CN-122025626-A - Positive electrode material and lithium ion secondary battery

CN122025626ACN 122025626 ACN122025626 ACN 122025626ACN-122025626-A

Abstract

The invention relates to the technical field of batteries, in particular to an O2-phase lithium cobalt oxide positive electrode material and a lithium ion secondary battery comprising the O2-phase lithium cobalt oxide positive electrode material. The O2-phase lithium cobalt oxide positive electrode material comprises Al, ni, mn and Na elements, wherein the O2-phase lithium cobalt oxide positive electrode material contains an I characteristic peak at the position of 18.6+/-0.15 DEG in an X-ray diffraction spectrogram, lithium metal is used as a buckling power of a counter electrode, the O2-phase lithium cobalt oxide positive electrode material is charged to 4.6V, the O2-phase lithium cobalt oxide positive electrode material contains an II characteristic peak at the position of 17.8+/-0.15 DEG in the X-ray diffraction spectrogram, contains a III characteristic peak at the position of 18.2+/-0.15 DEG in the 2 theta, and contains an IV characteristic peak at the position of 19.2+/-0.15 DEG in the 2 theta. The lithium ion secondary battery has excellent cycle stability and rate capability under the high-voltage condition.

Inventors

TIAN LINYUAN
SHEN BENCHAO
JIA SHIKUI

Assignees

珠海冠宇电池股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260312

Claims (10)

1. The O2-phase lithium cobalt oxide positive electrode material is characterized in that the chemical formula of the O2-phase lithium cobalt oxide positive electrode material is Li x Na y Co z M 1 p M 2 q O 2 , wherein 0.85< x <1.05,0< Y <0.2,0.9< z <1,0.0001< p <0.05,0 is less than or equal to q <0.01, M 1 comprises Al, ni and Mn, and M 2 comprises at least one of Mg, ti, zr, nb, la, W and Y; The mass content C1 of Al in the O2-phase lithium cobalt oxide positive electrode material is 3500ppm-10500ppm, the mass content C2 of Ni is 3ppm-1400ppm, the mass content C3 of Mn is 2ppm-1500ppm, and the mass content C4 of Na is 250ppm-1000ppm; the O2-phase lithium cobalt oxide positive electrode material contains an I characteristic peak at a position of 18.6 degrees+/-0.15 degrees of 2 theta in an X-ray diffraction spectrogram; In the buckling process of taking lithium metal as a counter electrode, when the lithium metal is charged to 4.6V, the O2-phase lithium cobalt oxide positive electrode material contains a characteristic peak II at a position of 17.8+/-0.15 DEG of 2 theta, a characteristic peak III at a position of 18.2+/-0.15 DEG of 2 theta and a characteristic peak IV at a position of 19.2+/-0.15 DEG of 2 theta in an X-ray diffraction spectrogram.
2. The O2 phase lithium cobalt oxide positive electrode material according to claim 1, wherein C1 is 3500ppm to 9500ppm, preferably 4000ppm to 7000ppm; and/or, C2 is 3ppm to 400ppm; and/or C3 is 2ppm to 500ppm; And/or, C4 is 400ppm to 800ppm; And/or, in the buckling process of taking lithium metal as a counter electrode, when the lithium metal is charged to 4.6V, the diffraction angle 2 theta corresponding to the characteristic peak II and the characteristic peak IV is different by 1.4 degrees+/-0.15 degrees in an X-ray diffraction spectrogram of the O2-phase lithium cobalt oxide positive electrode material.
3. The O2-phase lithium cobalt oxide positive electrode material according to claim 1 or 2, wherein when the O2-phase lithium cobalt oxide positive electrode material uses lithium metal as a counter electrode, the O2-phase lithium cobalt oxide positive electrode material has a redox peak in a voltage interval of 3.7±0.05V, a peak intensity of Q1, a redox peak in a voltage interval of 4.5v±0.05V, a peak intensity of Q2, and a unit of mAh/g/V in a differential capacity curve of charge and discharge at a current of 0.1C; preferably, Q1> Q2.
4. The O2-phase lithium cobalt oxide positive electrode material according to claim 1 or 2, wherein the mass content of Na element in the O2-phase lithium cobalt oxide positive electrode material is a > b, wherein a is diluted aqua regia prepared by mixing deionized water and aqua regia according to a volume ratio of 1:1, 10mL of diluted aqua regia is taken to soak 100mg of the O2-phase lithium cobalt oxide positive electrode material for 1 hour at 80 ℃, and then the diluted aqua regia is filtered, the mass content of Na element obtained by inductively coupled plasma test of filtrate is taken; And/or the mass content of Ni element in the O2-phase lithium cobalt oxide positive electrode material meets the requirement of d > C, wherein C is diluted aqua regia prepared by mixing deionized water and aqua regia according to the volume ratio of 1:1, 10mL of diluted aqua regia is taken to soak 100mg of the O2-phase lithium cobalt oxide positive electrode material for 1 hour at 80 ℃, the diluted aqua regia is filtered, the mass content of Ni element obtained by the filtrate through an inductive coupling plasma test is taken, d is filter residue obtained by taking the diluted aqua regia to soak for 10 minutes at 350 ℃, and the filtrate is filtered, and the mass content of Ni element obtained by the filtrate through the inductive coupling plasma test is taken; And/or the mass content of Mn element in the O2-phase lithium cobalt oxide positive electrode material meets the requirement of f > e, wherein e is diluted aqua regia prepared by mixing deionized water and aqua regia according to the volume ratio of 1:1, 10mL of diluted aqua regia is taken to soak 100mg of the O2-phase lithium cobalt oxide positive electrode material for 1 hour at 80 ℃, filtration is carried out, the mass content of Mn element obtained by inductively coupled plasma test of filtrate is taken, f is filter residue obtained by taking the diluted aqua regia to soak, 10mL of aqua regia is adopted to soak for 10min at 350 ℃, filtration is carried out, and the mass content of Mn element obtained by inductively coupled plasma test of filtrate is taken; Preferably, a is 250ppm to 1200ppm, preferably 400ppm to 850ppm; preferably, b is 100ppm to 1000ppm, preferably 250ppm to 700ppm; preferably, c is from 0.3ppm to 850ppm, preferably from 0.3ppm to 250ppm; preferably d is 1.5ppm to 1400ppm, preferably 1.5ppm to 400ppm; preferably, e is 1ppm to 1400ppm, preferably 1ppm to 400ppm; preferably, f is from 2ppm to 1500ppm, preferably from 2ppm to 500ppm.
5. The O2-phase lithium cobalt oxide positive electrode material according to claim 1 or 2, wherein the valence state of Ni element in the O2-phase lithium cobalt oxide positive electrode material comprises +2 valence and +3 valence, the valence state of Mn element comprises +3 valence and +4 valence, and the atomic percentages of ions in different valence states in the O2-phase lithium cobalt oxide positive electrode material satisfy the following conditions ：Mn 4+ /Co 3+ >Ni 2+ /Co 3+ >Ni 3+ /Co 3+ >Mn 3+ /Co 3+ .
6. The O2-phase lithium cobalt oxide positive electrode material according to claim 1 or 2, wherein 10 sites are sequentially selected along the radial direction from the center to the surface of the O2-phase lithium cobalt oxide positive electrode material, the mass content of element Al on each site is C5 by using a point sweep of an energy spectrometer, the average value of the maximum value and the minimum value of the mass content of the element Al on the 10 sites is C6, and the C5 and the C6 satisfy the relation of I (C5-C6) I multiplied by 100%/C6 less than or equal to 10%; And/or, let w1=b+d+f, w2=a+c+e, wherein, w1/w2 is more than or equal to 0.2 and less than or equal to 1.5; preferably, the method comprises the steps of, w1 is more than or equal to 0.5 w2 is less than or equal to 1.2; And/or the mass content of Co element in the O2-phase lithium cobalt oxide positive electrode material is 1.1-8, preferably 2-6, wherein g is diluted aqua regia prepared by mixing deionized water and aqua regia according to the volume ratio of 1:1, 10mL of diluted aqua regia is taken to soak 100mg of the O2-phase lithium cobalt oxide positive electrode material for 1 hour at 80 ℃, the solution is filtered, the mass content of Co element obtained by inductively coupled plasma test of filtrate is taken, h is the mass content of Co element obtained by inductively coupled plasma test of filtrate, the filter residue obtained by soaking diluted aqua regia is taken, 10mL of aqua regia is taken to soak for 10min at 350 ℃, and the solution is filtered, and the mass content of Co element obtained by inductively coupled plasma test of filtrate is taken; And/or the mass content of Al element in the O2-phase lithium cobalt oxide positive electrode material is more than or equal to 0.6 and less than or equal to 2, preferably, 0.85 and less than or equal to 1.5, wherein j is the mass content of Al element obtained by soaking 100mg of the O2-phase lithium cobalt oxide positive electrode material for 1 hour at 80 ℃ by adopting deionized water and aqua regia according to the volume ratio of 1:1, filtering, taking the filtrate to obtain the mass content of Al element by inductive coupling plasma test, k is the filter residue obtained by taking the diluted aqua regia to soak, and filtering after soaking 10mL of aqua regia for 10 minutes at 350 ℃, and taking the mass content of Al element obtained by the filtrate by inductive coupling plasma test; preferably j is 1500ppm to 7000ppm; preferably, k is 1500ppm to 7000ppm; more preferably, let w3=b/(k+d+f), w4=a/(j+c+e), where, w4/w3 is more than or equal to 0.5 and less than or equal to 5; preferably, the method comprises the steps of, w4 is 0.5 +. w3 is less than or equal to 3.
7. The O2-phase lithium cobalt oxide positive electrode material according to claim 1 or 2, wherein the O2-phase lithium cobalt oxide positive electrode material further contains a P2 phase; and/or the morphology of the O2-phase lithium cobalt oxide positive electrode material comprises a sheet shape, wherein the sheet diameter d1 of the O2-phase lithium cobalt oxide positive electrode material along the long axis direction is 1-20 mu m, the sheet diameter d2 along the short axis direction is 0.2-10 mu m, and the thickness d3 of the sheet is 0.2-10 mu m.
8. A lithium ion secondary battery, which is characterized by comprising a positive plate, wherein the positive plate comprises a positive current collector and a positive active layer positioned on at least one side surface of the positive current collector, the positive active layer comprises a positive material, and the positive material comprises the O2 phase lithium cobalt oxide positive electrode material according to any one of claims 1-7; Preferably, the O3 phase lithium cobaltate cathode material includes at least one of Al, mg and Y elements; More preferably, the mass content of Mg element in the positive electrode active layer is 400ppm-1500ppm; More preferably, the mass content of the Y element in the positive electrode active layer is 400ppm to 1500ppm; Preferably, the charge cut-off voltage of the lithium ion secondary battery is more than or equal to 4.5V.
9. The lithium ion secondary battery of claim 8, wherein the lithium ion secondary battery further comprises a negative electrode sheet comprising a negative electrode current collector and a negative electrode active layer on at least one side surface of the negative electrode current collector, the negative electrode active layer comprising a silicon-carbon material comprising a porous carbon matrix and silicon particles in internal pores of the porous carbon matrix; Preferably, the mass content of silicon element in the negative electrode active layer is 3% -70%, more preferably 3% -50%, and even more preferably 3% -20%; Preferably, the anode active layer further comprises single-walled carbon nanotubes; More preferably, the diameter of the single-walled carbon nanotubes is 1nm to 10nm.
10. The lithium ion secondary battery of claim 8, wherein the lithium ion secondary battery further comprises an electrolyte solution comprising fluoroethylene carbonate; preferably, the mass content of fluoroethylene carbonate in the electrolyte is 5% -20%.

Description

Positive electrode material and lithium ion secondary battery Technical Field The invention relates to the technical field of batteries, in particular to an O2-phase lithium cobalt oxide positive electrode material and a lithium ion secondary battery comprising the O2-phase lithium cobalt oxide positive electrode material. Background The O2-phase lithium cobaltate has excellent structural stability and lithium ion diffusivity as an important positive electrode material for lithium batteries, and has been recently considered as an ideal candidate for the positive electrode material. However, as the energy density requirements of lithium ion batteries for portable electronic devices, electric vehicles and other consumer electronic devices are continuously increasing, the capacity exertion of O2 phase lithium cobaltate has been difficult to meet the current application requirements of lithium ion batteries. In order to improve the energy density of the lithium ion battery, the improvement of the charge cut-off voltage of the O2 phase lithium cobalt oxide positive electrode material is an effective solution, but with the continuous improvement of the charge voltage, for example, the charge cut-off voltage is improved to be more than 4.5V, the lithium removal degree of the O2 phase lithium cobalt oxide positive electrode material is deeper, the unit cell volume change is larger, irreversible phase change occurs, local distortion of crystal lattice and local stress concentration are caused, and finally the positive electrode active material is broken, so that the problems of rapid capacity attenuation, poor cycle stability and the like are caused. Therefore, it is necessary to improve the cycle stability of the positive electrode material under high voltage conditions. Disclosure of Invention The present invention has been made to overcome the above-mentioned problems occurring in the prior art, and an object of the present invention is to provide an O2-phase lithium cobalt oxide positive electrode material and a lithium ion secondary battery including the same. According to the invention, the lithium cobaltate positive electrode material is modified, so that gram capacity exertion and high-voltage resistance of the positive electrode material are effectively improved, and the cycle stability and rate capability of the battery under high voltage (for example, 4.5V and above) are improved. The first aspect of the invention provides an O2-phase lithium cobalt oxide positive electrode material, wherein the chemical formula of the O2-phase lithium cobalt oxide positive electrode material is Li xNayCozM1pM2qO2, 0.85< X <1.05,0< Y <0.2,0.9< z <1,0.0001< p <0.05, 0≤q <0.01, M 1 comprises at least one of Al, ni and Mn, M 2 comprises Mg, ti, zr, nb, la, W and Y, the mass content of Al in the O2-phase lithium cobalt oxide positive electrode material is 3500ppm-105 ppm, the mass content of Ni in C2 is 3ppm-1400ppm, the mass content of Mn in C3 is 2ppm-1500ppm, the mass content of Na in C4 is 250ppm-1000ppm, the O2-phase lithium cobalt oxide positive electrode material contains an I characteristic peak at 18.6 DEG + -0.15 DEG in an X-ray diffraction spectrum, the lithium metal as a buckling electrode, the O2-phase contains 4.6℃ in a positive electrode peak at 0.15 DEG to 3 DEG C2-0.15 DEG, and the O2-phase cobalt oxide positive electrode material contains a 3 DEG C2-15 DEG C2, the O2-phase is 2 DEG C2-3 and the positive electrode material contains a 2 DEG C2-3. In a second aspect, the invention provides a lithium ion secondary battery comprising the O2 phase lithium cobalt oxide cathode material according to the first aspect of the invention. Through the technical scheme, compared with the prior art, the invention has at least the following advantages: (1) The O2-phase lithium cobalt oxide anode material can keep better structural stability and higher gram capacity under the condition of high voltage (the charge cut-off voltage is more than or equal to 4.5V); (2) The lithium ion secondary battery has excellent cycle stability and rate capability. The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. Drawings FIG. 1 shows an X-ray diffraction pattern of an O2 phase lithium cobalt oxide positive electrode material in accordance with an embodiment of the present invention. FIG. 2 shows the differential capacity curve (dQ/dV) of an O2 phase lithium cobalt oxide positive electrode material in accordance with an embodiment of the present invention. Fig. 3 is a schematic structural diagram of an O2 phase lith