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CN-122000352-A - Positive electrode active material and lithium ion secondary battery

CN122000352ACN 122000352 ACN122000352 ACN 122000352ACN-122000352-A

Abstract

The purpose of the present invention is to provide a Fe-based positive electrode active material capable of high-voltage operation, and a lithium ion secondary battery comprising the positive electrode active material. The positive electrode active material and the lithium ion secondary battery contribute to energy efficiency. The positive electrode active material of the present invention contains a lithium-iron complex fluoride as a main component and carbon, and the lithium-iron complex fluoride is represented by the following formula (1). In the formula (1) of Li x FeF (3+x) (1), x is a number satisfying 0.4≤x≤1.2.

Inventors

  • JI XIAN
  • Okayama Ryuya
  • ASO SHOGO
  • KUDO TAKASHI
  • Sakakura Ichikuang
  • YUKI CHIBA
  • It is of a specified duration that Tanaka feels
  • FURUKAWA ATSUSHI
  • Furuta terunori
  • MORITA YOSHIYUKI

Assignees

  • 本田技研工业株式会社

Dates

Publication Date
20260508
Application Date
20251103
Priority Date
20241106

Claims (7)

  1. 1. A positive electrode active material comprising a lithium-iron complex fluoride as a main component and carbon, The lithium iron complex fluoride is represented by the following formula (1), Li x FeF (3+x) (1) In the formula (1), x is a number satisfying 0.4≤x≤1.2.
  2. 2. The positive electrode active material according to claim 1, wherein a mass ratio M 1 ：M 2 of the mass M 1 of the lithium iron complex fluoride to the mass M 2 of the carbon is 90:10 to 60:40.
  3. 3. The positive electrode active material according to claim 1, wherein a mass ratio M 1 ：M 2 of the mass M 1 of the lithium iron complex fluoride to the mass M 2 of the carbon is 90:10 to 80:20.
  4. 4. The positive electrode active material according to claim 1, wherein the carbon is a carbon nanotube or carbon black.
  5. 5. A lithium ion secondary battery comprising a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode contains the positive electrode active material according to any one of claims 1 to 4.
  6. 6. The lithium ion secondary battery according to claim 5, wherein the dQ/dV curve of the lithium ion secondary battery at the time of discharge in a charge-discharge cycle has a peak in a range of 3.94 to 4.01V.
  7. 7. A lithium ion secondary battery is characterized by comprising a positive electrode, a negative electrode and an electrolyte, The positive electrode contains a positive electrode active material, The positive electrode active material contains lithium iron complex fluoride as a main component and carbon, The lithium iron complex fluoride is represented by the following formula (1), Li x FeF (3+x) (1) In the formula (1), x is a number which is more than or equal to 0.4 and less than or equal to 1.2, The dQ/dV curve of the lithium ion secondary battery has peaks in the range of 3.94-4.01V during discharging of charge-discharge cycles.

Description

Positive electrode active material and lithium ion secondary battery Technical Field The present invention relates to a positive electrode active material and a lithium ion secondary battery. Background In recent years, research and development on secondary batteries contributing to energy efficiency have been conducted in order to ensure that more people can utilize reliable, sustainable and advanced energy at a proper price. In particular, lithium ion secondary batteries are increasingly important as power sources for Electric Vehicles (EVs), hybrid Electric Vehicles (HEVs), and the like. The positive electrode active material has been attracting attention as an important component for determining the capacity of a lithium ion secondary battery, and development thereof has been advancing. As a positive electrode active material used in a lithium ion secondary battery, for example, iron (Fe) -based lithium iron phosphate (LiFePO 4）.LiFePO4) having a low risk of resources is known to be excellent in cycle characteristics and safety, but has a low voltage and a small capacity, and therefore has a lower energy density (voltage×capacity) expressed as a product of voltage and capacity than a conventionally used nickel (Ni) and cobalt (Co) -based material. For the purpose of high voltage of a battery using a material containing an element with low risk of resources, it has been expected to use an expensive transition metal (for example, notBut instead). However, fe 4+ is very unstable and becomes Fe 3+ due to side reactions, or Fe 4+ requires a very large amount of energy and cannot be produced in some cases. Therefore, even if a compound of Fe 3+ is used as the positive electrode active material, high-voltage operation is not necessarily possible. For example, non-patent document 1 reports that LiFeF 3 is generated during charge and discharge by using iron fluoride (FeF 3), and the average discharge voltage is 3.1V. Non-patent document 2 reports that LiFeO 2 can be expected to have a high energy density. Prior art literature Non-patent literature Non-patent literature 1：F. Badway, et al., "Carbon Metal Fluoride Nanocomposites" J. Electrochem. Soc., 150(10) A1318-A1327 (2003) Non-patent literature 2：Y. Hu, et al., "A Simple, Quick and Eco-Friendly Strategy of Synthesis Nanosizedα-LiFeO2 Cathode with Excellent Electrochemical Performance for Lithium-Ion Batteries" Materials, 11, 1176 (2018) Disclosure of Invention Technical problem to be solved by the invention In non-patent document 2, the actual voltage is about 2.5V, which is lower than the expected voltage. The average discharge voltage (3.1V) of non-patent document 1 is also lower than the voltage of LiFePO 4, and there is room for improvement for further higher voltages. The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an Fe-based positive electrode active material capable of high-voltage operation and a lithium ion secondary battery including the same. Further, the resource risk is further reduced, contributing to the cost reduction. Technical scheme for solving technical problems In order to achieve the above object, the present invention provides the following technical solutions. [1] A positive electrode active material comprising a lithium-iron complex fluoride as a main component and carbon, The lithium iron complex fluoride is represented by the following formula (1): LixFeF(3+x) (1) In the formula (1), x is a number satisfying 0.4≤x≤1.2. [1] The positive electrode active material according to the present invention has a high average discharge voltage and can operate at a high voltage. Therefore, in the lithium ion secondary battery including the positive electrode active material, the number of batteries required can be reduced, contributing to cost reduction. [2] The positive electrode active material according to [1], wherein a mass ratio (M 1：M2) of the mass (M 1) of the lithium iron complex fluoride to the mass (M 2) of the carbon is 90:10 to 60:40. [2] The positive electrode active material can increase the capacity of a lithium ion secondary battery containing the positive electrode active material, and can further improve the energy density. [3] The positive electrode active material according to [1] or [2], wherein a mass ratio (M 1：M2) of the mass (M 1) of the lithium iron complex fluoride to the mass (M 2) of the carbon is 90:10 to 80:20. [3] The positive electrode active material can increase the capacity of a lithium ion secondary battery containing the positive electrode active material, and can further improve the energy density. [4] The positive electrode active material according to any one of [1] to [3], wherein the carbon is a carbon nanotube or carbon black. [4] The positive electrode active material can increase the capacity of a lithium ion secondary battery containing the positive electrode active material, and can further improve the energy density.