U.S. patent application number 16/249888 was filed with the patent office on 2019-08-08 for positive active material and lithium-ion battery.
The applicant listed for this patent is Ningde Amperex Technology Limited. Invention is credited to Kefei Wang, Qiao Zeng.
Application Number | 20190245199 16/249888 |
Document ID | / |
Family ID | 67475763 |
Filed Date | 2019-08-08 |
United States Patent
Application |
20190245199 |
Kind Code |
A1 |
Zeng; Qiao ; et al. |
August 8, 2019 |
POSITIVE ACTIVE MATERIAL AND LITHIUM-ION BATTERY
Abstract
The present application provides a positive active material, a
positive electrode and a lithium-ion battery. The positive active
material comprising a first particle and a second particle, wherein
the first particle has a chemical formula of
Li.sub.eCo.sub.gM.sub.1-gO.sub.2-i, and the second particle has a
chemical formula of Li.sub.fCo.sub.hN.sub.1-hO.sub.2-j, the element
M is at least two selected from a group consisting of Ni, Mn, Al,
Mg, Ti, La, Y and Zr, the element N is at least one selected from a
group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and
0.8.ltoreq.e.ltoreq.1.2, 0<g<1, -0.1.ltoreq.i.ltoreq.0.2,
0.8.ltoreq.f.ltoreq.1.2, 0<h<1, -0.1.ltoreq.j.ltoreq.0.2, the
number of types of the element M in the first particle is greater
than the number of types of the element N in the second particles.
The positive active material of the present application has a good
stability and can improve the capacity retention rate of the
lithium-ion battery.
Inventors: |
Zeng; Qiao; (Ningde, CN)
; Wang; Kefei; (Ningde, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ningde Amperex Technology Limited |
Ningde |
|
CN |
|
|
Family ID: |
67475763 |
Appl. No.: |
16/249888 |
Filed: |
January 16, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/CN2018/122758 |
Dec 21, 2018 |
|
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16249888 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 4/131 20130101;
H01M 2004/028 20130101; C01P 2004/51 20130101; C01P 2004/03
20130101; C01G 51/00 20130101; H01M 4/505 20130101; C01G 51/42
20130101; C01G 51/50 20130101; H01M 4/364 20130101; C01G 51/40
20130101; H01M 2004/021 20130101; C01G 53/50 20130101; C01P 2006/40
20130101; H01M 4/525 20130101; C01P 2004/61 20130101; H01M 10/0525
20130101 |
International
Class: |
H01M 4/36 20060101
H01M004/36; H01M 4/525 20060101 H01M004/525; H01M 4/505 20060101
H01M004/505; H01M 10/0525 20060101 H01M010/0525 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2018 |
CN |
201810123144.4 |
Jul 16, 2018 |
CN |
201810779137.X |
Claims
1. A positive active material, comprising a first particle and a
second particle, wherein the first particle has a chemical formula
of Li.sub.eCo.sub.gM.sub.1-gO.sub.2-i, and the second particle has
a chemical formula of Li.sub.fCo.sub.hN.sub.1-hO.sub.2-j, the
element M is at least two selected from a group consisting of Ni,
Mn, Al, Mg, Ti, La, Y and Zr, the element N is at least one
selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and
Zr, and 0.8.ltoreq.e.ltoreq.1.2, 0<g<1,
-0.1.ltoreq.i.ltoreq.0.2, 0.8.ltoreq.f.ltoreq.1.2, 0<h<1,
-0.1.ltoreq.j.ltoreq.0.2, the number of types of the element M in
the first particle is greater than the number of types of the
element N in the second particles.
2. The positive active material according to claim 1, wherein the
first particle has a chemical formula of
Li.sub.nCo.sub.xM.sub.1-xO.sub.2-y, and the second particle has a
chemical formula of Li.sub.nCo.sub.xN.sub.1-xO.sub.2-y, and
0.8.ltoreq.n.ltoreq.1.2, 0<x<1, -0.1.ltoreq.y.ltoreq.0.2.
3. The positive active material according to claim 1, wherein the
particle diameter of the first particle is smaller than the
particle diameter of the second particle.
4. The positive active material according to claim 3, wherein the
particle diameter of the first particle is smaller than Dv50 of the
positive active material, and the particle diameter of the second
particle is larger than Dv50 of the positive active material.
5. The positive active material according to claim 1, wherein each
of the elements M is contained in the first particle in an amount
of more than 200 ppm, and each of the elements N is contained in
the second particle in an amount of more than 200 ppm.
6. The positive active material according to claim 1, wherein the
positive active material meets the following formula (1):
(a/b)/(c/d)>1 formula (1) a represents the total mass of the
element M in the first particle; b represents the mass of the
element Co in the first particle; c represents the total mass of
the element N in the second particle; d represents the mass of the
element Co in the second particle.
7. The positive active material according to claim 1, wherein the
positive active material meets the following formula (2):
(A/B)/(C/D)>1 formula (2) A represents the total molar amount of
the element M in the first particle; B represents the molar amount
of the element Co in the first particle; C represents the total
molar amount of the element N in the second particle; D represents
the molar amount of the element Co in the second particle.
8. The positive active material according to claim 6, wherein the
positive active material has a value of (a/b)/(c/d) of 1.3 to
10.
9. The positive active material according to claim 1, wherein the
volume-based particle size distribution curve of the positive
active material comprises a first peak and a second peak.
10. The positive active material according to claim 9, wherein the
peak height of the second peak is greater than the peak height of
the first peak.
11. The positive active material according to claim 1, wherein the
particle diameter of the positive active material meets the
following formula (3): (Dv90-Dv50)-(Dv50-Dv10).ltoreq.2.5 formula
(3).
12. A positive electrode, wherein comprising a positive active
material, wherein the positive active material comprising a first
particle and a second particle, wherein the first particle has a
chemical formula of Li.sub.eCo.sub.gM.sub.1-gO.sub.2-i, and the
second particle has a chemical formula of
Li.sub.fCo.sub.hN.sub.1-hO.sub.2-j, the element M is at least two
selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and
Zr, the element N is at least one selected from a group consisting
of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and 0.8.ltoreq.e.ltoreq.1.2,
0<g<1, -0.1.ltoreq.i.ltoreq.0.2, 0.8.ltoreq.f.ltoreq.1.2,
0<h<1, -0.1.ltoreq.j.ltoreq.0.2, the number of types of the
element M in the first particle is greater than the number of types
of the element N in the second particles.
13. The positive electrode according to claim 12, wherein the
particle diameter of the first particle is smaller than the
particle diameter of the second particle.
14. The positive electrode according to claim 13, wherein the
particle diameter of the first particle is smaller than Dv50 of the
positive active material, and the particle diameter of the second
particle is larger than Dv50 of the positive active material.
15. The positive electrode according to claim 12, wherein each of
the elements M is contained in the first particle in an amount of
more than 200 ppm, and each of the elements N is contained in the
second particle in an amount of more than 200 ppm.
16. The positive electrode according to claim 12, wherein the
positive active material meets the following formula (1):
(a/b)/(c/d)>1 formula (1) a represents the total mass of the
element M in the first particle; b represents the mass of the
element Co in the first particle; c represents the total mass of
the element N in the second particle; d represents the mass of the
element Co in the second particle.
17. The positive electrode according to claim 12, wherein the
positive active material meets the following formula (2):
(A/B)/(C/D)>1 formula (2) A represents the total molar amount of
the element M in the first particle; B represents the molar amount
of the element Co in the first particle; C represents the total
molar amount of the element N in the second particle; D represents
the molar amount of the element Co in the second particle.
18. A lithium-ion battery, wherein comprising a positive electrode
with a positive active material, wherein the positive active
material comprising a first particle and a second particle, wherein
the first particle has a chemical formula of
Li.sub.eCo.sub.gM.sub.1-gO.sub.2-i, and the second particle has a
chemical formula of Li.sub.fCo.sub.hN.sub.1-hO.sub.2-j, the element
M is at least two selected from a group consisting of Ni, Mn, Al,
Mg, Ti, La, Y and Zr, the element N is at least one selected from a
group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and
0.8.ltoreq.e.ltoreq.1.2, 0<g<1, -0.1.ltoreq.i.ltoreq.0.2,
0.8.ltoreq.f.ltoreq.1.2, 0<h<1, -0.1.ltoreq.j.ltoreq.0.2, the
number of types of the element M in the first particle is greater
than the number of types of the element N in the second
particles.
19. The lithium-ion battery according to claim 18, wherein the
compact density of the positive electrode is g/cm.sup.3.
20. The lithium-ion battery according to claim 18, wherein the
particle diameter of the first particle is smaller than the
particle diameter of the second particle.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application of PCT
application No. PCT/CN2018/122758 filed on Dec. 21, 2018, which
claims priority to and benefits of Chinese Patent Application
Serial No. 201810779137.X, filed with China National Intellectual
Property Administration on Jul. 16, 2018, and Chinese Patent
Application Serial No. 201810123144.4, filed with China National
Intellectual Property Administration on Feb. 7, 2018, the entire
contents of which are incorporated herein by reference.
FIELD OF THE APPLICATION
[0002] The examples of the present application relate to the field
of battery, in particular, to a positive active material and a
lithium-ion battery.
BACKGROUND OF THE APPLICATION
[0003] Due to its long service life and high energy density, the
lithium-ion battery is widely used in portable electronic products
such as mobile phones, notebook computers, and digital cameras. It
also has good application prospects in electric vehicles and other
fields. With the expansion of its application range, higher
requirements has also been put forward for the performance of the
lithium-ion battery, in particular, with the popularization of
smart phones, higher requirements has been put forward for the
energy density of the lithium-ion battery.
[0004] However, when the energy density of the lithium-ion battery
is increased, the service life of the lithium-ion battery is
decreased. For this reason, there is an urgent need for a technical
solution for improving the energy density of the lithium-ion
battery without reducing its service life.
SUMMARY OF THE APPLICATION
[0005] In order to solve the defects in the prior art, examples of
the present application provide a positive active material, which
stabilizes the first particles by adjusting the type and content of
the doping elements in the first particle and the second particle
so that the discharge capacity retention rate at 500 cycles of
lithium-ion battery is improved (discharge capacity retention rate
at 500 cycles: ratio of discharge capacity at 500 cycles to initial
discharge capacity).
[0006] According to the first aspect of the present application, a
positive active material is provided, wherein the positive active
material comprising a first particle and a second particle, wherein
the first particle has a chemical formula of
Li.sub.eCo.sub.gM.sub.1-gO.sub.2-i, and the second particle has a
chemical formula of Li.sub.fCo.sub.hN.sub.1-hO.sub.2-j, the element
M is at least two selected from a group consisting of Ni, Mn, Al,
Mg, Ti, La, Y and Zr, the element N is at least one selected from a
group consisting of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and
0.8.ltoreq.e.ltoreq.1.2, 0<g<1, -0.1.ltoreq.i.ltoreq.0.2,
0.8.ltoreq.f.ltoreq.1.2, 0<h<1, -0.1.ltoreq.j.ltoreq.0.2, the
number of types of the element M in the first particle is greater
than the number of types of the element N in the second
particles.
[0007] In above positive active material, the first particle has a
chemical formula of Li.sub.nCo.sub.xM.sub.1-xO.sub.2-y, and the
second particle has a chemical formula of
Li.sub.nCo.sub.xN.sub.1-xO.sub.2-y, and 0.8.ltoreq.n.ltoreq.1.2,
0<x<1, -0.1.ltoreq.y.ltoreq.0.2
[0008] In above positive active material, the particle diameter of
the first particle is smaller than the particle diameter of the
second particle.
[0009] In above positive active material, the particle diameter of
the first particle is smaller than Dv50 of the positive active
material, and the particle diameter of the second particle is
larger than Dv50 of the positive active material.
[0010] In above positive active material, wherein each of the
elements M is contained in the first particle in an amount of more
than 200 ppm and each of the elements N is contained in the second
particle in an amount of more than 200 ppm.
[0011] In above positive active material, the positive active
material meets the following equation (1):
(a/b)/(c/d)>1 equation (1)
[0012] a represents the total mass of the element M in the first
particle;
[0013] b represents the mass of the element Co in the first
particle;
[0014] c represents the total mass of the element N in the second
particle;
[0015] d represents the mass of the element Co in the second
particle.
[0016] In above positive active material, the positive active
material meets the following equation (2):
(A/B)/(C/D)>1 equation (2)
[0017] A represents the total molar amount of the element M in the
first particle;
[0018] B represents the molar amount of the element Co in the first
particle;
[0019] C represents the total molar amount of the element N in the
second particle;
[0020] D represents the molar amount of the element Co in the
second particle.
[0021] In above positive active material, the positive active
material has a value of (a/b)/(c/d) of 1.3 to 10.
[0022] In above positive active material, the volume-based particle
size distribution curve of the positive active material comprises a
first peak and a second peak.
[0023] In above positive active material, the peak height of the
second peak is greater than the peak height of the first peak.
[0024] In above positive active material, the particle diameter of
the positive active material meets the following equation (3):
(Dv90-Dv50)-(Dv50-Dv10).ltoreq.2.5 equation (3)
[0025] According to the second aspect of the present application, a
positive electrode is further provided, wherein the positive
electrode comprises the positive active material according to the
first aspect of the present application.
[0026] In above positive electrode, the compact density of the
positive electrode after pressing is .gtoreq.3.9 g/cm.sup.3.
[0027] According to the third aspect of the present application, a
lithium-ion battery is further provided, wherein it comprises the
positive electrode according to the second aspect of the present
application.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0028] FIG. 1A shows a scanning electron microscope (SEM) view of
the positive active material according to Example 1 of the present
application.
[0029] FIG. 1B shows a scanning electron microscope (SEM) view of
the positive active material according to Comparative Example
6.
[0030] FIG. 2 shows a particle size distribution curve of the
positive active material according to Example 1 of the present
application and Comparative Example 6.
[0031] FIG. 3 shows the results of testing thermal stability of
electrode for the positive active material according to Example 1
of the present application and Comparative Example 6.
DETAILED DESCRIPTION OF THE PREFERRED EXAMPLES
[0032] The exemplary examples are described in sufficient detail
below, but these exemplary examples may be implemented in various
ways and should not be construed as being limited to the examples
set forth herein. Rather, these examples are provided so that the
present application will be thorough and complete and the scope of
the present application is fully conveyed to those skilled in the
art.
[0033] In the present application, a positive active material is
provided, the positive active material comprising a first particle
and a second particle, wherein the first particle has a chemical
formula of Li.sub.eCo.sub.gM.sub.1-gO.sub.2-i, and the second
particle has a chemical formula of
Li.sub.fCo.sub.hN.sub.1-hO.sub.2-j, the element M is at least two
selected from a group consisting of Ni, Mn, Al, Mg, Ti, La, Y and
Zr, the element N is at least one selected from a group consisting
of Ni, Mn, Al, Mg, Ti, La, Y and Zr, and 0.8.ltoreq.e.ltoreq.1.2,
0<g<1, -0.1.ltoreq.i.ltoreq.0.2, 0<h<1,
-0.1.ltoreq.j.ltoreq.0.2, the number of types of the element M in
the first particle is greater than the number of types of the
element N in the second particles.
[0034] In some examples of the present application, the first
particle has a chemical formula of
Li.sub.nCo.sub.xM.sub.1-xO.sub.2-y, and the second particle has a
chemical formula of Li.sub.nCo.sub.xN.sub.1-xO.sub.2-y, and
0.8.ltoreq.n.ltoreq.1.2, 0<x<1, -0.1.ltoreq.y.ltoreq.0.2.
[0035] The particle diameter of the first particle in the positive
active material is smaller than that of the second particle, and
the blending of the particles of different sizes may increase the
compact density of the positive electrode, thereby improving the
energy density of the lithium-ion battery. However, the first
particle has a small particle diameter, a large specific surface
area, a strong activity, and is liable to cause side reactions with
the electrolyte, so that the stability of the entire positive
active material is lowered and the service life of the lithium-ion
battery is shortened. In some examples of the present application,
the number of types of the element M in the first particle is
greater than the number of types of the element M in the second
particles, so the first particle having a smaller particle diameter
may be effectively stabilized and the side reaction of the first
particle with the electrolyte may be suppressed so that the service
life of the lithium-ion battery is improved.
[0036] In some examples of the present application, each of the
elements M is contained in the first particle in an amount of more
than 200 ppm and each of the elements N is contained in the second
particle in an amount of more than 200 ppm. The content of the M
element and the N element may be detected by ICP (Inductively
Coupled Plasma Spectrometer). If the content of each element in the
elements M is less than 200 ppm, the element M may not function to
stabilize the first particle and if the content of each element in
the elements N is less than 200 ppm, the element N may not function
to stabilize the second particle.
[0037] In some examples of the present application, the positive
active material meets the following equation (1):
(a/b)/(c/d)>1 equation (1)
[0038] wherein a represents the total mass of the element M in the
first particle; b represents the mass of the element Co in the
first particle; c represents the total mass of the element N in the
second particle; d represents the mass of the element Co in the
second particle.
[0039] In some examples of the present application, the positive
active material meets the following equation (2):
(A/B)/(C/D)>1 equation (2)
[0040] wherein A represents the total molar amount of the element M
in the first particle; B represents the molar amount of the element
Co in the first particle; C represents the total molar amount of
the element N in the second particle; D represents the molar amount
of the element Co in the second particle.
[0041] The first particle and the second particle meeting the
equation (1) or the equation (2) allows the element M to fully
exert its effect. The content of the element M corresponding to the
element Co of per unit in the first particle with a smaller
particle diameter is larger than the content of the element N
corresponding to the element Co of per unit in the second particle
with a larger particle diameter. The smaller the particle diameter
of the particle, the larger the specific surface area and the
stronger the activity. So in order to achieve the purpose of
stabilizing the first particle having a smaller particle diameter,
more doping or coating of the element M is required for the first
particle so as to reduce side reactions of the first particle with
the electrolyte, making the first particle more stable. Thereby,
the capacity retention rate of the lithium-ion battery is improved,
while the second particle having a larger particle diameter
requires a relatively small amount of the element N to achieve a
stable effect.
[0042] In some examples of the present application, the positive
active material has a value of (a/b)/(c/d) of 1.3 to 10. In order
to make the first particle more stable without reducing the content
of the host material in the positive active material, the content
of the element M and the element N in the particles of the positive
active material should not be too low or too high. When the content
of the element M in the first particle and the content of the
element N in the second particle meet (a/b)/(c/d) of 1.3 to 10, a
balance may be achieved, and at this time, the comprehensive
performance of the lithium-ion battery is good.
[0043] In some examples of the present application, the
volume-based particle size distribution curve of the positive
active material comprises a first peak and a second peak; the peak
height of the second peak is greater than the peak height of the
first peak. The positive active material having such a particle
size distribution curve indicates that the particles are
concentrated near the particle diameters corresponding to the first
peak and the second peak. That is to say, there are many particles
in the vicinity of the corresponding particle diameters of the
first peak and the second peak, and the particle diameter
corresponding to the first peak and the particle diameter
corresponding to the second peak are different with one being large
and another one being small; and after two particles are mixed, the
particles with smaller particle diameter occupy the gap between the
particles with larger particle diameter, thereby increasing the
compact density of the positive electrode so as to increase the
energy density of the lithium-ion battery.
[0044] In some examples of the present application, the particle
diameter of the positive active material meets the following
equation (3):
(Dv90-Dv50)-(Dv50-Dv10).ltoreq.2.5 equation (3)
[0045] Dv90 refers to a particle diameter reaching a volume
accumulation of 90% from the small particle diameter side in the
volume-based particle size distribution. Dv50 refers to a particle
diameter reaching a volume accumulation of 50% from the small
particle diameter side in the volume-based particle size
distribution. Dv10 refers to a particle diameter reaching a volume
accumulation of 10% from the small particle diameter side in the
volume-based particle size distribution.
[0046] The positive active material meeting the equation (3) may
increase the compact density of the positive electrode, thereby
increasing the energy density of the lithium-ion battery.
[0047] The present application also provides a positive electrode
comprising the above positive active material, and a compact
density of the positive electrode after pressing is .gtoreq.3.9
g/cm.sup.3.
[0048] The present application also provides a lithium-ion battery
comprising the above positive electrode, the lithium-ion battery
further comprising a negative electrode containing a negative
active material layer, an electrolyte, and a separator between the
positive electrode and the negative electrode. The positive
electrode comprises a positive active material layer and a positive
electrode current collector. The positive electrode current
collector may be an aluminum foil and a nickel foil. The negative
electrode comprises a negative active material layer and a negative
electrode current collector. The negative electrode current
collector may be a copper foil or a nickel foil.
[0049] The negative electrode comprises a negative electrode
material capable of intercalation/deintercalation of lithium
(hereinafter, sometimes referred to as "negative electrode material
capable of intercalation/deintercalation of lithium"). Examples of
the negative electrode material capable of
intercalation/deintercalation of lithium may comprise carbon
materials, metal compounds, oxides, sulfides, nitrides of lithium
such as LiN.sub.3, lithium metal, metals which form alloys together
with lithium and polymer materials.
[0050] Examples of carbon materials may comprise low graphitized
carbon, easily graphitizable carbon, artificial graphite, natural
graphite, mesocarbon microbeads, soft carbon, hard carbon,
pyrolytic carbon, coke, vitreous carbon, organic polymer compound
sintered body, carbon fiber and activated carbon. Among them, coke
may comprise pitch coke, needle coke, and petroleum coke. The
organic polymer compound sintered body refers to a material
obtained by calcining a polymer material such as a phenol plastic
or a furan resin at a suitable temperature for carbonizing, and
some of these materials are classified into low graphitized carbon
or easily graphitizable carbon. Examples of the polymer material
may comprise polyacetylene and polypyrrole.
[0051] Further, in the negative electrode material capable of
intercalation/deintercalation of lithium, a material whose charging
and discharging voltages are close to the charging and discharging
voltages of lithium metal is selected. This is because the lower
the charging and discharging voltage of the negative electrode
material, the easier for the battery to have a higher energy
density. Among them, the negative electrode material may be
selected from carbon materials because their crystal structures are
only slightly changed upon charging and discharging, and therefore,
good cycle characteristics as well as large charge and discharge
capacities may be obtained. In particular, graphite may be selected
because it gives a large electrochemical equivalent and a high
energy density.
[0052] In addition, the negative electrode material capable of
intercalation/deintercalation of lithium may comprise elemental
lithium metal, metal elements and semimetal elements capable of
forming an alloy together with lithium, and alloys and compounds
comprising such metal elements and semimetal elements. In
particular, they are used together with carbon materials because in
this case, good cycle characteristics as well as high energy
density may be obtained. In addition to alloys comprising two or
more metal elements, the alloys used herein also comprise alloys
comprising one or more metal elements and one or more semi-metal
elements. The alloy may be in the form of a solid solution, a
eutectic crystal (eutectic mixture), an intermetallic compound, and
a mixture thereof.
[0053] Examples of the metal element and the semi-metal element may
comprise tin (Sn), lead (Pb), aluminum (Al), indium (In), silicon
(Si), zinc (Zn), antimony (Sb), bismuth (Bi), Cadmium (Cd),
magnesium (Mg), boron (B), gallium (Ga), germanium (Ge), arsenic
(As), silver (Ag), zirconium (Zr), yttrium (Y), and hafnium (Hf).
Examples of above alloys and compounds may comprise a material
having a chemical formula Ma.sub.sMb.sub.tLi.sub.u and a material
having a chemical formula Ma.sub.pMc.sub.qMd.sub.r. In these
chemical formulae, Ma is at least one selected from a group
consisting of metal element and semi-metal element capable of
forming an alloy together with lithium; Mb is at least one selected
from a group consisting of metal element and semi-metal element
other than lithium and Ma; Mc is at least one selected from the
non-metallic elements; Md is at least one selected from a group of
metal element and semi-metal element other than Ma; and s, t, u, p,
q and r meets: s>0, t.gtoreq.0, u.gtoreq.0, p>0, q>0 and
r.gtoreq.0.
[0054] Further, an inorganic compound not comprising lithium such
as MnO.sub.2, V.sub.2O.sub.5, V.sub.6O.sub.13, NiS, and MoS may be
used in the negative electrode.
[0055] The above lithium-ion battery further comprises an
electrolyte which may be one or more selected from a group
consisting of a gel electrolyte, a solid electrolyte and an
electrolytic solution, and the electrolytic solution comprises a
lithium salt and a non-aqueous solvent.
[0056] The lithium salt comprises at least one selected from a
group of LiPF.sub.6, LiBF.sub.4, LiAsF.sub.6, LiClO.sub.4,
LiB(C.sub.6H.sub.5).sub.4, LiCH.sub.3SO.sub.3, LiCF.sub.3SO.sub.3,
LiN(SO.sub.2CF.sub.3).sub.2, LiC(SO.sub.2CF.sub.3).sub.3,
LiSiF.sub.6, LiBOB, and lithium difluoroborate. For example, the
lithium salt is LiPF.sub.6 because it may provide high ionic
conductivity and improved cycle characteristics.
[0057] The non-aqueous solvent may be a carbonate compound, a
carboxylate compound, an ether compound, other organic solvents, or
a combination thereof.
[0058] The carbonate compound may be a chain carbonate compound, a
cyclic carbonate compound, a fluorocarbonate compound, or a
combination thereof.
[0059] Examples of the chain carbonate compound are diethyl
carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate
(DPC), methylpropyl carbonate (MPC), ethylene propyl carbonate
(EPC), and methyl ethyl carbonate (MEC) and combinations
thereof.
[0060] Examples of the cyclic carbonate compound are ethylene
carbonate (EC), propylene carbonate (PC), butylene carbonate (BC),
vinyl ethylene carbonate (VEC), and combinations thereof.
[0061] Examples of the fluorocarbonate compound are fluoroethylene
carbonate (FEC), 1,2-difluoroethylene carbonate,
1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate,
1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene
carbonate, 1-fluoro-1-methylethylene carbonate,
1,2-difluoro-1-methylethylene carbonate,
1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene
carbonate, and combinations thereof.
[0062] Examples of the carboxylate compound are methyl acetate,
ethyl acetate, n-propyl acetate, t-butyl acetate, methyl
propionate, ethyl propionate, propyl propionate,
.gamma.-butyrolactone, azlactone, valerolactone, caprolactone,
methyl formate and combinations thereof.
[0063] Examples of the ether compounds are dibutyl ether,
tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane,
ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, and
combinations thereof.
[0064] Examples of other organic solvents are dimethyl sulfoxide,
1,2-dioxolane, sulfolane, methyl sulfolane,
1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide,
dimethylformamide, acetonitrile, trimethyl phosphate, triethyl
phosphate, trioctyl phosphate, phosphate, and combinations
thereof.
[0065] Examples of the separator are polyethylene, polypropylene,
polyethylene terephthalate, polyimide, aramid and combinations
thereof, wherein the polyethylene is selected from the group
consisting of high density polyethylene, low density polyethylene,
ultra high molecular weight polyethylene, and combinations thereof.
In particular, polyethylene and polypropylene, which have a good
effect on preventing short circuits, may improve the stability of
the battery by the shutdown effect.
[0066] The separator surface may further comprise a porous layer
arranged on the surface of the separator, the porous layer
comprising inorganic particles and a binder. The inorganic particle
is selected from a group consisting of alumina (Al.sub.2O.sub.3),
silica (SiO.sub.2), magnesia (MgO), titania (TiO.sub.2), hafnium
oxide (HfO.sub.2), tin oxide (SnO.sub.2), cerium oxide (CeO.sub.2),
nickel oxide (NiO), zinc oxide (ZnO), calcium oxide (CaO),
zirconium oxide (ZrO.sub.2), yttrium oxide (Y.sub.2O.sub.3),
silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium
hydroxide, calcium hydroxide, barium sulfate and combinations
thereof. The binder is selected from the group consisting of
polyvinylidene fluoride, a copolymer of vinylidene
fluoride-hexafluoropropylene, polyamide, polyacrylonitrile,
polyacrylate, polyacrylic acid, polyacrylate, sodium
carboxymethylcellu lose, polyvinylpyrrolidone, polyvinyl ether,
polymethylmethacrylate, polytetrafluoroethylene,
polyhexafluoropropylene and combinations thereof.
[0067] The porous layer on the surface of the separator may improve
the heat resistance, oxidation resistance and electrolyte wetting
property of the separator, and enhance the adhesion between the
separator and the electrode.
[0068] Although the above is exemplified by a lithium-ion battery,
those skilled in the art can understand that the positive active
material of the present application may be used for other suitable
electrochemical devices after reading the present application. Such
electrochemical devices comprise any devices that generate an
electrochemical reaction, and specific examples thereof comprise
all kinds of primary batteries, secondary batteries or capacitors.
In particular, the electrochemical device is a lithium secondary
battery comprising a lithium metal battery, a lithium-ion battery,
and a lithium polymer battery.
[0069] Hereinafter, a lithium-ion battery is taken as an example
and a preparation of the lithium-ion battery is described in
conjunction with specific examples. Those skilled in the art will
understand that the preparation method described in the present
application is merely an example, and any other suitable
preparation methods are within the scope the present
application.
[0070] Some specific examples and comparative examples are listed
below to better illustrate the application.
EXAMPLE 1
[0071] A solution containing a precipitating agent (sodium
carbonate), a solution of a Co salt (cobalt sulfate) and a solution
of a metal M salt (magnesium nitrate, aluminum nitrate) are
cocurrent flowed and added into a reactor for fully mixing to
obtain a precipitate by coprecipitation reaction; the precipitate
is filtered, dried, and calcined at 780 to 1200.degree. C. to form
a precursor; subsequently, the precursor and lithium carbonate are
mixed in a certain ratio, and calcined at 920 to 1200.degree. C.,
wherein the element M is Mg and Al with a content of 211 ppm for
each element M; then, a grinding process is performed to remove
particles having a particle diameter of more than 12 .mu.m to
obtain a first positive active material having a particle diameter
of 12 .mu.m or less.
[0072] A solution containing a precipitating agent (sodium
carbonate), a solution of a Co salt (cobalt sulfate) and a solution
of a metal N salt (aluminum nitrate) are cocurrent flowed and added
into a reactor for fully mixing to obtain a precipitate by
coprecipitation reaction; the precipitate is filtered, dried, and
calcined at 780 to 1200.degree. C. to form a precursor;
subsequently, the precursor and lithium carbonate are mixed in a
certain ratio, and calcined at 920 to 1200.degree. C., wherein the
element N is Al with a content of 231 ppm; then, a grinding process
is performed to remove particles having a particle diameter of less
than 10 .mu.m to obtain a second positive active material having a
particle diameter of 10 .mu.m or more.
[0073] The two positive active materials (the first positive active
material and the second positive active material) prepared by the
above method are uniformly mixed in a ratio of 3:7 to obtain a
desired positive active material.
[0074] The obtained above positive active material, a conductive
agent of acetylene black, and a binder of polyvinylidene fluoride
(PVDF) are sufficiently stirred and uniformly mixed in a
N-methylpyrrolidone solvent system at a mass ratio of 94:3:3, and
then coated on a positive electrode current collector of Al foil
for drying, pressing, and cutting to obtain a positive
electrode.
[0075] Using the copper foil as the negative electrode current
collector, a layer of graphite slurry is uniformly coated on the
surface of the copper foil, and the slurry is constituted by 97.7
wt % artificial graphite, 1.3 wt % sodium carboxymethyl cellulose
(CMC), and 1.0 wt % styrene butadiene rubber (SBR). Then drying was
performed at 85.degree. C., followed by pressing, cutting,
slitting, and drying under a vacuum condition of 85.degree. C. for
4 h to prepare a negative electrode.
[0076] In a dry argon environment, LiPF.sub.6 is dissolved, in a
manner of with a concentration of 1.2M, into a non-aqueous solvent
in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and
diethyl carbonate (DEC) are mixed in an amount of 30wt %, 40wt %,
or 30wt %, respectively, and then 1 wt % of vinylene carbonate and
5 wt % of fluoroethylene carbonate are added, to obtain an
electrolyte.
[0077] The positive electrode and the negative electrode are wound,
and the positive electrode and the negative electrode are separated
by a PE separator, to prepare a wound electrode assembly. After
sealing at top side, spraying, vacuum drying, injecting with the
electrolyte and standing at a high temperature for the electrode
assembly, a finished lithium-ion battery may be obtained by
chemical conversion and capacity.
[0078] The lithium-ion battery is discharged to 2.5-3.0V after
repeated cycles. Then the lithium-ion battery is disassembled to
take out the positive electrode. The positive electrode is immersed
in dimethyl carbonate for 2 h or rinsed with dimethyl carbonate,
then dried naturally in a dry room, and baked in a muffle furnace
at 600.degree. C. for 2 h. Next, the positive electrode is
pulverized and sieved with a 200-mesh sieve to obtain a sample of
the positive active material required for the test (the ICP, SEM,
and EDS mentioned below are all tested for the sample prepared by
the method).
[0079] The Dv10 obtained by the laser particle diameter tester
(Thermal ICP6300) is 5.70 .mu.m, the Dv50 is 17.60 .mu.m and the
Dv90 is 32.90 .mu.m. The value of (Dv90-Dv50)-(Dv50-Dv10)
calculated according to equation (3) is 3.4. The content of the
element Co and the total content of the element M in the first
particle and the content of the element Co and the total content of
the element N in the second particle are respectively detected by
ICP (Inductively Coupled Plasma Spectrometer). The value of
(a/b)/(c/d) calculated according to equation (1) is 0.8. If only
qualitative analysis is performed, an energy spectrometer (EDS,
Zeiss SIGMA.sub.+X-maxEDS) test may be used to initially determine
the content of element M in the first particle and the content of
the element N the second particle.
EXAMPLE 2
[0080] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 2 are Ti and Al, and the element N in the
second positive active material is Mg.
EXAMPLE 3
[0081] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 3 are Ti, Al and Mg, and the elements N in the
second positive active material are Mg and Al.
EXAMPLE 4
[0082] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 4 are Ti, Al, Mg and Mn, and the elements N in
the second positive active material are Mg and Al.
EXAMPLE 5
[0083] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 5 are Ni, Al, Mg, Mn and Zr, and the elements N
in the second positive active material are Mg, Al and Mn.
EXAMPLE 6
[0084] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 6 are Ti, Al, Mg, Mn and Ni, and the elements N
in the second positive active material are Mg and Ti.
EXAMPLE 7
[0085] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 7 are Ti, Al, Mg, Mn and Ni, and the elements N
in the second positive active material are Mg, Al and Mn.
EXAMPLE 8
[0086] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 8 are Ti, Al, Mg, Mn, Ni and Zr, and the
elements N in the second positive active material are Mg, Al, Mn
and Ni.
EXAMPLE 9
[0087] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 9 are Ti, Al, Mg, Mn, Ni, Zr and La, and the
elements N in the second positive active material are Mg, Al and
Mn.
EXAMPLE 10
[0088] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 10 are Ti, Al, Mg, Mn, Ni, Zr and La, and the
elements N in the second positive active material are Mg, Al, Ni
and Mn.
EXAMPLE 11
[0089] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 11 are Ti, Al, Mg, Mn, and Ni with a content
for each of them being 293 ppm, and a grinding process is performed
to remove particles having a particle diameter of more than 11
.mu.m to obtain a first positive active material having a particle
diameter of 11 .mu.m or less. The elements N in the second positive
active material are Mg, Al and Mn with a content for each of them
being 287 ppm, and a grinding process is performed to remove
particles having a particle diameter of less than 9.3 .mu.m to
obtain a second positive active material having a particle diameter
of 9.3 .mu.m or more.
[0090] The Dv10 obtained by the laser particle diameter tester is
5.20 .mu.m, the Dv50 is 15.30 .mu.m and the Dv90 is 28.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 3. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 1.2.
EXAMPLE 12
[0091] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 12 are Ti, Al, Mg, Mn, and Ni with a content
for each of them being 376 ppm, and a grinding process is performed
to remove particles having a particle diameter of more than 11
.mu.m to obtain a first positive active material having a particle
diameter of 11 .mu.m or less. The elements N in the second positive
active material are Mg, Al and Mn with a content for each of them
being 311 ppm, and a grinding process is performed to remove
particles having a particle diameter of less than 9.3 .mu.m to
obtain a second positive active material having a particle diameter
of 9.3 .mu.m or more.
[0092] The Dv10 obtained by the laser particle diameter tester is
5.20 .mu.m, the Dv50 is 15.30 .mu.m and the Dv90 is 28.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 3. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 3.7.
EXAMPLE 13
[0093] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 13 are Ti, Al, Mg, Mn, and Ni with a content
for each of them being 528 ppm, and a grinding process is performed
to remove particles having a particle diameter of more than 11
.mu.m to obtain a first positive active material having a particle
diameter of 11 .mu.m or less. The elements N in the second positive
active material are Mg, Al and Mn with a content for each of them
being 449 ppm, and a grinding process is performed to remove
particles having a particle diameter of less than 9.3 .mu.m to
obtain a second positive active material having a particle diameter
of 9.3 .mu.m or more.
[0094] The Dv10 obtained by the laser particle diameter tester is
5.20 .mu.m, the Dv50 is 15.30 .mu.m and the Dv90 is 28.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 3. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 6.9.
EXAMPLE 14
[0095] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 14 are Ti, Al, Mg, Mn, and Ni with a content
for each of them being 689 ppm, and a grinding process is performed
to remove particles having a particle diameter of more than 11
.mu.m to obtain a first positive active material having a particle
diameter of 11 .mu.m or less. The elements N in the second positive
active material are Mg, Al and Mn with a content for each of them
being 574 ppm, and a grinding process is performed to remove
particles having a particle diameter of less than 9.3 .mu.m to
obtain a second positive active material having a particle diameter
of 9.3 .mu.m or more.
[0096] The Dv10 obtained by the laser particle diameter tester is
5.20 .mu.m, the Dv50 is 15.30 .mu.m and the Dv90 is 28.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 3. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 9.5.
EXAMPLE 15
[0097] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 15 are Ti, Al, Mg, Mn, and Ni with a content
for each of them being 823 ppm, and a grinding process is performed
to remove particles having a particle diameter of more than 11
.mu.m to obtain a first positive active material having a particle
diameter of 11 .mu.m or less. The elements N in the second positive
active material are Mg, Al and Mn with a content for each of them
being 679 ppm, and a grinding process is performed to remove
particles having a particle diameter of less than 9.3 .mu.m to
obtain a second positive active material having a particle diameter
of 9.3 .mu.m or more.
[0098] The Dv10 obtained by the laser particle diameter tester is
5.20 .mu.m, the Dv50 is 15.30 .mu.m and the Dv90 is 28.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 3. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 16.9.
EXAMPLE 16
[0099] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Example 16 are Ti, Al, Mg, Mn, and Ni with a content
for each of them being 1321 ppm, and a grinding process is
performed to remove particles having a particle diameter of more
than 11 .mu.m to obtain a first positive active material having a
particle diameter of 11 .mu.m or less. The elements N in the second
positive active material are Mg, Al and Mn with a content for each
of them being 972 ppm, and a grinding process is performed to
remove particles having a particle diameter of less than 9.3 .mu.m
to obtain a second positive active material having a particle
diameter of 9.3 .mu.m or more.
[0100] The Dv10 obtained by the laser particle diameter tester is
5.20 .mu.m, the Dv50 is 15.30 .mu.m and the Dv90 is 28.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 3. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 23.6.
EXAMPLE 17
[0101] The method here is the same as the preparation method of
Example 1, except that the each content of elements M in the first
positive active material in Example 17 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 11 .mu.m to obtain a first positive active material
having a particle diameter of 11 .mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 9.3 .mu.m to obtain a second positive active
material having a particle diameter of 9.3 .mu.m or more.
[0102] The Dv10 obtained by the laser particle diameter tester is
2.50 .mu.m, the Dv50 is 14.70 .mu.m and the Dv90 is 28.50 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 1.6. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 2.6.
EXAMPLE 18
[0103] The method here is the same as the preparation method of
Example 2, except that the each content of elements M in the first
positive active material in Example 18 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 11 .mu.m to obtain a first positive active material
having a particle diameter of 11 .mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 7 .mu.m to obtain a second positive active
material having a particle diameter of 7 .mu.m or more.
[0104] The Dv10 obtained by the laser particle diameter tester is
1.90 .mu.m, the Dv50 is 11.50 .mu.m and the Dv90 is 23.50 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 2.4. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 2.6.
EXAMPLE 19
[0105] The method here is the same as the preparation method of
Example 3, except that The each content of elements M in the first
positive active material in Example 19 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 13 .mu.m to obtain a first positive active material
having a particle diameter of 13 .mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 11 .mu.m to obtain a second positive active
material having a particle diameter of 11 .mu.m or more.
[0106] The Dv10 obtained by the laser particle diameter tester is
2.70 .mu.m, the Dv50 is 17.20 .mu.m and the Dv90 is 26.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is -5.3. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 2.6.
EXAMPLE 20
[0107] The method here is the same as the preparation method of
Example 4, except that The each content of elements M in the first
positive active material in Example 20 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 11 .mu.m to obtain a first positive active material
having a particle diameter of 11 .mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 9.3 .mu.m to obtain a second positive active
material having a particle diameter of 9.3 .mu.m or more.
[0108] The Dv10 obtained by the laser particle diameter tester is
2.5 .mu.m, the Dv50 is 14.70 .mu.m and the Dv90 is 28.50 .mu.m. The
value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to equation
(3) is 1.6. The content of the element Co and the total content of
the element M in the first particle and the content of the element
Co and the total content of the element N in the second particle
are respectively detected by ICP (Inductively Coupled Plasma
Spectrometer). The value of (a/b)/(c/d) calculated according to
equation (1) is 2.6.
EXAMPLE 21
[0109] The method here is the same as the preparation method of
Example 5, except that The each content of elements M in the first
positive active material in Example 21 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 13 .mu.m to obtain a first positive active material
having a particle diameter of 13 .mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 11 .mu.m to obtain a second positive active
material having a particle diameter of 11 .mu.m or more.
[0110] The Dv10 obtained by the laser particle diameter tester is
3.70 .mu.m, the Dv50 is 17.20 .mu.m and the Dv90 is 32.0 .mu.m. The
value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to equation
(3) is 1.3. The content of the element Co and the total content of
the element M in the first particle and the content of the element
Co and the total content of the element N in the second particle
are respectively detected by ICP (Inductively Coupled Plasma
Spectrometer). The value of (a/b)/(c/d) calculated according to
equation (1) is 2.6.
EXAMPLE 22
[0111] The method here is the same as the preparation method of
Example 6, except that The each content of elements M in the first
positive active material in Example 22 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 15 .mu.m to obtain a first positive active material
having a particle diameter of 15 .mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 12 .mu.m to obtain a second positive active
material having a particle diameter of 12 .mu.m or more.
[0112] The Dv10 obtained by the laser particle diameter tester is
4.10 .mu.m, the Dv50 is 18.50 .mu.m and the Dv90 is 32.90 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 0. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 2.6.
EXAMPLE 23
[0113] The method here is the same as the preparation method of
Example 7, except that The each content of elements M in the first
positive active material in Example 23 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 6 .mu.m to obtain a first positive active material
having a particle diameter of 6 .mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 5 .mu.m to obtain a second positive active
material having a particle diameter of 5 .mu.m or more.
[0114] The Dv10 obtained by the laser particle diameter tester is
1.50 .mu.m, the Dv50 is 9.70 .mu.m and the Dv90 is 20.20 .mu.m. The
value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to equation
(3) is 2.3. The content of the element Co and the total content of
the element M in the first particle and the content of the element
Co and the total content of the element N in the second particle
are respectively detected by ICP (Inductively Coupled Plasma
Spectrometer). The value of (a/b)/(c/d) calculated according to
equation (1) is 2.6.
EXAMPLE 24
[0115] The method here is the same as the preparation method of
Example 8, except that The each content of elements M in the first
positive active material in Example 24 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 13 .mu.m to obtain a first positive active material
having a particle diameter of 13 .mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 11 .mu.m to obtain a second positive active
material having a particle diameter of 11 .mu.m or more.
[0116] The Dv10 obtained by the laser particle diameter tester is
3.20 .mu.m, the Dv50 is 17 .mu.m and the Dv90 is 33.30 .mu.m. The
value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to equation
(3) is 2.5. The content of the element Co and the total content of
the element M in the first particle and the content of the element
Co and the total content of the element N in the second particle
are respectively detected by ICP (Inductively Coupled Plasma
Spectrometer). The value of (a/b)/(c/d) calculated according to
equation (1) is 2.6.
EXAMPLE 25
[0117] The method here is the same as the preparation method of
Example 9, except that The each content of elements M in the first
positive active material in Example 25 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 11 .mu.m to obtain a first positive active material
having a particle diameter of 11.mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 9.3 .mu.m to obtain a second positive active
material having a particle diameter of 9.3 .mu.m or more.
[0118] The Dv10 obtained by the laser particle diameter tester is
2.50 .mu.m, the Dv50 is 14.70 .mu.m and the Dv90 is 28.50 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 1.6. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 2.6.
EXAMPLE 26
[0119] The method here is the same as the preparation method of
Example 10, except that The each content of elements M in the first
positive active material in Example 26 is 303 ppm, and a grinding
process is performed to remove particles having a particle diameter
of more than 11 .mu.m to obtain a first positive active material
having a particle diameter of 11 .mu.m or less. The each content of
elements N in the second positive active material is 292 ppm, and a
grinding process is performed to remove particles having a particle
diameter of less than 9.3 .mu.m to obtain a second positive active
material having a particle diameter of 9.3 .mu.m or more.
[0120] The Dv10 obtained by the laser particle diameter tester is
2.50 .mu.m, the Dv50 is 14.70 .mu.m and the Dv90 is 28.50 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 1.6. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 2.6.
COMPARATIVE EXAMPLE 1
[0121] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Comparative Example 1 are Mg, Al and Mn, and a grinding
process is performed to remove particles having a particle diameter
of more than 15 .mu.m to obtain a first positive active material
having a particle diameter of 15 .mu.m or less. The elements N in
the second positive active material are Mg, Al, Mn and Ni, and a
grinding process is performed to remove particles having a particle
diameter of less than 11 .mu.m to obtain a first positive active
material having a particle diameter of 11 .mu.m or more.
[0122] The Dv10 obtained by the laser particle diameter tester is
5.70 .mu.m, the Dv50 is 17.60 .mu.m and the Dv90 is 32.90 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 3.4. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 0.8.
COMPARATIVE EXAMPLE 2
[0123] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Comparative Example 2 are Mg, Al and Mn, and a grinding
process is performed to remove particles having a particle diameter
of more than 11 .mu.m to obtain a first positive active material
having a particle diameter of 11 .mu.m or less. The elements N in
the second positive active material are Mg, Al, Mn and Ni, and a
grinding process is performed to remove particles having a particle
diameter of less than 10 .mu.m to obtain a first positive active
material having a particle diameter of 10 .mu.m or more.
[0124] The Dv10 obtained by the laser particle diameter tester is
4.30 .mu.m, the Dv50 is 15.70 .mu.m and the Dv90 is 29.70 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 2.6. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 0.8.
COMPARATIVE EXAMPLE 3
[0125] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Comparative Example 3 are Mg, Al and Mn, and a grinding
process is performed to remove particles having a particle diameter
of more than 12 .mu.m to obtain a first positive active material
having a particle diameter of 12 .mu.m or less. The elements N in
the second positive active material are Mg, Al, Mn and Ni, and a
grinding process is performed to remove particles having a particle
diameter of less than 11 .mu.m to obtain a first positive active
material having a particle diameter of 11 .mu.m or more.
[0126] The Dv10 obtained by the laser particle diameter tester is
7.10 .mu.m, the Dv50 is 16.60 .mu.m and the Dv90 is 30.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 4.3. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 0.8.
COMPARATIVE EXAMPLE 4
[0127] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Comparative Example 4 are Mg, Al and Mn, and a grinding
process is performed to remove particles having a particle diameter
of more than 14 .mu.m to obtain a first positive active material
having a particle diameter of 14 .mu.m or less. The elements N in
the second positive active material are Mg, Al, Mn and Ni, and a
grinding process is performed to remove particles having a particle
diameter of less than 12 .mu.m to obtain a first positive active
material having a particle diameter of 12 .mu.m or more.
[0128] The Dv10 obtained by the laser particle diameter tester is
6.60 .mu.m, the Dv50 is 18.00 .mu.m and the Dv90 is 33.20 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 3.8. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 0.8.
COMPARATIVE EXAMPLE 5
[0129] The method here is the same as the preparation method of
Example 1, except that the elements M in the first positive active
material in Comparative Example 5 are Mg, Al and Mn, and a grinding
process is performed to remove particles having a particle diameter
of more than 18 .mu.m to obtain a first positive active material
having a particle diameter of 18 .mu.m or less. The elements N in
the second positive active material are Mg, Al, Mn and Ni, and a
grinding process is performed to remove particles having a particle
diameter of less than 16 .mu.m to obtain a first positive active
material having a particle diameter of 16 .mu.m or more.
[0130] The Dv10 obtained by the laser particle diameter tester is
4.60 .mu.m, the Dv50 is 18.20 .mu.m and the Dv90 is 34.50 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 2.7. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 0.8.
COMPARATIVE EXAMPLE 6
[0131] A solution containing a precipitating agent (sodium
carbonate), a solution of a Co salt (cobalt sulfate) and a solution
of a metal M salt (magnesium nitrate, aluminum nitrate, manganese
nitrate, nickel nitrate) are cocurrent flowed and added into a
reactor for fully mixing to obtain a precipitate by coprecipitation
reaction; the precipitate is filtered, dried, and calcined at 780
to 1200.degree. C. to form a precursor; subsequently, the precursor
and lithium carbonate are mixed in a certain ratio, and calcined at
920 to 1200.degree. C., wherein the element M is Mg, Al, Mn and Ni
with a content of 209 ppm for each element M; a grinding process is
performed to remove particles having a particle diameter of more
than 9.5 .mu.m to obtain a first positive active material having a
particle diameter of 9.5 .mu.m or less.
[0132] A solution containing a precipitating agent (sodium
carbonate), a solution of a Co salt (cobalt sulfate) and a solution
of a metal N salt (magnesium nitrate, aluminum nitrate, manganese
nitrate, nickel nitrate) are cocurrent flowed and added into a
reactor for fully mixing to obtain a precipitate by coprecipitation
reaction; the precipitate is filtered, dried, and calcined at 780
to 1200.degree. C. to form a precursor; subsequently, the precursor
and lithium carbonate are mixed in a certain ratio, and calcined at
920 to 1200.degree. C., wherein the element N is Mg, Al, Mn and Ni
with a content of 263 ppm for each element N; then, a grinding
process is performed to remove particles having a particle diameter
of less than 8.6 .mu.m to obtain a second positive active material
having a particle diameter of 8.6 .mu.m or more.
[0133] The first positive active material and the second positive
active material described above are prepared into a lithium-ion
battery according to the method in Example 1, and then the
lithium-ion battery is disassembled to obtain a positive active
material sample for testing.
[0134] The Dv10 obtained by the laser particle diameter tester is
5.20 .mu.m, the Dv50 is 15.30 .mu.m and the Dv90 is 28.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 3. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 0.8.
COMPARATIVE EXAMPLE 7
[0135] A solution containing a precipitating agent (sodium
carbonate), a solution of a Co salt (cobalt sulfate) and a solution
of a metal M salt (magnesium nitrate, aluminum nitrate, manganese
nitrate, nickel nitrate) are cocurrent flowed and added into a
reactor for fully mixing to obtain a precipitate by coprecipitation
reaction; the precipitate is filtered, dried, and calcined at 780
to 1200.degree. C. to form a precursor; subsequently, the precursor
and lithium carbonate are mixed in a certain ratio, and calcined at
920 to 1200.degree. C., wherein the element M is Mg, Al, Mn and Ni
with a contents of 223 ppm for each element M; a grinding process
is performed to remove particles having a particle diameter of more
than 12.3 .mu.m to obtain a first positive active material having a
particle diameter of 12.3 .mu.m or less.
[0136] A solution containing a precipitating agent (sodium
carbonate), a solution of a Co salt (cobalt sulfate) and a solution
of a metal N salt (magnesium nitrate, aluminum nitrate, manganese
nitrate, nickel nitrate) are cocurrent flowed and added into a
reactor for fully mixing to obtain a precipitate by coprecipitation
reaction; the precipitate is filtered, dried, and calcined at 780
to 1200.degree. C. to form a precursor; subsequently, the precursor
and lithium carbonate are mixed in a certain ratio, and calcined at
920 to 1200.degree. C., wherein the element N is Mg, Al, Mn and Ni
with a content of 249 ppm for each element N; then, a grinding
process is performed to remove particles having a particle diameter
of less than 10.3 .mu.m to obtain a second positive active material
having a particle diameter of 10.3 .mu.m or more.
[0137] The first positive active material and the second positive
active material described above are prepared into a lithium-ion
battery according to the method in Example 1, and then the
lithium-ion battery is disassembled to obtain a positive active
material sample for testing.
[0138] The Dv10 obtained by the laser particle diameter tester is
8.37 .mu.m, the Dv50 is 17.98 .mu.m and the Dv90 is 32.40 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 4.81. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 0.8.
COMPARATIVE EXAMPLE 8
[0139] A solution containing a precipitating agent (sodium
carbonate), a solution of a Co salt (cobalt sulfate) and a solution
of a metal M salt (magnesium nitrate, aluminum nitrate, manganese
nitrate, nickel nitrate) are combined and added into a reactor for
fully mixing to obtain a precipitate by coprecipitation reaction;
the precipitate is filtered, dried, and calcined at 780 to
1200.degree. C. to form a precursor; subsequently, the precursor
and lithium carbonate are mixed in a certain ratio, and calcined at
920 to 1200.degree. C., wherein the element M is Mg, Al, Mn and Ni
with a content of 221 ppm for each element M; a grinding process is
performed to remove particles having a particle diameter of more
than 11.8 .mu.m to obtain a first positive active material having a
particle diameter of 11.8 .mu.m or less.
[0140] A solution containing a precipitating agent (sodium
carbonate), a solution of a Co salt (cobalt sulfate) and a solution
of a metal N salt (magnesium nitrate, aluminum nitrate, manganese
nitrate, nickel nitrate) are cocurrent flowed and added into a
reactor for fully mixing to obtain a precipitate by coprecipitation
reaction; the precipitate is filtered, dried, and calcined at 780
to 1200.degree. C. to form a precursor; subsequently, the precursor
and lithium carbonate are mixed in a certain ratio, and calcined at
920 to 1200.degree. C., wherein the element N is Mg, Al, Mn and Ni
with a content of 239 ppm for each element N; then, a grinding
process is performed to remove particles having a particle diameter
of less than 9.7 .mu.m to obtain a second positive active material
having a particle diameter of 9.7 .mu.m or more.
[0141] The first positive active material and the second positive
active material described above are prepared into a lithium-ion
battery according to the method in Example 1, and then the
lithium-ion battery is disassembled to obtain a positive active
material sample for testing.
[0142] The Dv10 obtained by the laser particle diameter tester is
6.40 .mu.m, the Dv50 is 16.50 .mu.m and the Dv90 is 30.60 .mu.m.
The value of (Dv90-Dv50)-(Dv50-Dv10) calculated according to
equation (3) is 4. The content of the element Co and the total
content of the element M in the first particle and the content of
the element Co and the total content of the element N in the second
particle are respectively detected by ICP (Inductively Coupled
Plasma Spectrometer). The value of (a/b)/(c/d) calculated according
to equation (1) is 0.8.
[0143] The following are the test methods for related
parameters:
[0144] 1. Compact Density of Positive Electrode
[0145] The formed lithium-ion battery is discharged to 2.5 to 3.0V,
then the lithium-ion battery is disassembled to take out the
positive electrode; the positive electrode is placed in DMC and
soaked for 2 hours, and dried naturally in the drying room; 6
pieces of the positive electrode and the positive electrode current
collector are punched out with a mold of 154.025 mm.sup.2; the
analytical balance (Shanghai Jingke Tianmei Electronic Balance,
FA2004B) is used to weigh the total weight of 6 pieces of positive
electrodes as Mc g and the total weight of the 6 pieces of positive
electrode current collectors as Ma g; a micrometer (Japan Mitutoyo
micrometer, 293-230) is used to measure the average thickness of
the 6 pieces of positive electrodes as T1 mm and the average
thickness of the 6 pieces of positive electrode current collectors
as T2 mm, so PD=[(Mc-Ma)/6]/(T1-T2)/154.025*1000, g/cm.sup.3,
wherein PD indicates the compact density of the positive electrode.
The compact density of the positive electrode measured by the
testing method is the compact density after pressing.
[0146] 2. Initial Discharge Capacity of Lithium-Ion Battery
[0147] After the lithium-ion battery is formed, it is charged with
a constant current of 0.5 C to a voltage of 4.4 V at a room
temperature, and then charged with a constant voltage of 4.4 V
until the current is 0.05 C. The discharge capacity at a discharge
of 0.2 C is measured, and the standard capacity is 2990 mAh.
[0148] 3. Discharge Capacity at 500 Cycles
[0149] After the lithium-ion battery is formed, it is charged with
a constant current of 0.5 C to a voltage of 4.4 V at a room
temperature, and discharged with a constant voltage of 4.4 V until
the current is 0.05 C, and discharged with 0.2 C. After 500 cycles,
the ratio of the amount of electricity discharged at the 500th
cycle to the initial discharge capacity is calculated, 10=2990
mAh.
[0150] 4. DSC (Differential Scanning Calorimetry) Initial Peak of
Initial Peak of Heat Loss
[0151] After the lithium-ion battery is formed, it is charged with
a constant current of 0.5 C to a voltage of 4.4 V at a room
temperature, and then charged with a constant voltage of 4.4 V
until the current is 0.05 C. Then, the lithium-ion battery is
disassembled in a dry room, and the fully charged positive
electrode is taken as a test sample. The sample is subjected to DSC
testing using a Netzsch STA449 DSC/TGA (Germany STA449F3) with a
test temperature of 50-450.degree. C.
[0152] The compact density, the initial discharge capacity, the
discharge capacity at 500 cycles, and initial peak of initial peak
of heat loss for the DSC test are tested for each of the samples of
Examples 1-26 and Comparative Examples 1-8, and the testing methods
are respectively determined according to the above-described
measurement methods for compact density, test method of initial
discharge capacity, the discharge capacity at 500 cycles, and
initial peak of initial peak of heat loss for the DSC test.
[0153] The measurement results of the Examples 1-26 and Comparative
Examples 1-8 are shown in Table 1 below.
TABLE-US-00001 TABLE 1 thermal Parameters of examples and
comparative examples performance of stability of parameters of the
present application lithium-ion battery material particle size
compact discharge DSC test doping doping distribution density of
initial capacity at main peak element in element in (a/b)/ (D90 -
positive discharge the 500th of initial first second (c/d) =
particle size (.mu.m) D50) - electrode capacity cycles heat loss
particle particle ad/bc DV10 DV50 DV90 (D50 - D10) (g/cm.sup.3)
(mAh) (%) peak .degree. C. Examples 1 Mg, Al Al 0.8 5.70 17.60
32.90 3.4 4.13 3104 83.7 237.9 2 Al, Ti Mg 0.8 5.70 17.60 32.90 3.4
4.09 3125 82.5 236.4 3 Mg, Al, Ti Mg, Al 0.8 5.70 17.60 32.90 3.4
4.02 3136 82.8 234.2 4 Mg, Al, Ti, Mg, Al 0.8 5.70 17.60 32.90 3.4
4.05 3117 82.9 237.5 Mn 5 Mg, Al, Ni, Mg, Al, Mn 0.8 5.70 17.60
32.90 3.4 3.92 3152 82.5 235.7 Mn, Zr 6 Mg, Al, Ti, Mg, Ti 0.8 5.70
17.60 32.90 3.4 3.96 3144 82.9 234.4 Ni, Mn 7 Mg, Al, Ti, Mg, Al,
Mn 0.8 5.70 17.60 32.90 3.4 3.98 3131 82.3 235.8 Ni, Mn 8 Mg, Al,
Ni, Mg, Al, Ni, 0.8 5.70 17.60 32.90 3.4 4.04 3108 82.5 236.7 Mn,
Ti, Zr Mn 9 Mg, Al, Ni, Mg, Al, Mn 0.8 5.70 17.60 32.90 3.4 4.1
3119 82.9 235.2 Mn, Ti, Zr, La 10 Mg, Al, Ni, Mg, Al, Ni, 0.8 5.70
17.60 32.90 3.4 3.92 3122 83.6 237.9 Mn, Ti, Zr, Mn La 11 Mg, Al,
Ti, Mg, Al, Mn 1.2 5.20 15.30 28.40 3 3.98 3134 85.4 256.7 Ni, Mn
12 Mg, Al, Ti, Mg, Al, Mn 3.7 5.20 15.30 28.40 3 3.95 3107 84.5
256.3 Ni, Mn 13 Mg, Al, Ti, Mg, Al, Mn 6.9 5.20 15.30 28.40 3 3.93
3125 86.8 253.6 Ni, Mn 14 Mg, Al, Ti, Mg, Al, Mn 9.5 5.20 15.30
28.40 3 4 3010 89.6 257.5 Ni, Mn 15 Mg, Al, Ti, Mg, Al, Mn 16.9
5.20 15.30 28.40 3 4.01 3018 89.5 259.3 Ni, Mn 16 Mg, Al, Ti, Mg,
Al, Mn 23.6 5.20 15.30 28.40 3 4.02 3011 85.7 259.7 Ni, Mn 17 Mg,
Al Al 2.6 2.5 14.7 28.5 1.6 4.13 3152 86.7 253.8 18 Al, Ti Mg 2.6
1.9 11.5 23.5 2.4 4.1 3144 87.3 255.2 19 Mg, Al, Ti Mg, Al 2.6 2.7
17.2 26.4 -5.3 4.03 3131 87.4 259.6 20 Mg, Al, Ti, Mg, Al 2.6 2.5
14.7 28.5 1.6 4.06 3108 85.1 253.5 Mn 21 Mg, Al, Ni, Mg, Al, Mn 2.6
3.7 17.2 32.0 1.3 4.03 3119 85.6 260.1 Mn, Zr 22 Mg, Al, Ti, Mg, Ti
2.6 4.1 18.5 32.9 0.0 4.07 3122 86.5 257.2 Ni, Mn 23 Mg, Al, Ti,
Mg, Al, Mn 2.6 1.5 9.7 20.2 2.3 4.11 3134 87.3 256.2 Ni, Mn 24 Mg,
Al, Ni, Mg, Al, Ni, 2.6 3.2 17.0 33.3 2.5 4.1 3107 88.4 261 Mn, Ti,
Zr Mn 25 Mg, Al, Ni, Mg, Al, Mn 2.6 2.5 14.7 28.5 1.6 4.11 3125
89.7 259.3 Mn, Ti, Zr, La 26 Mg, Al, Ni, Mg, Al, Ni, 2.6 2.5 14.7
28.5 1.6 4.08 3010 87.3 254.2 Mn, Ti, Zr, Mn La Comparative
Examples 1 Mg, Al, Mn Mg, Al, Mn, 0.8 5.70 17.60 32.90 3.4 3.89
2990 80.1 222.7 Ni 2 Mg, Al, Mn Mg, Al, Mn, 0.8 4.30 15.70 29.70
2.6 3.81 2998 81.1 221.3 Ni 3 Mg, Al, Mn Mg, Al, Mn, 0.8 7.10 16.60
30.40 4.3 3.89 2977 80.7 220.1 Ni 4 Mg, Al, Mn Mg, Al, Mn, 0.8 6.60
18.00 33.20 3.8 3.83 3006 80.8 223.1 Ni 5 Mg, Al, Mn Mg, Al, Mn,
0.8 4.60 18.20 34.50 2.7 3.82 3001 81.8 227.2 Ni 6 Mg, Al, Mn, Mg,
Al, Mn, 0.8 5.20 15.30 28.40 3 3.8 2995 81.4 212 Ni Ni 7 Mg, Al,
Mn, Mg, Al, Mn, 0.8 8.37 17.98 32.40 4.81 3.83 2998 81.1 219.4 Ni
Ni 8 Mg, Al, Mn, Mg, Al, Mn, 0.8 6.40 16.50 30.60 4 3.85 3004 81.7
227.7 Ni Ni
[0154] From the experimental data in Table 1, by comparing the
results of Examples 1-26 and Comparative Examples 1-8, it shows
that: when the number of the type of the element M in the first
particle of the positive active material is larger than that of the
element N in the second particle, the initial discharge capacity of
the lithium-ion battery is high, the discharge capacity at the
500th cycles is increased, and the thermal stability of the
positive electrode is improved.
[0155] By comparing the results of Examples 1-10 and 11-16, it may
be known that: when the number of the type of the element M in the
first particle of the positive active material is larger than that
of the element N in the second particle, the discharge capacity at
the 500th cycles of the lithium-ion battery is effectively improved
and the thermal stability of the positive electrode is higher when
the total content of the element M and the content of the element
Co in the first particle and the total content of the element N and
the content of the element Co in the second particle meet the
equation (2) or (3) in the case where
(Dv90-Dv50)-(Dv50-Dv10).ltoreq.2.5 is not met.
[0156] By comparing the results of Examples 11-16 and 17-26, it may
be known that: when the number of the type of the element M in the
first particle of the positive active material is larger than that
of the element N in the second particle while meeting
(Dv90-Dv50)-(Dv50-Dv10).ltoreq.2.5, the compact density of the
lithium-ion battery is improved and the energy density of the
positive electrode is higher when the total content of the element
M and the content of the element Co in the first particle and the
total content of the element N and the content of the element Co in
the second particle meet the equation (2) or (3).
[0157] Furthermore, FIG. 1A and FIG. 1B show a scanning electron
microscope (SEM) view of the positive active material according to
Example 1 of the present application and Comparative Example 6
respectively. As can be seen from FIG. 1A and FIG. 1B, comparing
with the positive active material of Comparative Example 6, the
positive active material of Example 1 was mixed with a smaller
first particle and a larger second particle, which is a stacking of
the smaller particle and the larger particle, thus the compact
density of the positive electrode can be improved.
[0158] FIG. 2 shows a particle size distribution curve of the
positive active material according to Example 1 of the present
application and Comparative Example 6. As can be seen from FIG. 2,
the positive active material of Example 1 has a distinct double
peak compared to the single peak of Comparative Example 6, and the
peak height of the second peak is greater than the peak height of
the first peak.
[0159] FIG. 3 shows the results of testing thermal stability of
electrode for the positive active material according to Example 1
of the present application and Comparative Example 6. As can be
seen from FIG. 3, the temperature (254.5.degree. C.) of main peak
of initial heat loss peak of the sample in Example 1 is
significantly higher than that (223.1.degree. C)of the sample in
Comparative Example 6, indicating that the thermal stability of the
sample in Example 1 is higher than that in Comparative Example
6.
[0160] Those skilled in the art will appreciate that the
above-described examples are merely exemplary examples, and various
changes, substitutions and changes may be made without departing
from the spirit and scope of the present application.
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