Method for predicting fast charging performance of cylindrical lithium secondary battery, cylindrical lithium secondary battery, and method for manufacturing same

Abstract

An embodiment of the present invention provides a method for predicting fast charging performance of a cylindrical lithium secondary battery comprising a positive electrode, a separator, a negative electrode, and an electrolyte, wherein the negative electrode comprises: a negative electrode current collector; and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, the method comprising determining the fast charging performance of the cylindrical lithium secondary battery using the diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, the porosity Pa of the negative electrode active material layer, the thickness Ta of the negative electrode, and the injection fraction finjection of the electrolyte.

Description

Method for predicting rapid charging performance of a cylindrical lithium secondary battery, cylindrical lithium secondary battery and method for manufacturing the same

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2024-0192033 filed with the Korean Intellectual Property Office on December 19, 2024, the entire contents of which are incorporated herein.

[0002] The present invention relates to a method for predicting the rapid charging performance of a cylindrical lithium secondary battery, a cylindrical lithium secondary battery, and a method for manufacturing the same.

[0003] Secondary batteries, which possess electrical characteristics such as high energy density and high applicability across product categories, are widely applied not only to portable devices but also to electric vehicles (EVs) and hybrid electric vehicles (HEVs) driven by electric power sources.

[0004] These secondary batteries are attracting attention as a new energy source for improving eco-friendliness and energy efficiency, as they not only have the primary advantage of being able to drastically reduce the use of fossil fuels but also the advantage of not generating any by-products from the use of energy.

[0005] In particular, lithium-ion batteries are gaining attention as power sources for electronic devices due to their lightweight nature and high energy density. Accordingly, active research and development efforts are underway to improve the performance of lithium-ion batteries.

[0006] In a lithium secondary battery, electrical energy is produced by oxidation and reduction reactions when lithium ions are inserted into or removed from the positive and negative electrodes, in a state where an organic or polymer electrolyte is charged between a positive electrode and a negative electrode composed of active materials capable of lithium ion intercalation and deintercalation.

[0007] Lithium-ion batteries can be classified into cylindrical, prismatic, and pouch types depending on the shape of the battery case. In particular, with the recent advancement of electric vehicle technology and the increasing demand for high-capacity batteries, the development and use of bulky large cylindrical secondary batteries are being considered.

[0008] While conventionally used small cylindrical batteries, such as 1865 or 2170 form factors, did not require high rapid charging performance, large cylindrical secondary batteries are applied to electric vehicles, making rapid charging characteristics critical. However, when rapid charging is performed at high voltage and a high C-rate, the electrolyte decomposes rapidly, potentially generating large amounts of gases such as CO2 and CH4, which increase the internal pressure of the battery. As the electrolyte is displaced due to this increased internal pressure, it becomes localized. Consequently, lithium ions that have migrated through the localized electrolyte concentrate in specific negative electrode regions, leading to a phenomenon called lithium plating (Li-plating), where lithium ions that could not be inserted into the negative electrode precipitate on the surface of the negative electrode.

[0009] In other words, due to high current density, lithium cannot be inserted into the interior of the anode, leading to lithium plating. This causes lithium to precipitate on the anode surface, and the accumulation of lithium byproduct layers degrades the rapid charge life characteristics. Consequently, lithium plating can cause battery degradation or ignition, posing a risk to the battery's lifespan and safety.

[0010] Therefore, there is an urgent need to develop lithium secondary batteries capable of improving rapid charging performance by effectively controlling the lithium plating phenomenon during rapid charging; to this end, research and development of technologies capable of accurately predicting and optimizing rapid charging performance is required.

[0011] The present invention aims to provide a method for predicting the rapid charging performance of a cylindrical lithium secondary battery having excellent lifespan characteristics and stability by preventing lithium plating during rapid charging, a cylindrical lithium secondary battery, and a method for manufacturing the same.

[0012] However, the technical problems that the present invention aims to solve are not limited to those described above, and other unmentioned problems will be clearly understood by those skilled in the art from the description of the invention below.

[0013] One embodiment of the present invention is a method for predicting the rapid charging performance of a cylindrical lithium secondary battery comprising a positive electrode, a separator, a negative electrode, and an electrolyte, wherein

[0014] The above cathode comprises a cathode current collector; and a cathode active material layer provided on at least one surface of the cathode current collector, and

[0015] The diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and the porosity P of the negative electrode active material layer. a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte. injection A method for predicting the rapid charging performance of a cylindrical lithium secondary battery is provided, comprising the step of verifying the rapid charging performance of the cylindrical lithium secondary battery using [the method].

[0016] One embodiment of the present invention is a cylindrical lithium secondary battery comprising a positive electrode, a separator, a negative electrode, and an electrolyte, wherein

[0017] The above cathode comprises a cathode current collector; and a cathode active material layer provided on at least one surface of the cathode current collector, and

[0018] The diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and the porosity P of the negative electrode active material layer. a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte.injection A cylindrical lithium secondary battery satisfying an F value of 13.5 or less in the following formula 1 containing , and a method for manufacturing the same are provided.

[0019] [Equation 1]

[0020]

[0021] The inventors have developed a rapid charging performance prediction method that can ensure excellent lifespan characteristics and safety by effectively preventing lithium plating during rapid charging of a cylindrical lithium secondary battery.

[0022] Specifically, the inventors conducted research to suppress the lithium plating phenomenon during rapid charging and to improve lifespan characteristics and safety. As a result, they confirmed the rapid charging performance of a cylindrical lithium secondary battery using the diameter (R) and height (h) of the cylindrical lithium secondary battery, the porosity of the negative electrode active material layer, the thickness of the negative electrode, and the injection fraction of the electrolyte. For example, when specific conditions are satisfied, they were able to suppress the localization of the electrolyte caused by gas generated during rapid charging, thereby minimizing the lithium plating phenomenon and significantly improving the rapid charging lifespan characteristics and safety.

[0023] Accordingly, even before manufacturing or completing a cylindrical lithium secondary battery, the diameter (R) and height (h) of the cylindrical lithium secondary battery, the porosity of the negative electrode active material layer, the thickness of the negative electrode, and the injection fraction of the electrolyte can be measured to predict the rapid charging performance of the secondary battery in advance, thereby reducing costs and time and improving productivity.

[0024] In addition, the cylindrical lithium secondary battery according to the present invention can have excellent lifespan characteristics and stability by preventing lithium plating during rapid charging.

[0025] Specifically, the cylindrical lithium secondary battery can predict rapid charging life characteristics in advance and improve lithium deposition and rapid charging life characteristics by defining and controlling parameters that reflect the porosity and thickness of the negative electrode active material layer, the injection fraction of the electrolyte, and the form factor, so that lithium does not degrade battery performance due to lithium plating on the electrode surface.

[0026] Furthermore, the above-mentioned cylindrical lithium secondary battery can be manufactured according to the method for manufacturing a cylindrical lithium secondary battery according to the present invention.

[0027] However, the advantageous effects obtainable through the present invention are not limited to those described above, and other unmentioned effects will be clearly understood by those skilled in the art from the description of the invention below.

[0028] The following drawings attached to this specification illustrate preferred embodiments of the present invention and serve to further enhance understanding of the technical concept of the present invention together with the detailed description of the invention provided below; therefore, the present invention should not be interpreted as being limited only to the matters described in such drawings.

[0029] Figure 1 is a figure showing the capacity retention rate (%) of a cylindrical lithium secondary battery according to one embodiment and a comparison state of the present invention.

[0030] FIG. 2 is a schematic diagram illustrating the form factor of a cylindrical lithium secondary battery according to one embodiment of the present invention.

[0031] The present invention will be described in more detail below.

[0032] Terms and words used in this specification and claims are not limited to their ordinary or dictionary meanings, and must be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0033] In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0034] Furthermore, when it is said that a part, such as a layer, is "above" or "on" another part, this includes not only the case where it is "directly above" the other part, but also the case where there is another part in between. Conversely, when it is said that a part is "directly above" another part, it means that there is no other part in between. Also, saying that a part is "above" or "on" a reference part means that it is located above or below the reference part, and it does not necessarily mean that it is located "above" or "on" facing the opposite direction of gravity.

[0035] In this specification, "porosity" refers to the ratio of pores present within a material, through which an electrolyte permeates and serves as a pathway for the transport of lithium ions.

[0036] The above "Porosity" is expressed as a percentage (%) of the ratio of pores to the total volume and can be obtained through the BET gas adsorption method or by the following Equation 1-1.

[0037] [Equation 1-1]

[0038] Porosity = 1 - Electrode Density (ED) / Solid Density (SCD)

[0039] The above electrode density (ED) can be calculated as the loading amount per unit area of ​​the electrode (mg / cm²) / electrode thickness (cm), and the electrode thickness is the thickness of the electrode active material layer excluding the thickness of the current collector, which can be measured with a micrometer, etc.

[0040] In this specification, the "Porosity" can be calculated using Equation 1-1.

[0041] One embodiment of the present invention is a method for predicting the rapid charging performance of a cylindrical lithium secondary battery comprising a positive electrode, a separator, a negative electrode, and an electrolyte, wherein

[0042] The above cathode comprises a cathode current collector; and a cathode active material layer provided on at least one surface of the cathode current collector, and

[0043] The diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and the porosity P of the negative electrode active material layer. a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte. injection A method for predicting the rapid charging performance of a cylindrical lithium secondary battery is provided, comprising the step of verifying the rapid charging performance of the cylindrical lithium secondary battery using [the method].

[0044] By including a step of verifying the rapid charging performance of the above-mentioned cylindrical lithium secondary battery, the rapid charging performance can be predicted and designed before the cylindrical lithium secondary battery is completed, thereby reducing costs and time for production and manufacturing and improving productivity.

[0045] In addition, based on the prediction of the rapid charging performance of the above-mentioned cylindrical lithium secondary battery, the cylindrical lithium secondary battery can suppress the lithium plating phenomenon during rapid charging and significantly improve lifespan characteristics and safety.

[0046] In one embodiment of the present invention, the step of confirming the rapid charging performance of the cylindrical lithium secondary battery is the thickness T of the negative electrode. a and f, which is the injection fraction of the above electrolyte. injection P, which is the porosity of the above-mentioned cathode active material layer for . a Uses the ratio of.

[0047] In one embodiment of the present invention, the step of confirming the rapid charging performance of the cylindrical lithium secondary battery comprises the diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and the porosity P of the negative electrode active material layer. a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte. injection It includes a step of checking whether the F value of the following formula 1 containing is 13.5 or less.

[0048] [Equation 1]

[0049]

[0050] When a cylindrical lithium secondary battery is rapidly charged, the negative electrode expands due to the high current density, and the electrolyte inside the negative electrode is squeezed. At this time, the electrolyte moves toward the area of ​​lower pressure, and in particular, in the case of the electrode, there exists a region where the thickness becomes thinner due to the sliding region as it moves from the winding axis of the jelly roll toward both ends.

[0051] Due to the structural characteristics of the aforementioned secondary battery, empty spaces are formed at both ends. This results in a decrease in pressure in the corresponding region, causing the electrolyte to concentrate. This leads to localized reaction, causing localized lithium precipitation and degradation of rapid charging performance.

[0052] Therefore, by defining a parameter that can effectively control the displaced electrolyte as Equation 1 above and optimizing it, it is possible to predict and improve rapid charging performance and improve local lithium precipitation phenomena.

[0053] The method for predicting rapid charging performance for the above-mentioned cylindrical lithium secondary battery comprises the diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and P, which is the porosity of the negative electrode active material layer. a , the thickness T of the above cathodea , and f, which is the injection fraction of the above electrolyte. injection By including the step of checking whether the F value of Equation 1 above satisfies 13.5 or less, rapid charging performance can be predicted and designed before the cylindrical lithium secondary battery is completed, thereby reducing costs and time for production and manufacturing and improving productivity.

[0054] In addition, according to the prediction of the rapid charging performance of the above cylindrical lithium secondary battery, a cylindrical lithium secondary battery satisfying Equation 1 can suppress the lithium plating phenomenon during rapid charging and significantly improve lifespan characteristics and safety.

[0055] Specifically, the cylindrical lithium secondary battery can improve lithium deposition and rapid charging life characteristics by defining and controlling parameters that reflect the porosity of the negative electrode active material layer, the thickness of the negative electrode, the injection fraction of the electrolyte, and the form factor, so that lithium does not degrade battery performance due to lithium plating on the electrode surface.

[0056] In the present invention, the value of F in Equation 1 may be 13.3 or less, 13.1 or less, or 12.9 or less.

[0057] According to one embodiment of the present invention, if the calculation according to Equation 1 includes a decimal point, F in Equation 1 may be written up to the first decimal place by rounding to the second decimal place.

[0058] When the above range is satisfied, even if the electrolyte is squeezed as the cathode expands due to high current density during rapid charging, the amount of electrolyte pushed out of the electrode is minimized by controlling the electrolyte injection amount, thereby improving side reactions such as lithium deposition on the electrode surface and enhancing rapid charging life characteristics, and such rapid charging performance can be predicted.

[0059] The F value according to the above Equation 1 may be in μm / % units.

[0060] In the present invention, the porosity refers to the ratio of the volume occupied by actual pores to the electrode volume, and can be obtained by analyzing the pore distribution by BET analysis, that is, by adsorbing gas, or by calculating from Equation 1-1 above.

[0061] In the present invention, Ta(μm) represents the thickness of the cathode, which is a thickness including a cathode current collector and a cathode active material layer, and, for example, may be a thickness including a cathode current collector and a cathode active material layer provided on at least one surface of the cathode current collector.

[0062] The thickness of the above-mentioned cathode can be measured using a micrometer, a thickness gauge, or by observing a cross-sectional scanning electron microscope (SEM). Specifically, the cross-section of the cathode can be measured directly using a micrometer, or the total thickness including the current collector and the active material layer can be measured after capturing a cross-sectional image of the cathode using an SEM.

[0063] In the present invention, the thickness of the cathode can be measured with a micrometer, and the thickness of the cathode can be measured as the thickness of the electrode sampled after electrode manufacturing (coating, rolling, slitting).

[0064] f, the fraction of the above electrolyte injection solution injection represents the volume of the actual injected electrolyte relative to the pore volume of the cathode, anode, separator, and porous coating layer into which the electrolyte can be impregnated, as described below in Equation 2.

[0065] The above porous coating layer may be an SRS coating layer.

[0066] The above porous coating layer is a ceramic coating layer formed on the surface of a separator, and is thinly coated on the surface of the separator with a binder using inorganic materials such as alumina (Al2O3) or silica (SiO2), thereby preventing thermal shrinkage of the separator at high temperatures to improve the thermal stability of the cell, maintaining the pore structure of the separator, and improving heat resistance.

[0067] In this specification, "form factor" may refer to the ratio of the diameter (R) of the cylindrical lithium secondary battery to the height (h) of the cylindrical lithium secondary battery, with reference to FIG. 2.

[0068] The ratio of the diameter (R) of the cylindrical lithium secondary battery to the height (h) of the cylindrical lithium secondary battery (R / h, form factor ratio) may be 0.4 or more, preferably 0.4 to 0.6, and more preferably 0.5 to 0.6.

[0069] If the above range of form factor ratio is satisfied, high capacity characteristics can be realized as a large cylindrical lithium secondary battery.

[0070] According to one embodiment of the present invention, in a method for predicting the rapid charging performance of a cylindrical lithium secondary battery, the separator comprises a porous substrate and a porous coating layer provided on at least one surface of the porous substrate, and f, which is the injection fraction of the electrolyte. injection is calculated from the following Equation 2 or Equation 3, and f is the injection fraction of the electrolyte. injection It includes a step of checking whether it is 0.95 or greater and 1.05 or less.

[0071] [Equation 2]

[0072]

[0073] [Equation 3]

[0074]

[0075] In the above Equation 2 or Equation 3,

[0076] The above V ais the void volume of the negative electrode active material layer, and V c is the void volume of the positive active material layer, and V s is the pore volume of the separator, V srs is the pore volume of the porous coating layer, and V electrolyte is the volume of the electrolyte, and

[0077] The above delectrolyte is the density of the electrolyte, and the above M electrolyte is the mass of the electrolyte, and

[0078] The above l a is the length of the negative electrode active material layer, the above l c is the length of the positive active material layer, the above l s is the length of the separator, and the above l srs is the length of the porous coating layer, and

[0079] The above w a is the width of the negative electrode active material layer, and the above w c is the width of the positive active material layer, and the above w s is the width of the separator, and the above w srs is the width of the porous coating layer, and

[0080] The above t a is the thickness of the negative electrode active material layer, and the above t c is the thickness of the positive active material layer, and the above t s is the thickness of the separator, and the above t srs is the thickness of the porous coating layer, and

[0081] The above p a is the porosity of the negative electrode active material layer, and the above p c is the porosity of the positive active material layer, the above p s is the porosity of the separation membrane, and the above p srs is the porosity of the porous coating layer.

[0082] In a cylindrical lithium secondary battery, empty spaces may be formed at both ends from the winding axis of the jelly roll, and the electrolyte injected therein is injected into the void volumes of the negative electrode, positive electrode, separator, and porous coating layer, and the excess electrolyte remaining is locally accumulated at the ends of the jelly roll, so that the reaction is localized at the ends with a high concentration of lithium ions and lithium can be precipitated.

[0083] The above injection fraction refers to the volume of the actual injected electrolyte relative to the pore volume of the cathode, anode, separator, and porous coating layer into which the electrolyte can be impregnated, and by controlling and optimizing the above injection fraction, the rapid charging life characteristics can be improved.

[0084] The above injection fraction can be controlled by the amount of electrolyte injected, and the amount of electrolyte injected may refer to the amount (mass) of electrolyte actually injected into the secondary battery. Under conditions where other factors such as void volume are fixed, the injection fraction increases as the amount of electrolyte injected increases, and decreases as the amount of electrolyte injected decreases; therefore, the injection fraction can be controlled by controlling the amount of electrolyte injected.

[0085] According to one embodiment of the present invention, in the method for predicting the rapid charging performance of the cylindrical lithium secondary battery, the injection fraction of the electrolyte is f injection It is 0.95 or greater and 1.05 or less.

[0086] According to one embodiment of the present invention, when the calculation based on the injection fraction includes a decimal point, the injection fraction of the electrolyte is f injection It can be written up to the second decimal place by rounding to the third decimal place.

[0087] f, the fraction of the above electrolyte injection solution injection may be 0.95 or higher, 0.96 or higher, 0.97 or higher, or 0.98 or higher. f, which is the injection fraction of the above electrolyte. injection It may be 1.05 or less, 1.04 or less, 1.03 or less, 1.02 or less, 1.01 or less, or 1 or less.

[0088] When the above range is satisfied, lithium ions can be inserted into the negative electrode active material layer, and side reactions such as lithium plating (Li-plating) precipitating on the electrode surface are improved, thereby predicting the rapid charging performance of a cylindrical lithium secondary battery with improved rapid charging life characteristics.

[0089] In this specification, "pore volume" refers to the absolute volume of the empty space inside a material expressed in volume units (cm³, m³, etc.) to indicate the actual size of the pore, and can be obtained through the BET gas adsorption method (Micromeritics, Tristar II 3020).

[0090] In this specification, the length of the negative and positive active material layers refers to the length in the direction of the major axis of the active material layer, and the width of the negative and positive active material layers refers to the length in the direction of the minor axis of the active material layer.

[0091] The length, width, and thickness of the active material layer in the above electrode can be measured in micrometers, and can be measured based on the sampled state after the electrode manufacturing (coating, rolling, slitting), that is, based on the manufacturing date.

[0092] According to one embodiment of the present invention, in the method for predicting the rapid charging performance of the cylindrical lithium secondary battery, it is to check whether the value of F in Equation 1 satisfies 10 or more and 13.3 or less.

[0093] According to one embodiment of the present invention, the value of F in Equation 1 may be 10.0 or higher, 10.3 or higher, 10.5 or higher, 10.7 or higher, 10.3 or higher, 11.0 or higher, or 11.4 or higher.

[0094] According to one embodiment of the present invention, the value of F in Formula 1 may be 13.3 or less, 13.1 or less, 12.9 or less, 12.7 or less, or 12.3 or less.

[0095] When the above range is satisfied, even if the electrolyte is squeezed as the negative electrode expands due to high current density during rapid charging, the amount of electrolyte pushed out of the electrode is minimized by controlling the amount of electrolyte injected, thereby enabling lithium ions to be inserted into the negative electrode active material layer and improving side reactions such as lithium plating (Li-plating) precipitating on the electrode surface, so that the rapid charging performance of a cylindrical lithium secondary battery with improved rapid charging life characteristics can be predicted.

[0096] According to one embodiment of the present invention, in a method for predicting the rapid charging performance of the cylindrical lithium secondary battery, the T a (㎛) checks whether it satisfies 170 ㎛ or more and 188 ㎛ or less.

[0097] According to one embodiment of the present invention, the T a (㎛) may be 170 ㎛ or more, 171 ㎛ or more, 172 ㎛ or more, 173 ㎛ or more, 174 ㎛ or more, or 175 ㎛ or more.

[0098] According to one embodiment of the present invention, the T a (㎛) may be 188 ㎛ or less, or 187 ㎛ or less.

[0099] According to one embodiment of the present invention, in a method for predicting the rapid charging performance of the cylindrical lithium secondary battery, the P a (%) checks if it satisfies 23% or more and 26% or less.

[0100] According to one embodiment of the present invention, when the calculation based on the porosity includes a decimal point, the P a (%) can be written up to the first decimal place by rounding to the second decimal place.

[0101] According to one embodiment of the present invention, the P a (%) may be 23% or more, 24% or more, 25% or more, 25.5% or more, 25.6% or more, or 25.7% or more.

[0102] According to one embodiment of the present invention, the P a (%) may be 26% or less, 25.9% or less, or 25.8% or less.

[0103] The above T a When satisfying the ranges of (㎛) and Pa(%), lithium ions can be inserted into the negative electrode active material layer, and side reactions such as lithium plating (Li-plating) precipitating on the electrode surface are improved, thereby predicting the rapid charging performance of a cylindrical lithium secondary battery with improved rapid charging life characteristics.

[0104] According to one embodiment of the present invention, in the method for predicting the rapid charging performance of the cylindrical lithium secondary battery, the cylindrical lithium secondary battery satisfying that the F value of Equation 1 is 13.5 or less has a capacity retention rate (%) of 92% or more after 100 cycles of charging and discharging at 40°C at a 1C-rate.

[0105] According to one embodiment of the present invention, if the calculation based on the capacity retention rate (%) includes a decimal point, it may be written up to the first decimal place by rounding to the second decimal place.

[0106] The above cylindrical lithium secondary battery may have a capacity retention rate (%) of 92% or more, 92.5% or more, or 93% or more after 100 cycles of charging and discharging at 40°C at a 1C-rate.

[0107] The above cylindrical lithium secondary battery may have a capacity retention rate (%) of 98% or less, 97% or less, 96% or less, 95% or less, or 94.5% or less after 100 cycles of charge-discharge at 40°C at a 1C-rate. If the above cylindrical lithium secondary battery satisfies the above range, the rapid charging performance of the cylindrical lithium secondary battery with improved lithium deposition and rapid charging life characteristics can be predicted.

[0108] One embodiment of the present invention is a cylindrical lithium secondary battery comprising a positive electrode, a separator, a negative electrode, and an electrolyte, wherein the negative electrode comprises a negative electrode current collector; and a negative electrode active material layer provided on at least one surface of the negative electrode current collector.

[0109] The diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and the porosity P of the negative electrode active material layer. a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte. injection A cylindrical lithium secondary battery is provided that satisfies the condition that the F value of the following Formula 1 containing is 13.5 or less.

[0110] [Equation 1]

[0111]

[0112] Due to the structural characteristics of the secondary battery, empty spaces are formed at both ends of the winding axis of the jelly roll, which lowers the pressure in the area and causes the electrolyte to concentrate. This leads to localized reaction, causing localized lithium precipitation and degradation of rapid charging performance. Therefore, a parameter capable of effectively controlling the displaced electrolyte is defined by Equation 1 above, and by optimizing it, rapid charging performance can be predicted, improved, and localized lithium precipitation can be improved.

[0113] By satisfying the condition that the F value of Equation 1 above is 13.5 or less, the cylindrical lithium secondary battery can suppress the lithium plating phenomenon during rapid charging and significantly improve lifespan characteristics and safety.

[0114] In the present invention, the F value of Equation 1 may be 13.3 or less, 13.1 or less, or 12.9 or less, and when the above range is satisfied, even if the electrolyte is squeezed as the negative electrode expands due to high current density during rapid charging, the amount of electrolyte pushed out of the electrode is minimized by controlling the amount of electrolyte injected, thereby improving side reactions such as lithium deposition on the electrode surface and improving rapid charging life characteristics.

[0115] In one embodiment of the present invention, the separator comprises a porous substrate and a porous coating layer provided on at least one surface of the porous substrate, and the injection fraction (f) of the electrolyte injection ) is calculated from the following Equation 2 or Equation 3, and the injection fraction f of the electrolyte is calculated. injection The present invention provides a cylindrical lithium secondary battery having a value of 0.95 or higher and 1.05 or lower.

[0116] [Equation 2]

[0117]

[0118] [Equation 3]

[0119]

[0120] In the above Equation 2 or Equation 3,

[0121] The above V a is the void volume of the negative electrode active material layer, and V c is the void volume of the positive active material layer, and V s is the pore volume of the separator, V srs is the pore volume of the porous coating layer, and V electrolyte is the volume of the electrolyte, and

[0122] The above delectrolyte is the density of the electrolyte, and the above M electrolyte is the mass of the electrolyte, and

[0123] The above l a is the length of the negative electrode active material layer, the above l c is the length of the positive active material layer, the above ls is the length of the separator, and the above l srs is the length of the porous coating layer, and

[0124] The above w a is the width of the negative electrode active material layer, and the above w c is the width of the positive active material layer, and the above w s is the width of the separator, and the above w srs is the width of the porous coating layer, and

[0125] The above t a is the thickness of the negative electrode active material layer, and the above t c is the thickness of the positive active material layer, and the above t s is the thickness of the separator, and the above t srs is the thickness of the porous coating layer, and

[0126] The above p a is the porosity of the negative electrode active material layer, and the above p c is the porosity of the positive active material layer, the above p s is the porosity of the separation membrane, and the above p srs is the porosity of the porous coating layer.

[0127] According to one embodiment of the present invention, in a method for predicting the rapid charging performance of the cylindrical lithium secondary battery, the f injection It is 0.95 or greater and 1.05 or less.

[0128] The above f injection may be 0.95 or higher, 0.96 or higher, 0.97 or higher, or 0.98 or higher. The above f injection The value may be 1.05 or less, 1.04 or less, 1.03 or less, 1.02 or less, 1.01 or less, or 1.0 or less. When the above range is satisfied, lithium ions can be inserted into the negative electrode active material layer, and side reactions such as lithium plating (Li-plating) precipitating on the electrode surface can be improved, thereby enhancing rapid charging life characteristics.

[0129] According to one embodiment of the present invention, in the cylindrical lithium secondary battery, the value of F of Equation 1 is 10 or more and 13.3 or less.

[0130] According to one embodiment of the present invention, the value of F in Equation 1 may be 10.0 or higher, 10.3 or higher, 10.5 or higher, 10.7 or higher, 10.3 or higher, 11.0 or higher, or 11.4 or higher.

[0131] According to one embodiment of the present invention, the value of F in Formula 1 may be 13.3 or less, 13.1 or less, 12.9 or less, 12.7 or less, or 12.3 or less.

[0132] When the above range is satisfied, even if the electrolyte is squeezed as the negative electrode expands due to high current density during rapid charging, the amount of electrolyte pushed out of the electrode is minimized by controlling the amount of electrolyte injected, thereby allowing lithium ions to be inserted into the negative electrode active material layer and improving side reactions such as lithium plating (Li-plating) precipitating on the electrode surface, so that the rapid charging life characteristics can be improved.

[0133] According to one embodiment of the present invention, in the cylindrical lithium secondary battery, the T a (㎛) is 170 ㎛ or more and 188 ㎛ or less, and the above P a (%) is 23% or more and 26% or less, and the cylindrical lithium secondary battery has a capacity retention rate (%) of 92% or more after 100 cycles of charge and discharge at 40℃ at a 1C-rate.

[0134] In the above-mentioned cylindrical lithium secondary battery, the T a (㎛), P a As the details regarding (%) and capacity retention rate (%) are the same as described above, a detailed explanation is omitted.

[0135] According to one embodiment of the present invention, the invention comprises the steps of: manufacturing a jelly roll in which a positive electrode, a separator, and a negative electrode are laminated and wound; and manufacturing a cylindrical lithium secondary battery comprising a sealing body that encloses the jelly roll in a battery can, has an electrolyte, and seals the battery can, wherein the negative electrode comprises a negative electrode current collector; and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, wherein the diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and the porosity P of the negative electrode active material layer a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte. injection The present invention provides a method for manufacturing a cylindrical lithium secondary battery as described above, comprising the step of designing such that the F value of the following formula 1, including , satisfies 13.5 or less, and a cylindrical lithium secondary battery manufactured according to the same.

[0136] In the above method for manufacturing a cylindrical lithium secondary battery, the details regarding Formula 1 and the cylindrical lithium secondary battery are the same as those described above, so a detailed explanation is omitted.

[0137] According to one embodiment of the present invention, the anode can be manufactured by applying an anode slurry to one or both sides of a sheet-shaped anode current collector, removing the solvent of the anode slurry through a drying process, and then rolling.

[0138] Meanwhile, an anode including an uncoated portion can be manufactured by not applying the anode slurry to a portion of the anode current collector, for example, one end of the anode current collector, when applying the anode slurry.

[0139] In addition, the anode slurry can be prepared by dispersing the anode material according to the present invention in a solvent such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water.

[0140] The positive electrode manufactured accordingly comprises a positive electrode current collector; and a positive electrode active material layer, wherein the positive electrode active material layer may comprise a positive electrode active material.

[0141] Various positive current collectors used in the relevant technical field may be used as the positive current collector. For example, the positive current collector may be stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. The positive current collector may typically have a thickness of 3 to 500 μm, and fine irregularities may be formed on the surface of the positive current collector to increase the adhesion of the positive active material. The positive current collector may be used in various forms, such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0142] The positive active material layer may be located on the positive current collector, and specifically, may be located on one or both sides of the positive current collector. The positive active material layer may be a single layer or a multilayer structure of two or more layers.

[0143] The above-mentioned positive active material may be any positive active material commonly used in the relevant technical field, and its type is not particularly limited. The above-mentioned positive active material is a compound capable of reversible intercalation and deintercalation of lithium, and specifically, may include a lithium transition metal composite oxide comprising lithium and at least one transition metal composed of nickel, cobalt, manganese, and aluminum, preferably a lithium transition metal composite oxide comprising lithium and a transition metal comprising nickel, cobalt, and manganese.

[0144] More specifically, the lithium transition metal composite oxide includes a lithium-manganese oxide (e.g., LiMnO2, LiMn2O4, etc.), a lithium-cobalt oxide (e.g., LiCoO2, etc.), a lithium-nickel oxide (e.g., LiNiO2, etc.), and a lithium-nickel-manganese oxide (e.g., LiNi 1-Y MnYO2(here, 0 <Y<1), LiMn 2-z Ni z O4 (where 0 < Z < 2), etc.), lithium-nickel-cobalt oxides (e.g., LiNi 1-Y1CoY1 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 (where 0 < Z1 < 2), etc.), lithium-nickel-manganese-cobalt oxides (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 lithium-nickel-cobalt-transition metal (M) oxide (e.g., Li(Ni p2 Co q2 Mn r3 M S2Examples include )O2 (wherein M is selected from the group consisting of Al, Fe, V, Cr, Ti, Ta, Mg, and Mo, and p2, q2, r3, and s2 are each atomic fractions of independent elements, such that 0 < p2 < 1, 0 < q2 < 1, 0 < r3 < 1, 0 < s2 < 1, and p2 + q2 + r3 + s2 = 1), etc., and any one or more of these compounds may be included. Among these, the lithium transition metal composite oxide is LiCoO2, LiMnO2, LiNiO2, and 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, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2 or Li(Ni 0.8 Mn 0.1 Co 0.1 )O2, etc.), or lithium nickel-cobalt-aluminum oxide (e.g., Li(Ni 0.8 Co 0.15 Al 0.05 It may be )O2, etc., and considering the significant improvement effect resulting from controlling the type and content ratio of constituent elements forming the lithium transition metal composite oxide, the lithium transition metal composite oxide is Li(Ni 0.6 Mn 0.2 Co 0.2 )O2, Li(Ni 0.5 Mn 0.3 Co 0.2 )O2, Li(Ni 0.7 Mn 0.15 Co 0.15 )O2 or Li(Ni 0.8 Mn 0.1 Co 0.1 It may be O2, etc., and any one of these or a mixture of two or more may be used.

[0145] Meanwhile, the above-mentioned positive active material layer may optionally further include at least one of a positive conductive material and a positive binder.

[0146] The above-mentioned positive electrode conductive material is used to impart conductivity to the electrode, and in the battery being constructed, any material that possesses electronic conductivity without causing chemical changes can be used without any particular limitations. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, carbon nanotube; metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used. The above-mentioned positive electrode conductive material may typically be included in an amount of 1 to 30 weight%, preferably 1 to 20 weight%, and more preferably 1 to 10 weight% based on the total weight of the positive electrode active material layer.

[0147] The above-mentioned anode binder serves to improve adhesion between anode material particles and adhesion between the anode material and the anode current collector. Specific examples include fluoropolymer-based binders comprising polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE); rubber-based binders comprising styrene butadiene rubber (SBR), acrylonitrile-butadiene rubber, or styrene-isoprene rubber; cellulose-based binders comprising carboxyl methyl cellulose (CMC), starch, hydroxypropyl cellulose, or regenerated cellulose; polyalcohol-based binders comprising polyvinyl alcohol; polyolefin-based binders comprising polyethylene or polypropylene; polyimide-based binders; and polyester-based binders. Examples include silane-based binders, and one of these alone or a mixture of two or more may be used. The anode binder may be included in an amount of 1 to 30 weight%, preferably 1 to 20 weight%, and more preferably 1 to 10 weight% based on the total weight of the anode active material layer.

[0148] According to one embodiment of the present invention, the cathode can be manufactured by applying a cathode slurry to one or both sides of a sheet-shaped cathode current collector, removing the solvent of the cathode slurry through a drying process, and then rolling. Meanwhile, a cathode including an uncoated portion can be manufactured by not applying the cathode slurry to a portion of the cathode current collector, for example, one end of the cathode current collector, when applying the cathode slurry.

[0149] The above cathode slurry can be prepared by dispersing a cathode active material in a solvent such as distilled water, ethanol, methanol, or isopropyl alcohol.

[0150] Alternatively, the cathode may be manufactured by casting the cathode slurry onto a separate support and then laminating the film obtained by peeling off from the support onto a cathode current collector.

[0151] The cathode manufactured accordingly comprises a cathode current collector; and a cathode active material layer, and the cathode active material layer may comprise a cathode active material.

[0152] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical 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., and aluminum-cadmium alloy may be used. The above-mentioned negative current collector may typically have a thickness of 3 to 500 μm.

[0153] In addition, the above-mentioned negative current collector, like the positive current collector, may form fine irregularities on the surface of the current collector to strengthen the bonding force of the negative active material. For example, it can be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0154] The above negative electrode active material layer may be located on the negative electrode current collector, and specifically, may be located on one or both sides of the negative electrode current collector. The above negative electrode active material layer may be a single layer or a multilayer structure of two or more layers.

[0155] The thickness of the above-mentioned cathode active material layer may be 180㎛ to 200㎛, preferably 180㎛ to 190㎛, and more preferably 184㎛ to 190㎛. If the above range is satisfied, the capacity characteristics and lifespan characteristics can be improved.

[0156] The above-mentioned cathode active material may include a carbon-based active material. For example, the carbon-based active material may be one or more selected from the group consisting of amorphous, plate-like, flake-like, spherical, or fibrous natural graphite or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and petroleum or coal tar pitch-derived cokes.

[0157] Preferably, the negative electrode active material may be graphite and may include one or more selected from the group consisting of natural graphite and artificial graphite. When the negative electrode active material is included, capacity characteristics and lifespan characteristics may be improved.

[0158] The above-mentioned cathode active material may include artificial graphite and natural graphite, and in this case, the artificial graphite and natural graphite may be included in a ratio of 1:9 to 9:1, 2:8 to 8:2, 3:7 to 7:3, 4:6 to 6:4, or 5:5.

[0159] The above-mentioned negative electrode active material may be included in an amount of 90% to 99% by weight, preferably 93% to 99% by weight, and more preferably 96% to 99% by weight, based on the total weight of the negative electrode active material layer.

[0160] Meanwhile, the above-mentioned cathode active material layer may optionally further include a cathode conductive material and a cathode binder in addition to the cathode active material.

[0161] The above-mentioned cathode conductive material is used to impart conductivity to the electrode, and in the battery being constructed, it may be used without special limitations as long as it possesses electronic conductivity without causing chemical changes. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, carbon fiber, carbon nanotube; metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used. The above-mentioned cathode conductive material may typically be included in an amount of 1 to 30 weight%, preferably 1 to 20 weight%, and more preferably 1 to 10 weight% based on the total weight of the cathode active material layer.

[0162] The above-mentioned cathode binder serves to improve adhesion between cathode active material particles and adhesion between the cathode active material and the cathode current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene-butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used. The above-mentioned cathode binder may be included in an amount of 1 to 30 weight%, preferably 1 to 20 weight%, and more preferably 1 to 10 weight% based on the total weight of the cathode active material layer.

[0163] Since the thickness of the cathode, the porosity of the cathode active material layer, and the loading amount are the same as described above, a detailed explanation is omitted.

[0164] According to one embodiment of the present invention, the separator is interposed between the positive electrode and the negative electrode to separate the negative electrode and the positive electrode and to provide a pathway for the movement of lithium ions, and can be used without special limitations as long as it is used as a separator in a lithium secondary battery. Specifically, the separator may be a porous polymer film, for example, a porous polymer film made of a polyolefin-based 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. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fibers, polyethylene terephthalate fibers, etc., may be used. Furthermore, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength.

[0165] Meanwhile, the above anode and cathode have a structure in which an active material layer is formed on a sheet-shaped current collector, and may include an unactive portion in which an active material layer is not formed in a part of the current collector.

[0166] As described above, by using an anode and a cathode that include a non-electrode portion, a battery structure can be implemented in which at least a portion of the non-electrode portions of the anode and cathode defines an electrode tab without having to provide a separate electrode tab.

[0167] Specifically, the above-mentioned non-current portion can be formed lengthwise along the winding direction (X) at one end of the current collector, and a current collecting plate is attached to each of the positive non-current portion and the negative non-current portion, and by connecting the current collecting plate to an electrode terminal, it can function as an electrode tab.

[0168] According to one embodiment of the present invention, the battery can may be a cylindrical battery can for accommodating the electrode assembly and the electrolyte.

[0169] The above electrode assembly may be a jelly roll wound with an anode, a separator, and a cathode laminated together.

[0170] The form factor ratio of the cylindrical lithium secondary battery according to the present invention (defined as the value obtained by dividing the diameter of the cylindrical battery by the height, i.e., the ratio of the diameter (R) to the height (H)) is the same as described above, so a detailed explanation is omitted.

[0171] The cylindrical lithium secondary battery according to the present invention may be, for example, a 46110 cell (diameter 46 mm, height 110 mm, form factor ratio 0.418), a 4875 cell (diameter 48 mm, height 75 mm, form factor ratio 0.640), a 48110 cell (diameter 48 mm, height 110 mm, form factor ratio 0.436), a 4880 cell (diameter 48 mm, height 80 mm, form factor ratio 0.600), a 4680 cell (diameter 46 mm, height 80 mm, form factor ratio 0.575), or a 4695 cell (diameter 46 mm, height 95 mm, form factor ratio 0.484). In the figures representing the form factor, the first two digits represent the diameter (R) of the lithium secondary battery, and the next two or three digits represent the height (H) of the lithium secondary battery.

[0172] According to one embodiment of the present invention, the electrolyte comprises a lithium salt and an organic solvent.

[0173] The above lithium salt can be used without special limitations as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the above lithium salt may include one or more selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, preferably one or more selected from the group consisting of LiPF6. The concentration of the above lithium salt may be 1.0 to 1.5 M, preferably 1.0 to 1.4 M, more preferably 1.0 to 1.3 M, and even more preferably 1.15 to 1.3 M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and allow lithium ions to move effectively.

[0174] The above organic solvent may include one or more selected from the group consisting of cyclic carbonate-based organic solvents, linear carbonate-based organic solvents, linear ester-based organic solvents, and cyclic ester-based organic solvents.

[0175] The above-mentioned cyclic carbonate-based organic solvent is a high-viscosity organic solvent and may include at least one organic solvent selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, and vinylene carbonate.

[0176] In addition, the above-mentioned linear carbonate-based organic solvent is an organic solvent having low viscosity and low dielectric constant, and as a representative example, at least one organic solvent selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, ethylmethyl carbonate (EMC), methylpropyl carbonate, and ethylpropyl carbonate may be used, and specifically, it may include dimethyl carbonate (DMC) and ethylmethyl carbonate (EMC).

[0177] Specific examples of the above linear ester-based organic solvent may include at least one organic solvent selected from the group consisting of methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, and butyl propionate.

[0178] The above-mentioned cyclic ester-based organic solvent may include at least one organic solvent selected from the group consisting of γ-butyrolactone, γ-valerolactone, γ-caprolactone, σ-valerolactone, and ε-caprolactone.

[0179] Preferably, the electrolyte according to the present invention may include ethylene carbonate and dimethyl carbonate as organic solvents.

[0180] Meanwhile, in addition to the electrolyte components, the above electrolyte may additionally include other additives for the purpose of improving the lifespan characteristics of the battery, suppressing the reduction of battery capacity, and improving the discharge capacity of the battery.

[0181] These other additives may include at least one other additive selected from the group consisting of cyclic carbonate compounds, halogen-substituted carbonate compounds, sulfone compounds, sulfate compounds, borate compounds, nitrile compounds, benzene compounds, amine compounds, silane compounds, and lithium salt compounds different from the lithium salt contained in the electrolyte, as representative examples.

[0182] Specifically, the above other additives are vinylene carbonate (VC), vinylethylene carbonate, fluoroethylene carbonate (FEC), 1,3-propane sulfone (PS), 1,4-butane sulfone, ethene sulfone, 1,3-propene sulfone (PRS), 1,4-butene sulfone, 1-methyl-1,3-propene sulfone, ethylene sulfate (ESA), trimethylene sulfate (TMS), methyl trimethylene sulfate (MTMS), tetraphenyl borate, lithium oxalyl difluoroborate, succinonitrile, adiponitrile, acetonitrile, propionitrile, butyronitrile, valeronitrile, caprylonitrile, heptanitrile, cyclopentane carbonitrile, cyclohexane carbonitrile, Examples include one or more compounds selected from the group consisting of 2-fluorobenzonitrile, 4-fluorobenzonitrile, difluorobenzonitrile, trifluorobenzonitrile, phenylacetonitrile, 2-fluorophenylacetonitrile, 4-fluorophenylacetonitrile, fluorobenzene, triethanolamine, ethylenediamine, tetravinylsilane, LiN(SO2F)2 (Lithium bis(fluorosulfonyl)imide, LiFSI), LiN(SO2CF3)2 (lithium bis(trifluoromethane sulfonyl)imide, LiTFSI), LiPO2F2, LiODFB, LiBOB (lithium bis-oxalate toborate (LiB(C2O4)2)) and LiBF4.

[0183] The above other additives may be included in an amount of 0.01 to 20 weight% based on the total weight of the electrolyte, and preferably in an amount of 0.05 to 5.0 weight%. If the content of the above other additives is less than 0.01 weight%, the effect of improving low-temperature output, high-temperature storage characteristics, and high-temperature life characteristics of the battery is negligible, and if the content of the above other additives exceeds 20 weight%, there is a possibility that excessive side reactions may occur within the electrolyte during charging and discharging of the battery. In particular, when the above SEI film-forming additives are added in excess, they may not decompose sufficiently at high temperatures and may remain as unreacted substances or precipitated within the electrolyte at room temperature. Accordingly, side reactions that degrade the lifespan or resistance characteristics of the secondary battery may occur.

[0184] The present invention provides a battery module including a cylindrical lithium secondary battery and a battery pack including the same according to one embodiment of the present invention.

[0185] The cylindrical lithium secondary battery according to the present invention as described above can be used to manufacture a battery pack. The battery pack comprises an assembly of lithium secondary batteries electrically connected according to the present invention and a pack housing that accommodates the same, wherein the pack housing may include a busbar for electrically connecting the lithium secondary batteries, a cooling unit, an external terminal, etc. The battery pack may be mounted in a vehicle. The vehicle may be, for example, an electric vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehicle includes a four-wheeled vehicle or a two-wheeled vehicle. In particular, the lithium secondary battery according to the present invention has high energy density and excellent rapid charging performance, so it can be usefully used as a battery for an electric vehicle.

[0186] Although the present invention has been described above by limited embodiments and drawings, the present invention is not limited thereto, and it is obvious that various modifications and variations are possible within the scope of the technical spirit of the present invention and the equivalent scope of the claims described below by those skilled in the art to which the present invention belongs.

[0187]

[0188] Example 1

[0189] A cathode slurry was prepared by adding a cathode active material, a conductive material, and a binder to distilled water in a weight ratio of 98:0.2:1.8. At this time, graphite was used as the cathode active material, carbon nanotubes were used as the conductive material, and a cellulose-based binder was used as the binder.

[0190] The above cathode slurry was applied onto a copper current collector with a thickness of 8 μm, dried, and then subjected to roll pressing to manufacture a cathode including a cathode active material layer. At this time, the thickness of the cathode is 188 μm, and the loading amount of the cathode active material layer is 0.35 g / 25 cm 2 The porosity was 25.9%.

[0191] The thickness of the above-mentioned cathode and the porosity of the cathode active material layer are listed in Table 1.

[0192] A positive electrode slurry was prepared by adding a positive electrode active material, a conductive material, and a binder to N-methylpyrrolidone in a weight ratio of 98:0.5:1.5. At this time, lithium nickel-cobalt-manganese oxide was used as the positive electrode active material, carbon nanotubes as the conductive material, and PVDF as the binder.

[0193] The above anode slurry was applied onto an aluminum current collector, dried, and then rolled to manufacture an anode.

[0194] A jelly roll type electrode assembly was manufactured by interposing a separator between the anode and cathode prepared as described above, stacking them in the order of separator / anode / separator / cathode, and then winding them.

[0195] An electrolyte was prepared by adding LiPF6 at a molar concentration of 1.25 M to an organic solvent mixed with ethylene carbonate (EC), dimethyl carbonate (DMC), and ethylmethyl carbonate (EMC) in a weight ratio of 2:7:1. The injection fraction of the electrolyte was 0.98, and the injection volume was 32 g.

[0196] As mentioned above, the total internal volume of the electrode assembly is 122.93 cm³ 3 After inserting it into a cylindrical battery case, 25.7 mL of the electrolyte prepared above was injected to manufacture 4680 cells. At this time, the void volume (V) of the manufactured lithium secondary battery p ) is 26cm 3 It was measured as.

[0197] In the above Equation 1, the diameter (R) of the cylindrical lithium secondary battery and the height (h) of the cylindrical lithium secondary battery are measured through the external appearance of the cell, the thickness (Ta) of the negative electrode is measured by a micrometer, the porosity is calculated by Equation 1-1 through the thickness of the electrode and the loading amount, and the injection fraction is calculated by Equation 2.

[0198]

[0199] Example 2

[0200] A cathode and a lithium secondary battery were manufactured in the same manner as in Example 1 above, except that the thickness of the cathode was 187 μm, the porosity was 25.6%, the electrolyte injection fraction was 1.0, and the injection amount was 32.5 g.

[0201]

[0202] Example 3

[0203] A negative electrode and a lithium secondary battery were manufactured in the same manner as in Example 2 above, except that the electrolyte injection fraction was 1.03 and the injection amount was 33.5g.

[0204]

[0205] Example 4

[0206] A negative electrode and a lithium secondary battery were manufactured in the same manner as in Example 1 above, except that the electrolyte injection fraction was 1.04 and the injection amount was 34g.

[0207]

[0208] Example 5

[0209] The thickness of the cathode is 170㎛, and the loading amount of the cathode active material layer is 0.33g / 25cm 2 A negative electrode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the porosity of the negative electrode active material layer was 26.0%, the injection fraction of the electrolyte was 1.0, and the injection amount was 33.5g.

[0210]

[0211] Comparative Example 1

[0212] A cathode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the thickness of the cathode is 184 μm, the porosity of the cathode active material layer is 23.9%, and the injection fraction of the electrolyte is 1.03.

[0213]

[0214] Comparative Example 2

[0215] A negative electrode and a lithium secondary battery were manufactured in the same manner as in Example 4 above, except that the electrolyte injection fraction was 1.1 and the injection amount was 36g.

[0216]

[0217] Comparative Example 3

[0218] A negative electrode and a lithium secondary battery were manufactured in the same manner as in Example 3 above, except that the electrolyte injection fraction was 1.11 and the injection amount was 36g.

[0219]

[0220] Comparative Example 4

[0221] A cathode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the thickness of the cathode is 188 μm, the porosity of the cathode active material layer is 25.0%, the injection fraction of the electrolyte is 1.12, and the injection amount is 36 g.

[0222]

[0223] Comparative Example 5

[0224] A cathode and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the thickness of the cathode is 176 μm, the porosity of the cathode active material layer is 24.4%, the injection fraction of the electrolyte is 1.21, and the injection amount is 38 g.

[0225]

[0226] The characteristics of the lithium secondary batteries prepared in Examples 1 to 5 and Comparative Examples 1 to 5 and the F value represented by Formula 1 below are shown in Table 1 below.

[0227]

[0228] R (mm)h (mm)f injection T a (㎛)P a (%) Energy retention (%) Example 1 46800 0.9818825.912.493.5 Example 2 46801.018725.612.794.2 Example 3 46801.0318725.613.193.4 Example 4 46801.0418825.913.194.1 Example 5 46801.017026.011.495 .0 Comparative Example 1 46801.0318423.913.891.7 Comparative Example 2 46801.118825.913.986.1 Comparative Example 3 46801.1118725.614.184.4 Comparative Example 4 46801.121882514.680.0 Comparative Example 5 46801.2117624.415.270.0

[0229]

[0230] Experimental Example 1: Evaluation of whether lithium plating occurs during rapid charging

[0231] Each cell prepared in the above examples and comparative examples was charged in CC / CV mode at 40°C with a constant current (CC) of 1.0C until it reached 4.2V (cut-off current 0.05C), and then discharged in CC mode with a constant current (CC) of 1.0C until it reached 2.5V. The above charging and discharging process was defined as one cycle, and after repeating the charging and discharging up to 100 cycles, the 4680 cells were disassembled and the electrode assembly separated to visually check for the occurrence of lithium plating on the surface of the negative electrode. The results are shown in Table 2 below.

[0232] - O: Lithium plating occurred.

[0233] - X: No lithium plating occurs.

[0234]

[0235] Whether lithium plating occurs Example 1X Example 2X Example 3X Example 4X Example 5X Comparative Example 1O Comparative Example 2O Comparative Example 3O Comparative Example 4O Comparative Example 5O

[0236]

[0237] Experimental Example 2: Rapid Charge Life Characteristics

[0238] Each cell manufactured in the above examples and comparative examples was charged in CC / CV mode at 40°C with a constant current (CC) of 1.0C until it reached 4.2V (cut-off current 0.05C), and then discharged in CC mode with a constant current (CC) of 1.0C until it reached 2.5V. The above charging and discharging process was defined as one cycle, and after repeating the charging and discharging up to 100 cycles, the capacity retention rate was measured and recorded in Table 1 and Figure 1.

[0239] According to Table 1 above, the characteristics of the cylindrical lithium secondary battery manufactured according to Examples 1 to 5, such as the diameter (R) and height (h) of the cylindrical lithium secondary battery, the porosity of the negative electrode active material layer, the thickness of the negative electrode, and the injection fraction of the electrolyte, satisfy the F value of Equation 1 of 13.5 or less, and thus it was possible to predict and confirm that the rapid charging performance of the cylindrical lithium secondary battery is excellent.

[0240] In addition, the cylindrical lithium secondary battery showed a capacity retention rate (%) of 92% or more after 100 cycles of charging and discharging at 40°C at a 1C-rate, confirming that the rapid charging performance of the cylindrical lithium secondary battery is excellent.

[0241] It was found that even if the electrolyte is displaced as the cathode expands due to high current density during rapid charging, controlling the electrolyte injection amount minimizes the amount of electrolyte pushed out of the electrode, thereby improving side reactions such as lithium deposition on the electrode surface and enhancing rapid charging life characteristics.

[0242] On the other hand, it was predicted and confirmed that the rapid charging performance of the cylindrical lithium secondary battery was not improved, as the characteristics of the cylindrical lithium secondary battery manufactured according to Comparative Examples 1 to 5, such as the diameter (R) and height (h) of the cylindrical lithium secondary battery, the porosity of the negative electrode active material layer, the thickness of the negative electrode, and the injection fraction of the electrolyte, did not satisfy the condition that the F value of Equation 1 is 13.5 or less.

[0243] In particular, the injection fraction in F of Equation 1 above can be controlled by the amount of electrolyte injection, and since the injection fraction increases as the amount of injection increases and decreases as the amount of injection decreases under conditions where other factors such as the void volume are fixed, the injection fraction can be controlled by controlling the amount of electrolyte injection in Comparative Examples 1 to 5 compared to Examples 1 to 5.

[0244] In addition, the capacity retention rate (%) of the cylindrical lithium secondary battery was less than 92% after 100 cycles of charging and discharging at 40°C at a 1C-rate, confirming that the rapid charging performance of the cylindrical lithium secondary battery was inferior to that of the example, and that side reactions such as lithium precipitation occurred on the electrode surface.

[0245] In addition, in the case of Comparative Examples 1 to 6, it was confirmed that the rapid charging performance tended to be inferior as the value of F in Equation 1 increased.

[0246] Therefore, it was found that when the value of F in Equation 1 satisfies 13.5 or less, lithium ions can be inserted into the interior of the negative electrode active material layer, thereby improving side reactions such as lithium precipitation on the electrode surface and enhancing rapid charging life characteristics, and it was confirmed that by controlling F in Equation 1, lithium precipitation and rapid charging life characteristics can be predicted and improved.

Claims

1. A method for predicting the rapid charging performance of a cylindrical lithium secondary battery comprising a positive electrode, a separator, a negative electrode, and an electrolyte, wherein The above cathode comprises a cathode current collector; and a cathode active material layer provided on at least one surface of the cathode current collector, and The diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and the porosity P of the negative electrode active material layer. a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte. injection A method for predicting the rapid charging performance of a cylindrical lithium secondary battery, comprising the step of verifying the rapid charging performance of the cylindrical lithium secondary battery using 2. In Claim 1, The step of verifying the rapid charging performance of the above-mentioned cylindrical lithium secondary battery is the thickness T of the above-mentioned negative electrode. a and f, which is the injection fraction of the above electrolyte injection P, which is the porosity of the above-mentioned cathode active material layer for . a A method for predicting the rapid charging performance of a cylindrical lithium secondary battery using the ratio of 3. In Claim 1, The step of verifying the rapid charging performance of the above-mentioned cylindrical lithium secondary battery involves the diameter (R) of the above-mentioned cylindrical lithium secondary battery, the height (h) of the above-mentioned cylindrical lithium secondary battery, and P, which is the porosity of the negative electrode active material layer. a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte. injection A method for predicting the rapid charging performance of a cylindrical lithium secondary battery, comprising the step of checking whether the F value of the following Equation 1, which includes , satisfies 13.5 or less. [Equation 1] 4. In Claim 1, The above separator comprises a porous substrate and a porous coating layer provided on at least one surface of the porous substrate, and f, the fraction of the above electrolyte injection solution injection is calculated from the following Equation 2 or Equation 3, and f, the fraction of the above electrolyte injection solution injection A method for predicting the rapid charging performance of a cylindrical lithium secondary battery, comprising a step of checking whether it is 0.95 or higher and 1.05 or lower: [Equation 2] [Equation 3] In the above Equation 2 or Equation 3, The above V a is the void volume of the negative electrode active material layer, and V c is the void volume of the positive active material layer, and V s is the pore volume of the separator, V srs is the pore volume of the porous coating layer, and V electrolyte is the volume of the electrolyte, and The above delectrolyte is the density of the electrolyte, and the above M electrolyte is the mass of the electrolyte, and The above l a is the length of the negative electrode active material layer, the above l c is the length of the positive active material layer, the above l s is the length of the separator, and the above l srs is the length of the porous coating layer, and The above w a is the width of the negative electrode active material layer, and the above w c is the width of the positive active material layer, and the above w s is the width of the separator, and the above w srs is the width of the porous coating layer, and The above t a is the thickness of the negative electrode active material layer, and the above t c is the thickness of the positive active material layer, and the above t s is the thickness of the separator, and the above t srs is the thickness of the porous coating layer, and The above p a is the porosity of the negative electrode active material layer, and the above p c is the porosity of the positive active material layer, the above p s is the porosity of the separation membrane, and the above p srs is the porosity of the porous coating layer.

5. In Claim 3, A method for predicting the rapid charging performance of a cylindrical lithium secondary battery, wherein the value of F in Equation 1 above satisfies 10 or more and 13.3 or less.

6. In Claim 1, The above T a A method for predicting the rapid charging performance of a cylindrical lithium secondary battery, wherein (㎛) is determined to satisfy 170㎛ or more and 188㎛ or less.

7. In Claim 1, The above P a A method for predicting the rapid charging performance of a cylindrical lithium secondary battery, wherein (%) is a method for verifying whether it satisfies 23% or more and 26% or less.

8. In Claim 3, A method for predicting the rapid charging performance of a cylindrical lithium secondary battery, wherein the cylindrical lithium secondary battery satisfying the F value of Equation 1 above being 13.5 or less has a capacity retention rate (%) of 92% or more after 100 cycles of charging and discharging at 40℃ at a 1C-rate.

9. A cylindrical lithium secondary battery comprising a positive electrode, a separator, a negative electrode, and an electrolyte, The above cathode comprises a cathode current collector; and a cathode active material layer provided on at least one surface of the cathode current collector, and The diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and the porosity P of the negative electrode active material layer. a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte. injection A cylindrical lithium secondary battery satisfying that the F value of the following Formula 1 containing is 13.5 or less. [Equation 1] 10. In Claim 9, The above separator comprises a porous substrate and a porous coating layer provided on at least one surface of the porous substrate, and The fraction of the above electrolyte injection solution (f injection ) is calculated from the following Equation 2 or Equation 3, and f, the fraction of the above electrolyte injection solution injection Cylindrical lithium secondary battery with a value of 0.95 or higher and 1.05 or lower: [Equation 2] [Equation 3] In the above Equation 2 or Equation 3, The above V a is the void volume of the negative electrode active material layer, and V c is the void volume of the positive active material layer, and V s is the pore volume of the separator, V srs is the pore volume of the porous coating layer, and V electrolyte is the volume of the electrolyte, and The above delectrolyte is the density of the electrolyte, and the above M electrolyte is the mass of the electrolyte, and The above l a is the length of the negative electrode active material layer, the above l c is the length of the positive active material layer, the above l s is the length of the separator, and the above l srs is the length of the porous coating layer, and The above w a is the width of the negative electrode active material layer, and the above w c is the width of the positive active material layer, and the above w s is the width of the separator, and the above w srs is the width of the porous coating layer, and The above t a is the thickness of the negative electrode active material layer, and the above t c is the thickness of the positive active material layer, and the above t s is the thickness of the separator, and the above t srs is the thickness of the porous coating layer, and The above p a is the porosity of the negative electrode active material layer, and the above p c is the porosity of the positive active material layer, the above p s is the porosity of the separation membrane, and the above p srs is the porosity of the porous coating layer.

11. In Claim 9, A cylindrical lithium secondary battery in which the F value of Equation 1 above is 10 or more and 13.3 or less.

12. In Claim 9, The above T a (㎛) is a cylindrical lithium secondary battery with a size of 170 ㎛ or more and 188 ㎛ or less.

13. In Claim 9, The above P a A cylindrical lithium secondary battery in which (%) is 23% or more and 26% or less.

14. In Claim 9, The above cylindrical lithium secondary battery is a cylindrical lithium secondary battery having a capacity retention rate (%) of 92% or more after 100 cycles of charge and discharge at 40°C at a 1C-rate.

15. A battery module comprising a cylindrical lithium secondary battery according to any one of claims 9 to 14.

16. A battery pack comprising a cylindrical lithium secondary battery according to any one of claims 9 to 14.

17. A battery pack comprising a battery module according to claim 15.

18. A step of manufacturing a jelly roll wound with an anode, a separator, and a cathode laminated; and The method comprises the step of manufacturing a cylindrical lithium secondary battery that includes housing the above-mentioned jelly roll in a battery can, providing an electrolyte, and including a sealing body that seals the above-mentioned battery can. The above cathode comprises a cathode current collector; and a cathode active material layer provided on at least one surface of the cathode current collector, and The diameter (R) of the cylindrical lithium secondary battery, the height (h) of the cylindrical lithium secondary battery, and the porosity P of the negative electrode active material layer. a , the thickness T of the above cathode a , and f, which is the injection fraction of the above electrolyte. injection A method for manufacturing a cylindrical lithium secondary battery according to any one of claims 7 to 12, comprising the step of designing such that the F value of the following formula 1, including , satisfies 13.5 or less. [Equation 1]

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