Negative electrode current collector for non-aqueous battery and non-aqueous battery including the same

Abstract

The present invention relates to a current collector for a non-aqueous negative electrode battery, wherein the current collector for a negative electrode comprises: a metal current collecting base material; and a conductive layer located on the metal current collecting base material, the conductive layer containing an ion-conductive polymer, the ion-conductive polymer containing a unit derived from a vinylidene fluoride-derived unit and a unit derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene, and there being a main peak in a region where 2-theta is from 20.5° to 20.9° during X-ray diffraction analysis of the conductive layer.

Description

Technical Field

[0001] [Cross - reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2022 - 0073087, filed on June 15, 2022, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

[0002] The present invention relates to a negative electrode current collector for a non - negative electrode battery and a non - negative electrode battery including the same.

Background Art

[0003] In recent years, with the development of personal IT devices and networks due to the development of the information society, the dependence of society as a whole on electrical energy has increased, and the development of battery technology for efficiently storing and utilizing electrical energy has been required.

[0004] In particular, as the interest in solving environmental problems and realizing a sustainable recycling society has increased, research on energy storage devices such as lithium - ion batteries and electric double - layer capacitors has been widely conducted. Among these, lithium secondary batteries have attracted attention as a battery system with the highest theoretical energy density among battery technologies.

[0005] Generally, a lithium secondary battery has a structure in which an electrode assembly composed of a positive electrode, a negative electrode, and a separator is impregnated with an electrolyte. Also, generally, the positive electrode is manufactured by coating a positive electrode mixture containing a positive electrode active material on an aluminum foil, and the negative electrode is manufactured by coating a negative electrode mixture containing a negative electrode active material on a copper foil. At this time, generally, a lithium transition metal oxide is used as the positive electrode active material, and a carbon - based active material, a silicon - based active material, etc. are used as the negative electrode active material.

[0006] In recent years, lithium metal batteries using lithium metal itself as the negative electrode active material have been commercialized. Furthermore, during the manufacture of the electrode, only the negative electrode current collector is used as the negative electrode. However, a negative electrode-free battery (Negative electrode-free battery or Anode free battery) that receives lithium from the positive electrode during charging and uses lithium metal as the negative electrode active material is being studied. Since the negative electrode mixture layer is not included in the negative electrode-free battery, more positive electrode mixture layers can be included, which is preferable from the viewpoint of high energy density.

[0007] However, during charging of the negative electrode-free battery, after lithium transmitted from the positive electrode is electrodeposited on the negative electrode current collector, there is a risk of forming lithium dendritic crystals. In the negative electrode-free battery, a decrease in charge and discharge efficiency may become a problem due to an increase in irreversible capacity caused by the growth of such lithium dendritic crystals. In addition, since the lithium metal layer formed on the negative electrode current collector during charging of the negative electrode-free battery has a low electrodeposition density, there is a risk of causing side reactions of the electrolyte, so a rapid decrease in life performance may occur.

[0008] Korean Patent Publication No. 10-2019-0083878 discloses a negative electrode-free lithium metal battery, but it was unable to present an alternative to the above-described problems.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] One problem of the present invention is to provide a negative electrode current collector for a negative electrode-free battery that suppresses the formation of lithium dendritic crystals during charge and discharge of a negative electrode-free battery including the same, improves electrolyte impregnation properties and ionic conductivity, and improves charge and discharge efficiency and life performance.

[0011] Another object of the present invention is to provide a non-aqueous negative electrode battery including the negative electrode current collector for the non-aqueous negative electrode battery described above.

Means for Solving the Problems

[0012] The present invention provides a negative electrode current collector for a non-aqueous negative electrode battery, the negative electrode current collector including: a metal current collecting base material; and a conductive layer located on the metal current collecting base material, the conductive layer including an ion-conductive polymer, the ion-conductive polymer including a unit derived from a vinylidene fluoride-derived unit and a unit derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene, and a main peak existing in a region where 2-theta is from 20.5° to 20.9° during X-ray diffraction analysis of the conductive layer.

[0013] The present invention also provides a non-aqueous negative electrode battery including: the negative electrode current collector for the non-aqueous negative electrode battery described above; a positive electrode facing the negative electrode current collector for the non-aqueous negative electrode battery; a separator interposed between the negative electrode current collector for the non-aqueous negative electrode battery and the positive electrode; and an electrolyte, wherein the conductive layer is arranged to face the separator.

Effects of the Invention

[0014] The negative current collector for a non-aqueous battery according to the present invention includes a conductive layer containing an ion-conductive polymer including a unit derived from vinylidene fluoride and a unit derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene, and a main peak exists in a region where 2θ is from 20.5° to 20.9° during X-ray diffraction analysis of the conductive layer. Crystallization can be adjusted to a preferable level through a 2θ range during X-ray diffraction analysis of the conductive layer, and piezoelectric property can be improved, whereby formation of lithium dendritic crystals can be effectively suppressed by the piezoelectric property of the conductive layer during lithium plating. On the other hand, the ion-conductive polymer contained in the conductive layer simultaneously includes a unit derived from vinylidene fluoride in the polymer and a unit derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene. In particular, the unit derived from hexafluoropropylene and / or chlorotrifluoroethylene improves the electrolyte impregnation property of the conductive layer to improve lithium ion conductivity, and improves the flexibility of the conductive layer to effectively accommodate volume changes during lithium electroplating and desorption.

[0015] Therefore, a non-aqueous battery including the negative current collector for a non-aqueous battery described above can have a high overall energy density because no separate negative electrode active material layer is formed, suppress formation of lithium dendritic crystals, which is a problem in non-aqueous batteries, to ensure safety, improve lithium ion conductivity, enable effective electroplating and desorption of lithium from the positive electrode to the negative electrode, and consequently exhibit excellent charge / discharge efficiency and life performance.

Brief Description of Drawings

[0016]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0017] The terms and words used in this specification and the claims should not be construed as being limited to their ordinary or dictionary meanings. In accordance with the principle that the inventor can appropriately define the concept of the terms in order to explain his invention in the best way, they should be construed as meanings and concepts consistent with the technical idea of the present invention.

[0018] Also, in this specification, terms such as "comprising", "including" or "having" are intended to specify the presence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood not to preclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0019] The average particle size (D 50 ) in this specification can be defined as the particle size corresponding to 50% of the volume cumulative amount in the particle size distribution curve of the particles. The average particle size (D 50 ) can be measured, for example, using the laser diffraction method. The laser diffraction method can generally measure particle sizes in the range from the submicron region to about several millimeters, and can obtain highly reproducible and highly resolved results.

[0020] Negative electrode current collector for non-aqueous negative electrode battery The present invention provides a negative electrode current collector for a non-aqueous negative electrode battery. Specifically, the negative electrode current collector for a non-aqueous negative electrode battery may be a negative electrode current collector for a non-aqueous lithium secondary battery.

[0021] Specifically, for the negative electrode current collector for the non-aqueous negative electrode battery, the negative electrode current collector includes a metal current collecting base material; and a conductive layer located on the metal current collecting base material, the conductive layer includes an ion conductive polymer, and includes a unit derived from a vinylidene fluoride-derived unit and at least one unit selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene, and there is a main peak in the region where 2θ is from 20.5° to 20.9° during X-ray diffraction analysis of the conductive layer.

[0022] The metal current collecting base material is not particularly limited as long as it has high conductivity without inducing a chemical change in the battery. Specifically, the metal current collecting base material can include at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, and an aluminum-cadmium alloy, and can specifically include copper.

[0023] The thickness of the metal current collecting base material may be from 3 μm to 500 μm, and specifically, may be from 3 μm to 20 μm in terms of considering all of high energy density and mechanical strength.

[0024] The metal current collecting base material may be used in various forms such as a film, a sheet, a foil, a net, a mesh, a porous body, a foam, and a non-woven fabric body.

[0025] The metal current collecting base material may have an uneven structure formed on its surface. Such an uneven structure can enable smoother lithium plating during charge and discharge of the non-aqueous negative electrode battery including the negative electrode current collector for the non-aqueous negative electrode battery.

[0026] The conductive layer is located on the metal current collecting base material. The conductive layer can be located on at least one surface of the metal current collecting base material, specifically, on one or both surfaces of the metal current collecting base material.

[0027] The conductive layer contains the ion-conductive polymer. The ion-conductive polymer contains units derived from vinylidene fluoride (VdF) and units derived from at least one monomer selected from the group consisting of hexafluoropropylene (HFP) and chlorotrifluoroethylene (CTFE).

[0028] Generally, in the case of a polymer containing only units derived from vinylidene fluoride (specifically, PVdF), it has piezoelectric properties and has an ion conductivity above a certain level, but shows poor performance in terms of electrolyte impregnation and inferior performance in flexibility, which is a problem. In particular, in the negative electrode for a non-aqueous electrolyte battery, when the electrolyte cannot be sufficiently impregnated, the mobility of lithium ions cannot be sufficiently ensured, so the formation of lithium dendrites is promoted, and there is a risk of significantly reducing the life performance. Also, when the flexibility of the conductive layer decreases, the volume change when lithium is electrodeposited from the positive electrode cannot be easily accommodated, so there is a problem that smooth charge and discharge efficiency cannot be exhibited.

[0029] In order to solve such problems, the conductive layer according to the present invention contains an ion-conductive polymer containing units derived from vinylidene fluoride and units derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene. When units derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene are contained in the ion-conductive polymer, while not inhibiting the ion conductivity due to the piezoelectric properties of the units derived from vinylidene fluoride, it increases the electrolyte impregnation property to improve the mobility of lithium ions, significantly prevents the formation of lithium dendrites, easily accommodates the volume change due to the electrodeposition of lithium, and enables the realization of a negative electrode for a non-aqueous electrolyte battery having high charge and discharge performance and life performance.

[0030] Specifically, the ion-conductive polymer may be a vinylidene fluoride-hexafluoropropylene copolymer, a vinylidene fluoride-chlorotrifluoroethylene copolymer, or a vinylidene fluoride-hexafluoropropylene-chlorotrifluoroethylene copolymer.

[0031] Further, the ion-conductive polymer may contain units derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene in an amount of 1% to 30% by weight, specifically 3% to 25% by weight, more specifically 5% to 20% by weight, and even more specifically 12% to 18% by weight. When within the above range, it is preferable in terms of being able to exhibit high electrolyte impregnation properties while not inhibiting the piezoelectric properties and the resulting ion conductivity due to the units derived from vinylidene fluoride.

[0032] Also, a main peak exists in the region where 2 theta (2θ) is from 20.5° to 20.9° during the X-ray diffraction analysis of the conductive layer. Generally, PVdF is known as a substance that includes a crystal structure and has piezoelectric properties. At this time, the piezoelectric property is defined as an interaction in which mechanical vibration energy and electrical energy can be mutually converted. Thus, a substance having piezoelectric properties can generate a voltage when pressure is applied and can undergo mechanical deformation when an electric field is applied. Such piezoelectric properties of PVdF are attributed to the polarities of the CH2 groups and CF2 groups that cross-link and polymerize within PVdF. On the other hand, PVdF has an alpha phase, a beta phase, a gamma phase, a delta phase, etc. depending on its three-dimensional structure. The C-F bond in PVdF has a strong polarity due to the high electronegativity of F. The alpha phase has no or little piezoelectric properties because the VdF monomers in PVdF are aligned in opposite directions to cancel the dipole moment, while the beta phase is understood to have relatively excellent piezoelectric properties because the VdF monomers in PVdF are aligned in the same direction to maximize the dipole moment.

[0033] At this time, the fact that the main peak exists in the region where 2 theta (2θ) is from 20.5° to 20.9° during the X-ray diffraction analysis of the conductive layer may mean that in the vinylidene fluoride-derived unit contained in the ion-conductive polymer or the polymer containing the same, the beta phase of the vinylidene fluoride-derived unit exists as a dominant phase compared to other phases. In the case of the conductive layer according to the present invention in which the vinylidene fluoride-derived unit containing the beta phase as a main component is included and is embodied to have a low crystallinity, it can be understood to have a relatively strong dipole moment and excellent piezoelectric characteristics compared to the conductive layer containing the vinylidene fluoride-derived unit containing the alpha phase as a main component. On the other hand, when the alpha phase of the PVdF exists as a dominant phase compared to other phases, the main peak will exist in the region where 2 theta (2θ) is approximately 20.0° during the X-ray diffraction analysis. When the PVdF contained in the conductive layer contains the alpha phase as a main component, not only does the crystallinity increase, resulting in a decrease in electrolyte impregnation and ionic conductivity, but also the piezoelectric characteristics decrease, and the precipitation of lithium dendritic crystals cannot be sufficiently prevented.

[0034] Therefore, the conductive layer included in the negative electrode current collector for the non-aqueous negative electrode battery according to the present invention includes an ion-conductive polymer containing units derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene together with vinylidene fluoride-derived units. Since there is a main peak in the region where 2 theta (2θ) is from 20.5° to 20.9° during X-ray diffraction analysis, it improves the mobility of lithium ions, significantly prevents the formation of lithium dendrites, and enables the realization of a negative electrode for a non-aqueous negative electrode battery having high life performance. On the other hand, during X-ray diffraction analysis of the conductive layer, the 2θ range is adjusted to the arrangement structure of vinylidene fluoride units. However, a conductive layer containing only PVdF containing only vinylidene fluoride units has very low flexibility apart from exhibiting piezoelectric properties, so it cannot accommodate the volume change due to lithium electrodeposition, and as a result, there is a risk of promoting the formation of lithium dendrites. In this regard, the conductive layer according to the present invention can also achieve the effect of improving the flexibility of the conductive layer by including units derived from hexafluoropropylene and / or chlorotrifluoroethylene in the ion-conductive polymer while adjusting the range of 2 theta (2θ) during X-ray diffraction analysis to a specific range.

[0035] On the other hand, the 2θ value at which the main peak appears during X-ray diffraction analysis of the conductive layer is derived from the arrangement structure of vinylidene fluoride-derived units. However, even if hexafluoropropylene, chlorotrifluoroethylene, etc. are copolymerized with vinylidene fluoride, the backbone structure of vinylidene fluoride and the arrangement structure of vinylidene fluoride-derived units in the copolymer are maintained, so the 2θ value at which the main peak appears during X-ray diffraction analysis of the conductive layer described above does not change.

[0036] In this specification, the "main peak" means the peak where the intensity is the highest when a graph regarding 2 theta (2-theta) and intensity is created by X-ray diffraction analysis.

[0037] The conductive layer can further contain a lithium salt together with the ion-conductive polymer. The lithium salt can contribute to the formation of a solid electrolyte interface film (Solid Electrolyte Interface layer, SEI layer) on the surface of the negative electrode current collector during initial charging, thereby further improving the ionic conductivity of the conductive layer and contributing to the improvement of the life performance.

[0038] The lithium salt can include at least one selected from the group consisting of LiCl, LiBr, LiI, LiNO3, LiClO4, LiBF4, LiB 10 Cl 10 , LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiAlCl4, CH3SO3Li, CF3SO3Li, LiSCN, LiC(CF3SO2)3, (CF3SO2)2NLi, (FSO2)2NLi, lithium chloroborane, lithium lower aliphatic carboxylic acid, lithium 4-phenylborate, and lithium imide. Specifically, it can promote the formation of a stable SEI layer (SEI layer) with an increased content of inorganic substances such as Li3N and Li2O on the surface of the negative electrode current collector, and can suppress the formation of lithium dendrites by inducing the surface shape of the plated lithium metal to be spherical during charging. In this regard, it can contain LiNO3.

[0039] When the conductive layer contains a lithium salt, the lithium salt may be contained in the conductive layer at 0.1% by weight to 20% by weight, more specifically 2% by weight to 10% by weight. When within this range, it realizes the effect of forming a stable SEI layer and preventing the formation of lithium dendrites, effectively compensates for the concentration gradient caused by the consumption of lithium ions on the surface of the negative electrode current collector during charge and discharge, and is preferable in terms of preventing an increase in resistance when an excessive amount of lithium salt is added.

[0040] The conductive layer can further include at least one additional polymer selected from the group consisting of an acrylic polymer, polyurethane, polyurea, styrene-butadiene rubber, polyimide, and polystyrene, together with the ion conductive polymer. The additional polymer may be included in the conductive layer in terms of increasing the degree of swelling of the conductive layer and improving the electrolyte impregnation property. On the other hand, even if the additional polymer is included in the conductive layer, microseparation occurs during drying for the production of the conductive layer, and the influence on the formation of crystals of the polymer containing vinylidene fluoride units is not significant. Therefore, the 2θ value at which the main peak appears during the X-ray diffraction analysis of the conductive layer described above does not change depending on the presence or absence of the additional polymer.

[0041] The acrylic polymer may be a polymer polymerized from at least one monomer selected from butyl acrylate, acrylic acid, and acrylonitrile.

[0042] When the conductive layer further includes the additional polymer, the weight ratio of the ion conductive polymer and the additional polymer contained in the conductive layer may be from 10:90 to 99.9:0.1, specifically from 50:50 to 99.5:0.5. When in the above range, it is preferable in terms of maintaining the shape of the conductive layer and increasing the electrolyte impregnation property.

[0043] The thickness of the conductive layer may be from 1 μm to 50 μm, specifically from 2 μm to 10 μm, more specifically from 2 μm to 3 μm. When in the above range, while embodying the effects of suppressing the formation of lithium dendritic crystals and improving the electrolyte impregnation characteristics by applying the conductive layer, the volume of the negative electrode current collector including the conductive layer can be reduced, so that the energy density of the secondary battery can be improved.

[0044] The conductive layer can be manufactured by applying a composition for forming a conductive layer containing an ion-conductive polymer to the metal current collector substrate and drying it. At this time, it is important to appropriately adjust the drying temperature so that the beta phase in PVdF becomes the dominant phase. If the drying temperature is too high, crystallization proceeds excessively and the content of alpha-phase PVdF increases, making it difficult to embody the conductive layer intended by the present invention.

[0045] Specifically, the method for manufacturing the conductive layer can include the following steps. (a) Applying a composition for forming a conductive layer containing the ion-conductive polymer to the metal current collector substrate; and (b) Drying the applied composition for forming a conductive layer.

[0046] The composition for forming a conductive layer can further contain a solvent together with the ion-conductive polymer. The solvent may be, for example, N-methylpyrrolidone (NMP).

[0047] The drying temperature during drying may be appropriately adjusted according to the type of polymer. For example, the drying temperature may be 95°C or lower, more specifically 30°C to 75°C, and even more specifically 40°C to 65°C. At this time, the drying time may be 1 hour to 5 hours.

[0048] The drying may be performed, for example, under vacuum conditions.

[0049] After the drying, the temperature may be lowered to room temperature (specifically 20°C to 25°C), and additional drying may be further performed. The additional drying may be performed, for example, for 1 hour to 100 hours, specifically 24 hours to 80 hours.

[0050] Non-aqueous negative electrode battery In addition, the present invention provides a non-aqueous negative electrode battery including the negative electrode current collector for a non-aqueous negative electrode battery described above. The non-aqueous negative electrode battery may be a non-aqueous lithium secondary battery.

[0051] Specifically, the non-aqueous negative electrode battery includes the negative electrode current collector for the non-aqueous negative electrode battery described above; a positive electrode facing the negative electrode current collector for the non-aqueous negative electrode battery; a separator interposed between the negative electrode current collector for the non-aqueous negative electrode battery and the positive electrode; and an electrolyte. At this time, the conductive layer may be arranged to face the separator.

[0052] The features of the negative electrode current collector for the non-aqueous negative electrode battery are as described above.

[0053] The negative electrode current collector for the non-aqueous negative electrode battery can itself be used as the negative electrode for the non-aqueous negative electrode battery.

[0054] The negative electrode for the non-aqueous negative electrode battery or the negative electrode current collector for the non-aqueous negative electrode battery can be assembled into an electrode assembly and a non-aqueous negative electrode battery together with a positive electrode, a separator, etc. without containing a separate lithium insertion substance or lithium metal. As will be described later, in the non-aqueous negative electrode battery including the negative electrode for the non-aqueous negative electrode battery or the negative electrode current collector for the non-aqueous negative electrode battery, lithium ions from the positive electrode can move to the negative electrode for the non-aqueous negative electrode battery or the negative electrode current collector for the non-aqueous negative electrode battery during charging to form a lithium metal layer. Charging and discharging of the non-aqueous negative electrode battery can be performed by the formation or removal of such a lithium metal layer.

[0055] The positive electrode is arranged to face the negative electrode current collector for the non-aqueous negative electrode battery.

[0056] The positive electrode can include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector.

[0057] The positive electrode current collector is not particularly limited as long as it has conductivity without inducing a chemical change in the battery. For example, stainless steel, aluminum, nickel, titanium, fired carbon, or a material obtained by surface treatment of the surface of aluminum or stainless steel with carbon, nickel, titanium, silver, etc. may be used.

[0058] The positive electrode current collector generally can have a thickness of 3 μm to 500 μm.

[0059] The positive electrode active material layer is formed on the positive electrode current collector and contains a positive electrode active material.

[0060] The positive electrode active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium composite metal oxide containing one or more metals such as cobalt, manganese, nickel, or aluminum and lithium. More specifically, the lithium composite metal oxide may be a lithium-manganese-based oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt-based oxide (e.g., LiCoO2, etc.), a lithium-nickel-based oxide (e.g., LiNiO2, etc.), a lithium-nickel-manganese-based oxide (e.g., LiNi 1-Y Mn Y O2 (where 0 < Y < 1), LiMn 2-z Ni z O4 (where 0 < Z < 2), etc.), a lithium-nickel-cobalt-based oxide (e.g., LiNi 1-Y1 Co Y1 O2 (where 0 < Y1 < 1), etc.), a lithium-manganese-cobalt-based oxide (e.g., LiCo 1-Y2 Mn Y2 O2 (where 0 < Y2 < 1), LiMn 2-z1 Co z1 O4 (where 0 < Z1 < 2), etc.), a lithium-nickel-manganese-cobalt-based oxide (e.g., Li(Ni p Co q Mn r1 )O2 (where 0 < p < 1, 0 < q < 1, 0 < r1 < 1, p + q + r1 = 1) or Li(Ni p1 Co q1 Mn r2 )O4 (where 0 < p1 < 2, 0 < q1 < 2, 0 < r2 < 2, p1 + q1 + r2 = 2), etc.), or a lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M S2)O2 (where M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are atomic fractions of independent elements, where 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc.), and one or more of these compounds may be included. Among these, in terms of being able to enhance the capacity characteristics and stability of the battery, the lithium composite metal oxide is LiCoO2, LiMnO2, LiNiO2, lithium nickel manganese cobalt oxide (for example, Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, or Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.), or lithium nickel cobalt aluminum oxide (for example, Li(Ni 0.8 Co 0.15 Al 0.05 )O2, etc.).

[0061] The positive electrode active material may be contained at 80% to 99% by weight based on the total weight of the positive electrode active material layer.

[0062] In addition to the positive electrode active material described above, the positive electrode active material layer may further selectively contain at least one additive selected from the group consisting of a binder and a conductive material.

[0063] The binder is a component that assists in binding the active material and the conductive material, etc., and binding to the current collector, and is usually added in an amount of 1% by weight to 30% by weight based on the total weight of the positive electrode active material layer. Examples of such binders include polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, fluororubber, various copolymers, and the like.

[0064] The conductive material is not particularly limited as long as it has conductivity without inducing a chemical change in the battery. For example, graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers and metal fibers; metal powders such as carbon fluoride, aluminum, nickel powder; conductive whiskers such as zinc oxide, potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used. Specific examples of commercially available conductive materials include acetylene black-based (products manufactured by Chevron Chemical Company, Denka Singapore Private Limited, Gulf Oil Company, etc.), Ketjenblack, EC-based (products manufactured by Armak Company), Vulcan XC-72 (products manufactured by Cabot Company), and Super P (products manufactured by Timcal).

[0065] The conductive material may be contained in an amount of 1% by weight to 30% by weight based on the total weight of the positive electrode active material layer.

[0066] The positive electrode active material layer may be manufactured by adding a positive electrode active material and an additive selectively containing a binder and / or a conductive material to a solvent to produce a positive electrode slurry, and then coating, rolling, and drying the slurry on the positive electrode current collector.

[0067] The solvent may include an organic solvent such as NMP (N-methyl-2-pyrrolidone), and when the positive electrode active material and selectively a binder and a conductive material are included, it may be used in an amount that provides a preferable viscosity. For example, the concentration of the solid content including the positive electrode active material and selectively a binder and a conductive material may be included so as to be 50% by weight to 95% by weight, preferably 70% by weight to 90% by weight.

[0068] The separator separates the negative electrode and the positive electrode to provide a migration path for lithium ions, and generally, any separator that can be used in a lithium secondary battery can be used without particular limitation. In particular, a separator having low resistance to the ion migration of the electrolyte and excellent electrolyte moisture retention ability is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin-based polymer such as a polyethylene homopolymer, a polypropylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminate structure of two or more layers thereof may be used. Also, a normal porous nonwoven fabric, for example, a nonwoven fabric made of high melting point glass fibers, polyethylene terephthalate fibers, etc. may be used. Further, a coated separator containing a ceramic component or a polymer substance may be used to ensure heat resistance or mechanical strength, and it may be selectively used in a single-layer or multilayer structure.

[0069] In addition, examples of the electrolyte used in the present invention include, but are not limited to, an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, and a molten inorganic electrolyte that can be used in the manufacture of a lithium secondary battery. Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0070] As the organic solvent, any medium that can serve as a medium through which ions involved in the electrochemical reaction of the battery can move may be used without particular limitation. Specifically, examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate, gamma-butyrolactone, and epsilon-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; carbonate solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may contain a double bond aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes. Among these, carbonate solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having a high ionic conductivity and a high dielectric constant that can enhance the charge and discharge performance of the battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred. In this case, when the cyclic carbonate and the chain carbonate are mixed and used at a volume ratio of about 1:1 to about 1:9, the performance of the electrolyte can be excellent.

[0071] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. The concentration of the lithium salt is preferably used within the range of 0.1 M to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and lithium ions can move effectively.

[0072] On the other hand, the non-aqueous negative electrode battery may further include a lithium metal layer formed on the negative electrode current collector for the non-aqueous negative electrode battery, and the lithium metal layer may be formed by the movement of lithium ions from the positive electrode upon charging of the non-aqueous negative electrode battery. Specifically, the lithium metal layer may be formed or disposed between the metal current collector substrate and the conductive layer.

[0073] As described above, the non-aqueous negative electrode battery according to the present invention is useful in the fields of portable devices such as mobile phones, notebook computers, digital cameras, etc., and electric vehicles such as hybrid electric vehicles (HEV), etc., and can be preferably used as a constituent battery of a medium- to large-sized battery module in particular. Therefore, the present invention also provides a medium- to large-sized battery module including the non-aqueous negative electrode battery as described above as a unit battery.

[0074] Such a medium- to large-sized battery module can be preferably applied to power sources that require high output and large capacity, such as electric vehicles, hybrid electric vehicles, and power storage devices.

[0075] Hereinafter, embodiments of the present invention will be described in detail so that those having ordinary knowledge in the technical field to which the present invention pertains can easily implement it. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein.

[0076] Examples and Comparative Examples Example 1: Production of a Negative Current Collector for a Non-aqueous Anode Battery A copper foil was prepared as a metal current collector substrate (thickness: 15 μm).

[0077] A composition for forming a conductive layer (solid content: 10% by weight) in which a vinylidene fluoride - hexafluoropropylene copolymer (VdF - HFP Copolymer) containing 15% by weight of units derived from hexafluoropropylene (HFP) as an ion - conductive polymer was dispersed in an N - methylpyrrolidone (NMP) solvent was prepared. The composition for forming the conductive layer was applied to the metal current collector substrate, dried at 60 °C for 2 hours under vacuum conditions (about - 0.1 MPa), and then gradually cooled to room temperature and further dried for 70 hours to form a conductive layer (thickness: 2.5 μm). The metal current collector substrate with the formed conductive layer was used as a negative current collector for a non - aqueous anode battery.

[0078] Example 2: Production of a Negative Current Collector for a Non-aqueous Anode Battery A negative current collector for a non - aqueous anode battery was produced in the same manner as in Example 1, except that LiNO3 was further included in the composition for forming the conductive layer at 5% by weight based on the solid content weight of the composition for forming the conductive layer.

[0079] The thickness of the conductive layer included in the negative current collector for the non - aqueous anode battery of Example 2 was 2.5 μm.

[0080] Example 3: Production of a Negative Current Collector for a Non-aqueous Anode Battery A negative current collector for a non - aqueous anode battery was produced in the same manner as in Example 1, except that a VdF - HFP copolymer containing 5% by weight of units derived from HFP was used instead of the VdF - HFP copolymer containing 15% by weight of units derived from HFP.

[0081] The thickness of the conductive layer included in the negative electrode current collector for the non-aqueous negative electrode battery of Example 3 was 2.5 μm.

[0082] Example 4: Production of a negative electrode current collector for a non-aqueous negative electrode battery A negative electrode current collector for a non-aqueous negative electrode battery was produced in the same manner as in Example 1, except that a VdF-HFP copolymer containing 20% by weight of HFP-derived units was used instead of the VdF-HFP copolymer containing 15% by weight of HFP-derived units.

[0083] The thickness of the conductive layer included in the negative electrode current collector for the non-aqueous negative electrode battery of Example 4 was 2.5 μm.

[0084] Example 5: Production of a negative electrode current collector for a non-aqueous negative electrode battery A negative electrode current collector for a non-aqueous negative electrode battery was produced in the same manner as in Example 1, except that a VdF-CTFE copolymer containing 20% by weight of chlorotrifluoroethylene (CTFE)-derived units was used instead of the VdF-HFP copolymer containing 15% by weight of HFP-derived units.

[0085] The thickness of the conductive layer included in the negative electrode current collector for the non-aqueous negative electrode battery of Example 5 was 2.5 μm.

[0086] Comparative Example 1: Production of a negative electrode current collector for a non-aqueous negative electrode battery A negative electrode current collector for a non-aqueous negative electrode battery was produced in the same manner as in Example 1, except that during drying of the composition for forming the conductive layer, it was dried at 100 °C for 10 hours under vacuum conditions (about -0.1 MPa) and no additional drying was performed.

[0087] The thickness of the conductive layer included in the negative electrode current collector for the non-aqueous negative electrode battery of Comparative Example 1 was 2.5 μm.

[0088] Comparative Example 2: Production of a negative electrode current collector for a non-aqueous negative electrode battery A negative electrode current collector for a non-aqueous negative electrode battery was produced in the same manner as in Example 1, except that polyvinylidene fluoride (PVdF) was used instead of the VdF-HFP copolymer containing 15% by weight of HFP-derived units.

[0089] The thickness of the conductive layer contained in the negative electrode current collector for the non-aqueous negative electrode battery of Comparative Example 2 was 2.5 μm.

[0090] Experimental Example 1: X-ray Diffraction Analysis In the negative electrode current collectors for non-aqueous negative electrode batteries manufactured in Example 1 and Comparative Example 1, X-ray diffraction analysis of the conductive layer was performed. Figures 1 and 2 show the results of X-ray diffraction analysis of the conductive layers of Example 1 and Comparative Example 1, respectively.

[0091] The conditions for XRD analysis are as follows. 1) Type and wavelength of the light source: X-ray wavelength generated by Cu Kα was used, and the wavelength (λ) of the light source was 0.15406 nm. 2) Method for preparing the sample: After cutting the conductive layer to the size of the cover glass, the sample was prepared by adhering it to the cover glass using double-sided tape. After attaching the prepared sample to the groove of the holder, a flattening operation was performed with a slide glass so that the height of the sample became constant. 3) Set conditions of the XRD analysis equipment: Fixed Divergence Slit (FDS) was set to 0.5, and an energy-dispersive 1D detector was used for the detector. The measurement mode was set to the Linear mode, the measurement region was set to the region where 2θ was from 10° to 30°, and the measurement conditions were set to scan 2θ by 0.016° every 4 seconds.

[0092] As shown in Figure 1, a main peak is observed at approximately 20.7° in the conductive layer of Example 1. Thereby, it can be confirmed that the PVdF contained in the conductive layer of Example 1 has a dominant β-phase.

[0093] On the other hand, a main peak is observed at approximately 20.0° in the conductive layer of Comparative Example 1. Thereby, it can be confirmed that the PVdF contained in the conductive layer of Example 1 has a dominant α-phase.

[0094] On the one hand, comparing FIGS. 1 and 2 with each other, it can be seen that the main peak intensity (Intensity) in the X-ray diffraction analysis results of Comparative Example 1 is higher than that in the case of Example 1. This means that the crystallinity of the conductive layer in Comparative Example 1 is higher than the crystallinity of the conductive layer in Example 1.

[0095] Taking this point into comprehensive consideration, it can be seen that the conductive layer of Example 1 and the negative electrode current collector for a non-aqueous negative electrode battery including the same have relatively low crystallinity and contain PVdF in which the beta phase is the dominant phase.

[0096] Experimental Example 2: Evaluation of Charge and Discharge Efficiency <Manufacture of Non-aqueous Negative Electrode Battery> As the positive electrode active material, LiCoO2; as the conductive material, carbon black; and as the binder, PVDF; were mixed in a weight ratio of 96:2:2 in an N-methylpyrrolidone solvent to produce a positive electrode slurry. After applying this to an aluminum current collector (thickness: 20 μm), it was dried and rolled to form a positive electrode active material layer (thickness: 130 μm), which was used as the positive electrode.

[0097] An electrode assembly including the negative electrode current collector for a non-aqueous negative electrode battery according to Example 1, a positive electrode facing the negative electrode current collector, and a polyethylene separator interposed between the positive electrode and the negative electrode was manufactured, and after housing this in a battery case, the electrolyte was injected and sealed to manufacture a non-aqueous negative electrode battery.

[0098] As the electrolyte used at this time, ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed as organic solvents in a volume ratio of 2:8, vinylene carbonate (VC) was added as an additive at 0.5% by weight based on the total weight of the electrolyte, and LiPF6 was added as a lithium salt at a concentration of 1.2 mol / L.

[0099] Except for using the negative electrode current collectors for non-aqueous negative electrode batteries of Examples 2 to 5 and Comparative Examples 1 and 2, the non-aqueous negative electrode batteries of Examples 2 to 5 and Comparative Examples 1 and 2 were manufactured in the same manner as Example 1.

[0100] <Evaluation of Capacity Retention Rate> The non-aqueous negative electrode batteries of the examples and comparative examples manufactured as described above were subjected to cycle charging and discharging at 25°C under the following conditions, and the capacity retention rate was evaluated. The graph of the capacity retention rate by cycle is shown in FIG. 3, and the capacity retention rate at 5 cycles is shown in Table 1 below.

[0101] The capacity retention rate was evaluated by the following formula. Capacity Retention Rate (%) = {(Discharge Capacity of Non-aqueous Negative Electrode Battery at N Cycles) / (Discharge Capacity of Non-aqueous Negative Electrode Battery at the First Cycle)} × 100 (In the above formula, N is an integer of 1 or more)

[0102] ※ Charging and Discharging Conditions Charging: CC / CV mode; 0.1C; 4.45V, 1 / 20C cut-off Discharging: CC mode; 0.1C; 3.0V cut-off

[0103]

Table 1

[0104] As shown in Table 1 and FIG. 3, it can be seen that the non-aqueous negative electrode battery according to the example exhibits an excellent level of charge and discharge efficiency compared to the non-aqueous negative electrode battery according to the comparative example.

Claims

1. A negative electrode current collector for a non-aqueous negative electrode battery, said negative electrode current collector comprising: a metal current collecting substrate; and a conductive layer located on said metal current collecting substrate; said conductive layer containing an ion-conductive polymer, said ion-conductive polymer containing units derived from vinylidene fluoride units and units derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene, and a main peak existing in a region where 2θ is from 20.5° to 20.9° during X-ray diffraction analysis of said conductive layer, the negative electrode current collector for a non-aqueous negative electrode battery.

2. The units derived from at least one monomer selected from the group consisting of hexafluoropropylene and chlorotrifluoroethylene are contained in said ion-conductive polymer in an amount of 1% by weight to 30% by weight, the negative electrode current collector for a non-aqueous negative electrode battery according to Claim 1.

3. Said conductive layer further containing a lithium salt, the negative electrode current collector for a non-aqueous negative electrode battery according to Claim 1.

4. Said lithium salt is LiCl, LiBr, LiI, LiNO ３ , LiClO ４ , LiBF ４ , LiB １０ Cl １０ , LiPF ６ , LiCF ３ SO ３ , LiCF ３ CO ２ , LiAsF ６ , LiSbF ６ , LiAlCl ４ , CH ３ SO ３ Li, CF ３ SO ３ Li, LiSCN, LiC(CF ３ SO ２ ) ３ , (CF ３ SO ２ ) ２NLi, (FSO ２ ) ２ The negative electrode current collector for a non-aqueous negative electrode battery according to claim 3, comprising at least one selected from the group consisting of NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium 4-phenylborate, and lithium imide.

5. The lithium salt contains LiNO ３ The negative electrode current collector for a non-aqueous negative electrode battery according to claim 3.

6. The lithium salt is contained in the conductive layer at 0.1% by weight to 20% by weight. The negative electrode current collector for a non-aqueous negative electrode battery according to claim 3.

7. The thickness of the conductive layer is 1 μm to 50 μm. The negative electrode current collector for a non-aqueous negative electrode battery according to claim 1.

8. The metal current collector substrate contains at least one selected from the group consisting of copper, stainless steel, aluminum, nickel, titanium, and an aluminum-cadmium alloy. The negative electrode current collector for a non-aqueous negative electrode battery according to claim 1.

9. The metal current collector substrate contains copper. The negative electrode current collector for a non-aqueous negative electrode battery according to claim 1.

10. The negative electrode current collector for a non-aqueous negative electrode battery according to any one of claims 1 to 9; A positive electrode facing the negative electrode current collector for a non-aqueous negative electrode battery; A separator interposed between the negative electrode current collector for a non-aqueous negative electrode battery and the positive electrode; and An electrolyte; comprising, The conductive layer is arranged to face the separator. A non-aqueous negative electrode battery.

11. The non-aqueous negative electrode battery further includes a lithium metal layer formed on the negative electrode current collector for a non-aqueous negative electrode battery, The lithium metal layer is formed by the movement of lithium ions from the positive electrode upon charging of the non-aqueous negative electrode battery. The non-aqueous negative electrode battery according to claim 10.

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