Single battery and battery pack

Abstract

The utility model discloses a single battery and a battery pack. The single battery comprises a shell, a battery cell and a plurality of insulating connecting pieces, the battery cell is accommodated in the shell, the battery cell comprises pole piece layers and diaphragm layers, the diaphragm layers are arranged between the adjacent pole piece layers, and the polarities of the adjacent pole piece layers are opposite; one end of at least part of the insulating connecting piece is embedded into the diaphragm layer, and the other end of the insulating connecting piece is embedded into the pole piece layer attached to one side of the diaphragm layer. The two ends of the insulating connecting piece are respectively embedded into the pole piece layer and the diaphragm layer, so that the connection between the pole piece layer and the diaphragm layer can be reinforced, and the risks of short circuit and thermal runaway of the single battery are reduced; the expansion thickness change of the battery cell is reduced, and the volume energy density of the single battery is favorably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of secondary batteries, in particular to a single battery and a battery pack. BACKGROUND

[0002] In the prior art, a cell is formed by laminating or winding a positive plate, a separator and a negative plate. Due to factors such as the material of the separator, the longitudinal shrinkage rate of the separator, the thickness inconsistency of the positive and negative plates, and the expansion of the plates during charging, the positive and negative plates and the separator are prone to not being tightly attached in the thickness direction of the separator. In addition, under the influence of external factors, the stress area of the cell is prone to not being tightly attached, which affects the capacity, cycle life and safety of the battery.

[0003] Therefore, it is necessary to improve the prior art. CONTENT OF THE UTILITY MODEL

[0004] The utility model aims at solving at least one of the technical problems existing in the prior art, and provides a single battery and a battery pack.

[0005] According to an aspect of the present application, the present application provides a single battery, which comprises a shell, a cell and a plurality of insulating connecting pieces. The cell is accommodated in the shell, and the cell comprises a plurality of plate layers and a separator layer. The separator layer is arranged between adjacent plate layers, and the polarities of adjacent plate layers are opposite. At least part of the insulating connecting pieces is embedded in one end of the separator layer and the other end of the plate layer attached to one side of the separator layer.

[0006] Further, the plate layer comprises a positive plate layer and a negative plate layer, and the separator layer is arranged between the positive plate layer and the negative plate layer. Part of the insulating connecting pieces is embedded in one end of the separator layer and the other end of the positive plate layer. And / or, part of the insulating connecting pieces is embedded in one end of the separator layer and the other end of the negative plate layer.

[0007] Optionally, the plate layer comprises a current collector and an active layer. In the thickness direction of the current collector, the active layer is arranged on at least one side of the current collector. In the same plate layer, part of the insulating connecting pieces is embedded in one end of the current collector and the other end of the active layer.

[0008] Further, the plate layer comprises a current collector.

[0009] In the plurality of insulating connecting pieces, at least one insulating connecting piece is embedded in one end of the current collector and the other end of the separator layer adjacent to the current collector.

[0010] Further, the plate layer further comprises an active layer. In the thickness direction of the current collector, the active layer is arranged on at least one side of the current collector.

[0011] At least one of the plurality of insulation connectors has one end embedded in the current collector and the other end embedded in the active layer and the separator layer.

[0012] Further, the separator layer comprises a substrate layer and a coating layer, the coating layer is arranged on at least one side of the substrate layer in the thickness direction of the substrate layer, and one end of a part of the insulation connectors is embedded in the substrate layer and the other end is embedded in the coating layer in the same separator layer.

[0013] Further, the insulation connectors extend in the thickness direction of the pole piece layer.

[0014] Further, the battery cell is a jelly-roll battery cell, the battery cell has a flat portion and two curved portions, the two curved portions are respectively located on the opposite sides of the flat portion; the insulation connectors comprise first connecting nails and second connecting nails, the first connecting nails are arranged on the curved portions, and the second connecting nails are arranged on the flat portion; the battery cell, when unfolded to a flat state, has a first direction and a second direction intersecting with each other; in the first direction, the battery cell unfolded to the flat state has first regions and second regions arranged alternately, the first connecting nails are arranged in the first regions, and the second connecting nails are arranged in the second regions; in the first direction and the second direction, the size of the first connecting nails is smaller than the size of the second connecting nails.

[0015] Further, the number of the first connecting nails is greater than the number of the second connecting nails.

[0016] And / or, the distribution number of the first connecting nails per unit volume in the first regions is greater than the distribution number of the second connecting nails per unit volume in the second regions.

[0017] Further, in the battery cell unfolded to the flat state, the distance between adjacent insulation connectors in the first direction is d1 mm, the size of the second regions in the first direction is L mm, and 0 < d1 / L < 0.5 is satisfied; the distance between adjacent insulation connectors in the second direction is d2 mm, the size of the second regions in the second direction is W mm, and 0 < d2 / W < 0.5 is satisfied.

[0018] Further, in the thickness direction of the pole piece layer, the size of the insulation connectors is H μm, the thickness of the pole piece layer is h1 μm, and the thickness of the separator layer 22 is h2 μm, and 0 < H < h1+h2 is satisfied.

[0019] According to another aspect of the present application, a battery pack is provided, comprising the single battery cell according to any one of the preceding aspects.

[0020] The application has the beneficial effects that the application can reinforce the connection between the pole piece layer and the diaphragm layer, reduce the possibility of delamination of the pole piece layer and the diaphragm layer, and reduce the risk of short circuit and thermal runaway of the single battery by embedding the two ends of the insulating connecting piece into the pole piece layer and the diaphragm layer respectively. At the same time, the setting of the insulating connecting piece reduces the expansion thickness change of the battery cell, which is beneficial to the improvement of the volume energy density of the single battery. BRIEF DESCRIPTION OF DRAWINGS

[0021] The technical solutions and other beneficial effects of the application will be apparent from the following detailed description of the specific embodiments of the application in conjunction with the accompanying drawings.

[0022] Figure 1 is a partial cross-sectional view of a battery cell provided by an embodiment of the application;

[0023] Figure 2 is a schematic view of a single battery provided by an embodiment of the application;

[0024] Figure 3 is a schematic view of a battery cell provided by an embodiment of the application;

[0025] Figure 4 is a schematic view of another battery cell provided by an embodiment of the application;

[0026] Figure 5 is a schematic view of a battery cell winding provided by an embodiment of the application;

[0027] Figure 6 is a schematic view of the arrangement of an insulating connecting piece provided by an embodiment of the application;

[0028] Figure 7 is a schematic view of the diaphragm layer being unfolded to a flat state provided by an embodiment of the application;

[0029] In the drawings:

[0030] 10, housing;

[0031] 20, battery cell; 201, flat part; 202, curved part; 21, pole piece layer; 211, positive pole piece layer; 212, negative pole piece layer; 213, current collector; 214, active layer; 22, diaphragm layer; 221, base material layer; 222, coating layer; 223, first region; 224, second region;

[0032] 30, insulating connecting piece; 31, first connecting nail; 32, second connecting nail. DETAILED DESCRIPTION

[0033] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0034] In the description of the present application, it should be noted that unless specifically defined and limited, the terms "mounting", "connection", "connecting" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or the internal connection of two elements or the interaction relationship between two elements. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] As a prologue of the embodiments of the present application, the positive plate, the separator and the negative plate are laminated or wound to form the battery cell, and due to the influence of factors such as the material of the separator, the longitudinal shrinkage rate of the separator, the thickness inconsistency of the positive and negative plates, and the expansion of the plates during charging, the positive and negative plates and the separator are more likely to appear not tightly fitted in the thickness direction of the separator; in addition, under the influence of external factors, the stress area of the battery cell is more likely to appear not tightly fitted, which affects the capacity, cycle life and safety of the battery.

[0036] At the same time, the secondary battery will expand when in use, and after expansion, expansion force will be generated. In order to ensure the safety of the structural members in the battery module, the gap between adjacent secondary batteries needs to be increased to reserve a large enough expansion gap. However, the above technical means has low utilization rate of the internal space of the battery module, resulting in low volume capacity density of the battery.

[0037] In order to solve the problem of not tightly fitted between the internal layers of the battery cell and easy to appear delamination in the prior art, an embodiment of the present application provides a single battery, which comprises a shell, a battery cell and a plurality of insulating connecting pieces; the battery cell is accommodated in the shell, the battery cell comprises a plate layer and a separator layer, the separator layer is arranged between adjacent plate layers, and the adjacent plate layers have opposite polarities; one end of at least part of the insulating connecting pieces is embedded in the separator layer, and the other end is embedded in the plate layer which is attached to one side of the separator layer. The following will be described in detail.

[0038] Referring to Figure 1 and Figure 2In an embodiment, the monomer battery includes a shell 10, an electric core 20 arranged inside the shell 10, and a plurality of insulating connecting pieces 30. The electric core 20 includes a plurality of pole piece layers 21 and a diaphragm layer 22 arranged between two adjacent pole piece layers 21, and the pole piece layers 21 on both sides of the diaphragm layer 22 have opposite polarities. In this embodiment, one end of at least part of the insulating connecting pieces 30 is embedded in the diaphragm layer 22, and the other end is embedded in the pole piece layer 21 adhered to one side of the diaphragm layer 22. The insulating connecting pieces 30 can reinforce the adhesion between the diaphragm layer 22 and the pole piece layer 21, so that the adhesion between them is tighter, reducing the risk of short circuit and thermal runaway of the monomer battery, effectively improving the service life of the monomer battery, and inhibiting the change in the thickness of the electric core 20 caused by expansion during charging and discharging, which is beneficial to the improvement of the volume energy density of the monomer battery.

[0039] It should be noted that the monomer battery includes but is not limited to lithium ion secondary battery, sodium lithium ion battery, sodium ion battery or magnesium ion battery, etc., and the present embodiment does not limit this; the diaphragm layer 22 is arranged between the adjacent pole piece layers 21 to prevent the short circuit of the pole piece layers 21 with opposite polarities on both sides of the diaphragm layer 22, and the pole piece layer 21 and the diaphragm layer 22 are formed into the electric core 20 through a conventional winding process (as shown in Figure 4 ), or the pole piece layer 21 and the diaphragm layer 22 are formed into the electric core 20 through a conventional laminating process (as shown in Figure 3 ). At the same time, the insulating connecting pieces 30 can be nano-level micro-nails, such as nanowires, which are struck at suitable positions of the adhesion interface between the pole piece layer 21 and the diaphragm layer 22 by means of femtosecond laser, deposition method, etc. The material of the nanowires can be SiO2, TiO2, etc. insulating material to avoid short circuit and effectively improve the use safety of the monomer battery.

[0040] Please continue to refer to Figure 1 In an embodiment, the pole piece layer 21 includes a positive pole piece layer 211 and a negative pole piece layer 212, and the diaphragm layer 22 is arranged between the positive pole piece layer 211 and the negative pole piece layer 212 (as shown in Figure 5 ). In this embodiment, one end of the insulating connecting piece 30 is embedded in the positive pole piece layer 211, and the other end is embedded in the diaphragm layer 22, which can reinforce the adhesion between the positive pole piece layer 211 and the diaphragm layer 22, so that the adhesion between them is tighter, avoiding the contact between the local positive pole piece layer 211 and the negative pole piece layer 212 caused by the shrinkage of the diaphragm layer 22, and improving the use safety of the monomer battery.

[0041] It should be noted that in some embodiments, the above-mentioned insulating connecting piece 30 can also be embedded into the above-mentioned negative electrode sheet layer 212 at one end and into the separator layer 22 at the other end; or both the insulating connecting piece 30 embedded into the positive electrode sheet layer 211 at one end and into the separator layer 22 at the other end and the insulating connecting piece 30 embedded into the negative electrode sheet layer 212 at one end and into the separator layer 22 at the other end exist at the same time, which will not be described here.

[0042] Continuing to refer to Figure 1 In an embodiment, the above-mentioned sheet layer 21 includes a current collector 213 and an active layer 214, and the above-mentioned active layer 214 is arranged on both sides of the above-mentioned current collector 213 in the thickness direction of the above-mentioned current collector 213; at least one of the above-mentioned insulating connecting pieces 30 is used to connect the above-mentioned current collector 213 and the above-mentioned active layer 214, and one end of the above-mentioned insulating connecting piece 30 is embedded into the above-mentioned current collector 213 and the other end is embedded into the above-mentioned active layer 214, which strengthens the connection between the active layer 214 and the above-mentioned current collector 213 and ensures that the two are tightly attached, effectively improving the conductive capacity.

[0043] It should be noted that in some embodiments, the above-mentioned active layer 214 can be arranged on one side of the above-mentioned current collector 213 in the thickness direction thereof, which will not be described here; in some embodiments, the above-mentioned current collector 213 and the above-mentioned active layer 214 can be connected by metal nanowires, such as N, Pt, etc., which can effectively improve the conductive capacity between the current collector 213 and the active layer 214, but may cause short circuit of the metal nanowires, so the present embodiment focuses on insulating nanowires. In the actual production process, the above-mentioned insulating connecting piece 30 can be embedded into the above-mentioned current collector 213 before the above-mentioned active layer 214 is coated onto the above-mentioned current collector 213, and then the coating step of the active layer 214 is performed, so that the embedded insulating connecting piece 30 is formed between the current collector 213 and the active layer 214.

[0044] In an embodiment, the pole piece layer 21 comprises a current collector 213; and at least one of the plurality of insulation connectors 30 has one end embedded in the current collector 213 and the other end embedded in the diaphragm layer 22 adjacent to the current collector 213. Specifically, the pole piece layer 21 further comprises an active layer 214, which is arranged at least on one side of the current collector 213; and at least one of the plurality of insulation connectors 30 has a portion embedded in the active layer 214 adjacent to the current collector 213. When the active layer 214 is arranged between the current collector 213 and the diaphragm layer 22, at least one of the insulation connectors 30 has one end embedded in the current collector 213 and the other end embedded in the diaphragm layer 22 through the active layer 214 on the surface of the current collector 213, so that the connection between the current collector 213 and the active layer 214 and the connection between the active layer 214 and the diaphragm layer 22 can be reinforced by one insulation connector 30, and the current collector 213 and the active layer 214 and the diaphragm layer 22 can be closely attached. In actual production, the insulation connector 30 can be embedded in the current collector 213 before the active layer 214 is coated on the current collector 213, and then the coating step of the active layer 214 is performed. After the coating of the active layer 214 is completed, the insulation connector 30 penetrates through the active layer 214, and then the diaphragm layer 22 is wound or stacked on the pole piece layer 21 (active layer 214), so that the insulation connector 30 is embedded in the diaphragm layer 22, and the same insulation connector 30 is embedded in the current collector 213, the active layer 214 and the diaphragm layer 22.

[0045] In addition, in an embodiment, one end of the insulation connector 30 is embedded in the active layer 214 and the other end is embedded in the diaphragm layer 22. In this embodiment, the insulation connector 30 needs to be embedded in the diaphragm layer 22 in the thickness direction of the diaphragm layer 22, and the size of the insulation connector 30 is relatively small, so that the active layer 214 and the diaphragm layer 22 (the pole piece layer 21 and the diaphragm layer 22) can be reinforced by the insulation connector 30 with a small size, and the active layer 214 and the diaphragm layer 22 can be closely attached while the production cost is reduced. The shorter the size of the insulation connector 30 in the thickness direction of the diaphragm layer 22, the lower the cost. Details are not described here.

[0046] Continuing to refer to Figure 1 In an embodiment, the diaphragm layer 22 comprises a substrate layer 221 and a coating layer 222, and the coating layer 222 is arranged on one side of the substrate layer 221 in the thickness direction of the substrate layer 221. In some embodiments, the coating layer 222 can be arranged on both sides of the substrate layer 221, but is not limited thereto. In the same diaphragm layer 22, one end of the insulation connector 30 is embedded in the substrate layer 221 and the other end is embedded in the coating layer 222, so as to reinforce the connection between the substrate layer 221 and the coating layer 222.

[0047] It should be noted that in some embodiments, the portion of the insulating connector 30 embedded in the separator layer 22 may be embedded in the coating 222, or it may be embedded in the substrate layer 221 after passing through the coating 222 on the surface of the substrate layer 221. This will not be elaborated further and will be determined based on actual production needs. The more insulating connectors 30 are provided, the higher the cost. Insulating connectors 30 can be provided between adjacent layers requiring reinforcement, according to the actual design requirements of the cell 20. Simultaneously, to effectively improve the tightness of the adhesion between layers, the insulating connectors 30 extend along the thickness direction of the electrode layer 21, that is, the insulating connectors 30 are set perpendicular to the electrode layer 21 and the separator layer 22. This arrangement can reduce the expansion of the cell 20 (better contact between layers), effectively improving rate performance. Furthermore, the smaller expansion of the cell 20 can reduce the fatigue of the electrode layer 21, effectively increasing its service life.

[0048] See Figure 5 and Figure 6 In one embodiment, the battery cell 20 is a wound core, having a flat portion 201 and two bent portions 202, the two bent portions 202 being respectively disposed on opposite sides of the flat portion 201; the insulating connector 30 includes a first connecting pin 31 and a second connecting pin 32, the first connecting pin 31 being disposed on the bent portion 202, and the second connecting pin 32 being disposed on the flat portion 201; the battery cell 20 is in a flat state (e.g. Figure 7 As shown), having intersecting first directions ( Figure 7 (As shown in the middle direction X, the same below) and the second direction ( Figure 7 (As shown in the Y direction, the same below), in the first direction, the battery cell 20 unfolded to a flat state has alternating first region 223 and second region 224. The first connecting pin 31 is disposed in the first region 223, and the second connecting pin 32 is disposed in the second region 224. In both the first and second directions, the size of the first connecting pin 31 is smaller than the size of the second connecting pin 32. It can be understood that the size of the first connecting pin 31 and the second connecting pin 32 can be the diameter, that is, the diameter of the first connecting pin 31 is smaller than the diameter of the second connecting pin 32. The size of the first connecting pin 31 and the second connecting pin 32 can also include the length, that is, the length of the first connecting pin 31 is smaller than the length of the second connecting pin 32.

[0049] In some embodiments, the number of first connecting studs 31 per unit volume in the first region 223 is greater than the number of second connecting studs 32 per unit volume in the second region 224. By arranging more first connecting studs 31 in the first region 223, the reinforcement effect of the bend 202 is improved, and the connection tightness between adjacent layers is increased.

[0050] In the embodiment, the first connecting nail 31 and the second connecting nail 32 are in a columnar shape, that is, the diameter of the first connecting nail 31 is smaller than that of the second connecting nail 32, and in some embodiments, the first connecting nail 31 and the second connecting nail 32 can also be arranged in other forms, which are not limited to this; after the diaphragm layer 22 and the pole piece layer 21 are wound into a roll core, the surface of the curved portion 202 is curved, and the small diameter of the first connecting nail 31 can ensure that the diaphragm layer 22 and the pole piece layer 21 of the curved portion 202 are connected tightly, the second connecting nail 32 is arranged on the flat portion 201, and the surface of the flat portion 201 is a plane, which is conducive to the embedding of the second connecting nail 32, so that the second connecting nail 32 with a larger diameter than the first connecting nail 31 can be arranged to reduce the production cost. The smaller the diameter of the insulating connecting piece 30, the more difficult the processing is, and the higher the production cost is; in actual use, the diaphragm layer 22 and the pole piece layer 21 of the curved portion 202 are more likely to have a gap (delamination), so a large number of first connecting nails 31 can be arranged on the curved portion 202 to further reinforce the connection between the diaphragm layer 22 and the pole piece layer 21. The arrangement of the first connecting nail 31 with a small diameter can also provide space for embedding a larger number of first connecting nails 31 in the curved portion 202 to improve the reinforcing effect.

[0051] It should be noted that in some embodiments, the first connecting nail 31 and the second connecting nail 32 can be arranged regularly, or the first connecting nail 31 and the second connecting nail 32 can be arranged at corresponding positions according to actual design requirements of the battery cell 20, which will not be described here.

[0052] In addition, when the battery cell 20 is formed by the pole piece layer 21 and the diaphragm layer 22 through a lamination process, the edge of the battery cell 20 is more likely to delaminate under external force; therefore, a large number of insulating connecting pieces 30 can be arranged on the periphery of the diaphragm layer 22 to reinforce the connection between the diaphragm layer 22 and the pole piece layer 21, which will not be described here.

[0053] Continuing to refer to Figure 1 In an embodiment, in the thickness direction of the pole piece layer 21, the size of the insulating connecting piece 30 is H μm, the thickness of the pole piece layer 21 is h1 μm, and the thickness of the diaphragm layer 22 is h2 μm, which satisfies: 0 < H < h1 + h2, that is, the size of the insulating connecting piece 30 is smaller than the sum of the thicknesses of the pole piece layer 21 and the diaphragm layer 22. In this way, the risk of short circuit caused by the insulating connecting piece 30 piercing the diaphragm layer 22 due to the excessive size of the insulating connecting piece 30 in the thickness direction of the pole piece layer 21 can be effectively reduced to a certain extent, and the safety of the single battery is further improved through size limitation.

[0054] It needs to be understood that the insulation connector 30 has an upper embedding amount H1 mm and a lower embedding amount H2 mm (only one of the upper embedding amount and the lower embedding amount can exist), which satisfy 0<H1<h1+h2 and 0<H2<h1+h2; wherein H1 is generally between 10 um and 500 um, and H2 is generally also between 10 um and 500 um; it needs to be understood that the upper embedding amount and the lower embedding amount refer to, taking any side of the diaphragm layer 22 connected with the pole piece layer 21 as an interface, a size of one end of the insulation connector 30 from the interface as the upper embedding amount, and a size of the other end of the insulation connector 30 from the interface as the lower embedding amount.

[0055] It needs to be noted that in some embodiments, the size of the insulation connector 30 in the thickness direction of the pole piece can be set to be very large, for example, one end of the insulation connector 30 is embedded in the positive pole piece layer 211, the other end penetrates through the diaphragm layer 22 attached to one side of the positive pole piece layer 211 and is embedded in the negative pole piece layer 212 on the other side of the diaphragm layer 22, in this way, although the connection between multiple adjacent layers can be realized by one insulation connector 30, in order to ensure the safe use of the single battery without short circuit, the diameter of the insulation connector 30 needs to be set to be very small to avoid the contact between the positive active material and the negative active material, and the production cost is relatively high, which will not be described here.

[0056] In an embodiment, when the battery cell 20 is unfolded to a flat state, the distance between adjacent insulation connectors 30 on the same diaphragm layer 22 in the first direction is d1 mm, and the size of the second area 224 in the first direction is L mm, which satisfy 0<d1 / L<0.5. Specifically, d1 / L can be any value in 0.1 / 0.2 / 0.3 / 0.4 or a range value between any two values. In the range of 0 to 0.5 (not including the end point value), the larger d1 / L is, the smaller the density of the insulation connector 30 is, and the tightness of the connection between multiple adjacent layers gradually decreases.

[0057] The distance between adjacent insulation connectors 30 in the second direction is d2 mm, and the size of the second area 224 in the second direction is W mm, which satisfy 0<d2 / W<0.5. Specifically, d2 / W can be any value in 0.1 / 0.2 / 0.3 / 0.4 or a range value between any two values. In the range of 0 to 0.5 (not including the end point value), the larger d2 / W is, the smaller the density of the insulation connector 30 is, and the tightness of the connection between multiple adjacent layers gradually decreases.

[0058] In this way, by reasonably setting the distance between adjacent insulation connectors 30, the embodiment can ensure the tightness of the connection between adjacent layers, effectively improve the electrical performance and service life of the single battery, and improve the volume energy density.

[0059] The technical solutions provided by the embodiments of the present application are evaluated below in combination with specific embodiments. Among them, the volumetric energy density = secondary battery energy / secondary battery volume = capacity* voltage / (length* width* height of the secondary battery), the swelling thickness refers to the thickness of the secondary battery after disassembly after cycling, wherein the cycling refers to 1C full charging, 1C full discharging 1000 times of the secondary battery under the condition of 45°C±5°C. Generally, the size parameters appearing in the embodiments of the present application can be measured by using vernier caliper, micrometer and the like, or the size parameters in the embodiments of the present application can be obtained directly by projection measurement method, or the size parameters in the embodiments of the present application can be obtained by image processing method using image software, and the secondary battery volume parameter is obtained by measuring the length, width and height of the secondary battery and calculating by using geometric formula; the capacity and voltage of the secondary battery can be measured respectively, and then the energy is obtained by multiplying the capacity and voltage of the secondary battery; wherein the capacity of the secondary battery is calculated by using constant current discharging method, and a multimeter or a digital voltmeter and the like is connected to the positive and negative electrodes of the secondary battery to measure the voltage of the secondary battery. In addition, other conventional measurement methods can also be used to obtain the above parameters, which will not be described here.

[0060] It should be understood that in the following embodiments, 10 secondary batteries are used for testing in each group of embodiments to obtain the volumetric energy density interval value, and the swelling thickness increase represents the average increase in thickness of the 10 secondary batteries after disassembly under free state after cycling. In addition, the battery system used in the embodiments of the present application is "lithium iron phosphate-graphite battery".

[0061] The test results of the embodiments are as follows:

[0062] d1 / mm L / mm d1 / L d2 / mm W / mm d2 / W Swelling thickness increase / mm Example 1 20 200 0.1 30 100 0.3 0.6 Example 2 40 200 0.2 30 100 0.3 0.9 Example 3 60 200 0.3 30 100 0.3 1.2 Example 4 80 200 0.4 30 100 0.3 1.5 Example 5 100 200 0.5 30 100 0.3 1.8 Example 6 60 200 0.3 10 100 0.1 0.6 Example 7 60 200 0.3 20 100 0.2 0.9 Example 8 60 200 0.3 30 100 0.3 1.2 Example 9 60 200 0.3 40 100 0.4 1.5 Example 10 60 200 0.3 50 100 0.5 1.8

[0063] As shown in the above table, in the embodiments 1 to 5, d1 / L is controlled in the range of 0 to 0.5, when d1 / L is closer to 0, it means that the distance of adjacent insulation connectors 30 in the first direction X is smaller, which can indicate that the arrangement density of the insulation connectors 30 in the second area 224 is larger, and the effect of inhibiting the swelling of the secondary battery is better; when d1 / L is closer to 0.5, it means that the distance of adjacent insulation connectors 30 in the first direction X is larger, which can indicate that the arrangement density of the insulation connectors 30 in the second area 224 is smaller, and the effect of inhibiting the swelling of the secondary battery decreases;

[0064] Similarly, in Embodiments 6-10, d2 / W is controlled in the range of 0-0.5, when d2 / W is closer to 0, it means that the distance between adjacent insulation connectors 30 in the first direction X is smaller, which means that the arrangement density of the insulation connectors 30 in the second area 224 is larger, and the effect of inhibiting the swelling of the secondary battery is better; when d2 / W is closer to 0.5, it means that the distance between adjacent insulation connectors 30 in the first direction X is larger, which means that the arrangement density of the insulation connectors 30 in the second area 224 is smaller, and the effect of inhibiting the swelling of the secondary battery is reduced; in the above Embodiments 1-8, the volumetric energy density of the secondary battery is between 370-400 Wh / L, and the smaller the arrangement density of the insulation connectors 30, the larger the volumetric energy density of the secondary battery.

[0065] The present application improves the adhesion performance of the interface between the separator layer 22 and the pole piece layer 21 by adding the insulation connector 30, regardless of the expansion stress, external mechanical stress (extrusion, impact, etc.), which greatly reduces the possibility of interface delamination, ensures the smoothness of the lithium ion and electron transmission path, improves the electrical performance and service life, and at the same time, the insulation connector 30 has the effect of reducing the swelling force of the secondary battery, reducing the gap between the pole piece layer 21, and improving the volumetric energy density of the secondary battery.

[0066] Specifically, under the action of external mechanical force (extrusion, impact), due to the interface treatment, the interface increases the mechanical connection and improves the interface strength, the possibility of secondary battery delamination is reduced, therefore, the probability of ion and electron transmission path blockage is reduced, the risk of separator shrinkage is also reduced, and thus the risk of short circuit and thermal runaway is reduced.

[0067] It is considered that in different designs of the secondary battery, when the separator layer 22 is prone to wrinkling, the insulation connector 30 is added between the separator layer 22 and the pole piece layer 21, and when the separator layer 22 is a multi-layer structure, the insulation connector 30 can be added between the multi-layer structure in the separator layer 22. If the current collector 213 and the active layer 214 are prone to delamination, the insulation connector 30 needs to be added between the current collector 213 and the active layer 214. As described above, the design position of the insulation connector 30 can be selected according to the needs, which will not be described here.

[0068] It should be noted that when the secondary battery is made of a laminated structure, the insulation connector 30 still has the above technical effects, which will not be described here.

[0069] The above has carried on the detailed introduction to the single battery and the battery pack provided by the embodiment of the application, the principle and the implementation mode of the application are described in the text by applying specific examples; the above embodiment description is only used for helping understanding the application and its core idea; meanwhile, for the general technical personnel in the art, according to the idea of the application, the specific implementation mode and the application range will have the change, and the above is described, and the content of the specification should not be understood as the limitation of the application.

Claims

1. A single cell, characterized by, The single battery comprises: a housing (10); a cell (20) accommodated in the housing (10), the cell (20) comprising a plurality of electrode sheet layers (21) and separator layers (22), the separator layers (22) being arranged between adjacent electrode sheet layers (21) and having opposite polarities to the adjacent electrode sheet layers (21); and a plurality of insulating connecting members (30), at least part of the insulating connecting members (30) being embedded in the separator layers (22) at one end and in the electrode sheet layers (21) adjacent to the separator layers (22) at the other end.

2. The single battery according to claim 1, wherein the electrode sheet layers (21) comprise positive electrode sheet layers (211) and negative electrode sheet layers (212), and the separator layers (22) are arranged between the positive electrode sheet layers (211) and the negative electrode sheet layers (212); part of the insulating connecting members (30) are embedded in the separator layers (22) at one end and in the positive electrode sheet layers (211) at the other end; and / or part of the insulating connecting members (30) are embedded in the separator layers (22) at one end and in the negative electrode sheet layers (212) at the other end.

3. The single battery according to claim 1, wherein the electrode sheet layers (21) comprise current collectors (213) and active layers (214), and the active layers (214) are arranged on at least one side of the current collectors (213) in the thickness direction of the current collectors (213); in the same electrode sheet layers (21), part of the insulating connecting members (30) are embedded in the current collectors (213) at one end and in the active layers (214) at the other end.

4. The single battery according to claim 1, wherein the electrode sheet layers (21) comprise current collectors (213); in the plurality of insulating connecting members (30), at least one insulating connecting member (30) is embedded in the current collectors (213) at one end and in the separator layers adjacent to the current collectors (213) at the other end.

5. The single battery according to claim 4, wherein the electrode sheet layers (21) further comprise active layers (214), and the active layers (214) are arranged on at least one side of the current collectors (213) in the thickness direction of the current collectors (213); in the plurality of insulating connecting members (30), at least one insulating connecting member (30) is embedded in the current collectors (213) at one end and penetrates the active layers (214) and is embedded in the separator layers at the other end.

6. The single battery according to claim 1, wherein the separator layers (22) comprise base material layers (221) and coating layers (222), and the coating layers (222) are arranged on at least one side of the base material layers (221) in the thickness direction of the base material layers (221), and in the same separator layers (22), part of the insulating connecting members (30) are embedded in the base material layers (221) at one end and in the coating layers (222) at the other end.

7. The single battery according to any one of claims 1 to 6, wherein ​ The insulating connecting piece (30) extends along the thickness direction of the pole piece layer (21). 8.The single battery of claim 1, wherein, The electric core (20) is a roll core, and the electric core (20) has a flat portion (201) and two curved portions (202) respectively located on opposite sides of the flat portion (201); The insulating connecting piece (30) includes a first connecting nail (31) and a second connecting nail (32), the first connecting nail (31) is arranged on the curved portion (202), and the second connecting nail (32) is arranged on the flat portion (201); The electric core (20) has a first direction (X) and a second direction (Y) intersecting when the electric core (20) is unfolded to a flat state; In the first direction (X), the electric core (20) unfolded to the flat state has first regions (223) and second regions (224) arranged alternately, the first connecting nail (31) is arranged on the first region (223), and the second connecting nail (32) is arranged on the second region (224); In the first direction (X) and the second direction (Y), the size of the first connecting nail (31) is smaller than the size of the second connecting nail (32). 9.The single battery of claim 8, wherein, The number of the first connecting nail (31) is greater than the number of the second connecting nail (32); And / or, the distribution number of the first connecting nail (31) in a unit volume in the first region (223) is greater than the distribution number of the second connecting nail (32) in a unit volume in the second region (224). 10.The single battery of claim 8, wherein, In the electric core (20) unfolded to the flat state, the distance between adjacent insulating connecting pieces (30) in the first direction (X) is d1 mm, the size of the second region (224) in the first direction (X) is L mm, and 0 < d1 / L < 0.5 is satisfied, the distance between adjacent insulating connecting pieces (30) in the second direction (Y) is d2 mm, the size of the second region (224) in the second direction (Y) is W mm, and 0 < d2 / W < 0.5 is satisfied. 11.The single battery of claim 1, wherein, In the thickness direction of the pole piece layer (21), the size of the insulating connecting piece (30) is H μm, the thickness of the pole piece layer (21) is h1 μm, and the thickness of the diaphragm layer (22) is h2 μm, and 0 < H < h1+h2 is satisfied.

12. A battery pack, characterized by A single battery as claimed in any one of claims 1 to 11.

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