Search

KR-102963724-B1 - Lithium iron phosphate cathode material, cathode electrode, and method for manufacturing a lithium-ion battery

KR102963724B1KR 102963724 B1KR102963724 B1KR 102963724B1KR-102963724-B1

Abstract

A method for producing a lithium iron phosphate cathode material, a cathode electrode, and a lithium-ion battery. The method comprises: a step of sequentially grinding, spray-drying, and sintering a first mixture slurry of iron phosphate, a lithium source, a carbon source, and a solvent to obtain a spherical first lithium iron phosphate material; a step of sequentially grinding, spray-drying, sintering, and crushing a second mixture slurry of iron phosphate, a lithium source, a carbon source, and a solvent to obtain a second lithium iron phosphate material having an irregular shape; and a step of mixing the first lithium iron phosphate material and the second lithium iron phosphate material in equal mass ratios to obtain a lithium iron phosphate cathode material, wherein the suitable value of the maximum compressive density of the lithium iron phosphate cathode material is C, and C = 0.0847t 1 + 0.0196t 1 - 0.0095t 2 + 0.0261t 2 - 33.6716. T1 and t1 represent the sintering temperature and sintering time of the first lithium iron phosphate material, respectively, and T2 and t2 represent the sintering temperature and sintering time of the second lithium iron phosphate material, respectively, and t1 and t2 are within the range of 7h-11h, T1 is within the range of 760℃-780℃, and T2 is within the range of 770℃-800℃; C is 2.6g/ cm³ or higher.

Inventors

  • 두, 멍이
  • 천, 싼즈
  • 하오, 룽

Assignees

  • 비와이디 컴퍼니 리미티드

Dates

Publication Date
20260513
Application Date
20220926
Priority Date
20210926

Claims (10)

  1. As a method for manufacturing lithium iron phosphate cathode materials, A step of sequentially grinding, spray-drying, and sintering a first mixture slurry of iron phosphate, a lithium source, a carbon source, and a solvent to obtain a first lithium iron phosphate material having a spherical shape - the maximum compressive density of the first lithium iron phosphate material is within the range of 2.01 g/ cm³ - 2.05 g/ cm³ - ; A step of sequentially grinding, spray-drying, sintering, and crushing a second mixture slurry of iron phosphate, a lithium source, a carbon source, and a solvent to obtain a second lithium iron phosphate material having an irregular shape - the maximum compressive density of the second lithium iron phosphate material is within the range of 2.51 g/ cm³ - 2.6 g/ cm³ - ; and A step of obtaining a lithium iron phosphate cathode material by mixing the first lithium iron phosphate material and the second lithium iron phosphate material in equal mass ratios. Including, and if the suitable value of the maximum compressive density of the lithium iron phosphate cathode material is denoted as C, C is given by the following relationship: Satisfying C=0.0847t 1 +0.0196t 1 -0.0095t 2 +0.0261t 2 -33.6716; T1 and t1 each represent the sintering temperature and sintering time of the first lithium iron phosphate material, and T2 and t2 each represent the sintering temperature and sintering time of the second lithium iron phosphate material; t1 and t2 are within the range of 7h-11h, T1 is within the range of 760℃-780℃, and T2 is within the range of 770℃-800℃; and C is within the range of 2.8195g/ cm3-2.8991g / cm3 , method.
  2. A method according to claim 1, wherein the D50 particle size of the first lithium iron phosphate material is 3 μm-10 μm.
  3. A method according to claim 1, wherein the D50 particle size of the second lithium iron phosphate material is 0.5 μm-3 μm.
  4. A method according to claim 1, wherein the D50 particle size of the ground first mixture slurry or the second mixture slurry is in the range of 0.2 μm to 5 μm.
  5. A method according to claim 1, wherein the mole of lithium element in the lithium source is 1.00-1.05 times the mole of iron phosphate.
  6. As a positive plate, A positive plate comprising a lithium iron phosphate positive material produced by a method according to any one of claims 1 to 5.
  7. As a lithium-ion battery, A lithium-ion battery including a positive plate according to paragraph 6.
  8. delete
  9. delete
  10. delete

Description

Lithium iron phosphate cathode material, cathode electrode, and method for manufacturing a lithium-ion battery Cross-reference of related applications The present disclosure claims priority to Chinese patent application No. 202111132340.6, filed with the National Intellectual Property Administration of China on September 26, 2021, titled "METHOD FOR PREPARING LITHIUM IRON PHOSPHATE POSITIVE ELECTRODE MATERIAL, POSITIVE ELECTRODE PLATE AND LITHIUM ION BATTERY," the entire contents of which are incorporated herein by reference. field The present disclosure relates to the field of lithium-ion batteries, and more specifically, to a lithium iron phosphate positive electrode material, a positive electrode plate, and a method for manufacturing a lithium-ion battery. Lithium iron phosphate materials are widely used in power batteries due to their advantages, such as high structural stability, excellent safety performance, moderate operating voltage, and low cost. However, lithium iron phosphate has an obvious disadvantage of low compaction density (typically 2.1-2.3 g/ cm³ , rarely exceeding 2.6 g/ cm³ ), which hinders the application of this material due to the low specific capacity and energy density of batteries made from it. Figure 1 is a scanning electron microscope (SEM) image of the LFP-1 material used in Example 1; Figure 2 is an SEM image of the LFP-2 material used in Example 1. Exemplary embodiments of the present disclosure will be described below. It should be noted that a person skilled in the art may make several improvements and modifications without departing from the principles of the present disclosure, and that such improvements and modifications fall within the scope of protection of the present disclosure. The technical solutions of the present disclosure are described below in conjunction with several specific examples. Example 1 A method for manufacturing a lithium iron phosphate cathode material includes the following steps. 1) Prepare the first lithium iron phosphate material. a. Iron phosphate, a lithium source (especially Li₂CO₃ ) , and a carbon source (especially glucose monohydrate) are weighed according to a molar ratio of Li:Fe of 1.03:1. The amount of carbon source added can ensure that the carbon content in the first lithium iron phosphate material is 1.5 wt%. These raw materials are dispersed in deionized water and uniformly mixed to prepare a mixture slurry with a solid content of 50 wt%. b. The mixture slurry is ground. The D50 particle size of the material obtained after grinding is approximately 0.35 μm. Then, the ground slurry is spray-dried and granulated. The temperature at the inlet of the spray-drying equipment is 200 ℃ and the temperature at the outlet of the spray-drying equipment is 105 ℃. c. The granulated powder obtained by spray drying is sintered in a nitrogen atmosphere. In the sintering process, the sintering temperature T1 is 775 °C and the sintering time t1 is 9 h. Spherical lithium iron phosphate material LFP-1 (SEM image shown in Fig. 1) is obtained, and its particle diameter D50 is 4.80 μm. The LFP-1 material is fabricated into an anode plate (see the method described below in this example), and the maximum compressive density A is measured to be 2.04 g/ cm³ . 2) Prepare a secondary lithium iron phosphate material. The differences from the fabrication of LFP-1 are as follows. In the sintering process, the sintering holding temperature T2 is 793 °C and the sintering holding time t2 is 8.3 h. After sintering, additional jet crushing is performed to obtain the second lithium iron phosphate material LFP-2, which has an irregular shape with a particle diameter D50 of 1.02 μm (SEM image is shown in Fig. 2). The LFP-2 material is fabricated into an anode plate, and its maximum compressive density B is measured to be 2.55 g/ cm³ . 3) An anode material is obtained by mixing LFP-1 and LFP-2 in equal mass ratios. The suitable value of the maximum compressive density of the anode material, C = 2.8991 g/ cm³ , is obtained through calculation according to the previously mentioned expression C = 0.0847t 1 + 0.0196T 1 - 0.0095t 2 + 0.0261T 2 - 33.6716. The anode material is manufactured into an anode plate. The anode material is mixed with a binder (specifically polyvinylidene fluoride, PVDF) and conductive carbon black in a mass ratio of 90:5:5, an appropriate amount of N-methyl pyrrolidone pyrrole (NMP) is added, and the materials are uniformly mixed to obtain an anode slurry. The anode slurry is coated on one side of a carbon-coated aluminum foil, then dried, rolled, and punched to form a disc with a diameter of 15 mm to obtain an anode plate. The actual maximum compressive density of the anode plate is measured to be 2.88 g/ cm³ , which is substantially the same as the compressive density C of the anode material obtained through calculation according to the expression of the present disclosure. The preparation of the lithium-ion battery is as follows. A coin cell is asse