Electrode and secondary battery comprising same

Abstract

The present invention relates to an electrode comprising an electrode active material layer including an electrode active material, a conductive material, and a binder, wherein the electrode active material layer has a specific surface area of the electrode active material of 10 m2 / g to 50 m2 / g, and A, which is defined by factors of the input amounts of the electrode active material and the conductive material in the electrode, the loading amount and specific surface area of the electrode active material, and the specific surface area and average particle diameter of the conductive material, of 0.70 cm2㎛ / mg or more. Accordingly, it is possible to implement an electrode having a large loading amount and low resistance, thereby providing a secondary battery having excellent capacity characteristics and improved resistance characteristics.

Description

Electrode and secondary battery containing the same

[0001] This specification relates to an electrode and a secondary battery including the same, and more specifically, to an electrode having excellent appearance characteristics and a secondary battery including the same.

[0002]

[0003] Due to the rapid increase in fossil fuel use, the demand for alternative or clean energy is increasing, and as part of this, the most actively researched field is power generation and storage using electrochemical reactions.

[0004] Secondary batteries are a prime example of electrochemical devices that utilize this electrochemical energy, and their applications are expanding. With the recent technological development and increasing demand for portable devices such as laptops, mobile phones, and cameras, the demand for secondary batteries as an energy source has rapidly increased. Among these secondary batteries, lithium secondary batteries, which boast high energy density and high capacity, have been extensively studied and are now commercialized and widely used.

[0005] Furthermore, in the field of secondary battery technology, the development of batteries with high energy density and excellent rapid charging performance is continuously demanded to advance energy storage devices. In particular, with the growing demand for large-capacity energy storage devices such as electric vehicles, the importance of rapid charging technology capable of high power charging in a short time is increasing to maximize user convenience. Against this backdrop, the development of secondary batteries that maximize energy density while maintaining stability during high-speed charging is becoming a leading technology trend.

[0006] Meanwhile, secondary batteries require a drying process during the electrode manufacturing process, and cracks or wrinkles frequently form on the electrode surface during this process, resulting in defects. These problems are more pronounced when using active materials with a large surface area or when the electrode is loaded heavily. These electrode surface morphology defects can lead to lithium salt precipitation, shortening the battery's lifespan and increasing cell resistance.

[0007] Accordingly, to solve the above problems, research is being conducted to improve cell life and resistance while improving appearance characteristics in various ways.

[0008]

[0009] In one aspect of the present specification, an electrode is provided in which the problem of occurrence of cracks and wrinkles on the surface is improved by controlling the specific surface area, particle size, and loading amount of the electrode active material and conductive material included in the electrode active material layer.

[0010] In another aspect of the present specification, it is intended to provide a secondary battery having excellent resistance characteristics by including the electrode having excellent appearance characteristics and suppressing lithium salt precipitation while having a high capacity.

[0011]

[0012] [1] In one aspect, an electrode active material layer including an electrode active material, a conductive material, and a binder, wherein the electrode active material layer has A defined by the following equation 1 of 0.70 cm 2 ㎛ / mg or more, and the electrode active material has a specific surface area of ​​10 m 2 / g to 50 m 2 / g electrodes are provided.

[0013] [Formula 1]

[0014] A = [(W C x S C x D C ) / (W AM x S AM x L AM)] x 100

[0015] In the above equation 1, W C and W AM is the weight % of each conductive material and electrode active material relative to the total content of the electrode active material, conductive material, and binder, and S C and S AM are the BET surface areas (m) of the conductive material and electrode active material, respectively. 2 / g), and D C is the average particle diameter (㎛) of the challenge material, and L AM The loading amount of the electrode active material (mg / cm) 2 )am.

[0016] [2] In the electrode of the above [1], A is 0.70 cm 2 ㎛ / mg to 8.00 cm 2 It may be ㎛ / mg.

[0017] [3] In the electrode of the above [1] and / or [2], the conductive material has a specific surface area of ​​50 m 2 / g to 250 m 2 It could be / g.

[0018] [4] In at least one electrode among the above [1] to [3], the conductive material has an average particle diameter D 50 This may be 0.1 ㎛ to 4.0 ㎛.

[0019] [5] In at least one electrode among the above [1] to [4], the conductive material may include a dot-shaped conductive material.

[0020] [6] In at least one electrode among the above [1] to [5], the electrode active material may include at least one selected from the group consisting of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium composite transition metal oxide, and lithium iron phosphate compound.

[0021] [7] In at least one of the electrodes [1] to [6], the electrode active material may include a lithium iron phosphate compound.

[0022]

[0023] [8] In at least one electrode among the above [1] to [7], the electrode active material may be included in an amount of 93.0 wt% to 99.0 wt% based on the total weight of the electrode active material layer.

[0024] [9] In at least one electrode among the above [1] to [8], the conductive material may be included in an amount of 0.5 wt% to 5.0 wt% based on the total weight of the electrode active material layer.

[0025]

[0026]

[0010] In another aspect, a secondary battery including at least one electrode among [1] to [9] is provided.

[0027]

[0011] In the secondary battery of the above

[0010] , the electrode may be a positive electrode.

[0028]

[0029] The electrode according to this specification has an excellent appearance characteristic with an extremely low probability of occurrence of cracks or wrinkles on the surface by appropriately controlling the specific surface area and loading amount of the electrode active material and appropriately controlling the specific surface area and average particle diameter of the conductive material, and can have a large loading amount while having low electrode resistance.

[0030] In addition, the secondary battery according to the present specification has the advantage of having excellent capacity characteristics and solving the problem of lithium salt precipitation, thereby improving resistance characteristics by including the electrode as described above.

[0031]

[0032] 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 spirit 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 possible manner.

[0033] It should be understood that the terms “include,” “comprising,” or “having” used in this specification 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.

[0034] In this specification, "D 50 " means the particle size based on 50% of the volume cumulative particle size distribution of the positive electrode active material powder or conductive material in a dispersion state. The average particle diameter D 50 can be measured using a laser diffraction method. For example, after dispersing the positive electrode active material powder in a dispersion medium, it can be measured by introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasonic waves of about 28 kHz at an output of 60 W, obtaining a volume-cumulative particle size distribution graph, and then calculating the particle size corresponding to 50% of the volume-cumulative amount.

[0035] In this specification, “specific surface area (m 2 / g)” is measured by the BET method, and specifically, it can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using BELSORP-mino II of BEL Japan.

[0036]

[0037] Each of the electrodes and secondary batteries described herein includes at least one of the technical configurations described below, and may include any combination between technically possible configurations among the technical configurations below.

[0038]

[0039] electrode

[0040] In one aspect, the electrode includes an electrode active material layer including an electrode active material, a conductive material, and a binder, and the electrode active material layer has an A defined by factors such as the physical properties of the active material and the conductive material, which is 0.7 cm 2 ㎛ / mg or more, and the electrode active material has a specific surface area of ​​10 m 2 / g to 50 m 2 It is characterized by / g.

[0041] The electrode manufacturing process for secondary batteries involves applying an electrode slurry containing electrode materials to a current collector and then drying it. However, this drying process can cause pinholes, cracks, and wrinkles on the electrode surface as the solvent evaporates. These defects can cause lithium salts to precipitate on the surface or act as resistance, reducing output or rapid charging performance.

[0042] Although there may be various causes for cracks or wrinkles on the electrode surface, the main cause can be identified as an increase in the gap between the active materials due to solvent evaporation. The occurrence of cracks due to the gap between the active materials may be due to the conductive material not being properly arranged in the pores between the active materials. In order for the conductive material to be properly arranged in the pores between the active materials or on the surface of the active material, an appropriate relationship may be required between the number characteristics and length characteristics of the conductive material and the number characteristics of the active material.

[0043] This cracking process can begin during the slurry manufacturing process. For electrode active materials with large particle sizes and relatively small specific surface areas, the solids content can be easily increased, and drying does not pose any particular problems. However, when using electrode active materials with large specific surface areas and small particle sizes, the pore size is small, which can easily cause gaps between the electrode active materials during drying. This can lead to cracking problems and dispersibility issues due to the need for a larger amount of conductive material.

[0044] Due to the above issues, when using electrode active materials with large surface areas and small particle sizes, it is very difficult to increase the solids content due to dispersibility issues, and accordingly, the amount of solvent that must be evaporated inevitably increases. Therefore, the drying process can be performed under extremely harsh conditions, and as the above problems are combined with the problems caused by the harsh drying process, the possibility of cracking increases. Therefore, it can be said that there is a considerable demand for controlling the content, loading amount, and specific surface area of ​​the active material, as well as the specific surface area and particle size of the conductive agent.

[0045] Accordingly, the inventors of the present invention have defined A as defined by the above formula 1, which uses the properties of the active material and the conductive material as factors, based on the fact that when the relationship between the above properties is appropriately formed, the conductive material is evenly distributed on the surface of the active material, thereby suppressing an increase in the gap between the active materials due to evaporation of the solvent during the drying process, thereby preventing cracks or wrinkles from occurring on the electrode surface.

[0046]

[0047] A defined by Equation 1

[0048] In one aspect, the electrode active material layer has A defined by the following equation 1 as 0.70 cm 2 It is characterized by a density of ㎛ / mg or more.

[0049] [Formula 1]

[0050] A = [(W C x S C x D C ) / (W AM x S AM x L AM )] x 100

[0051] In the above equation 1, W C and W AM is the weight % of each conductive material and electrode active material relative to the total content of the electrode active material, conductive material, and binder, and S C and S AM are the BET surface areas (m) of the conductive material and electrode active material, respectively. 2 / g), and D C is the average particle diameter (㎛) of the challenge material, and L AM The loading amount of the electrode active material (mg / cm) 2 )am.

[0052] The above A may refer to the length or volume of the conductive material in contact with the surface of the electrode active material per unit weight of the electrode active material, as can be inferred from the unit. That is, the larger the value of A, the higher the proportion of the conductive material in good contact with the surface of the active material, which may mean that an excellent conductive network is formed and that cracks or wrinkles caused by solvent evaporating during drying can be prevented. Accordingly, in order to achieve the above effect, the above A may refer to 0.70 cm 2 It is necessary to satisfy ㎛ / mg or more, and preferably, 0.75 cm 2 ㎛ / mg or more, 0.79 cm 2 ㎛ / mg or more, 0.85 cm 2 ㎛ / mg or more, 0.86 cm 2 ㎛ / mg or more, 0.95 cm 2 ㎛ / mg or more, 1.00 cm 2 ㎛ / mg or more, 1.03 cm 2 ㎛ / mg or more, 1.10 cm 2 ㎛ / mg or more, 1.13 cm 2㎛ / mg or more or 1.20 cm 2 It may be ㎛ / mg or more. The above A is 0.70 cm 2 If it is smaller than ㎛ / mg, it may mean that the specific surface area of ​​the conductive material is too small compared to the average particle size and not enough particles are provided to cover the surface of the active material, or that the rolling pressure is too high and the loading amount of the active material is excessive, causing the internal structure to collapse, or that the specific surface area of ​​the active material is relatively large and there is a concern that a side reaction may occur with the secondary electrolyte.

[0053] The above A may mean that the larger the value, the better the conductivity and the better the appearance characteristics can be secured. However, if the value increases excessively, it may mean that the surface of the electrode active material is excessively covered with the conductive material, or that the conductive material is filling the voids within the electrode. In this case, the cycle life may be reduced beyond the effect of preventing cracks or wrinkles in the electrode, which may have the adverse effect of causing a decrease in the cycle life, and a decrease in capacity may occur due to a decrease in the amount of the active material. Considering this, the above A is preferably 8.00 cm 2 ㎛ / mg or less, 7.75 cm 2 ㎛ / mg or less, 7.69 cm 2 ㎛ / mg or less, 7.50 cm 2 ㎛ / mg or less, 7.30 cm 2 ㎛ / mg or less, 7.00 cm 2 ㎛ / mg or less, 6.80 cm 2 ㎛ / mg or less, 6.50 cm 2 ㎛ / mg or less, 6.30 cm 2 ㎛ / mg or less, or 6.00 cm 2 It may be less than ㎛ / mg.

[0054] In order for the conductive material to be in good contact with the surface of the electrode active material within the electrode active material layer, the number characteristics (specific surface area) of the electrode active material and the conductive material need to be appropriately controlled, and the length characteristics (average particle diameter) of the conductive material need to be considered together with the number characteristics.

[0055] In this respect, as in the above equation 1, the specific surface area and loading amount of the electrode active material, the specific surface area and average particle diameter of the conductive material are included as factors, and the contents of the electrode active material and the conductive material are also considered together. If the relationship between the above factors is adjusted so that the value of A can be satisfied within the above-mentioned range, the occurrence of cracks and wrinkles in the electrode can be prevented, thereby preventing a decrease in lifespan due to lithium salt precipitation or a decrease in output due to an increase in cell resistance.

[0056] In other words, rather than the specific surface area and loading amount of the electrode active material and the specific surface area and average particle size of the conductive material each having individual technical meanings, they can have a technical meaning in that the specific surface area and average particle size of the conductive material can be appropriately selected to prevent the occurrence of cracks or wrinkles on the electrode, and excellent appearance characteristics of the electrode to be manufactured can be secured through the selection of an electrode active material that matches this. In the case of such an electrode, there is an advantage in that a secondary battery with improved life performance and resistance characteristics can be provided.

[0057]

[0058] electrode active material

[0059] In one aspect, the electrode active material layer includes an electrode active material, a conductive material, and a binder. The electrode active material may be a positive electrode active material or a negative electrode active material.

[0060] The specific surface area of ​​the electrode active material, which is one of the factors defining the above A, is 10 m 2 / g to 50 m 2 / g is characterized by. Preferably 12 m 2 / g or more, 14 m 2 / g or more, 16 m 2 / g or more, 18 m 2 / g or more, or 20 m 2 / g may be higher. Also, 45 m 2 / g or less, 43 m 2 / g or less, 40 m 2 / g or less, 35 m 2 / g or less, 33 m 2 / g or less, or 30 m 2 / g can be less.

[0061] When the specific surface area of ​​the electrode active material is as above, cracks occurring on the electrode surface or side reactions with the electrolyte, etc., expected from the A value defined by the above formula 1, can be optimally evaluated. When the specific surface area of ​​the electrode active material is small, the need for the above formula A is significantly reduced, and this is because, as described above, the problems of electrode active materials with a large specific surface area occurring during the slurry manufacturing process and drying process, for example, the problems occurring in electrode active materials with a specific surface area of ​​about 10 m2 / g or more, do not occur at all.

[0062] On the other hand, applying an electrode active material with a specific surface area within the above range can reduce restrictions in selecting the specific surface area and average particle size of the conductive material, and provide an environment in which the conductive material can be evenly distributed on the surface of the active material. Furthermore, side reactions with the electrolyte can be appropriately controlled, while ensuring a certain level of lithium ion mobility (kinetics) at the interface between the positive electrode active material and the electrolyte.

[0063] In addition, the loading amount of the electrode active material is 18 mg / cm 2 30 mg / cm 2 may be, preferably 19 mg / cm 2 Above, 20 mg / cm 2 It may be more than 28 mg / cm 2 Below, 26 mg / cm 2 or less, or 24 mg / cm 2 The loading amount may be a level to secure a minimum capacity and prevent the electrode from being damaged during the rolling process and to prevent the electrode thickness from becoming too thick or the porosity from becoming too high, and it may be desirable to control it within the aforementioned range.

[0064]

[0065] The above electrode active material may be a positive electrode active material, and the positive electrode active material may include, for example, at least one selected from the group consisting of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium composite transition metal oxide, and lithium iron phosphate compound.

[0066] The above lithium composite transition metal oxide is, for example, a lithium-nickel-manganese oxide (e.g., LiNi 1-Y Mn Y O2 (here, 0 <Y<1), LiMn 2-Z Ni Z O4 (where 0<Z<2), etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1 Co Y1 O2 (here, 0 <Y1<1) 등), 리튬-망간-코발트계 산화물(예를 들면, LiCo 1-Y2 Mn Y2 O2 (here, 0 <Y2<1), LiMn 2-Z1 Co Z1 O4 (wherein, 0<Z1<2) etc.), lithium-nickel-manganese-cobalt oxides (e.g., Li(Ni p Co q Mn r )O2(wherein, 0<p<1, 0<q<1, 0<r<1, p+q+r=1) or Li(Ni p1 Co q1 Mn r1 )O4 (wherein, 0<p1<2, 0<q1<2, 0<r1<2, p1+q1+r1=2) etc.), or lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r2 M s2)O2 (wherein, M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg and Mo, and p2, q2, r2 and s2 are atomic fractions of independent elements, respectively, 0<p2<1, 0<q2<1, 0<r2<1, 0<s2<1, p2+q2+r2+s2=1), etc.) etc. The lithium iron phosphate compound may include, for example, Li 1+a Fe 1-x M x (PO 4-b )X b (Here, M is at least one selected from Al, Mg, and Ti, X is at least one selected from F, S, and N, and -0.5≤a≤0.5, 0≤x≤0.5, 0≤b≤0.1) may be a compound represented by the above. The positive electrode active material may include at least one compound selected from the compounds described above.

[0067] The above-described positive electrode active material may preferably include a lithium iron phosphate compound. When the positive electrode active material is a lithium iron phosphate compound, it is expected that an electrode without cracks can be manufactured with high reproducibility by utilizing the above-described A value. In the case of a lithium iron phosphate compound, it is an active material with a large specific surface area and a small particle size, and furthermore, it is an active material with low electrical conductivity, and thus requires a larger amount of conductive material, making it difficult to increase the solid content, difficult to disperse, and highly likely to cause cracks due to widening of the gap between active materials. Accordingly, the positive electrode active material may preferably include a lithium iron phosphate compound.

[0068]

[0069] The above electrode active material may be a negative electrode active material, and the negative electrode active material may include at least one selected from the group consisting of lithium metal, a carbon material capable of reversibly intercalating / deintercalating lithium ions, a metal or an alloy of these metals and lithium, a metal composite oxide, a material capable of doping and dedoping lithium, and a transition metal oxide.

[0070] As the carbon material capable of reversibly intercalating / deintercalating the lithium ions, any carbon-based negative electrode active material commonly used in lithium-ion secondary batteries can be used without particular limitation, and representative examples thereof include crystalline carbon, amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical, or fibrous form, and examples of the amorphous carbon include soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, etc.

[0071] As the above metal or an alloy of these metals with lithium, a metal selected from the group consisting of Cu, Ni, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al and Sn or an alloy of these metals with lithium may be used.

[0072] The above metal composite oxides include PbO, PbO2, Pb2O3, Pb3O4, Sb2O3, Sb2O4, Sb2O5, GeO, GeO2, Bi2O3, Bi2O4, Bi2O5, Li x Fe2O3(0≤x≤1), Li x WO2(0≤x≤1) and Sn x Me 1-x Me' y O z(Me: Mn, Fe, Pb, Ge; Me': Al, B, P, Si, elements of group 1, 2, and 3 of the periodic table, halogens; 0 <x≤1; 1≤y≤3; 1≤z≤8) 로 이루어진 군에서 선택되는 것이 사용될 수 있다.

[0073] Materials capable of doping and dedoping the above lithium include Si, SiO x (0 <x≤2), Si-Y 합금(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Si은 아님), Sn, SnO2, Sn-Y(상기 Y는 알칼리 금속, 알칼리 토금속, 13족 원소, 14족 원소, 전이금속, 희토류 원소 및 이들의 조합으로 이루어진 군에서 선택되는 원소이며, Sn은 아님) 등을 들 수 있고, 또한 이들 중 적어도 하나와 SiO2를 혼합하여 사용할 수도 있다. 상기 원소 Y로는 Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ge, P, As, Sb, Bi, S, Se, Te, Po 및 이들의 조합으로 이루어진 군에서 선택될 수 있다.

[0074] Examples of the above transition metal oxides include lithium-containing titanium composite oxide (LTO), vanadium oxide, and lithium vanadium oxide.

[0075] The electrode active material may comprise 85 wt% to 99 wt% based on the total weight of the electrode active material layer, preferably 88 wt% or more, 90 wt% or more, 91 wt% or more, or 93 wt% or more, and may also be comprised at 98.5 wt% or less, 98 wt% or less, or 97 wt% or less. When comprised within the above range, it may be preferable in terms of both increasing the capacity and energy density of the electrode and optimizing the functions of the conductive material and binder, which are auxiliary materials.

[0076]

[0077] Challenge

[0078] In one aspect, the electrode active material layer includes an electrode active material, a conductive material, and a binder. The conductive material may include a linear conductive material and / or a dot-shaped conductive material.

[0079] The linear conductive material may include a single-walled carbon nanotube and / or a multi-walled carbon nanotube, and preferably, a multi-walled carbon nanotube may be applied, in which case, the specific surface area and D of an appropriate value to satisfy the above-mentioned A 50 can be applied.

[0080] In addition, the dot-shaped conductive material may include carbon black, and may include, for example, at least one selected from the group consisting of acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black.

[0081] The above conductive material has a great influence on defining A, and it is desirable that the specific surface area be controlled within an appropriate range. When a conductive material that satisfies the specific surface area range below, independently of the shape of the conductive material, such as a linear conductive material and a point-shaped conductive material, is applied, an electrode that satisfies the range of the A value can be more easily implemented.

[0082] The specific surface area of ​​the above challenge material is 50 m 2 / g to 250 m 2 / g, and can be measured by the BET method, specifically, it can be calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77K) using BELSORP-mino II of BEL Japan. Preferably, 65 m 2 / g or more, 75 m 2 / g or more, 80 m 2 / g or more, 85 m 2 / g or more, 90 m 2 / g or more, 95 m 2 / g or more, or 100 m 2 / g can be more than 240 m 2 / g or less, 230 m 2 / g or less, 220 m 2 / g or less, 210 m 2 / g or less, 205 m 2 / g or less, or 200 m 2 / g can be less.

[0083] Similar to the above surface area, and independently, it is preferable that the average particle diameter of the conductive material be controlled within an appropriate range, and when a conductive material that satisfies the average particle diameter range below, independently of the shape of the conductive material, such as a linear conductive material and a dot-shaped conductive material, is applied, an electrode that satisfies the range of the A value can be more easily implemented.

[0084] The average particle diameter D of the above challenge material 50 The average particle size of the conductive material may be 0.1 ㎛ to 4.0 ㎛, 0.5 ㎛ or more, 0.7 ㎛ or more, 0.9 ㎛ or more, or 1.0 ㎛ or more, 3.5 ㎛ or less, 3.3 ㎛ or less, 3.0 ㎛ or less, 2.8 ㎛ or less, or 2.6 ㎛ or less. Here, the average particle size D of the conductive material 50The conductive material dispersion may refer to the average particle diameter in a dispersion state in which conductive material powder is dispersed in an organic solvent, and may be measured using a laser diffraction method, and may refer to the average particle diameter at 50% of volume accumulation in a volume accumulation distribution graph obtained from the measurement. In addition, the conductive material dispersion may have a conductive material content of 1 wt% to 20 wt%, preferably 1.5 wt% or more, 2.0 wt% or more, and may also be a dispersion having a conductive material content of 15 wt% or less, 12 wt% or less, or 10 wt% or less.

[0085] The specific surface area of ​​the above conductive material is a property that can represent the number characteristics of the conductive material, and the average particle diameter of the above conductive material is a property that can represent the length characteristics of the conductive material. When these two properties are controlled simultaneously, it can be expected that the conductive material will be well arranged between the surface and pores of the active material.

[0086] The conductive agent may be included in an amount of 0.01 wt% to 6.0 wt% based on the total weight of the electrode active material layer. Preferably, it may be included in an amount of 0.05 wt% or more, 0.1 wt% or more, 0.15 wt% or more, 0.2 wt% or more, 0.3 wt% or more, 0.5 wt% or more, 0.7 wt% or more, 0.9 wt% or more, or 1.0 wt% or more, and may also be included in an amount of 5.7 wt% or less, 5.5 wt% or less, 5.3 wt% or less, or 5.0 wt% or less. The conductive agent may be advantageous for forming a conductive path as the amount of the conductive agent increases, but the capacity may be lowered due to a relative decrease in the amount of the active material, and when the conductive agent is applied while being adjusted within the above range, an appropriate level of A value may be satisfied, so it may be preferable to apply the conductive agent within the above range.

[0087]

[0088] Electrode guitar

[0089] In one aspect, the electrode includes a binder. The binder serves to improve adhesion between electrode active material particles and adhesion between the electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinylalcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, polyacrylic acid, and polymers in which hydrogens of these are substituted with Li, Na, or Ca, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The binder may be included in an amount of 0.1 wt% to 10 wt% based on the total weight of the electrode active material layer, preferably 0.3 wt% or more, 0.5 wt% or more, 0.7 wt% or more, or 1.0 wt% or more, and may also be 9.0 wt% or less, 8.5 wt% or less, 8.0 wt% or less, 7.5 wt% or less, 7.0 wt% or less, or 6.5 wt% or less.

[0090]

[0091] In one aspect, the electrode may further include a current collector, and the electrode active material layer may be disposed on the current collector.

[0092] If the electrode is a positive electrode, the current collector may include a highly conductive metal, and is not particularly limited as long as it is one to which the positive electrode active material layer can be easily adhered, but is not reactive within the voltage range of the battery. For example, the positive electrode current collector may be made of stainless steel, aluminum, nickel, titanium, heat-treated carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc.

[0093] In addition, the thickness of the current collector may be 3 ㎛ to 100 ㎛, preferably 8 ㎛ to 80 ㎛, but is not limited thereto. Fine unevenness may be formed on the surface of the current collector to increase the adhesion of the 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.

[0094] When the above electrode is a negative electrode, the current collector is not particularly limited as long as it has high conductivity without causing changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used.

[0095] In addition, the thickness of the current collector may be 3 ㎛ to 100 ㎛, preferably 8 ㎛ to 80 ㎛, but is not limited thereto. Fine unevenness may be formed on the surface of the current collector to increase the adhesion of the 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.

[0096] The current collector may be a metal foil as described above, but a composite current collector having a structure in which a resin is interposed between metal thin films may also be applied, and the thickness of the composite current collector may also be selected within the range described above, and the resin may be a polyester-based resin, a polyolefin-based resin, or a polyacrylic-based resin.

[0097]

[0098] Method for manufacturing electrodes

[0099] In one aspect, a step (S1) of applying an electrode slurry including an electrode active material, a conductive material, and a binder onto a current collector; and a step (S2) of drying and rolling the electrode slurry on the current collector; wherein A defined by the following formula 1 is 0.70 cm 2 The above S1 and S2 steps are performed so that the electrode active material has a specific surface area of ​​10 m 2 / g to 50 m 2 A method for manufacturing an electrode of / g is provided.

[0100] [Formula 1]

[0101] A = [(W C x S C x D C ) / (W AM x S AM x L AM )] x 100

[0102] In the above equation 1, W C and W AM is the weight % of each conductive material and electrode active material relative to the total content of the electrode active material, conductive material, and binder, and S C and S AM are the BET surface areas (m) of the conductive material and electrode active material, respectively. 2 / g), and D C is the average particle diameter (㎛) of the challenge material, and L AM The loading amount of the electrode active material (mg / cm) 2 )am.

[0103] Since the description of A defined by the above formula 1 and the description of the factors included in A have been described in the description of the electrode, a detailed description is omitted.

[0104] The above step S1 may be a step of selecting an electrode active material and a conductive material having appropriate properties so that A can be satisfied, and mixing them together with a binder in an organic solvent.

[0105] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethyl formamide (DMF), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant 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 positive electrode.

[0106] The above step S2 may be a step of adjusting the loading amount of the electrode active material in the electrode active material layer formed by drying and rolling the electrode slurry applied to the current collector of step S1 so that A can be satisfied to a target range.

[0107]

[0108] secondary batteries

[0109] In another aspect, a secondary battery including the electrode is provided, and preferably, the electrode may be a positive electrode.

[0110] The secondary battery may include a non-aqueous electrolyte secondary battery including a liquid electrolyte, or an all-solid-state secondary battery including a solid electrolyte, and may also include a lithium secondary battery in which charging and discharging occur by the movement of lithium ions and electrons, or a sodium secondary battery in which charging and discharging occur by the movement of sodium ions and electrons. However, the following description will be given using a lithium secondary battery as an example.

[0111] If the secondary battery is a non-aqueous electrolyte secondary battery, it includes a positive electrode, a negative electrode positioned opposite the positive electrode, and a separator and electrolyte interposed between the positive electrode and the negative electrode. Since the electrode is the same as described above, a detailed description is omitted, and only the remaining components are described in detail below.

[0112] The secondary battery may optionally further include a battery container that houses the electrode assembly of the positive electrode, negative electrode, and separator, and a sealing member that seals the battery container.

[0113] In the above secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. 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 absorption 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 to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0114]

[0115] Examples of the electrolyte include, but are 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 secondary batteries.

[0116] The electrolyte may include an organic solvent and a lithium salt.

[0117] As the organic solvent, any solvent 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, the organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-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 dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); Alcohol solvents such as ethyl alcohol, isopropyl alcohol, etc.; nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes, etc. can be used. Among these, carbonate solvents are preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of a battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferable.

[0118] The above lithium salt can be used without any special limitation as long as it is a compound that can provide lithium ions used in secondary batteries. Specifically, the anion of the above lithium salt is F - , Cl - , Br - , I - , NO3 - , N(CN)2 - , BF4 - , CF3CF2SO3 - , (CF3SO2)2N - , (FSO2)2N - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (CF3SO2)3C - , CF3(CF2)7SO3 - , CF3CO2 - , CH3CO2 - , SCN - and (CF3CF2SO2)2N - At least one selected from the group consisting of, and the lithium salt is LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2) 2. LiCl, LiI, or LiB(C2O4)2 can be used. It is recommended that the concentration of the lithium salt be within the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0119] 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. At this time, the additives may be included in an amount of 0.1 to 5 wt% based on the total weight of the electrolyte.

[0120]

[0121]

[0122] *If the secondary battery is an all-solid-state secondary battery, it includes an electrode assembly including a unit cell in which a positive electrode, a solid electrolyte membrane, and a negative electrode are sequentially laminated, and at least one of the positive electrode and the negative electrode may include the electrode current collector of the present invention described above. The all-solid-state secondary battery includes a solid electrolyte as a main component of the solid electrolyte membrane, but may also include it in the electrode composite layer of the positive electrode or the negative electrode, and the components of the solid electrolyte and the solid electrolyte membrane included in the electrode composite layer may be the same or different, but it is preferable to use the same ones.

[0123] In the above secondary battery, the description of the electrode is the same as that described above, so its description is omitted.

[0124]

[0125] As the above solid electrolyte, for example, a halide-based solid electrolyte, an oxide-based solid electrolyte, a polymer-based solid electrolyte, or a sulfide-based solid electrolyte can be used, and in particular, a sulfide-based solid electrolyte can be preferably used.

[0126] The above sulfide-based solid electrolyte may include a solid electrolyte represented by the following chemical formula 1:

[0127] [Chemical Formula 1]

[0128] Li x M y P z S v A w

[0129] In the above chemical formula 1, x, y, z, v, and w are independently 0 to 7, and can be determined so that the total charge is neutral, M is at least one of As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta, and A is at least one of F, Cl, Br, or I.

[0130] The above sulfide-based solid electrolyte is a representative sulfide-based solid electrolyte having an argyrodite structure, which has a high Li+ mobility and a cubic phase at high temperatures with improved ionic conductivity, and can be stabilized by replacing sulfur with a halogen anion. As the halogen element is substituted, a vacancy is formed at the Li-site portion within the argyrodite unit cell, thereby improving Li ion conductivity, and due to this substitution of the halogen ion, the cubic structure can be stabilized even at room temperature.

[0131] For example, the above sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n(m and n are positive numbers, Z is one of Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2SSiS2-Li p MO q (p and q are positive numbers, M is one of P, Si, Ge, B, Al, Ga or In), or a combination thereof. The solid electrolyte may be composed of one material selected from these sulfide-based solid electrolyte materials, or may be composed of two or more materials. Preferably, one including Li2S-P2S5 can be used. When one including Li2S-P2S5 is used as the sulfide-based solid electrolyte material, the mixing molar ratio of Li2S and P2S5 can be selected in the range of, for example, Li2S:P2S5=50:50 to 90:10.

[0132] The solid electrolyte may be included in an amount of 1 wt% to 30 wt% based on the total weight of the electrode composite layer, preferably 3 wt% or more, 5 wt% or more, 7 wt% or more, or 10 wt% or more, and may also be included in an amount of 25 wt% or less, 20 wt% or less, or 15 wt% or less.

[0133]

[0134] battery box

[0135] In another aspect, a battery box comprising a plurality of secondary batteries is provided. The battery box may comprise a plurality of secondary batteries and a packaging housing the plurality of secondary batteries. Here, the battery box may be, for example, a battery module or a battery pack.

[0136] Since the above secondary battery stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it can be usefully used in portable devices such as mobile phones, laptops, and digital cameras, and electric vehicles such as full electric vehicles (FEVs) and hybrid electric vehicles (HEVs).

[0137] The above battery box can be used as one or more power devices selected from the group consisting of a power tool; an electric vehicle including a full electric vehicle (FEV), a hybrid electric vehicle (HEV), and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0138] According to the present specification, in another aspect, an electrical device including the battery box and included as a power supply may be provided.

[0139]

[0140] Example

[0141] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0142]

[0143] Example 1-1

[0144] A slurry was prepared by mixing 95 parts by weight of lithium iron phosphate (LiFePO4), 3 parts by weight of carbon nanotubes, and 2 parts by weight of polyvinylidene difluoride (PVDF) in an N-methyl pyrrolidone solvent, and the slurry was then applied to an aluminum foil current collector using a slot die coater. Thereafter, the slurry applied to the current collector was dried at 130°C to prepare an electrode.

[0145]

[0146] Examples 1-2 to 1-8 and Comparative Examples 1-1 to 1-6 were manufactured by applying the contents and loading amounts described using positive electrode active materials and conductive materials having the properties described in Table 1 below, and Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-5 were manufactured by applying the properties, contents and loading amounts described in Table 2 below, respectively.

[0147]

[0148] Active material, conductive material A content (weight%), specific surface area (m 2 / g) Loading amount (mg / cm) 2 ) Type Content (weight%) Specific surface area (m 2 / g)D 50 (㎛)Example 1-1952020CNT310010.79Example 1-2932020CNT510011.34Example 1-3972020CNT120021.03Example 1-4952020CNT320023.16Example 1-5932020CNT520025.38Example 1-6932520CNT510011.08Example 1-7912020CNT720027.69Comparative Example 1-1972020CB13000.050.04Comparative Example 1-2952020CB33000.050.12Comparative Example 1-3932020CB53000.050.20Comparative Example 1-4972020CNT110010.26Comparative Example 1-5952520CNT310010.63Comparative Example 1-6956020CNT310010.26

[0149] Active material, conductive material A content (weight%), specific surface area (m 2 / g) Loading amount (mg / cm) 2) Type Content (weight%) Specific surface area (m 2 / g)D 50 (㎛)Example 2-1932024CNT510011.12Example 2-2972024CNT120020.86Example 2-3952024CNT320022.63Example 2-4932024CNT520024.48Comparative Example 2-1972024CNT110010.21Comparative Example 2-2952024CNT310010.66Comparative Example 2-3972024CB13000.050.03Comparative Example 2-4952024CB33000.050.10Comparative Example 2-5932024CB53000.050.17

[0150] The particle size and specific surface area of ​​the above positive electrode active material and conductive material can be measured by the following methods. 1) D 50 (㎛) was measured by introducing a conductive material dispersed in N-methylpyrrolidone into a laser diffraction particle size measuring device (Microtrac MT 3000), irradiating it with ultrasonic waves of approximately 28 kHz at an output of 60 W, obtaining a volume-cumulative particle size distribution graph, and then calculating the particle size corresponding to 50% of the volume-cumulative amount.

[0151] 2) Specific surface area (m) 2 / g) was measured by the BET method and was calculated from the nitrogen gas adsorption amount at liquid nitrogen temperature (77 K) using BELSORP-mino II from BEL Japan.

[0152]

[0153] Experimental Example 1: Evaluation of Electrode Surface Characteristics

[0154] The surface of the anodes manufactured in the above examples and comparative examples was visually observed to check for the presence or absence of cracks.

[0155]

[0156] Experimental Example 2: Battery Performance Evaluation

[0157] 1) Manufacturing of secondary battery: An electrode assembly was manufactured by interposing a porous polyethylene separator between the positive and negative electrodes of the above examples and comparative examples, and then positioning this inside a case, and then injecting an electrolyte to manufacture a secondary battery.

[0158] At this time, the electrolyte was prepared by dissolving 1 M LiPF6 in an organic solvent with a volume ratio of ethylene carbonate / ethyl methyl carbonate / diethyl carbonate of 3:4:4, and the negative electrode was prepared as follows.

[0159] The above negative electrode was prepared by adding artificial graphite as a graphite-based active material, carbon black as a conductive material, and CMC:SBR as a binder to distilled water at a weight ratio of 95.6:1.0:1.1:2.3 to prepare a negative electrode slurry so that the solid content concentration was 45 wt%. The conductive material and binder were dispersed in water using a homogenous mixer at 2500 rpm for 30 min, and then the negative electrode active material was added and dispersed at 2500 rpm for 30 min. This method produced the negative electrode slurry.

[0160] The above negative electrode slurry was added to a copper current collector (thickness: 8㎛) as a negative electrode current collector at 10.0 mg / cm 2 The cathode was manufactured by coating with a loading amount, rolling (roll pressing), and drying in a vacuum oven at 130°C for 10 hours.

[0161] The secondary battery was charged to 4.2 V at a C-rate of 0.1 C and then discharged to 2.5 V to perform an activation process.

[0162] 2) Initial charge / discharge capacity (mAh): Charged to 4.2 V in CCCV mode at 0.33 C C-rate (cut-off 0.05 C), and discharged at 0.33 C and 2.5 V. The charge / discharge was performed three times each, and the capacity at the third discharge at 0.33 C and 2.5 V was measured as the initial capacity.

[0163] 3) Battery resistance (mΩ): After charging and discharging the secondary battery, and then fully charging and discharging it again, a 2.5C pulse current was applied for a specific period of time according to the change in SOC, and the battery resistance (10-second resistance) was measured.

[0164]

[0165] A Electrode Crack Battery Resistance (mΩ) Initial Capacity (mAh) Example 1-10.79 X 1.45 49.4 Example 1-21.34 X 1.35 48.0 Example 1-31.03 X 1.8 25 1.5 Example 1-43.16 X 1.28 49.8 Example 1-55.38 X 1.20 48.5 Example 1-61.08 X 1.5 3 48.7 Example 1-77.69 X 1.18 47.2 Comparative Example 1-10.04 X 2.3 1 49.8 Comparative Example 1-20.12 X 1.5 8 49.2 Comparative Example 1-30.20 X 1.37 47.8 Comparative Example 1-40.26 X 2.1 2 5 0.1 Comparative Example 1-50.63O1.7749.8Comparative example 1-60.26O1.7749.8

[0166] A Electrode Crack Battery Resistance (mΩ) Initial Capacity (mAh) Example 2-11.12X1.4558.2 Example 2-20.86X1.9260.8 Example 2-32.63X1.4560.3 Example 2-44.48X1.3959.1 Comparative Example 2-10.21O2.3360.5 Comparative Example 2-20.66O1.5160.1 Comparative Example 2-30.03O2.5960.2 Comparative Example 2-40.10O1.5759.8 Comparative Example 2-50.17O1.5058.0

[0167] Referring to Tables 3 and 4 above, the A value was adjusted to 0.7 cm by controlling the content by considering the loading amount and specific surface area of ​​the electrode active material and the average particle diameter and specific surface area of ​​the conductive material. 2Examples 1-1 to 1-7 and Examples 2-1 to 2-4, which were controlled to ㎛ / mg or more, confirmed that no cracks occurred after electrode manufacture, and that high capacity could be achieved while the battery resistance was generally low. On the other hand, Comparative Examples 1-1 to 1-3 applied a large specific surface area to cover the small average particle diameter of the conductive material, but the A value was 0.7 cm despite controlling the content with the active material. 2 It can be confirmed that cracks occurred in the electrode because it was less than ㎛ / mg. In addition, Comparative Example 1-4 was intended to see the effect of average particle diameter and specific surface area when a small amount of conductive material was added. Compared to Example 1-3 in which the same content was applied, it was confirmed that cracks occurred in the electrode and the resistance of the battery was measured to be high. Through this, it was confirmed that the specific surface area and average particle diameter should be controlled according to the conductive material content. In addition, Comparative Examples 1-5 and 1-6 changed the specific surface area of ​​the active material. It shows that when an active material with a large specific surface area is applied, if the specific surface area and average particle diameter of the conductive material are not controlled accordingly, cracks occur in the electrode and the battery resistance increases at the same time. In addition, when looking at Example 1-7 and Comparative Example 1-5, it can be confirmed that the occurrence of cracks on the electrode was different even though only the content was controlled under the same conditions, and through this, it can be confirmed that the content of the applied active material and conductive material, the specific surface area, etc. are closely related and affect the appearance characteristics and battery characteristics of the electrode, and it was confirmed that this can be implemented by controlling the A value. In addition, in the case of Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-5, which were tested by increasing the loading amount of the active material, the A value was also 0.7 cm 2It can be confirmed that the occurrence of cracks in the electrode differs depending on whether the satisfies ㎛ / mg or more, and that when a small amount of conductive material is included, the specific surface area and average particle size must be controlled, and when the average particle size of the conductive material is too small, it is difficult to form a conductive network even when a large specific surface area is applied, and the same results are shown as the tendencies in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-6.

Claims

1. Includes an electrode active material layer including an electrode active material, a conductive material, and a binder, The above electrode active material layer is defined by Equation 1 below, where A is 0.70 cm 2 ㎛ / mg or more, The above electrode active material has a specific surface area of ​​10 m 2 / g to 50 m 2 / g, electrode: [Formula 1] A = [(W C x S C x D C ) / (W AM x S AM x L AM )] x 100 In the above equation 1, W C and W AM is the weight % of each conductive material and electrode active material relative to the total content of the electrode active material, conductive material, and binder, and S C and S AM are the BET surface areas (m) of the conductive material and electrode active material, respectively. 2 / g), and D C is the average particle diameter (㎛) of the challenge material, and L AM The loading amount of the electrode active material (mg / cm) 2 )am.

2. In paragraph 1, The above A is 0.70 cm 2 ㎛ / mg to 8.00 cm 2 ㎛ / mg, electrode.

3. In paragraph 1, The above challenge material has a specific surface area of ​​50 m 2 / g to 250 m 2 / g, electrode.

4. In paragraph 1, The above challenge material has an average particle diameter D 50 An electrode having a size of 0.1 μm to 4.0 μm.

5. In paragraph 1, An electrode, wherein the conductive material comprises a dot-shaped conductive material.

6. In paragraph 1, An electrode, wherein the electrode active material comprises at least one selected from the group consisting of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium composite transition metal oxide, and lithium iron phosphate compound.

7. In paragraph 1, The electrode active material is an electrode comprising a lithium iron phosphate compound.

8. In paragraph 1, An electrode in which the electrode active material is included in an amount of 93.0 wt% to 99.0 wt% based on the total weight of the electrode active material layer.

9. In paragraph 1, An electrode in which the conductive material is included in an amount of 0.5 wt% to 5.0 wt% based on the total weight of the electrode active material layer.

10. A secondary battery comprising the electrode of paragraph 1.

11. In paragraph 10, The above electrode is a positive electrode, a secondary battery.