CN-115295789-B - Positive electrode active material and application thereof

CN115295789BCN 115295789 BCN115295789 BCN 115295789BCN-115295789-B

Abstract

The invention provides a positive electrode active material and application thereof, wherein the positive electrode active material comprises a lithium metal oxide shown in a formula 1 or a formula 2, in an X-ray diffraction pattern, 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, wherein M1 is at least one selected from Te, W, al, B, P and K in the formula 1 and the formula 2, and M2 is a doping element different from M1. The positive electrode active material is beneficial to improving the cycle performance and specific capacity of the lithium ion battery.

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 (4)

1. The lithium ion battery is characterized by comprising a positive plate and a negative plate, wherein the positive plate comprises a positive active material, the positive active material comprises a lithium metal oxide shown in formula 1 or formula 2, and the positive active material comprises an inner core comprising the lithium metal oxide and a coating layer covering at least part of the surface of the inner core, and the coating layer is made of a carbon-containing compound and a fast ion conductor material; 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 n1-y1 Na y1 Co 1-a1-b1 M1 b1 M2 a1 O 2 type 1 Li n2-y2-b2 Na y2 Co 1-a2 M1 b2 M2 a2 O 2 type 2 In the formula 1, the components are mixed, n1 is more than or equal to 0.6 and less than or equal to 0.8,0< y1 not less than 0.05, not less than 0 and not more than 1 a 0.1,0< b1≤0.1, 0< b1/1-a1-b1<0.1; In the formula 2, the components are mixed, n2 is more than or equal to 0.6 and less than or equal to 0.8, y2 is more than or equal to 0 and less than or equal to 0.05,0 a2 is more than or equal to 0.1, b2 is more than or equal to 0 and less than or equal to 0.02, Wherein M1 is selected from at least one of Te, W, al, B, P and K, M2 is a doping element different from M1, M1 in formula 1 contains B atoms, wherein the intercalation of the B atoms replaces Co atoms in the lithium metal oxide; the median particle diameter of the positive electrode active material is 12-20 mu m; the peak intensity of the 002 peak is I1, the peak intensity of the 131 peak is I2, and I1/I2 is more than or equal to 4; The first-stage discharge capacity of the positive electrode active material is more than or equal to 9% of C1/C0, and the second-stage discharge capacity is more than or equal to 25% of C2/C0; Wherein C0 is the discharge capacity of the half cell containing the positive electrode active material when the half cell is subjected to discharge treatment at a voltage of 3.0-4.55V, wherein in the discharge treatment, the capacity of the half cell discharged from an initial discharge voltage to 4.4V is defined as C1, and the capacity of the half cell discharged from 3.8V to 3.7V is defined as C2.
2. The lithium ion battery of claim 1, wherein in formula 2, M1 is K.
3. The lithium ion battery according to claim 1 or 2, wherein when the cutoff voltage of the positive electrode active material is 3.0-3.6 v and the SOC is zero, n1 is 0.7-1.0,0.7-n 2 is 1.0.
4. The lithium ion battery of claim 1, wherein the negative electrode sheet 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 present invention provides a positive electrode active material including a lithium metal oxide represented by formula 1 or 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 n1-y1Nay1Co1-a1-b1M1b1M2a1O2 type 1 Li n2-y2-b2Nay2Co1-a2M1b2M2a2O2 type 2 In the formula 1, the components are mixed, n1 is more than or equal to 0.6 and less than or equal to 0.8,0< y1 not less than 0.05, not less than 0 and not more than 1 a 0.1,0< b1≤0.1, 0< b1/1-a1-b1<0.1; In the formula 2, the components are mixed, n2 is more than or equal to 0.6 and less than or equal to 0.8, y2 is more than or equal to 0 and less than or equal to 0.05,0 a2 is more than or equal to 0.1, b2 is more than or equal to 0 and less than or equal to 0.02, Wherein M1 is selected from at least one of Te, W, al, B, P and K, and M2 is doping element. The positive electrode active material as described above, wherein in formula 1, M1 is selected from one of Al, W, and/or Te, B, and/or P; In formula 2, M1 is K. The positive electrode active material as described above, wherein the positive electrode active material is composed of a core including the lithium metal oxide and a coating layer covering at least a part of the surface of the core. The positive electrode active material is 0.7-1 and n 2-1.0 when the cut-off voltage is 3.0-3.6V and the SOC is zero. The positive electrode active material, wherein the median particle diameter of the positive electrode active material is 12-20 mu m. The positive electrode active material as described above, wherein, The first-stage discharge capacity of the positive electrode active material is more than or equal to 9% of C1/C0, and the second-stage discharge capacity is more than or equal to 25% of C2/C0; Wherein C0 is the discharge capacity of the half cell containing the positive electrode active material when the half cell is subjected to discharge treatment at a voltage of 3.0-4.55V, wherein in the discharge treatment, the capacity of the half cell discharged from an initial discharge voltage to 4.4V is defined as C1, and the capacity of the half cell discharged from 3.8V to 3.7V is defined as C2. The positive electrode active material as described above, wherein the 002 peak has a peak intensity of I1, the 131 peak has a peak intensity of I2, and I1/I2 is not less than 4. The invention provides a positive electrode sheet comprising the positive electrode active material described in any one of the above. The invention provides a lithium ion battery, which 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 battery are remarkably improved, and even under the high-pressure condition of 4.5V and above, the battery using the positiv