Single cell, battery pack, and electric device

Abstract

The utility model relates to battery manufacturing technology field especially, it relates to a single battery, battery group and electric equipment, single battery includes electrode assembly, including the winding or stacking setting positive plate, diaphragm and negative plate, diaphragm is located between adjacent positive plate and negative plate, electrode assembly has the outside surface formed by diaphragm, positive plate and negative plate all have the end part close to outside surface, the end part extends along the winding direction and is cut to form the end, the end of negative plate exceeds the end of positive plate along the winding direction, the end part of positive plate pastes positive tape, and positive tape at least covers the end of positive plate, the end part of negative plate pastes negative tape, and negative tape at least covers the end of negative plate, and the heat resistance of positive tape is higher than the heat resistance of negative tape. The utility model through the differential treatment to positive tape and negative tape to adapt to its particular needs, guarantee the characteristics of positive tape and negative tape to meet the use requirement, prevent thermal failure and mechanical failure to ensure the stability and security of electric core.

Description

Technical Field

[0001] This utility model relates to the field of battery manufacturing technology, and in particular to a single cell, a battery pack, and an electrical device. Background Technology

[0002] The electrode assembly of a secondary battery comprises an electrode structure formed by winding or stacking positive and negative electrodes and a separator between them. The design and process control of the terminal sections (i.e., the ends of the positive, negative, and separator electrodes) are crucial, affecting not only battery assembly, capacity, and energy density, but also core performance characteristics such as long-term cell safety and cycle life. At the cutting points of the positive and negative electrodes, sharp edges or burrs can easily form during the cutting process, leading to high stress concentration at these locations. There is also a risk that metal burrs may puncture the separator, causing a short circuit due to direct contact between the positive and negative electrodes.

[0003] Cutting tape is typically applied at the cut points of the positive and negative electrode sheets to prevent burrs, metal shavings, and other issues. The tensile strength of the tape's substrate can suppress subsequent tearing, and its elastic modulus can absorb end stress on the electrode sheets, reducing coating peeling caused by stress concentration. However, when the active materials coated on the positive and negative electrode sheets differ significantly, the differences in the heat resistance and expansion properties of the cutting tape are often overlooked, leading to abnormal stress distribution, decreased dimensional stability, and reduced adhesion yield. Utility Model Content

[0004] This utility model provides a single battery, a battery pack, and an electrical device to solve the technical problem in the prior art that, when there are significant differences in the active material and current collector materials coated on the positive and negative electrodes, there is often a lack of consideration for the differences in the cutting tape.

[0005] This utility model provides a single battery cell, which includes an electrode assembly, comprising a positive electrode sheet, a separator, and a negative electrode sheet wound or stacked, wherein the separator is located between adjacent positive and negative electrode sheets.

[0006] The electrode assembly has an outer surface formed by the diaphragm. Both the positive electrode and the negative electrode have a tapered portion near the outer surface. The tapered portion extends along the winding direction and is cut to form a tapered end. The tapered end of the negative electrode extends beyond the tapered end of the positive electrode along the winding direction. A positive electrode tape is adhered to the tapered portion of the positive electrode, and the positive electrode tape also covers at least the tapered end of the positive electrode. A negative electrode tape is adhered to the tapered portion of the negative electrode, and the negative electrode tape also covers at least the tapered end of the negative electrode. The heat resistance of the positive electrode tape is higher than that of the negative electrode tape.

[0007] In one embodiment of the present invention, the chemical corrosion resistance of the positive electrode tape is higher than that of the negative electrode tape.

[0008] In one embodiment of the present invention, the positive electrode tape includes a substrate and an adhesive layer coated on one or both sides of the substrate. The adhesive layer is adhered to the end portion of the positive electrode sheet. The substrate includes at least one thin film material, which is polyimide or polyvinyl fluoride.

[0009] In one embodiment of the present invention, the negative electrode tape includes a substrate and an adhesive layer coated on one or both sides of the substrate. The adhesive layer is adhered to the end portion of the negative electrode sheet. The substrate includes at least one thin film material, which is polyethylene terephthalate.

[0010] In one embodiment of this utility model, the positive electrode tape is a first color, and the negative electrode tape is a second color, wherein the first color and the second color are different colors.

[0011] In one embodiment of the present invention, the positive electrode sheet includes a positive electrode active material region, a tab adhesive region, and a positive electrode tab region arranged sequentially along the axial direction of the electrode assembly; the negative electrode sheet includes a negative electrode active material region and a negative electrode tab region arranged sequentially along the axial direction of the electrode assembly.

[0012] Along the axial direction of the electrode assembly, the positive electrode tape completely covers the positive active material region and the tab adhesive region at the tail end of the positive electrode sheet, and partially covers the positive tab region; the negative electrode tape completely covers the negative active material region at the tail end of the negative electrode sheet, and partially covers the negative tab region.

[0013] Along the axial direction of the electrode assembly, the width of the positive electrode tape covering the positive electrode tab area is greater than the width of the negative electrode tape covering the negative electrode tab area.

[0014] In one embodiment of this utility model,

[0015] Along the axial direction of the electrode assembly, the positive electrode tape has a first positive terminal adhered to the positive electrode tab region and a second positive terminal away from the positive electrode tab region. The width of the first positive terminal extending beyond the positive electrode tab region along the axial direction toward the positive electrode tab region is greater than the width of the second positive terminal extending beyond the positive electrode active material region along the axial direction away from the positive electrode tab region.

[0016] Along the axial direction of the electrode assembly, the negative electrode tape has a first negative terminal adhered to the negative electrode tab region and a second negative terminal away from the negative electrode tab region. The width of the second negative terminal extending beyond the negative electrode active material region along the axial direction away from the negative electrode tab region is greater than the width of the second positive terminal extending beyond the positive electrode active material region along the axial direction away from the positive electrode tab region.

[0017] In one embodiment of the present invention, the length of the positive electrode tape along the winding direction is less than the length of the negative electrode tape along the winding direction; the positive electrode tape partially covers the tail portion of the positive electrode sheet and partially extends beyond the tail end of the positive electrode sheet along the winding direction, the negative electrode tape partially covers the tail portion of the negative electrode sheet and partially extends beyond the tail end of the negative electrode sheet along the winding direction, the length of the positive electrode tape extending beyond the tail end of the positive electrode sheet is less than the length covering the tail portion of the positive electrode sheet, and the length of the negative electrode tape extending beyond the tail end of the negative electrode sheet is greater than the length covering the tail portion of the negative electrode sheet;

[0018] The positive electrode tape includes a thick positive electrode region and a thin positive electrode region, wherein the thickness of the thick positive electrode region is greater than the thickness of the thin positive electrode region, and the thin positive electrode region is located near the free end of the positive electrode tape.

[0019] The negative electrode tape includes a thick negative electrode region and a thin negative electrode region. The thickness of the thick negative electrode region is greater than the thickness of the thin negative electrode region. The thin negative electrode region is located near the free end of the negative electrode tape.

[0020] Based on the same concept, this utility model also provides a battery pack, including the single battery cell as described above.

[0021] Based on the same concept, this utility model also provides an electrical device, including the single battery as described above.

[0022] The beneficial effects of this utility model are as follows: This utility model proposes a single battery, battery pack, and electrical device. By having the tail end of the negative electrode sheet extend beyond the tail end of the positive electrode sheet along the winding direction, and having a positive electrode tape adhered to the tail end of the positive electrode sheet, the positive electrode tape at least covers the tail end of the positive electrode sheet. Similarly, a negative electrode tape is adhered to the tail end of the negative electrode sheet, and the negative electrode tape at least covers the tail end of the negative electrode sheet. The heat resistance of the positive electrode tape is higher than that of the negative electrode tape. Thus, through differentiated treatment of the positive and negative electrode tapes, the specific needs of the positive and negative electrode sheets are met, ensuring that the characteristics of the positive and negative electrode tapes meet the usage requirements, preventing thermal and mechanical failures, and ensuring the stability and safety of the battery cell. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0024] In the attached diagram:

[0025] Figure 1 A cross-sectional view of a winding core provided in an embodiment of this utility model;

[0026] Figure 2 This is a cross-sectional view of the connection between the positive electrode tape and the positive electrode sheet provided in one embodiment of the present invention;

[0027] Figure 3 This is a cross-sectional view of the connection between the negative electrode tape and the negative electrode sheet provided in one embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram along the axial direction of the tail portion of the positive electrode sheet provided in one embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram along the axial direction of the tail portion of the negative electrode sheet provided in one embodiment of the present invention.

[0030] The attached figures are labeled as follows:

[0031] 1-Positive electrode plate; 11-Tail end of the positive electrode plate; 11a-Tail end of the positive electrode plate; 110-Positive current collector;

[0032] 120 - Positive electrode active layer; 101 - Positive electrode active material region; 102 - Tab gel region; 103 - Positive electrode tab region;

[0033] 103a - Welding area of ​​the positive electrode tab;

[0034] 2-Negative electrode; 21-Tail end of negative electrode; 21a-Tail end of negative electrode; 210-Negative current collector;

[0035] 220 - Negative electrode active layer; 201 - Negative electrode active material region; 202 - Negative electrode tab region; 202a - Welding region of negative electrode tab;

[0036] 3-Septum;

[0037] 4-Positive electrode tape; 401-First positive electrode; 402-Second positive electrode; 41-Thick positive electrode region; 42-Thin positive electrode region;

[0038] 5 - Negative electrode tape; 501 - First negative electrode; 502 - Second negative electrode; 51 - Thick negative electrode region; 52 - Thin negative electrode region. Detailed Implementation

[0039] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0040] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0041] In the following description, numerous details are explored to provide a more thorough explanation of embodiments of the present invention. However, it will be apparent to those skilled in the art that embodiments of the present invention may be practiced without these specific details. In other embodiments, well-known structures and devices are shown in block diagram form rather than in detail to avoid obscuring embodiments of the present invention.

[0042] Please see Figure 1 , Figure 1 The single battery provided in one embodiment of the present utility model includes: an electrode assembly, including a positive electrode 1, a separator 3 and a negative electrode 2 arranged by winding or stacking, wherein the separator 3 is located between adjacent positive electrode 1 and negative electrode 2, and the positive electrode 1, negative electrode 2 and separator 3 are alternately wound to form a core or alternately stacked to form a stack.

[0043] The electrode assembly has an outer surface formed by a diaphragm 3. Both the positive electrode 1 and the negative electrode 2 have a tail portion near the outer surface. The tail portion extends along the winding direction and is cut to form a tail end. The tail end 21a of the negative electrode extends beyond the tail end 11a of the positive electrode along the winding direction. The tail end 11 of the positive electrode is attached with a positive electrode tape 4, which also covers at least the tail end 11a of the positive electrode. The tail end 21 of the negative electrode is attached with a negative electrode tape 5, which also covers at least the tail end 21a of the negative electrode. The heat resistance of the positive electrode tape 4 is higher than that of the negative electrode tape 5.

[0044] In this example, the electrode assembly has an outer surface formed by the separator 3; the positive electrode 1, the negative electrode 2, and the separator 3 all have a starting portion near the center of the electrode assembly and a ending portion near the outer surface of the electrode assembly. Specifically, the ending portion 11 of the positive electrode 1 refers to the coiled end of the positive electrode 1 along the winding or stacking direction, and the ending portion 21 of the negative electrode 2 refers to the coiled end of the negative electrode 2 along the winding or stacking direction.

[0045] The positive electrode 1 includes at least a positive current collector 110 and a positive active layer 120 coated on one or both sides of the positive current collector 110. The positive current collector 110 is typically made of aluminum foil, and the positive active layer 120 is typically made of lithium oxides such as NCM (lithium nickel manganese cobalt oxide), LCO (lithium cobalt oxide), LFP (lithium iron phosphate), LMO (lithium manganese oxide), and LMFP (lithium manganese iron phosphate). The negative electrode 2 includes at least a negative current collector 210 and a negative active layer 220 coated on one or both sides of the negative current collector 210. The negative current collector 210 is typically made of copper foil, and the negative active layer 220 is typically made of carbon-based compounds (such as natural graphite, artificial graphite, hard carbon, and soft carbon), silicon-based compounds (such as silicon and silicon-carbon composites), titanium-based compounds (such as lithium titanate), and alloy materials (such as Li-Sn alloys and Li-Al alloys). The separator 3 is typically made of polyolefins, such as polypropylene (PP) and polyethylene (PE).

[0046] See Figure 4 and Figure 5 The positive electrode 1 includes a positive electrode active material region 101, a tab adhesive region 102, and a positive electrode tab region 103 arranged sequentially along the axial direction of the core; the negative electrode 2 includes a negative electrode active material region 201 and a negative electrode tab region 202 arranged sequentially along the axial direction of the core. The positive electrode active material region 101 is the region coated with a positive electrode active layer 120, and the negative electrode active material region 201 is the region coated with a negative electrode active layer 220.

[0047] The positive electrode tape 4 and negative electrode tape 5 possess the following characteristics: High adhesion: Both tapes must have high adhesion to prevent material loss and burrs, ensuring the stability and safety of the core. High temperature resistance: Tapes 4 and 5 must maintain their performance at high temperatures to prevent adhesive failure due to temperature increases. Electrolyte corrosion resistance: The materials of tapes 4 and 5 must be resistant to electrolyte corrosion to prevent erosion and ensure long-term stability. Oxidation-reduction resistance: Tapes 4 and 5 must resist oxidation-reduction reactions to protect the core's performance. Strong mechanical properties: Tapes 4 and 5 must possess good mechanical strength to withstand certain tensile and tearing forces, ensuring stability during use.

[0048] However, based on the above performance, it is also necessary to consider the differentiated treatment of positive electrode tape 4 and negative electrode tape 5 to meet their specific needs.

[0049] The positive electrode tape 4 has a higher heat resistance than the negative electrode tape 5. This prevents micro-cracks from forming at the cut edges due to localized overheating during hot pressing. The hot pressing process for the positive and negative electrode tapes 4 and 5 is achieved using hot pressing equipment. The hot pressing temperature typically needs to be adjusted based on the heat resistance of the materials of the positive and negative electrode tapes 4 and 5, as well as the heat resistance of the separator. Excessive temperature may lead to over-melting of the tapes or pore-closing of the separator, while insufficient temperature will result in weak adhesion. By setting the heat resistance of the positive electrode tape 4 to be higher than that of the negative electrode tape 5, the requirements for secondary plastic deformation of the positive and negative electrode tapes 4 and 5 can be met, ensuring that the positive electrode tape 4, negative electrode tape 5, positive electrode sheet 1, negative electrode sheet 2, and separator 3 achieve a micron-level flatness, preventing electric field concentration, lithium plating, and separator puncture at the edges.

[0050] More specifically, the heat resistance of the positive electrode tape 4 and the negative electrode tape 5 can be characterized by long-term operating temperature (Tlong), short-term tolerance temperature (Tshort), and dimensional change rate (ΔL / L). Long-term operating temperature (Tlong) refers to the tape's ability to operate stably at 260°C for an extended period without significant physical or chemical changes. Short-term tolerance temperature (Tshort) refers to the tape's ability to withstand a short-term (e.g., 1 hour) temperature of 310°C without significant physical or chemical changes. Dimensional change rate (ΔL / L) refers to the tape's dimensional change rate not exceeding 2% at 260°C. When testing the heat resistance of the positive electrode tape 4 and the negative electrode tape 5, both can be tested under uniform simulated battery internal environmental conditions. It is understood that during the long-term operating temperature (Tlong) test, an industry-default acceleration factor can be used to simulate long-term operating conditions to complete the Tlong performance test. In this application, the above three indicators can be selected individually or in combination to evaluate the difference in heat resistance performance between the positive electrode tape 4 and the negative electrode tape 5. It is understood that when specifically selecting heat resistance performance tests, the key test conditions for the above three indicators, such as the temperature, test time, and percentage change rate standards mentioned above, can be adaptively adjusted according to industry common practice to match specific test methods and test environments. This application does not impose any limitations on this. For example, in the long-term use temperature (Tlong) test, a temperature of 260°C can be used to characterize long-term heat resistance, and a uniform 10-hour (h) accelerated aging test can be selected. Of course, for more stringent requirements or higher extrapolation confidence, the test time can be extended to 24 hours.

[0051] The positive electrode tape 4, which has high heat resistance, utilizes its high glass transition temperature, low coefficient of thermal expansion, and oxidation resistance to transform the "cut edge" from a weak strip that is easy to peel off and oxidize into a controlled, stable, and insulating barrier, preventing thermal and mechanical failure.

[0052] Among them, the positive electrode active layer 120 (made of NCM (lithium nickel cobalt manganese oxide), LCO (lithium cobalt oxide), LFP (lithium iron phosphate), etc.) will face the triple high conditions of high temperature, high stress and high potential in the "cutting edge" area. It is necessary to rely on the positive electrode tape 4 with high heat resistance to reduce the risk. The specific reasons are: 1. The phase transition temperature of oxides such as high nickel NCM (lithium nickel cobalt manganese oxide) is low. The phase transition temperature of NCM (lithium nickel cobalt manganese oxide) is about 150℃. Laser cutting or hot pressing cutting will cause the edge temperature to reach more than 200℃ instantly. The phase transition will be accompanied by oxygen release. If the adhesive layer of the positive electrode tape 4 is not resistant to high temperature, it will carbonize and lose its adhesive force, resulting in the detachment of active material particles. 2. The adhesive has a low thermal softening point. PVDF (polyvinylidene fluoride) has a melting point of 160℃~170℃, and its bonding strength drops sharply after softening. If the substrate of the positive electrode tape 4 softens below 120℃, it cannot bind the end of the positive electrode sheet 1, and the coating will peel off under winding tension. 3. The aluminum foil used in the positive electrode current collector 110 of the positive electrode sheet 1 has a high coefficient of thermal expansion, which is higher than that of the positive electrode active layer 120. Shear stress is generated at the edge during thermal cycling. The high-temperature resistant positive electrode tape 4 can act as a "thermal pad" to absorb the difference in expansion and prevent delamination cracks. 4. High potential aggravates oxidation. The positive electrode potential is relatively high. Ordinary tapes will be oxidized and decomposed above 80℃. The heat-resistant positive electrode tape 4 remains chemically inert at 150℃, blocking the side reactions between the edge and the electrolyte.

[0053] Furthermore, in some embodiments, the oxidation resistance of the positive electrode tape 4 is higher than that of the negative electrode tape 5. The end portion 11 of the positive electrode sheet is in a strong oxidizing environment, and the positive electrode sheet 1, due to its high potential, is easily affected by oxidation. If the positive electrode tape 4 lacks oxidation resistance, its adhesiveness may fail, leading to a decrease in core performance. The positive electrode tape 4 may undergo a redox reaction with the active ingredients, thereby affecting the core's capacity and internal stability.

[0054] In some embodiments, the positive electrode tape 4 exhibits higher chemical corrosion resistance than the negative electrode tape 5. Specifically, the corrosion resistance of the positive electrode tape 4 and the negative electrode tape 5 is characterized by their excellent resistance to various chemical media. The chemical system can be simulated using a complete electrolyte environment containing lithium salts, and stability tests within the electrochemical window are performed through corrosion resistance tests and electrochemical tests simulating the internal potential environment of the battery. The electrochemical tests simulate the internal potential environment of the battery, but more importantly, they simulate the high-potential environment of the positive electrode 1.

[0055] In some embodiments, the positive electrode tape 4 includes a substrate and an adhesive layer coated on one or both sides of the substrate. The adhesive layer is adhered to the end portion 11 of the positive electrode sheet. The substrate of the positive electrode tape 4 includes at least one thin film material, which is polyimide (PI) or polyvinyl fluoride (PTFE). Specifically, PI material has excellent high-temperature resistance (long-term temperature resistance >250℃) and high chemical stability. PTFE material has high and low temperature resistance; PTFE can be used in a wide temperature range from -200℃ to 260℃, and has good chemical corrosion resistance and electrical insulation properties.

[0056] In some embodiments, the negative electrode tape 5 includes a substrate and an adhesive layer coated on one or both sides of the substrate. The adhesive layer is adhered to the end portion 21 of the negative electrode sheet. The substrate of the negative electrode tape 5 includes at least one thin film material, which is polyethylene terephthalate (PET). Specifically, PET material has good dimensional stability, thermal stability, chemical stability, insulation, adhesion, initial tack, and adhesion. Since there is no similar oxidation resistance requirement on the negative electrode side, a lower-cost conventional insulating tape can be selected.

[0057] In some embodiments, the positive electrode tape 4 is a first color, and the negative electrode tape 5 is a second color, wherein the first color and the second color are different colors. Specifically, multiple colors can be achieved on polyimide (PI) tapes by methods such as coating a color layer, adding pigments or dyes, utilizing nanoparticles, using photonic crystals, and modifying the chemical structure of polyimide. These methods can be selected according to specific application requirements and performance requirements.

[0058] By using different colored positive electrode tapes 4 and negative electrode tapes 5, identification and marking are facilitated, allowing for quick differentiation between the two and reducing the risk of incorrect connections. For example, yellow can be used to mark positive electrode tape 4 and blue to mark negative electrode tape 5, making it easy for operators to identify them quickly. Other colors can also be used in other examples; there are no specific limitations. Furthermore, color differentiation effectively prevents incorrect connections when connecting batteries or circuits, reducing the risk of short circuits or other safety hazards. Different colored positive electrode tapes 4 and negative electrode tapes 5 also remind operators of the electrode polarity, enhancing safety awareness.

[0059] See Figure 4 and Figure 5In some embodiments, the positive electrode sheet 1 includes a positive active material region 101, a tab adhesive region 102, and a positive tab region 103 arranged sequentially along the axial direction of the core; the negative electrode sheet 2 includes a negative active material region 201 and a negative tab region 202 arranged sequentially along the axial direction of the core; along the axial direction of the core, the positive electrode tape 4 completely covers the positive active material region 101 and the tab adhesive region 102 of the tail portion 11 of the positive electrode sheet, and also covers part of the positive tab region 103; the negative electrode tape 5 completely covers the negative active material region 201 of the tail portion 21 of the negative electrode sheet, and also covers part of the negative tab region 202.

[0060] Specifically, along the axial direction of the core, the positive electrode tape 4 completely covers the positive electrode active material region 101 and the tab adhesive region 102 of the tail portion 11 of the positive electrode sheet, and also partially covers the positive electrode tab region 103. If the positive electrode tape 4 only covers part of the active material region, the uncovered areas of the positive electrode tape 4 are prone to material loss.

[0061] If the positive electrode tape 4 does not cover the tab adhesive area 102 (AT9 area) of the end portion 11 of the positive electrode sheet, the tab adhesive area 102 is easily soaked and detached by the electrolyte, resulting in the exposure of the positive electrode tab area 103, increasing the risk of short circuit due to contact with the casing. The positive electrode tape 4 covers the tab adhesive area 102 (AT9 area) along the axial direction of the core. On the one hand, this prevents the tab adhesive area 102 from being corroded by the electrolyte. Since the end portion 11 of the positive electrode sheet is close to the inner wall of the battery casing, the tab adhesive area 102 (AT9 area) is prone to detachment. The positive electrode tape 4 completely covers the tab adhesive area 102 (AT9 area) along the axial direction of the core, isolating the exposed tab adhesive area 102 from electrolyte contact and corrosion. On the other hand, it reduces the risk of foil wrinkling in the tab adhesive area 102 (AT9 area) during winding. The positive electrode tape 4 covering the tab adhesive area 102 along the axial direction of the core can improve battery yield by 5% to 8%.

[0062] The welding area 103a of the positive electrode tab must be completely exposed. Otherwise, if the positive electrode tape 4 covers the entire positive electrode tab area 103, the energy transfer of the welding head will be hindered due to the isolation caused by the positive electrode tape 4 during welding, resulting in a poor weld. Covering part of the positive electrode tab area 103 with the positive electrode tape 4 can also avoid insufficient protection at the root of the positive electrode tab area 103.

[0063] Along the axial direction of the core, the negative electrode tape 5 completely covers the negative electrode active material region 201 of the tail portion 21 of the negative electrode sheet, and also partially covers the negative electrode tab region 202. Because the negative electrode tab region 202 is thinner, the welding area 202a of the negative electrode tab has a higher risk of contamination. Furthermore, the fact that the negative electrode tape 5 partially covers the negative electrode tab region 202 also prevents insufficient protection at the root of the negative electrode tab region 202.

[0064] In the above embodiment, along the axial direction of the core, the width W1 of the positive electrode tape 4 covering the positive electrode tab area 103 is greater than the width W3 of the negative electrode tape 5 covering the negative electrode tab area 202. Specifically, in this example, the positive electrode tab area 103 is made of aluminum foil, and the negative electrode tab area 202 is made of copper foil. Copper foil has better ductility than aluminum foil and requires a larger allowance for movement. W1>W3, and W1-W3≈0.3~0.5mm. The corrosion resistance requirement of aluminum foil is greater than that of copper foil, and the stress in the positive electrode tab area 103 is more concentrated.

[0065] In the above embodiment, along the axial direction of the core, the positive electrode tape 4 has a first positive terminal 401 adhered to the positive electrode tab region 103 and a second positive terminal 402 away from the positive electrode tab region 103. The width W1 of the first positive terminal 401 extending beyond the positive electrode tab region 103 in the axial direction toward the positive electrode tab region 103 (i.e., the width of the positive electrode tape 4 covering the positive electrode tab region 103) is greater than the width W2 of the second positive terminal 402 extending beyond the positive electrode active material region 101 in the axial direction away from the positive electrode tab region 103.

[0066] Specifically, the first positive terminal 401 of the positive electrode tape 4 extends beyond the positive electrode active material region 101 in a direction close to the positive electrode tab region 103, and the second positive terminal 402 of the positive electrode tape 4 extends beyond the positive electrode active material region 101 in a direction away from the positive electrode tab region 103. W1>W2, and W1 / W2≈1.5~2.0. The tab region 102 (AT9 region) requires stronger corrosion protection, while the edge of the positive electrode active material region 101 only needs crack prevention.

[0067] Along the axial direction of the core, the negative electrode tape 5 has a first negative end 501 adhered to the negative electrode tab region 202 and a second negative end 502 away from the negative electrode tab region 202. The width W4 of the second negative end 502 extending beyond the negative electrode active material region 201 in the axial direction away from the negative electrode tab region 202 is greater than the width W2 of the second positive end 402 extending beyond the positive electrode active material region 101 in the axial direction away from the positive electrode tab region 103.

[0068] Specifically, the first negative end 501 of the negative electrode tape 5 extends beyond the negative electrode active material region 201 in the direction close to the negative electrode tab region 202, and the second negative end 502 of the negative electrode tape 5 extends beyond the negative electrode active material region 201 in the direction away from the negative electrode tab region 202. W4 > W2, W4 - W2 ≈ 0.3~0.8mm. Negative electrode expansion > positive electrode expansion (13% > 3%), W4 requires a larger buffer space; the width of the negative electrode sheet 2 is greater than the width of the positive electrode sheet 1, so W4 needs to be increased to prevent the bottom from contacting the shell.

[0069] In the above embodiment, the length M1 of the positive electrode tape 4 along the winding direction is less than the length M2 of the negative electrode tape 5 along the winding direction. Specifically, the separator 3 covers the negative electrode sheet 2 around its circumference and is cut a certain distance beyond the cut point of the negative electrode sheet 2 to complete the complete coverage of the negative electrode sheet 2. Therefore, at the cut point of the negative electrode sheet 2, it needs to withstand greater winding internal stress, thus requiring a longer length relative to the positive electrode tape 4 of the positive electrode sheet 1. In this example, M1 is 7 mm and M2 is 11 mm.

[0070] In the above embodiment, the positive electrode tape 4 partially covers the tail portion 11 of the positive electrode sheet along the winding direction and partially extends beyond the tail end 11a of the positive electrode sheet. The negative electrode tape 5 partially covers the tail portion 21 of the negative electrode sheet along the winding direction and partially extends beyond the tail end 21a of the negative electrode sheet. The length N2 of the positive electrode tape 4 extending beyond the tail end 11a of the positive electrode sheet is less than the length N1 covering the tail portion 11 of the positive electrode sheet, and the length N4 of the negative electrode tape 5 extending beyond the tail end 21a of the negative electrode sheet is greater than the length N3 covering the tail portion 21 of the negative electrode sheet. The lengths N1 and N2 are close, the lengths N3 and N4 are close, and the difference between N1 and N2 is no greater than 2 mm, and the difference between N3 and N4 is no greater than 2 mm. This design better disperses the radial stress brought by the tape at the tail portion, resulting in a more uniform stress distribution. In this example, N1 is 4 mm, N2 is 3 mm, N3 is 5 mm, and N4 is 6 mm.

[0071] Furthermore, along the winding direction, the length N1 of the positive electrode tape 4 covering the end portion 11 of the positive electrode sheet is less than the length N3 of the negative electrode tape 5 covering the end portion 21 of the negative electrode sheet. In this example, N1 is 4 mm and N3 is 5 mm. Since the end portion 11 of the positive electrode sheet is closer to the front side of the winding direction, and the end portion 21 of the negative electrode sheet is closer to the rear side of the winding direction and directly contacts the subsequently cut separator, the negative electrode sheet also needs to bear the constraint force of the separator. This arrangement can disperse the radial stress of the tape at the end portion and avoid stress concentration.

[0072] See Figure 2 and Figure 3 In some embodiments, the positive electrode tape 4 includes a thick positive electrode region 41 and a thin positive electrode region 42, with the thickness of the thick positive electrode region 41 being greater than the thickness of the thin positive electrode region 42, and the thin positive electrode region 42 being located near the free end of the positive electrode tape 4; the negative electrode tape 5 includes a thick negative electrode region 51 and a thin negative electrode region 52, with the thickness of the thick negative electrode region 51 being greater than the thickness of the thin negative electrode region 52, and the thin negative electrode region 52 being located near the free end of the negative electrode tape 5. This ensures sufficient adhesive strength while avoiding stress concentration. By combining thick and thin regions, sufficient adhesive strength is provided while the thin region reduces interference.

[0073] This utility model also provides a battery pack, including the single battery cells described in the above embodiments.

[0074] This utility model also provides an electrical device, including a single battery as described in the above embodiments.

[0075] In summary, the present invention provides a single-cell battery, a battery pack, and an electrical device. By attaching a positive electrode tape 4 to the end 11 of the positive electrode sheet and a negative electrode tape 5 to the end 21 of the negative electrode sheet, and by having the positive electrode tape 4 have higher heat resistance than the negative electrode tape 5, the differentiated treatment of the positive electrode tape 4 and the negative electrode tape 5 can meet their specific needs, ensure that the characteristics of the positive electrode tape 4 and the negative electrode tape 5 meet the usage requirements, prevent thermal failure and mechanical failure, and ensure the stability and safety of the battery cell.

[0076] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A single-cell battery, characterized in that, The device includes an electrode assembly comprising a positive electrode, a separator, and a negative electrode arranged in a wound or stacked manner, wherein the separator is located between adjacent positive and negative electrode sheets. The electrode assembly has an outer surface formed by the diaphragm. Both the positive electrode and the negative electrode have a tapered portion near the outer surface. The tapered portion extends along the winding direction and is cut to form a tapered end. The tapered end of the negative electrode extends beyond the tapered end of the positive electrode along the winding direction. A positive electrode tape is adhered to the tapered portion of the positive electrode, and the positive electrode tape also covers at least the tapered end of the positive electrode. A negative electrode tape is adhered to the tapered portion of the negative electrode, and the negative electrode tape also covers at least the tapered end of the negative electrode. The heat resistance of the positive electrode tape is higher than that of the negative electrode tape.

2. The single-cell battery according to claim 1, characterized in that, The positive electrode tape has higher chemical corrosion resistance than the negative electrode tape.

3. The single-cell battery according to claim 2, characterized in that, The positive electrode tape includes a substrate and an adhesive layer coated on one or both sides of the substrate. The adhesive layer is adhered to the end portion of the positive electrode sheet. The substrate includes at least one thin film material, which is polyimide or polyvinyl fluoride.

4. The single-cell battery according to claim 2, characterized in that, The negative electrode tape includes a substrate and an adhesive layer coated on one or both sides of the substrate. The adhesive layer is adhered to the end portion of the negative electrode sheet. The substrate includes at least one thin film material, which is polyethylene terephthalate.

5. The single-cell battery according to claim 1, characterized in that, The positive electrode tape is a first color, and the negative electrode tape is a second color, wherein the first color and the second color are different colors.

6. The single-cell battery according to claim 1, characterized in that, The positive electrode sheet includes a positive electrode active material region, a tab adhesive region, and a positive electrode tab region arranged sequentially along the axial direction of the electrode assembly; the negative electrode sheet includes a negative electrode active material region and a negative electrode tab region arranged sequentially along the axial direction of the electrode assembly. Along the axial direction of the electrode assembly, the positive electrode tape completely covers the positive active material region and the tab adhesive region at the tail end of the positive electrode sheet, and also covers part of the positive electrode tab region; the negative electrode tape completely covers the negative active material region at the tail end of the negative electrode sheet, and also covers part of the negative electrode tab region. Along the axial direction of the electrode assembly, the width of the positive electrode tape covering the positive electrode tab area is greater than the width of the negative electrode tape covering the negative electrode tab area.

7. The single-cell battery according to claim 6, characterized in that, Along the axial direction of the electrode assembly, the positive electrode tape has a first positive terminal adhered to the positive electrode tab region and a second positive terminal away from the positive electrode tab region. The width of the first positive terminal extending beyond the positive electrode tab region along the axial direction toward the positive electrode tab region is greater than the width of the second positive terminal extending beyond the positive electrode active material region along the axial direction away from the positive electrode tab region. Along the axial direction of the electrode assembly, the negative electrode tape has a first negative terminal adhered to the negative electrode tab region and a second negative terminal away from the negative electrode tab region. The width of the second negative terminal extending beyond the negative electrode active material region along the axial direction away from the negative electrode tab region is greater than the width of the second positive terminal extending beyond the positive electrode active material region along the axial direction away from the positive electrode tab region.

8. The single-cell battery according to claim 1, characterized in that, The length of the positive electrode tape along the winding direction is less than the length of the negative electrode tape along the winding direction; the positive electrode tape partially covers the tail portion of the positive electrode sheet and partially extends beyond the tail end of the positive electrode sheet along the winding direction, the negative electrode tape partially covers the tail portion of the negative electrode sheet and partially extends beyond the tail end of the negative electrode sheet along the winding direction, the length of the positive electrode tape extending beyond the tail end of the positive electrode sheet is less than the length covering the tail portion of the positive electrode sheet, and the length of the negative electrode tape extending beyond the tail end of the negative electrode sheet is greater than the length covering the tail portion of the negative electrode sheet; The positive electrode tape includes a thick positive electrode region and a thin positive electrode region, wherein the thickness of the thick positive electrode region is greater than the thickness of the thin positive electrode region, and the thin positive electrode region is located near the free end of the positive electrode tape. The negative electrode tape includes a thick negative electrode region and a thin negative electrode region. The thickness of the thick negative electrode region is greater than the thickness of the thin negative electrode region. The thin negative electrode region is located near the free end of the negative electrode tape.

9. A battery pack, characterized in that, Includes the single-cell battery as described in any one of claims 1-8.

10. An electrical appliance, characterized in that, Includes the single-cell battery as described in any one of claims 1-8.

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