Battery cell, battery device and energy storage device

Abstract

The utility model discloses a battery cell, a battery device and an energy storage device. The single battery comprises a packaging bag and an electrode assembly located in the packaging bag, the electrode assembly comprises a plurality of positive plates, an isolating membrane and a negative plate, and the electrode assembly is a laminated electrode assembly; the length of the packaging bag is greater than or equal to 400mm; a storage space is arranged between the packaging bag and the electrode assembly, the storage space is arranged in a gap between the packaging bag and the electrode assembly, and the storage space is used for storing electrolyte; a bonding layer is arranged on the surface of at least one side of the isolating membrane and comprises a plurality of gluing areas and a plurality of non-gluing areas. The battery monomer provided by the utility model has good cycle performance.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular, to battery cells, battery devices, and energy storage devices. Background Art

[0002] Batteries are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. Improving the cycle life of secondary batteries is extremely important. It not only affects the economic and practical application of batteries, but also has profound impacts on the environment, technological development, and application areas.

[0003] Long-cell batteries (usually refers to lithium-ion batteries whose cells have a significantly extended shape in a certain dimension (usually axial or longitudinal) such as blade batteries) have shown significant application value in multiple fields due to their unique structural design and performance characteristics. This design achieves higher energy density and simpler system integration by increasing the effective energy storage volume of the cell monomer, but its cycle performance needs to be further improved. Utility Model Content

[0004] The first aspect of the present application provides a battery cell, including a packaging bag and an electrode assembly located in the packaging bag, the electrode assembly including multiple positive electrode sheets, a separator and a negative electrode sheet, and the electrode assembly is a laminated electrode assembly; the length of the packaging bag is ≥400 mm; a storage space is provided in the packaging bag, the storage space is arranged in the gap between the packaging bag and the electrode assembly, and the storage space is used to store electrolyte; at least one side surface of the separator is provided with an adhesive layer, and the adhesive layer includes multiple glue-coated areas and multiple non-glue-coated areas.

[0005] The adhesive layer on the isolation membrane proposed in this application has multiple adhesive areas and multiple non-adhesive areas. The adhesive areas bond the isolation membrane and the electrode; while the non-adhesive areas form flow channels between the isolation membrane and the electrode for circulating electrolyte, so that the electrolyte can enter the interface between the isolation membrane and the electrode through the flow channels, increasing the contact area between the electrode and the electrolyte, improving the electrolyte infiltration effect on the electrode, and helping to improve the problem of poor electrolyte infiltration effect when the battery is insufficient in the late cycle, thereby improving the battery's cycle performance. By providing a storage space in the packaging bag, the storage space is used to store electrolyte; especially when the amount of electrolyte is insufficient, the electrolyte in the storage space will gradually be released, and further infiltrate the electrode through the channels formed in the non-adhesive areas, thereby better improving the battery's cycle performance.

[0006] In some embodiments, the non-adhesive-coated area is in a strip-like structure.

[0007] In some embodiments, the width of the non-adhesive-coated area is 0.5 mm to 3 mm.

[0008] In some embodiments, the width of the non-glue-coated area is 0.5 mm to 1.5 mm.

[0009] In some embodiments, the width of the glue-coated area is 3 mm to 6 mm.

[0010] In some embodiments, the glue-coated area is in a strip-shaped structure, and multiple glue-coated areas of the strip-shaped structure are arranged in parallel along the length direction of the isolation film, and the gaps in the strip-shaped structure formed between adjacent glue-coated areas serve as non-glue-coated areas.

[0011] In some embodiments, the angle between the length direction of the non-adhesive-coated area and the length direction of the isolation film is 30° to 75°.

[0012] In some embodiments, the angle between the length direction of the non-adhesive-coated area and the length direction of the isolation film is 35° to 65°.

[0013] In some embodiments, the ratio of the area of the non-glue-coated region to the area of the glue-coated region is (1-5):6.

[0014] In some embodiments, the ratio of the area of the non-glue-coated region to the area of the glue-coated region is (1-4):6.

[0015] In some embodiments, a gap formed between an end of the packaging bag and an end of the electrode assembly at either end of the packaging bag in the length direction of the packaging bag serves as a storage space.

[0016] In some embodiments, the electrode assembly is located at either end of the packaging bag in the longitudinal direction, and the shortest straight-line distance between the end of the packaging bag and the end of the electrode assembly along the longitudinal direction of the packaging bag is 12 mm to 18 mm.

[0017] In some embodiments, the length of the packaging bag is 400 mm to 700 mm.

[0018] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode active film layer located on at least one side of the positive electrode current collector; the negative electrode sheet includes a negative electrode current collector and a negative electrode active film layer located on at least one side of the negative electrode current collector.

[0019] In some embodiments, the compaction density of the positive electrode active film layer is 2.3 g / cm 3 ~2.47g / cm 3 , and / or, the compaction density of the negative electrode active film layer is 1.4g / cm 3 ~1.55g / cm 3 .

[0020] In some embodiments, the porosity of the positive electrode active film layer is 23% to 30%, and / or the porosity of the negative electrode active film layer is 22% to 29%.

[0021] In some embodiments, the positive electrode active film layer comprises a positive electrode active material, and the positive electrode active material comprises lithium iron phosphate; and / or the negative electrode active film layer comprises a negative electrode active material, and the negative electrode active material comprises graphite.

[0022] In some embodiments, the battery cell further comprises an electrolyte having a viscosity of 1.0 mm 2 / s~2.6mm 2 / s.

[0023] A second aspect of the present application provides a battery device, comprising the battery cell provided in the first aspect.

[0024] The third aspect of the present application provides an energy storage device, comprising the battery cell provided in the first aspect, or comprising the battery device provided in the second aspect.

[0025] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0027] Figure 1 It is a schematic structural diagram of the adhesive layer on the surface of the diaphragm according to one embodiment of the present application.

[0028] Figure 2 It is a schematic structural diagram of the adhesive layer on the surface of the diaphragm according to one embodiment of the present application.

[0029] Figure 3 It is a schematic structural diagram of the adhesive layer on the surface of the diaphragm according to one embodiment of the present application.

[0030] Figure 4 It is a schematic structural diagram of the adhesive layer on the surface of the diaphragm according to one embodiment of the present application.

[0031] Figure 5 It is a structural schematic diagram of the adhesive layer on the surface of the diaphragm of one embodiment of the present application; wherein W1 represents the width of the non-glue-coated area, W2 represents the width of the glue-coated area, and α represents the angle between the length direction of the non-glue-coated area and the length direction of the diaphragm.

[0032] Figure 6 This is a schematic diagram of the principle of capillary adsorption of electrolyte in the non-glue-coated area of the diaphragm surface in one embodiment of the present application.

[0033] Figure 7 Schematic diagram of the structure of the adhesive layer on the surface of the diaphragm of Comparative Example 1.

[0034] Figure 8 Schematic diagram of the structure of the bonding layer on the surface of the diaphragm of Comparative Example 2.

[0035] Figure 9 It is a schematic structural diagram of a battery cell according to one embodiment of the present application.

[0036] Figure 10 yes Figure 9 A schematic structural diagram of a battery cell with marked dimensions; wherein D represents the shortest straight-line distance between the end of the packaging bag and the end of the electrode assembly, and L represents the length of the packaging bag.

[0037] Figure 11 Schematic diagram of a battery module according to one embodiment of the present application.

[0038] Figure 12 Schematic diagram of a battery pack according to one embodiment of the present application.

[0039] Figure 13 yes Figure 12 An exploded view of a battery pack according to an embodiment of the present application is shown.

[0040] Explanation of the marks in the accompanying drawings: 1 battery pack; 2 upper box; 3 lower box; 4 battery module; 5 battery; 6 base film; 7 glue-coated area; 8 non-glue-coated area; 9 packaging bag; 10 electrode assembly; 11 tab; 12 storage space. DETAILED DESCRIPTION

[0041] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0042] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0044] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0045] Currently, market developments indicate that batteries are increasingly being used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. As battery applications continue to expand, market demand is also growing.

[0046] Among them, long-cell batteries (generally referring to lithium-ion batteries with cells that exhibit significant extension in one dimension (usually axial or longitudinal), such as blade batteries, have demonstrated significant application value in multiple fields due to their unique structural design and performance characteristics. Furthermore, the significantly increased length of long cells makes them more suitable for lamination, which helps address issues such as uneven stress at the bends of the electrode sheets caused by the winding process, leading to reduced cycle life or increased internal resistance. However, long cells are prone to poor electrolyte wetting, which can reduce cycle life. This is because the larger size of long cells increases the diffusion distance of the electrolyte in the radial and longitudinal directions. In the presence of insufficient electrolyte, certain areas of the cell may not be fully wetted, particularly in the center of the cell. Poor electrolyte wetting leads to uneven distribution of lithium ions on the electrode surface, which can trigger lithium plating and lead to a sharp decline in battery performance during cycling, manifested as rapid capacity decay, known as "cycle dive." In addition, the separator is usually a glue-coated separator, which can firmly bond the positive electrode sheet to the separator, and the separator to the negative electrode sheet through the glue layer (i.e., bonding layer), and has high requirements for the bonding strength of the composite interface. At present, the glue-coated separator is often prepared by fully coating the surface of the separator (such as roller coating), forming a continuous glue layer on the surface of the separator, which leads to an increase in the resistance of the electrolyte entering and infiltrating the interface between the separator and the electrode, thereby affecting the cycle performance of the battery.

[0047] To this end, a first aspect of an embodiment of the present application provides a battery cell, including a packaging bag and an electrode assembly located in the packaging bag, wherein the electrode assembly includes a plurality of positive electrode sheets, a separator, and a negative electrode sheet, and the electrode assembly is a laminated electrode assembly;

[0048] The length of the packaging bag is ≥400mm;

[0049] A storage space is provided between the packaging bag and the electrode assembly. The storage space is provided in the gap between the packaging bag and the electrode assembly, and the storage space is used to store electrolyte;

[0050] At least one side surface of the isolation film is provided with an adhesive layer, and the adhesive layer includes a plurality of adhesive-coated areas and a plurality of non-adhesive-coated areas.

[0051] like Figure 1-6 As shown, in the embodiment of the present application, the adhesive layer on the separator has multiple adhesive areas 7 and multiple non-adhesive areas 8. The adhesive areas bond the separator to the electrode, while the non-adhesive areas 8 form flow channels for electrolyte flow between the separator and the electrode. This allows electrolyte to enter the interface between the separator and the electrode through the flow channels, increasing the contact area between the electrode and the electrolyte and improving the electrolyte wetting effect on the electrode. This helps to improve the poor electrolyte wetting effect in the battery when the battery is insufficient in the late cycle, thereby improving the battery's cycle performance. A storage space is provided between the packaging bag 9 and the electrode assembly 10 to store electrolyte. Especially when the electrolyte is insufficient, the electrolyte in the storage space is gradually released and further wets the electrode through the channels formed by the non-adhesive areas 8, thereby further improving the battery's cycle performance. In addition, the storage space is provided in the gap between the packaging bag 9 and the electrode assembly 10, which does not affect the main structure of the electrode assembly 10 and facilitates the infiltration of electrolyte into the interface between the separator and the electrode through the flow channels of the non-adhesive areas 8.

[0052] As an example, the length of the packaging bag is 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, 1000 mm, etc.

[0053] As an example, the packaging bag 9 is a soft bag packaging bag.

[0054] In some embodiments, the shape of the non-glue-coated area 8 can be a trapezoid (e.g. Figure 1 as shown), ribbon (as an example, Figure 2 The rectangle shown, Figure 3 The length direction of the non-glue-coated area 8 can be perpendicular to the length direction of the isolation film (such as Figure 2 As shown), it can also be in the same direction as the length direction (as shown Figure 4 As shown), it can also be tilted, with a certain angle to the length direction (as shown Figure 3 shown).

[0055] In some embodiments of the present application, the non-glue-coated area 8 is in a strip-shaped structure.

[0056] In the embodiment of the present application, the non-glue-coated area 8 can be a strip-shaped structure, which is beneficial to the circulation of the electrolyte, shortening the circulation path of the electrolyte, better exerting the capillary effect, improving the wetting performance of the electrolyte, and enhancing the cycle performance of the battery.

[0057] In addition, long-cell stacked batteries have high requirements for the adhesion strength of the composite interface between the separator and the electrode. Currently, the common method of preparing a glue-coated separator is to fully coat the separator surface (such as roller coating). This method forms a continuous glue layer on the separator surface with a high coverage rate to achieve interfacial adhesion, which is prone to demolding problems. This is because the composite interface adhesion strength is much higher than the bonding strength within the electrode. The stress will be concentrated at the interface between the active film layer of the electrode and the current collector, causing the latter to become a "weak point" and fall off. During the battery cycle, the electrode will experience demolding during the frequent expansion and contraction process, thereby worsening the battery's cycle performance. Different from the roller coating method for preparing glue-coated separators, the inventors have tried to prepare glue-coated separators by spraying. This method forms a discontinuous island-shaped glue layer on the separator surface with a low coverage rate in the hope of alleviating the demolding problem. However, the bonding strength between the separator and the electrode cannot meet the requirements, resulting in the battery's cycle performance not being effectively improved.

[0058] The bonding layer proposed in the embodiment of the present application is formed by multiple glue-coated areas 7 and multiple non-glue-coated areas 8. This enables a certain amount of non-glue-coated areas 8 to exist in the bonding layer, reducing the continuity of the glue-coated areas 7, which is beneficial to alleviating the demolding phenomenon while maintaining the overall bonding performance of the bonding layer.

[0059] In some embodiments of the present application, the width of the non-glue-coated area 8 is 0.5 mm to 3 mm.

[0060] Testing can be performed using methods known in the art, such as optical microscopy. For example, the adhesive-coated area 7 and the non-adhesive-coated area 8 of the separator have different morphologies (the adhesive-coated area 7 will adhere to the powder, resulting in a yellowish or slightly darker separator, while the non-adhesive-coated area 8 is white). Using an optical microscope equipped with a cross-hair eyepiece (such as the Olympus BX53M), calibrate the scale graduations (e.g., 1 grid = 50 μm) under a 20x objective lens. Select five equally spaced measurement points along the length of the flow channel (including the maximum and minimum width areas). The width is calculated by reading the difference in the number of scale grids corresponding to the two sides of the non-adhesive-coated area 8. For the same non-adhesive-coated area 8, the width of all selected measurement points can be the same or different.

[0061] As an example, the width of the non-glue-coated area 8 is 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3 mm, etc.

[0062] In the embodiment of the present application, the width of the non-coated area 8 meets the above conditions: on the one hand, it is conducive to improving the infiltration effect of the electrolyte, thereby improving the cycle performance of the battery. This is because: 1) Compared with the fully coated separator, the bonding interface between the separator and the electrode will hinder the electrolyte from infiltrating the electrode. The electrolyte mainly infiltrates the electrode through the exposed side of the battery electrode. The non-coated area 8 provided in the embodiment of the present application can provide a new transmission path for the electrolyte, prompting more electrolyte to be transmitted to the composite interface between the separator and the electrode, thereby improving the infiltration effect; 2) By designing the flow channel width of the non-coated area 8 to meet the above conditions, it is conducive to forming a capillary absorption effect, providing power for electrolyte transmission, improving electrolyte transmission efficiency, and better infiltrating the electrode. On the other hand, it is conducive to effectively balancing the reduction of demoulding problems and improving the overall bonding performance of the bonding layer, ensuring that the battery separator of the present application can effectively alleviate the demoulding problem while showing a higher bonding strength, thereby improving the cycle performance of the battery.

[0063] like Figure 5 As shown in the figure, a glue-coated area 7 and a non-glue-coated area 8 on the surface of the isolation film are shown, the width of the non-glue-coated area 8 is W1, and the width of the glue-coated area 7 is W2.

[0064] In some embodiments of the present application, the width of the non-glue-coated area 8 is 0.5 mm to 1.5 mm.

[0065] In the embodiments of the present application, the width of the non-adhesive region 8 satisfies the aforementioned conditions. This, on the one hand, further improves the electrolyte infiltration effect, thereby further enhancing the battery's cycling performance. On the other hand, it helps to better balance reducing mold release issues and improving the overall bonding performance of the adhesive layer, further ensuring that the battery separator of the present application can effectively alleviate mold release issues while exhibiting higher bonding strength, further improving the battery's cycling performance.

[0066] In some embodiments of the present application, the width of the glue-coated area 7 is 3 mm to 6 mm.

[0067] Inspection can be performed using methods known in the art, such as optical microscopy. For example, the adhesive-coated area 7 and the non-adhesive-coated area 8 of the separator have different morphologies (the adhesive-coated area 7 will adhere to the powder, resulting in a yellowish or slightly darker separator, while the non-adhesive-coated area 8 is white). Using an optical microscope equipped with a cross-scale eyepiece (such as the Olympus BX53M), calibrate the scale graduations (e.g., 1 grid = 50 μm) under a 20x objective lens. Select five equally spaced measurement points along the length of the adhesive-coated area 7 (including the areas with the maximum and minimum widths). The width is calculated by reading the difference in the number of scale grids corresponding to the two sides of the adhesive-coated area 7. For the same adhesive-coated area 7, the width of all selected measurement points can be the same or different.

[0068] As an example, the width of the glued area 7 is 3 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4 mm, 4.2 mm, 4.4 mm, 4.6 mm, 4.8 mm, 5 mm, 5.2 mm, 5.4 mm, 5.6 mm, 5.8 mm, 6 mm, etc.

[0069] In the embodiment of the present application, the width of the glue-coated area 7 meets the above conditions, which is beneficial to alleviate the problem of electrode demolding while further improving the bonding strength between the isolation membrane and the electrode, thereby improving the cycle performance of the battery.

[0070] In some embodiments of the present application, the glue-coated area 7 is in a strip-shaped structure, and multiple strip-shaped glue-coated areas 7 are arranged in parallel along the length direction of the isolation membrane, and the gaps in the strip-shaped structures formed between adjacent glue-coated areas 7 serve as non-glue-coated areas 8.

[0071] In the embodiment of the present application, the strip-shaped adhesive-coated regions 7 and the strip-shaped non-adhesive-coated regions 8 are alternately arranged, resulting in a striped adhesive layer. Under capillary action, the electrolyte forms flow channels through the non-adhesive-coated regions 8, achieving effective wetting of the electrode. Furthermore, the strip-shaped adhesive-coated regions 7 facilitate the preparation of the adhesive layer, for example, by directly using a roller coating method.

[0072] In some embodiments of the present application, the angle between the length direction of the non-glue-coated area 8 and the length direction of the isolation film is 30° to 75°.

[0073] In the embodiments of the present application, an optical microscope can be used for detection. As an example, an optical microscope with a cross-scale eyepiece (such as an Olympus BX53M) is used. The scale graduation is calibrated under a 20x objective lens (for example, 1 division = 50 μm). The length direction of the isolation film is used as the horizontal plane. Five non-adhesive areas 8 are selected. The angle between the longitudinal extension direction of the non-adhesive areas 8 and the horizontal line is measured, and the average value is taken to obtain the aforementioned angle.

[0074] As an example, the angle between the length direction of the non-glue-coated area 8 and the length direction of the isolation membrane is 30°, 32°, 34°, 36°, 38°, 40°, 42°, 44°, 46°, 48°, 50°, 52°, 54°, 56°, 58°, 60°, 62°, 64°, 66°, 68°, 70°, 72°, 74°, 75°, etc.

[0075] In the later stages of the battery cycle, when the electrolyte is about to be exhausted, one side of the separator faces downward, such as the side of the separator parallel to its length, and contacts the remaining electrolyte in the packaging bag 9. At this time, one end of the flow channel formed by the non-coated area 8 contacts the electrolyte. Under the capillary action of the flow channel, the electrolyte enters the flow channel through the port of the flow channel and climbs upward along the flow channel, infiltrating the electrode, improving the electrolyte infiltration effect, and thus helping to improve the battery cycle performance. When the angle between the length direction of the non-coated area 8 and the length direction of the separator is small, the electrolyte's climbing distance increases, and the improvement effect on the electrolyte infiltration effect will show a downward trend; when the angle between the length direction of the non-coated area 8 and the length direction of the separator is large, the electrolyte is more affected by gravity when climbing along the flow channel, and the improvement effect on the electrolyte infiltration effect will also show a downward trend.

[0076] like Figure 5 As shown in the figure, the adhesive coating area 7 and the non-adhesive coating area 8 on the surface of the isolation film are shown. The non-adhesive coating area 8 is tilted, and the angle between the length direction of the non-adhesive coating area 8 and the length direction of the isolation film is α.

[0077] In some embodiments of the present application, the angle between the length direction of the non-glue-coated area 8 and the length direction of the isolation film is 35° to 65°.

[0078] In the embodiment of the present application, the angle between the length direction of the non-glue-coated area 8 and the length direction of the isolation membrane meets the above conditions. The climbing distance of the electrolyte along the flow channel formed by the non-glue-coated area 8 is shorter, and the effect of gravity on the climbing of the electrolyte is smaller, thereby further improving the capillary effect of the flow channel formed by the non-glue-coated area 8, increasing the circulation efficiency of the electrolyte, better improving the infiltration effect of the electrolyte, and further better improving the cycle life of the battery.

[0079] In some embodiments of the present application, the ratio of the area of the non-glue-coated region 8 to the area of the glue-coated region 7 is (1-5):6.

[0080] As the area ratio of the non-coated area 8 to the coated area 7 gradually decreases, the risk of demolding of the electrode will also tend to increase; as the area ratio of the non-coated area 8 to the coated area 7 gradually increases, the overall adhesion of the adhesive layer will tend to decrease. Therefore, the area ratio of the non-coated area 8 to the coated area 7 that meets the above conditions is conducive to effectively balancing the mitigation of demolding problems and improving the overall adhesion performance of the adhesive layer, thereby improving the cycle performance of the battery. As an example, the area ratio of the non-coated area 8 to the coated area 7 is 1:6, 2:6, 3:6, 4:6, 5:6, etc.

[0081] In some embodiments of the present application, the ratio of the area of the non-glue-coated region 8 to the area of the glue-coated region 7 is (1-4):6.

[0082] The ratio of the area of the non-glue-coated area 8 to the area of the glue-coated area 7 meets the above conditions, which is conducive to further effectively alleviating the demoulding problem while showing higher bonding strength, thereby further improving the cycle performance of the battery.

[0083] The solution proposed in the embodiment of the present application can be applied to long-cell batteries, which is beneficial to improving the problem of pole piece demoulding, having higher bonding stability between the isolation film and the pole piece, and is beneficial to improving the cycle life of the battery.

[0084] In some embodiments of the present application, the battery cell provided in the embodiments of the present application is installed with the side surface of the battery cell and the bottom surface of the battery pack in affixed fit when in use. At this time, the length direction of the isolation membrane is in the same direction as the horizontal direction, and the side edge of the isolation membrane faces downward.

[0085] In the embodiments of the present application, the separator can be installed with its length aligned with the horizontal direction, with its side facing downward. In particular, when the non-adhesive-coated region 8 is strip-shaped and the angle between the strip's length and the separator's length is 30°-75°, this facilitates the upward migration of the electrolyte along the flow path formed by the non-adhesive-coated region 8 under capillary action, shortening the electrolyte's migration distance, improving electrolyte wetting, and further enhancing the battery's cycle life.

[0086] When there is insufficient electrolyte, the electrolyte in the storage space is gathered to the bottom side of the isolation membrane under the action of gravity, so that the flow channel formed in the non-coated area 8 can absorb and transport the electrolyte under capillary action, thereby improving the infiltration effect of the electrolyte and improving the cycle performance of the battery.

[0087] As an example, Figure 6 As shown in the figure, the battery cell is horizontally placed, and the separator is also in a horizontal position. In the late cycle of the battery cell, the electrolyte is about to be exhausted, as shown in the figure. Figure 6 The dotted area shown in A represents the remaining electrolyte. The electrolyte on the outside of the isolation membrane can pass through the flow channel formed by the non-glue-coated area 8, enter the non-glue-coated area 8 under the capillary action of the non-glue-coated area 8, and enter the interface between the isolation membrane and the electrode, thereby achieving effective infiltration of the electrode. Figure 6 In the figure, the direction of the arrow indicates the flow direction of the electrolyte in the non-coated area 8.

[0088] In some embodiments of the present application, the material used for the adhesive coating area 7 can be a coating material known in the art, that is, a known adhesive. As an example, the material used for the adhesive coating area 7 includes one or a combination of PVDF (polyvinylidene fluoride) and PMMA (polymethyl methacrylate).

[0089] PVDF or PMMA has been widely used in lithium battery adhesive separators, and the batteries exhibit high electrical performance and safety.

[0090] In some embodiments of the present application, a gap formed between an end of the packaging bag 9 and an end of the electrode assembly 10 at any end in the length direction of the packaging bag 9 along the length direction of the packaging bag 9 serves as a storage space.

[0091] like Figure 9 and Figure 10 As shown, the battery cell includes a packaging bag 9, an electrode assembly 10 and a tab 11. The positive electrode sheet, the negative electrode sheet and the separator are laminated to form the electrode assembly 10, and the electrode assembly 10 is encapsulated in the packaging bag 9. One end of the tab 11 is welded to the current collector of the electrode assembly 10, and the other end passes through the sealed edge of the packaging bag 9. The electrolyte is infiltrated into the electrode assembly 10. The number of electrode assemblies 10 contained in the battery can be one or more, and those skilled in the art can select according to specific actual needs. A space is formed between the end of the electrode assembly 10 in the longitudinal direction and the inner wall of the packaging bag 9 on the corresponding side as a storage space 12, which serves as a reserved electrolyte storage space for storing electrolyte.

[0092] In some embodiments of the present application, the length L of the packaging bag 9 is ≥ 400 mm. The length L of the packaging bag 9 is the length of the main structure of the battery cell, that is, the sum of the length of the electrode assembly 10 and the length of the electrode tabs 11 at both ends of the electrode assembly 10 in the longitudinal direction, which do not extend beyond the sealed edge of the packaging bag 9. The shortest straight-line distance D between the end of the packaging bag 9 and the end of the electrode assembly 10 at either end of the longitudinal direction of the packaging bag 9 and along the longitudinal direction of the packaging bag 9 is 12 mm to 18 mm.

[0093] In the embodiments of the present application, the shortest straight-line distance between the end of the packaging bag 9 and the end of the electrode assembly 10 reflects the size of the storage space. Given that the widths of the packaging bag 9 and the electrode assembly 10 remain unchanged, the smaller the minimum straight-line distance, the smaller the storage space; the larger the minimum straight-line distance, the larger the storage space. Satisfying the above-mentioned minimum straight-line distance between the end of the packaging bag 9 and the end of the electrode assembly 10 facilitates the storage of an effective amount of electrolyte. In the event of electrolyte shortage at a later stage, electrolyte replenishment can be released to improve electrolyte infiltration of the electrode sheets. Furthermore, this helps conserve space and ensures that the battery meets energy density requirements.

[0094] As an example, the shortest straight-line distance between the end of the packaging bag 9 and the end of the electrode assembly 10 is 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, etc.

[0095] In some embodiments of the present application, the length of the packaging bag is 400 mm to 700 mm.

[0096] In some embodiments of the present application, the positive electrode sheet includes a positive electrode current collector and a positive electrode active film layer located on at least one side of the positive electrode current collector; the negative electrode sheet includes a negative electrode current collector and a negative electrode active film layer located on at least one side of the negative electrode current collector.

[0097] In some embodiments of the present application, the compaction density of the positive electrode active film layer is 2.3 g / cm 3 ~2.47g / cm 3 , and / or, the compaction density of the negative electrode active film layer is 1.4g / cm 3 ~1.55g / cm 3 .

[0098] The compaction density has a meaning well known in the art and can be measured using methods well known in the art. For example, if a fresh battery is disassembled at 0% charge after storage, a certain area (s) of electrode is cut and weighed. The electrode weight, electrode thickness, and thickness of the current collector (such as copper foil, aluminum foil, etc.) are measured. The weight of the current collector can be calculated based on the thickness and density of the current collector. The weight of the active membrane layer is the weight of the electrode minus the weight of the current collector, and the thickness of the active membrane layer is the thickness of the electrode minus the thickness of the current collector. The weight A of the active membrane layer per unit area is then calculated and divided by the thickness of the active membrane layer to calculate the compaction density.

[0099] As an example, the compaction density of the positive electrode sheet is 2.3g / cm 3 , 2.31g / cm 3 , 2.33g / cm 3 , 2.35g / cm 3 , 2.37g / cm 3 , 2.39g / cm 3 , 2.41g / cm 3 , 2.43g / cm 3 , 2.45g / cm 3 , 2.47g / cm 3 wait.

[0100] As an example, the compaction density of the negative electrode sheet is 1.4 g / cm 3 , 1.41g / cm 3 , 1.43g / cm 3 , 1.45g / cm 3 , 1.47g / cm 3 , 1.49g / cm 3 , 1.51g / cm 3 、1.53g / cm 3 , 1.55g / cm 3 wait.

[0101] In the embodiment of the present application, the compaction density of the positive electrode and / or the negative electrode is designed to meet the above conditions, and the compaction density is relatively small. On the one hand, it is beneficial to improve the effect of the electrode itself absorbing the electrolyte; on the other hand, the effect of the electrode absorbing the electrolyte is increased, which is beneficial to promote the circulation of the electrolyte in the flow channel formed by the non-glue-coated area 8, further enhance the infiltration effect of the electrolyte on the electrode, and thus improve the cycle performance of the battery.

[0102] In some embodiments of the present application, the compaction density of the positive electrode sheet is 2.35 g / cm 3 ~2.45g / cm 3 , and / or, the compaction density of the negative electrode sheet is 1.43g / cm 3 ~1.53g / cm 3 .

[0103] In the embodiment of the present application, the compaction density of the positive electrode sheet and / or the negative electrode sheet meets the above conditions, which is conducive to better improving the wetting effect of the electrolyte on the electrode sheet and further improving the cycle performance of the battery.

[0104] In some embodiments of the present application, the porosity of the positive electrode active film layer is 23% to 30%, and / or the porosity of the negative electrode active film layer is 22% to 29%.

[0105] As an example, the porosity of the positive electrode active film layer is 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc.

[0106] As an example, the porosity of the negative electrode active film layer is 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, etc.

[0107] In some embodiments of the present application, the positive electrode active film layer contains a positive electrode active material, and the positive electrode active material includes lithium iron phosphate; and / or the negative electrode active film layer contains a negative electrode active material, and the negative electrode active material includes graphite.

[0108] In some embodiments of the present application, the battery cell further includes an electrolyte having a viscosity of 1.0 mm 2 / s~2.6mm 2 / s.

[0109] The viscosity of the electrolyte has a well-known meaning in the art and can be measured using methods well-known in the art. For example, the viscosity can be measured with reference to the national standard GB / T 9725-2007.

[0110] As an example, the viscosity of the electrolyte is 1.0 mm 2 / s、1.2mm 2 / s、1.4mm 2 / s、1.6mm 2 / s、1.8mm 2 / s, 2.0mm 2 / s、2.2mm 2 / s, 2.4 mm 2 / s、2.6mm 2 / s, etc.

[0111] In the embodiment of the present application, the viscosity of the electrolyte meets the above conditions, which is conducive to improving the fluidity of the electrolyte. On the one hand, it is conducive to increasing the effect of the electrolyte directly infiltrating the electrode; on the other hand, since the rate at which the electrode absorbs the electrolyte increases, it is conducive to promoting the rate at which the non-coated area 8 absorbs the electrolyte through capillary action, thereby better improving the overall electrolyte infiltration effect on the electrode and improving the cycle performance of the battery.

[0112] Furthermore, the electrolyte includes a solvent, and the solvent includes a linear carbonate solvent.

[0113] Furthermore, the solvent includes one or a combination of DMC (dimethyl carbonate) and EMC (ethyl methyl carbonate).

[0114] Furthermore, the solvent includes DMC and EMC; based on the total mass of the electrolyte, the mass percentage of DMC is 15% to 25%, and the mass percentage of EMC is 40% to 55%.

[0115] In one embodiment of the present application, a battery cell is provided.

[0116] Typically, a battery cell consists of a positive electrode, a negative electrode, an electrolyte, and a separator. During the battery's charge and discharge processes, active ions are inserted and removed between the positive and negative electrodes. The electrolyte conducts ions between the positive and negative electrodes. The separator, located between the positive and negative electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through.

[0117] [Positive electrode]

[0118] The positive electrode sheet includes a positive electrode current collector and a positive electrode active film layer provided on at least one surface of the positive electrode current collector, wherein the positive electrode active film layer includes a positive electrode active material.

[0119] As an example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode active film layer is disposed on either or both of the two opposite surfaces of the positive electrode current collector.

[0120] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0121] In some embodiments, the positive electrode active film layer may further optionally include a binder. For example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0122] In some embodiments, the positive electrode active film layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0123] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0124] [Negative electrode]

[0125] The negative electrode sheet includes a negative electrode current collector and a negative electrode active film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode active film layer includes a negative electrode active material.

[0126] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active film layer is disposed on either or both of the two facing surfaces of the negative electrode current collector.

[0127] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0128] In some embodiments, the negative electrode active film layer may further include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0129] In some embodiments, the negative electrode active film layer may further include a conductive agent, which may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0130] In some embodiments, the negative electrode active film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0131] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0132] [Electrolytes]

[0133] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. This application has no specific restrictions on the type of electrolyte, and it can be selected according to needs.

[0134] In some embodiments, the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.

[0135] In some embodiments, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonyl imide, lithium bistrifluoromethanesulfonyl imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium bisoxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0136] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0137] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0138] [Isolation film]

[0139] In some embodiments, the battery further includes a separator, such as the separator described in the first aspect of the embodiment of the present application.

[0140] In some embodiments, the battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0141] In some embodiments, the outer packaging of the battery cell may be a soft package, such as a bag-type soft package. The soft package may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0142] A second aspect of the embodiments of the present application provides a battery device, including the battery cell provided in the first aspect of the embodiments of the present application.

[0143] The battery device may be a battery module assembled from battery cells. The number of battery cells contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0144] Figure 11 4 is an example of a battery module. Figure 11 In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. The plurality of battery cells 5 may further be fixed by fasteners.

[0145] Optionally, the battery module 4 may further include a housing having an accommodation space, and the plurality of battery cells 5 are accommodated in the accommodation space.

[0146] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0147] Figure 12 and Figure 13 The battery pack 1 is used as an example. Figure 12 and Figure 13 The battery pack 1 may include a battery box and multiple battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner in the battery box.

[0148] As an electrical device, a battery, battery module or battery pack can be selected according to its usage requirements.

[0149] A third aspect of the embodiments of the present application provides an energy storage device, including the battery cell provided in the first aspect of the embodiments of the present application, or including the battery device provided in the second aspect of the embodiments of the present application.

[0150] The batteries proposed in the embodiments of this application are suitable for long-life scenarios, such as energy storage devices. Energy storage battery systems (such as grid-level energy storage, home energy storage, and renewable energy support) typically require 24 / 7 uninterrupted operation and high charge and discharge frequencies (multiple cycles per day). For example, grid frequency regulation energy storage may undergo hundreds of charge and discharge cycles per day. If the battery life is short, frequent replacement will cause the system to shut down, threatening the stability of the grid. In addition, based on requirements such as economy, safety, and sustainable development, energy storage batteries are required to have a long cycle life.

[0151] The battery proposed in the embodiment of the present application can be applied to energy storage batteries, which is beneficial to improving the infiltration effect of the electrolyte, improving the problem of electrode demolding, having higher bonding stability between the isolation film and the electrode, and improving the cycle life of the battery.

[0152] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0153] Preparation of lithium-ion batteries

[0154] Example 1

[0155] 1) Preparation of positive electrode

[0156] The positive electrode active material lithium iron phosphate (LiFePO4), the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) were dissolved in the solvent N-methylpyrrolidone (NMP) at a weight ratio of 97:1:2, and the mixture was thoroughly stirred to obtain a positive electrode slurry. The positive electrode slurry was then evenly coated on the positive electrode current collector aluminum foil, and then dried, cold pressed, and cut to obtain a positive electrode sheet. The compaction density of the positive electrode sheet is 2.36g / cm 3 .

[0157] 2) Preparation of negative electrode sheet

[0158] Graphite, conductive carbon black, binder styrene-butadiene rubber, and dispersant sodium carboxymethyl cellulose were mixed in a mass ratio of 96.5:1:1.5:1, and deionized water was added and stirred thoroughly to form a negative electrode slurry. The negative electrode slurry was evenly coated on one surface of the negative electrode current collector copper foil, and after drying and cold pressing, a negative electrode sheet was obtained. The compaction density of the negative electrode sheet was 1.45 g / cm 3 .

[0159] 3) Preparation of isolation membrane

[0160] The adhesive-coated isolation film was prepared by roller coating. Specifically, a polyethylene film with a thickness of 7 μm was used as the base film 6, and PVDF (polyvinylidene fluoride) was used as the adhesive material. Stripe-shaped gap coating was formed on the base film by roller coating at a certain angle.

[0161] Finally, the isolation film obtained has a width W1 of the non-glue-coated area 8 of 1 mm, a width W2 of the glue-coated area 7 of 4 mm, and an angle α between the length direction of the non-glue-coated area 8 and the length direction of the isolation film of 45°. Figure 5 shown.

[0162] 4) Preparation of electrolyte

[0163] Ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and ethylene carbonate (EC) are mixed to form a mixed solvent. Based on the total mass of the electrolyte, the mass percentage of DMC is 20%, the mass percentage of EMC is 45%, and the mass percentage of EC is 35%. Thoroughly dried lithium salt LiPF6 is then dissolved in the mixed solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0164] 5) Battery Preparation

[0165] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator positioned between the positive and negative electrodes to provide insulation. The cells are then thermally laminated to produce bare cells. The tabs 11 are welded to the bare cells and placed in a 400mm-long soft packaging bag. The bag is then baked at 80°C to remove moisture, and then electrolyte is injected and sealed to produce an uncharged battery. The gap between the end of the soft packaging bag and the end of the electrode assembly 10 serves as storage space 12. The shortest straight-line distance D between the end of the soft packaging bag and the end of the electrode assembly 10 is 14mm. The uncharged battery then undergoes a series of processes, including resting, hot and cold pressing, formation, shaping, and capacity testing, to produce a lithium-ion battery product.

[0166] Example 2-12

[0167] Examples 2-12 use the method of Example 1 to prepare batteries, and the specific differences are shown in Table 1.

[0168] Comparative Example 1

[0169] The battery was prepared by the method of Example 1, except that the adhesive-coated separator was prepared by roller coating, and the adhesive layer was fully coated on the surface of the base film. Figure 7 shown.

[0170] Comparative Example 2

[0171] The battery was prepared by the method of Example 1, except that the adhesive-coated diaphragm was prepared by spraying, and a discontinuous island-shaped adhesive layer was prepared on the surface of the base film. Figure 8 shown.

[0172]

Performance test

[0173] 1. Test Method

[0174] 1. Dislocation ratio

[0175] Perform X-ray scanning on the assembled battery cells. After the positive and negative electrodes are stacked, products where the edge of the positive electrode is not covered by the negative electrode are marked as defective. Test 10,000 cells continuously and calculate the defective ratio.

[0176] 2. Cycle performance

[0177] At 25°C, charge the prepared battery at 0.5C to 3.65V, then discharge it at 0.5C to 2.5V. This constitutes one charge-discharge cycle. Record the discharge capacity at this point, which is the initial discharge capacity. Continue cyclically charging and discharging the battery as described above, recording the discharge capacity after each cycle until the discharge capacity of the secondary battery decays to 80% of the initial discharge capacity. Record the number of cycles at this point.

[0178] 2. Test Results

[0179] Table 1

[0180]

[0181] Table 1 shows the performance test results for various examples and comparative examples. By providing a plurality of adhesive-coated and non-adhesive-coated regions on the base film to form a striped adhesive layer, the present invention improves electrolyte wetting and enhances battery cycle performance. Furthermore, by optimizing various design parameters, such as the width of the non-adhesive-coated and adhesive-coated regions, and the angle between the two regions, battery cycle performance is further improved, while the misalignment ratio is reduced, resulting in superior bonding performance.

[0182] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A battery cell, characterized in that: The invention comprises a packaging bag and an electrode assembly located in the packaging bag, wherein the electrode assembly comprises a plurality of positive electrode sheets, a separator and a negative electrode sheet, and the electrode assembly is a laminated electrode assembly; The length of the packaging bag is ≥400mm; A storage space is provided in the packaging bag, the storage space being provided at the gap between the packaging bag and the electrode assembly, and the storage space being used to store electrolyte; At least one surface of the isolation film is provided with an adhesive layer, and the adhesive layer includes a plurality of adhesive-coated areas and a plurality of non-adhesive-coated areas.

2. The battery cell according to claim 1, wherein: The non-glue-coated area is in a strip-shaped structure.

3. The battery cell according to claim 2, characterized in that: The width of the non-glue-coated area is 0.5 mm to 3 mm.

4. The battery cell according to claim 2, characterized in that The width of the non-glue-coated area is 0.5 mm to 1.5 mm.

5. The battery cell according to claim 2, characterized in that: The width of the glue-coated area is 3 mm to 6 mm.

6. The battery cell according to any one of claims 2 to 5, characterized in that: The glue-coated area is in a strip-shaped structure, and a plurality of glue-coated areas with strip-shaped structures are arranged in parallel along the length direction of the isolation film. The gaps between adjacent glue-coated areas in the strip-shaped structure serve as the non-glue-coated area.

7. The battery cell according to claim 6, characterized in that The included angle between the length direction of the non-glue-coated area and the length direction of the isolation film is 30° to 75°.

8. The battery cell according to claim 6, characterized in that The included angle between the length direction of the non-glue-coated area and the length direction of the isolation film is 35° to 65°.

9. The battery cell according to claim 1, characterized in that The ratio of the area of the non-glue-coated area to the area of the glue-coated area is (1-5):

6.

10. The battery cell according to claim 1, characterized in that The ratio of the area of the non-glue-coated area to the area of the glue-coated area is (1-4):

6.

11. The battery cell according to claim 1, characterized in that Located at any one end of the packaging bag in the length direction, a gap formed between the end of the packaging bag and the end of the electrode assembly along the length direction of the packaging bag serves as the storage space.

12. The battery cell according to claim 11, characterized in that Located at any end of the length direction of the packaging bag, and along the length direction of the packaging bag, the shortest straight-line distance between the end of the packaging bag and the end of the electrode assembly is 12 mm to 18 mm.

13. The battery cell according to claim 1, characterized in that The length of the packaging bag is 400mm~700mm.

14. The battery cell according to claim 1, characterized in that The positive electrode sheet includes a positive electrode current collector and a positive electrode active film layer located on at least one side of the positive electrode current collector; the negative electrode sheet includes a negative electrode current collector and a negative electrode active film layer located on at least one side of the negative electrode current collector.

15. The battery cell according to claim 14, characterized in that The compaction density of the positive electrode active film layer is 2.3 g / cm 3 ~2.47g / cm 3 , and / or, the compaction density of the negative electrode active film layer is 1.4 g / cm 3 ~1.55g / cm 3 .

16. The battery cell according to claim 14 or 15, characterized in that: The porosity of the positive electrode active film layer is 23% to 30%, and / or the porosity of the negative electrode active film layer is 22% to 29%.

17. The battery cell according to claim 14, characterized in that The positive electrode active film layer contains a positive electrode active material, and the positive electrode active material includes lithium iron phosphate; and / or the negative electrode active film layer contains a negative electrode active material, and the negative electrode active material includes graphite.

18. The battery cell according to claim 1, characterized in that The battery cell also includes an electrolyte, the viscosity of which is 1.0 mm 2 / s~2.6mm 2 / s.

19. A battery device, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 18.

20. An energy storage device, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 18, or a battery device according to claim 19.

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