Secondary battery

Abstract

Having a secondary battery: an electrode arrangement; an electrolyte; a battery casing that houses the electrode assembly and the electrolyte, where the secondary battery is configured to satisfy the following equation 1: W / S ≤ 42 (g / Ah) ⋅ m − 2 where in equation 1 W is a weight of the electrolyte in g per unit capacity of the secondary battery in Ah and S is a product of a length in m and a width in m of the electrode arrangement.

Description

Cross-reference to related registrations

[0001] This application claims priority over Korean patent application No. 10-2022-0132745, which was filed with the Korean Intellectual Property Office on October 14, 2022. BACKGROUND OF THE INVENTIONAL TECHNOLOGY FIELD

[0002] The present invention relates to a secondary battery. STATE OF THE ART

[0003] Compared to a can-type secondary battery, a pouch-type secondary battery can provide a higher energy density in terms of volume and / or weight. However, it may be desirable to increase mechanical strength, particularly with regard to resistance to external shocks and stresses. More generally, it may be desirable to increase the safety of a pouch-type secondary battery.

[0004] With the increasing diversification of secondary battery applications, it is desirable to improve the durability and safety of secondary batteries, particularly for use in harsh environments. In particular, it is desirable to increase the shock resistance of pouch-shaped secondary batteries. SUMMARY OF THE INVENTION

[0005] The technical problems known from the prior art are solved by the present invention, as defined by the features of the independent claims. Certain examples of the present invention are given by the features of the dependent claims. In particular, the present invention can contribute to increasing the frictional force between the electrode arrangement and a battery casing (e.g., a pouch), thereby suppressing displacement of the electrode arrangement and / or leakage of the electrolyte from the battery casing, even when subjected to an external shock or mechanical stress. Specifically, the present invention can solve the technical problem by a specific configuration of the size of an electrode arrangement and the number of electrodes per capacity.

[0006] A secondary battery can be provided. The secondary battery can comprise an electrode assembly, an electrolyte, and a battery casing that accommodates the electrode assembly and the electrolyte. The secondary battery can satisfy the following equation 1: W / S≤42(g / Ah)⋅m−2

[0007] In equation 1, W is the weight of the electrolyte in g (grams) per unit capacity of the secondary battery in Ah, and S is the product of a length in m (meters) and a width in m (meters) of the electrode arrangement.

[0008] The secondary battery, as disclosed herein, may additionally have any, some, or all of the features described below. It is considered that the secondary battery may be provided as a pouch-shaped battery, a cylindrical battery, or a prismatic battery. In specific examples, the secondary battery may be provided as a pouch-shaped battery.

[0009] Unless otherwise specified, the capacity of the secondary battery can be defined by a nominal capacity. The secondary battery can have a nominal capacity of 50 Ah to 200 Ah, preferably 50 Ah to 150 Ah, and more preferably 60 Ah to 140 Ah. The term "nominal capacity of a secondary battery" means the electrical capacity produced when a fully charged battery is continuously discharged at 0.33 C to a discharge end voltage. The full charge voltage (charge end voltage) and discharge end voltage can be suitably selected depending on the type of secondary battery. For example, if the secondary battery is an NCM cell, the nominal capacity can be the discharge capacity when the secondary battery is charged to 4.25 V and then discharged to 2.5 V at 0.33 C. The term "unit capacity" means 1 Ah. The parameter W can have the unit g / Ah (grams per ampere-hour).The parameter S can have the unit m. 2 (square meters). The quotient W / S can have the unit (g / Ah)·m². -2 exhibit. The parameter S can be 0.01 m 2 up to 0.2 m 2 or 0.02 m 2 up to 0.09 m 2 , preferably 0.03 m 2 up to 0.08 m 2 , preferably 0.03 m 2 up to 0.75 m 2 be.

[0010] Here, the weight of the electrolyte in the secondary battery refers to the amount of electrolyte remaining in the secondary battery after an activation process. Thus, the weight of the electrolyte can indicate the weight of the electrolyte present in the secondary battery after production is complete or during operation. For simplicity, the weight of the electrolyte can be used interchangeably with the (total) quantity of electrolyte.

[0011] The quotient W / S can be 0.1 (g / Ah)·m -2 up to 42 (g / Ah)·m -2, 1 (g / Ah)·m -2 up to 42 (g / Ah)·m -2 , 5 (g / Ah)·m -2 up to 42 (g / Ah)·m -2 , 10 (g / Ah)·m -2 up to 42 (g / Ah)·m -2 or 20 (g / Ah)·m -2 up to 42 (g / Ah)·m -2 to be, without being limited to. In a specific example, the quotient W / S can be 30 (g / Ah)·m -2 up to 42 (g / Ah)·m -2 be.

[0012] The electrolyte can be present on the surfaces of the electrode assembly and on an inner surface of the battery casing. The electrolyte may have a non-zero viscosity and specific wetting properties, and thus its presence in the battery casing can reduce friction between the electrode assembly and the inner surface of the casing. In particular, increasing the electrolyte density in the secondary battery can continuously reduce friction between the electrode assembly and the inner surface of the battery casing. Furthermore, the friction between the electrode assembly and the inner surface of the battery casing can also depend on a friction surface area, which can be defined by the product S of the length and width of the electrode assembly.

[0013] On the other hand, a reduction in electrolyte can adversely affect the capacity of the secondary battery and even impair its functionality and lifespan. Against this background, the inventors of the present application sought to find a parameter range in which a balance is achieved between high capacity, a suitable amount of electrolyte, and the size of the electrode assembly. The subject matter of the independent claims reflects such a parameter range (or ranges). In this way, high friction between the electrode assembly and the inner surface of the battery casing is ensured, thereby suppressing displacement of the electrode assembly within or out of the battery casing, while maintaining a suitable amount of electrolyte in the secondary battery.

[0014] A secondary battery can be manufactured by preparing a slurry of electrode active material and applying it to a positive electrode collector and a negative electrode collector, thus obtaining a positive electrode and a negative electrode. One or more layers of the positive electrode and one or more layers of a separator are stacked such that the separator is positioned between a layer of the positive electrode and a layer of the negative electrode, thus obtaining an electrode assembly. The electrode assembly is housed in a battery casing, which may be a pouch, a cylindrical can, or a polyhedral can, and an electrolyte is introduced into the battery casing.

[0015] A pouch-type secondary battery can be manufactured by pressing a pouch film stack to form a well section specifically configured (e.g., shaped and dimensioned) to accommodate the electrode assembly. After the electrode assembly is positioned within the well section, an electrolyte can be added, and the pouch film stack can be tightly sealed along a sealing section. A can-type secondary battery can be manufactured by enclosing an electrode assembly in a can made of a metal material, introducing an electrolyte into the can, and sealing the can by attaching a cap to one of its openings. As mentioned, the can can have a cylindrical or polyhedral shape, such as a (rectangular) cuboid or a rhombus.

[0016] The electrolyte of the secondary battery can be provided as described in detail below. The electrode arrangement of the secondary battery can be provided as described in detail below. The battery housing of the secondary battery can be a pouch, which may be used according to the understanding in the field of design and manufacture of secondary batteries. Alternatively, the battery housing of the secondary battery can be a can as described herein. In particular, the electrolyte can be provided, at least partially, between the electrode arrangement and an inner surface of the battery housing facing the electrode arrangement.

[0017] In particular, in a pouch-shaped secondary battery, the electrode arrangement may have a rectangular shape in a plan view, elongated in a longitudinal direction, which may herein be referred to as a longitudinal direction. The length, as used herein, may be measured in the longitudinal direction unless otherwise specified. A transverse direction of the electrode arrangement specifies a direction perpendicular to the longitudinal direction and lying in the plane of at least one of the positive electrode layer(s), the negative electrode layer(s), and the separator(s). The width, as used herein, may be measured in the transverse direction unless otherwise specified. In the electrode arrangement, the positive electrode layer(s), the negative electrode layer(s), and the separator(s) may be stacked in a thickness direction perpendicular to both the longitudinal and transverse directions.In this context, the top view can refer to a viewing direction parallel to the thickness direction of the electrode arrangement.

[0018] In the case of a can-shaped secondary battery, the electrode arrangement, as described above, can be wound along a winding axis parallel to either the longitudinal or the lateral direction. Accordingly, the other direction of the longitudinal and lateral directions that is not parallel to the winding axis can be parallel to a circumferential direction of the electrode arrangement. In the case of a can-shaped secondary battery, the length can refer to the length in the direction of the winding axis in the wound state, and the width can refer to the length in the direction perpendicular to the winding axis in the wound state.

[0019] The battery casing can be a pouch, which can be provided in any manner disclosed herein. In particular, the pouch can be formed by pressing at least one basin section into a pouch film layer. Thus, the basin section can be formed as a flat section projecting outwards from the rest of the pouch film layer. The basin section can have a basin-like shape. The basin section can have a flat main surface surrounded by one or more side walls that are integral with the rest of the pouch film layer. The flat main surface of the basin section can have a rectangular basic shape in plan view, whereby the corners can be rounded due to processing requirements or by design. The pouch can implement any, some, or all of the features of the pouch as disclosed herein, unless otherwise specified or technically impractical.

[0020] In a specific example, the battery casing can be a pouch made from a pouch film layer. The pouch, and in particular the pouch film layer, can have a barrier layer, a base material layer, and a sealing layer. The base material layer can be arranged on one surface of the barrier layer, and the sealing layer can be arranged on the other surface of the barrier layer (i.e., opposite the base material layer). In some examples, the base material layer, the barrier layer, and the sealing layer can form the pouch film layer, in particular a laminate structure. The pouch, and in particular the pouch film layer thereof, can be compression-molded (in particular stretch-molded and / or drawn) so that it has one or more trough sections that protrude outwards (from the rest of the pouch or the rest of the pouch film layer).The electrode array can be accommodated in one or more pouch sections. The one or more pouch sections can be shaped and dimensioned to accommodate the electrode array. Each pouch component can implement any one, some, or all of the respective features disclosed herein, unless otherwise specified or technically impractical. In particular, any of the base material layer, barrier layer, and sealing layer can be implemented, as each is described in detail below.

[0021] The secondary battery can have a nominal capacity of 50 Ah to 200 Ah, preferably 50 Ah to 150 Ah and more, preferably 60 Ah to 140 Ah.

[0022] The electrode arrangement can have a substantially rectangular shape in plan view, such that the length-to-width ratio of the electrode arrangement is in the range of 2.5 to 20, or 3 to 15, or 5 to 10. The specific aspect ratio of the electrode arrangement can further contribute to increasing the aforementioned friction without increasing the electrolyte requirement.

[0023] The electrode arrangement can have a length of 200 mm to 800 mm and a width of 40 mm to 200 mm. The electrode arrangement can have a length of 400 mm to 600 mm and a width of 50 mm to 150 mm. Preferably, the electrode arrangement can have a length of 500 mm to 600 mm and a width of 50 mm to 100 mm. The specific combination of the length and width of the electrode arrangement can further contribute to increasing friction as discussed above without increasing the electrolyte requirement. The length and width can each refer to a maximum extent of the electrode arrangement in the longitudinal direction and the lateral direction, respectively, in a top view. To emphasize this aspect, the term "length" may be used interchangeably herein with "full length." For a similar reason, the term "width" may be used interchangeably herein with "full width."

[0024] Furthermore, the weight of the electrode assembly can range from 500 g to 1500 g, preferably from 550 g to 1450 g, and even more preferably from 600 g to 1400 g. If the weight of the electrode assembly falls within the above range, a high capacity can be achieved, and the friction between the electrode assembly and the inner surface of the battery casing increases, resulting in excellent shock resistance.

[0025] Furthermore, the secondary battery may also have at least one fastening element attached to the outer surface of the electrode assembly by winding the electrode assembly in the width direction. In this case, the contact area between the fastening element and the electrode assembly may be 30% or less, 0 to 30%, 1 to 30%, 5 to 30%, 5 to 25%, or 5 to 20% of the total surface area of ​​the electrode assembly. Since the fastening element is generally made of a material with a low coefficient of friction, the friction between the electrode assembly and the inner surface of the battery casing may decrease as the area of ​​the fastening element increases. Therefore, when using a fastening element, it is desirable to suppress any decrease in frictional force by setting the contact area between electrode assemblies to 30% or less.

[0026] A frictional force between the electrode assembly and an inner surface of the battery casing can be 15 kgf or more, preferably 15 kgf to 40 kgf, more preferably 17 kgf to 35 kgf. A section of the battery casing was opened by cutting; the positive electrode tab of the electrode assembly was held with a clamping device connected to a wire; the wire was connected to a universal testing machine (UTM); a force applied while the wire was pulled at 100 mm / min was measured to determine the frictional force between the electrode assembly and the inner surface of the battery casing.

[0027] If a crash shock test is performed on the secondary battery under a crash condition of 133.7 G × 15.8 m / s, electrolyte leakage may be zero. The crash shock test was performed under a crash condition of 133.7 G × 15.8 m / s. After the crash shock test, the battery casing is examined for any weight loss of electrolyte due to leakage from the battery casing and for any displacement of the electrode assembly within or out of the battery casing.

[0028] In specific examples, the electrode array can have a length of 0.2 m to 0.8 m, a width of 0.05 m to 0.15 m, and an electrolyte weight per unit capacity of 1.0 to 2.8 g / Ah. Such examples can have a W / S ratio of 30 (g / Ah)·m². -2 up to 42 (g / Ah)·m -2 to reach.

[0029] In further specific examples, the electrode arrangement can have a length of 0.3 m to 0.8 m, a width of 0.06 m to 0.12 m, and an electrolyte weight per unit capacity of 1.2 to 2.5 g / Ah. Such examples can have a W / S ratio of 30 (g / Ah)·m². -2 up to 42 (g / Ah)·m -2 to reach.

[0030] In further specific examples, the electrode arrangement can have a length of 0.4 m to 0.6 m, a width of 0.07 m to 0.11 m, and an electrolyte weight per unit capacity of 1.5 to 2.4 g / Ah. Such examples can have a W / S ratio of 30 (g / Ah)·m². -2 up to 42 (g / Ah)·m -2 to reach.

[0031] According to another aspect, a secondary battery can be provided comprising an electrode assembly, an electrolyte, and a battery casing. The electrode assembly can have a surface area of ​​0.01 to 0.2 m². The electrolyte can be provided with a weight of 440 g or less. The battery casing can accommodate the electrode assembly and the electrolyte. The electrode assembly, the electrolyte, and the battery casing can be configured such that the frictional force between the electrode assembly and an internal surface of the battery casing is 15 kgf or more.

[0032] In particular, the surface area of ​​the electrode arrangement can be the product of its length and width, provided that the electrode arrangement has a rectangular shape as described above. The surface area of ​​the electrode arrangement can be 0.02 m² to 0.08 m², 0.03 m² to 0.07 m², or 0.04 m² to 0.06 m².

[0033] As mentioned above, the weight of the electrolyte indicates the weight of the electrolyte present in the secondary battery. For simplicity, the weight of the electrolyte can be used interchangeably here with the (total) quantity of electrolyte.

[0034] Additionally, the secondary battery of this aspect can implement any, some, or all of the features of the secondary battery and its components as disclosed herein. A repetition of all features is omitted for brevity and readability. Furthermore, as described above, the secondary battery can implement any, some, or all of the features described in relation to the secondary battery of the latter aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and other aspects, features and other advantages will become clearer from the following detailed description in conjunction with the attached drawings. Fig. Figure 1 is a perspective exploded view of a secondary battery according to an example. Fig. 2 is a view to explain a pouch configuration. DETAILED DESCRIPTION OF THE PREFERRED EXECUTION FORM

[0036] Terms or words used in the description and claims should not be interpreted as having a limited lexical meaning and should be understood as appropriate terms by the inventor, based on his / her ability to define terms to describe his / her invention in the best way to be recognized by others.

[0037] As demand for high-capacity batteries, particularly for electric vehicles, has increased, so too has the nominal capacity of each secondary battery cell. This has led to a trend toward increasing the size and weight of a secondary battery's electrode assembly. However, as the size and weight of the electrode assembly have increased, the battery casing has become more susceptible to damage from external impacts, and the electrode assembly is more likely to shift within the casing or even be ejected. Such adverse situations are more critical for pouch batteries, which have relatively low casing rigidity. If the casing is damaged, electrolyte can leak, or the electrode assembly can deform, seriously compromising battery performance and safety.

[0038] As a result of repeated investigations aimed at solving problems known from the prior art, where the dimensions of the electrode assembly and the electrolyte content meet specific conditions with regard to capacity, it was found that the frictional force between the electrode assembly and the battery casing can be increased. This can suppress displacement of the electrode assembly and / or leakage of the electrolyte from the battery casing, even when subjected to an external shock, thereby increasing shock resistance.

[0039] A secondary battery may comprise: a battery casing having an electrode assembly and a receiving part for receiving an electrolyte; and the electrode assembly and electrolyte received in the receiving part satisfying Equation 1 below. W / S≤42

[0040] Where the quotient W / S in equation 1 has a dimension of (g / Ah)·m -2 can exhibit.

[0041] The parameter W can be the weight of the electrolyte per unit capacity (i.e., per 1 Ah) of the secondary battery and can be measured by dividing the amount of electrolyte (unit: g) in the secondary battery by the nominal capacity (unit: Ah) of the secondary battery. The weight of the electrolyte can be given in grams (g). The capacity can be defined as the nominal capacity of the secondary battery and can be given in ampere-hours (Ah). The weight (amount) of electrolyte in the secondary battery can refer to the weight (amount) of electrolyte remaining in the secondary battery after an activation process.

[0042] The W / S ratio can preferably be approximately 30 (g / Ah)·m² -2 up to approximately 42 (g / Ah)·m -2 , preferably about 35 (g / Ah)·m -2 up to approximately 42 (g / Ah)·m-2 The value is approximately 42 (g / Ah)·m³. -2 If the value is less than or greater, a frictional force between the electrode assembly and an inner surface of the battery casing (e.g., a lower surface of a basin section) that is in contact with the electrode assembly can increase significantly, and consequently, if an external shock is received, displacement of the electrode assembly can be suppressed, thus preventing leakage of the electrolyte from the battery casing.

[0043] The parameter W can vary depending on the size of the electrode arrangement, but can be, for example, approximately 2.2 g / Ah or less, preferably approximately 1.5 g / Ah to approximately 2.2 g / Ah, and preferably approximately 1.7 g / Ah to approximately 2.2 g / Ah. If W is too large, the effect of increasing the frictional force between the electrode arrangement and the inner surface of the battery casing may be negligible. If W is too small, battery performance may be impaired due to a lack of electrolyte.

[0044] The parameter S can specify the area of ​​the electrode array in plan view, as described above. S can also be a value obtained by multiplying the length and width of the electrode array. The length and width can be specified in meters (m).

[0045] S can be approximately 0.02 m, for example. 2 up to about 0.09 m 2 , preferably about 0.03 m 2up to about 0.08 m 2 and preferably about 0.03 m 2 up to about 0.75 m 2 The value of S must be appropriate. If S is too small, the battery capacity may decrease, and the effect of increasing the frictional force between the electrode assembly and the battery casing may become negligible. If S is too large, the risk of damage and even fire due to instability problems may increase.

[0046] The secondary battery can have a nominal capacity of approximately 50 Ah to approximately 200 Ah, preferably approximately 50 Ah to approximately 150 Ah, and preferably approximately 60 Ah to approximately 140 Ah. If the nominal capacity of the secondary battery falls within the above range, a high-capacity secondary battery can be implemented.

[0047] The secondary battery can be a pouch-shaped secondary battery. In this case, the battery casing can be a pouch that, for example, has a barrier layer, a base material layer arranged on one surface of the barrier layer, and a sealing layer arranged on the other surface of the barrier layer, and also has at least one or more well sections that are recessed in one direction, and the electrode arrangement and the electrolyte can be contained in the well section of the pouch.

[0048] If the conditions of equation (1) are met, the frictional force between the electrode arrangement and the lower surface of the pouch tray can be greater than about 15 kgf, preferably about 15 kgf to about 40 kgf, more preferably about 17 kgf to about 35 kgf, in order to minimize the separation of the electrode arrangement due to the external impact, thereby minimizing damage to the pouch and thus increasing the impact resistance.

[0049] Here, the frictional force between the electrode arrangement and the lower surface of the pouch tray can be measured using the following method.

[0050] First, a section of the secondary battery pouch can be opened by cutting, a positive electrode tab can be held with a clamping device connected to a wire, the wire can be connected to a universal testing machine (UTM), and then the force exerted while the wire is pulled at a speed of about 100 mm / min can be measured to assess the frictional force between the electrode assembly and the lower surface of the tub section.

[0051] The secondary battery according to the present invention can exhibit a high frictional force between the electrode assembly and the battery housing in order to minimize the detachment of the electrode assembly when an external impact is applied, thereby demonstrating excellent shock resistance. For example, in the secondary battery according to the present invention, when a crash shock test is performed under a crash condition of approximately 133.7 G × 15.8 ms, electrolyte leakage cannot occur.

[0052] The crash shock test can be performed by attaching the battery under test to a clamping device of a drop test rig, and then allowing the battery to fall freely to a specific height to determine if it is damaged. Here, the free fall height is set according to the crash condition being measured (acceleration × duration). Specifically, the free fall height can be set by converting the impact energy under the crash condition being measured into potential energy, and then calculating a height at which the converted potential energy is obtained, taking into account the weight of the battery under test. Whether the battery is damaged can be assessed by the presence or absence of electrolyte leakage.

[0053] Fig. Figure 1 is a perspective exploded view of a secondary battery. Fig.Figure 2 shows a cross-sectional view of a pouch film layer. The secondary battery is described in more detail below. Pouch

[0054] The Pouch 100 can be a battery housing for receiving an electrode arrangement and an electrolyte and can have a barrier layer 20, a base material layer 10 arranged on one surface of the barrier layer, and a sealing layer 30 arranged on the other surface of the barrier layer, and can also have at least one or more basin sections (receiving part) that are recessed in one direction.

[0055] Specifically, the Pouch 100 can exhibit flexibility and can be manufactured by a process in which a pouch film layer, in which the base material layer 10, the barrier layer 20 and the sealing layer 30 are sequentially stacked, is placed in a compression molding device and pressure is applied to a portion of the pouch film layer using a punch, so that the pouch film layer is stretched to form a trough section that is recessed in one direction. Base material layer

[0056] The base material layer 10 can be placed on the outermost layer of the pouch and configured to protect the electrode assembly from external shock and to electrically insulate the electrode assembly.

[0057] The base material layer 10 can be made of a polymer material, for example made of at least one polymer material selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazoles, polyarylates and Teflon.

[0058] The base material layer 10 can have a single-layer structure. Alternatively, the base material layer 10 can have a multi-layer structure in which different polymer films 12 and 14 are stacked, as shown in Fig. 2 shown. If the base material layer 10 can have a multilayer structure, an adhesive layer 16a can be arranged between the polymer films.

[0059] The base material layer 10 can have a total thickness of approximately 10 µm to approximately 60 µm, preferably approximately 20 µm to approximately 50 µm, and more preferably approximately 30 µm to approximately 50 µm. If the base material layer has a multilayer structure, the thickness can include the adhesive layer. If the base material layer 10 meets the above range, durability, insulation, and formability can be excellent. If the thickness of the base material layer is too thin, durability may be reduced, and the base material layer may be damaged during the molding process. If the thickness is too thick, formability may be impaired, the overall thickness of the pouch may increase, and the battery capacity may be reduced, leading to a decrease in energy density.

[0060] According to one embodiment, the base material layer 10 can have a stacked structure consisting of a polyethylene terephthalate (PET) film and a nylon film. Here, the nylon film can be arranged on one side of the barrier layer 20, i.e., within the barrier layer 20, and the polyethylene terephthalate film can be arranged on a surface side of the pouch.

[0061] Polyethylene terephthalate (PET) can exhibit excellent durability and electrical insulating properties. Therefore, when the PET film is placed on the surface side, its durability and insulating properties can be excellent. However, in the case of PET film, because the adhesion to a thin aluminum alloy foil forming the barrier layer 20 is weak, and the elongation behavior differs when the PET film is placed on the barrier layer side, the base material layer and the barrier layer can peel off during the molding process, and the barrier layer cannot be stretched uniformly, leading to a deterioration in formability.In comparison, since the nylon film has a similar elongation behavior to the thin aluminum alloy film that forms the barrier layer 20, an effect of improved formability can be obtained when the nylon film is placed between the polyethylene terephthalate and the barrier layer.

[0062] The polyethylene terephthalate film can have a thickness of about 5 µm to about 20 µm, preferably about 5 µm to about 15 µm, more preferably about 7 µm to about 15 µm, and the nylon film can have a thickness of about 10 µm to about 40 µm, preferably about 10 µm to about 35 µm, more preferably about 15 µm to about 25 µm. If the thicknesses of the polyethylene terephthalate film and the nylon film meet the above ranges, the formability and stiffness after forming can be excellent. Barrier layer

[0063] The barrier layer 20 can be configured to ensure the mechanical strength of the pouch 100, to block the introduction and release of any gas or moisture outside the secondary battery, and to prevent electrolyte leakage.

[0064] The barrier layer 20 can have a thickness of approximately 40 µm to approximately 100 µm, preferably approximately 50 µm to approximately 80 µm, and preferably approximately 60 µm to approximately 80 µm. If the thickness of the barrier layer meets the above range, the formability can be improved to increase the trough molding depth or to improve resistance to external stress after molding, since fewer cracks and / or pinholes are formed, even when two troughs are formed.

[0065] The barrier layer 20 can be made of a metallic material and can in particular be made of a thin aluminum alloy foil.

[0066] The thin aluminum alloy foil may contain aluminum and one additional metal element besides the aluminum, for example at least one or two or more metal elements selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg) and zinc (Zn).

[0067] Preferably, the thin aluminum alloy foil can have an iron (Fe) content of about 1.2 wt.% to about 1.7 wt.%, preferably about 1.3 wt.% to about 1.7 wt.%, and more preferably about 1.3 wt.% to about 1.45 wt.%. If the iron (F2) content in the thin aluminum alloy foil meets the above range, the occurrence of cracks or pinholes can be minimized, even if the trough section is deep. Sealing layer

[0068] The sealing layer 30 can be configured to seal the pouch by being joined by thermal compression and can be arranged on the innermost layer of the pouch film layering 1.

[0069] Since the sealing layer 30 is a surface that comes into contact with the electrolyte and the electrode arrangement after the pouch has been formed, the sealing layer 30 may need to have insulation and corrosion resistance, and also, since the inside of the sealing layer 30 must be completely sealed to block the movement of the material between the inside and the outside, the sealing layer 30 may need to have height sealing capability.

[0070] The sealing layer 30 can be made of a polymer material, for example made of at least one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, polyparaphenylenebenzobisoxazoles, polyarylates and Teflon, and is particularly preferred to include polypropylene (PP) with excellent mechanical properties such as tensile strength, stiffness, surface hardness, abrasion resistance and heat resistance and chemical properties such as corrosion resistance.

[0071] In particular, the sealing layer may contain polypropylene 30, cast polypropylene (CPP), acid-modified polypropylene, a polypropylene-butylene-ethylene copolymer or a combination thereof.

[0072] The sealing layer 30 can have a single-layer structure or a multi-layer structure that includes two or more layers made of different polymer materials.

[0073] The sealing layer can have a total thickness of approximately 60 µm to approximately 100 µm, preferably approximately 60 µm to approximately 90 µm, and more preferably approximately 70 µm to approximately 90 µm. If the thickness of the sealing layer is too thin, the sealing durability and insulating properties may be impaired, and if the sealing layer is too thick, the flexibility may be impaired and the overall thickness of the pouch film layering may increase, leading to a reduction in energy density relative to volume.

[0074] For example, the pouch film layering can be produced by a process in which the base material layer 10 is attached to an upper surface of the barrier layer 20 by means of an adhesive and the sealing layer 30 is formed by co-extrusion or an adhesive on a lower surface of the barrier layer 20, but is not limited to this.

[0075] The Pouch 100 can be produced by inserting the pouch film layer, as described above, into a forming device and applying pressure to a portion of the pouch film layer using a die to form the tub section. The pressure can be approximately 0.3 MPa to approximately 1 MPa, preferably approximately 0.3 MPa to approximately 0.8 MPa, and more preferably approximately 0.4 MPa to approximately 0.6 MPa. If the pressure is too low during the forming of the tub section, excessive stretching and wrinkling may occur; conversely, if the pressure is too high, the stretching may not be effective, and the forming depth may be reduced.

[0076] The movement speed of the punch can be approximately 20 mm / min to approximately 80 mm / min, preferably approximately 30 mm / min to approximately 70 mm / min, and more preferably approximately 40 mm / min to approximately 60 mm / min. If the pressure is too low or the movement speed of the punch is too fast during forming, wrinkles may occur due to buckling; conversely, if the pressure is too high or the movement speed of the punch is too slow during forming, the stress concentrated in the trough section during forming may increase, leading to an increased occurrence of pinholes or cracks.

[0077] The pouch 100 produced by the above method can have a lower casing 101, an upper casing 102 and a folding section 130 connecting the lower casing to the lower casing, and the upper casing and / or the lower casing can have a basin section 110 that is recessed in one direction.

[0078] In particular, as in Fig.As shown in Figure 1, the pouch 100 can have a trough shape in which the trough section 110 is formed only in the lower housing 101, but is not limited to it. For example, the pouch 100 can have a 2-trough shape in which trough sections are formed on both the upper and lower housings. In the housing of the 2-trough pouch, after receiving the electrode array and the electrolyte, the upper housing can be folded so that the trough section of the upper housing and the trough section of the lower housing face each other, thus accommodating the electrode array, which is thicker than that of the pouch having the 1-trough shape, to implement a high energy density.

[0079] The well section 110 can have a receiving space for receiving the electrode assembly 200. The pouch 100 can have a terrace 120 around the well section 110. The terrace 120 can refer to an unformed section of the pouch film layering, that is, a remaining area excluding the well section 110. The terrace 120 can be a section that is tightly sealed by thermal bonding in a process of receiving the electrode assembly 200 in the well section 110 and introducing the electrolyte.

[0080] The basin section 110 can have a lower surface and a circumferential surface. The circumferential surface can connect a lower surface to the terrace 120. The circumferential surface can be provided in a plurality, more precisely, in four parts. The lower surface can cover a surface of the electrode arrangement 200, and the circumferential surface can surround the electrode arrangement 200.

[0081] The folding section 130 can connect the lower housing 101 to the upper housing 102, accommodate the electrode assembly 200 in the basin section 110 and introduce the electrolyte, and can then be folded to allow the upper housing 102 to tightly seal the basin section 110 of the lower housing 101. With the folding section 130 in place, since the lower housing 101 and the upper housing 102 are integrally connected, the number of sides to be sealed can be reduced later when the sealing process is performed, thus improving processability.

[0082] The folding section 130 is provided to be spaced apart from the basin section 110, and the distance between the folding section 130 and the basin section 110 can be approximately 0.5 mm to approximately 3 mm, preferably approximately 0.5 mm to approximately 2 mm. If the folding section 130 is provided too close to the basin section 110, the folding cannot be performed smoothly, and if the folding section 130 is provided too far from the basin section 110, the overall volume of the secondary battery may increase, and the energy density relative to the volume may decrease. In the housing of the 2-basin pouch, the folding section can be provided to maintain the required spacing for each basin section. Electrode arrangement

[0083] The electrode arrangement 200 can have multiple electrodes and multiple separators stacked alternately. The multiple electrodes have a positive electrode and a negative electrode, stacked alternately with the separator in between, and exhibiting opposite polarities.

[0084] Additionally, the electrode assembly 200 can have several electrode tabs 230 that are welded together. The multiple electrode tabs 230 can be connected to the multiple electrodes 210 and project outwards from the electrode assembly 200 to serve as a passage through which electrons can move between the inside and outside of the electrode assembly 200. The multiple electrode tabs 230 can be arranged in the pouch 100.

[0085] The electrode tab 230 connected to the positive electrode and the electrode tab 230 connected to the negative electrode can project outwards in different directions relative to the electrode arrangement 200. However, the present invention is not limited to this, and the electrode tab 230 connected to the positive electrode and the electrode tab 230 connected to the negative electrode can project outwards parallel to each other in the same direction.

[0086] A conductor 240, which supplies electricity to the outside of the secondary battery, can be connected to the multiple electrode tabs 230 by spot welding or the like. The conductor 240 can have one end connected to the multiple electrode tabs 230, and the other end can protrude to the outside of the pouch 100.

[0087] A section of the conduit 240 can be surrounded by an insulating section 250. For example, the insulating section 250 can have an insulating tape. The insulating section 250 can be arranged between the terrace 120 and the second housing 102 of the first housing 101, and in this state, the terrace 120 and the second housing 102 can be thermally fused together. In this case, a section of each of the terrace 120 and the second housing 102 can be thermally fused to the insulating section 250. Thus, the insulating section 250 can prevent the material generated by the electrode arrangement 200 from flowing through the conduit 240 to the pouch 100 and can maintain the seal of the pouch 100.

[0088] The ratio of the full length to the full width of the electrode arrangement 200 can be approximately 5 to approximately 10, preferably approximately 5 to approximately 8. If the ratio of the full length to the full width satisfies the above range, a high energy density can be implemented in a limited space.

[0089] For example, the electrode arrangement can have a full length of about 400 mm to about 600 mm, a full width of about 50 mm to about 150 mm, preferably a full length of about 500 mm to about 600 mm, and a full width of about 50 mm to about 100 mm.

[0090] The weight of the electrode assembly can range from 500 g to 1500 g, preferably from 550 g to 1450 g, and even more preferably from 600 g to 1400 g, without being limited thereto. If the weight of the electrode assembly falls within the above range, a high capacity can be achieved, and the friction between the electrode assembly and the inner surface of the battery casing increases, resulting in excellent shock resistance.

[0091] The secondary battery may further have at least one fastening element on the outer surface of the electrode assembly, if required. In the case of a rectangular electrode assembly (referred to for simplicity as a "long cell"), whose length is greater than its width, fastening elements are used to prevent misalignment of the electrode assembly components, such as the anode, cathode, and separator. The fastening element secures the electrode assembly by winding it in the width direction.

[0092] The fastening element can have a porous structure. If the fastening element has a porous structure, the electrolyte can pass through it and impregnate the electrode assembly, thus preventing the electrolyte wetting properties of the electrode assembly from being reduced by the fastening element. Specifically, the fastening element can be, but is not limited to, a sealing strip with an adhesive layer formed on one side of a polymer base layer having a porous structure. The polymer material can be, for example, polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyethylene (PE), etc.

[0093] The fastening element preferably has a width of approximately 10 to 50 mm or 20 to 40 mm along the full width direction of the electrode assembly. If the width of the fastening element is too wide, the outer surface area of ​​the electrode assembly covered by the fastening element increases, which can reduce electrolyte wetting properties due to a decrease in the contact area with the electrolyte and can reduce impact resistance due to a decrease in friction between the electrode assembly and the battery casing. Conversely, if the width of the fastening element is too narrow, the effectiveness of fastening the electrode assembly may be reduced.

[0094] The secondary battery can have 2 to 10 fastening elements, preferably 2 to 8 fastening elements, and more preferably 3 to 7 fastening elements. The fastening elements can be arranged in symmetrical positions along the length of the battery, and preferably they can be spaced at equal intervals. When multiple fastening elements are provided and arranged as described above, an electrode assembly having a long cell structure can be securely fastened.

[0095] Meanwhile, the contact area between the fastener and the electrode assembly can be 30% or less, 25% or less, or 20% or less of the total surface area of ​​the electrode assembly. Specifically, the contact area between the fastener and the electrode assembly can be 0 to 30%, 1 to 30%, 5 to 30%, 5 to 25%, or 5 to 20% of the total surface area of ​​the electrode assembly.

[0096] The contact area between the fastener and the electrode assembly can be adjusted by changing the width or number of fasteners used. Since the commonly used fastener is made of a material with a lower coefficient of friction than the separator located on the outermost surface of the electrode assembly, the friction between the electrode assembly and the inner surface of the battery casing will decrease as the area of ​​the fastener surrounding the electrode assembly increases. Therefore, when using a fastener, it is desirable to minimize this decrease in friction by reducing the contact area between the electrode assemblies to 30% or less. electrolyte

[0097] The electrolyte can be configured to move lithium ions generated by an electrochemical reaction of the electrode during charging and discharging of the secondary battery, and may include an organic solvent and lithium salt.

[0098] The organic solvent can be used without any particular restrictions, as long as it serves as a medium through which ions involved in the electrochemical reaction of the battery can move.In particular, examples of organic solvents may include: 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 dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents, such as ethyl alcohol and isopropyl alcohol; nitriles, such as R-CN (R is a straight-chain, branched, or cyclic C2 to C20 hydrocarbon group and may include a doubly bonded aromatic ring or an ether bond); amides, such as dimethylformamide; dioxolanes, such as 1,3-dioxolane; or sulfolanes. Among these, carbonate-based solvents are preferred, and cyclic carbonates (e.g. ethylene carbonate or propylene carbonate, etc.).) exhibit high ionic conductivity and high permittivity, which can increase the charging and discharging performance of the battery, and linear, low-viscosity carbonate-based compounds (e.g., a mixture of ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) are more preferred.

[0099] The lithium salt can be used without particular restriction, as long as it is a compound capable of providing lithium ions for use in the lithium secondary battery. In particular, the lithium salt can comprise LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, or the like. The concentration of the lithium salt can preferably be in the range of about 0.1 M to about 5.0 M, preferably about 0.1 M to about 3.0 M.

[0100] In addition to the electrolyte components, the electrolyte may also contain an adhesive to improve the battery's lifespan characteristics, suppress a decrease in battery capacity, and improve the battery's discharge capacity. Design 1

[0101] A pouch was fabricated in which a thin nylon / polyethylene terephthalate / aluminum alloy film / polypropylene was sequentially stacked to form a well section. A stacked electrode array, approximately 548 mm long, 99 mm wide, and weighing 1380 g, was placed within the well section, and an electrolyte was introduced in a tightly sealed manner. An activation process was then performed to create a pouch-shaped secondary battery. The electrolyte was introduced in such a way that the remaining amount of electrolyte per unit capacity after activation was approximately 2.2 g / Ah. Design 2

[0102] A pouch-shaped secondary battery was manufactured in the same way as in embodiment 1, except that the electrolyte is introduced such that a remaining amount of electrolyte per unit capacity after the activation process is approximately 2.15 g / Ah. embodiment 3

[0103] A pouch-shaped secondary battery was manufactured in the same manner as in embodiment 1, except that a stack-like electrode arrangement with a full length of about 548 mm, a full width of about 99 mm and a weight of 641 g is used, and the electrolyte is introduced such that a remaining amount of electrolyte per unit capacity after the activation process is about 1.7 g / Ah. Comparative example 1

[0104] A pouch-shaped secondary battery was manufactured in the same manner as in embodiment 1, except that a stack-like electrode arrangement with a full length of about 548 mm, a full width of about 99 mm and a weight of 641 g is used, and the electrolyte is introduced such that a remaining amount of electrolyte per unit capacity after the activation process is about 2.2 g / Ah. Comparative example 2

[0105] A pouch-shaped secondary battery was manufactured in the same way as in embodiment 1, except that the electrolyte is introduced such that a remaining amount of electrolyte per unit capacity after the activation process is approximately 2.3 g / Ah. Experiment 1: Friction force evaluation

[0106] In the pouch-shaped secondary batteries produced in embodiments 1 to 3 and comparative examples 1 to 2, the frictional force between the inner surface of the pouch tray and the electrode arrangement was measured by the following method.

[0107] A section of the secondary battery pouch was cut, a positive electrode tab was held with a clamping device connected to a wire, the wire was connected to a universal testing machine (UTM), and then the force exerted while the wire is pulled at a speed of about 100 mm / min was measured to assess the frictional force between the electrode assembly and the lower surface of the tub section. The measurement results are shown in Table 1 below. Test example 2: Crash shock test

[0108] A crash shock test was performed on the pouch-shaped secondary batteries manufactured in embodiments 1 to 3 and comparative examples 1 to 2 under a crash condition of 133.7 G × 15.8 ms. Measurement results are shown in Table 1 below. After the test, if no electrolyte leakage or electrode assembly separation occurred, it was marked as passed; if electrolyte leakage and / or electrode assembly separation occurred, it was marked as failed. [Table 1] Classification Full length [m] Full width[m] Remaining weight of electrolyte per unit capacity [g / Ah] W / S Frictional force [kgf] Result of the crash test Design 1 0,548 0,099 2,2 40,6 17,5 Passed Design 2 0,548 0,099 2,15 39,2 20,6 Passed embodiment 3 0,548 0,078 1,7 39,8 32,4 Passed Comparative example 1 0,548 0,078 2,2 51,5 11,6 Failed Comparative example 2 0,548 0,099 2,3 42,4 11,4 Failed

[0109] As shown in [Table 1], in the case of batteries according to embodiments 1 to 3, which have a W / S ratio of less than 42, the frictional force between the electrode assembly and the inner surface of the pouch was as high as about 15 kgf or more, and thus suppressed detachment of the electrode assembly by an external impact, thereby demonstrating excellent shock resistance. On the other hand, in the case of comparative examples 1 and 2, which have a W / S ratio of more than about 42, the frictional force was significantly reduced, and as a result, the electrolyte leaked out during the shock test.

[0110] If the size of the electrode arrangement and the amount of electrolyte per unit capacity meet the specific conditions of the secondary battery according to the present invention, the frictional force between the electrode arrangement and the battery housing can increase compared to the prior art, and thus, when an external shock is applied, detachment of the electrode arrangement and / or leakage of the electrolyte can be suppressed, and excellent shock resistance can be achieved.

[0111] Although the present invention has been shown and described in connection with the exemplary embodiments, it is obvious to the person skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the attached claims. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] KR 10-2022-0132745

[0001]

Claims

[1] Having a secondary battery: an electrode arrangement; an electrolyte; a battery casing that houses the electrode assembly and the electrolyte, where the secondary battery is configured to satisfy the following equation 1: W / S≤42(g / Ah)⋅m−2 where in equation 1 W is a weight of the electrolyte in g per unit capacity of the secondary battery in Ah and S is a product of a length in m and a width in m of the electrode arrangement. [2] Secondary battery according to claim 1, wherein the battery casing is a pouch. [3] Secondary battery according to claim 2, wherein the pouch is made from a pouch film layer, the pouch film layer comprising: a barrier layer; a base material layer arranged on a surface of the barrier layer; and a sealing layer that is arranged on the other surface of the barrier layer, wherein the pouch film layering is press-formed, in particular stretch-formed and / or drawn, so that it has one or more trough sections that project outwards, and the electrode arrangement is incorporated in one or more tub sections. [4] Secondary battery according to any of the preceding claims, wherein the W / S is in the range between 30 (g / Ah)·m -2 and 42 (g / Ah)·m -2 lies. [5] Secondary battery according to any of the preceding claims, wherein W in equation 1 is 2.2 g / Ah or less. [6] Secondary battery according to any of the preceding claims, wherein W in equation 1 is in the range between 1.5 g / Ah and 2.2 g / Ah. [7] Secondary battery according to one of the preceding claims, wherein S in equation 1 is in the range between 0.02 m2 and 0.09 m2. [8] Secondary battery according to one of the preceding claims, wherein the electrode arrangement in a top view has a substantially rectangular shape, such that the ratio of a length to a width of the electrode arrangement is in the range between 5 and 10. [9] Secondary battery according to one of the preceding claims, wherein the electrode arrangement in a top view has a substantially rectangular shape such that it has a length of 400 mm to 600 mm and a width of 50 mm to 150 mm. [10] Secondary battery according to any of the preceding claims, wherein the secondary battery is configured such that a frictional force between the electrode arrangement and an inner surface of the battery casing is 15 kgf or more. [11] Secondary battery according to one of the preceding claims, wherein the nominal capacity of the secondary battery is in the range between 50 Ah and 200 Ah. [12] Secondary battery according to one of the preceding claims, wherein when a crash shock test is performed on the secondary battery under a crash condition of 133.7 G × 15.8 m·s, the weight loss of the electrolyte due to leakage from the secondary battery is 0. [13] Secondary battery according to one of the preceding claims, wherein the electrolyte is arranged at least partially between the electrode arrangement and an inner surface of the battery housing which faces the electrode arrangement. [14] Having a secondary battery: an electrode arrangement with a surface area of ​​0.01 to 0.2 m2; an electrolyte weighing 440 g or less; a battery casing that houses the electrode assembly and the electrolyte, wherein the electrode arrangement, electrolyte and battery casing are configured such that a frictional force between the electrode arrangement and an internal surface of the battery casing is 15 kgf or more. [15] Secondary battery according to claim 14, wherein the electrolyte is arranged at least partially between the electrode arrangement and an inner surface of the battery housing which faces the electrode arrangement.

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