Battery cell and battery

Abstract

The utility model provides a battery cell and battery, including: positive pole piece, diaphragm and negative pole piece, positive pole piece, diaphragm and negative pole piece are laminated in proper order and wind to form the coiled battery cell, the coiled battery cell includes bending area and straight area, the positive pole piece, diaphragm and negative pole piece have bending radian in the bending area, the straight area has bending radian in the straight area, the straight area has bending radian in the straight area, and the straight area has bending radian in the straight area. The positive plate, the diaphragm and the negative plate are straightly arranged in the straight area, the positive plate comprises a bent section and a straight section, the bent section is located in the bent area, and the straight section is located in the straight area; the gummed paper is arranged between the positive plate and the negative plate, the gummed paper corresponds to the bent section, a through hole penetrating through the gummed paper is formed in the gummed paper, the through hole is used for allowing lithium ions to pass through, and the gummed paper is made of a deformable material. According to the battery cell disclosed by the utility model, the lithium precipitation phenomenon at the bending position of the battery cell can be effectively avoided.

Description

Technical Field

[0001] This utility model relates to the field of new energy technology, and in particular to a battery cell and battery. Background Technology

[0002] With continuous technological advancements and innovation, the demand for various smart devices, especially smartphones and computers, is growing daily. The widespread adoption of these devices has led to higher requirements for the performance and safety of smart products. Among numerous performance indicators, energy density and safety have become the primary focus for both consumers and manufacturers. To meet these demands, higher coating weights and compaction are employed, posing increasing challenges to the charging capacity of the system and making batteries more prone to lithium plating. During the winding process of high-density batteries, gaps may appear between the electrodes at the bending points. When these gaps occur, there is a lack of electrolyte and electrolyte bridging, resulting in severe lithium plating on the positive electrode. Therefore, a battery cell that can effectively prevent lithium plating at the bending points of the positive electrode is needed. Utility Model Content

[0003] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a battery cell that can effectively avoid lithium plating at the bending points of the battery cell.

[0004] This utility model also proposes a battery.

[0005] A battery cell according to a first aspect of the present invention includes: a positive electrode, a separator, and a negative electrode, wherein the positive electrode, the separator, and the negative electrode are sequentially stacked and wound to form the battery cell. The battery cell includes a bent region and a straight region. The positive electrode, the separator, and the negative electrode have a bending arc in the bent region, and the positive electrode, the separator, and the negative electrode are straight in the straight region. The positive electrode includes a bent section and a straight section, wherein the bent section is located in the bent region, and the straight section is located in the straight region. Adhesive paper is disposed between the positive electrode and the negative electrode, and the adhesive paper corresponds to the bent section. A through hole is formed in the adhesive paper to allow lithium ions to pass through. The adhesive paper is a deformable material.

[0006] The battery cell according to the first aspect of the present invention has at least the following beneficial effects: by providing deformable adhesive paper in the bending area of ​​the battery cell, the gaps that are prone to occur in the bending area are filled, thereby avoiding gaps in the bending area. The adhesive paper also absorbs more electrolyte, preventing the bending area from lacking electrolyte, and at the same time preventing the electrolyte in the bending area from breaking bridges, thereby effectively preventing lithium plating in the bending area.

[0007] According to some embodiments of the present invention, the thickness of the adhesive paper in the first direction is not less than 10 μm and not more than 20 μm, where the first direction is the thickness direction of the positive electrode sheet.

[0008] According to some embodiments of the present invention, the aperture of the through hole is not less than 0.1 μm and not greater than 0.3 μm.

[0009] According to some embodiments of the present invention, the adhesive tape is disposed between the positive electrode sheet and the separator and is applied to the curved section.

[0010] According to some embodiments of the present invention, the width direction of the positive electrode sheet is the second direction, and the width of the adhesive paper in the second direction is not greater than the width of the positive electrode sheet.

[0011] According to some embodiments of the present invention, the positive electrode sheet has a first edge and a second edge along a second direction, and the adhesive tape is disposed between the first edge and the second edge, with the distance between the adhesive tape and both the first edge and the second edge not exceeding 50 μm.

[0012] According to some embodiments of the present invention, the length of the adhesive paper on the positive electrode sheet of the first layer of the battery cell in the third direction is L, the third direction is the extension direction of the positive electrode sheet, the thickness of the positive electrode sheet is A, the thickness of the negative electrode sheet is B, the thickness of the separator is C, and the length of the adhesive paper on the positive electrode sheet of the Nth layer of the battery cell in the third direction is S, where S=L+π*[(N-1)*(A+B+2C)] / 2.

[0013] According to some embodiments of the present invention, the positive electrode sheet has two curved sections in the same layer of winding, and the adhesive paper is provided on both curved sections, and the length of the adhesive paper on the curved sections wound in the same layer is equal.

[0014] According to some embodiments of this utility model, the adhesive tape is a material that can be elastically deformed.

[0015] The battery according to a second aspect of the present invention includes the battery cell described in any one of the above embodiments.

[0016] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of a battery cell according to the present invention;

[0018] Figure 2 for Figure 1A magnified view of a portion of the image;

[0019] Figure 3 This is a schematic diagram of the adhesive paper for a battery cell according to the present invention.

[0020] Icon labels:

[0021] 1. Positive electrode; 11. Bending section; 12. Straight section; 2. Negative electrode; 3. Separator; 4. Adhesive paper; 41. Through hole; 5. Bending area; 6. Straight area. Detailed Implementation

[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0023] In the description of this utility model, it should be understood that the orientation descriptions, such as up and down, are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0024] In the description of this utility model, "multiple" refers to two or more. The use of "first" and "second" is for distinguishing technical features only and should not be construed as indicating or implying relative importance, or implicitly indicating the number of technical features or their sequential relationship.

[0025] In the description of this utility model, unless otherwise explicitly defined, terms such as "setting," "installation," and "connection" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this utility model in conjunction with the specific content of the technical solution.

[0026] Reference Figure 1 , Figure 2 and Figure 3The battery cell in the first embodiment of this utility model includes: a positive electrode 1, a separator 3, adhesive tape 4, and a negative electrode 2. The positive electrode 1, separator 3, and negative electrode 2 are stacked and wound in sequence to form the battery cell. The battery cell includes a bending region 5 and a straight region 6. The positive electrode 1, separator 3, and negative electrode 2 have a bending arc in the bending region 5. The positive electrode 1, separator 3, and negative electrode 2 are straight in the straight region 6. The positive electrode 1 includes a bent section 11 and a straight section 12. The bent section 11 is located in the bending region 5, and the straight section 12 is located in the straight region 6. In this design, a portion of the positive electrode 1 is located in the bending region 5, and another portion is located in the straight region 6. The positive electrode 1 located in the bending region 5 has a certain bending arc, i.e., a bending segment, while the positive electrode 1 located in the straight region 6 is set straight, i.e., a straight segment 12. The bending segment and the straight segment 12 on the positive electrode 1 are alternately arranged along the extension direction of the positive electrode 1. In the prior art, after the winding of the battery cell is completed, a straight section is formed in the middle of the winding battery cell, and the positive electrode 1 in the straight section, i.e., the straight region 6, is the straight segment 12. Two bending sections, i.e., bending regions 5, are formed at both ends of the straight segment 12, and the positive electrode 1 is a bending segment in the bending section. The positive electrode 1 in the bending section is bent into a semi-circle, and the two straight segments 12 of the two positive electrode 1 are connected at both ends of the semi-circle. In the bending region 5, the positive electrode 1, separator 3 and negative electrode 2 will deform, resulting in greater pressure between them. After the cell is used multiple times, the positive electrode 1 and negative electrode 2 will expand and contract, making it easier for gaps to form between them, leading to ion bridging, causing black spots and lithium plating, and deteriorating the battery's cycle performance.

[0027] Adhesive tape 4 is disposed between the positive electrode 1 and the negative electrode 2, and corresponds to the bending section 11. The adhesive tape 4 has a through hole 41 that allows lithium ions to pass through. The adhesive tape 4 is made of a deformable material. When the positive electrode 1 and the negative electrode 2 are bent in the bending area 5, gaps will appear between them. The adhesive tape 4, being disposed between the positive electrode 1 and the negative electrode 2, fills these gaps, thus preventing voids from forming between them. After the adhesive tape 4 fills the gap between the positive electrode 1 and the negative electrode 2, the adhesive tape 4 absorbs the electrolyte, ensuring sufficient electrolyte between the positive electrode 1 and the negative electrode 2. This also prevents electrolyte bridging between the positive electrode 1 and the negative electrode 2 caused by the gap, effectively avoiding lithium plating in the bending area 5. The adhesive tape 4 is deformable to better adapt to the gap between the positive electrode 1 and the negative electrode 2. Specifically, the adhesive tape 4 is compressed in areas with smaller gaps between the positive electrode 1 and the negative electrode 2, resulting in a tighter fit between the positive electrode 1, the negative electrode 2, and the adhesive tape 4. Simultaneously, through holes 41 are provided on the adhesive tape 4, allowing lithium ions to pass through. This prevents lithium ion aggregation at the edges of the adhesive tape 4.

[0028] According to some embodiments of this utility model, the thickness of the adhesive tape 4 in a first direction is not less than 10 μm and not more than 20 μm, where the first direction is the thickness direction of the positive electrode 1. When the thickness of the adhesive tape 4 is too large, it will reduce the energy density of the battery cell and also affect the passage of lithium ions through the through-hole 41. Conversely, when the thickness of the adhesive tape 4 is too small, it may not be able to adequately fill the gap between the positive electrode 1 and the negative electrode 2. Therefore, the thickness of the adhesive tape 4 is limited so that it can both adequately fill the gap between the positive electrode 1 and the negative electrode 2 and allow lithium ions to pass smoothly through the through-hole 41.

[0029] According to some embodiments of this utility model, the aperture of the through-hole 41 is not less than 0.1 μm and not greater than 0.3 μm. When the aperture of the through-hole 41 is too large, it will not only reduce the structural strength of the adhesive tape 4, but may also cause air bubbles to appear in the through-hole 41. Conversely, when the aperture of the through-hole 41 is too small, it will affect the passage of lithium ions through the adhesive tape 4, causing lithium ion aggregation at the location of the adhesive tape 4 and resulting in lithium plating. Therefore, limiting the aperture of the through-hole 41 allows lithium ions to pass through quickly while preventing air bubbles from forming within the through-hole 41.

[0030] The formation of air bubbles in the active material layer of a battery is a significant problem. These tiny air pockets not only interfere with internal chemical reactions but also severely impact overall battery performance. When bubbles form in the active material layer, they occupy valuable space, reducing the effective contact area between the active material and the electrolyte. This reduction in contact area directly leads to a decrease in battery charging and discharging efficiency, thus affecting the battery's output power and range. Worse still, bubble accumulation can cause abnormal increases in internal battery pressure. As pressure increases, the battery casing may expand, and in extreme cases, even rupture. This physical damage not only shortens battery life but can also pose safety hazards. In some extreme cases, the continuous accumulation of bubbles can even trigger internal short circuits, leading to overheating and even the risk of combustion or explosion. Therefore, engineers must take a series of measures to prevent and reduce bubble formation during battery design and manufacturing. This includes optimizing battery manufacturing processes, ensuring uniform material mixing, and strictly controlling environmental conditions during battery assembly. Through these meticulous efforts, the negative impacts of bubbles can be significantly reduced, thereby ensuring battery performance and safety.

[0031] According to some embodiments of this utility model, adhesive tape 4 is disposed between the positive electrode 1 and the separator 3 and adhered to the bent section 11. When adhesive tape 4 is disposed between the positive electrode 1 and the negative electrode 2, it can be disposed between either the positive electrode 1 and the separator 3 or between the negative electrode 2 and the separator 3. When adhesive tape 4 is disposed on the positive electrode 1, the electrolyte absorbed by adhesive tape 4 can better ensure a sufficient electrolyte concentration on the positive electrode 1, thereby better preventing lithium plating on the positive electrode 1.

[0032] According to some embodiments of this utility model, the width direction of the positive electrode 1 is the second direction, and the width of the adhesive tape 4 in the second direction is not greater than the width of the positive electrode 1. The positive electrode 1 has a first edge and a second edge along the second direction, and the adhesive tape 4 is disposed between the first edge and the second edge, with the distance between the adhesive tape 4 and both the first edge and the second edge not exceeding 50 μm. This prevents the adhesive tape 4 from extending beyond the positive electrode 1 and the negative electrode 2. If the adhesive tape 4 is too far from the edge between the positive electrode 1 and the negative electrode 2, the edge position will lack electrolyte, resulting in lithium plating at the electrolyte-deficient location.

[0033] According to some embodiments of this utility model, the length of the adhesive tape 4 on the first layer of the positive electrode 1 of the battery cell in the third direction is L, where the third direction is the extension direction of the positive electrode 1. The thickness of the positive electrode 1 is A, the thickness of the negative electrode 2 is B, and the thickness of the separator 3 is C. The length of the adhesive tape 4 on the Nth layer of the positive electrode 1 of the battery cell in the third direction is S, where S = L + π * [(N-1) * (A + B + 2C)] / 2. During the winding of the battery cell, a semi-circular shape is formed in the bending area 5, and the length of the bending section 11 gradually increases from the inside to the outside of the winding layers, that is, the winding radius increases, and the winding length also increases. Therefore, the length of the adhesive tape 4 also needs to be increased to more fully fill the gap between the positive electrode 1 and the negative electrode 2 in the bending area 5.

[0034] According to some embodiments of this utility model, the positive electrode 1 has two bent sections 11 in the same layer of winding, and adhesive tape 4 is provided on both bent sections 11. The lengths of the adhesive tape 4 on the bent sections 11 wound in the same layer are equal. Providing adhesive tape 4 of equal length in the two bent sections makes the distribution of electrolyte in the adhesive tape 4 more uniform, thereby making the performance of the battery cell more stable.

[0035] According to some embodiments of this utility model, the adhesive tape 4 is made of an elastically deformable material. Because the battery cell undergoes cyclic expansion and contraction during use, the gap between the positive electrode 1 and the negative electrode 2 also cyclically increases and decreases. To prevent the adhesive tape 4 from being unable to spring back after compression, thus causing a gap between the positive electrode 1 and the negative electrode 2, the adhesive tape 4 is made of an elastically deformable material, allowing it to better fill the gap between the positive electrode 1 and the negative electrode 2.

[0036] The battery according to the second aspect of the present invention includes the battery cell of any of the above embodiments.

[0037] The energy density of a battery cell refers to the energy that can be stored per unit volume or unit mass of the cell. It is usually expressed in watt-hours per liter (Wh / L) for volumetric energy density and in watt-hours per kilogram (Wh / kg) for gravimetric energy density. Higher energy density means the cell can store more electrical energy per unit volume or mass, which is crucial for applications such as portable electronic devices and electric vehicles. How is the energy density of a battery cell calculated? The energy density of a battery cell, i.e., the energy stored per unit volume or unit mass of the battery, is one of the key indicators for measuring battery performance. It is influenced by a variety of complex factors, spanning a wide range of fields from materials science to engineering design. First, the chemical composition of the cell is the core factor affecting energy density. Different cathode materials, such as lithium cobalt oxide (LiCoO2), lithium nickel cobalt manganese oxide (NCM), or lithium iron phosphate (LFP), have different energy storage capacities. Anode materials, such as graphite or silicon-based materials, also affect the overall energy density due to their different electrochemical properties. The choice of electrolyte and the material of the separator are equally important, as they determine the efficiency and safety of ion transport within the battery. Design and manufacturing processes are also crucial factors affecting energy density. The battery's structural design, including electrode thickness, active material loading, and packaging method, significantly impacts energy density. For example, thinner electrodes reduce the use of inactive materials, thus increasing energy density per unit volume. The precision of the manufacturing process, such as coating uniformity, compaction density, and assembly accuracy, all affect battery performance. Furthermore, material quality and purity also have a significant impact on energy density. High-purity materials reduce internal side reactions and improve energy utilization. The microstructure of materials, such as particle size and distribution, also affects the surface area of ​​electrode materials and ion diffusion paths, thereby influencing the battery's charge and discharge performance.

[0038] Lithium plating in batteries refers to the uneven deposition of lithium ions on the surface of the negative electrode during battery charging, eventually forming lithium metal dendrites. The appearance of these dendrites poses a significant threat to the health of the battery. First, from a safety perspective, the growth of lithium dendrites is a double-edged sword. It can not only pierce the battery's internal separator, causing direct contact between the positive and negative electrodes, but this contact often has catastrophic consequences. Once a short circuit occurs, the internal temperature of the battery will rise sharply, triggering a series of chain reactions, potentially leading to overheating, expansion, or even fire and explosion, posing a significant safety hazard to users. Second, the battery's lifespan will be significantly reduced due to the formation of lithium dendrites. The continuous growth of lithium dendrites consumes the battery's precious lithium-ion resources. As the number of lithium ions decreases, the number of rechargeable cycles and the battery's capacity will gradually decline. Users will find that a battery that could have lasted for several years may experience significant performance degradation in a very short time. Furthermore, the battery's charging and discharging efficiency will also be severely affected. The formation of lithium dendrites increases the internal resistance of the battery, making the flow of electrons within the battery less smooth. This increased resistance not only reduces charging speed but also affects power output during discharge, thus lowering the overall battery performance. Finally, the stability of battery performance is also affected by the uneven growth of lithium dendrites. The growth of lithium dendrites can lead to voltage instability during battery use. These voltage fluctuations directly affect the devices powered by the battery, causing them to operate unstably or even shut down unexpectedly. Therefore, lithium plating is a phenomenon that must be strictly controlled and avoided in the design and use of lithium-ion batteries. Battery manufacturers and researchers have been working to reduce or eliminate lithium dendrite formation by improving battery materials, optimizing battery structure, and optimizing charging strategies to ensure battery safety, extend its lifespan, and maintain its performance stability and reliability.

[0039] The embodiments of the present utility model have been described in detail above with reference to the accompanying drawings. However, the present utility model is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present utility model.

Claims

1. An electric cell, characterized by, The application relates to a lithium ion battery, which comprises a positive electrode sheet, a diaphragm and a negative electrode sheet, the positive electrode sheet, the diaphragm and the negative electrode sheet are sequentially stacked and wound to form a battery cell, the battery cell comprises a bending area and a flat area, the positive electrode sheet, the diaphragm and the negative electrode sheet have a bending curvature in the bending area, the positive electrode sheet, the diaphragm and the negative electrode sheet are arranged flatly in the flat area, the positive electrode sheet comprises a bending section and a flat section, the bending section is located in the bending area, and the flat section is located in the flat area. A rubber paper is arranged between the positive electrode sheet and the negative electrode sheet, and the rubber paper corresponds to the bending section, a through hole is formed in the rubber paper and used for passing lithium ions, and the rubber paper is a deformable material. The thickness of the rubber paper in a first direction is not less than 10 um and not more than 20 um, and the first direction is the thickness direction of the positive electrode sheet.

2. The electric cell of claim 1, wherein, The aperture of the through hole is not less than 0.1 um and not more than 0.3 um.

3. The electric cell of claim 1, wherein, The rubber paper is arranged between the positive electrode sheet and the diaphragm and adhered to the bending section.

4. The electric cell of claim 1, wherein, The width direction of the positive electrode sheet is a second direction, and the width of the rubber paper in the second direction is not more than the width of the positive electrode sheet.

5. The electric cell of claim 1, wherein, The positive electrode sheet has a first edge and a second edge in the second direction, and the rubber paper is arranged between the first edge and the second edge, and the distance between the rubber paper and the first edge and the second edge is not more than 50 um.

6. The electric cell of claim 5, wherein, The length of the rubber paper on the positive electrode sheet of the first layer of the battery cell in a third direction is L, the third direction is the extension direction of the positive electrode sheet, the thickness of the positive electrode sheet is A, the thickness of the negative electrode sheet is B, the thickness of the diaphragm is C, the length of the rubber paper on the positive electrode sheet of the Nth layer of the battery cell in the third direction is S, and S=L+pi*[(N-1)*(A+B+2C)] / 2.

7. The electric cell of claim 1, wherein, The positive electrode sheet has two bending sections in the same layer, the rubber paper is arranged on the two bending sections, and the lengths of the rubber papers arranged on the bending sections in the same layer are equal.

8. The electric cell of claim 7, wherein, The rubber paper is an elastically deformable material.

9. The electric cell of claim 1, wherein, The application further relates to a battery comprising the battery cell.

10. A battery, characterized by The application further relates to a battery comprising the battery cell.

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