Lithium ion full-tab cylindrical secondary battery and electric equipment

Abstract

The invention relates to the technical field of lithium ion batteries, in particular to a lithium ion full-tab cylindrical secondary battery and electric equipment. The battery cell is formed by winding a positive plate, a diaphragm and a negative plate; the two wide edges of the negative plate are named as a negative winding starting end and a negative winding ending end respectively, a certain length is cut off from the edges of the two long edges of the negative empty foil area, and the two wide edges of the remaining length of the negative empty foil area are named as a first starting end and a first ending end respectively; the length between the first starting end and the cathode winding starting end is a1, the distance between the first ending end and the cathode winding ending end is b1, the height of the cathode empty foil area is h0, and the following relations are satisfied: 17 < = a1 / h0 < = 55 and 5 < = b1 / h0 < = 25. Under the same discharge current, compared with a traditional battery, the temperature rise coefficient of the battery is relatively low, the problem of too fast temperature rise in the battery using process can be effectively controlled, the safety of the lithium ion battery is improved, and the cycle life of the lithium ion battery is prolonged.

Description

Technical Field

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

[0002] With the rapid development of technology, portable power tools have become an indispensable partner in people's lives and work. These tools are widely welcomed for their convenience and high efficiency. However, while enjoying the convenience brought by power tools, some technical challenges are also faced, especially problems related to batteries.

[0003] Firstly, excessive temperature rise is a common problem in power tool batteries. During use, the internal resistance of the battery causes energy loss, which is converted into heat, increasing the battery temperature. Excessive temperature rise not only affects the battery performance and shortens the service life but may also lead to safety accidents. Secondly, the effective discharge capacity is relatively low, meaning that the actual usable capacity of the battery is lower than the theoretical capacity, resulting in insufficient battery life for power tools and affecting work efficiency. Moreover, poor safety performance is another major problem in battery technology. Due to the complex chemical reactions inside the battery, if not properly managed, it may lead to battery short circuit, leakage, or even explosion. In recent years, power tool battery safety accidents have occurred frequently, posing safety hazards to users. Finally, the problem of insufficient battery life makes power tools need to be charged frequently during use, reducing the user experience.

[0004] Digging deeper into the root causes of these problems, it can be found that the structure of existing batteries is difficult to meet the requirements of the new generation of power tools. On the one hand, the energy density of existing batteries is relatively low and cannot meet the requirements of high-performance power tools for battery life. On the other hand, the safety performance and stability of the batteries still need to be improved. Summary of the Invention

[0005] To solve the above technical problems, a lithium-ion all-terminal cylindrical secondary battery and an electrical device using the same are provided. The present invention obtains an improved battery cell by changing the terminal design, electrode design, and winding design, so that the internal resistance of the obtained battery is reduced by 70% compared with the batteries in the prior art, the working temperature rise drops by 30%, the total effective energy throughput of the battery is increased by 80%, and it can also support a charging rate of at least 3C.

[0006] To achieve the above object, the present invention is realized through the following technical solutions:

[0007] A lithium-ion all-terminal cylindrical secondary battery includes a battery cell and a housing;

[0008] The battery cell is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet;

[0009] The positive electrode sheet includes a positive electrode current collector, and a positive electrode paste coating area located on at least one of its surfaces and a positive electrode bare foil area without a coating; the negative electrode sheet includes a negative electrode current collector, and a negative electrode paste coating area located on at least one of its surfaces and a negative electrode bare foil area without a coating;

[0010] The negative electrode paste coating area is formed by coating a negative electrode paste on at least one surface of the negative electrode current collector, and the negative electrode paste includes graphite and silicon-oxygen material;

[0011] Name the two wide sides of the negative electrode sheet as the negative electrode winding start end and the negative electrode winding end respectively, and the lengths of the edges of the two long sides of the negative electrode bare foil area cut off are the first distance and the second distance respectively;

[0012] The length between the first distance and the negative electrode winding start end is a1, the distance between the second distance and the negative electrode winding end is b1, and let the height of the negative electrode bare foil area be h0, then the following relationship is satisfied: 17 ≤ a1 / h0 ≤ 55, 5 ≤ b1 / h0 ≤ 25, and the units of a1, b1, and h0 are all mm.

[0013] Furthermore, h0 is 0.18% - 0.45% of the total length of the negative electrode sheet; a1 accounts for 6.25% - 12% of the total length of the negative electrode sheet, and b1 accounts for 1.8% - 5.2% of the total length of the negative electrode sheet.

[0014] Furthermore, h0 = 3 - 6mm, a1 = 100 - 160mm, b1 = 30 - 70mm. Preferably, 20 < a1 / h0 < 30, 8 < b1 / h0 < 15.

[0015] Furthermore, name the two wide sides of the positive electrode sheet as the positive electrode winding start end and the positive electrode winding end respectively, and the lengths of the edges of the two long sides of the positive electrode bare foil area cut off are the third distance and the fourth distance respectively;

[0016] The length between the third distance and the positive electrode winding start end is a2, the distance between the fourth distance and the positive electrode winding end is b2, and let the height of the positive electrode bare foil area be h1, then h1 is 0.19% - 0.69% of the total length of the positive electrode sheet, a2 accounts for 6.7% - 12.7% of the total length of the positive electrode sheet, and b2 accounts for 1.6% - 6.15% of the total length of the positive electrode sheet.

[0017] Furthermore, h1 = 3 - 9mm, a2 = 105 - 165mm, b2 = 26 - 80mm.

[0018] Furthermore, the battery also satisfies at least one of the following conditions:

[0019] (1) The total length of the positive electrode sheet is 1300 - 1550mm;

[0020] (2) The total length of the negative electrode sheet is 1330 - 1600 mm;

[0021] (3) The separator includes a first separator and a second separator located on both sides of the negative electrode sheet. The length of the first separator is 1370 - 1675 mm, and the length of the second separator is 1400 - 1710 mm;

[0022] (4) The coating area of the positive electrode paste coating area is 770 - 930 cm 2 ;

[0023] (5) The coating area of the negative electrode paste coating area is 880 - 1023 cm 2 ;

[0024] (5) The areal capacity of the positive electrode sheet is 2 - 2.7 mAh / cm 2 ;

[0025] (6) The areal capacity of the negative electrode sheet is 2.1 - 2.85 mAh / cm 2 ;

[0026] (7) At least one edge of the positive electrode paste coating area has an insulating coating area coated with inorganic ceramics. The inorganic ceramics are selected from any one or a combination of aluminum oxide, manganese dioxide, magnesium oxide, silicon dioxide, titanium dioxide, zirconium dioxide, zinc oxide, iron(III) oxide, boehmite, calcite;

[0027] And the average particle size D50 of the inorganic ceramics is 0.5 - 3 μm. The width direction of the insulating coating area is arranged along the width direction of the positive electrode sheet, and the width of the insulating coating area accounts for 1 - 3% of the width of the entire positive electrode sheet.

[0028] Further, the temperature rise coefficient m of the battery during the discharge process and the discharge current i satisfy the following linear relationship:

[0029] M = A1 * Z + B1;

[0030] Where Z = lg i, where i is the current during the discharge process of the battery, with the unit of ampere. The value of A1 ranges from 1.8 to 2.2; the value of B1 ranges from -1.8 to -2.5; the discharge rate is 2C - 25C (assuming the battery capacity is 4 Ah, then 1C current is 4A, 10C is 40A, and 20C is 80A);

[0031] Where M = lg m, where m is the temperature rise coefficient of the battery during the discharge process, with the unit of Kelvin per minute.

[0032] Furthermore, the mass percentage of the silicon-oxygen material in the negative electrode paste is a%, and a% = 1% - 30%.

[0033] Furthermore, the following relationship is satisfied between a% and the ratio A1 / B1: 2 ≤ |a * A1 / B1| ≤ 45. Through a large number of experiments, it is concluded that when the lithium-ion full-tab cylindrical secondary battery of the present invention satisfies 2 ≤ |a * A1 / B1| ≤ 45, the battery has an ultra-high discharge rate, good low-temperature charge and discharge performance, and an extremely long cycle life: 8A charging / 40A discharging cycle 1000 times at 25°C with 100% SOC, and the capacity retention rate is 80%; 15A / 40A full charge and full discharge 600 cycles at 25°C with 100% SOC, and the capacity retention rate is 90%; the life is extended compared with competing products, and the full life cycle cost is reduced; the battery with the structure of the present invention can achieve 70A continuous discharge and 250A second-level pulse; the battery with the structure of the present invention can operate in a wide temperature range from -40°C to 80°C; in addition, using a 9-series nickel cobalt manganese lithium oxide cathode high-nickel material + a negative electrode high-silicon carbon composite negative electrode system, the energy density of the battery can reach at least 270 Wh / Kg.

[0034] Preferably, the following relationship is satisfied between a% and the ratio A1 / B1: 2.5 ≤ |a * A1 / B1| ≤ 36.

[0035] Furthermore, one end of the battery cell with the positive electrode empty foil area is the positive electrode end, and one end of the battery cell with the negative electrode empty foil area is the negative electrode end;

[0036] The negative electrode end has a first outer ring cutting area and a first inner ring cutting area. Centered on the axis of the battery cell, the first outer ring cutting area and the first inner ring cutting area form a concentric ring structure. The position of the first inner ring cutting area is close to the axis of the battery cell, and the position of the first outer ring cutting area is at the edge of the battery cell;

[0037] The positive electrode end has a second outer ring cutting area and a second inner ring cutting area. Centered on the axis of the battery cell, the second outer ring cutting area and the second inner ring cutting area form a concentric ring structure. The position of the second inner ring cutting area is close to the axis of the battery cell, and the position of the second outer ring cutting area is at the edge of the battery cell..

[0038] Furthermore, the battery satisfies at least one of the following conditions:

[0039] (1) The radial cutting width of the first outer ring cutting area is d1, and the remaining height after cutting is h2, d1 = 0.1 - 1 mm, h2 = 1 - 4 mm;

[0040] (2) The radial cutting diameter of the first inner ring cutting area is D1, and the remaining height after cutting is h3, D1 = 2 - 5 mm, h3 = 1 - 4 mm;

[0041] (3) The radial cutting width of the second outer ring cutting area is d2, and the remaining height after cutting is h4, where d2 = 0.3 - 1 mm and h4 = 1.3 - 5 mm;

[0042] (4) The radial cutting diameter of the second inner ring cutting area is D2, and the remaining height after cutting is h5, where D2 = 2 - 5 mm and h5 = 1.3 - 5 mm.

[0043] Furthermore, the innermost ring of the battery cell is a diaphragm air coil, and the number of turns of the diaphragm air coil is in the range of 1.5 - 10 turns. The diaphragm air coil with 1.5 - 10 turns provides internal support for the battery cell to prevent the collapse of the central hole.

[0044] Furthermore, the battery further includes an electrolyte, and the electrolyte includes an additive nitrile compound; the nitrile compound is selected from at least one of mononitrile alkane compounds, dinitrile alkane compounds, trinitrile alkane compounds, ether nitriles, isonitriles, alkenenitriles, isocyanic acid, cyanuric acid, and isocyanuric acid, and among them, the dinitrile alkane compounds are preferably succinonitrile, adiponitrile, glutarodinitrile, pimelonitrile, and 1,2 - dicyanoacetylene.

[0045] On the other hand, the present invention provides an electrical device including a lithium - ion full - pole - ear cylindrical secondary battery as described in any one of the above.

[0046] Beneficial technical effects: By improving the full - pole - ear design and the negative electrode paste design, the present invention can significantly reduce the resistance, thereby greatly reducing the heat generation of the battery. The resistance of the full - pole - ear battery can be reduced by at least 70%, the working temperature rise can be reduced by at least 30%, the total energy throughput of the battery can be increased by at least 80%, and it also supports a charging rate of ≥3C, having excellent technical effects; the battery of the present invention has good heat dissipation, high energy density, excellent large - rate fast - charge and fast - discharge cycle performance, and good safety performance. Description of the Drawings

[0047] Figure 1 It is a schematic structural diagram of the negative electrode sheet of a lithium - ion full - pole - ear cylindrical secondary battery;

[0048] Figure 2 It is a schematic structural diagram of the positive electrode sheet of a lithium - ion full - pole - ear cylindrical secondary battery;

[0049] Figure 3 It is a schematic axial sectional structural diagram of the battery cell of a lithium - ion full - pole - ear cylindrical secondary battery;

[0050] Figure 4 It is a schematic top - view structural diagram of the battery cell of a lithium - ion full - pole - ear cylindrical secondary battery;

[0051] Figure 5 It is a schematic structural diagram of the positive electrode sheet and the negative electrode sheet of a traditional pole - ear cylindrical battery, where ① is the positive electrode sheet and ② is the negative electrode sheet;

[0052] Figure 6 Graph showing the linear relationship between the logarithm of the battery discharge current and the logarithm of the temperature rise coefficient for Examples 1-2 and Comparative Example 1;

[0053] Figure 7 Graph showing the curve relationship between the battery discharge current and the temperature rise coefficient for Examples 1-2 and Comparative Example 1. Detailed implementation manners

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below 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 description of at least one exemplary embodiment below is actually only illustrative and in no way restricts the present invention and its application or use. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0055] Unless otherwise specifically stated, the numerical values set forth in these embodiments do not limit the scope of the present invention. Technologies and methods known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies and methods should be regarded as part of the specification. In all examples shown and discussed herein, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.

[0056] The experimental methods without specific conditions in the following embodiments 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.

[0057] The meanings of the respective letters involved in the following embodiments are shown in Table 1 below.

[0058] Table 1 Meanings of each letter in the present invention

[0059]

[0060]

[0061] Example 1

[0062] This case is a 4Ah lithium-ion full-pole-ear cylindrical secondary battery, including a battery cell and a housing;

[0063] The battery cell includes a positive electrode sheet (length 1529 mm, width 60 mm, thickness 80 mm), a first separator (length 1662 mm, width 65 mm, thickness 12 mm), a negative electrode sheet (length 1584 mm, width 62 mm, thickness 100 mm), and a second separator (length 1694 mm, width 65 mm, thickness 12 mm) stacked in sequence and wound into a shape.

[0064] During stacking, the first separator and the second separator reserve a length of 13 mm at the start section of winding. The positive electrode sheet is wound inside along the length direction to form a wound battery cell. The reserved lengths of the two separators form 2 empty winding turns of the separator in the innermost circle. The number of winding turns of the positive electrode sheet of the battery cell is 25 turns, and the number of winding turns of the negative electrode sheet is 26 turns.

[0065] The schematic diagram of the axial sectional structure of the battery cell is as shown in Figure 3 shown, and the schematic diagram of the radial sectional structure of the battery cell is as shown in Figure 4 shown. One end of the wound battery cell with the positive electrode empty foil area is the positive electrode end, and one end with the negative electrode empty foil area is the negative electrode end:

[0066] The negative electrode end has a first outer ring cutting area and a first inner ring cutting area. Centered on the axis of the battery cell, the first outer ring cutting area and the first inner ring cutting area form a concentric ring structure. The position of the first inner ring cutting area is close to the axis of the battery cell, and the position of the first outer ring cutting area is at the edge of the battery cell. The radial cutting width d1 of the first outer ring cutting area is 1 mm, and the remaining height after cutting is h2 = 4.5 mm (the height before folding and stacking to form the negative electrode tab). The radial cutting diameter of the first inner ring cutting area is D1 = 3.5 mm, and the remaining height after cutting is h3 = 2 mm;

[0067] The positive electrode end has a second outer ring cutting area and a second inner ring cutting area. Centered on the axis of the battery cell, the second outer ring cutting area and the second inner ring cutting area form a concentric ring structure. The position of the second inner ring cutting area is close to the axis of the battery cell, and the position of the second outer ring cutting area is at the edge of the battery cell. The radial cutting width of the second outer ring cutting area is d2 = 1 mm, and the remaining height after cutting is h4 = 5.5 mm (the height before folding and stacking to form the negative electrode tab). The radial cutting diameter of the second inner ring cutting area is D2 = 3.5 mm, and the remaining height after cutting is h5 = 2 mm;

[0068] The schematic diagram of the negative electrode sheet is as shown in Figure 1As shown in the figure, it includes a negative electrode current collector (made of copper foil), and a negative electrode paste coating area and a negative electrode bare foil area (without coating) located on two surfaces of the negative electrode current collector. The two wide sides of the negative electrode sheet are respectively named the negative electrode winding starting end and the negative electrode winding ending end. A certain length is cut off from the edges of the two long sides of the negative electrode bare foil area, and the two wide sides of the remaining negative electrode bare foil area are respectively named the first starting end and the first ending end. The length between the first starting end and the negative electrode winding starting end is a1 = 130 mm, the distance between the first ending end and the negative electrode winding ending end is b1 = 65 mm, and the height of the negative electrode bare foil area is h0 = 5.5 mm;

[0069] The schematic structural diagram of the positive electrode sheet is as Figure 2 shown in the figure, it includes a positive electrode current collector (made of aluminum foil), and a positive electrode paste coating area and a positive electrode bare foil area (without coating) located on two surfaces of the positive electrode current collector. The two wide sides of the positive electrode sheet are respectively named the positive electrode winding starting end and the positive electrode winding ending end. A certain length is cut off from the edges of the two long sides of the positive electrode bare foil area, and the two wide sides of the remaining positive electrode bare foil area are respectively named the second starting end and the second ending end. The length between the second starting end and the positive electrode winding starting end is a2 = 125 mm, the distance between the second ending end and the positive electrode winding ending end is b2 = 60 mm, and the height of the positive electrode bare foil area is h1 = 7.5 mm;

[0070] The edge where the positive electrode paste coating area is connected to the positive electrode bare foil area has an insulating coating area formed by coating inorganic ceramics. The inorganic ceramics include 60 wt% aluminum oxide, 20 wt% silicon dioxide, 10 wt% titanium dioxide, 7 wt% zirconium dioxide, and 3 wt% zinc oxide. The average particle size D50 of the inorganic ceramics is 1 μm. The width direction of the insulating coating area is arranged along the width direction of the positive electrode sheet, and the width of the insulating coating area accounts for 1% of the width of the entire positive electrode sheet;

[0071] Among them, the negative electrode paste forming the negative electrode paste coating area includes 93 wt% artificial graphite, 3 wt% silicon-oxygen material, 1 wt% conductive agent acetylene black, and 3 wt% negative electrode binder polyacrylic acid. The specific surface area of the negative electrode sheet is 1.3 m 2 / g;

[0072] Among them, the positive electrode paste forming the positive electrode paste coating area includes 95 wt% LiNi 0.85 Co 0.05 Mn 0.07 Al 0.03O2, 1.1 wt% carbon nanotube conductive agent, 2.2 wt% Super-P (conductive carbon black), and 1.7 wt% PVDF binder. The specific surface area of the positive electrode sheet is 21.8 m 2 / g.

[0073] The battery internal resistance, temperature rise coefficient at 10C rate, 500-cycle life, and specific energy data are shown in Table 2.

[0074] Example 2

[0075] This case is a 5Ah lithium-ion full-pole ear cylindrical secondary battery, and its structure refers to the battery structure of Example 1, including a battery cell and a housing. The specific parameters are as follows:

[0076] The battery cell includes a positive electrode sheet (length 1532 mm, width 60 mm, thickness 90 mm), a first separator (length 1665 mm, width 65 mm, thickness 12 mm), and a negative electrode sheet (length 1590 mm, width 62 mm, thickness 110 mm), and a second separator (length 1703 mm, width 65 mm, thickness 12 mm) stacked and wound in sequence;

[0077] When stacking, a length of 13 mm is reserved at the starting section of the winding for the first separator and the second separator. The positive electrode sheet is wound inside along the length direction to form a wound battery cell. The reserved lengths of the two separators form 2 turns of separator empty winding in the innermost circle. The number of winding turns of the positive electrode sheet of the battery cell is 24 turns, and the number of winding turns of the negative electrode sheet is 25 turns;

[0078] The axial cross-sectional structure schematic diagram of the battery cell is as shown in Figure 3 shown, and the radial cross-sectional structure schematic diagram of the battery cell is as shown in Figure 4 shown. One end of the wound battery cell with the positive electrode empty foil area is the positive electrode end, and one end with the negative electrode empty foil area is the negative electrode end:

[0079] The negative electrode end has a first outer ring cutting area and a first inner ring cutting area. Taking the axis of the battery cell as the center, the first outer ring cutting area and the first inner ring cutting area form a concentric ring structure. The position of the first inner ring cutting area is close to the axis of the battery cell, and the position of the first outer ring cutting area is at the edge of the battery cell; the radial cutting width d1 of the first outer ring cutting area is 1 mm, and the remaining height after cutting is h2 = 4 mm (the height before folding and stacking to form the negative electrode pole ear); the radial cutting diameter of the first inner ring cutting area is D1 = 3.5 mm, and the remaining height after cutting is h3 = 2 mm;

[0080] The positive extreme end has a second outer ring excision area and a second inner ring excision area. Centered on the axis of the battery cell, the second outer ring excision area and the second inner ring excision area form a concentric ring structure. The position of the second inner ring excision area is close to the axis of the battery cell, and the position of the second outer ring excision area is at the edge of the battery cell. The radial excision width of the second outer ring excision area is d2 = 1 mm, and the remaining height after excision is h4 = 5 mm (the height before folding and stacking to form the negative electrode tab). The radial excision diameter of the second inner ring excision area is D2 = 3.5 mm, and the remaining height after excision is h5 = 2 mm.

[0081] The schematic structural diagram of the negative electrode sheet is as Figure 1 shown, and it includes a negative electrode current collector (made of copper foil) and a negative electrode slurry coating area and a negative electrode bare foil area (without coating) located on two surfaces of the negative electrode current collector. The two wide sides of the negative electrode sheet are respectively named the negative electrode winding starting end and the negative electrode winding ending end. A certain length is respectively cut and removed from the edges of the two long sides of the negative electrode bare foil area. The two wide sides of the remaining length of the negative electrode bare foil area are respectively named the first starting end and the first ending end. The length between the first starting end and the negative electrode winding starting end is a1 = 125 mm, the distance between the first ending end and the negative electrode winding ending end is b1 = 60 mm, and the height of the negative electrode bare foil area is h0 = 5 mm.

[0082] The schematic structural diagram of the positive electrode sheet is as Figure 2 shown, and it includes a positive electrode current collector (made of aluminum foil) and a positive electrode slurry coating area and a positive electrode bare foil area (without coating) located on two surfaces of the positive electrode current collector. The two wide sides of the positive electrode sheet are respectively named the positive electrode winding starting end and the positive electrode winding ending end. A certain length is respectively cut and removed from the edges of the two long sides of the positive electrode bare foil area. The two wide sides of the remaining length of the positive electrode bare foil area are respectively named the second starting end and the second ending end. The length between the second starting end and the positive electrode winding starting end is a2 = 120 mm, the distance between the second ending end and the positive electrode winding ending end is b2 = 55 mm, and the height of the positive electrode bare foil area is h1 = 7 mm.

[0083] The edge where the positive electrode slurry coating area is connected to the positive electrode bare foil area has an insulating coating area formed by coating inorganic ceramics. The inorganic ceramics include 70 wt% aluminum oxide, 10 wt% silicon dioxide, 10 wt% titanium dioxide, 6 wt% zirconium dioxide, and 4 wt% zinc oxide. The average particle size D50 of the inorganic ceramics is 2 μm. The width direction of the insulating coating area is arranged along the width direction of the positive electrode sheet, and the width of the insulating coating area accounts for 3% of the entire width of the positive electrode sheet.

[0084] Among them, the negative electrode paste forming the negative electrode paste coating area includes 92 wt% artificial graphite, 4 wt% silicon oxide material, 1 wt% conductive agent acetylene black, and 3 wt% negative electrode binder polyacrylic acid. The specific surface area of the negative electrode sheet is 1.9 m 2 / g;

[0085] Among them, the positive electrode paste forming the positive electrode paste coating area includes 95.5 wt% LiNi 0.9 Co 0.05 Mn 0.05 O2, 1.1 wt% carbon nanotube conductive agent, 1.9 wt% Super-P (conductive carbon black) conductive agent, and 1.5 wt% polyvinylidene fluoride PVDF binder. The specific surface area of the positive electrode sheet is 23.6 m 2 / g.

[0086] The battery internal resistance, temperature rise coefficient at 10C rate, 500-cycle life, and specific energy data are shown in Table 2.

[0087] Example 3

[0088] The battery in this case has the same structure and parameters as those in Example 1. The difference is that the mass ratio of the silicon oxide material in the negative electrode paste is increased to 10%, and the rest remains unchanged.

[0089] Comparative Example 1

[0090] This case is a traditional tab 4Ah cylindrical lithium-ion 21700 battery: the length of the positive electrode sheet is 866 mm, and an empty foil area with a length of 6 mm is set in the middle position in the length direction of the electrode sheet for welding the positive tab; the length of the negative electrode sheet is 962 mm, and empty foil areas with a length of 15 mm are set at both the head and the tail for welding two negative tabs; a single-layer separator is placed between the positive electrode sheet and the negative electrode sheet, and the length of the single-layer separator is 1610 mm and the thickness is 12 μm;

[0091] The structure of the positive electrode sheet is as shown in Figure 5 Figure ① of, and includes a positive electrode current collector (made of aluminum foil) and positive electrode paste coating areas on both surfaces of the positive electrode current collector;

[0092] The structure of the negative electrode sheet is as shown in Figure 5 Figure ② of, and includes a negative electrode current collector (made of copper foil) and negative electrode paste coating areas on both surfaces of the negative electrode current collector;

[0093] Among them, the negative electrode paste forming the negative electrode paste coating area includes 94 wt% artificial graphite, 2 wt% silicon, 1 wt% conductive agent acetylene black, and 3 wt% negative electrode binder polyacrylic acid. The specific surface area of the negative electrode sheet is 1.6 m 2 / g;

[0094] Among them, 95 wt% of the positive electrode paste for forming the positive electrode paste coating area is LiNi 0.85 Co 0.05 Mn 0.1 O2, 1.1 wt% of carbon nanotube conductive agent, 2.2 wt% of Super-P (conductive carbon black) conductive agent, and 1.7 wt% of polyvinylidene fluoride PVDF binder. The specific surface area of the positive electrode sheet is 22.1 m 2 / g.

[0095] The internal resistance of the battery in this case, the temperature rise coefficient at 10C rate, the cycle life of 500 cycles, and the specific energy data are shown in Table 2.

[0096] [Test Example]

[0097] 1. Test method for the temperature rise performance of the battery: At room temperature of 25°C, charge the battery cells from 1C to 25C (current from 4A to 125A) until fully charged to SOC = 100%, and then charge at constant current and constant voltage until the current is less than 0.05C. Let it stand for 10 minutes, and then discharge the battery cells at a discharge rate of 10C until fully discharged to SOC = 0%. Monitor the temperature of the battery cells during the discharge process and directly cut off the discharge when the temperature reaches 80°C. Assume the total discharge time is t min. Then, the difference between the battery temperature at the end of discharge and the battery temperature at room temperature is 55°C (328.15K). Then, the temperature rise coefficient m = 328.15 / t, with the unit of K / min. Plot a curve with the logarithm of a series of discharge currents lg i as the abscissa and the logarithm of the temperature rise coefficient lg m as the ordinate. The result is as Figure 6 shown, showing a good linear relationship. The curve relationship between the discharge current i and the temperature rise coefficient m is as Figure 7 shown.

[0098] 2. Battery internal resistance test

[0099] The acquisition of the DC internal resistance of the battery includes: At the experimental temperature of 25°C, charge the cylindrical lithium-ion battery at a charging rate of 2C until the rated charging cut-off voltage of 4.2V, then charge at constant voltage until the current drops to 0.025C. Let it stand for 4 hours, and then discharge the cylindrical lithium-ion battery at a discharge rate of 2.5C for 10 seconds. Then, reduce the discharge rate to 0.25C and continue to discharge for 10 seconds. Finally, increase the discharge rate to 2.5C again and continue to discharge for 4 seconds. During the discharge process, record the voltage at the 18th second (V1) and the voltage at the 23rd second (V2). The DC internal resistance R is: R = (V1 - V2) / 2.25C, with the unit of milliohm.

[0100] 3. Cycle life

[0101] The test method for the 500-cycle retention rate is as follows:

[0102] Take a lithium-ion battery prepared according to any of the above embodiments, place it in a constant-temperature oven at 25°C for more than 4 hours, and conduct tests according to the following steps:

[0103] S1: Constant-current charge the battery to 4.2V under the condition of a 1.5C charge rate, and then perform constant-voltage charging until the current reaches 0.025C, and let it stand for more than 15 minutes; discharge the battery at a constant current of 10C until the voltage reaches 2.5V, and record the discharge capacity as the initial capacity, denoted as C0;

[0104] S2: Repeat the above S21 step 500 times; record the discharge capacity at the 500th cycle, denoted as C1;

[0105] S3: Calculate the discharge capacity retention rate after 500 cycles as C1 / C0×100%.

[0106] 4. The test results are shown in Table 2.

[0107] Table 2 Battery performance of each case

[0108]

[0109]

[0110] According to the above experimental results, it can be seen that the performance of the all-tab cylindrical lithium-ion battery of the present invention is significantly better than that of traditional batteries. Compared with the traditional tab structure, the internal resistance of the battery is reduced by 70%. While supporting a higher discharge rate, the working temperature rise of the battery is also reduced by 30%, making the energy release more complete. The energy release ratio over the entire life cycle is increased by 80% compared to traditional tab cells. The product of the present invention can perform continuous discharge of more than 100A, providing strong energy support for instantaneous high-power tools. The extremely low impedance supports a charging rate of ≥3C for the battery cell without affecting the cycle life; the ultra-strong extreme charging ability enables "super fast charging" from 0 to 80% of the capacity within 10 minutes. The lithium-ion battery with the structure of the present invention not only improves safety and cycle life but also better meets the usage requirements of consumers.

[0111] 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, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A lithium-ion all-terminal cylindrical secondary battery, characterized in that, It includes a battery cell and a housing; The battery cell is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet; The positive electrode sheet includes a positive electrode current collector, and a positive electrode paste coating area and a positive electrode bare foil area without coating on at least one of its surfaces; the negative electrode sheet includes a negative electrode current collector, and a negative electrode paste coating area and a negative electrode bare foil area without coating on at least one of its surfaces; The negative electrode paste coating area is formed by coating a negative electrode paste on at least one surface of the negative electrode current collector, and the negative electrode paste includes graphite and silicon-oxygen material; Name the two wide sides of the negative electrode sheet as the negative electrode winding starting end and the negative electrode winding ending end respectively, cut off a certain length from the edges of the two long sides of the negative electrode bare foil area, and name the two wide sides of the remaining length of the negative electrode bare foil area as the first starting end and the first ending end respectively; The length between the first starting end and the negative electrode winding starting end is a1, the distance between the first ending end and the negative electrode winding ending end is b1, and let the height of the negative electrode bare foil area be h0, then the following relationship is satisfied: 17 ≤ a1 / h0 ≤ 55, 5 ≤ b1 / h0 ≤ 25, and the units of a1, b1, and h0 are all mm.

2. The lithium-ion full-tab cylindrical secondary battery according to claim 1, characterized in that h0 is 0.18% - 0.45% of the total length of the negative electrode sheet; a1 accounts for 6.25% - 12% of the total length of the negative electrode sheet, and b1 accounts for 1.8% - 5.2% of the total length of the negative electrode sheet.

3. The lithium ion full-tab cylindrical secondary battery according to claim 2, wherein h0 = 3 - 6mm, a1 = 100 - 160mm, b1 = 30 - 70mm.

4. The lithium-ion full-pole-ear cylindrical secondary battery according to claim 1, wherein Cut off a certain length from the edges of the two long sides of the positive electrode bare foil area, and name the two wide sides of the remaining length of the positive electrode bare foil area as the second starting end and the second ending end respectively; The length between the second starting end and the positive electrode winding starting end is a2, the distance between the second ending end and the positive electrode winding ending end is b2, and let the height of the positive electrode bare foil area be h1, then h1 is 0.19% - 0.69% of the total length of the positive electrode sheet, a2 accounts for 6.7% - 12.7% of the total length of the positive electrode sheet, and b2 accounts for 1.6% - 6.15% of the total length of the positive electrode sheet.

5. A lithium-ion all-pole-ear cylindrical secondary battery according to claim 4, characterized in that, h1 = 3 - 9mm, a2 = 105 - 165mm, b2 = 26 - 80mm.

6. A lithium-ion all-pole-tab cylindrical secondary battery according to claim 1, characterized in that, The battery also satisfies at least one of the following conditions: (1) The total length of the positive electrode sheet is 1300 - 1550mm; (2) The total length of the negative electrode sheet is 1330 - 1600mm; (3) The separator includes a first separator and a second separator located on both sides of the negative electrode sheet, the length of the first separator is 1370 - 1675mm, and the length of the second separator is 1400 - 1710mm; (4) The coating area of the positive electrode paste coating region is 770 - 930 cm 2 ; (5) The coating area of the negative electrode paste coating region is 880 - 1023 cm 2 ; (5) The areal capacity of the positive electrode sheet is 2 - 2.7 mAh / cm 2 ; (6) The areal capacity of the negative electrode sheet is 2.1 - 2.85 mAh / cm 2 ; (7) At least one edge of the positive electrode paste coating area has an insulating coating area coated with inorganic ceramics, and the inorganic ceramics are selected from any one or a combination of aluminum oxide, manganese dioxide, magnesium oxide, silicon dioxide, titanium dioxide, zirconium dioxide, zinc oxide, iron(III) oxide, boehmite, calcite; And the average particle size D50 of the inorganic ceramic is 0.5 - 3 μm. The width direction of the insulating coating area is set along the width direction of the positive electrode sheet, and the width of the insulating coating area accounts for 1 - 3% of the width of the entire positive electrode sheet.

7. A lithium-ion all-pole-tab cylindrical secondary battery according to claim 1, characterized in that, For the battery, the temperature rise coefficient m and the discharge current i during the discharge process satisfy the following linear relationship: M = A1 * Z + B1; where Z = lg i, where i is the current during the discharge process of the battery, with the unit of ampere. The value of A1 ranges from 1.8 to 2.2; the value of B1 ranges from -1.8 to -2.5; the discharge rate is 2C - 25C; where M = lg m, where m is the temperature rise coefficient during the discharge process of the battery, with the unit of Kelvin per minute.

8. A lithium-ion all-pole-tab cylindrical secondary battery according to any one of claims 1-7, characterized in that, The mass percentage of the silicon-oxygen material in the negative electrode paste is a%, and a% = 1% - 30%.

9. The lithium-ion full-tab cylindrical secondary battery according to claim 8, wherein, The following relationship is satisfied between a% and the ratio A1 / B1: 2 ≤ |a * A1 / B1| ≤ 45.

10. A lithium-ion all-pole-ear cylindrical secondary battery according to claim 9, characterized in that, The following relationship is satisfied between a% and the ratio A1 / B1: 2.5 ≤ |a * A1 / B1| ≤ 36.

11. A lithium-ion full-tab cylindrical secondary battery according to claim 8, characterized in that, One end of the battery cell with the positive electrode empty foil area is the positive electrode end, and one end with the negative electrode empty foil area is the negative electrode end; The negative electrode end has a first outer ring cutting area and a first inner ring cutting area. Centered on the axis of the battery cell, the first outer ring cutting area and the first inner ring cutting area form a concentric ring structure. The position of the first inner ring cutting area is close to the axis of the battery cell, and the position of the first outer ring cutting area is at the edge of the battery cell; The positive electrode end has a second outer ring cutting area and a second inner ring cutting area. Centered on the axis of the battery cell, the second outer ring cutting area and the second inner ring cutting area form a concentric ring structure. The position of the second inner ring cutting area is close to the axis of the battery cell, and the position of the second outer ring cutting area is at the edge of the battery cell.

12. The lithium-ion full-tab cylindrical secondary battery according to claim 11, wherein, The battery satisfies at least one of the following conditions: (1) The radial cutting width of the first outer ring cutting area is d1, and the remaining height after cutting is h2. d1 = 0.1 - 1 mm, h2 = 1 - 4 mm; (2) The radial cutting diameter of the first inner ring cutting area is D1, and the remaining height after cutting is h3. D1 = 2 - 5 mm, h3 = 1 - 4 mm; (3) The radial cutting width of the second outer ring cutting area is d2, and the remaining height after cutting is h4. d2 = 0.3 - 1 mm, h4 = 1.3 - 5 mm; (4) The radial cutting diameter of the second inner ring cutting area is D2, and the remaining height after cutting is h5. D2 = 2 - 5 mm, h5 = 1.3 - 5 mm.

13. The lithium-ion full-tab cylindrical secondary battery according to claim 8, wherein, The innermost ring of the battery cell is a diaphragm empty coil, and the number of turns of the diaphragm empty coil is in the range of 1.5 - 10 turns.

14. A lithium-ion all-pole-tab cylindrical secondary battery according to claim 8, wherein The battery further includes an electrolyte, and the electrolyte includes an additive nitrile compound; the nitrile compound is selected from at least one of mononitrile alkane compounds, dinitrile alkane compounds, trinitrile alkane compounds, ether nitriles, isonitriles, alkenenitriles, isocyanic acid, cyanuric acid, and isocyanuric acid.

15. An electrical device, including a lithium-ion full-pole-ear cylindrical secondary battery according to any one of claims 1 - 14.

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