of less than 3%.
  18. A method for producing a lithium cathode active material according to any one of claims 1 to 17, wherein 0.99 ≤ x ≤ 1.01.
  19. A method for producing a lithium cathode active material according to any one of claims 1 to 18, wherein the lithium cathode active material has a capacity of at least 138 mAh/g and a maximum of 142 mAh/g when discharged at 74 mA/g (0.5 C) in a half-cell between 3.5 V and 5 V at 55°C.
  20. A method for producing a lithium cathode active material according to any one of claims 1 to 19, wherein the lithium cathode active material has a capacity of at least 138 mAh/g and a maximum of 140 mAh/g when discharged at 74 mA/g (0.5 C) in a half-cell between 3.5 V and 5 V at 55°C.

Description

Field of Invention This invention relates to lithium cathode active materials for use in high-voltage lithium secondary batteries. In particular, this invention relates to such materials having high capacity, high voltage, and low decomposition properties relative to the Li/Li+ standard. Furthermore, this invention relates to a method for producing such materials. Background: Lithium cathode active material (cathode active material) can be characterized by the following formula: Li x Ni y Mn 2-y O 4-δ , where 0.9 ≤ x ≤ 1.1, 0.4 ≤ y ≤ 0.5, and 0 ≤ δ ≤ 0.1. Such materials can be used, for example, in portable devices (US8,404,381B2); electric vehicles, energy storage systems, auxiliary power units, and uninterruptible power supplies. Lithium cathode active materials are recognized as future successors to lithium secondary battery cathode materials such as LiCoO 2 and LiMn 2 O 4 . Lithium cathode active materials can be produced from one or more precursors obtained by co-deposition. Both the precursors and products are spherical due to the co-deposition process. Electrochimica Acta (2014), pp. 290-296 discloses a material produced by sequential sintering (heat treatment) at 500°C and then 800°C after an initial heat treatment step (500°C). The resulting product exhibits high crystallinity and a spinel structure after the initial heat treatment step (500°C). Uniform morphology, a tap density of 2.03 gcm⁻³ , and a uniform secondary particle size of 5.6 μm are observed in the product. According to Electrochimica Acta (2004), pp. 939-948, uniformly distributed spherical particles exhibit a higher tap density in terms of fluidity and ease of packing compared to disordered particles. In this LiNi 0.5 Mn 1.5 O 4 , it is hypothesized that the hierarchical morphology and the large size of the secondary particles contributed to the increased tap density. As disclosed in US 8,404,381B2 and US 7,754,384B2, lithium cathode active materials can also be produced from precursors obtained by mechanically mixing starting materials to form a homogeneous mixture. The precursor is heated to 600°C, annealed at 700–950°C, and cooled in an oxygen-containing medium. The 600°C heat treatment step is disclosed as necessary to adequately incorporate lithium into the mixed nickel and manganese oxide precursor. It is also disclosed that annealing is generally performed at temperatures above 800°C to remove oxygen while forming the desired spinel morphology. Furthermore, it is disclosed that oxygen can be partially restored by cooling in an oxygen-containing medium. US 7,754,384B2 does not describe the tap density of the material. It is disclosed that an excess amount of lithium of 1–5 mol% is used to produce the precursor. J. Electrochem. Soc. (1997) 144, 144, pp. 205-213) also discloses the production of spinel LiNi 0.5 Mn 1.5 O 4 from a precursor prepared by mechanically mixing starting materials to obtain a homogeneous mixture. The precursor is heated in air three times at 750°C and once at 800°C. It is disclosed that heating above 650°C causes LiNi 0.5 Mn 1.5 O 4 to lose oxygen and become disproportionate, however, slow cooling in an oxygen-containing atmosphere restores the stoichiometry of LiNi 0.5 Mn 1.5 O 4. Particle size and tap density are not disclosed. It is also disclosed that the production of spinel phase materials by mechanically mixing starting materials to obtain a homogeneous mixture is difficult, and that precursors prepared by the sol-gel method are preferred. US8,404,381B2US7,754,384B2US7,754,384B2 Electrochimica Acta (2004), pp939-948J. Electrochem. Soc. (1997) 144, 144, pp205-213) A "spinel" is a crystal lattice in which oxygen atoms are arranged in a slightly distorted cubic close-packed lattice, with cations occupying octahedral and tetrahedral sites in the interstitial gaps within the lattice. Oxygen and octahedral-coordinate cations form a skeletal structure with a three-dimensional channel system occupying the tetrahedral-coordinate cations. In a spinel-type structure, the ratio of tetrahedral-coordinate cations to octahedral-coordinate cations is approximately 1:2, and the ratio of cations to oxygen is approximately 3:4. The cations at the octahedral sites may consist of a single element or a mixture of different elements. When a mixture of different types of octahedral-coordinate cations forms a three-dimensional periodic lattice itself, the spinel is called an ordered spinel. When the cations are more randomly distributed, the spinel is called a disordered spinel. Examples of ordered and disordered spinels described in the P4332 space group and the Fd-3m space group, respectively, can be found in Adv. Mater. Disclosed in (2012) 24, pp. 2109-2116. A "salt-type" crystal lattice is one in which oxygen atoms are arranged in a slightly distorted cubic close-packed lattice, and cations completely occupy the octahedral sites within the lattice. Cations can consist of a single element or a mixture of different el