U.S. patent application number 16/546323 was filed with the patent office on 2019-12-12 for oligomer-polymer and lithium battery.
This patent application is currently assigned to National Taiwan University of Science and Technology. The applicant listed for this patent is Industrial Technology Research Institute, National Taiwan University of Science and Technology. Invention is credited to Chorng-Shyan Chern, Jung-Mu Hsu, Bing-Joe Hwang, Jing-Pin Pan, Quoc Thai Pham, Fu-Ming Wang, Chang-Rung Yang.
Application Number | 20190379046 16/546323 |
Document ID | / |
Family ID | 61728616 |
Filed Date | 2019-12-12 |
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United States Patent
Application |
20190379046 |
Kind Code |
A1 |
Wang; Fu-Ming ; et
al. |
December 12, 2019 |
OLIGOMER-POLYMER AND LITHIUM BATTERY
Abstract
An oligomer-polymer is provided. The oligomer-polymer is
obtained by the polymerization reaction of a compound containing an
ethylenically unsaturated group and a nucleophile compound, wherein
the nucleophile compound includes the compound shown in formula 1:
##STR00001## A lithium battery including an anode, a cathode, an
isolation film, an electrolyte solution, and a package structure is
also provided, wherein the cathode includes the
oligomer-polymer.
Inventors: |
Wang; Fu-Ming; (Taipei,
TW) ; Hwang; Bing-Joe; (Taipei, TW) ; Chern;
Chorng-Shyan; (Taipei, TW) ; Hsu; Jung-Mu;
(Penghu County, TW) ; Pan; Jing-Pin; (Hsinchu
County, TW) ; Yang; Chang-Rung; (Hsinchu City,
TW) ; Pham; Quoc Thai; (Taipei, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
National Taiwan University of Science and Technology
Industrial Technology Research Institute |
Taipei
Hsinchu |
|
TW
TW |
|
|
Assignee: |
National Taiwan University of
Science and Technology
Taipei
TW
Industrial Technology Research Institute
Hsinchu
TW
|
Family ID: |
61728616 |
Appl. No.: |
16/546323 |
Filed: |
August 21, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15619061 |
Jun 9, 2017 |
|
|
|
16546323 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01M 10/0525 20130101;
H01M 2004/028 20130101; H01M 4/608 20130101; H01M 2300/0025
20130101; C08G 83/005 20130101; H01M 10/0567 20130101 |
International
Class: |
H01M 4/60 20060101
H01M004/60; C08G 83/00 20060101 C08G083/00; H01M 10/0525 20060101
H01M010/0525; H01M 10/0567 20060101 H01M010/0567 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 7, 2016 |
TW |
105136149 |
Claims
1. An oligomer-polymer obtained by a polymerization reaction of a
compound containing an ethylenically unsaturated group and a
nucleophile compound, wherein the nucleophile compound comprises a
compound shown in formula 1: ##STR00013##
2. The oligomer-polymer of claim 1, wherein a mole ratio of the
compound containing an ethylenically unsaturated group and the
nucleophile compound is between 2:1 and 1:1.
3. The oligomer-polymer of claim 1, wherein the compound containing
an ethylenically unsaturated group comprises a maleimide-based
compound.
4. The oligomer-polymer of claim 3, wherein the maleimide-based
compound comprises monomaleimide or bismaleimide.
5. The oligomer-polymer of claim 1, wherein the nucleophile
compound further comprises a compound shown in formula 2 below:
##STR00014##
6. The oligomer-polymer of claim 5, wherein in the nucleophile
compound, a mole ratio of the compound shown in formula 1 and the
compound shown in formula 2 is between 2:1 and 1:1.
7. The oligomer-polymer of claim 1, wherein a reaction temperature
of the polymerization reaction is between 25.degree. C. and
200.degree. C.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a divisional application of U.S. patent
application Ser. No. 15/619,061, filed on Jun. 9, 2017, now
pending, which claims the priority benefit of Taiwan application
serial no. 105136149, filed on Nov. 7, 2016. The entirety of each
of the above-mentioned patent applications is hereby incorporated
by reference herein and made a part of this specification.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The invention relates to an oligomer-polymer, and more
particularly, to an oligomer-polymer for a lithium battery.
Description of Related Art
[0003] Since primary batteries are not environment-friendly, the
market demand for secondary lithium batteries with characteristics
such as rechargeability, light weight, high voltage value, and high
energy density has been growing in recent years. As a result, the
current performance requirements for secondary lithium batteries
such as light weight, durability, high voltage, high energy
density, and high safety have become higher. In particular,
secondary lithium batteries have very high potential in the
application and expandability in light electric vehicles, electric
vehicles, and the large power storage industry.
[0004] However, among the commercialized secondary lithium
batteries in the general market, since lithium transition metal
oxide is used as the cathode, the cathode readily reacts with the
electrolyte solution in high temperature applications and becomes
damaged. As a result, oxygen in the lithium metal oxide is released
and becomes part of a combustion reaction. This is one of the main
causes for the explosion, swelling, and performance degradation of
the secondary lithium battery. Therefore, continuously maintaining
good structural stability of the cathode material in high
temperature applications is one of the desired goals of those
skilled in the art.
SUMMARY OF THE INVENTION
[0005] The invention provides an oligomer-polymer that can be
applied in the cathode material of a lithium battery such that the
lithium battery still has good performance in a high-temperature
environment.
[0006] The oligomer-polymer of the invention is obtained by the
polymerization reaction of a compound containing an ethylenically
unsaturated group and a nucleophile compound, wherein the
nucleophile compound includes a compound shown in formula 1
below:
##STR00002##
[0007] In an embodiment of the invention, the mole ratio of the
compound containing an ethylenically unsaturated group and the
nucleophile compound is between 2:1 and 1:1.
[0008] In an embodiment of the invention, the compound containing
an ethylenically unsaturated group includes a maleimide-based
compound.
[0009] In an embodiment of the invention, the maleimide-based
compound includes, for instance, monomaleimide or bismaleimide.
[0010] In an embodiment of the invention, the nucleophile compound
further includes the compound shown in formula 2 below:
##STR00003##
[0011] In an embodiment of the invention, in the nucleophile
compound, the mole ratio of the compound shown in formula 1 and the
compound shown in formula 2 is between 2:1 and 1:1.
[0012] In an embodiment of the invention, the reaction temperature
of the polymerization reaction is between 25.degree. C. and
200.degree. C.
[0013] A lithium battery of the invention includes an anode, a
cathode, an isolation film, an electrolyte solution, and a package
structure. The cathode and the anode are separately disposed, and
the cathode includes any of the above oligomer-polymers. The
isolation film is disposed between the anode and the cathode, and
the isolation film, the anode, and the cathode define a housing
region. The electrolyte solution is disposed in the housing region.
The package structure packages the anode, the cathode, and the
electrolyte solution.
[0014] In an embodiment of the invention, the electrolyte solution
includes an organic solvent, a lithium salt, and an additive.
[0015] In an embodiment of the invention, the additive includes
monomaleimide, polymaleimide, bismaleimide, polybismaleimide, a
copolymer of bismaleimide and monomaleimide, vinylene carbonate, or
a mixture thereof.
[0016] Based on the above, by using the compound containing an
ethylenically unsaturated group and the nucleophile compound
including the compound shown in formula 1 to prepare the
oligomer-polymer of the invention, the oligomer-polymer of the
invention can be applied in the cathode material of a lithium
battery, such that the lithium battery still has good capacitance,
battery efficiency, and charge and discharge cycle life even in
high-temperature operation.
[0017] In order to make the aforementioned features and advantages
of the disclosure more comprehensible, embodiments accompanied with
figures are described in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention.
[0019] FIG. 1 is a cross-sectional schematic of a lithium battery
according to an embodiment of the invention.
[0020] FIG. 2 shows a curve diagram illustrating the relationship
between capacitance and voltage of the lithium battery of each of
Example 1 and Comparative Examples 1 and 2 of the invention at room
temperature.
[0021] FIG. 3 shows a diagram illustrating the relationship between
the number of charge and discharge cycles and discharge capacity of
the lithium battery of each of Example 1 and Comparative Example 2
of the invention at room temperature.
[0022] FIG. 4 shows a diagram illustrating the relationship between
the number of charge and discharge cycles and discharge capacity of
the lithium battery of each of Example 1, Comparative Example 1,
and Comparative Example 2 of the invention at high temperature.
DESCRIPTION OF THE EMBODIMENTS
[0023] In the present specification, a range represented by "a
numerical value to another numerical value" is a schematic
representation for avoiding listing all of the numerical values in
the range in the specification. Therefore, the recitation of a
specific numerical range covers any numerical value in the
numerical range and a smaller numerical range defined by any
numerical value in the numerical range, as is the case with any
numerical value and the smaller numerical range in the
specification.
[0024] Moreover, in the present specification, skeleton formulas
are sometimes used to represent compound structures. Such
representation can omit carbon atoms, hydrogen atoms, and
carbon-hydrogen bonds. Of course, structural formulas with clear
illustrations of functional groups are definitive.
[0025] To prepare an oligomer-polymer that can be applied in the
cathode material of a lithium battery such that the lithium battery
still has good performance in a high-temperature environment, the
invention provides an oligomer-polymer that can achieve the
advantages above. In the following, embodiments are provided as
examples of actual implementation of the invention.
[0026] An embodiment of the invention provides an oligomer-polymer.
The oligomer-polymer is obtained by the polymerization reaction of
a compound containing an ethylenically unsaturated group and a
nucleophile compound, wherein the nucleophile compound includes the
compound shown in formula 1:
##STR00004##
[0027] In the present embodiment, the compound containing an
ethylenically unsaturated group includes, for instance, a
maleimide-based compound. Specifically, in the present embodiment,
the maleimide-based compound includes, for instance, monomaleimide
or bismaleimide. The monomaleimide is, for instance, selected from
the group consisting of unsubstituted maleimide, N-phenylmaleimide,
N-(o-methylphenyl)-maleimide, N-(m-methylphenyl)-maleimide,
N-(p-methylphenyl)-maleimide, N-cyclohexylmaleimide,
maleimidophenol, maleimidobenzocyclobutene, phosphorus-containing
maleimide, phosphonate-containing maleimide, siloxane-containing
maleimide, N-(4-tetrahydropyranyl-oxyphenyl)maleimide, and
2,6-xylylmaleimide; and the bismaleimide can have the structure
represented by formula I:
##STR00005##
wherein R.sub.1 includes: --(CH.sub.2).sub.2--,
--(CH.sub.2).sub.6--, --(CH.sub.2).sub.8--,
--(CH.sub.2).sub.12--,
##STR00006##
[0028] Moreover, in the present embodiment, the oligomer-polymer is
obtained by the addition polymerization reaction of the compound
containing an ethylenically unsaturated group and the nucleophile
compound via a Michael addition reaction. In other words, at this
point, the Michael addition reaction occurs between oxygen atoms of
the hydroxyl group in the compound shown in formula 1 and C--C
double bonds in the compound containing an ethylenically
unsaturated group. Specifically, the addition polymerization
reaction of the compound containing an ethylenically unsaturated
group and the nucleophile compound can be performed using any known
method.
[0029] In an embodiment, a method of performing the addition
polymerization reaction on the compound containing an ethylenically
unsaturated group and the nucleophile compound includes, for
instance: dissolving the compound containing an ethylenically
unsaturated group and the nucleophile compound in a solvent and
reacting the mixture at a temperature of 25.degree. C. to
200.degree. C. for 0.5 hours to 5 hours.
[0030] In the above steps, the mole ratio of the compound
containing an ethylenically unsaturated group and the nucleophile
compound is between 2:1 and 1:1. If the mole ratio of the compound
containing an ethylenically unsaturated group and the nucleophile
compound is less than 2:1, then the Michael addition reactivity is
poor; and if the mole ratio of the compound containing an
ethylenically unsaturated group and the nucleophile compound is
higher than 1:1, then an excessive amount of the nucleophile
compound remains such that an electrochemical side reaction
occurs.
[0031] The solvent can be an organic solvent, such as (but not
limited to)N-methyl pyrollidone (NMP), dimethylformamide (DMF),
dimethyl sulfoxide (DMSO), dimethylacetamide (DMAC), or a
combination thereof.
[0032] In another embodiment, the addition polymerization reaction
can also be performed in the presence of a catalyst, i.e., the
compound containing an ethylenically unsaturated group, the
nucleophile compound, and the catalyst are dissolved in the solvent
for the reaction. At this point, the reaction temperature is, for
instance, between, 25.degree. C. and 80.degree. C., the reaction
time is, for instance, between 0.5 hours and 2 hours, the catalyst
is, for instance, triethylamine or dibenzyl trithiocarbonate
(DBTTC), and the content of the catalyst is, for instance, 1 part
by weight to 10 parts by weight.
[0033] Moreover, in the present embodiment, the nucleophile
compound can further include the compound shown in formula 2
below:
##STR00007##
Specifically, the compound shown in formula 1 and the compound
shown in formula 2 are tautomers, and the compound shown in formula
2 tends to be converted into the compound shown in formula 1 when
the pH is greater than 6. As a result, as described above, when the
oligomer-polymer is prepared by a Michael addition reaction under
alkaline conditions, the nucleophile compound must include the
compound shown in formula 1.
[0034] More specifically, since the pH of the reaction environment
affects the balance between the compound shown in formula 1 and the
compound shown in formula 2, the ratio of the compound shown in
formula 1 and the compound shown in formula 2 in the nucleophile
compound changes with the pH. For instance, in comparison to weak
alkaline reaction conditions, under strong alkaline reaction
conditions, the proportion of the compound shown in formula 1 in
the nucleophile compound is higher, even the compound shown in
formula 2 may not even exist. In other words, in the present
embodiment, the oligomer-polymer can be obtained by the
polymerization reaction of the compound containing an ethylenically
unsaturated group and the compound shown in formula 1, or the
oligomer-polymer can be obtained by the polymerization reaction of
the compound containing an ethylenically unsaturated group, the
compound shown in formula 1, and the compound shown in formula 2,
and the ratio of the compound shown in formula 1 and the compound
shown in formula 2 changes with the pH.
[0035] In an embodiment, the oligomer-polymer is prepared under the
following conditions: the compound containing an ethylenically
unsaturated group, the nucleophile compound, and the triethylamine
catalyst are dissolved in an N-methylpyrrolidone solvent, and the
mixture is reacted at a temperature of 30.degree. C. to 50.degree.
C. for 0.5 hours to 2 hours. At this point, since
N-methylpyrrolidone is weakly alkaline and triethylamine is a weak
alkaline catalyst, the nucleophile compound includes the compound
shown in formula 1 and the compound shown in formula 2, and the
synthesis mole ratio is between 2:1 and 1:1. From another
perspective, a Michael addition reaction is performed on oxygen
atoms of the hydroxyl group in the compound shown in formula 1 and
nitrogen atoms of secondary amine in the compound shown in formula
2 with C--C double bonds in the compound containing an
ethylenically unsaturated group.
[0036] It should be mentioned that, in the present embodiment, the
oligomer-polymer has a hyperbranched structure. "Hyperbranched
structure" is a structure formed by adding the nucleophile compound
on the C--C double bonds of the compound containing an
ethylenically unsaturated group such that the C--C double bonds of
the compound containing an ethylenically unsaturated group can be
opened up allowing the two carbon atoms or one of the two carbon
atoms to bond with other atoms for branching and ordering
polymerization reactions by using the compound containing an
ethylenically unsaturated group as an architecture matrix during
the addition polymerization reaction of the compound containing an
ethylenically unsaturated group and the nucleophile compound (i.e.,
the compound shown in formula 1, or the compound shown in formula 1
and the compound shown in formula 2).
[0037] It should be mentioned that, the oligomer-polymer obtained
by the polymerization reaction of the compound containing an
ethylenically unsaturated group and the nucleophile compound (i.e.,
the compound shown in formula 1, or the compound shown in formula 1
and the compound shown in formula 2) can be applied in the cathode
material of a lithium battery. More specifically, the
oligomer-polymer forms a protective layer on the surface of the
cathode material, and the protective layer can effectively prevent
damage to the cathode structure in a high-temperature environment,
with the reason being that the oligomer-polymer has a hyperbranched
structure as described above, and therefore the oligomer-polymer
can form a stable complex with the metal oxide in a regular cathode
material and be distributed on the surface thereof. Moreover, since
the oligomer-polymer has a rigid chemical structure, the resulting
protective layer can have high thermal stability. In this way, the
lithium battery having the cathode material including the
oligomer-polymer can still have good capacitance, battery
efficiency and safety in a high-temperature environment, and the
cycle life of the battery can be improved.
[0038] Another embodiment of the invention provides a lithium
battery including the oligomer-polymer in any one of the above
embodiments. In the following, description is provided with
reference to FIG. 1.
[0039] FIG. 1 is a cross-sectional schematic of a lithium battery
according to an embodiment of the invention.
[0040] Referring to FIG. 1, a lithium battery 100 includes an anode
102, a cathode 104, an isolation film 106, an electrolyte solution
108, and a package structure 112.
[0041] In the present embodiment, the anode 102 includes an anode
metal foil 102a and an anode material 102b, wherein the anode
material 102b is disposed on the anode metal foil 102a through
coating or sputtering. The anode metal foil 102a is, for instance,
a copper foil, an aluminum foil, a nickel foil, or a
high-conductivity stainless steel foil. The anode material 102b is,
for instance, carbide or metal lithium. The carbide used as the
anode material 102b is, for instance, carbon powder, graphite,
carbon fiber, carbon nanotube, graphene, or a mixture thereof.
However, in other embodiments, the anode 102 can also only include
the anode material 102b.
[0042] The cathode 104 and the anode 102 are separately disposed.
The cathode 104 includes a cathode metal foil 104a and a cathode
material 104b, wherein the cathode material 104b is disposed on the
cathode metal foil 104a through coating. The cathode metal foil
104a is, for instance, a copper foil, an aluminum foil, a nickel
foil, or a high-conductivity stainless steel foil. The cathode
material 104b includes the oligomer-polymer in any one of the above
embodiments and a lithium-mixed transition metal oxide.
Specifically, in the present embodiment, the oligomer-polymer is
used as a cathode material additive. The lithium-mixed transition
metal oxide is, for instance, LiAl.sub.0.05Co.sub.0.95O,
LiMnO.sub.2, LiMn.sub.2O.sub.4, LiCoO.sub.2,
Li.sub.2Cr.sub.2O.sub.7, Li.sub.2CrO.sub.4, LiNiO.sub.2,
LiFeO.sub.2, LiNi.sub.xCo.sub.1-xO.sub.2,
Li[NiLi.sub.(1-2x)/3Mn.sub.(2-x)/3]O.sub.2, LiFePO.sub.4,
LiMn.sub.0.5Ni.sub.0.5O.sub.2,
LiMn.sub.1/3Co.sub.1/3Ni.sub.1/3O.sub.2,
LiMc.sub.0.5Mn.sub.1.5O.sub.4, or a combination thereof, where
0<x<1 and Mc is a divalent metal. Moreover, in the present
embodiment, based on a total weight of 100 parts by weight of the
cathode material 104b, the content of the oligomer-polymer is 0.1
parts by weight to 10 parts by weight, preferably 0.1 parts by
weight to 5 parts by weight; and the content of the lithium-mixed
transition metal oxide is, for instance, 80 parts by weight to 92
parts by weight, preferably 85 parts by weight to 90 parts by
weight. If the content of the oligomer-polymer is less than 0.1
parts by weight, then the battery safety characteristic is not
significant; and if the content of the oligomer-polymer is higher
than 10 parts by weight, then the battery cycle life is poor.
[0043] Moreover, in an embodiment, the lithium battery 100 can
further include a polymer binder, and the polymer binder reacts
with the anode 102 and/or the cathode 104 to increase the
mechanical properties of the electrode(s). Specifically, the anode
material 102b can be adhered to the anode metal foil 102a through
the polymer binder, and the cathode material 104b can be adhered to
the cathode metal foil 104a through the polymer binder. The polymer
binder is, for instance, polyvinylidene difluoride (PVDF),
styrene-butadiene rubber (SBR), polyamide, melamine resin, or a
combination thereof.
[0044] The isolation film 106 is disposed between the anode 102 and
the cathode 104, and the isolation film 106, the anode 102, and the
cathode 104 define a housing region 110. The material of the
isolation film 106 is, for instance, an insulating material, and
the insulating material can be polyethylene (PE), polypropylene
(PP), or a multilayer composite structure of the materials, such as
PE/PP/PE.
[0045] In the present embodiment, the electrolyte solution 108 is
disposed in the housing region 110, and the electrolyte solution
108 includes an organic solvent, a lithium salt, and an additive.
In particular, the content of the organic solvent in the
electrolyte solution 108 is 55 wt % to 90 wt %, the content of the
lithium salt in the electrolyte solution 108 is 10 wt % to 35 wt %,
and the content of the additive in the electrolyte solution 108 is
0.05 wt % to 10 wt %. However, in other embodiments, the
electrolyte solution 108 may also not include an additive.
[0046] The organic solvent is, for instance, .gamma.-butyrolactone
(GBL), ethylene carbonate (EC), propylene carbonate (PC), diethyl
carbonate (DEC), propyl acetate (PA), dimethyl carbonate (DMC),
ethylmethyl carbonate (EMC), or a combination thereof.
[0047] The lithium salt is, for instance, LiPF.sub.6, LiBF.sub.4,
LiAsF.sub.6, LiSbF.sub.6, LiClO.sub.4, LiAlCl.sub.4, LiGaCl.sub.4,
LiNO.sub.3, LiC(SO.sub.2CF.sub.3).sub.3,
LiN(SO.sub.2CF.sub.3).sub.2, LiSCN, LiO.sub.3SCF.sub.2CF.sub.3,
LiC.sub.6F.sub.5SO.sub.3, LiO.sub.2CCF.sub.3, LiSO.sub.3F,
LiB(C.sub.6H.sub.5).sub.4, LiCF.sub.3SO.sub.3, or a combination
thereof.
[0048] The additive includes, for instance, monomaleimide,
polymaleimide, bismaleimide, polybismaleimide, a copolymer of
bismaleimide and monomaleimide, vinylene carbonate (VC), or a
mixture thereof. The monomaleimide is, for instance, selected from
the group consisting of unsubstituted maleimide, N-phenylmaleimide,
N-(o-methylphenyl)-maleimide, N-(m-methylphenyl)-maleimide,
N-(p-methylphenyl)-maleimide, N-cyclohexylmaleimide,
maleimidophenol, maleimidobenzocyclobutene, phosphorus-containing
maleimide, phosphonate-containing maleimide, siloxane-containing
maleimide, N-(4-tetrahydropyranyl-oxyphenyl)maleimide, and
2,6-xylylmaleimide. The bismaleimide can have the structure
represented by formula I above.
[0049] The package structure 112 is used to package the anode 102,
the cathode 104, and the electrolyte solution 108. The material of
the package structure 112 is, for instance, aluminum foil.
[0050] It should be mentioned that, the cathode material 104b of
the lithium battery 100 includes the oligomer-polymer and the
lithium-mixed transition metal oxide, and therefore, as described
above, the oligomer-polymer having a hyperbranched structure can
form a stable complex with the lithium-mixed transition metal oxide
and form the protective layer on the surface of the lithium-mixed
transition metal oxide. Moreover, since the oligomer-polymer has
the rigid chemical structure, the resulting protective layer can
have high thermal stability. In this way, the lithium battery 100
having the cathode material 104b including the oligomer-polymer can
still have good capacitance, safety, and battery efficiency in a
high-temperature environment, and the cycle life of the battery can
be improved.
[0051] Moreover, the cathode 104 having the protective layer in the
lithium battery 100 can be formed by adding the oligomer-polymer in
the cathode material in a current battery manufacturing process.
Therefore, the capacitance, battery efficiency, and charge and
discharge cycle life of the lithium battery 100 can be effectively
maintained at high temperature without modifying any battery
design, electrode material and electrolyte solution.
[0052] Example 1 and Comparative Examples 1 to 2 are provided below
to more specifically describe the invention. Although the following
examples are described, the materials used and the amount and ratio
thereof, as well as handling details and handling process . . .
etc., can be suitably modified without exceeding the scope of the
invention. Accordingly, restrictive interpretation should not be
made to the invention based on the experiments described below.
Example 1
Preparation of Anode
[0053] Metal lithium was cut into a suitable shape and inserted
directly to form the anode.
Preparation of Cathode
[0054] 40 parts by weight (0.5 moles) of a compound containing an
ethylenically unsaturated group, 50 parts by weight (0.5 moles) of
a nucleophile compound, and 10 parts by weight of a triethylamine
catalyst were added in a suitable amount of an N-methylpyrrolidone
solvent, and the components were mixed and stirred to react for 2
hours at a temperature of 25.degree. C. to prepare the
oligomer-polymer of Example 1, wherein the structural formula of
the compound containing an ethylenically unsaturated group is as
shown in formula I:
##STR00008##
[0055] formula I, R.sub.1 in formula I is
##STR00009##
and a suitable synthesis mole ratio of the compound shown in
formula 1 and the compound shown in formula 2 in the nucleophile
compound is about 3:2.
[0056] Next, 90 parts by weight of LiAl.sub.0.05Co.sub.0.95O.sub.2,
5 parts by weight of polyvinyl difluoride (PVDF), and 5 parts by
weight of acetylene black (conductive powder) were uniformly mixed
in the N-methylpyrrolidone solvent. Next, 0.5 parts by weight of
the oligomer-polymer of Example 1 was added to the mixed solution
to form the cathode material. Then, after the material was coated
on an aluminum foil, the aluminum foil with the material coated
thereon was dried, compressed, and then cut to form the
cathode.
Preparation of Electrolyte Solution
[0057] LiPF.sub.6 was dissolved in a mixed solution of propylene
carbonate (PC), ethylene carbonate (EC), and diethyl carbonate
(DEC) (volume ratio: PC/EC/DEC=2/3/5) to prepare an electrolyte
solution having a concentration of 1 M, wherein the mixed solution
was used as an organic solvent in the electrolyte solution, and
LiPF.sub.6 was used as lithium salt in the electrolyte
solution.
Manufacture of Lithium Battery
[0058] After polypropylene was used as the isolation film to
isolate the anode and the cathode and define the housing region,
the electrolyte solution was added in the housing region between
the anode and the cathode. Lastly, the above structure was sealed
with a package structure to complete the manufacture of the lithium
battery of Example 1.
Comparative Example 1
Preparation of Anode
[0059] The anode of Comparative Example 1 was prepared based on the
same preparation process as Example 1.
Preparation of Cathode
[0060] 40 parts by weight (0.5 moles) of a maleimide-based
compound, 50 parts by weight (0.5 moles) of a barbituric acid
compound, and 10 parts by weight of a triethylamine catalyst were
added in a suitable amount of an N-methylpyrrolidone solvent, and
the components were mixed and stirred to react for 3 hours at a
temperature of 80.degree. C. to prepare the oligomer-polymer of
Comparative Example 1, wherein the structural formula of the
maleimide-based compound is as shown in formula I:
##STR00010##
R.sub.1 in formula I is
##STR00011##
the structural formula of the barbituric acid compound is as shown
in formula II below, and R.sub.2 and R.sub.3 in formula II are
H:
##STR00012##
[0061] Next, 90 parts by weight of LiAl.sub.0.05Co.sub.0.95O.sub.2,
5 parts by weight of polyvinyl difluoride (PVDF), and 5 parts by
weight of acetylene black (conductive powder) were uniformly mixed
in the N-methylpyrrolidone solvent. Next, 0.5 parts by weight of
the oligomer-polymer of Comparative Example 1 was added in the
mixed solution to form the cathode material. Then, after the
material was coated on an aluminum foil, the aluminum foil with the
material coated thereon was dried, compressed, and then cut to form
the cathode.
Preparation of Electrolyte Solution
[0062] The electrolyte solution of Comparative Example 1 was
prepared based on the same preparation process as Example 1.
Manufacture of Lithium Battery
[0063] The lithium battery of Comparative Example 1 was made
according to a similar manufacturing process as Example 1, and the
difference thereof is only in that: in the lithium battery of
Comparative Example 1, the cathode material includes the
oligomer-polymer of Comparative Example 1; and in the lithium
battery of Example 1, the cathode material includes the
oligomer-polymer of Example 1.
Comparative Example 2
Preparation of Anode
[0064] The anode of Comparative Example 2 was prepared based on the
same preparation process as Example 1.
Preparation of Cathode
[0065] The cathode of Comparative Example 2 was prepared according
to a similar preparation process as Example 1, and the difference
thereof is only in that: no cathode material additive was added in
the cathode material of Comparative Example 2.
Preparation of Electrolyte Solution
[0066] The electrolyte solution of Comparative Example 2 was
prepared based on the same preparation process as Example 1.
Manufacture of Lithium Battery
[0067] The lithium battery of Comparative Example 2 was made
according to a similar manufacturing process as Example 1, and the
difference thereof is only in that: in the lithium battery of
Comparative Example 2, no cathode material additive was added in
the cathode material; and in the lithium battery of Example 1, the
cathode material includes the oligomer-polymer of Example 1.
[0068] Next, a charge and discharge performance test was performed
on the lithium batteries of Example 1 and Comparative Examples 1 to
2, and the measurement results thereof are shown in Table 1 and
FIG. 2. A charge and discharge cycle test was performed on the
lithium batteries of Example 1 and Comparative Example 2, and the
measurement results thereof are shown in Table 2 and FIG. 3.
Charge and Discharge Performance Test
[0069] The first cycle of charge and discharge was performed on the
lithium batteries of Example 1 and Comparative Examples 1 to 2 at
fixed current/voltage at room temperature (30.degree. C.) using a
potentiostat (made by Biologic Corporation, model: VMP3). First,
the batteries were charged to 4.8 V with a constant current of 0.1
C until the current was less than or equal to 0.02 C. Then, the
batteries were discharged to the cut-off voltage 2 V with a
constant current of 0.1 C. The discharge capacity and
irreversibility ratio of the lithium batteries of Example 1 and
Comparative Examples 1 to 2 are recorded in Table 1 below. FIG. 2
shows a curve diagram illustrating the relationship between
capacitance and voltage of the lithium battery of each of Example 1
and Comparative Examples 1 and 2 of the invention at room
temperature.
TABLE-US-00001 TABLE 1 Discharge capacity Irreversibility ratio
(mAh/g) (%) Example 1 225.1 86.4 Comparative 220.8 83.5 Example 1
Comparative 219.5 84.5 Example 2
[0070] It can be known from Table 1 and FIG. 2 that, in comparison
to the lithium batteries of Comparative Examples 1 to 2, the
lithium battery of Example 1 has higher discharge capacity and a
similar irreversibility ratio. The results indicate that by
preparing the cathode using the oligomer-polymer of the invention
obtained by the polymerization reaction of the compound containing
an ethylenically unsaturated group and the nucleophile compound
including the compound shown in formula 1, not only are battery
characteristics not affected, overall energy density of the battery
is also increased.
Charge and Discharge Cycle Test
[0071] The lithium battery of each of Example 1 and Comparative
Example 2 was charged and discharged at fixed current/voltage at
room temperature (30.degree. C.) using a potentiostat (made by
Biologic Corporation, model: VMP3). First, the charge and discharge
cycle was repeated 20 times according to the following conditions:
the battery was charged to 4.8 V at a fixed current of 0.1 C until
the current was less than or equal to 0.02 C, and then the battery
was discharged to the cutoff voltage (3 V) at a fixed current of
0.1 C. After the 20 charge and discharge cycles were performed, the
charge and discharge cycle was repeated 10 times according to the
following conditions: the battery was charged to 4.8 V at a fixed
current of 0.1 C until the current was less than or equal to 0.02
C, and then the battery was discharged to the cutoff voltage (3 V)
at a fixed current of 0.2 C. Lastly, the charge and discharge cycle
was repeated again 10 times according to the following conditions:
the battery was charged to 4.8 V at a fixed current of 0.1 C until
the current was less than or equal to 0.02 C, and then the battery
was discharged to the cutoff voltage (3 V) at a fixed current of
0.5 C to complete a total of 40 charge and discharge cycles. The
discharge capacity of the lithium battery of each of Example 1 and
Comparative Example 2 of the 40th cycle and the retention rate of
the discharge capacity after 40 charge and discharge cycles are
recorded in Table 2 below. FIG. 3 shows a diagram illustrating the
relationship between the number of charge and discharge cycles and
discharge capacity of the lithium battery of each of Example 1 and
Comparative Example 2 of the invention at room temperature.
TABLE-US-00002 TABLE 2 Discharge capacity of 40th cycle Retention
rate (mAh/g) (%) Example 1 144.6 74.9 Comparative 132.0 81.8
Example 2
[0072] It can be known from Table 2 and FIG. 3 that, in comparison
to the lithium battery of Comparative Example 2, after 40 charge
and discharge cycles at room temperature, the lithium battery of
Example 1 has higher discharge capacity and capacitance retention
rate. The results indicate that by preparing the cathode using the
oligomer-polymer of the invention obtained by the polymerization
reaction of the compound containing an ethylenically unsaturated
group and the nucleophile compound including the compound shown in
formula 1, the cathode can still have good structural stability
after 40 charge and discharge cycles at room temperature, such that
the lithium battery can have good capacitance, battery efficiency,
and charge and discharge cycle life. Moreover, the results also
prove that the oligomer-polymer of the invention can indeed be
accepted by the current lithium battery and improve the safety of
the battery.
[0073] Moreover, the lithium battery of each of Example 1,
Comparative Example 1, and Comparative Example 2 was charged and
discharged at fixed current/voltage at high temperature (55.degree.
C.) using a potentiostat (made by Biologic Corporation, model:
VMP3). The charge and discharge cycle was repeated 10 times
according to the following conditions: the battery was charged to
4.8 V at a fixed current of 0.1 C until the current was less than
or equal to 0.02 C, and then the battery was discharged to the
cutoff voltage (3 V) at a fixed current of 0.1 C. The discharge
capacity of the lithium battery of each of Example 1, Comparative
Example 1, and Comparative Example 2 of the 10th cycle and the
retention rate of the discharge capacity after 10 charge and
discharge cycles are recorded in Table 3 below. FIG. 4 shows a
diagram illustrating the relationship between the number of charge
and discharge cycles and discharge capacity of the lithium battery
of each of Example 1, Comparative Example 1, and Comparative
Example 2 of the invention at high temperature.
TABLE-US-00003 TABLE 3 Discharge capacity of 10th cycle Retention
rate (mAh/g) (%) Example 1 172.3 98.9 Comparative 166.0 96.1
Example 1 Comparative 172.9 97.2 Example 2
[0074] It can be known from Table 3 and FIG. 4 that, in comparison
to the lithium batteries of Comparative Example 1 and Comparative
Example 2, after 10 charge and discharge cycles in a
high-temperature environment, the lithium battery of Example 1 has
higher capacitance retention rate, and after 10 charge and
discharge cycles in a high-temperature environment, the lithium
battery of Example 1 still has good discharge capacity. The results
indicate that by preparing the cathode using the oligomer-polymer
of the invention obtained by the polymerization reaction of the
compound containing an ethylenically unsaturated group and the
nucleophile compound including the compound shown in formula 1, the
cathode can still have good structural stability in a
high-temperature environment, such that the lithium battery can
have good capacitance, battery efficiency, and charge and discharge
cycle life. Moreover, the results also prove that the
oligomer-polymer of the invention can indeed be accepted by the
current lithium battery and improve the safety of the battery.
[0075] Although the invention has been described with reference to
the above embodiments, it will be apparent to one of ordinary skill
in the art that modifications to the described embodiments may be
made without departing from the spirit of the invention.
Accordingly, the scope of the invention is defined by the attached
claims not by the above detailed descriptions.
* * * * *