Lithium ion cell and lithium ion battery

Abstract

The invention relates to the technical field of batteries, particularly provides a lithium ion battery cell and a lithium ion battery, and aims to solve the problem that the cost is increased when the service life of an existing battery is prolonged. In order to achieve the purpose, the lithium ion battery cell comprises a positive pole piece provided with a positive pole lug, a negative pole piece provided with a negative pole lug, the positive pole lug and the negative pole lug are located on the same side in the width direction of the negative pole piece, and the side edge of the pole lug of the negative pole piece exceeds the side edge of the pole lug of the positive pole piece in the width direction of the negative pole piece to form a suspension area; the edge of one side, far away from the positive tab, of the positive plate exceeds the edge of one side, far away from the negative tab, of the negative plate to form a first lithium storage region; an insulating layer is arranged on the end surface of one side, far away from the negative tab, of the negative plate in the width direction of the negative plate, and is used for insulating the end surface of the edge of the negative plate from electrons and ions. The lithium battery is simple in structure, the cost can be reduced while the service life of the battery is prolonged, and the defects of a lithium supplement agent or a composite technology are avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and specifically provides a lithium ion cell and a lithium ion battery. Background Art

[0002] The life cycle cost per kilowatt-hour (LCOS) determines the economic feasibility of energy storage products. This parameter is obtained by dividing the input cost of the entire life cycle by the total discharge volume of the entire life cycle. Reducing the input cost and increasing the life span will significantly reduce the LCOS of energy storage products. Currently, the main ways to increase battery life are to replenish lithium at the positive electrode, replenish lithium at the negative electrode, or over-allocate capacity, but these strategies will simultaneously increase the cost of the battery and may not ultimately have a significant effect on reducing LCOS.

[0003] The positive electrode pre-lithiation technology mainly adds some high-gram capacity and low-reversibility positive electrode lithium supplements (mainstream metal oxides such as lithium nickel oxide and lithium iron oxide) to the positive electrode side. This technology only needs to adjust the formation process in manufacturing and is highly compatible with existing production lines. However, these lithium supplements are expensive and will have a large gas production deterioration problem during the formation and subsequent application process. The negative electrode pre-lithiation technology mainly combines metallic lithium with graphite negative electrode (lithium strip rolling or lithium powder coating) to achieve lithium supplementation. However, because metallic lithium is highly active and reacts violently with moisture in the air, it usually needs to be produced in an ultra-low humidity environment with a dew point of -50°C. It is difficult to manufacture and has a high risk of fire.

[0004] Accordingly, the art needs a new technical solution to solve the above problems. Summary of the invention

[0005] The present invention aims to solve the above technical problems, that is, to solve the problem that the cost of existing batteries increases while the service life increases. To this end, the present invention provides a lithium-ion battery cell, comprising: a positive electrode sheet and a negative electrode sheet, the positive electrode sheet is provided with a positive electrode tab, the negative electrode sheet is provided with a negative electrode tab, the positive electrode tab and the negative electrode tab are located on the same side along the width direction of the negative electrode sheet, and the tab side edge of the negative electrode sheet exceeds the tab side edge of the positive electrode sheet along the width direction of the negative electrode sheet to form an overhanging area; the edge of the positive electrode sheet away from the positive electrode tab exceeds the edge of the negative electrode sheet away from the negative electrode tab to form a first lithium storage area; an insulating layer is provided on the end face of the negative electrode sheet away from the negative electrode tab along the width direction of the negative electrode sheet, and the insulating layer is used to insulate the end face of the edge of the negative electrode sheet from electrons and ions.

[0006] In the above specific embodiment with lithium-ion battery cells, the width of the positive electrode sheet is Dc, the thickness of the first lithium storage area in the width direction of the positive electrode sheet is ΔD, and a% is the improvement of the life of the first lithium storage area, wherein, .

[0007] In the above specific embodiment with lithium-ion battery cells, the improvement rate a% of the life of the first lithium storage area is in the range of 0.5%≤a%≤10%.

[0008] In the above specific embodiment with lithium ion battery cells, the thickness of the insulating layer along the width direction of the negative electrode sheet is between 0.05 μm and 100 μm.

[0009] In the above specific embodiment with lithium ion battery cell, the battery cell further comprises: a diaphragm, the diaphragm is arranged between the positive electrode sheet and the negative electrode sheet, and the diaphragm exceeds the edge of the negative electrode sheet along its length direction and width direction.

[0010] In the above specific embodiment with lithium ion battery cells, the battery cells are wound battery cells.

[0011] In the above specific embodiment with lithium ion battery cells, the battery cells are laminated battery cells.

[0012] In the above-mentioned specific embodiment with a lithium-ion battery cell, along the length direction of the positive electrode sheet, the edge of at least one end face of the positive electrode sheet exceeds the edge of the corresponding end face of the negative electrode sheet to form a second lithium storage area; along the length direction of the negative electrode sheet, a second insulating layer is provided on the end face of the negative electrode sheet on the same side as the second lithium storage area, and the second insulating layer is used to insulate the end face from electrons and ions.

[0013] In the above specific embodiment with lithium-ion battery cells, the length of the positive electrode sheet is Da, the thickness of the second lithium storage area in the length direction of the positive electrode sheet is d, and b% is the improvement of the life of the second lithium storage area, wherein, .

[0014] A lithium ion battery comprises any of the lithium ion cells described above.

[0015] In the case of adopting the above technical solution, the present invention removes the overhang area (i.e., overhang) on ​​the negative electrode sheet away from the negative electrode ear side to prevent the lithium ions that migrate into the overhang area from participating in the charging and discharging process, thereby reducing the loss of lithium ions / active lithium. The first lithium storage area on the positive electrode sheet slowly releases the active lithium through the principle of the electrolytic cell, and transfers it to the negative electrode through the diaphragm by means of particle diffusion, so as to supplement the negative electrode sheet with lithium and improve the battery cycle life. In addition, the part of the positive electrode sheet that overlaps with the negative electrode sheet is the overlapping area, and the lithium ions in the first lithium storage area can diffuse into the overlapping area in the solid phase, which is equivalent to storing a part of lithium in the first lithium storage area in advance, and can be subsequently supplied to the overlapping area for charging and discharging, thereby extending the battery life. The present invention has a simple structure, can reduce the cost of improving the battery life, and will not have the dangers and defects brought by lithium supplements or composite technologies. For stacked batteries, along the length direction of the positive electrode sheet, the edges of the two end faces of the positive electrode sheet respectively exceed the edges of the corresponding two end faces of the negative electrode sheet to form two second lithium storage areas; a second insulating layer is respectively provided on the two end faces of the negative electrode sheet along the length direction; this can increase the area of ​​the lithium storage area and further improve the battery life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which: Figure 1 is a top view of the wound battery cell of the present invention before winding; Figure 2 is a top view of a wound battery cell with a separator placed between a positive electrode sheet and a negative electrode sheet before winding in the present invention; Figure 3 yes Figure 2 Left view in; Figure 4 It is a schematic diagram of the structure of the negative electrode sheet in the present invention; Figure 5 It is a top view of the positive electrode sheet and the negative electrode sheet of the laminated battery cell of the present invention after being overlapped and placed; Figure 6 It is a top view of a stacked battery cell having a separator placed between a positive electrode sheet and a negative electrode sheet in the present invention; Figure 7 yes Figure 6 Schematic diagram of the cross-sectional structure at AA in the middle; Figure 8 It is an experimental data diagram in the present invention.

[0017] In the figure: 1. positive electrode sheet, 2. negative electrode sheet, 3. positive electrode ear, 4. negative electrode ear, 5. overhanging area, 6. first lithium storage area, 7. insulating layer, 8. separator, 9. negative electrode current collector, 10. negative electrode membrane, 11. positive electrode edge insulating layer, 12. overlapping area, 13. second lithium storage area, 14. second insulating layer. DETAILED DESCRIPTION

[0018] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not used to limit the scope of protection of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0019] It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the relevant devices or elements must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, ordinal numbers such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0020] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] Furthermore, in order to more clearly demonstrate the core technical solution of the present invention, the description of the well-known battery structure is omitted in the following description. However, this omission is only for the convenience of description and does not mean that the battery can be without these structures.

[0022] like Figure 1-4 As shown, the present invention proposes a lithium ion battery cell, comprising: a positive electrode sheet 1 and a negative electrode sheet 2, a positive electrode tab 3 is arranged on the positive electrode sheet 1, a negative electrode tab 4 is arranged on the negative electrode sheet 2, the positive electrode tab 3 and the negative electrode tab 4 are located on the same side along the width direction of the negative electrode sheet 2, and the tab side edge of the negative electrode sheet 2 exceeds the tab side edge of the positive electrode sheet 1 along the width direction of the negative electrode sheet 2 to form an overhanging area 5; the edge of the positive electrode sheet 1 away from the positive electrode tab 3 exceeds the edge of the negative electrode sheet 2 away from the negative electrode tab 4 to form a first lithium storage area 6; an insulating layer 7 is arranged on the end face of the negative electrode sheet 2 away from the negative electrode tab 4 along the width direction of the negative electrode sheet 2, and the insulating layer 7 is used to insulate the end face of the negative electrode sheet 2 from electrons and ions. In the figure, the X direction represents the width direction of the positive electrode sheet 1 and the negative electrode sheet 2, and the Y direction represents the length direction of the positive electrode sheet 1 and the negative electrode sheet 2.

[0023] Lithium-ion cells are components in batteries where electrochemical reactions occur. They are mainly formed by winding or stacking a positive electrode sheet 1 and a negative electrode sheet 2, and a separator 8 is usually provided between the negative electrode sheet 2 and the positive electrode sheet 1. The separator 8 is used to separate the positive electrode sheet 1 and the negative electrode sheet 2 and allow the electrolyte to flow through.

[0024] In the prior art, when designing a battery cell, the negative electrode sheet is usually designed to be excessive, so that the negative electrode sheet exceeds the positive electrode sheet in width and length, and the excess portion is called the overhang area (or overhang area) to ensure that the negative electrode has sufficient capacity to accept the lithium ions migrated from the positive electrode, thereby avoiding the occurrence of lithium precipitation to a certain extent. However, the design of the overhang area will reduce the energy density of the battery to a certain extent, and during the charging process, some lithium ions will diffuse into the overhang area of ​​the negative electrode. These lithium ions may not be able to completely return to the positive electrode during the subsequent discharge process and cannot participate in the charging and discharging process, which will reduce the lithium ions / active lithium participating in the charging and discharging reaction, thereby causing battery capacity loss, accelerating the capacity decay of the battery during the cycle process, and reducing the life. In addition, if the overhang area is too large, it will increase the risk of lithium precipitation, causing lithium ions to precipitate electrons on the surface of the negative electrode sheet to form lithium dendrites. Lithium dendrites may pierce the diaphragm and cause a short circuit in the battery, causing thermal runaway, and reducing the safety and life of the battery.

[0025] In this embodiment, in order to solve the problem of increased cost as the battery life increases in the prior art, the structure of the battery assembly is modified. Specifically, the overhang area on the negative electrode sheet 2 away from the negative electrode tab 4 is removed to prevent the lithium ions that migrate into the overhang area from participating in the charging and discharging process, thereby reducing the loss of lithium ions / active lithium. Although the loss of lithium ions can be reduced by only removing the overhang area on the non-tab side of the negative electrode sheet 2, lithium cannot be supplemented to the positive electrode sheet 1 and the negative electrode sheet 2. For this reason, in this embodiment, a first lithium storage area 6 is also provided on the positive electrode sheet 1. The first lithium storage area 6 slowly releases active lithium through the principle of an electrolytic cell, and transfers it to the negative electrode through the diaphragm 8 by means of particle diffusion, so as to supplement lithium to the negative electrode sheet 2, thereby achieving an increase in the battery cycle life.

[0026] In addition, the part of the positive electrode sheet 1 that overlaps with the negative electrode sheet 2 is the overlap area 12 of the positive electrode sheet 1. The lithium ions in the first lithium storage area 6 can be solid-phase diffused to the overlap area 12, which is equivalent to storing a portion of lithium in the first lithium storage area 6 in advance, which can be subsequently supplied to the overlap area 12 for charging and discharging, thereby extending the battery life. The material of the first lithium storage area 6 can be the same as that of the overlap area 12 on the positive electrode sheet 1. It should be pointed out that Figure 1 It is just a schematic diagram of the overlapping state between the positive electrode sheet 1 and the negative electrode sheet 2. Figure 1The overlapping area 12 is only for the convenience of showing the placement status between the positive electrode sheet 1 and the negative electrode sheet 2, and does not limit the area size of the overlapping area 12. Without deviating from the basic principles of the present invention, technicians in this field can adjust the area of ​​the overlapping area 12 according to actual conditions.

[0027] The lithium ions released from the overlapping area 12 can be received by the corresponding part on the negative electrode sheet 2, and lithium deposition will not occur. If the lithium ions released in the first lithium storage area 6 gain electrons at the end face on the non-ear side of the negative electrode sheet 2, lithium deposition will occur. The deposited lithium will grow along the width direction of the negative electrode sheet 2, which will cause the consumption of lithium ions and reduce the battery life. After the lithium dendrites grow in one direction, it will also seriously affect the performance and safety of the battery. In order to avoid lithium deposition at the non-ear side edge of the negative electrode sheet 2, an insulating layer 7 is also provided on the end face of the negative electrode sheet 2 away from the negative electrode ear 4 in this embodiment. The insulating layer 7 is used to insulate the non-ear side end face of the negative electrode sheet 2 along the width direction from electrons and ions to avoid lithium ions from gaining electrons and depositing on this end face.

[0028] like Figure 1 As shown, Figure 1 The middle negative electrode sheet 2 is stacked on the positive electrode sheet 1, and the positive electrode sheet 1 has an overlapping area 12 and a first lithium storage area 6. Figure 1 The area above the negative electrode sheet 2 that exceeds the upper edge of the overlapping area 12 is the overhang area 5, and the dotted line in the figure indicates the range of the overhang area 5. The area below the positive electrode sheet 1 that exceeds the lower edge of the negative electrode sheet 2 is the first lithium storage area 6, and the dotted line in the figure indicates the range of the first lithium storage area 6. It should be pointed out that Figure 1 It is just a schematic diagram of the overlapping state between the positive electrode sheet 1 and the negative electrode sheet 2. Figure 1 The overhanging area 5 and the first lithium storage area 6 are only for the convenience of showing their settings, and are not intended to limit the area sizes of the overhanging area 5 and the first lithium storage area 6. Without departing from the basic principles of the present invention, technical personnel in this field can adjust the areas of the overhanging area 5 and the first lithium storage area 6 according to actual conditions.

[0029] like Figure 1-2 As shown, a positive electrode edge insulating layer 11 is also provided on the side of the overlapping area 12 away from the first lithium storage area 6. The positive electrode edge insulating layer 11 can prevent the positive electrode sheet 1 from short-circuiting with other conductive components, improve the safety performance of the battery, and prevent the positive electrode material from electrochemically reacting with the battery shell or other inactive components, reduce unnecessary energy loss inside the battery, and protect the internal structure and performance of the battery from being damaged.

[0030] It should be pointed out that Figure 1It is only a schematic diagram of the structure of the battery cell in the width direction. In the figure, the lengths of the positive electrode sheet 1 and the negative electrode sheet 2 are quite different. This is just for the convenience of showing the structure of the positive electrode sheet 1 and the negative electrode sheet 2 in the width direction, and is not intended to limit the length relationship between the positive electrode sheet 1 and the negative electrode sheet 2. Without deviating from the basic principles of the present invention, technical personnel in this field can set the lengths of the positive electrode sheet 1 and the negative electrode sheet 2 according to actual conditions.

[0031] A control experiment was conducted using a conventional battery and a battery having the battery cell of the present invention. The experimental data are as follows: Figure 8 As shown, the experimental group uses a battery having the battery cell of the present invention, i.e., a battery cell having a first lithium storage area 6 on the positive electrode sheet 1 and an overhang area 5 and an insulating layer 7 on the negative electrode sheet 2; the control group uses a battery having an existing conventional battery cell, i.e., a battery cell without an overhang area 5 and a first lithium storage area 6. The experiments were all performed at an ambient temperature of 35 degrees Celsius and at 50% of the rated power. Figure 8 The horizontal axis is the number of cycles, and the vertical axis is the capacity retention rate during the cycle. Active lithium will be continuously consumed during the cycle. Since the positive and negative electrode material system designs of the experimental group and the control group are the same, theoretically, the active lithium consumption rate of the experimental group and the control group is the same. Figure 8 It can be seen that the capacity retention rate of the experimental group during the cycle is improved compared with that of the control group during the cycle, indicating that under the same consumption rate, the first lithium storage area 6 of the positive electrode sheet 1 in the experimental group exceeds the negative electrode sheet 2 and continuously replenishes active lithium, which ultimately reflects that the capacity decay rate of the experimental group is slowed down and the cycle performance is improved. Therefore, the present invention has a simple structure and does not require the use of high-cost lithium supplements or composite technologies, which reduces the cost of improving battery life. In addition, the present invention improves the life by improving the structure of the battery cell, and there are no dangers and defects caused by lithium supplements or composite technologies.

[0032] The shape of the first lithium storage area 6 can be a rectangular parallelepiped, and the dimension along the width direction of the positive electrode sheet 1 is the thickness of the first lithium storage area 6. The thickness of the first lithium storage area 6 is uniformly laid on the end surface of the negative electrode sheet 2. The first lithium storage area 6 and the positive electrode sheet 1 can be formed in one step. Furthermore, the width of the positive electrode sheet 1 is Dc, and the width of the first lithium storage area 6 is △D. In order to increase the life by different degrees, the required thickness of the first lithium storage area 6 is different. Therefore, the thickness of the first lithium storage area 6 in the width direction of the positive electrode sheet 1 is , a% is the improvement of the life of the first lithium storage area 6. In order not to make the first lithium storage area 6 too wide, the value range of the improvement of the life of the first lithium storage area 6 a% is: 0.5%≤a%≤10%. In the above control experiment, the improvement of the life a% is 3%.

[0033] It should be pointed out that Figure 1The width of the first lithium storage area 6 is for illustration only and is not a limitation of the present invention. Without departing from the basic principles of the present invention, those skilled in the art can select the extent of the required life improvement according to actual conditions and adopt the corresponding width of the first lithium storage area 6.

[0034] The shape of the insulating layer 7 can be a rectangular parallelepiped, and its dimension in the width direction of the negative electrode sheet 2 is the thickness of the insulating layer 7. The thickness of the insulating layer 7 is uniformly laid on the end surface of the negative electrode sheet 2. Furthermore, the thickness of the insulating layer 7 along the width direction of the negative electrode sheet 2 is between 0.05 μm and 100 μm, which can ensure the insulation effect and avoid the failure of the insulating layer 7. The insulating layer 7 can be realized by gluing, coating, spraying, etc., as long as it has the dual characteristics of electronic and ionic insulation. It should be pointed out that Figure 1 The ratio of the thickness of the middle insulating layer 7 along the width direction of the negative electrode sheet 2 to the width of the negative electrode sheet 2 is for illustration only and is not a limitation of the present invention. Without departing from the basic principles of the present invention, those skilled in the art can adjust the thickness of the insulating layer 7 along the width direction of the negative electrode sheet 2 according to actual conditions.

[0035] Further, if Figure 2 and Figure 3 As shown, the battery cell further includes: a separator 8, which is disposed between the positive electrode sheet 1 and the negative electrode sheet 2. In order to separate the positive electrode sheet 1 from the negative electrode sheet 2 and allow the electrolyte to flow through, the separator 8 exceeds the edge of the negative electrode sheet 2 in both its length and width directions. Figure 2 The negative electrode sheet 2 is stacked on top of the separator 8 , and the separator 8 is stacked on top of the positive electrode sheet 1 . Figure 3 FIG. 4 shows the positional relationship among the positive electrode sheet 1 , the separator 8 and the negative electrode sheet 2 from another perspective.

[0036] Further, if Figure 4 As shown, the negative electrode sheet 2 includes: a negative electrode current collector 9 , a negative electrode tab 4 connected to one end of the negative electrode current collector 9 ; and a negative electrode membrane 10 , which is disposed on at least one side of the negative electrode current collector 9 . Figure 4 The negative electrode film 10 is arranged on the upper and lower sides of the negative electrode current collector 9. Figure 4 As shown, the insulating layer 7 covers the entire end surface of the negative electrode current collector 9 and the negative electrode membrane 10 .

[0037] Furthermore, the battery cell is a wound battery cell. The manufacturing process of the wound battery is as follows: after stacking the positive electrode sheet 1, the separator 8 and the negative electrode sheet 2 in the battery cell in order, these materials are directly rolled into a cylindrical or elliptical cylindrical shape by winding with a fixed winding needle, and then the wound battery cell is placed in a square or cylindrical metal shell to complete the packaging to form a wound battery.

[0038] Furthermore, the battery cell is a laminated battery cell. The manufacturing process of the laminated battery is as follows: stack the positive electrode sheet 1, the separator 8 and the negative electrode sheet 2 in the battery cell in order to form a unit, and then stack multiple units in sequence to form a battery cell that can be packaged, and finally package and cut the battery cell into a laminated battery.

[0039] Furthermore, for the laminated battery cell, along the length direction of the positive electrode sheet 1, the edge of at least one end face on the positive electrode sheet 1 exceeds the edge of the corresponding end face on the negative electrode sheet 2 to form a second lithium storage area 13; along the length direction of the negative electrode sheet 2, a second insulating layer 14 is provided on the end face of the negative electrode sheet 2 on the same side as the second lithium storage area 13, and the second insulating layer 14 is used to insulate the end face from electrons and ions to prevent lithium ions from obtaining electrons and precipitating on the end face. The materials of the first lithium storage area 6 and the second lithium storage area 13 can be the same or different; the materials of the insulating layer 7 and the second insulating layer 14 can be the same or different; the "second" here is only used to distinguish the description and cannot be understood as indicating or implying relative importance. The second lithium storage area 13 increases the area of ​​the lithium storage area on the electrode sheet, further improving the battery life.

[0040] like Figure 5-Figure 7 As shown, along the length direction of the positive electrode sheet 1, the edges of the two end faces of the positive electrode sheet 1 respectively exceed the edges of the two corresponding end faces of the negative electrode sheet 2, forming two second lithium storage areas 13; the two end faces of the negative electrode sheet 2 along its length direction are respectively provided with a second insulating layer 14 to prevent lithium ions from obtaining electrons and precipitating on the two end faces.

[0041] In addition, it is also possible to make only the edge of the end face on one side of the length direction of the positive electrode sheet 1 exceed the corresponding end face edge on the negative electrode sheet 2, that is, to form only one second lithium storage area 13. This can also further increase the area of ​​the lithium storage area on the electrode sheet. Similarly, it is only necessary to set the second insulating layer 14 on the end face on the negative electrode sheet 2 on the same side as the second lithium storage area 13 along the length direction of the negative electrode sheet. For example, the second lithium storage area 13 is formed only on the left side of the positive electrode sheet 1, and the second insulating layer 14 is set on the left end face of the negative electrode sheet 2. This does not deviate from the principle of the present invention and therefore falls within the protection scope of the present invention.

[0042] Figure 5 The negative electrode sheet 2 is stacked on top of the positive electrode sheet 1. Figure 5 The area above the middle negative electrode sheet 2 and beyond the upper edge of the overlapping area 12 is the overhang area 5. Figure 5 The dotted line in the figure indicates the range of the overhanging area 5 , and the area below the positive electrode sheet 1 that exceeds the lower edge of the negative electrode sheet 2 and the area beyond the negative electrode sheet 2 in the length direction of the positive electrode sheet 1 are the first lithium storage area 6 . Figure 6 The negative electrode sheet 2 is stacked on the top of the separator 8, and the separator 8 is stacked on the top of the positive electrode sheet 1. Figure 7FIG. 1 shows the positional relationship among the positive electrode sheet 1 , the separator 8 and the negative electrode sheet 2 from another perspective, and the range of the second lithium storage area 13 and the second insulating layer 14 are shown by dotted lines.

[0043] Furthermore, the length of the positive electrode sheet 1 is Da, the thickness of the second lithium storage area 13 in the length direction of the positive electrode sheet 1 is d, and b% is the improvement of the life of the second lithium storage area 13, wherein, In general, the life improvement range b% is 0.5%≤a%≤10%. In the present invention, the life improvement range a% and the life improvement range b% are both based on the battery cell without the first lithium storage area 6 and the second lithium storage area 13 as the basic object for calculating the life improvement range.

[0044] For laminated batteries, if you want to increase the battery life by b% over the original life on the basis that the first lithium storage area 6 can increase the battery life by a%, that is, a total increase of (a%+b%), you can form a second lithium storage area 13 on the positive electrode sheet 1, and the thickness of the second lithium storage area 13 is calculated according to the above formula; you can also form two second lithium storage areas 13 on the positive electrode sheet 1. Since two second lithium storage areas 13 are set, each second lithium storage area 13 will increase the battery life, so it is necessary to replace b% in the above formula with (b / 2)% to calculate the thickness of the two second lithium storage areas 13, so that the sum of the battery life improvement of the two second lithium storage areas 13 is equal to b%. In general, 0.5%≤(a%+b%)≤10%.

[0045] For example, if the first lithium storage area 6 can increase the life of the battery cell by 3%, and if you want to increase the life of the battery cell by 2%, that is, a total increase of 5%, then you can form a second lithium storage area 13 on the positive electrode sheet 1. The thickness of the second lithium storage area 13 is calculated according to the above formula, that is, Two second lithium storage areas 13 may also be formed on the positive electrode sheet 1. In this case, the thickness calculation formula of the second lithium storage area 13 is: , thus the sum of the improvements in battery life caused by the two second lithium storage areas 13 is equal to 2%.

[0046] If the first lithium storage area 6 on the positive electrode sheet 1 is too large, it will also bring negative effects, such as affecting the energy density of the battery cell. The existence of the second lithium storage area 13 in this embodiment allows the thickness of the first lithium storage area 6 to be adjusted more flexibly, as long as the sum of the effect of the first lithium storage area 6 on improving the battery life and the effect of the second lithium storage area 13 on improving the battery life reaches the preset requirements.

[0047] It should be pointed out that Figure 5-Figure 6 The size of the second lithium storage area 13 in the length direction of the positive electrode sheet 1 is the thickness of the second lithium storage area 13. Figure 5-Figure 6The thickness of the second lithium storage area 13 is only for illustration and is not intended to limit the present invention. Without departing from the basic principles of the present invention, those skilled in the art may select the extent of life improvement according to actual conditions and adopt different thicknesses of the second lithium storage area 13. Figure 5-Figure 6 The dimension of the second insulating layer 14 in the length direction of the negative electrode sheet 2 is the thickness of the second insulating layer 14. Figure 5-Figure 6 The thickness of the second insulating layer 14 is for illustration only and is not intended to limit the present invention. Without departing from the basic principles of the present invention, those skilled in the art may adjust the thickness of the second insulating layer 14 according to actual conditions.

[0048] The present invention also provides a lithium ion battery (not shown in the figure). The battery includes the lithium ion battery cell of any of the above embodiments. The battery can be, but is not limited to, a battery in a laptop computer, a tablet computer, a smart phone, an electric car, etc.

[0049] Those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims of the present application, any one of the claimed embodiments may be used in any combination.

[0050] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A lithium-ion battery cell, characterized in that: include: A positive electrode sheet (1) and a negative electrode sheet (2), wherein the positive electrode sheet (1) is provided with a positive electrode tab (3), and the negative electrode sheet (2) is provided with a negative electrode tab (4), the positive electrode tab (3) and the negative electrode tab (4) are located on the same side along the width direction of the negative electrode sheet (2), and along the width direction of the negative electrode sheet (2), the tab side edge of the negative electrode sheet (2) exceeds the tab side edge of the positive electrode sheet (1) to form an overhanging area (5); An edge of the positive electrode sheet (1) away from the positive electrode tab (3) extends beyond an edge of the negative electrode sheet (2) away from the negative electrode tab (4) to form a first lithium storage area (6); An insulating layer (7) is provided on the end surface of the negative electrode sheet (2) on the side away from the negative electrode tab (4) along the width direction of the negative electrode sheet (2), and the insulating layer (7) is used to insulate the end surface of the negative electrode sheet (2) from electrons and ions.

2. The lithium-ion battery cell according to claim 1, characterized in that: The width of the positive electrode sheet (1) is Dc, the thickness of the first lithium storage area (6) in the width direction of the positive electrode sheet (1) is ΔD, and a% is the improvement of the life of the first lithium storage area (6), wherein: .

3. The lithium-ion battery cell according to claim 2, characterized in that: The range of the improvement of the lifespan by the first lithium storage area (6) is 0.5%≤a%≤10%.

4. The lithium-ion battery cell according to claim 1, characterized in that: The thickness of the insulating layer (7) along the width direction of the negative electrode sheet (2) is between 0.05 μm and 100 μm.

5. The lithium-ion battery cell according to claim 1, characterized in that: The battery cell also includes: A diaphragm (8), the diaphragm (8) being arranged between the positive electrode sheet (1) and the negative electrode sheet (2), the diaphragm (8) extending beyond the edge of the negative electrode sheet (2) in both its length direction and width direction.

6. The lithium-ion battery cell according to any one of claims 1 to 5, characterized in that: The battery core is a wound battery core.

7. The lithium-ion battery cell according to any one of claims 1 to 5, characterized in that: The battery core is a laminated battery core.

8. The lithium-ion battery cell according to claim 7, characterized in that: Along the length direction of the positive electrode sheet (1), the edge of at least one end surface of the positive electrode sheet (1) exceeds the edge of the corresponding end surface of the negative electrode sheet (2) to form a second lithium storage area (13); Along the length direction of the negative electrode sheet (2), a second insulating layer (14) is provided on the end surface of the negative electrode sheet (2) located on the same side as the second lithium storage area (13), and the second insulating layer (14) is used to insulate the end surface from electrons and ions.

9. The lithium-ion battery cell according to claim 8, characterized in that: The length of the positive electrode sheet (1) is Da, the thickness of the second lithium storage area (13) in the length direction of the positive electrode sheet (1) is d, and b% is the improvement of the life of the second lithium storage area (13), wherein: .

10. A lithium ion battery, characterized in that: The lithium-ion battery comprises the lithium-ion battery cell according to any one of claims 1 to 9.

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