Anode composition, anode for lithium secondary battery, comprising same, lithium secondary battery, and method for preparing anode composition

Abstract

The present invention relates to an anode composition, an anode for a lithium secondary battery, comprising same, a lithium secondary battery, and a method for preparing the anode composition, the anode composition comprising a silicon oxide represented by SiOx (0<x<2), graphite, and an anode conductive material, wherein the graphite comprises natural graphite and artificial graphite, and the BET specific surface area values of the silicon oxide represented by SiOx (0<x<2), the natural graphite, and the artificial graphite are amounts increasing in the order of artificial graphite < natural graphite < silicon oxide represented by SiOx (0<x<2).

Description

Negative electrode composition, negative electrode for lithium secondary battery including same, lithium secondary battery and method for producing negative electrode composition

[0001] This application claims the benefit of the filing dates of Korean Patent Application No. 10-2023-0117771, filed with the Korean Intellectual Property Office on September 5, 2023, and Korean Patent Application No. 10-2024-0120175, filed with the Korean Intellectual Property Office on September 4, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to a negative electrode composition, a negative electrode for a lithium secondary battery including the same, a lithium secondary battery, and a method for manufacturing the negative electrode composition.

[0003] The recent rapid proliferation of battery-powered electronic devices, including mobile phones, laptops, electric vehicles, power tools, and vacuum cleaners, has led to a rapid increase in demand for compact, lightweight, and relatively high-capacity and / or high-output secondary batteries. In particular, lithium secondary batteries, with their lightweight design and high energy density, are attracting attention as power sources for electronic devices. Accordingly, active research and development efforts are underway to improve the performance of lithium secondary batteries.

[0004] Lithium secondary batteries produce electrical energy through oxidation and reduction reactions when lithium ions are inserted / deintercalated between the positive and negative electrodes, which are made of active materials capable of intercalating and deintercalating lithium ions, while charging an organic electrolyte or polymer electrolyte between them.

[0005] As a cathode active material constituting the cathode of a lithium secondary battery, a metal oxide such as LiCoO2, LiMnO2, LiMn2O4 or LiNiO2 is used, and as a cathode active material constituting the anode, a carbon-based material such as metal lithium, graphite or activated carbon, or silicon oxide (SiO x ) are being used. Among the above negative active materials, metallic lithium was mainly used in the early days, but as the charge and discharge cycle progressed, lithium atoms grew on the surface of metallic lithium, damaging the separator and destroying the battery. Therefore, carbon-based materials are mainly used recently.

[0006] Graphite is mainly used as an anode active material for lithium secondary batteries, but since graphite has a small capacity per unit mass of 372 mAh / g, it is difficult to increase the capacity of lithium secondary batteries. Accordingly, in order to increase the capacity of lithium secondary batteries, non-carbonaceous anode materials such as silicon, tin, and their oxides, which have a higher energy density than graphite, are being developed. However, in the case of these non-carbonaceous anode materials, although the capacity is large, the initial efficiency is low, so the lithium consumption during the initial charge and discharge is large, and there is a problem that the irreversible capacity loss is large.

[0007] In particular, silicon-based active materials undergo excessive volume changes during battery operation. This, in turn, reduces battery life. Therefore, there is a need to develop an anode that can effectively improve battery life characteristics while using silicon-based anode active materials.

[0008] [Prior Art Literature]

[0009] [Patent Document]

[0010] Korean Patent Publication No. 10-2021-0070933

[0011] The inventors of the present invention have discovered that, in a lithium secondary battery designed within a limited space, optimal battery performance can be achieved by selecting a specific combination of the types of active materials and conductive materials constituting the negative electrode composition, the content of each component, and the BET specific surface area value.

[0012] One embodiment of the present invention is a negative electrode composition comprising a silicon-based active material; graphite and a negative electrode conductive material, wherein the graphite includes natural graphite and artificial graphite, and the silicon-based active material is SiOx(0 <x<2)로 표시되는 산화실리콘을 포함하고, 상기 SiOx(0<x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 BET 비표면적 값은 인조흑연 < 천연흑연 < SiOx(0<x<2)로 표시되는 산화실리콘 순으로 큰 것인 음극 조성물을 제공한다.

[0013] Another embodiment of the present invention provides a method for manufacturing a lithium secondary battery and a negative electrode composition including the negative electrode.

[0014] Another embodiment of the present invention provides a battery module and a battery pack including the lithium secondary battery.

[0015] In the case of a negative electrode composition according to one embodiment of the present invention, in order to manufacture a high-capacity battery, a silicon-based active material, which is a high-capacity material, is used, and the SiOx(0 <x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 인조흑연의 BET 비표면적의 상호관계를 만족하여, 기존 이차 전지의 수명 저하를 개선하고, 급속 충전이 가능하며, 전극 접착력이 우수한 특징을 가질 수 있다.

[0016] In addition, SiOx(0) included in the above-mentioned cathode composition <x<2)로 표시되는 산화실리콘, 흑연 및 도전재로 단일벽 탄소 나노 튜브(SWCNT)를 함께 사용함으로써, 음극 활물질 입자 간의 도전성 경로를 개선시켜 전지의 용량, 효율 및 수명 성능이 향상될 수 있다.

[0017] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0018] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0019] The terminology used herein is for the purpose of describing exemplary embodiments only and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

[0020] In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0021] Furthermore, when we say that a part of a layer or the like is "above" or "on" another part, this includes not only cases where it is "directly above" that part, but also cases where there is another part in between. Conversely, when we say that a part is "directly above" another part, it means that there is no other part in between. Furthermore, saying that a part is "above" or "on" a reference part means that it is located above or below that reference part, and does not necessarily mean that it is located "above" or "on" in the opposite direction of gravity.

[0022] In this specification, "specific surface area" is measured by the BET method, and specifically, it can be measured by removing gas (degassing) from a measurement target at 130°C for 2 hours and performing N2 absorption / desorption at 77K using BET measuring equipment (BEL-SORP-mini, Nippon Bell). That is, the BET specific surface area in this specification can mean the specific surface area of ​​the particle itself measured by the above measurement method.

[0023] In this specification, the average length or diameter of the challenge material can be measured using SEM or TEM.

[0024] In this specification, "pore size" may mean the size of the pores of the particle itself, and may be measured by a calculation formula according to the BJH (Barrett-Joyer-Halenda) method using a nitrogen adsorption method. Specifically, the pore area according to the pore size was derived using the BELSORP-mini Ⅱ model of BEL Japan, and then the size of the pore with the largest pore area was used as a representative. The BJH method can be used, and the plot of the measured values ​​is such that the X-axis represents the pore diameter (Dp / nm) and the Y-axis represents dVp / dDp (cm 3 g -1 nm -1 )am.

[0025] In this specification, "pore volume" may mean the volume of the pores of the particle itself, and may be measured by a calculation formula according to the absorption / desorption isotherm method using the nitrogen adsorption method. Specifically, after deriving a N2 adsorption / desorption isotherm graph using the BELSORP-mini Ⅱ model of BEL Japan, the volume at the highest point of P / P0 (close to 1) in adsorption was used as a representative. The absorption / desorption isotherm method can be used, and the plot of the measured value is such that the X-axis is pressure (P / P0), and the Y-axis is Va / cm 3 (STP)g -1 am.

[0026]

[0027] <Cathode composition>

[0028] An anode composition according to one embodiment of the present application is an anode composition including a silicon-based active material; graphite and a cathode conductive material, wherein the graphite includes natural graphite and artificial graphite, and the silicon-based active material is SiOx(0 <x<2)로 표시되는 산화실리콘을 포함하고, 상기 SiOx(0<x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 BET 비표면적 값은 인조흑연 < 천연흑연 < SiOx(0<x<2)로 표시되는 산화실리콘 순으로 큰 것이다.

[0029] The above SiOx(0 <x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 인조흑연의 BET 비표면적의 상호관계를 만족하는 경우, 이차 전지의 수명 저하를 개선하고, 급속 충전이 가능하며, 전극 접착력이 우수하다.

[0030] In particular, the lithium secondary battery according to the present application comprises SiOx(0) among silicon-based active materials. <x<2)로 표시되는 산화실리콘을 사용하는 것을 특징으로 한다. 구체적으로 다른 실리콘계 활물질(예를 들어, Si / C)과 대비하였을 때, 상기와 같은 활물질을 사용하는 경우 전극 품질, 즉 전극에 대한 접착력이 향상되는 특징을 갖게 된다.

[0031] In one embodiment of the present application, the SiOx(0 <x<2)로 표시되는 산화실리콘은 마그네슘 금속 또는 리튬 금속으로 도핑될 수 있다.

[0032] The SiOx(0) according to the present application <x<2)로 표시되는 산화실리콘은 도핑하지 않고 사용될 수 있으며, 또한 상기와 같이 도핑되어 사용될 수 있고, 도핑하는 경우 산화실리콘에 미리 실리케이트를 형성하여 초기 충전 시 비가역 용량이 감소하여 셀의 에너지 밀도를 증가시키는 효과를 나타낼 수 있다.

[0033] According to one embodiment of the present application, the SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 천연흑연의 BET 비표면적보다 1 m 2 / g to 9 m 2 / g is big.

[0034] The above SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 천연흑연의 BET 비표면적보다 1.2 m 2 / g or more, 1.5 m 2 / g or more, 1.7 m 2 / g or more, or 1.9 m 2 / g or more. The above SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 천연흑연의 BET 비표면적보다 8.7 m 2 / g or less, 8.4 m 2 / g or less, 8.2 m 2 / g or less, or 8 m 2 / g is larger than or equal to.

[0035] According to one embodiment of the present application, the SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 인조흑연의 BET 비표면적보다 2 m 2 / g to 10 m 2 / g is big.

[0036] The above SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 인조흑연의 BET 비표면적보다 2.2 m 2 / g or more, 2.5 m 2 / g or more, 2.7 m 2 / g or more, or 2.9 m 2 / g or larger.

[0037] The above SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 인조흑연의 BET 비표면적보다 내지 9.7 m 2 / g or less, 9.4 m 2 / g or less, 9.2 m 2 / g or less, or 9 m 2 / g is larger than or equal to.

[0038] According to one embodiment of the present application, the BET specific surface area of ​​the natural graphite is 0.1 m higher than the BET specific surface area of ​​the artificial graphite. 2 / g to 2 m 2 / g is big.

[0039] The BET specific surface area of ​​the above natural graphite is 0.2 m higher than that of the above artificial graphite. 2 / g or more, or 0.3 m 2 / g or more. The BET surface area of ​​the above natural graphite is 1.9 m larger than that of the above artificial graphite. 2 / g or less, 1.8 m 2 / g or less, or 1.7 m 2 / g is larger than or equal to.

[0040] Natural graphite has a BET surface area of ​​1.5 m 2 / g or more than 3.5 m 2 / g or less, which can improve electrode adhesion. Artificial graphite and SiOx(0 <x<2)로 표시되는 산화실리콘은 급속 충전 및 수명성능에 영향을 주며, BET 비표면적이 각각 0.1 m 2 / g or more than 2.5 m 2 / g or less, 3 m 2 / g or more than 15 m 2 / g or less.

[0041] If the BET specific surface area of ​​artificial graphite is larger than that of natural graphite, a large amount of binder in the electrode may be consumed when manufacturing an electrode with the above negative electrode composition, which may reduce the electrode adhesion. In addition, SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적이 천연흑연의 BET 비표면적보다 작은 경우, SiOx(0<x<2)로 표시되는 산화실리콘 내 리튬의 삽입 및 / 또는 탈리가 어려워져 수명 성능 및 급속충전 성능이 저하될 수 있다.

[0042] According to an additional embodiment of the present application, the negative electrode composition includes graphite, and the graphite may include natural graphite and artificial graphite.

[0043] For example, the natural graphite may satisfy the relationship between the content and the specific surface area. Furthermore, more specifically, the natural graphite may have a sphericity of 0.9 or higher and satisfy the above conditions.

[0044] In this specification, the degree of sphericity may be a value obtained by dividing the circumference of a circle having the same area as the projected image when a particle is projected by the perimeter of the projected image, and may be specifically expressed by the following mathematical formula 1. The degree of sphericity may be obtained from an SEM image, or alternatively, may be measured using a particle shape analyzer, such as a Malvern sysmex FPIA3000 particle shape analyzer. In addition, the crystal size can be confirmed through XRD analysis.

[0045] [Mathematical Formula 1]

[0046] Sphericity = Circumference of a circle with the same area as the image projected on the particle / Perimeter of the projected image

[0047] The above natural graphite refers to graphite that occurs naturally, and examples include scaled graphite, scaly graphite, or soil graphite. The above natural graphite has the advantages of being abundant, low in price, having high theoretical capacity and compaction density, and being capable of achieving high output.

[0048] The above natural graphite can be applied by selecting those that satisfy the sphericity by checking the particle shape through SEM and checking through a particle shape analyzer.

[0049] For example, the artificial graphite may satisfy the relationship between the content and the specific surface area. In addition, more specifically, the artificial graphite may satisfy the above conditions while having a sphericity of 0.9 or less.

[0050] The above artificial graphite can be applied by selecting those that satisfy the sphericity by checking the particle shape through SEM and checking through a particle shape analyzer.

[0051] According to an additional embodiment of the present application, the negative electrode conductive material may include a single-walled carbon nanotube (SWCNT). The single-walled carbon nanotube (SWCNT) refers to a tube-shaped carbon structure composed of a single carbon layer. When the conductive material in the negative electrode composition includes the single-walled carbon nanotube (SWCNT), the charge / discharge capacity and / or life performance of the battery may be improved. Specifically, the single-walled carbon nanotube (SWCNT) well connects the conductive path between particles, thereby preventing the loss of the conductive path due to swelling of the silicon-based negative electrode active material described above. Consequently, when the single-walled carbon nanotube (SWCNT) is included, the life performance of the battery may be improved.

[0052] In this specification, the length of a carbon nanotube means the length of a major axis passing through the center of a unit of the carbon nanotube, and the diameter of a carbon nanotube means the length of a minor axis passing through the center of the unit and perpendicular to the major axis.

[0053] The average length of the single-walled carbon nanotube (SWCNT) may be 0.1 μm to 50 μm, specifically 0.5 μm to 25 μm or 0.5 μm to 20 μm. More specifically, it may be 5 μm to 15 μm. The lower limit of the average length may be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm or 8 μm, and the upper limit may be 50 μm, 30 μm, 25 μm, 20 μm, 15 μm, 14 μm, 13 μm, 12 μm, 11 μm or 10 μm.

[0054] Single-walled carbon nanotubes (SWCNTs) are SiOx(0) having the above characteristics, such as electrical conductivity, strength, and <x<2)로 표시되는 산화실리콘 및 흑연과 함께 사용하는 경우, 음극 활물질 입자 간 거리만큼의 탄소 나노 튜브의 길이가 확보되므로 입자 간 도전성 경로(conductive path)의 연결이 더욱 용이해져 음극의 전기전도성, 강도 및 / 또는 전해액 보관 유지성이 향상될 수 있다. 반면, 탄소 나노 튜브의 길이가 짧으면 효율적으로 도전성 경로를 형성하기 어렵기 때문에 전기 전도성이 저하될 우려가 있고 탄소 나노 튜브의 길이가 지나치게 길면 분산성이 저하될 우려가 있다.

[0055] The average length of the above single-walled carbon nanotubes (SWCNTs) can be calculated as the average value of the results observed using SEM.

[0056] The average diameter of the single-walled carbon nanotube (SWCNT) may be 1 nm to 20 nm, specifically 1.5 nm to 15 nm. More specifically, it may be 1.5 nm to 5 nm. The lower limit of the average diameter may be 1 nm, 1.5 nm, or 2 nm, and the upper limit may be 20 nm, 18 nm, 16 nm, 14 nm, 12 nm, 10 nm, 8 nm, 6 nm, or 4 nm.

[0057] Single-walled carbon nanotubes (SWCNTs) that satisfy the above range have flexible characteristics, so even when physically damaged, the contact between negative electrode active material particles is not easily broken. On the other hand, if the diameter of the carbon nanotubes (SWCNTs) is excessively large, there is a concern that the electrode density may decrease, and if the diameter of the carbon nanotubes (SWCNTs) is excessively small, dispersion may be difficult, which may lower the processability of the dispersion liquid production.

[0058] The average diameter of the above single-walled carbon nanotubes (SWCNTs) can be calculated as an average value observed by TEM.

[0059] The BET surface area of ​​the above single-walled carbon nanotube is 200 m 2 / g to 2,000 m 2 / g can be, specifically 250 m 2 / g to 1,500 m 2 / g. When single-walled carbon nanotubes (SWCNTs) satisfying the above range are used, even with a small amount of conductive material, dispersion is easy, and there is an effect of effectively connecting the particles.

[0060] The single-walled carbon nanotube (SWCNT) may be included in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the cathode composition, and specifically, may be included in an amount of 0.01 to 4 parts by weight, 0.01 to 3 parts by weight, 0.01 to 2 parts by weight, 0.01 to 1 part by weight, or 0.05 to 0.5 parts by weight.

[0061] When the above range is satisfied, SiOx(0 <x<2)로 표시되는 산화실리콘 및 흑연을 포함하는 실리콘계 음극 활물질 입자 간의 도전성 경로(conductive path)의 연결을 용이하게 하면서, 높은 비표면적에 의한 전해액 부반응을 최소화할 수 있는 효과가 있다.

[0062] According to an additional embodiment of the present application, the SiOx(0 <x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 BET 비표면적 값은 인조흑연 < 천연흑연 < SiOx(0<x<2)로 표시되는 산화실리콘 순일 수 있다.

[0063] For example, the specific surface area is measured by the BET method, and specifically, the specific surface area can be measured by degassing the measurement target at 130°C for 2 hours and performing N2 absorption / desorption at 77K using a BET measurement device (BEL-SORP-mini, Nippon Bell). That is, the BET specific surface area in the present specification may mean the specific surface area of ​​the particle itself measured by the above measurement method.

[0064] In one example, the cathode conductive material may include single-walled carbon nanotubes (SWCNTs).

[0065] In the case of a negative electrode composition according to an embodiment of the present application, in order to manufacture a high-capacity battery, a silicon-based active material, which is a high-capacity material, is used, and SiOx(0) having the above-mentioned content <x<2)로 표시되는 산화실리콘, 천연흑연, 인조흑연 및 단일벽 탄소 나노 튜브(SWCNT)를 포함하고, 상기 SiOx(0<x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 인조흑연의 BET 비표면적의 상호관계를 만족하여, 기존 이차 전지의 수명 저하를 개선하고, 급속 충전이 가능하며, 전극 접착력이 우수한 특징을 가질 수 있다.

[0066] In addition, SiOx(0) included in the cathode composition having the above-mentioned content <x<2)로 표시되는 산화실리콘, 흑연 및 도전재로서 단일벽 탄소 나노 튜브(SWCNT)를 함께 사용함으로써, 음극 활물질 입자 간의 도전성 경로를 개선시켜 전지의 용량, 효율 및 수명 성능이 향상될 수 있다.

[0067] In one embodiment of the present application, the SiOx(0 <x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 기공 부피(total pore V.)는 인조흑연 ≤ 천연흑연 ≤ SiOx(0<x<2)로 표시되는 산화실리콘 순으로 큰 것인 음극 조성물을 제공한다.

[0068] According to an additional embodiment of the present application, SiOx(0) in the cathode composition <x<2)로 표시되는 산화실리콘, 천연흑연 및 인조흑연은 기공을 포함하는 것일 수 있다.

[0069] For example, the volume of the pores may refer to the volume of the pores of the particle itself, and may be measured by a calculation formula based on the absorption / desorption isotherm method using the nitrogen adsorption method. Specifically, the N2 adsorption / desorption isotherm graph was derived using the BELSORP-mini ± model of BEL Japan, and the volume at the highest point of P / P0 (close to 1) in adsorption was used as a representative. The absorption / desorption isotherm method can be used, and the plot of the measured values ​​is such that the X-axis is pressure (P / P0), and the Y-axis is Va / cm 3 (STP)g -1 am.

[0070] As an example, the SiOx(0 <x<2)로 표시되는 산화실리콘의 기공 부피(total pore V.)는 7 cm 3 / g or more, the pore volume (total pore V.) of the above natural graphite is 3 cm 3 / g to 7 cm 3 / g and the pore volume (total pore V.) of the above artificial graphite is 3 cm 3 / g can be less.

[0071] The above SiOx(0 <x<2)로 표시되는 산화실리콘의 기공 부피는 상기 천연흑연의 기공 부피보다 1 cm 3 / g to 8 cm 3 / g can be large.

[0072] The above SiOx(0 <x<2)로 표시되는 산화실리콘의 기공 부피는 상기 천연흑연의 기공 부피와 같을 수 있다.

[0073] The above SiOx(0 <x<2)로 표시되는 산화실리콘의 기공 부피는 상기 인조흑연의 기공 부피보다 4 cm 3 / g to 11 cm 3 / g is big.

[0074] The pore volume of the above natural graphite is 1 cm larger than the pore volume of the above artificial graphite. 3 / g to 6 cm 3 / g can be large.

[0075] The pore volume of the above natural graphite may be the same as the pore volume of the above artificial graphite.

[0076] The above SiOx(0 <x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 기공 부피(total pore V.)가 상기 범위를 만족하는 경우, 이차 전지의 수명 저하를 개선하고, 급속 충전이 가능하며, 전극 접착력이 우수한 특징을 가질 수 있다.

[0077] In one embodiment of the present application, the number of pores (pore intensity) having a size of 2 nm or more and 200 nm or less in the negative electrode composition is artificial graphite ≤ natural graphite ≤ SiOx(0 <x<2)로 표시되는 산화실리콘 순으로 많은 것인 음극 조성물을 제공한다.

[0078] For example, the size of the pores may refer to the size of the pores of the particle itself, and may be measured by a calculation formula based on the BJH (Barrett-Joyer-Halenda) method using a nitrogen adsorption method. Specifically, the pore area according to the pore size was derived using the BELSORP-mini Ⅱ model of BEL Japan, and the size of the pore with the largest pore area was used as a representative. The BJH method can be used, and the plot of the measured values ​​is such that the X-axis represents the pore diameter (Dp / nm), and the Y-axis represents dVp / dDp (cm 3 g -1 nm -1 )am.

[0079] When the above range is satisfied, the secondary battery can have the characteristics of improving the lifespan reduction, enabling rapid charging, and having excellent electrode adhesion.

[0080] In one embodiment of the present application, the natural graphite has a BET specific surface area of ​​1.5 m 2 / g or more than 3.5 m 2 / g or less, and the artificial graphite has a BET surface area of ​​0.1 m 2 / g or more than 2.5 m 2 / g or less.

[0081] The above natural graphite has a BET surface area of ​​1.5 m 2 / g or more than 3.5 m 2 / g or less, 1.5 m 2 / g or more than 3.3 m 2 / g or less, 1.5 m 2 / g or more than 3 m 2 / g or less, 1.5 m 2 / g or more 2.8 m 2 / g or less, or 1.5 m 2 / g or more than 2.5 m 2 / g can be less.

[0082] The above artificial graphite has a BET surface area of ​​0.1 m 2 / g or more 2.2 m 2 / g or less, 0.1 m 2 / g or more 2 m 2 / g or less, 0.1 m 2 / g or more than 1.8 m 2 / g or less, 0.1 m 2 / g or more than 1.5 m 2 / g or less, 0.3 m 2 / g or more than 2.5 m 2 / g can be less.

[0083] When the above natural graphite and artificial graphite satisfy the above BET specific surface area range, the negative electrode composition is SiOx(0 <x<2)로 표시되는 산화실리콘 외의 비표면적이 상이한 2종의 흑연을 포함함으로써, 음극 활물질로써 상기 SiOx(0<x<2)로 표시되는 산화실리콘을 사용함에 따른 전지 용량의 증가 및 높은 C-rate에서 출력 특성이 우수한 특성을 가질 수 있으면서도, 실리콘계 입자의 큰 부피변화에 의해 발생할 수 있는 음극 및 이차 전지의 수명 저하 문제를 개선할 수 있다.

[0084] Natural graphite can improve electrode adhesion within the above BET specific surface area range, and artificial graphite can affect rapid charging and life performance within the above BET specific surface area range. In addition, when artificial graphite has a larger BET specific surface area than natural graphite, a large amount of binder within the electrode is consumed when manufacturing the electrode using the above negative electrode composition, which may reduce electrode adhesion.

[0085] In one embodiment of the present application, the negative electrode conductive material includes single-walled carbon nanotubes (SWCNTs), and SiOx(0) in the negative electrode composition <x<2)로 표시되는 산화실리콘, 흑연 및 단일벽 탄소 나노 튜브의 함량의 합계 100 중량부 기준 상기 SiOx(0<x<2)로 표시되는 산화실리콘은 0.5 중량부 내지 50 중량부; 상기 흑연은 45 중량부 내지 99 중량부; 및 상기 단일벽 탄소 나노 튜브(SWCNT)는 0.01 중량부 내지 5 중량부를 포함하며, 상기 흑연 100 중량부 기준 상기 천연흑연은 10 중량부 내지 70 중량부; 및 상기 인조흑연은 30 중량부 내지 90 중량부를 포함하는 것인 음극 조성물을 제공한다.

[0086] According to an additional embodiment of the present application, the cathode composition comprises SiOx(0 <x<2)로 표시되는 산화실리콘; 흑연 및 음극 도전재를 포함하고, 상기 흑연은 천연흑연 및 인조흑연을 포함하며, 상기 음극 도전재는 단일벽 탄소 나노 튜브(SWCNT)를 포함할 수 있다.

[0087] According to an additional embodiment of the present application, among the cathode compositions, SiOx(0 <x<2)로 표시되는 산화실리콘, 흑연 및 단일벽 탄소 나노 튜브의 함량의 합계 100 중량부 기준 상기 SiOx(0<x<2)로 표시되는 산화실리콘은 0.5 중량부 내지 50 중량부; 상기 흑연은 45 중량부 내지 99 중량부; 및 상기 단일벽 탄소 나노 튜브(SWCNT)는 0.01 중량부 내지 5 중량부를 포함할 수 있다.

[0088] According to one example, among the above cathode compositions, SiOx(0 <x<2)로 표시되는 산화실리콘, 흑연 및 단일벽 탄소 나노 튜브의 함량의 합계 100 중량부 기준 상기 SiOx(0<x<2)로 표시되는 산화실리콘은 1 중량부 내지 40 중량부, 2 중량부 내지 30 중량부, 3 중량부 내지 20 중량부, 4 중량부 내지 10 중량부, 또는 5 중량부 내지 10 중량부일 수 있다. 상기 흑연은 50 중량부 내지 99 중량부, 55 중량부 내지 99 중량부, 60 중량부 내지 99 중량부, 65 중량부 내지 99 중량부, 70 중량부 내지 99 중량부, 또는 75 중량부 내지 95 중량부일 수 있다. 상기 단일벽 탄소 나노 튜브(SWCNT)는 0.01 중량부 내지 4 중량부, 0.01 중량부 내지 3 중량부, 0.01 중량부 내지 2 중량부, 0.01 중량부 내지 1 중량부, 0.05 중량부 내지 0.5 중량부일 수 있다.

[0089] According to an additional embodiment of the present application, the natural graphite may be included in an amount of 10 to 70 parts by weight based on 100 parts by weight of the graphite, and the artificial graphite may be included in an amount of 30 to 90 parts by weight.

[0090] According to an example, the natural graphite may be 11 to 68 parts by weight based on 100 parts by weight of the graphite, and the artificial graphite may be 32 to 89 parts by weight.

[0091] In the content range of the above cathode composition, in particular, the SiOx(0 <x<2)로 표시되는 산화실리콘의 함량 범위를 만족할 때 용량 특성이 개선될 수 있고, 상기 흑연의 함량 범위를 만족할 때 급속 충전 성능 및 음극 접착력이 개선될 수 있으며, 상기 단일벽 탄소 나노 튜브(SWCNT)의 함량 범위를 만족할 때 전지의 효율 및 수명 성능이 향상될 수 있다. 이에 이차 전지의 수명 저하를 개선하고, 충전 및 방전이 가능한 포인트가 많아져 높은 C-rate에서 출력 특성이 우수한 특징을 가질 수 있다.

[0092] In one embodiment of the present application, a negative electrode composition further comprising a binder is provided.

[0093] The above binder may serve to improve adhesion between negative electrode active material particles and adhesion between the negative electrode active material particles and the negative electrode current collector. The above binder may be a negative electrode binder. The above-mentioned negative electrode binder may be one known in the art, and non-limiting examples thereof include at least one selected from the group consisting of polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylidene fluoride, polyacrylonitrile, polymethylmethacrylate, polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, polyacrylic acid, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and a material in which hydrogens of these are substituted with Li, Na, Ca, etc., and may also include various copolymers thereof.

[0094] The binder may be included in an amount of 10% or less, and preferably 1% to 5%, based on 100 parts by weight of the negative electrode composition. For example, the binder may be included in an amount of 9% or less, 8% or less, 7% or less, 6% or less, or 5% or less, based on 100 parts by weight of the negative electrode composition. The binder may be included in an amount of 0.5% or more, or 1% or more, based on 100 parts by weight of the negative electrode composition.

[0095]

[0096] <Method for producing a cathode composition>

[0097] One embodiment of the present application is a method for producing a negative electrode composition, comprising the steps of: forming a first mixture by mixing a negative electrode conductive material and water; and forming a second mixture by mixing the mixture with a silicon-based active material and graphite, wherein the graphite includes natural graphite and artificial graphite, and the silicon-based active material includes SiOx(0 <x<2)로 표시되는 산화실리콘을 포함하고, 상기 SiOx(0<x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 BET 비표면적 값은 인조흑연 < 천연흑연 < SiOx(0<x<2)로 표시되는 산화실리콘 순으로 큰 것인 음극 조성물의 제조 방법을 제공한다.

[0098] According to an additional embodiment of the present application, the method for producing the negative electrode composition comprises adding the SiOx(0) to the negative electrode conductive material. <x<2)로 표시되는 산화실리콘 및 흑연을 함께 혼합하는 단계를 포함할 수 있다.

[0099] In one embodiment of the present application, the negative electrode conductive material includes single-walled carbon nanotubes (SWCNTs), and SiOx(0) in the negative electrode composition <x<2)로 표시되는 산화실리콘, 흑연 및 단일벽 탄소 나노 튜브의 함량의 합계 100 중량부 기준 상기 SiOx(0<x<2)로 표시되는 산화실리콘은 0.5 내지 50 중량부; 상기 흑연은 45 내지 99 중량부; 및 상기 단일벽 탄소 나노 튜브(SWCNT)는 0.01 내지 5 중량부를 포함하며, 상기 흑연 100 중량부 기준 상기 천연흑연은 10 내지 70 중량부; 및 상기 인조흑연은 30 내지 90 중량부를 포함하는 것인 음극 조성물의 제조 방법을 제공한다.

[0100] In one embodiment of the present application, the SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 천연흑연의 BET 비표면적보다 1m 2 / g to 9m 2 / g is large, and the above SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 인조흑연의 BET 비표면적보다 2m 2 / g to 10m 2 / g is large, and the BET surface area of ​​the natural graphite is 0.1 m larger than that of the artificial graphite. 2 / g to 2m 2 / g is big.

[0101] In one embodiment of the present application, the SiOx(0 <x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 BET 비표면적 및 기공 부피에 대한 내용은 상기 음극 조성물에 전술한 바와 동일하다.

[0102]

[0103] <Cathode>

[0104] One embodiment of the present application provides a negative electrode for a lithium secondary battery, including a current collector; and a negative electrode active material layer including the above-described negative electrode composition formed on one or both sides of the current collector.

[0105] According to a further embodiment of the present application, the current collector is a negative current collector, which is not particularly limited as long as it is conductive and does not cause a chemical change in the battery. For example, the current collector may be copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel whose surface is treated with carbon, nickel, titanium, silver, etc. Specifically, a transition metal that well adsorbs carbon, such as copper or nickel, may be used as the current collector. The thickness of the current collector may be 1 μm to 500 μm, but the thickness of the current collector is not limited thereto.

[0106] According to an additional embodiment of the present application, a negative electrode active material layer comprising the negative electrode composition according to the above-described embodiment can be formed on one or both sides of the current collector. According to an example, the thickness of the negative electrode active material layer can be 20 μm or more and 500 μm or less.

[0107] According to an additional embodiment of the present application, the negative electrode for the lithium secondary battery can be manufactured according to a conventional negative electrode manufacturing method. The SiOx(0 <x<2)로 표시되는 산화실리콘 및 흑연은 음극 활물질일 수 있다. 구체적으로, 상기한 음극 활물질, 음극 도전재 및 선택적으로, 바인더를 포함하는 음극 조성물을 집전체 상에 도포한 후, 건조 및 압연함으로써 제조될 수 있다. 이때 상기 음극 활물질, 음극 도전재 및 바인더의 종류 및 함량은 앞서 설명한 바와 같다.

[0108] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. One of these may be used alone or as a mixture of two or more. The amount of the solvent used is sufficient to dissolve or disperse the negative electrode active material, negative electrode conductive material, and binder in consideration of the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the negative electrode. Alternatively, the negative electrode may be manufactured by casting the negative electrode composition on a separate support, and then laminating the film obtained by peeling it from the support onto a current collector.

[0109]

[0110] Lithium secondary battery

[0111] One embodiment of the present application provides a lithium secondary battery including a positive electrode; an anode for a lithium secondary battery according to the above-described embodiment; and a separator provided between the positive electrode and the negative electrode.

[0112] According to an additional embodiment of the present application, the cathode is identical to the cathode according to the aforementioned embodiment. Since the cathode has been described above, a detailed description thereof will be omitted.

[0113] According to a further embodiment of the present application, the positive electrode includes a positive electrode current collector, and a positive electrode active material layer including a positive electrode composition formed on the positive electrode current collector.

[0114] According to one example, the positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector and including the positive electrode composition. The positive electrode composition may include a positive electrode active material.

[0115] In the above positive electrode, the positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 ㎛, and fine unevenness may be formed on the surface of the current collector to increase the adhesive strength of the positive electrode active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0116] In one example, the thickness of the negative electrode active material layer may be 20 μm or more and 500 μm or less, and the thickness of the positive electrode active material layer may be 90% to 110%, for example, 95% to 105%, of the thickness of the negative electrode active material layer. Additionally, their thicknesses may be the same.

[0117] The above positive electrode active material may be a commonly used positive electrode active material. Specifically, the positive electrode active material may be a layered compound such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or a compound substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; or a compound having the chemical formula Li 1+c1 Mn 2-c1 Lithium manganese oxides such as O4(0≤c1≤0.33), LiMnO3, LiMn2O3, LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, Cu2V2O7; chemical formula LiNi 1-c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and satisfies 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 Lithium manganese composite oxide represented by O2 (wherein M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and satisfies 0.01≤c3≤0.1) or Li2Mn3MO8 (wherein M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); LiMn2O4, etc., in which a part of Li in the chemical formula is replaced with an alkaline earth metal ion, but is not limited thereto. The positive electrode may be Li-metal.

[0118] The above-described positive electrode active material layer may include a positive electrode conductive material and a positive electrode binder together with the positive electrode active material described above.

[0119] At this time, the positive electrode conductive material is used to provide conductivity to the electrode, and in the battery to be constructed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskey such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like, and one of these may be used alone or a mixture of two or more may be used.

[0120] In addition, the positive electrode binder plays a role of improving the adhesion between positive electrode active material particles and the adhesiveness between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof.

[0121] According to an additional embodiment of the present application, the lithium secondary battery may include a separator provided between the positive electrode and the negative electrode.

[0122] The separator is used to separate the negative electrode and the positive electrode and to provide a passage for lithium ions. Any separator commonly used in secondary batteries can be used without any particular restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, a coated separator containing a ceramic component or a polymer material may be used to secure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0123] According to one embodiment of the present application, the lithium secondary battery may include an electrolyte.

[0124] The above electrolyte may include, but is not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0125] Specifically, the electrolyte may include a non-aqueous organic solvent and a metal salt.

[0126] As the above non-aqueous organic solvent, for example, an aprotic organic solvent such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylsulfoxide, 1,3-dioxolan, formamide, dimethylformamide, dioxolan, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxy methane, dioxolan derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl pyrropionate, ethyl propionate, etc. can be used.

[0127] In particular, among the above carbonate-based organic solvents, ethylene carbonate and propylene carbonate, which are cyclic carbonates, are high-viscosity organic solvents with high dielectric constants and thus can be preferably used because they easily dissociate lithium salts. In addition, when low-viscosity, low-dielectric constant linear carbonates such as dimethyl carbonate and diethyl carbonate are mixed and used in an appropriate ratio with these cyclic carbonates, an electrolyte with high electrical conductivity can be produced, so that they can be used even more preferably.

[0128] The metal salt may be a lithium salt, and the lithium salt is a substance that is easily dissolved in the non-aqueous electrolyte, for example, the anion of the lithium salt is F - , Cl - , I - , NO3 - , N(CN)2 - , BF4 - , ClO4 - , PF6 - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , CF3SO3 -, CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - One or more selected from the group consisting of may be used.

[0129] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery.

[0130] In one embodiment of the present application, the lithium secondary battery is a cylindrical battery.

[0131] For example, the cylindrical battery may mean that the battery itself has a cylindrical shape and includes an assembly including a positive electrode, a negative electrode, a separator, and an electrolyte, and may be specifically composed of a cylindrical can, a battery assembly provided inside the cylindrical can, and a top cap.

[0132] In one embodiment of the present application, a battery module including the lithium secondary battery is provided.

[0133] In one embodiment of the present application, a battery pack including a battery module according to the above-described embodiment is provided.

[0134] A further embodiment of the present invention provides a battery module including the aforementioned cylindrical battery as a unit cell and a battery pack including the same. The battery module and battery pack include the secondary battery having high capacity, high rate characteristics, and cycle characteristics, and thus can be used as a power source for medium- to large-sized devices selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems.

[0135] The lithium secondary battery according to the embodiments of the present invention stably exhibits excellent discharge capacity, output characteristics, and cycle performance, and therefore can be used as a power source for portable devices such as mobile phones, laptop computers, and digital cameras, as well as medium- to large-sized devices selected from the group consisting of electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, and power storage systems. For example, the battery module or battery pack can be used as a power source for any one or more medium- to large-sized devices selected from the group consisting of power tools; electric vehicles including electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems.

[0136] Hereinafter, preferred embodiments are presented to help understand the present invention, but the above embodiments are only illustrative of the present disclosure, and it is obvious to those skilled in the art that various changes and modifications are possible within the scope and technical idea of ​​the present disclosure, and it is natural that such changes and modifications fall within the scope of the appended patent claims.

[0137] <Examples and Comparative Examples>

[0138] <Example 1>

[0139] Manufacturing of cathode

[0140] SiOx(0) in the cathode composition <x<2)로 표시되는 산화실리콘; 흑연 및 음극 도전재의 함량의 합계 100 중량부를 기준으로, SiOx(0<x<2)로 표시되는 산화실리콘 10 중량부, 흑연 89.5 중량부(인조흑연: 천연흑연 = 89:11 중량비) 및 단일벽 탄소 나노 튜브 0.5 중량부를 포함하고, 음극 조성물 100 중량부 기준으로, 바인더로서 SBR(styrenebutadiene rubber) 1.15 중량부와 CMC(carboxymethyl cellulose) 1 중량부를 포함하며, 이에 더하여 분산제 0.09 중량부 및 단일벽 CNT 0.06 중량부를 포함하는 CNT선분산액을 포함하는 음극 조성물을 제조하였다. 이 때, 상기 조성물에서 인조흑연, 천연흑연 및 산화실리콘의 BET 비표면적은 각각 0.8 m 2 / g, 1.8 m 2 / g, 7 m 2 / g was manufactured.

[0141] That is, a single-wall carbon nanotube dispersion using distilled water as a dispersion medium and CMC (carboxymethyl cellulose) as a dispersant was mixed with silicon oxide, graphite, carboxymethyl cellulose (CMC) as a binder, and styrene butadiene rubber (SBR), stirred, and then distilled water was added to prepare a negative electrode composition (solid content = 50 parts by weight).

[0142] The above negative electrode composition was applied to a copper (Cu) metal thin film, which is a negative electrode current collector, with a thickness of 15 ㎛, and dried. The temperature of the circulating air at this time was 60°C. Subsequently, the negative electrode was rolled (roll pressed) and dried in a vacuum oven at 130°C for 12 hours, thereby manufacturing a negative electrode in which a negative electrode active material layer was disposed on the negative electrode current collector.

[0143] At this time, the weight of CMC added as a binder among the CMC: the weight of CMC added as a dispersant = 1.14:0.06. The average length of the single-walled carbon nanotube units in the negative active material layer was 10 μm, and the average diameter was 2 nm.

[0144]

[0145] <Examples 2 to 14>

[0146] Artificial graphite, natural graphite and SiOx(0) included in the cathode composition <x<2)로 표시되는 산화실리콘의 BET 비표면적, 및 음극 조성물 중 SiOx(0<x<2)로 표시되는 산화실리콘; 흑연 및 단일벽 탄소 나노 튜브의 함량의 합계 100 중량부 기준 각각의 중량비가 하기 표 1에 기재된 것을 제외하고는 실시예 1과 동일한 방법으로 음극을 제조하였다.

[0147]

[0148] <Comparative Examples 1 to 5>

[0149] An anode was manufactured in the same manner as in Example 1, except that the BET specific surface areas of artificial graphite, natural graphite, and silicon oxide included in the anode composition, and the weight ratios of silicon oxide, graphite, and single-walled carbon nanotubes in the anode composition based on 100 parts by weight of the total content are as shown in Table 1 below.

[0150]

[0151] The cathodes manufactured in the above examples and comparative examples are as shown in Table 1 below.

[0152]

[0153] No. Surface area (m 2 / g) Composition ratio (wt.%) (based on 100 parts by weight of silicon-based active material; total of graphite and negative electrode conductive material) Artificial graphite Natural graphite SiOx (0 <x<2)로 표시되는 산화실리콘천연흑연인조흑연SiOx(0<x<2)SWCNT도전재실시예 10.81.8710.579100.5실시예 20.31.8710.579100.5실시예 31.51.8710.579100.5실시예 40.81.5710.579100.5실시예 50.82.5710.579100.5실시예 60.81.8310.579100.5실시예 70.81.811.510.579100.5실시예 80.81.8760.529100.5실시예 90.81.8715.57950.5실시예 100.81.8710.9579100.05실시예 110.81.875.584100.5실시예 120.81.87089.5100.5실시예 130.86.5710.579100.5실시예 140.81.82.510.579100.5비교예 12.01.5710.579100.5비교예 22.03.6310.579100.5비교예 34.03.6310.579100.5비교예 40.81.8-20.57900.5비교예 50.81.8710.579100

[0154] The above specific surface area was measured using a BET measuring device (BEL-SORP-mini, Nippon Bell) by degassing at 130°C for 2 hours and performing N2 adsorption / desorption at 77 K.

[0155]

[0156] <Experimental Example>

[0157] A lithium secondary battery including the negative electrodes of the examples and comparative examples was manufactured.

[0158]

[0159] Life (capacity retention) characteristic evaluation

[0160] The manufactured battery was charged and discharged to evaluate the capacity retention rate, which is shown in Table 2 below.

[0161] The first and second cycles were charged and discharged at 0.1 C, and from the third cycle onwards, the charging and discharging was performed at 0.5 C. The 300th cycle was completed in a charged state (with lithium in the negative electrode).

[0162] Charging conditions: CC (constant current) / CV (constant voltage) (4.25V / 0.05C current cut-off)

[0163] Discharge conditions: CC (constant current) condition 2.5 V

[0164] The capacity retention rate was derived by the following calculations.

[0165] Capacity retention rate (%) = (100 discharge capacity / 1 discharge capacity) × 100

[0166]

[0167] Table 2 below shows the values ​​for energy density (based on Example 1, %) and capacity retention rate (300 cycles, %) of Examples 1 to 14 and Comparative Examples 1 to 5.

[0168]

[0169] Li-plating point evaluation

[0170] The manufactured negative electrode was cut into a 1.4875 ㎠ circular lithium (Li) metal film as the positive electrode. A porous polyethylene separator was interposed between the positive and negative electrodes, and 0.5 parts by weight of vinylene carbonate was dissolved in a mixed solution of methyl ethyl carbonate (EMC) and ethylene carbonate (EC) in a volume ratio of 7:3, and an electrolyte solution containing 1 M LiPF6 was injected to manufacture a lithium coin half-cell.

[0171]

[0172] After completing one cycle of charge and discharge, the Li-plating point was measured under 1.8 C charging conditions.

[0173] Charging conditions: CC (constant current) / CV (constant voltage) (5mV / 0.005C current cut-off)

[0174] Discharge conditions: CC (constant current) condition 1.5 V

[0175]

[0176] Electrode adhesion evaluation

[0177] For each manufactured negative electrode, the negative electrode was punched out to a size of 20 mm × 150 mm and fixed to the center of a slide glass using tape. Then, the negative electrode current collector was peeled off using a UTM, and the 180-degree peel strength was measured. The evaluation was determined by measuring the peel strength at least five times and taking the average value. The results are shown in Table 2 below.

[0178] Life (300 cycle %)Li plating time (3C, SOC %)Electrode adhesion (gf cm)Example 1948554Example 2958454Example 3938453Example 4948554Example 5928554Example 6948553Example 7918454Example 8928254Example 9958355Example 10938554Example 11928549Example 12948554Example 13928455Example 14928553Comparative Example 1817836Comparative Example 2786736Comparative Example 3807859Comparative Example 4766855Comparative Example 5728151

[0179] The negative electrode composition according to the present invention comprises a silicon-based active material; graphite and a negative electrode conductive material, wherein the graphite comprises natural graphite and artificial graphite, and the SiOx(0 <x<2)로 표시되는 산화실리콘, 천연흑연 및 인조흑연의 BET 비표면적 값은 인조흑연 < 천연흑연 < SiOx(0<x<2)로 표시되는 산화실리콘 순으로 큰 것이 특징이다. 상기 음극 조성물은 고용량의 전지를 제작하기 위해 고용량 소재인 실리콘계 활물질을 사용함에 있어, 상기 SiOx(0<x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 인조흑연의 BET 비표면적의 상호관계를 만족하여, 기존 이차 전지의 수명 저하를 개선하고, 급속 충전이 가능하며, 전극 접착력이 우수한 특징을 가질 수 있다. 특히, 본 발명의 음극 조성물은 고용량의 전지를 제작하기 위하여, 인조흑연 및 천연흑연의 BET 비표면적 뿐만 아니라, SiO의 BET 비표면적의 상호관계를 함께 만족하여, 전기화학적 관점에서 부반응을 제어하는 “최적점”에서 최적의 전지 성능을 구현할 수 있다.또한, 전술한 음극 조성물에 포함된 SiOx(0<x<2)로 표시되는 산화실리콘, 흑연 및 도전재로 단일벽 탄소 나노 튜브(SWCNT)를 함께 사용함으로써, 음극 활물질 입자 간의 도전성 경로를 개선시켜 전지의 용량, 효율 및 수명 성능이 향상될 수 있다.

[0180] Natural graphite has a BET surface area of ​​1.5 m 2 / g or more than 3.5 m 2 / g or less, which can improve electrode adhesion. Artificial graphite and SiOx(0 <x<2)로 표시되는 산화실리콘은 급속 충전 및 수명성능에 영향을 주며, BET 비표면적이 각각 0.1 m 2 / g or more than 2.5 m 2 / g or less, 3 m 2 / g or more than 15 m 2 / g or less.

[0181] If the BET surface area of ​​artificial graphite is larger than that of natural graphite, a large amount of binder in the electrode may be consumed when manufacturing an electrode with the above negative electrode composition, which may reduce the electrode adhesion. In addition, if the BET surface area of ​​silicon oxide is smaller than that of natural graphite, SiOx(0 <x<2)로 표시되는 산화실리콘 내 리튬의 삽입 및 / 또는 탈리가 어려워져 수명 성능 및 급속충전 성능이 저하될 수 있다.

[0182] Examples 1 to 14 show that the negative electrode compositions satisfying a specific surface area ratio are excellent in life performance, rapid charging, and electrode adhesion.

[0183] On the other hand, Comparative Example 1 does not satisfy the specific surface area ratio of the negative electrode composition used in the present invention, and since the BET specific surface area value of artificial graphite is larger than that of natural graphite, when manufacturing an electrode with the negative electrode composition, a large amount of binder in the electrode is consumed, which may reduce electrode adhesiveness and thus reduce life performance.

[0184] Comparative Example 2 does not satisfy the specific surface area ratio of the cathode composition used in the present invention, SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적이 천연흑연의 BET 비표면적보다 작아 산화실리콘 내 리튬의 삽입 및 / 또는 탈리가 어려워져 수명 성능 및 급속충전 성능이 저하될 수 있다.

[0185] Comparative Example 3 does not satisfy the specific surface area ratio of the negative electrode composition used in the present invention, particularly when the BET surface area relationship is reversed from that of the present invention. In this case as well, lithium insertion and / or de-insertion within the negative electrode may become difficult, resulting in reduced life performance and rapid charging performance.

[0186] Comparative Example 4 is SiOx(0 <x<2)로 표시되는 산화실리콘을 사용하지 않은 경우에 해당한다. 이 경우 전극의 두께가 증가하여, 급속 충전 성능이 저하되며, 또한 0.5C / 0.5C의 비교적 높은 C-rate 사이클 평가를 진행하였으며, 이 경우 급속 충전 성능의 저하로, 누적의 개념으로 볼 수 있는 수명 성능도 저하됨을 확인할 수 있었다.

[0187] Comparative Example 5 corresponds to a case where a negative electrode conductive material was not used for reference. In particular, when comparing the above examples with the comparative examples, this corresponds to a case where SWCNTs were not included as the negative electrode conductive material. The negative electrode of the present application requires a negative electrode conductive material such as a long SWCNT to secure a conductive path due to the silicon-based material being an insulator. However, Comparative Example 5 did not include a material capable of securing the conductive path, and thus, it was confirmed that the life performance was poor.

Claims

1. A negative electrode composition comprising a silicon-based active material, graphite, and a negative electrode conductive material, The above graphite includes natural graphite and artificial graphite, The above silicon-based active material is SiOx(0 <x<2)로 표시되는 산화실리콘을 포함하고, The above SiOx(0 <x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 BET 비표면적 값은 인조흑연 < 천연흑연 < SiOx(0<x<2)로 표시되는 산화실리콘 순으로 큰 것인 음극 조성물.

2. In claim 1, the SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 천연흑연의 BET 비표면적보다 1 m 2 / g to 9 m 2 / g Large negative electrode composition.

3. In claim 1, The above SiOx(0 <x<2)로 표시되는 산화실리콘은 마그네슘 금속 또는 리튬 금속으로 도핑된 것인 리튬이차전지.

4. In claim 1, the SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 인조흑연의 BET 비표면적보다 2 m 2 / g to 10 m 2 / g Large negative electrode composition.

5. In claim 1, the BET specific surface area of ​​the natural graphite is 0.1 m larger than the BET specific surface area of ​​the artificial graphite. 2 / g to 2 m 2 / g Large negative electrode composition.

6. In claim 1, the SiOx(0 <x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 기공 부피(total pore V.)는 인조흑연 ≤ 천연흑연 ≤ SiOx(0<x<2)로 표시되는 산화실리콘 순으로 큰 것인 음극 조성물.

7. In claim 1, the natural graphite has a BET surface area of ​​1.5 m 2 / g or more than 3.5 m 2 / g or less, and the artificial graphite has a BET surface area of ​​0.1 m 2 / g or more than 2.5 m 2 A cathode composition having a weight of / g or less.

8. In claim 1, the negative electrode conductive material comprises a single-walled carbon nanotube (SWCNT), Among the above cathode compositions, SiOx(0 <x<2)로 표시되는 산화실리콘, 흑연 및 단일벽 탄소 나노 튜브의 함량의 합계 100 중량부 기준 상기 SiOx(0<x<2)로 표시되는 산화실리콘은 0.5 중량부 내지 50 중량부; 상기 흑연은 45 중량부 내지 99 중량부; 및 상기 단일벽 탄소 나노 튜브(SWCNT)는 0.01 중량부 내지 5 중량부를 포함하며, A negative electrode composition comprising 10 to 70 parts by weight of the natural graphite and 30 to 90 parts by weight of the artificial graphite based on 100 parts by weight of the graphite.

9. A negative electrode composition according to claim 1, further comprising a binder.

10. A step of forming a first mixture by mixing a cathode conductive material and water; and A method for manufacturing a negative electrode composition, comprising a step of forming a second mixture by mixing the above mixture with a silicon-based active material and graphite, The above graphite includes natural graphite and artificial graphite, The above silicon-based active material is SiOx(0 <x<2)로 표시되는 산화실리콘을 포함하고, The above SiOx(0 <x<2)로 표시되는 산화실리콘, 상기 천연흑연 및 상기 인조흑연의 BET 비표면적 값은 인조흑연 < 천연흑연 < SiOx(0<x<2)로 표시되는 산화실리콘 순으로 큰 것인 음극 조성물의 제조 방법.

11. In claim 10, the negative electrode conductive material comprises a single-walled carbon nanotube (SWCNT), Among the above cathode compositions, SiOx(0 <x<2)로 표시되는 산화실리콘, 흑연 및 단일벽 탄소 나노 튜브의 함량의 합계 100 중량부 기준 상기 SiOx(0<x<2)로 표시되는 산화실리콘은 0.5 중량부 내지 50 중량부; 상기 흑연은 45 중량부 내지 99 중량부; 및 상기 단일벽 탄소 나노 튜브(SWCNT)는 0.01 중량부 내지 5 중량부를 포함하며, A method for producing a negative electrode composition, wherein the natural graphite is included in an amount of 10 to 70 parts by weight based on 100 parts by weight of the graphite; and the artificial graphite is included in an amount of 30 to 90 parts by weight.

12. In claim 10, the SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 천연흑연의 BET 비표면적보다 1m 2 / g to 9m 2 / g A method for producing a large negative electrode composition.

13. In claim 10, the SiOx(0 <x<2)로 표시되는 산화실리콘의 BET 비표면적은 상기 인조흑연의 BET 비표면적보다 2m 2 / g to 10m 2 / g A method for producing a large negative electrode composition.

14. In claim 10, the BET specific surface area of ​​the natural graphite is 0.1 m greater than the BET specific surface area of ​​the artificial graphite. 2 / g to 2m 2 / g A method for producing a large negative electrode composition.

15. The entire house; and A negative electrode for a lithium secondary battery comprising a negative electrode active material layer comprising a negative electrode composition according to any one of claims 1 to 9 formed on one or both sides of the above-described collector.

16. Bipolar; A negative electrode for a lithium secondary battery according to claim 15; and A lithium secondary battery comprising a separator provided between the positive electrode and the negative electrode.

17. A lithium secondary battery according to claim 16, wherein the lithium secondary battery is a cylindrical battery.

18. A battery module comprising a lithium secondary battery according to claim 16.

19. A battery pack comprising a battery module according to claim 18.

20. A battery pack comprising a lithium secondary battery according to claim 16.