Quick charging core, lithium ion battery and electric product

Abstract

The utility model discloses a fast charging core, a lithium ion battery and an electric product, and relates to the technical field of new energy. According to the fast charging core provided by the utility model, the positive electrode coating gap is arranged on the positive electrode, the negative electrode coating gap is arranged on the negative electrode, and the arrangement positions of the positive electrode coating gap and the negative electrode coating gap are optimized, so that the lithium ion receiving capability of the negative electrode is improved, and the increase amplitude of side reaction is reduced as much as possible; and the pressure at the corner is relieved, and the rate capability and the cycle performance of the fast charging core are finally improved. The utility model also provides a lithium ion battery comprising the quick charging core and an electric product.

Description

Technical Field

[0001] The utility model relates to the technical field of new energy, and in particular to a fast charging cell, a lithium-ion battery and an electric product. Background Art

[0002] Lithium-ion batteries are widely used in the digital and power battery fields due to their high energy density. As digital products and power batteries increasingly demand higher energy density and fast-charging rates, the areal and compaction densities of lithium-ion battery cells are being increased. This results in increasing pressure on the corners of the cells during the charge and discharge process. As the pressure compresses, the electrolyte in the corners is gradually squeezed out, eventually causing the bridge to break at the corners.

[0003] Lithium deposition at the corners of the battery cell starts from the inner layer, and gradually spreads to the outer layer as the inner layer becomes heavier. Taking the center-placed tab structure as an example, the lithium deposition at the corners is most serious at the corner of the anode corresponding to the pole piece where the cathode tab is located, and then gradually becomes lighter. Generally, it gradually becomes heavier with the increase in the number of cycles until it spreads to the entire pole piece.

[0004] With the introduction of silicon-based negative electrode materials into batteries, lithium deposition at the corners of lithium-ion battery cells has become increasingly severe, and the onset of this problem is also becoming earlier and earlier. This is related to the rapid consumption of electrolyte in the silicon system. Studies have also shown that using laser drilling on the negative electrode to increase the electrolyte retention capacity will destroy the structure of the silicon-based negative electrode material, expose highly active substances, increase side reactions, and accelerate electrolyte consumption. At the same time, the volume of the negative electrode expands too much, and the pressure on the corners is greater, leading to increased lithium deposition at the corners. In other words, although conventional lithium-ion battery cells also have the problem of lithium deposition at the corners, the situation is more serious in fast-charging cells containing silicon-based negative electrode materials. Conventional drilling methods are difficult to alleviate and may degrade performance.

[0005] In summary, the problem of lithium deposition in the corners of silicon-based fast-charging cells is serious, and the solutions provided in related technologies have very limited effects. Utility Model Content

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a fast-charging cell that improves the fast-charging performance of a high-energy-density cell.

[0007] The utility model also provides a lithium ion battery whose preparation raw materials include the above-mentioned fast charging core.

[0008] The utility model also proposes an electric product whose raw materials include the above-mentioned fast charging core.

[0009] According to the first embodiment of the present invention, the fast charging cell is formed by winding a positive electrode, a separator and a negative electrode; the separator is provided between the positive electrode and the negative electrode; the negative electrode includes a negative electrode current collector, a negative electrode coating provided on the surface of the negative electrode current collector, and a central negative electrode tab electrically connected to the negative electrode current collector; the positive electrode includes a positive electrode current collector, a positive electrode coating provided on the surface of the positive electrode current collector, and a central positive electrode tab electrically connected to the positive electrode current collector;

[0010] Starting from the positive electrode tab, a positive electrode coating notch is provided on the positive electrode coating at a corner of the fast charging cell;

[0011] A negative electrode coating notch is provided on the negative electrode coating around the projection position of the positive electrode tab on the negative electrode.

[0012] The fast charging cell according to the embodiment of the present invention has at least the following beneficial effects:

[0013] The fast charging cell provided by the utility model adopts a design of local perforation of the positive and negative electrodes to achieve precise control of dynamics. Specifically:

[0014] For a fast-charging cell with the tab in the middle, during the charging phase, the current density near the positive tab or its projection on the negative electrode surface is the largest. Therefore, the positive electrode coating notch of the utility model is arranged around the positive tab, and the negative electrode coating notch is arranged around the projection of the positive tab on the negative electrode surface, which can effectively solve the problem of insufficient charging and improve the fast charging performance.

[0015] For wound-type fast-charging cells, if the negative electrode has a poor ability to accept lithium ions, lithium plating will occur; during charging, the entire surface of the negative electrode accepts lithium ions, and the ability of the entire surface to accept lithium ions needs to be improved. Therefore, the negative electrode coating gap is set on the entire surface around the projection position of the positive electrode ear on the negative electrode surface; and the corners are subject to long-cycle extrusion and electrolyte consumption, so the positive electrode coating gap is only set around the positive electrode ear at the corner.

[0016] According to the above description, the solution provided by the present invention sets as few positive electrode coating gaps or negative electrode coating gaps as possible on the basis of ensuring charging performance.

[0017] According to some embodiments of the present invention, the total number of winding layers N of the fast charging cell ranges from 10 to 50. For example, it can be 11 layers, 12 layers, 13 layers, 15 layers, 20 layers, 25 layers, 30 layers or 40 layers. The relationship between the number of layers and the number of corners is that the number of corners = N+1; for example, if N=1, the number of corners is 2; if N=10, the number of corners of the fast charging cell is 11. The subsequent calculation of the corner position of the positive or negative electrode punching is based on the negative electrode on the opposite side of the positive electrode tab as the starting calculation layer, and the number of corners added each time is 2, that is, each layer is increased by 1 on both sides each time.

[0018] According to some embodiments of the present invention, the positive electrode coating gap is a continuous solid line gap.

[0019] According to some embodiments of the present invention, at each corner, the positive electrode coating is provided with one or more parallel solid line notches (also called grooves), for example, 3, 4, 5, 6, 7 or 8 notches.

[0020] According to some embodiments of the present invention, the width of the positive electrode coating gap is 20 to 80 μm. For example, it can be about 50 μm or about 60 μm. This width refers to the width of the solid or dashed gap. For an explanation of the width of the negative electrode coating gap, please refer to here.

[0021] According to some embodiments of the present invention, at each corner, the distance between two adjacent solid line notches is 1 to 2 mm.

[0022] According to some embodiments of the present invention, the depth of the notch in the positive electrode coating is 1 / 4 to 2 / 3 of the thickness of the positive electrode coating, for example, about 30%, 40%, 50% or about 60%.

[0023] If the notch in the positive electrode coating is a dotted notch, the depth here is the drilling depth, that is, the deepest depth of the dotted notch. For the depth of the notch in the negative electrode coating, refer to the explanation here.

[0024] According to some embodiments of the present invention, the thickness of the positive electrode coating is 20-100 μm, for example, about 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm or about 90 μm.

[0025] According to some embodiments of the present invention, the negative electrode coating gap is a continuous solid line gap, or a dotted line gap formed by connecting pore structures.

[0026] When the negative electrode coating gaps are solid line gaps, the distance between two adjacent solid line gaps is 1 to 2 mm, for example, about 1.5 mm.

[0027] When the negative electrode coating gap is a dotted line gap, that is, the pore structure perpendicular to the negative electrode coating is arranged in an array at the position where the negative electrode coating gap is required.

[0028] According to some embodiments of the present invention, the width of the gap in the negative electrode coating is 30 to 120 μm, for example, about 50 μm, 80 μm, or about 100 μm.

[0029] According to some embodiments of the present invention, the depth of the notch in the negative electrode coating is 1 / 4 to 2 / 3 of the thickness of the negative electrode coating, for example, about 30%, 40%, 50% or about 60%.

[0030] According to some embodiments of the present invention, the thickness of the negative electrode coating is 40-120 μm, for example, about 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or about 110 μm.

[0031] According to some embodiments of the present invention, the positive electrode coating notch extends through or across the positive electrode coating; and / or the negative electrode coating notch extends through or across the negative electrode coating. According to some embodiments of the present invention, the total number of wound layers of the fast charging cell is N, the number of wound layers in which the positive electrode coating notch exists is n, and 1≤n≤N / 2. For example, it can be approximately 2, 3N / 10, or N / 4.

[0032] Setting at least one positive electrode coating gap is useful, so the lower limit is set to 1; if more positive electrode coating gaps are set, the side reaction ratio will increase, so the upper limit is set to N / 2.

[0033] According to some embodiments of the present invention, the fast charging cell satisfies the relationship 3≤n≤N / 3, for example, 3N / 20.

[0034] According to some embodiments of the present invention, the total number of winding layers of the fast charging core is N, the number of winding layers with the negative electrode coating gap is m; and 3≤m≤N / 2.

[0035] The lower limit of 3 in the above range is set to accommodate small-capacity fast-charging cells, such as those with only 6 or 10 layers. To match the positive electrode and achieve fast-charging performance, gaps in the negative electrode coating must be provided in at least three layers. The upper limit is set to control the proportion of side reactions to a certain extent.

[0036] According to some embodiments of the present invention, the fast charging cell satisfies the relationship 3≤m≤n+1.

[0037] According to some embodiments of the present invention, the raw materials for preparing the negative electrode coating include silicon-based negative electrode materials. Compared with other types of fast-charging cells, fast-charging cells containing silicon-based negative electrode materials have their own particularities; specifically, silicon-based negative electrode materials consume electrolyte faster than other negative electrode materials. If no holes are punched (i.e., coating gaps are set), the electrolyte content is low, and lithium deposition at the corners is serious. If holes are not punched properly, the consumption of the electrolyte is further accelerated, which will still lead to lithium deposition at the corners. The fast-charging cell provided by the present invention adjusts the position of the coating gaps on the positive and negative electrodes, as well as the amount of the coating gaps, etc., destroys the structure of the silicon-based negative electrode material as little as possible, effectively balances the relationship between the electrolyte retention amount and the electrolyte consumption, and can significantly improve the fast-charging performance and fast-charging cycle performance of the fast-charging cell containing silicon-based negative electrode materials.

[0038] According to some embodiments of the present invention, in the fast charging cell, the positive electrode tab and the negative electrode tab are staggered, thereby preventing the positive electrode tab and the negative electrode tab from contacting each other, thereby avoiding short circuit problems during storage, transportation, and use.

[0039] According to the above description, the fast charging cell provided by the present invention adopts a design of local perforation of the positive and negative electrodes, which realizes precise control of dynamics, ensures that there are holes at positions with higher charging current density of the fast charging cell, solves the problem of insufficient charging, and at the same time does not punch holes in places with low charging current density, avoids damage to the active materials of the positive and negative electrodes, especially the silicon-based negative electrode materials, reduces the side reactions of the fast charging cell, and thus reduces the overall expansion of the fast charging cell during use; and optimizes the cycle performance of the fast charging cell.

[0040] According to the lithium-ion battery of the embodiment of the second aspect of the present invention, the lithium-ion battery includes the fast-charging cell and an electrolyte that soaks the fast-charging cell.

[0041] The lithium-ion battery according to the embodiment of the present utility model (utility model) has at least the following beneficial effects:

[0042] The rate performance and cycle performance are significantly improved.

[0043] According to some embodiments of the present invention, the lithium-ion battery further includes a battery case; the battery case accommodates the fast charging cell and the electrolyte.

[0044] According to some embodiments of the present invention, the electrolyte comprises a lithium salt and an organic solvent.

[0045] The lithium salt includes at least one of LiPF6, LiClO4, LiBF4, LiBOB and LiAsF6.

[0046] The concentration of the lithium salt in the electrolyte is 0.5 to 2 mol / L, for example, about 1 mol / L or about 1.5 mol / L.

[0047] The organic solvent includes at least one of ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC) and propyl propionate (PP).

[0048] According to the electric product of the embodiment of the third aspect of the present utility model, the raw materials for preparing the electric product include the fast charging cell or the lithium-ion battery.

[0049] According to some embodiments of the present invention, the electric product includes at least one of a digital product and a new energy vehicle, wherein the digital product includes at least one of a mobile phone, a tablet computer, a camera, and a laptop computer.

[0050] Unless otherwise specified, the term “about” in the present invention means that the allowable error is within the range of ±2%. For example, about 100 is actually 100±2%×100.

[0051] Unless otherwise specified, “between” in the present invention includes the number itself, for example, “between 2 and 3” includes the endpoint values ​​2 and 3.

[0052] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0054] Figure 1 This is a schematic structural diagram of the positive electrode (upper) and the negative electrode (lower) used in one embodiment of the present invention.

[0055] Figure Number:

[0056] Positive electrode current collector 110, positive electrode coating 120, positive electrode coating notch 121, positive electrode tab 130, tape 140;

[0057] Negative electrode current collector 210 , negative electrode coating 220 , negative electrode coating notch 221 , negative electrode tab 230 . DETAILED DESCRIPTION

[0058] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0059] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0060] Example 1

[0061] Reference Figure 1 As shown, this example provides a fast charging cell, which is formed by winding a positive electrode, a separator and a negative electrode, with 20 winding layers; the separator is provided between the positive electrode and the negative electrode;

[0062] refer to Figure 1 (Top) The positive electrode used in this example includes a positive electrode collector 110, a positive electrode coating 120 provided on the surface of the positive electrode collector 110, and a central positive electrode tab 130 electrically connected to the positive electrode collector 110; tape 140 is attached to the edges of the positive electrode tab 130 and the positive electrode coating 120 to prevent edge burrs from piercing the diaphragm and causing a short circuit in the fast charging cell.

[0063] Starting from the positive electrode tab 130, a positive electrode coating notch 121 is provided on the positive electrode coating 120 at the corner of the fast charging cell; positive electrode coating notches are provided at a total of n=3 layers, a total of 4 corners, and a total of 5 positive electrode coating notches are provided at each corner.

[0064] Each positive electrode coating notch is a solid line notch with a width of 80 μm and a depth of 15 μm; at each corner, the distance between two adjacent positive electrode coating notches is 1.5 mm; the positive electrode coating notch spans through the positive electrode coating.

[0065] The positive electrode is set up as follows: the positive electrode active material LiCoO2 (purchased from Xiamen Tungsten New Energy), the conductive agent acetylene black, the conductive agent carbon nanotubes, and the binder polyvinylidene fluoride (PVDF) are slurried in NMP at a weight ratio of 97.9:0.6:0.5:1.0 and then coated on the surfaces of both sides of the positive electrode current collector aluminum foil to form a single-sided positive electrode coating with a thickness of 35μm; then cold pressed and striped to obtain the appropriate size, and finally laser etching technology was used to set the gap in the positive electrode coating with reference to the above parameters.

[0066] refer to Figure 1(Below), the negative electrode used in this example includes a negative electrode current collector 210, a negative electrode coating 220 provided on the surface of the negative electrode current collector 210, and a central negative electrode tab 230 electrically connected to the negative electrode current collector 210; tape 140 is attached to the edges of the negative electrode tab 230 and the negative electrode coating 220 to prevent edge burrs from piercing the diaphragm and causing a short circuit in the fast charging cell.

[0067] Negative electrode coating notches 221 are provided in the negative electrode coating 220 around the projection of the positive electrode tab 130 onto the negative electrode. These notches 221 are evenly distributed across the entire surface of the negative electrode, with a total of m = 3 layers. These notches 221 are solid lines with a width of 100 μm and a depth of 15 μm. The spacing between adjacent notches is 1.5 mm, and the notches extend across the entire negative electrode coating.

[0068] The negative electrode is set up as follows: the negative electrode active material, dispersant, and binder are mixed in water in a weight ratio of 97.7:1:1.3 to prepare a slurry; the resulting slurry is applied to both sides of the negative electrode current collector copper foil to obtain a negative electrode coating with a single-sided thickness of 40μm, and then cold pressed and striped to obtain a negative electrode of appropriate size; finally, referring to the above parameters, a negative electrode coating notch is laser-etched on the surface of the negative electrode coating.

[0069] The negative electrode active coating used in this example is a mixture of graphite and silicon-carbon negative electrode materials in a mass ratio of 9:1, both of which were purchased from Zichen.

[0070] Diaphragm: The diaphragm used in this example was purchased from Zhuogao and consists of a PP diaphragm base and a coating provided on the surface of the PP diaphragm base; the coating is 2 μm thick and is a mixture of vinylidene fluoride and alumina ceramic particles in a mass ratio of 50%:50%.

[0071] It should be noted that Figure 1 The lengths of the positive and negative electrodes, the number and width of the positive and negative electrode coating gaps are schematic. The parameters measured in the figures do not represent the actual parameters of this example.

[0072] Examples 2 to 11 and Comparative Example 1 each provide a fast charging cell, which differs from Example 1 in that:

[0073] Some parameters are different, and the specific differences are shown in Table 1.

[0074] Table 1 Partial parameters of Examples 1 to 11 and Comparative Example 1

[0075] Case N n m Case N n m Example 1 20 3 3 Example 8 12 6 6 Example 2 20 6 3 Example 9 20 20 20 Example 3 20 10 3 Example 10 20 12 12 Example 4 20 6 6 Example 11 12 12 12 Example 5 20 6 8 Comparative Example 1 20 0 0 Example 6 20 6 10 Comparative Example 2 20 6 0 Example 7 12 3 6 Comparative Example 3 20 0 6

[0076] Application Examples

[0077] This example provides a lithium-ion battery, which is specifically composed of a battery shell, a battery cell and an electrolyte, wherein the battery shell contains the battery cell and the electrolyte; the electrolyte impregnates the battery cell; the battery cell is a fast charging cell provided in the embodiment or comparative example.

[0078] The electrolyte is prepared by mixing ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), and propyl propionate (PP) in a volume ratio of 1:1:4:4 to obtain a mixed organic solvent, and then dissolving fully dried lithium salt LiPF6 in the mixed organic solvent at a ratio of 1 mol / L to prepare the electrolyte.

[0079] Test Case

[0080] This example tests the charging window and cycle performance of the lithium-ion battery obtained in the application example,

[0081] Charge Window Test Protocol: After constant-rate charging at a specific rate (X) to 4.5V, cycle to 0.05C, then DC to 3.0V at 0.7C. After 20 cycles, disassemble the interface. If no lithium deposition occurs at the interface, the charge capability passes at charge rate X. The charge rate is then measured at X + 0.1C until the charge rate (charge capability) at which no lithium deposition occurs is obtained. Record the results in Table 2.

[0082] Cycling protocol: Constant-rate charging to 4.25V at the moderate rate obtained during the charge window test, followed by 1.8CCC to 4.5V, CV to 0.05C, and DC to 3.0V at 0.7C. The number of cycles until the capacity dropped below 80% was recorded. The test results are shown in Table 2.

[0083] Table 2 Performance of fast charging cells obtained in Examples and Comparative Examples

[0084] Case Charging capacity / C Number of cycles Example 1 2.8C 700 Example 2 2.8C 810 Example 3 2.8C 870 Example 4 3.0C 1000 Example 5 3.1C 950 Example 6 3.1C 910 Example 7 2.9C 1000 Example 8 3.1C 950 Example 9 3.0C 500 Example 10 3.0C 600 Example 11 3.1C 550 Comparative Example 1 2.4C 200 Comparative Example 2 2.6C 500 Comparative Example 3 2.8C 600

[0085] From the results of Comparing Examples 1 to 3, it can be seen that when the number of layers of the negative electrode coating gap remains unchanged, the charging capacity of the fast charging cell remains basically unchanged, but as the number of layers of the positive electrode coating gap increases, the cycle performance tends to increase; this is because the charging capacity mainly depends on the ability of the negative electrode to accept lithium ions, and the cycle performance depends on the ability of the positive and negative electrodes to consume electrolyte, as well as the electrolyte retention capacity and other factors, so increasing the number of layers of the positive electrode coating gap will improve the cycle performance.

[0086] Comparing Examples 2, 4, and 6, we can see that when the number of notches in the positive electrode coating remains unchanged and the number of notches in the negative electrode coating increases, the charging capacity of the fast-charging cell shows a trend of first increasing and then reaching equilibrium, while the cycling performance shows a trend of first increasing and then decreasing. This is because the current density of the negative electrode tends to reach equilibrium when it is farther away from the negative electrode tab. Further increasing the number of notches in the negative electrode coating does not significantly affect the negative electrode's ability to accept lithium ions. However, as the number of notches in the negative electrode coating increases, the side reactions between the silicon-carbon negative electrode material and the electrolyte in the negative electrode increase, thereby reducing the cycling performance.

[0087] By comparing Examples 7 to 8 and 11 with other examples, it can be seen that when the number of winding layers of the fast charging cell is small, the technical solution provided by the present invention is still applicable and can achieve good technical effects.

[0088] Comparing Examples 1, 4, and 8 to 11, it can be seen that when the ratio of the positive electrode coating gap to the negative electrode coating gap remains unchanged, with the increase of n / N, the charging capacity and cycle performance both show a trend of first increasing and then decreasing. The reason is that with the increase of n / N, the ability of the negative electrode to accept lithium ions and the storage capacity of the electrolyte both increase, and the side reactions also increase. The weights of the three factors are different, and the above results appear after the combined effect. In addition, when the ratio of the positive electrode coating gap to the negative electrode coating gap, as well as n / N, remains unchanged and the number of overall winding layers of the fast charging core is increased, its charging capacity and cycle performance decrease slightly. This is because the heat dissipation capacity of the large-capacity fast charging core decreases, which in turn increases the occurrence of side reactions.

[0089] Comparison of the Examples with Comparative Example 1 demonstrates that the fast-charging cell provided by this utility model, by rationally positioning the notches on the positive and negative electrodes, effectively improves charging capacity and cycle performance. Lithium-ion batteries incorporating these fast-charging cells exhibit excellent performance and are expected to be used in digital products and new energy vehicles.

[0090] By comparing Example 4 with Comparative Examples 1 to 3, it can be seen that the fast charging core provided by the present invention, if only the positive electrode coating notch is provided, or only the negative electrode coating notch is provided, can improve its fast charging and cycle performance in a small range, but the improvement effect is very limited.

[0091] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A fast charging cell, comprising a positive electrode, a separator, and a negative electrode wound together; the separator is disposed between the positive electrode and the negative electrode; the negative electrode comprises a negative electrode current collector, a negative electrode coating disposed on the surface of the negative electrode current collector, and a central negative electrode tab electrically connected to the negative electrode current collector; the positive electrode comprises a positive electrode current collector, a positive electrode coating disposed on the surface of the positive electrode current collector, and a central positive electrode tab electrically connected to the positive electrode current collector; characterized in that: Starting from the positive electrode tab, a positive electrode coating notch is provided on the positive electrode coating at a corner of the fast charging cell; A negative electrode coating notch is provided on the negative electrode coating around the projection position of the positive electrode tab on the negative electrode.

2. The fast charging cell according to claim 1, characterized in that: The total number of winding layers of the fast charging core is N, the number of winding layers with the positive electrode coating gap is n; and 1≤n≤N / 2; And / or, the total number of winding layers of the fast charging core is N, the number of winding layers with the negative electrode coating gap is m; and 3≤m≤N / 2.

3. The fast charging cell according to claim 1, characterized in that: The positive electrode coating gap and / or the negative electrode coating gap are continuous solid line gaps, or are dotted line gaps formed by connecting pore structures.

4. The fast charging cell according to claim 3, characterized in that: The width of the gap in the positive electrode coating is 20 to 80 μm; and / or the width of the gap in the negative electrode coating is 30 to 120 μm.

5. The fast charging cell according to claim 3, characterized in that: The depth of the notch in the positive electrode coating is 1 / 4 to 2 / 3 of the thickness of the positive electrode coating; and / or the depth of the notch in the negative electrode coating is 1 / 4 to 2 / 3 of the thickness of the negative electrode coating.

6. The fast charging cell according to claim 3, characterized in that: The spacing between the gaps in the negative electrode coating is 1 to 2 mm.

7. The fast charging cell according to claim 2, characterized in that: The total number N of winding layers of the fast charging core is in the range of 10 to 50; and / or, the raw material for preparing the negative electrode coating includes a silicon-based negative electrode material.

8. The fast charging cell according to any one of claims 1 to 7, characterized in that: The thickness of the positive electrode coating is 20 to 100 μm; and / or the thickness of the negative electrode coating is 40 to 120 μm.

9. A lithium-ion battery, characterized in that: The lithium-ion battery comprises the fast-charging cell according to any one of claims 1 to 7, and an electrolyte that soaks the fast-charging cell.

10. An electric product, characterized in that: The raw materials for preparing the electric product include the fast charging cell according to any one of claims 1 to 8, or the lithium-ion battery according to claim 9.

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