Full-tab cylindrical lithium ion battery and power utilization device

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a full-tab cylindrical lithium ion battery and a power utilization device, the full-tab cylindrical lithium ion battery comprises a winding type battery cell, and a positive plate, a diaphragm and a negative plate which are laminated according to a specific mode; the positive plate comprises a positive current collector as well as a positive slurry coating area and a positive empty foil area which are positioned on at least one surface of the positive current collector; the negative plate comprises a negative current collector as well as a negative slurry coating area and a negative empty foil area which are positioned on at least one surface of the negative current collector; after winding, the positive empty foil area and the negative empty foil area respectively form a positive tab and a negative tab through a kneading, cutting and stacking or ultrasonic process; when the battery discharges at 10C, the slope of a curve relation formed by data fitting of the temperature rise coefficient and the discharge current is 0.2-1, the temperature rise performance of the full-tab battery cell is obviously superior to that of a traditional tab battery, more electric quantity can be discharged in a lower temperature interval, and the full-tab battery cell has relatively good safety and relatively high energy density.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly relates to an all-tab cylindrical lithium-ion battery and an electrical device using the same. Background Art

[0002] The development of high-performance portable electric devices has greatly enriched people's daily life and work. However, with the continuous growth of demand, the existing battery technology has gradually become a bottleneck restricting the development of these devices. High-performance portable electric devices generally use lithium-ion batteries as the energy source. Lithium-ion batteries have advantages such as high energy density and long cycle life. However, with the continuous expansion of application scenarios, the existing lithium-ion battery technology has been difficult to meet the requirements.

[0003] Although the energy density of existing lithium-ion batteries has been improved compared with traditional batteries, it still cannot meet the demand. The low energy density results in insufficient battery life of the device, restricting the usage scenarios. There is also a problem that the charging speed of lithium-ion batteries is relatively slow, especially in low-temperature environments, the charging speed drops significantly, which causes users to spend a lot of time waiting for charging during use, reducing the usage experience of the device. In addition, the cycle life of lithium-ion batteries is relatively short, especially under harsh conditions such as high temperature and high-rate discharge, the battery life will be further shortened, which leads to frequent battery replacement during the use of the device, increasing the maintenance cost, and in abnormal situations such as overcharging, over-discharging, and short-circuiting, thermal runaway is likely to occur, resulting in safety accidents such as fire and explosion. Summary of the Invention

[0004] In order to improve the charge and discharge performance and temperature rise safety of existing lithium-ion batteries, an all-tab cylindrical lithium-ion battery and an electrical device using the same are provided. The present invention improves the structural parameters of the negative electrode sheet, so that the charge and discharge performance and temperature rise performance of the battery are significantly improved. When the obtained battery discharges at a current of 10C, the slope of the curve relationship formed by data fitting between the battery temperature rise coefficient and the discharge current is 0.2 to 1, and the battery has good temperature rise performance.

[0005] In order to achieve the above object, the present invention is realized through the following technical solutions:

[0006] An all-tab cylindrical lithium-ion battery, comprising a wound battery cell, and the wound battery cell is formed by winding a stacked positive electrode sheet, a separator, and a negative electrode sheet;

[0007] The positive electrode sheet includes a positive electrode current collector and a positive electrode paste coating area and a positive electrode bare foil area located on at least one surface of the positive electrode current collector; the negative electrode sheet includes a negative electrode current collector and a negative electrode paste coating area and a negative electrode bare foil area located on at least one surface of the negative electrode current collector;

[0008] During lamination, in the width direction of the electrode sheet: control the width of the negative electrode paste coating area exceeding the end of the positive electrode paste coating area to be 1 - 5 mm; control the width of the separator exceeding the end of the positive electrode paste coating area to be 1 - 4 mm; in the length direction of the electrode sheet: control the width of the positive electrode bare foil area exceeding the separator to be 1 - 6 mm; control the width of the negative electrode bare foil area exceeding the end of the separator to be 1 - 6 mm;

[0009] After winding, the positive electrode bare foil area and the negative electrode bare foil area are respectively formed into positive electrode tabs and negative electrode tabs through processes such as flattening, cutting and laminating, or ultrasonic processing;

[0010] When the battery is discharged at 10C, the slope of the curve relationship formed by data fitting of its temperature rise coefficient and discharge current is 0.2 to 1. During testing, for example, after a lithium-ion battery is fully charged at 0.2C, it is discharged at 5C, 10C, 15C, 20C, and 25C respectively for discharge testing, and then a curve graph of the temperature rise coefficient and discharge current can be plotted; for example, when discharged at 10C, the slope of the curve relationship formed by the temperature rise coefficient of the battery and the discharge current is more than 49% lower than the slope of the curve relationship formed by the temperature rise coefficient of the traditional tab cylindrical battery and the discharge current, proving that the heat dissipation performance of the full-tab battery of the present invention is much higher than that of the traditional tab battery, and the increase rate of the temperature rise coefficient of the full-tab battery of the present invention is much lower than that of the traditional tab battery, so that the full-tab battery can discharge more electricity in the same temperature range. The method for obtaining the above parameters: the parameters of the electrode sheet coating area and the bare foil area are obtained by disassembling the battery and performing a metallographic experiment or a CT test on the longitudinal section of the full-tab cylindrical battery.

[0011] Preferably, when the discharge capacity C0 measured at a discharge rate of 0.2C of the battery is 4 ± 0.2 Ah, the slope of the curve relationship formed by data fitting of its temperature rise coefficient and discharge current when the battery is discharged at 10C is between 0.2 and 0.5;

[0012] When the discharge capacity C0 measured at a discharge rate of 0.2C of the battery is 5 ± 0.2 Ah, the slope of the curve relationship formed by data fitting of its temperature rise coefficient and discharge current when the battery is discharged at 10C is 0.5 to 1;

[0013] The specific method for testing the discharge capacity of the battery at 0.2C is as follows:

[0014] (1) At room temperature, the battery is charged at a constant current to 4.2V at a charging rate of 1C and then charged at a constant voltage until the current is 0.025C, and left standing for more than 15 minutes;

[0015] (2) At room temperature, the battery is discharged at a constant current to 2.5V at a discharge rate of 0.2C, and the discharge capacity is recorded as C0 ampere-hour.

[0016] Further, during the battery discharge process, the following relationship is satisfied: lg M = D * lg i - T;

[0017] where the value of D ranges from 1.9 to 2.2; the value of T ranges from 1.8 to 2.6;

[0018] where i is the discharge current of the battery during the discharge process, with the unit A (ampere), and the discharge current is 1C to 20C in terms of the discharge rate (assuming the battery capacity is 4Ah, then the 1C current is 4A, 10C is 40A, and 20C is 80A);

[0019] where M is the temperature rise coefficient of the battery during the discharge process, with the unit K / min (Kelvin / minute).

[0020] Furthermore, the current coefficient J satisfies the following relationship: 0.003 ≤ J ≤ 0.006;

[0021] The method for obtaining the current coefficient J is as follows: taking the square of the discharge current i (i.e., i 2 ) as the abscissa, where i takes 5C, 10C, 15C, 20C, and 25C respectively, and taking the temperature rise coefficient M as the ordinate. After plotting and data fitting, the slope of the straight line of the obtained linear equation is the current coefficient J. The current coefficient J affects the balance between the heat dissipation effect and the heat generation effect of the battery. If the value of J is too large, the battery temperature rises faster, and the internal energy release of the battery is restricted. If the value of J is too small, the internal temperature of the battery cannot be released normally, and dangerous situations such as thermal runaway are likely to occur.

[0022] Further, during lamination, in the width direction of the electrode sheet: control the width of the negative electrode paste coating area exceeding the end of the positive electrode paste coating area to be 2 - 4 mm; control the width of the separator exceeding the end of the positive electrode paste coating area to be 1.1 - 3.5 mm;

[0023] During lamination, in the length direction of the electrode sheet: control the width of the positive electrode bare foil area exceeding the separator to be 3 - 5 mm; control the width of the negative electrode bare foil area exceeding the end of the separator to be 2 - 4.5 mm.

[0024] Further, the percentage of the area of the positive electrode bare foil area in the total area of the positive electrode sheet ranges from 3% to 10%; the percentage of the area of the negative electrode bare foil area in the total area of the negative electrode sheet ranges from 2% to 15%.

[0025] Further, the positive electrode paste includes a positive electrode active material, a binder, and a positive electrode conductive agent;

[0026] Among them, the positive electrode active material is one or more of lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminate, and the nickel atomic ratio exceeds 0.8 in the positive electrode active material. Using ternary high-nickel materials for the positive electrode can increase the specific energy of the lithium-ion cylindrical battery to be greater than or equal to 274.5 Wh / kg;

[0027] The positive electrode conductive agent is selected from at least two of conductive carbon black, acetylene black, carbon nanotubes, graphite, and graphene. By using a combination of multiple conductive agents, an internal conductive network of the electrode sheet is constructed, the internal resistance of the battery is reduced, and the conductive performance of the battery is improved.

[0028] Furthermore, the negative electrode slurry includes a negative electrode active material, a binder, and a negative electrode conductive agent;

[0029] Among them, the negative electrode active material is selected from at least two of natural graphite, artificial graphite, hard carbon, soft carbon, mesophase carbon microspheres, silicon oxide materials, and silicon-carbon materials;

[0030] The negative electrode conductive agent is selected from at least two of conductive carbon black, acetylene black, carbon nanotubes, graphite, and graphene. Using graphite doped with high-silicon materials for the negative electrode can increase the specific energy of the lithium-ion cylindrical battery; and by using a combination of multiple conductive agents, an internal conductive network of the electrode sheet is constructed, the internal resistance of the battery is reduced, and the conductive performance of the battery is improved.

[0031] Furthermore, the single-sided surface density of the negative electrode sheet is 0.006 - 0.012 g / cm 2 .

[0032] Furthermore, the average thickness of the coating in the coating area of the negative electrode slurry on the surface of the negative electrode current collector is 40 - 80 μm.

[0033] Furthermore, the negative electrode current collector in the negative electrode sheet is copper foil, and the average thickness of the copper foil is 5 - 10 μm.

[0034] Furthermore, the battery further includes an electrolyte;

[0035] The electrolyte includes an electrolyte salt LiPF6 and additives;

[0036] The concentration of the electrolyte salt in the electrolyte is in the range of 1.05 mol / kg - 1.35 mol / kg;

[0037] The additives are selected from fluorine compounds, and the fluorine compounds include at least one of fluorinated carboxylic acid esters, fluorinated ethers, fluoroethylene carbonate, trifluorocarbonate, and trifluoroethyl methyl carbonate.

[0038] On the other hand, the present invention provides an electrical device, including a full-tab cylindrical lithium-ion battery as described in any one of the above.

[0039] Beneficial technical effects:

[0040] The cylindrical lithium-ion battery of the present invention adopts a specific lamination method to form a full-tab structure design, and jointly improves the charge and discharge performance, temperature rise performance of the lithium-ion battery and increases the energy density of the battery by combining aspects such as the resistivity of the negative electrode sheet, the thickness of the negative electrode active material coating, the thickness of the negative electrode current collector copper foil, and the areal density of the negative electrode sheet; when the battery of the present invention discharges at a current of 10C, the temperature rise coefficient M is reduced by more than 58% compared with the traditional tab battery, and when discharging at a current of 10C, the slope of the curve relationship formed by the data fitting of the battery temperature rise coefficient and the discharge current is 0.2 to 1, which is reduced by more than 49% compared with the traditional tab battery, greatly improving the battery temperature rise performance, and the energy density is greater than or equal to 274.5 Wh / kg. The temperature rise performance of the full-tab battery cell of the present invention is significantly better than that of the traditional tab battery, and more electricity can be discharged in a lower temperature range; the lithium-ion battery of the present invention not only improves the safety and energy density, but also better meets the usage needs of consumers. Description of the Drawings

[0041] Figure 1 It is a schematic structural diagram of the unwound wound battery cell of the battery of the present invention;

[0042] Figure 2 It is a schematic structural diagram of the wound wound battery cell of the battery of the present invention after winding;

[0043] Figure 3 Curves of lg temperature rise coefficient and lg discharge current of the batteries of Examples 1-2 and Comparative Example 1; among them, the square marks are the data points of Comparative Example 1, the triangular marks are the data points of Example 1, and the circular marks are the data points of Example 2;

[0044] Figure 4 It is a curve diagram of the discharge current and temperature rise coefficient of the battery of Example 1;

[0045] Figure 5 It is a curve diagram of the discharge current and temperature rise coefficient of the battery of Comparative Example 1;

[0046] Figure 6 It is a curve diagram of the temperature rise coefficient changing with the discharge current of the batteries of Examples 1-2 and Comparative Example 1. Detailed Embodiments

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments and drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and in no way restrictive of the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0048] Unless otherwise specifically stated, the numerical values set forth in these embodiments do not limit the scope of the present invention. Techniques and methods known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques and methods should be regarded as part of the specification. In all examples shown and discussed herein, any specific values should be construed as merely exemplary and not as limiting. Thus, other examples of the exemplary embodiments may have different values.

[0049] For the experimental methods without specific conditions in the following examples, they are generally determined according to national standards; if there is no corresponding national standard, they are carried out according to general standard requirements or general methods.

[0050] The specific method for testing the discharge capacity of the battery at 0.2C is as follows:

[0051] (1) At room temperature, the battery is charged at a constant current at a charging rate of 1C until 4.2V, and then charged at a constant voltage until the current is 0.025C, and left standing for more than 15 minutes;

[0052] (2) At room temperature, the battery is discharged at a constant current at a discharge rate of 0.2C until 2.5V, and the discharge capacity is recorded as C0 Ah. At this time, the obtained C0 is the rated capacity.

[0053] If the discharge capacity of the battery is 4Ah, the discharge current at a discharge rate of 1C is 4A, the discharge current at a discharge rate of 10C is 40A, and the discharge current at a discharge rate of 20C is 80A.

[0054] The test method for the temperature rise coefficient M: At a normal temperature of 25°C, the battery cell is charged at 1C until the full charge SOC = 100%, and then charged at a constant current and constant voltage until the current is less than 0.05C, and left standing for 10 minutes. Then, at a discharge rate of 10C, the battery cell is discharged until the full discharge SOC = 0%. During the discharge process, when the temperature of the battery cell reaches 80°C, the discharge is directly cut off. Assuming the total discharge time is t min, then the difference between the temperature of the battery at the discharge cut-off and the temperature of the battery at normal temperature is 55°C (328.15K), then M = 328.15 / t, with the unit K / min (Kelvin / minute).

[0055] For the diaphragms in the following cases, PE diaphragms are selected, with a thickness of 10μm, ceramic coating thicknesses of 1mm on both sides, transverse tensile strength of 130 - 160MPa, longitudinal tensile strength of 140 - 170MPa, puncture strength of 300 - 600gf, and porosity of 40% - 50%.

[0056] Example 1

[0057] This case is a full-tab cylindrical 21700 lithium-ion battery with a 0.2C discharge capacity C0 = 4 Ah, including a wound-type battery cell as shown in Figure 2 the structure. The wound-type battery cell includes a stacked positive electrode sheet, a separator, and a negative electrode sheet wound together (with the positive electrode sheet wound inside).

[0058] The positive electrode sheet includes a positive current collector aluminum foil and positive electrode paste coating areas and positive electrode bare foil areas on two surfaces of the positive current collector; the width of the positive electrode sheet is 60 mm and the length is 1315 mm, and the area of the positive electrode bare foil area accounts for 10.6% of the total area of the positive electrode sheet.

[0059] The negative electrode sheet includes a negative current collector and negative electrode paste coating areas and negative electrode bare foil areas on two surfaces of the negative current collector; the width of the negative electrode sheet is 62 mm and the length is 1363 mm, and the area of the negative electrode bare foil area accounts for 7.2% of the total area of the negative electrode sheet.

[0060] The stacking state is as shown in Figure 1 When stacking, in the width direction of the electrode sheet: control the width of the negative electrode paste coating area exceeding the end of the positive electrode paste coating area to be 2 mm; control the width of the separator exceeding the end of the positive electrode paste coating area to be 2.6 mm.

[0061] When stacking, in the length direction of the electrode sheet: control the width of the positive electrode bare foil area exceeding the separator to be 5 mm; control the width of the negative electrode bare foil area exceeding the end of the separator to be 4 mm.

[0062] After winding, the positive electrode bare foil area is folded and compressed inward to form a positive electrode tab area, and the negative electrode bare foil area is folded and compressed inward to form a negative electrode tab area; the diameter of the wound-type battery cell is 21 mm.

[0063] Control the average axial overlapping height h1 of the formed positive electrode tab area to be 0.4 mm; control the average axial overlapping height h2 of the formed negative electrode tab area to be 0.3 mm; the higher the average thickness of the axial overlap of the tabs, the more it occupies the internal space of the battery case, which can reduce the battery energy density; the larger the diameter of the wound core, the more turns of the electrode sheet are wound, and the more layers of the tabs overlap. Too many or too few layers of the tabs overlapping will lead to greater difficulty in welding the current collector plate to the tabs, such as false welding, poor welding, overheating during welding, damage to the electrode sheet and separator, etc.

[0064] Among them, the negative electrode paste for forming the negative electrode paste coating area includes: 91 wt% artificial graphite, 5 wt% silicon, 1 wt% conductive agent acetylene black, 3 wt% negative electrode binder polyacrylic acid; using this negative electrode paste to coat on two surfaces of a negative current collector copper foil with a thickness of 8 μm, the average thickness of the coating after rolling and drying is 45 μm, and the single-sided areal density is 7.7 mg / cm 2, the resistivity of the formed negative electrode sheet is 7.61 Ω·cm;

[0065] Among them, the positive electrode paste for forming the positive electrode paste coating area includes: 95 wt% of LiNi 0.8 Co 0.1 Mn 0.1 O2, 1.1 wt% of carbon nanotube conductive agent, 2.4% of Super-P (conductive carbon black) conductive agent, and 1.5% of polyvinylidene fluoride PVDF binder; using this positive electrode paste to coat both surfaces of an aluminum foil with a positive electrode current collector thickness of 12 μm, the average thickness of the coating after rolling and drying is 40 μm, and the areal density per side is 12 mg / cm 2 , the resistivity of the formed positive electrode sheet is 1067.5 Ω·cm;

[0066] Then the above-mentioned wound type battery cell is placed in a housing, filled with an electrolyte (the formula is ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent, and then the fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1 mol / L, and 0.2% of the functional reagent vinylene carbonate and 0.2% of the functional reagent fluoroethylene carbonate are added) to impregnate the wound type battery cell, and sealed to form a battery.

[0067] For the battery in this case, the temperature rise coefficient M is tested with the discharge current i. A curve is plotted with lgi as the abscissa and lg M corresponding to the discharge current as the ordinate. The results are shown in Figure 3 each data marked by a triangle. The fitted linear relationship is lg M = 2.0329lg i - 2.4042 (in the linear relationship formula lg M = D*lg i - T, D = 2.0329, T = 2.4042). It is fitted into a quadratic equation curve. The curve relationship between the temperature rise coefficient M and the discharge current i is as shown in Figure 4 shown (corresponding to the data marked by blue triangles in Figure 6 ), Figure 4 the curve relationship formula in 2 is: y1 = 0.0061x

[0068] - 0.0835x + 0.4278 (Formula 1). When discharging at 10C, that is, discharging at a current of 40 Ah, taking x = 40 (A), the derivative of Formula 1 is y1’ = 0.0122x - 0.0835. Then substituting x = 40 into the derivative function y1’, the slope at this discharge current point value can be obtained as y1’ = 0.4045.

[0069] The current coefficient J of the battery in this case was tested: with the square of the discharge current i (i.e., i 2 ) as the abscissa, where i was taken as 5C, 10C, 15C, 20C, and 25C respectively, and the corresponding temperature rise coefficient M as the ordinate. The linear equation obtained after data fitting by plotting was y = 0.0042x, and the current coefficient J was 0.0042.

[0070] Comparative Example 1

[0071] This case was a traditional tabular cylindrical lithium-ion battery with a 0.2C discharge capacity C0 = 4Ah. One positive tab was welded at the middle position in the length direction of the positive electrode sheet, and one negative tab was welded at each of the two ends in the length direction of the negative electrode sheet. The remaining structures were the same as those in Example 1.

[0072] The temperature rise coefficient M of the battery in this case was tested with the discharge current i. A curve was plotted with lgi as the abscissa and lgM corresponding to the discharge current as the ordinate. The results are shown in Figure 3 by the square markers for each data. The fitted linear relationship was lgM = 2.0217lgi - 2.0079 (in the linear relationship formula lgM = D*lgi - T, D = 2.0217, T = 2.0079). The data was fitted into a quadratic equation curve. The curve relationship between the temperature rise coefficient M and the discharge current i was as shown in Figure 5 (corresponding to the data marked by the red triangles in Figure 6 ). Figure 5 The curve relationship formula in 2 was: y2 = 0.0093x

[0073] + 0.0619x - 0.5833 (Formula 2). When discharging at 10C, i.e., a current of 40Ah, taking x = 40 (A), the derivative of Formula 1 was y2’ = 0.0186x + 0.0619. Substituting x = 40 into the derivative function y2’, the slope at this discharge current point value could be obtained as y2’ = 0.8059.

[0074] The current coefficient J of the battery in this case was tested. The test method was the same as that in Example 1, and the current coefficient J of this case was tested to be J = 0.0093.

[0075] Comparing Example 1 with the comparative example, it can be seen that y1’ = 0.4045 of the battery in Example 1 was reduced by 49.8% compared with y2’ = 0.8059 of Comparative Example 1, and the battery energy density of Example 1 was increased by 14.5% compared with that of Comparative Example 1. This shows that when discharging at a large current of 10C, the temperature rise performance of the full-tab battery of the present invention is significantly better than that of the traditional tab battery, and more electricity can be discharged in a lower temperature range.

[0076] Example 2

[0077] This case is a full-tab cylindrical 21700 lithium-ion battery with a 0.2C discharge capacity C0 = 5Ah. Its structure is the same as that of the battery in Example 1, except that:

[0078] The width of the positive electrode sheet is 60 mm and the length is 1315 mm. The area of the positive electrode empty foil area accounts for 10.5% of the total area of the positive electrode sheet;

[0079] The width of the negative electrode sheet is 62 mm and the length is 1363 mm. The area of the negative electrode empty foil area accounts for 7.1% of the total area of the negative electrode sheet;

[0080] During lamination, in the width direction of the electrode sheet: control the width of the negative electrode slurry coating area exceeding the end of the positive electrode slurry coating area to be 2.5 mm; control the width of the separator exceeding the end of the positive electrode slurry coating area to be 3 mm;

[0081] During lamination, in the length direction of the electrode sheet: control the width of the positive electrode empty foil area exceeding the separator to be 4 mm; control the width of the negative electrode empty foil area exceeding the end of the separator to be 4.5 mm;

[0082] Control the average axial overlap height h1 of the positive electrode tab area after forming to be 0.3 mm;

[0083] Control the average axial overlap height h2 of the negative electrode tab area after forming to be 0.2 mm;

[0084] Among them, the negative electrode slurry for forming the negative electrode slurry coating area includes: 90 wt% of high-capacity artificial graphite, 6 wt% of silicon, 1 wt% of conductive agent acetylene black, and 3 wt% of negative electrode binder polyacrylic acid; use this negative electrode slurry to coat both surfaces of a copper foil with a negative electrode current collector thickness of 8 μm, and the average thickness of the coating after roll pressing and drying is 47 μm, and the single-sided areal density is 7.9 mg / cm 2 , and the resistivity of the formed negative electrode sheet is 7.92 Ω·cm;

[0085] Among them, the positive electrode slurry for forming the positive electrode slurry coating area includes: 95% of LiNi 0.9 Co 0.05 Mn 0.05 O2, 1.2 wt% of carbon nanotube conductive agent, 2.3 wt% of Super-P (conductive carbon black) conductive agent, and 1.5 wt% of polyvinylidene fluoride PVDF binder; use this positive electrode slurry to coat both surfaces of an aluminum foil (thickness 8 microns) of the positive electrode current collector, and the average thickness of the coating after roll pressing and drying is 46 μm, and the single-sided areal density is 16 mg / cm 2 , and the resistivity of the formed positive electrode sheet is 963.4 Ω·cm.

[0086] For the battery in this case, the temperature rise coefficient M was tested with respect to the discharge current i. A curve was plotted with lg i as the abscissa and lg M corresponding to the discharge current as the ordinate. The results are shown in Figure 3 the circular markers for each data in it. The fitted linear relationship is lg M = 2.038lg i - 2.3902 (in the linear relationship formula lgM = D*lg i - T, D = 2.038, T = 2.3902). Data fitting was performed on it to obtain a quadratic equation curve. The curve relationship between the temperature rise coefficient M and the discharge current i is: y3 = 0.0109x 2 - 0.2463x (Formula 3). When discharging at 10C, that is, discharging at a current of 50Ah, taking x = 50 (A), the derivative of Formula 3 is y3’ = 0.0218x - 0.2463. Substituting x = 50 into the derivative function y3’, the slope at this discharge current point value can be obtained as y3’ = 0.8437.

[0087] The energy density of the battery in this case was tested in accordance with GB / T 31484 to be 286.9 Wh / Kg.

[0088] The current coefficient J of the battery in this case was tested. The testing method is the same as that in Example 1, and the tested current coefficient J = 0.0056.

[0089] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered by the protection scope of the present invention.

Claims

1. A full-tab cylindrical lithium-ion battery, characterized in that It includes a wound cell, and the wound cell is formed by winding stacked positive electrode sheets, separators, and negative electrode sheets. The positive electrode sheet includes a positive electrode current collector and a positive electrode paste coating area and a positive electrode bare foil area located on at least one surface of the positive electrode current collector; the negative electrode sheet includes a negative electrode current collector and a negative electrode paste coating area and a negative electrode bare foil area located on at least one surface of the negative electrode current collector. During lamination, in the width direction of the electrode sheet: control the width of the negative electrode paste coating area exceeding the end of the positive electrode paste coating area to be 1 - 5 mm; control the width of the separator exceeding the end of the positive electrode paste coating area to be 1 - 4 mm; in the length direction of the electrode sheet: control the width of the positive electrode bare foil area exceeding the separator to be 1 - 6 mm; control the width of the negative electrode bare foil area exceeding the end of the separator to be 1 - 6 mm. After winding, the positive electrode bare foil area and the negative electrode bare foil area are respectively formed into positive electrode tabs and negative electrode tabs through processes such as flattening, cutting and overlapping, or ultrasonic treatment. When the battery discharges at 10C, the slope of the curve relationship formed by data fitting of its temperature rise coefficient and discharge current is 0.2 to 1.

2. The all-tab cylindrical lithium-ion battery according to claim 1, wherein When the discharge capacity C0 measured at a discharge rate of 0.2C of the battery is 4 ± 0.2 Ah, the slope of the curve relationship formed by data fitting of its temperature rise coefficient and discharge current when the battery discharges at 10C is between 0.2 and 0.

5. When the discharge capacity C0 measured at a discharge rate of 0.2C of the battery is 5 ± 0.2 Ah, the slope of the curve relationship formed by data fitting of its temperature rise coefficient and discharge current when the battery discharges at 10C is 0.5 to 1.

3. The all-pole-tab cylindrical lithium-ion battery according to claim 1, characterized in that, During the discharge process of the battery, the following relationship is satisfied: lg M = D * lg i - T; Where the value of D ranges from 1.9 to 2.2; the value of T ranges from 1.8 to 2.6; Where i is the discharge current during the discharge process of the battery, with the unit A, and the discharge current is 1C - 20C in terms of discharge rate; Where M is the temperature rise coefficient during the discharge process of the battery, with the unit of Kelvin per minute.

4. The all-pole-tab cylindrical lithium-ion battery according to claim 3, wherein, The current coefficient J satisfies the following relationship: 0.003 ≤ J ≤ 0.006; The method for obtaining the current coefficient J is: taking the square of the discharge current i as the abscissa, where i takes 5C, 10C, 15C, 20C, 25C respectively, and taking the temperature rise coefficient M as the ordinate, and the slope of the straight line of the linear equation obtained after data fitting of the plotted graph is the current coefficient J.

5. The all-pole-tab cylindrical lithium-ion battery according to claim 1, wherein, During lamination, in the width direction of the electrode sheet: control the width of the negative electrode paste coating area exceeding the end of the positive electrode paste coating area to be 2 - 4 mm; control the width of the separator exceeding the end of the positive electrode paste coating area to be 1.1 - 3.5 mm. During lamination, in the length direction of the electrode sheet: control the width of the positive electrode bare foil area exceeding the separator to be 3 - 5 mm; control the width of the negative electrode bare foil area exceeding the end of the separator to be 2 - 4.5 mm.

6. The all-pole-tab cylindrical lithium-ion battery according to claim 1, wherein The percentage of the area of the positive electrode empty foil region in the total area of the positive electrode sheet ranges from 3% to 10%; the percentage of the area of the negative electrode empty foil region in the total area of the negative electrode sheet ranges from 2% to 15%.

7. The all-pole-ear cylindrical lithium-ion battery according to claim 1, wherein The positive electrode slurry includes a positive electrode active material, a binder, and a positive electrode conductive agent; wherein the positive electrode active material is one or more of lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminate, and the nickel atomic ratio exceeds 0.8 in the positive electrode active material; The positive electrode conductive agent is selected from at least two of conductive carbon black, acetylene black, carbon nanotubes, graphite, and graphene.

8. A full-tab cylindrical lithium-ion battery according to claim 1, wherein, The negative electrode slurry includes a negative electrode active material, a binder, and a negative electrode conductive agent; wherein the negative electrode active material is selected from at least two of natural graphite, artificial graphite, hard carbon, soft carbon, mesocarbon microbeads, silicon oxide materials, and silicon carbon materials; The negative electrode conductive agent is selected from at least two of conductive carbon black, acetylene black, carbon nanotubes, graphite, and graphene.

9. The all-pole-tab cylindrical lithium-ion battery according to claim 1, wherein The single-sided areal density of the negative electrode sheet is 0.006 to 0.012 g / cm 2 ; the resistivity of the negative electrode sheet is 3.5 to 18.9 Ω·cm.

10. A full-tab cylindrical lithium-ion battery according to claim 1, wherein The average thickness of the coating in the negative electrode slurry coating region on the surface of the negative electrode current collector is 40 - 80 μm.

11. A full-tab cylindrical lithium-ion battery according to claim 1, wherein, In the negative electrode sheet, the negative electrode current collector is a copper foil, and the average thickness of the copper foil is 5 - 10 μm.

12. The all-pole-ear cylindrical lithium-ion battery according to claim 1, characterized in that, The battery further includes an electrolyte; The electrolyte includes an electrolyte salt LiPF6 and an additive; The concentration of the electrolyte salt in the electrolyte ranges from 1.05 mol / kg to 1.35 mol / kg; The additive is selected from fluorine compounds, and the fluorine compounds include at least one of fluorinated carboxylic acid esters, fluorinated ethers, fluoroethylene carbonate, trifluorocarbonate, and trifluoroethyl methyl carbonate.

13. An electrical device, comprising a full-tab cylindrical lithium-ion battery according to any one of claims 1 - 12.

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