CN-115275171-B - Positive electrode active material and application thereof

CN115275171BCN 115275171 BCN115275171 BCN 115275171BCN-115275171-B

Abstract

The invention provides a positive electrode active material and application thereof. The positive electrode active material comprises matrix particles and a graphite coating layer, wherein the matrix particles comprise lithium metal oxide and the graphite coating layer covers at least part of the surfaces of the matrix particles, the lithium metal oxide has a structure shown in a formula 1, in an X-ray diffraction spectrum, the lithium metal oxide is a Cmca space group of a cubic crystal system and has 002 peaks with 2 theta of 17.9-18.1 degrees and 131 peaks with 2 theta of 67.0-67.5 degrees, li n‑y Na y Co 1‑a M a O 2 is shown in the formula 1, n is more than or equal to 0.6 and less than or equal to 0.8, y is more than or equal to 0 and less than or equal to 0.05, and a is more than or equal to 0.2, wherein M is a doping element. The special composition and crystal phase structure of the positive electrode active material are favorable for improving the specific capacity and cycle performance of the battery, and the battery can still be excellent in performance under high-pressure conditions.

Inventors

Zeng Jiajiang
XIA DINGGUO
LI SULI

Assignees

珠海冠宇电池股份有限公司

Dates

Publication Date: 20260505
Application Date: 20220902

Claims (3)

1. The positive plate is characterized by comprising a current collector, a safety layer and a positive electrode active layer, wherein the safety layer is arranged between the current collector and the positive electrode active layer in an interlayer mode, the positive electrode active layer comprises a positive electrode active material, the positive electrode active material is composed of matrix particles comprising lithium metal oxide and a reduced graphene oxide coating layer covering at least part of the surfaces of the matrix particles, and in a Raman spectrum diagram, the peak intensity IG of the positive electrode active material at a wavelength 1560+/-30 cm -1 and the peak intensity ID of the positive electrode active material at a wavelength 1360+/-30 cm -1 are 80% -ID/IG-90%; The lithium metal oxide has a structure represented by formula 2; In an X-ray diffraction spectrum, the lithium metal oxide is a Cmca space group of a cubic system, and has 002 peaks with 2 theta of 17.9-18.1 degrees and 131 peaks with 2 theta of 67.0-67.5 degrees; Li n-y Na y Co 1-a1-a2 M1 a1 M2 a2 O 2 type 2 In the formula 2, the components are mixed, n is more than or equal to 0.6 and less than or equal to 0.8,0< y 0.05 or more, 0< a1 or less than 0.1 or 0 a2 is more than or equal to 0.1,0< a1/1-a2<0.1; wherein M1 is selected from at least one of Te, W, al, B, P and K, M2 is a doping element different from M1; Based on the total mass of the positive electrode active material, the mass percentage W of the reduced graphene oxide coating layer is 0<W-1%; When the cut-off voltage of the positive electrode active material is 3.0-3.6V and the SOC is zero, n is more than or equal to 0.7 and less than or equal to 1.0; the median particle diameter of the positive electrode active material is 12-20 mu m.
2. A lithium ion battery comprising the positive electrode sheet of claim 1.
3. The lithium ion battery of claim 2, wherein the negative electrode sheet in the lithium ion battery is a lithium-containing negative electrode sheet.

Description

Positive electrode active material and application thereof Technical Field The invention relates to a pole piece material, in particular to a positive electrode active material and application thereof, and belongs to the technical field of secondary batteries. Background With the development and progress of lithium ion battery technology, the capacity of lithium ion batteries is increasingly required. In the composition of the lithium ion battery, the high and low of the positive electrode active material capacity plays a vital role in the capacity of the lithium ion battery. In order to increase the capacity of lithium ion batteries, the most commonly used method is to increase the charge-discharge voltage. However, with the increase of voltage, the positive electrode active material has a collapse phenomenon of a crystal structure, so that a series of problems such as rapid capacity decay and great reduction of cycle performance of the battery are caused. Therefore, developing a lithium ion battery positive electrode active material with high specific capacity and good cycle performance is a technical problem to be solved in the field. Disclosure of Invention The invention provides a positive electrode active material, which has a special composition and a crystal phase structure, is favorable for improving the specific capacity and the cycle performance of a battery, and can still make the battery perform excellent especially under high pressure conditions. The invention provides a positive plate which comprises the positive active material, thereby being beneficial to improving the relevant electrical performance of a battery. The invention also provides a lithium ion battery which comprises the positive plate, so that the lithium ion battery has excellent performance in specific capacity and cycle performance. The invention provides a positive electrode active material, wherein the positive electrode active material is composed of matrix particles comprising lithium metal oxide and a graphite coating layer covering at least part of the surfaces of the matrix particles; The lithium metal oxide has a structure represented by formula 1; In an X-ray diffraction spectrum, the lithium metal oxide is a Cmca space group of a cubic system, and has 002 peaks with 2 theta of 17.9-18.1 degrees and 131 peaks with 2 theta of 67.0-67.5 degrees; Li n-yNayCo1-aMaO2 type 1 In the formula 1, the components are mixed, n is more than or equal to 0.6 and less than or equal to 0.8, y is more than or equal to 0 and less than or equal to 0 0.05, a is more than or equal to 0 and less than or equal to 0.2; wherein M is a doping element. The positive electrode active material as described above, wherein the lithium metal oxide has a structure represented by formula 2; Li n-yNayCo1-a1-a2M1a1M2a2O2 type 2 In the formula 2, the components are mixed, a1 is more than or equal to 0 and less than or equal to 0.1, and a2 is more than or equal to 0 and less than or equal to 2 a1+a2=a, which is less than or equal to 0.1; Wherein M1 is at least one selected from Te, W, al, B, P and K, and M2 is a doping element different from M1. The positive electrode active material as described above, wherein the graphite coating layer has a mass percentage W of 0<W≤1% based on the weight of the positive electrode active material. The positive electrode active material as described above, wherein the graphite coating layer is a reduced graphene oxide coating layer. In the positive electrode active material, in a Raman spectrum, the peak intensity I G of the lithium metal oxide at the wavelength of 1560+/-30 cm -1 and the peak intensity I D of the lithium metal oxide at the wavelength of 1360+/-30 cm -1 satisfy that I D/IG is more than or equal to 68%. The positive electrode active material is characterized in that when the cutoff voltage of the positive electrode active material is 3.0-3.6V and the SOC is zero, n is more than or equal to 0.7 and less than or equal to 1.0. The positive electrode active material, wherein the median particle diameter of the positive electrode active material is 12-20 mu m. The invention provides a positive plate, wherein the positive plate comprises the positive active material. The positive plate, wherein the positive plate comprises a current collector, a safety layer and a positive active layer; the safety layer is clamped between the current collector and the positive electrode active layer, and the positive electrode active layer comprises the positive electrode active material. The invention provides a lithium ion battery, wherein the lithium ion battery comprises the positive plate. The lithium ion battery, wherein the negative plate in the lithium ion battery is a lithium-containing negative plate. The positive electrode active material has a special crystal phase structure and chemical composition, after the positive electrode active material is applied to a battery, the cycle performance and gram capacity of the b