【TECHNICAL FIELD】5
Cross Citation with Related Application(s)
This application claims the benefit of Korean Patent Application No. 10-2020-0139305 filed on October 26, 2020 and Korean Patent Application No. 10-2021-0137513 filed on October 15, 2021 in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference in their entirety. 10
The present disclosure relates to an electrode for secondary battery, a secondary battery including same, and a method of manufacturing an electrode, and more particularly, to an electrode for secondary battery having improved tensile strength and resistance reduction effect, a secondary battery including same, and a method of manufacturing an electrode.
15
【BACKGROUND】
Along with the technology development and increased demand for mobile devices, demand for secondary batteries as energy sources has been rapidly increasing. Among these secondary batteries, a lithium secondary battery having high energy density and a high voltage, a long cycle lifespan, and a low self-discharge rate is commercially available and widely used. 20
In particular, a secondary battery has attracted considerable attention as an energy source for power-driven devices, such as an electric bicycle, an electric vehicle, and a hybrid electric vehicle, as well as an energy source for mobile devices, such as a mobile phone, a digital camera, a laptop computer and a wearable device.
In addition, as interest in environmental issues grows, studies are frequently conducted 25 on an electric vehicle, a hybrid electric vehicle, etc. which can replace a vehicle using fossil fuels such as a gasoline vehicle and a diesel vehicle, which are one of the main causes of air pollution. Although a nickel metal hydride secondary battery is mainly used as a power source for the
3
electric vehicle and the hybrid electric vehicle, research on the use of a lithium secondary battery having high energy density is actively being conducted, a part of which are in the commercialization stage.
Conventional electrodes for secondary batteries are manufactured in a wet manner. However, when the electrode is manufactured in a wet manner, a heat treatment process at a high 5 temperature is essentially required, and there is a risk that the metal oxide may be damaged. Therefore, there is a growing need to develop an electrode manufactured in a dry manner.
【DETAILED DESCRIPTION OF THE INVENTION】
【Technical Problem】
It is an object of the present disclosure to provide an electrode for secondary battery 10 having improved tensile strength and resistance reduction effect, a secondary battery including same, and a method of manufacturing an electrode.
The objects of the present disclosure are not limited to the aforementioned objects, and other objects which are not described herein should be clearly understood by those skilled in the art from the following detailed description and the accompanying drawings. 15
【Technical Solution】
According to an embodiment of the present disclosure, there is provided an electrode for secondary battery comprising: an electrode current collector; and an electrode layer located on the electrode current collector, wherein the electrode layer comprises an electrode composition in which an active material, a conductive material, and a binder are dry-mixed, wherein the binder 20 comprises a first binder and a second binder, with the first binder and the second binder being different from each other, and wherein the second binder is attached to the surface of the first binder.
A glass transition temperature (Tg) of the second binder may be larger than a glass transition temperature (Tg) of the first binder. 25
The glass transition temperature (Tg) of the first binder may be 15 degrees Celsius or more and 100 degrees Celsius or less, and the glass transition temperature (Tg) of the second binder may be 25 degrees Celsius or more and 115 degrees Celsius or less. A content of the
4
binder may be 0.51% by weight or more and 11.99% by weight or less based on the total weight of the electrode composition.
A content ratio of the first binder and the second binder may have a ratio of 0.1:10 to 10:0.1.
The first binder may include polytetrafluoroethylene (PTFE), and the second binder may 5 include an acrylic polymer material.
The active material may include at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium copper oxide (Li2CuO2), vanadium oxide, a Ni-site type lithium nickel oxide, lithium manganese composite oxide, lithium manganese composite oxide having a spinel structure, LiMn2O4 in which a part of Li in formula 10 is substituted with an alkaline earth metal ion, a disulfide compound; Fe2(MoO4)3, and lithium manganese oxide (LMO). The electrode composition is manufactured into a freestanding film, and the freestanding film may be attached onto the electrode current collector.
The freestanding film may have a tensile strength of 5kgf/cm2 or more and 50kgf/cm2 or less. 15
According to another embodiment of the present disclosure, there is provided a method of manufacturing an electrode for secondary battery, the method comprising the steps of: dry-mixing an active material, a conductive material and a binder to prepare a mixture; applying a shearing force to the mixture to prepare an electrode composition; manufacturing a freestanding film with the electrode composition; and attaching the freestanding film onto the electrode 20 current collector to form an electrode for secondary battery, wherein the binder comprises a first binder and a second binder, with the first binder and the second binder being different from each other, and wherein the second binder is attached to the surface of the first binder.
A glass transition temperature (Tg) of the second binder may be larger than a glass transition temperature (Tg) of the first binder. 25
The glass transition temperature (Tg) of the first binder may be 15 degrees Celsius or more and 100 degrees Celsius or less, and the glass transition temperature (Tg) of the second binder may be 25 degrees Celsius or more and 115 degrees Celsius or less. The step of dry-
5
mixing an active material, a conductive material and a binder to prepare a mixture may be performed at room temperature, and the step of applying a shearing force to the mixture to prepare an electrode composition may be performed at a temperature of 100 degrees Celsius or more.
The content of the binder may be 0.51% by weight or more and 11.99% by weight or 5 less based on the total weight of the electrode composition.
A content ratio of the first binder and the second binder may have a ratio of 0.1:10 to 10:0.1.
The first binder may include polytetrafluoroethylene (PTFE), and the second binder may include an acrylic polymer material. 10
The active material may include at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium copper oxide (Li2CuO2), vanadium oxide, a Ni-site type lithium nickel oxide, lithium manganese composite oxide, lithium manganese composite oxide having a spinel structure, LiMn2O4 in which a part of Li in formula is substituted with an alkaline earth metal ion, a disulfide compound; Fe2(MoO4)3, and lithium 15 manganese oxide (LMO).
According to yet another embodiment of the present disclosure, there is provided a secondary battery comprising the above-mentioned electrode for secondary battery.
【Advantageous Effects】
According to embodiments of the present disclosure, an electrode for secondary battery and 20 a secondary battery including the same are manufactured by using electrode compositions including mutually different binders, whereby the tensile strength of the electrode can be improved, and the resistance reduction effect of the secondary battery including the electrode can be improved.
The effects of the present disclosure are not limited to the effects mentioned above and 25 additional other effects not described above will be clearly understood from the description of the appended claims by those skilled in the art.
【BRIEF DESCRIPTION OF THE DRAWINGS】
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Fig. 1 is a diagram showing an electrode composition of an electrode for secondary battery according to an embodiment of the disclosure;
Fig. 2 is a flowchart showing a method of manufacturing an electrode for secondary battery according to an embodiment of the present disclosure;
Fig. 3 is a graph for comparing a tensile strength and an initial discharge capacity 5 according to the binder content of an electrode for secondary battery, in Examples and Comparative Examples of the present disclosure;
Fig. 4 is a graph for comparing a tensile strength and an initial discharge capacity according to the content ratio of the first binder and the second binder of an electrode for secondary battery, in Examples and Comparative Examples of the present disclosure; and 10
Fig. 5 is a graph for comparing a tensile strength and an initial discharge capacity according to a glass transition temperature of the first binder and the second binder of an electrode for secondary battery, in Examples and Comparative Examples of the present disclosure.

【Claim 1】
An electrode for secondary battery comprising:
an electrode current collector; and
an electrode layer located on the electrode current collector, 5
wherein the electrode layer comprises an electrode composition in which an active material, a conductive material, and a binder are dry-mixed,
wherein the binder comprises a first binder and a second binder, with the first binder and the second binder being different from each other, and
wherein the second binder is attached to the surface of the first binder. 10
【Claim 2】
The electrode for secondary battery according to claim 1, wherein:
a glass transition temperature (Tg) of the second binder is larger than a glass transition temperature (Tg) of the first binder.
【Claim 3】15
The electrode for secondary battery according to claim 2, wherein:
the glass transition temperature (Tg) of the first binder is 15 degrees Celsius or more and 100 degrees Celsius or less, and
the glass transition temperature (Tg) of the second binder is 25 degrees Celsius or more and 115 degrees Celsius or less. 20
【Claim 4】
The electrode for secondary battery according to claim 1, wherein:
a content of the binder is 0.51% by weight or more and 11.99% by weight or less based on the total weight of the electrode composition.
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【Claim 5】
The electrode for secondary battery according to claim 1, wherein:
a content ratio of the first binder and the second binder has a ratio of 0.1:10 to 10:0.1.
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【Claim 6】
The electrode for secondary battery according to claim 1, wherein:
the first binder comprises polytetrafluoroethylene (PTFE), and
the second binder comprises an acrylic polymer material.
【Claim 7】5
The electrode for secondary battery according to claim 1, wherein:
the active material comprises at least one selected from the group consisting of lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium copper oxide (Li2CuO2), vanadium oxide, a Ni-site type lithium nickel oxide, lithium manganese composite oxide, lithium manganese composite oxide having a spinel structure, LiMn2O4 in which a part of Li in formula 10 is substituted with an alkaline earth metal ion, a disulfide compound; Fe2(MoO4)3, and lithium manganese oxide (LMO).
【Claim 8】
The electrode for secondary battery according to claim 1, wherein:
the electrode composition is manufactured into a freestanding film, and 15
the freestanding film is attached onto the electrode current collector.
【Claim 9】
The electrode for secondary battery according to claim 8, wherein:
the freestanding film has a tensile strength of 5kgf/cm2 or more and 50kgf/cm2 or less.
【Claim 10】20
A method of manufacturing an electrode for secondary battery, the method comprising the steps of:
dry-mixing an active material, a conductive material and a binder to prepare a mixture;
applying a shearing force to the mixture to prepare an electrode composition;
manufacturing a freestanding film with the electrode composition; and 25
attaching the freestanding film onto the electrode current collector to form an electrode for secondary battery,
wherein the binder comprises a first binder and a second binder, with the first binder and
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the second binder being different from each other, and
wherein the second binder is attached to the surface of the first binder.
【Claim 11】
The method of manufacturing an electrode for secondary battery according to claim 10, wherein: 5
a glass transition temperature (Tg) of the second binder is larger than a glass transition temperature (Tg) of the first binder.
【Claim 12】
The method of manufacturing an electrode for secondary battery according to claim 11, wherein: 10
the glass transition temperature (Tg) of the first binder is 15 degrees Celsius or more and 100 degrees Celsius or less, and
the glass transition temperature (Tg) of the second binder is 25 degrees Celsius or more and 115 degrees Celsius or less.
【Claim 13】15
The method of manufacturing an electrode for secondary battery according to claim 10, wherein:
the step of dry-mixing an active material, a conductive material and a binder to prepare a mixture is performed at room temperature, and
the step of applying a shearing force to the mixture to prepare an electrode composition 20 is performed at a temperature of 100 degrees Celsius or more.
【Claim 14】
The method of manufacturing an electrode for secondary battery according to claim 10, wherein:
the sum of the contents of the first binder and the second binder is 0.51% by weight or 25 more and 11.99% by weight or less based on the total weight of the electrode composition.
【Claim 15】
The method of manufacturing an electrode for secondary battery according to claim 10,
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wherein:
a content ratio of the first binder and the second binder has a ratio of 0.1:10 to 10:0.1.
【Claim 16】
The method of manufacturing an electrode for secondary battery according to claim 10,
5 wherein:
the first binder comprises polytetrafluoroethylene (PTFE), and
the second binder comprises an acrylic polymer material.
【Claim 17】
The method of manufacturing an electrode for secondary battery according to claim 10,
10 wherein:
the active material comprises at least one selected from the group consisting of lithium
cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium copper oxide (Li2CuO2),
vanadium oxide, a Ni-site type lithium nickel oxide, lithium manganese composite oxide, lithium
manganese composite oxide having a spinel structure, LiMn2O4 in which a part of Li in formula
15 is substituted with an alkaline earth metal ion, a disulfide compound; Fe2(MoO4)3, and lithium
manganese oxide (LMO).
【Claim 18】
A secondary battery comprising the electrode for secondary battery as set forth in claim
1.