A high energy density 21650 full-tab cylindrical lithium ion battery and an electric device using the same

Abstract

This application relates to the field of lithium-ion battery technology, and in particular to a high-energy-density 21650 all-tab cylindrical lithium-ion battery and its power supply device. The cylindrical lithium-ion battery includes a cylindrical casing, a core housed within the cylindrical casing, and an electrolyte. The total height H1 of the cylindrical casing ranges from 63.5 to 66.5 mm, and the outer diameter D ranges from 20.6 to 21.5 mm. The discharge capacity C of the cylindrical lithium-ion battery under 25°C and 0.2C discharge conditions is... 0.2 With a capacity of 4900~5200mAh, it satisfies: K v =C 0.2 / V cell 212~236 mAh / cm 3 K s =C 0.2 / A cell 96~106 mAh / cm 2 , where V cell The external volume (cm) of the cylindrical shell is represented. 3 A cell The outer surface area (cm²) of the cylindrical shell is represented by the following value. 2 This application converts the external dimensions of a short-height cylindrical lithium-ion battery into its external volume V. cell and external surface area A cell And the discharge capacity C when discharged at a rate of 0.2C. 0.2 The parameters K are formed by combining the two. v and K s This avoids describing short-height cells solely using total height or capacity, while also limiting K... v and K s Within a suitable range, both the unit volume capacity load and the unit surface area capacity load are controlled, taking into account both capacity maintenance and heat dissipation area constraints.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, and in particular to a high-energy-density 21650 all-tab cylindrical lithium-ion battery and its power supply device. Background Technology

[0002] With the rapid development of new energy vehicles and high-power energy storage equipment, the market has placed higher demands on the energy density and safety performance of lithium-ion batteries. All-tab cylindrical lithium-ion batteries, by using the entire edge of the electrode as a conductive current collector, significantly shorten the electron transport path, enabling the battery to exhibit excellent electrical performance under high-rate charge and discharge. The all-tab structure fundamentally changes the thermodynamic characteristics of cylindrical batteries. Traditional cylindrical batteries primarily conduct heat radially to the sidewalls of the casing, while the efficient current collector network of all-tab batteries allows heat to converge axially at an extremely high speed to the battery end cap area. For batteries with specific dimensions (such as the short-height 21650 type), the axial heat conduction distance is short and the end-face heat dissipation load is extremely high. Relying solely on the geometric constraints of the external dimensions cannot accurately match the battery's electrochemical heat generation and physical heat dissipation capabilities under actual operating conditions.

[0003] Related technologies, such as Chinese patent application CN122178073A, disclose a cylindrical battery that establishes a specific relationship by combining parameters such as the thickness of the thinned region, battery volume, the ratio of the adapter area to the cell end face area, and battery capacity. However, the combined model of the above technologies is mainly based on the steady-state logic of gas pressure volume buffer and mechanical pressure relief valve opening. For 21650 short-height full-tab cylindrical batteries, due to their short height dimension, the axial thermal resistance decreases by an order of magnitude, making it impossible to guarantee the safety of this type of battery by relying solely on local component parameters such as the static adapter area ratio.

[0004] Therefore, there is an urgent need in this field for a design scheme suitable for short-height cylindrical lithium-ion batteries, which can achieve a balance between high energy density, high power output and thermal safety of short-height all-tab cylindrical batteries. Summary of the Invention

[0005] This application specifically provides a cylindrical lithium-ion battery, and more particularly a high-energy-density 21650 all-tab cylindrical lithium-ion battery, by converting the short and tall dimensions of the 21650 type into a volume V. cell and external surface area A cell And the discharge capacity C when discharged at a rate of 0.2C. 0.2 The parameters K are formed by combining the two systems. v and K s This avoids describing short-height cells solely using total height or capacity, while also limiting K... v and K sWithin a suitable range, the capacity load per unit volume and the capacity load per unit surface area are controlled together, taking into account both capacity retention and heat dissipation area constraints, so that the 21650 short-height battery can still maintain its capacity, rate discharge and thermal safety performance even when the height is reduced.

[0006] To achieve the above objectives, this application adopts the following technical solution: The first aspect of this application provides a high-energy-density 21650 all-tab cylindrical lithium-ion battery, comprising a cylindrical shell, a core housed within the cylindrical shell, and an electrolyte. The core is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet. The ends of the positive and negative electrode sheets are flattened to form a positive all-tab end face and a negative all-tab end face, respectively. The total height of the cylindrical shell is defined as H1, ranging from 63.5 to 66.5 mm. The outer diameter of the cylindrical shell is defined as D, ranging from 20.6 to 21.5 mm. The discharge capacity C of the cylindrical lithium-ion battery under 25°C and 0.2C discharge conditions is... 0.2 The cylindrical lithium-ion battery has a capacity of 4900~5200mAh and meets the following requirements: K v =C 0.2 / V cell 212~236 mAh / cm 3 , where V cell The external volume (cm) of the cylindrical shell is represented. 3 V cell =π×(D / 2)^2×H1 / 1000; K s =C 0.2 / A cell 96~106 mAh / cm 2 , where A cell The outer surface area (cm²) of the cylindrical shell is represented by the following value. 2 A cell =[π×D×H1+2π×(D / 2)^2] / 100.

[0007] In some possible embodiments, the high-energy-density 21650 full-tab cylindrical lithium-ion battery further includes a positive current collector and a negative current collector welded to both ends of the core along its axial direction. The positive current collector is welded to the positive full-tab end face, and the negative current collector is welded to the negative full-tab end face. The effective current-carrying cross-sectional area of ​​the positive current collector is 38~48 mm². 2 The equivalent contact area between the negative electrode current collector and the cylindrical shell is 25~32mm. 2 .

[0008] In one possible implementation, under conditions of constant current discharge at 25°C and 40A to 2.5V or safe cutoff at 80°C, the highest temperature T on the large surface of the sidewall of the cylindrical casing of the high-energy-density 21650 all-tab cylindrical lithium-ion battery is [not specified]. max ≤67℃, and the rate discharge temperature rise ΔT≤42℃.

[0009] In one possible implementation, the pulsed DC internal resistance (DCR) of the high energy density 21650 omni-tab cylindrical lithium-ion battery at 25°C and 50% SOC is... 50 ≤8.8mΩ.

[0010] In one possible implementation, the high-energy-density 21650 all-tab cylindrical lithium-ion battery maintains a capacity retention rate R0 at 40A, based on a discharge capacity of 1A at 25°C. C40 >97.0%.

[0011] In one possible implementation, the total height H1 of the cylindrical shell ranges from 64.7 to 65.5 mm, the outer diameter D ranges from 20.8 to 21.2 mm, and the ratio of H1 to D ranges from 3.06 to 3.14.

[0012] In one possible implementation, the external volume V of the cylindrical shell cell The range is 21.8~23.3cm 3 The outer surface area A of the cylindrical shell cell The range is 48.8~51.0 cm. 2 .

[0013] In one possible implementation, K v The range is 218~228 mAh / cm 3 K s 98~103 mAh / cm 2 .

[0014] In one possible implementation, the high-energy-density 21650 all-tab cylindrical lithium-ion battery, under constant current discharge conditions of 25°C and 40A, satisfies the following condition: temperature rise capacity load ratio 0 < ΔT / K. v ≤0.190℃·cm³ / mAh, and 0<T max / K s ≤0.68 ℃·cm² / mAh.

[0015] In one possible implementation, the pulsed DC internal resistance (DCR) of the high energy density 21650 omni-tab cylindrical lithium-ion battery at 25°C and 50% SOC is... 50 The range is 6.5~8.2 mΩ.

[0016] In one possible implementation, the 40A cycle energy retention rate R is based on a discharge capacity of 1A at 25°C. CE40 ≥91.2%.

[0017] A second aspect of this application provides an electrical device including the aforementioned high-energy-density 21650 all-tab cylindrical lithium-ion battery.

[0018] Compared with the prior art, this application has the following advantages: The first aspect of this application provides a high-energy-density 21650 all-tab cylindrical lithium-ion battery, which converts the external dimensions of a short-height cylindrical lithium-ion battery that meets specific total height and outer diameter of the casing into an external volume V. cell and external surface area A cell And the discharge capacity C when discharged at a rate of 0.2C. 0.2 The parameters K are formed by combining the two. v and K s This avoids describing short-height cells solely using total height or capacity, while also limiting K... v and K s Within a suitable range, both the unit volume capacity load and the unit external surface area capacity load are controlled, balancing capacity preservation and heat dissipation area constraints; furthermore, K... v and K s With T max ΔT, DCR 50 and R C40 By combining different technologies, we can avoid the problem of excessive temperature rise during 40A rate discharge caused by pursuing only 5Ah capacity, and ensure that the short-height battery can still maintain capacity, rate discharge and thermal safety performance under the condition of reduced height.

[0019] The second aspect of this application provides an electrical device including the aforementioned high-energy-density 21650 all-tab cylindrical lithium-ion battery, which can achieve longer battery life and faster charging capability with the same volume or weight. At the same time, due to the low internal resistance and low heat generation of the battery, the thermal management load is reduced and the operational stability and safety under high load are improved. Detailed Implementation

[0020] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. It should be understood that the specific embodiments described are merely used to explain this application and are not intended to limit this application.

[0021] In the description of the embodiments of this application, it should be noted that all scopes disclosed in this application are to be understood to encompass any and all subscopes included therein. For example, the stated scope "100~120" should be considered to include any and all subscopes that begin with a minimum value of 100 or greater and end with a maximum value of 120 or less, such as 100 to 110, or 110 to 120, or 105 to 115. Furthermore, all scopes disclosed in this application are also considered to include the endpoints of the scope, unless otherwise expressly stated. For example, the scope "between 110 and 120" or "110 to 120" or "110-120" should generally be considered to include the endpoints 110 and 120.

[0022] This application addresses a specific form factor, such as the short-height 21650 cylindrical lithium-ion battery. Due to its short axial thermal conduction distance and high end-face heat dissipation load, simply relying on the geometric constraints of its form factor cannot accurately match the battery's electrochemical heat generation and physical heat dissipation capabilities under actual operating conditions. Existing related technologies are not specifically designed for this short-height battery and have certain limitations. Therefore, there is an urgent need for a design scheme for this specific short-height cylindrical lithium-ion battery that can ensure its safety while achieving a balance between high energy density, high power output, and thermal safety. In other words, it should enable the 21650 short-height battery to maintain its capacity, rate discharge capability, and thermal safety performance even with a reduced height. Based on this, the technical solution adopted in this application is to convert the 21650 short-height form factor into a volume V. cell and external surface area A cell And the discharge capacity C when discharged at a rate of 0.2C. 0.2 The parameters K are formed by combining the two. v and K s This avoids describing short-height cells solely using total height or capacity, while also limiting K... v and K s Within a suitable range, both the unit volume capacity load and the unit external surface area capacity load are controlled, balancing capacity preservation and heat dissipation area constraints; furthermore, K... v and K s With T max ΔT, DCR 50 and R C40 The design avoids excessive temperature rise during 40A rate discharge due to solely pursuing 5Ah capacity, ensuring that the 21650 short-height battery can maintain capacity, rate discharge, and thermal safety performance even under reduced height conditions.

[0023] To achieve the above objectives, this application adopts the following technical solution: This application provides a high-energy-density 21650 all-tab cylindrical lithium-ion battery, comprising a cylindrical shell, a core housed within the cylindrical shell, and an electrolyte. The core is formed by winding a positive electrode, a separator, and a negative electrode. The ends of the positive and negative electrode are flattened to form a positive all-tab end face and a negative all-tab end face, respectively. The total height of the cylindrical shell is defined as H1, ranging from 63.5 to 66.5 mm. The outer diameter of the cylindrical shell is defined as D, ranging from 20.6 to 21.5 mm. The discharge capacity C of the cylindrical lithium-ion battery under 25°C and 0.2C discharge conditions is... 0.2 The cylindrical lithium-ion battery has a capacity of 4900~5200mAh and meets the following requirements: K v =C 0.2 / V cell 212~236 mAh / cm 3 , where V cell The external volume (cm) of the cylindrical shell is represented. 3 V cell =π×(D / 2)^2×H1 / 1000; K s =C 0.2 / A cell 96~106 mAh / cm 2 , where A cell The outer surface area (cm²) of the cylindrical shell is represented by the following value. 2 A cell =[π×D×H1+2π×(D / 2)^2] / 100.

[0024] It should be noted that this application limits the total height of the cylindrical lithium-ion battery casing to 63.5~66.5mm and the outer diameter to 20.6~21.5mm. For example, the total height is limited to any one or any two of the following values: 63.5mm, 64.0mm, 64.5mm, 65.0mm, 65.5mm, 66.0mm, and 66.5mm, and the outer diameter is limited to any one or any two of the following values: 20.6mm, 20.7mm, 20.8mm, 20.9mm, 21.0mm, 21.1mm, 21.2mm, 21.3mm, 21.4mm, and 21.5mm. For example, the 21650 type short-height cylindrical lithium-ion battery is different from conventional cylindrical batteries, and the technical solution is designed for short-height cylindrical cells with a specific diameter-to-height ratio. At the same time, the above-mentioned limited size range can match the internal volume of the casing with the core design, eliminate dimensional deviations in group assembly, and ensure module installation gap and positioning welding accuracy.

[0025] In addition, by converting the external dimensions of this type of cylindrical lithium-ion battery to V celland A cell and with discharge capacity C 0.2 Jointly establish parameter K v and K s K v and K s The physical definitions are equivalent to capacity per unit volume and capacity per unit external surface area, respectively, avoiding the use of only total height or capacity to describe short-height cells; secondly, by simultaneously limiting K... v and K s Within a suitable range, both the volumetric capacity load and the surface area capacity load are controlled, balancing capacity retention and heat dissipation area constraints. This allows short-height batteries to maintain a capacity of 4.9–5.2 Ah even with reduced height. While keeping the cylindrical shell dimensions, active material system, electrode width, and compaction density constant, the total amount of active material in the core can be varied by adjusting the coating amount per unit area of ​​the positive electrode active material and simultaneously adjusting the coating amount per unit area of ​​the negative electrode active material, thereby obtaining different C values. 0.2 During the adjustment process, the ratio of negative electrode capacity to positive electrode capacity, N / P, should be controlled between 1.03 and 1.10, for example, 1.06, to avoid excessive C. 0.2 As an independent variable detached from electrode structure and preparation process.

[0026] In some embodiments, the cylindrical lithium-ion battery further includes a positive current collector and a negative current collector welded to both ends of the winding core, wherein the positive current collector is welded to the positive electrode tab end face, and the negative current collector is welded to the negative electrode tab end face, and the effective current-carrying cross-sectional area of ​​the positive current collector is 38~48mm². 2 The preferred size is 40~46mm. 2 The equivalent contact area between the negative current collector and the casing is 25~32mm. 2 The preferred size is 27~30mm. 2 When the effective current-carrying cross-sectional area or equivalent contact area is too small, the local current density and contact resistance increase, which can easily lead to increased DCR and 40A discharge temperature rise; when the area is too large, it will increase the mass of the current collector and occupy the space at the end of the core.

[0027] In some embodiments, the cylindrical lithium-ion battery satisfies the condition that, under constant current discharge at 25°C and 40A to 2.5V or safe cutoff at 80°C, the highest temperature T on the large surface of the sidewall of the cylindrical casing is [not specified]. max ≤67℃, for example, it can be 63~67℃, and the rate discharge temperature rise ΔT≤42℃, for example, it can be 38~42℃.

[0028] It is understandable that the temperature rise during rate discharge is ΔT = T. max - T0, where T0 is the cell sidewall temperature before the start of rate discharge, T maxT is the highest surface temperature during the high-rate discharge process. max The readings are obtained simultaneously using a patch thermocouple and a thermal imager. The patch thermocouple is positioned at least at 1 / 2 the axial height of the cylindrical shell, 10 mm from the positive end, and 10 mm from the negative end. The higher of the highest value of the patch thermocouple and the highest value of the thermal imager's sidewall is taken as T. max Unless otherwise stated, the term "large surface" in this application refers to the circumferential sidewall of the cylindrical casing, as the circumferential sidewall has the largest area; therefore, it is called the large surface or sidewall large surface, i.e., the side surface or circumferential surface of the cylindrical casing. During high-rate discharge, cylindrical lithium-ion batteries generate Joule heat due to ohmic and polarization internal resistance, and the highest temperature T on the large surface of the casing sidewall is... max The discharge temperature rise ΔT is a direct thermal indicator characterizing the cell's heat generation level, internal resistance control effect, and heat dissipation capacity. By limiting T... max The requirement that ΔT be within a suitable range is to constrain the heat generated during discharge of short-height cylindrical batteries within an acceptable thermal safety range, avoiding cycle life degradation and decreased thermal stability due to excessive temperature rise. In this application, by quantitatively defining the heat generation characteristics and thermal safety boundaries of short-height cylindrical lithium-ion batteries, it is demonstrated that through the synergistic optimization of cell structure parameters and core design, this application effectively controls the temperature rise during high-current discharge while achieving the required capacity and rate performance, thus balancing high-rate output capability and safety performance.

[0029] In some embodiments, the cylindrical lithium-ion battery satisfies the pulsed DC internal resistance (DCR) at 25°C and 50% SOC. 50 ≤8.8mΩ.

[0030] It should be noted that the pulsed DC internal resistance directly determines the ohmic voltage drop and Joule heat generation during high-current charging and discharging. If the DCR... 50 Excessive heat will cause a severe voltage drop at the battery cell's terminals during high-rate discharge, resulting in insufficient power output and a significant increase in ohmic temperature rise ΔT, raising the maximum temperature T on the casing sidewall. max Exceeding the aforementioned suitable range accelerates electrolyte decomposition and SEI membrane degradation, and may even induce thermal runaway risks. Therefore, this application limits DCR... 50 If the resistance is below the threshold mentioned above, the DC internal resistance of the short-height cylindrical lithium-ion battery can be constrained to within the maximum allowable value, ensuring that it has sufficient load voltage retention capability and controlled heat generation level in high-rate applications.

[0031] Furthermore, the pulsed DC internal resistance (DCR) of the cylindrical lithium-ion battery at 25°C and 50% SOC is... 50The range is 6.5 to 8.2 mΩ, for example, it can be any value or any two values ​​among 6.5mΩ, 6.6mΩ, 6.7mΩ, 6.8mΩ, 6.9mΩ, 7.0mΩ, 7.1mΩ, 7.2mΩ, 7.3mΩ, 7.4mΩ, 7.5mΩ, 7.6mΩ, 7.7mΩ, 7.8mΩ, 7.9mΩ, 8.0mΩ, 8.1mΩ and 8.2mΩ.

[0032] In some embodiments, the cylindrical lithium-ion battery maintains a capacity retention rate R at 40A based on a discharge capacity of 1A at 25°C. C40 >97.0%, for example, it can be 97.2~99.0%.

[0033] It should be noted that R C40 It is a core quantitative indicator characterizing the rate performance and polarization control level of short- and high-density cylindrical lithium-ion batteries. During high-rate discharge, the cell capacity utilization rate is mainly affected by the IR voltage drop caused by the ohmic internal resistance and electrode polarization. If the internal resistance is too high or the lithium-ion diffusion kinetics are insufficient, the terminal voltage will drop to the cutoff voltage in a short time, resulting in the actual discharged capacity being significantly lower than the rated capacity. The IR value is calculated based on the low-rate (1A) standard capacity. C40 This eliminates the interference from absolute capacity differences between different cells, directly reflecting the capacity utilization and rate capability of short-height cylindrical lithium-ion batteries under higher rate conditions. If R C40 A low DCR indicates that the cell's effective usable capacity under high current load is severely insufficient, the terminal voltage drops rapidly, and it cannot meet the continuous power requirements of high-rate electrical devices. This is usually accompanied by a high DCR. 50 With a larger rate-dependent temperature rise ΔT. Therefore, by limiting R... C40 If the threshold is greater than the above threshold, the rate discharge capacity utilization of short-height cylindrical lithium-ion batteries can be constrained to an acceptable minimum level, ensuring that they can provide sufficient power and release sufficient effective capacity under high rate load.

[0034] Furthermore, R C40 The aforementioned pulsed DC internal resistance DCR 50 And the thermal performance parameters, including the highest temperature T on the large surface of the sidewall of the cylindrical shell. max The temperature rise ΔT during high-rate discharge is within a reasonable range, which supports each other and provides a quantifiable basis for judging whether the battery under test simultaneously meets the requirements of high-rate capacity output, low internal resistance and thermal safety.

[0035] In some possible embodiments, the total height H1 of the cylindrical shell ranges from 64.7 to 65.5 mm, the outer diameter D ranges from 20.8 to 21.2 mm, and the ratio of H1 to D ranges from 3.06 to 3.14.

[0036] In some possible embodiments, the external volume V of the cylindrical shell cell The range is 21.8~23.3cm 3 The outer surface area A of the cylindrical shell cell The range is 48.8~51.0 cm. 2 .

[0037] In some possible embodiments, K v The range is 218~228 mAh / cm 3 K s 98~103 mAh / cm 2 .

[0038] In one possible implementation, the high-energy-density 21650 all-tab cylindrical lithium-ion battery, under constant current discharge conditions of 25°C and 40A, satisfies the following condition: temperature rise capacity load ratio 0 < ΔT / K. v ≤0.190℃·cm³ / mAh, and 0<T max / K s ≤0.68 ℃·cm² / mAh.

[0039] It should be noted that these two sets of ratio limits, by respectively relating the battery volume capacity, external surface area capacity, and the maximum discharge temperature rise and overall temperature rise, constrain the matching relationship between heat generation and heat dissipation during constant current discharge of the battery from two dimensions: volume and heat dissipation surface area. This can not only avoid the risk of local overheating and thermal runaway caused by excessive heat generation per unit capacity, but also ensure that the heat dissipation surface area of ​​the battery can dissipate the generated heat in time, balance the internal temperature of the battery, suppress excessive temperature difference, and stabilize the thermal safety and cycle life under high current discharge at 25℃.

[0040] In some embodiments, the cylindrical lithium-ion battery achieves a 40A cycle energy retention rate R based on a discharge capacity of 1A at 25°C. CE40 ≥91.2%, for example, it can be 91.2~93.0%.

[0041] Understandably, R CE40 It is a comprehensive indicator characterizing the actual high-rate performance of short- and tall cylindrical lithium-ion batteries, along with capacity retention rate R. C40 Unlike other factors, the capacity retention rate reflects both the capacity utilization rate and the average discharge voltage level during high-rate discharge. If the DC internal resistance (DCR) is... 50 Excessive voltage or severe polarization causes a significant drop in terminal voltage at high rates. Even if a similar proportion of capacity is discharged, the reduced average discharge voltage will lead to a substantial decrease in actual output energy. Using a low-rate standard energy E... 1A Calculate R based on the baseline CE40This can eliminate the absolute energy difference between cells and directly quantify the reduction in actual usable output power of short-height cylindrical lithium-ion batteries under 40A high-rate conditions relative to standard conditions. If R CE40 An excessively low R value indicates that the battery cell experiences severe voltage sag and high ohmic losses under a 40A load, resulting in a significant shortage of energy available for the external load and substandard device range. This can be addressed by limiting R... CE40 If the threshold is greater than the above threshold, the high-rate energy output capability of short-height cylindrical lithium-ion batteries can be constrained to an acceptable minimum level, ensuring that they have both sufficient capacity utilization and controlled voltage retention capability under high current load.

[0042] In this application, the 21650 cylindrical lithium-ion battery refers to a cylindrical lithium-ion battery with a diameter of 21 mm and a height of 65 mm.

[0043] In some possible implementations, under constant current discharge conditions of 25°C and 40A, the cylindrical lithium-ion battery satisfies the temperature rise capacity load ratio ΔT / K. v Not higher than 0.190℃·cm 3 / mAh, and T max / K s Not higher than 0.68℃·cm 2 / mAh.

[0044] In some possible implementations, the cylindrical lithium-ion battery, after 100 cycles of charging at 25°C and 8A and discharging at 40A, exhibits a DCR (Discharge Rate of Change). 50 The growth rate shall not exceed 15%, and the increase in temperature rise ΔT of 40A discharge shall not exceed 5℃.

[0045] In some embodiments, the positive electrode sheet includes a positive current collector and a positive electrode material layer, the positive electrode material layer being disposed on at least one surface of the positive current collector. The positive electrode material layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode sheet can be prepared using methods conventional in the art.

[0046] The positive electrode active material includes layered high-nickel lithium transition metal oxide with a nickel content of 88 mol% to 93 mol%, such as NCM90. The conductive agent can be selected from any one or more of graphite, conductive carbon black, acetylene black, Ketjen black, and carbon nanotubes. The binder can usually be selected from any one or more of polyvinylidene fluoride, polyvinyl alcohol, and carboxymethyl cellulose.

[0047] In some embodiments, the positive electrode material layer further includes a solvent, such as one or more of N-methylpyrrolidone, dimethyl sulfoxide, and N,N-dimethylformamide.

[0048] The positive current collector is typically aluminum foil.

[0049] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode material layer, wherein the negative electrode material layer is disposed on at least one surface of the negative electrode current collector, and the negative electrode material layer includes a negative electrode material, a conductive agent, and a binder. The negative electrode sheet may also be prepared using methods conventional in the art.

[0050] The anode material may include any one or more of silicon-carbon anode materials, silicon-oxygen anode materials, and graphite anode materials; the conductive agent may include any one or more of graphite, conductive carbon black, carbon nanotubes, acetylene black, and carbon fiber; and the binder may include any one or more of polyacrylic acid, styrene-butadiene rubber, polypropylene, starch, polyvinylpyrrolidone, and polyethylene.

[0051] In some embodiments, the negative electrode material layer further includes a thickener and a solvent. The thickener may be, for example, one or more of carboxymethyl cellulose, hydroxypropyl cellulose, and polyacrylic acid, and the solvent may be any one of water or a mixture of water and a lower alcohol.

[0052] The negative electrode current collector can be a conventional negative electrode current collector in the art, such as copper foil.

[0053] In some embodiments, the electrolyte may be a conventional electrolyte used in batteries in the art, generally including non-aqueous solvents and lithium salts.

[0054] In some embodiments, the non-aqueous solvent may be a conventional non-aqueous solvent in the art, such as an ester solvent, and optionally any one or more of ethylene carbonate, dimethyl carbonate, fluoroethylene carbonate, ethylene sulfate, vinylene carbonate, diethyl carbonate, and methyl propyl carbonate.

[0055] In some embodiments, the lithium salt may be a conventional lithium salt in the art, such as any one or more of LiPF6, LiFSI, LiBF4, LiClO4, and LiCF3SO3.

[0056] In some embodiments, the electrolyte further includes film-forming additives, such as one or both of vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0057] In some embodiments, the diaphragm may be a composite diaphragm of a base membrane and a ceramic coating, wherein the base membrane is typically made of materials conventional in the art, such as polypropylene membrane or polyethylene membrane.

[0058] The second aspect of this application also provides an electrical device comprising the aforementioned high-energy-density 21650 all-tab cylindrical lithium-ion battery.

[0059] In some possible embodiments, this application may also provide a method for screening cylindrical lithium-ion batteries, comprising the following steps: (1) Measure the total height H1 and outer diameter D of the cylindrical shell of the battery under test, and calculate the external volume V of the cylindrical shell. cell and external surface area A cell ; (2) Under 25°C conditions, test the discharge capacity C of the battery under test when discharged at a rate of 0.2C. 0.2 And calculate K v =C 0.2 / V cell and K s =C 0.2 / A cell ; (3) Under 25℃ conditions, the highest temperature T of the battery under test during the 40A discharge process was tested. max Temperature rise ΔT; and DCR of the test cell at 50% SOC under 25°C conditions. 50 Test the capacity retention rate R at 40A based on 1A discharge capacity under 25℃ conditions. C40 ; (4) Determine that the total height H1 of the battery under test is in the range of 63.5~66.5mm, the outer diameter D is in the range of 20.6~21.5mm, and the discharge capacity C is... 0.2 When the range is 4.9~5.2Ah, K is satisfied. v K s The preset conditions, K v The range is 212~236mAh / cm³. 3 K s The range is 96~106mAh / cm³. 2 And determine that the battery under test satisfies T max ΔT, DCR 50 and R C40 One or more preset conditions, and the preset conditions for each parameter are as follows: T max ≤67℃, ΔT≤42℃, DCR 50 ≤8.8mΩ, R C40 If the result is greater than 97.0%, the battery under test is deemed to meet the requirements.

[0060] The following examples further illustrate this application. Unless otherwise stated, the dimensions, capacity, rate of return, temperature rise, and DCR in the examples and comparative examples were obtained under the same test conditions.

[0061] All raw materials used in the embodiments and comparative examples of this application are commercially available.

[0062] Example 1 This embodiment 1 provides a 21650 short-height full-tab cylindrical lithium-ion battery. The battery includes a cylindrical casing, a core, electrolyte, a cap assembly, a positive current collector, a negative current collector, and insulating components. The total height H1 of the cylindrical casing is 65.1 mm, the outer diameter D is 21.0 mm, the shoulder height H2 is 64.8 mm, and the lower end height H5 is 62.3 mm.

[0063] Positive electrode sheet A layered high-nickel lithium transition metal oxide with a nickel content of approximately 90 mol% was used as the positive electrode active material. The conductive agents included conductive carbon black and carbon nanotubes, the binder was polyvinylidene fluoride (PVDF), and the solvent was N-methylpyrrolidone (N-Methylpyrrolidone). Based on 100% of the total solid components of the positive electrode, the positive electrode active material comprised 97.25 wt%, conductive carbon black 1.50 wt%, carbon nanotubes 0.10 wt% (dry weight), and PVDF 1.15 wt%. PVDF was dissolved in N-methylpyrrolidone by stirring. Conductive carbon black and carbon nanotubes were added and dispersed. The positive electrode active material was then added in batches, and the mixture was degassed under vacuum to obtain the positive electrode slurry. The solid content of the positive electrode slurry was controlled at 72 wt% to 76 wt%, and the viscosity at 25°C was controlled at 4500 mPa·s to 6500 mPa·s.

[0064] The positive electrode slurry is coated on both sides of an aluminum current collector with a thickness of about 12 μm. After being dried in sections at 80℃, 100℃ and 120℃, it is rolled and cut to obtain the positive electrode sheet.

[0065] Negative electrode sheet Artificial graphite and silicon carbide materials are used as the negative electrode active materials. The conductive agents include conductive carbon black and carbon nanotubes, the thickener is a carboxymethyl cellulose-based thickener, the binder is a styrene-butadiene rubber-based binder, and the solvent is deionized water. Based on 100% of the total mass of the negative electrode solid components, the composition is as follows: artificial graphite 82.95 wt%, silicon carbide material 13.50 wt%, conductive carbon black 0.50 wt%, carbon nanotubes (dry weight) 0.25 wt%, carboxymethyl cellulose-based thickener 1.10 wt%, and styrene-butadiene rubber-based binder 1.70 wt%. The carboxymethyl cellulose-based thickener is dissolved in deionized water by stirring. The conductive agent is added and dispersed, followed by the addition of artificial graphite and silicon carbide materials and stirring. Finally, the styrene-butadiene rubber-based binder is added and stirred at low speed to obtain the negative electrode slurry. The solid content of the negative electrode slurry is controlled at 45 wt% to 50 wt%, and the viscosity at 25°C is controlled at 2500 mPa·s to 4500 mPa·s.

[0066] The negative electrode slurry is coated on both sides of the copper current collector, and then dried in sections at 80°C to 110°C, rolled and cut to obtain the negative electrode sheet.

[0067] A single-sided ceramic-coated polyolefin separator is used.

[0068] electrolyte It includes 15 wt% lithium salt, 82 wt% carbonate solvent and 3 wt% film-forming additive. The lithium salt includes 12 wt% LiPF6 and 2 wt% LiFSI, and the film-forming additive includes 1 wt% VC and 2 wt% FEC.

[0069] Assembly The positive electrode sheet, separator, negative electrode sheet, and separator are wound in a stacked sequence to form a core, ensuring that the negative electrode material area covers the positive electrode material area in the width direction, and the separator covers the negative electrode material area. After winding, the ends of the core are flattened to form a full-ear end face. The core is then installed into a cylindrical shell, completing the welding of the positive electrode current collector, welding of the negative electrode current collector, installation of insulating components, liquid injection, sealing, formation, aging, and capacity testing. In Example 1, the effective current-carrying cross-sectional area of ​​the positive electrode current collector is 42 mm². 2 The equivalent contact area between the negative current collector and the housing is 28mm². 2 The coating amount per unit area of ​​the positive and negative electrode sheets is based on 100% in Example 1, and the N / P ratio is 1.06.

[0070] After injection, the solution was allowed to stand at 25°C for 12 hours, and then at 45°C for 24 hours, before undergoing formation, aging, and volume fractionation. The volume fractionated to 0.2C was then determined. 0.2 It has a capacity of 5000mAh.

[0071] V in this embodiment 1 cell It is 22.55cm 3 A cell It is 49.88cm 2 K v 221.7mAh / cm 3 K s 100.2mAh / cm 2 .

[0072] Example 2 The only difference between Example 2 and Example 1 is that the total height H1 of the cylindrical shell is adjusted to 64.7mm, so that V cell It is 22.41cm 3 A cell It is 49.61cm 2 K v 223.1 mAh / cm 3 K s 100.8mAh / cm 2 All other conditions are the same as in Example 1.

[0073] Example 3 The only difference between Example 3 and Example 1 is that the total height H1 of the cylindrical shell is adjusted to 65.5mm, at which point V cell It is 22.69cm3 A cell It is 50.14cm 2 K v 220.4mAh / cm 3 K s 99.7mAh / cm 2 All other conditions are the same as in Example 1.

[0074] Example 4 The only difference between Example 4 and Example 1 is that the outer diameter D of the cylindrical shell is adjusted to 20.8 mm, at which point V cell It is 22.12cm 3 A cell It is 49.34cm 2 K v 226.0mAh / cm³ 3 K s 101.3mAh / cm 2 All other conditions are the same as in Example 1.

[0075] Example 5 The only difference between Example 5 and Example 1 is that the outer diameter D of the cylindrical shell is adjusted to 21.2 mm, at which point V cell It is 22.98cm 3 A cell It is 50.42cm 2 K v 217.6mAh / cm 3 K s 99.2mAh / cm 2 All other conditions are the same as in Example 1.

[0076] Example 6 The only difference between Example 6 and Example 1 is that the coating amount per unit area of ​​the positive electrode active material is reduced to 98.0% of that in Example 1, and the coating amount per unit area of ​​the negative electrode active material is simultaneously reduced, so that the N / P ratio remains at 1.06; the compaction density, width, and length of the positive and negative electrode sheets remain unchanged. Therefore, the 0.2C capacity C after capacity testing... 0.2 With a capacity of 4900mAh, K v 217.3mAh / cm 3 K s 98.2mAh / cm 2 Except for the coating amount adjustment mentioned above, all other conditions are the same as in Example 1.

[0077] Example 7 The only difference between Example 7 and Example 1 is that the coating amount per unit area of ​​the positive electrode active material is increased to 104.0% of that in Example 1, and the coating amount per unit area of ​​the negative electrode active material is simultaneously increased, maintaining the N / P ratio at 1.06; the compaction density, width, and length of the positive and negative electrode sheets remain unchanged. Therefore, the 0.2C capacity C after capacity testing... 0.2 It has a capacity of 5200mAh, K v 230.6mAh / cm 3 K s 104.3mAh / cm 2 Except for the coating amount adjustment mentioned above, all other conditions are the same as in Example 1.

[0078] Example 8 The only difference between Example 8 and Example 1 is that the effective current-carrying cross-sectional area of ​​the positive current collector is reduced from 42mm². 2 Increased to 48mm 2 The equivalent contact area between the negative current collector and the shell was reduced from 28mm. 2 Increased to 32mm 2 All other conditions are the same as in Example 1.

[0079] Example 9 The only difference between Example 9 and Example 1 is that the effective current-carrying cross-sectional area of ​​the positive current collector is increased from 42mm². 2 Reduced to 38mm 2 The equivalent contact area between the negative current collector and the shell was reduced from 28mm. 2 Reduced to 25mm 2 All other conditions are the same as in Example 1.

[0080] Example 10 The only difference between Example 10 and Example 1 is that the total height H1 of the cylindrical shell is adjusted to 64.7 mm and the outer diameter D is 20.8 mm; the coating amount per unit area of ​​the positive electrode active material is reduced to 102.0% of that in Example 1, and the coating amount per unit area of ​​the negative electrode active material is simultaneously reduced, so that the 0.2C capacity C after capacity testing is achieved. 0.2 The capacity is 5100mAh, at which point V cell It is 21.98cm 3 A cell It is 49.07cm 2 K v 232.0 mAh / cm 3 K s 103.9mAh / cm 2 All other conditions are the same as in Example 1.

[0081] Example 11 The only difference between Example 11 and Example 1 is that the total height H1 of the cylindrical shell is adjusted to 65.5 mm and the outer diameter D is 21.2 mm; and the coating amount per unit area of ​​the positive electrode active material is reduced to 99.0% of that in Example 1, while the coating amount per unit area of ​​the negative electrode active material is simultaneously reduced, so that the 0.2C capacity C after capacity testing is achieved. 0.2 The capacity is 4950mAh, at which point V cell It is 23.12cm 3 A cell It is 50.68cm 2 K v 214.1 mAh / cm 3 K s 97.7mAh / cm 2 All other conditions are the same as in Example 1.

[0082] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the total height H1 of the cylindrical shell is adjusted to 63.2 mm, so that V cell It is 21.89cm 3 A cell It is 48.62cm 2 K v 228.4mAh / cm 3 K s 102.8mAh / cm 2 All other conditions are the same as in Example 1.

[0083] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that the outer diameter D of the cylindrical shell is adjusted to 20.4 mm, at which point V cell It is 21.28cm 3 A cell It is 48.26cm 2 K v 235.0mAh / cm 3 K s 103.6mAh / cm 2 All other conditions are the same as in Example 1.

[0084] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that the coating amount per unit area of ​​the positive electrode active material is increased to 106.0% of that in Example 1, and the coating amount per unit area of ​​the negative electrode active material is simultaneously increased to maintain the N / P ratio at 1.06; the compaction density, width, and length of the positive and negative electrode sheets remain unchanged. Therefore, the 0.2C capacity C after capacity testing... 0.2 It has a capacity of 5300mAh, K v 235.1mAh / cm3 K s 106.3mAh / cm 2 Except for the coating amount adjustment mentioned above, all other conditions are the same as in Example 1.

[0085] Comparative Example 4 The only difference between Comparative Example 4 and Example 1 is that the effective current-carrying cross-sectional area of ​​the positive current collector is reduced from 42 mm². 2 Reduced to 30mm 2 The equivalent contact area between the negative current collector and the shell was reduced from 28mm. 2 Reduced to 18mm 2 All other conditions are the same as in Example 1.

[0086] Comparative Example 5 The only difference between Comparative Example 5 and Example 1 is that the homogenization time in an environment of 25±2℃ before 40A discharge is shortened from no less than 12 hours to 2 hours, and the effective current-carrying cross-sectional area of ​​the positive electrode current collector is reduced from 42 mm². 2 Reduced to 34mm 2 The equivalent contact area between the negative current collector and the casing remains 28mm². 2 All other conditions are the same as in Example 1.

[0087] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that the outer diameter D of the cylindrical shell is adjusted to 20.6 mm, the coating amount per unit area of ​​the positive electrode active material is increased to 105.0% of that in Example 1, and the coating amount per unit area of ​​the negative electrode active material is adjusted simultaneously, so that the 0.2C capacity C after capacity testing is achieved. 0.2 The capacity is 5250mAh, and the effective current-passing cross-sectional area of ​​the positive electrode current collector is increased from 42mm². 2 Reduced to 32mm 2 At this time, K v 239.1mAh / cm 3 K s 108.0mAh / cm 2 All other conditions are the same as in Example 1.

[0088] Comparative Example 7 The only difference between Comparative Example 7 and Example 1 is that the total height H1 of the cylindrical shell is adjusted to 64.0 mm and the outer diameter D is adjusted to 20.6 mm; the coating amount per unit area of ​​the positive electrode active material is reduced to 104.0% of that in Example 1, and the coating amount per unit area of ​​the negative electrode active material is simultaneously reduced, so that the 0.2C capacity C after capacity testing is achieved. 0.2 It has a capacity of 5200mAh, at which point V cell It is 21.33cm 3 A cell It is 48.08cm2 K v 243.8mAh / cm 3 K s 108.1mAh / cm 2 All other conditions are the same as in Example 1.

[0089] Comparative Example 8 The only difference between Comparative Example 8 and Example 1 is that the total height H1 of the cylindrical shell is adjusted to 66.8 mm and the outer diameter D is adjusted to 21.5 mm; the coating amount per unit area of ​​the positive electrode active material is reduced to 97.0% of that in Example 1, and the coating amount per unit area of ​​the negative electrode active material is simultaneously reduced, so that the 0.2C capacity C after capacity testing is achieved. 0.2 The capacity is 4850mAh, at which point V cell It is 24.25cm 3 A cell It is 52.38cm 2 K v 200.0mAh / cm 3 K s 92.6mAh / cm 2 All other conditions are the same as in Example 1.

[0090] Effect Example Parameter definition and formula H1 represents the total height of the cylindrical shell, in mm. D represents the outer diameter of the cylindrical shell, in mm.

[0091] V cell This indicates the external volume of the battery cell, in cm. 3 V cell =π×(D / 2)^2×H1 / 1000.

[0092] A cell This indicates the outer surface area of ​​the battery cell, in cm². 2 A cell =[π×D×H1+2π×(D / 2)^2] / 100.

[0093] C 0.2 This indicates the discharge capacity at 25℃ and 0.2C, expressed in mAh.

[0094] K v =C 0.2 / V cell The unit is mAh / cm³ 3 .

[0095] K s =C 0.2 / A cell The unit is mAh / cm³ 2 .

[0096] R C40 =C 40 / C 1A ×100%, where C 40 For a discharge capacity of 40A at 25℃, C 1A It has a discharge capacity of 1A at 25℃.

[0097] R CE40 =E 40 / E 1A ×100%, where E 40 At 25℃ and 40A discharge energy, E 1A The discharge energy is 1A at 25℃.

[0098] ΔT=T max -T0, where T0 is the cell sidewall temperature before the start of rate discharge, T max This represents the highest surface temperature during the high-rate discharge process.

[0099] DCR = ΔV / ΔI, where ΔV is the voltage difference before and after the pulse discharge, and ΔI is the pulse current step difference.

[0100] Performance testing methods Cell size measurement method At least three battery cells were tested in each embodiment and comparative example. Except for Comparative Example 5, the battery cells were placed in an environment of 25±2℃ for at least 12 hours before testing. The total height H1 of the cylindrical shell was measured using a height gauge or a two-dimensional measuring instrument with a resolution of not less than 0.01 mm, and three points were measured at approximately 120° intervals along the circumference, and the average value was taken. The outer diameter D was measured using an outside micrometer or a two-dimensional measuring instrument with a resolution of not less than 0.01 mm, and three points were measured along the axial direction at the middle and near both ends, and the average value was taken.

[0101] Test methods for effective flow cross-sectional area and equivalent contact area At least three battery cells must be tested. The testing equipment includes: a battery charge / discharge test cabinet, a dry disassembly environment with a dew point not higher than -40°C, precision cutting tools, dimethyl carbonate cleaning solution, a digital microscope or image measuring instrument, a standard ruler, image analysis software, and a micrometer with a resolution of not less than 0.001 mm.

[0102] Before testing, the battery cell was discharged at a constant current of 0.2C to 2.5V, allowed to stand for 30 minutes, and then disassembled in a dry environment. The core, positive current collector, negative current collector, and the bottom area of ​​the housing welded to the negative current collector were removed. The component under test was cleaned with dimethyl carbonate to remove residual electrolyte and deposits, and then dried at 25±2℃ for no less than 2 hours.

[0103] The effective current-carrying cross-sectional area S of the positive current collectorpos The determination is performed as follows: The positive current collector is laid flat and fixed, with one side of the positive electrode tab facing upwards. A digital microscope or image measuring instrument is used to acquire a projected image of the positive current collector, and the pixel dimensions are calibrated using a standard ruler. Along the main current direction from the positive electrode tab end face to the external conductive connection, the narrowest metal current-carrying position of each parallel conductive section is determined, and its minimum effective width b is measured. i Then, use a micrometer to measure the metal thickness t at the corresponding location. i Openings, notches, insulation coverage areas, cracked areas, and discontinuous areas are not included in the effective width. The effective current-carrying cross-sectional area S of the positive current collector. pos Calculate S using the following formula: pos =Σ(b i ×t i ); where b i t represents the minimum effective width of the i-th parallel conductive part, in mm; i S represents the metal thickness at the location corresponding to the i-th parallel conductive part, in mm; pos The unit is mm 2 .

[0104] The equivalent contact area S between the negative current collector and the cylindrical shell is neg The determination is performed as follows: The welded connection area between the negative current collector and the bottom of the housing is used as the test object. The weld is peeled and unfolded along the interface to expose the weld fusion marks or weld nugget marks. A digital microscope or image measuring instrument is used to acquire the orthographic projection image of the weld interface, and the pixel size is calibrated using a standard ruler. Image analysis software is used to identify the boundaries of the continuous fusion zone or weld nugget zone. Spatter, indentations, areas that are oxidized and blackened but have not formed a metal bond, and unfused areas are subtracted to obtain the projected area A of each effective weld area. i The equivalent contact area S between the negative current collector and the cylindrical shell is... neg Calculate S using the following formula: neg =ΣA i , where A i The projected area of ​​the i-th effective welding region is expressed in mm. 2 S neg The unit is mm 2 .

[0105] In the same cell, all parallel conductive parts of the positive current collector are included in S. pos The calculations include all effective welding areas between the negative electrode current collector and the cylindrical shell in S. neg Calculation. Take S from 3 battery cells. pos The arithmetic mean is used as the effective current-carrying cross-sectional area of ​​the positive current collector. The S values ​​of the three cells are taken as... negThe arithmetic mean is used as the equivalent contact area for welding the negative current collector to the cylindrical shell.

[0106] 0.2C Capacity and Energy Testing At least three battery cells were tested in each embodiment and comparative example. Except for Comparative Example 5, the battery cells were placed in an environment of 25±2℃ for at least 12 hours, charged at a constant current of 0.2C to 4.2V, then charged at a constant voltage of 4.2V until the cutoff current was no greater than 0.05C, and left to stand for 30 minutes; subsequently, they were discharged at a constant current of 0.2C to 2.5V. The voltage and current sampling intervals of the test system were both no greater than 1 second. The 0.2C discharge capacity C... 0.2 This represents the cumulative discharge capacity at discharge cutoff.

[0107] 25℃, 1A reference discharge test The cell under test was fully charged at a 0.2C rate, allowed to stand for 30 minutes, and then discharged at a constant current of 1A to 2.5V. The discharge capacity C at 1A was recorded. 1A 1A discharge energy E 1A The discharge platform voltage and discharge time, and the voltage and current sampling intervals are all no greater than 1 second. At least three cells are tested in each embodiment and comparative example, and the average value is taken as R. C40 and R CE40 Calculation benchmark.

[0108] 25℃, 40A discharge rate capacity retention, energy retention and temperature rise test Except for Comparative Example 5, the battery cells under test were placed in an environment of 25±2℃ for at least 12 hours. At least three cells were tested in each example and comparative example. The cells were fully charged using a constant current and constant voltage regime at 0.2C, and after standing for 30 minutes, discharged to 2.5V using a constant current of 40A. If the temperature at any measuring point on the surface of the battery cell reached 80℃, the discharge was stopped at 80℃ as a safe cutoff condition. The sampling interval for voltage, current, and surface-mount thermocouples was no greater than 1 second, and the sampling interval for the thermal imager was no greater than 5 seconds. The 40A discharge capacity C was recorded. 40 40A discharge energy E 40 Discharge time, voltage curve, and temperature curve. The judgment criterion is R. C40 Not less than 97.0%, R CE40 Not less than 91.2%, T max The temperature should not exceed 67℃ or the ΔT temperature should not exceed 42℃.

[0109] SOC-DCR test At least three cells were tested in each embodiment and comparative example. The cells were fully charged at 25±2℃ using a 0.2C regime and allowed to rest for 60 minutes. The cells were then adjusted to the target SOC using constant current discharge, with target SOCs including at least 100%, 80%, 50%, 30%, and 10%. After resting for 30 minutes at each SOC point, a 10s, 40A discharge pulse was applied. The voltage and current sampling interval was no greater than 0.1s. The voltage V0 before the pulse and the voltage V1 at the end of the pulse were recorded. The DCR was calculated using DCR = ΔV / ΔI, where ΔV = V0 - V1, and ΔI is the difference between the pulse current and the resting current. The criterion was that the DCR at 50% SOC should not exceed 8.8mΩ, preferably between 6.5mΩ and 8.2mΩ.

[0110] Synchronous temperature testing of thermal imager and patch thermocouple The 40A rate test employs simultaneous temperature measurement using a patch thermocouple and a thermal imager. The patch thermocouple has at least three measuring points: the first point is located at half the axial height H1 of the cylindrical shell; the second point is located 10 mm from the positive terminal; and the third point is located 10 mm from the negative terminal. The thermal imager is positioned directly opposite the cell sidewall, with an emissivity set to 0.90 to 0.95, and a sampling interval of no more than 5 seconds; the patch thermocouple sampling interval is no more than 1 second. max Take the higher of the highest value of the patch thermocouple and the highest value of the thermal imager sidewall.

[0111] This application also includes a reverse identification method starting from the 21650 finished battery cell, comprising the following steps: Measure H1 and D, calculate V cell and A cell Subsequently, the discharge capacity C at 25°C and 0.2C was tested. 0.2 And calculate K v =C 0.2 / V cell and K s =C 0.2 / A cell T was then obtained through a 40A discharge rate test. max And ΔT, DCR was obtained through a 50% SOC pulse test. 50 R was calculated using 1A and 40A discharge data. C40 and R CE40 .

[0112] A sample is deemed to fall within the protection window requested in this application if it simultaneously meets the following conditions: H1 is 63.5 mm to 66.5 mm, D is 20.6 mm to 21.5 mm; C 0.2 With a capacity ranging from 4900mAh to 5200mAh, K v 212mAh / cm 3 Up to 236mAh / cm 3Ks is 96mAh / cm 2 Up to 106mAh / cm 2 40A discharge T max Not exceeding 67℃ or ΔT not exceeding 42℃; DCR 50 Not higher than 8.8mΩ or R C40 No less than 97.0%.

[0113] The parameters and effect data of Examples 1-11 and Comparative Examples 1-8 are shown in Table 1: Table 1 As can be seen from the data in Examples 1-3, when H1 is adjusted from 65.1mm to 64.7mm, V cell From 22.55cm 3 It dropped to 22.41cm 3 A cell From 49.88cm 2 It dropped to 49.61cm 2 In C 0.2 While maintaining a capacity of 5000mAh, K v Increased to 223.1mAh / cm 3 K s Increased to 100.8mAh / cm³ 2 DCR 50 It is 7.3mΩ, T max When the temperature rises to 65.6℃, ΔT rises to 40.6℃, still falling within the thermal safety window. When H1 is adjusted to 65.5mm, K... v Reduced to 220.4mAh / cm 3 K s Reduced to 99.7mAh / cm³ 2 T max The temperature dropped to 64.5℃. This indicates that an excessively low H1 will increase the capacity load per unit volume and per unit surface area, thus increasing the rate of heating pressure; however, within the range of 64.7mm to 65.5mm, the capacity load and temperature rise can still be maintained simultaneously.

[0114] Data from Examples 1, 4, and 5 show that when D is adjusted from 21.0 mm to 20.8 mm, V cell It dropped to 22.12cm 3 A cell It dropped to 49.34cm 2 K v Increased to 226.0mAh / cm³ 3 K s Increased to 101.3mAh / cm 2 DCR 50 It is 7.5mΩ, Tmax When the temperature rises to 66.2℃, ΔT rises to 41.2℃, approaching but not exceeding the preferred temperature rise threshold. When D is adjusted to 21.2mm, V... cell and A cell They increased to 22.98cm respectively. 3 and 50.42cm 2 K v Reduced to 217.6mAh / cm³ 3 K s Reduced to 99.2mAh / cm³ 2 T max The temperature dropped to 64.2℃. This indicates that the outer diameter directly changes the capacity carrying volume and the side wall heat dissipation area. A diameter of 20.8mm to 21.2mm can balance the compatibility of short and tall platforms and the heat dissipation of 40A.

[0115] As can be seen from the data of Examples 1, 6 and 7, C 0.2 When the capacity is adjusted from 5000mAh to 4900mAh, V cell and A cell Unchanged, K v Reduced to 217.3mAh / cm 3 K s Reduced to 98.2mAh / cm³ 2 DCR 50 It is 6.9mΩ, T max The temperature is 63.8℃, indicating a relatively large margin for temperature rise during rate scaling. 0.2 When adjusted to 5200mAh, K v Increased to 230.6mAh / cm³ 3 K s Increased to 104.3mAh / cm 2 DCR 50 Increased to 8.0mΩ, T max The temperature rose to 66.4℃, still meeting the protection window. This indicates that increasing capacity will simultaneously increase the reaction load per unit volume and the heat dissipation load per unit surface area; the capacity range of 4.9Ah to 5.2Ah requires consideration of K... v K s DCR and T max The two factors are mutually exclusive and cannot be judged solely based on capacity.

[0116] As can be seen from the data of Examples 1, 8, and 9, in H1, D, C 0.2 K v and K s When kept consistent, DCR 50 The R value decreased from 7.2 mΩ to 6.6 mΩ. C40 Rising to 98.8%, R CE40 Rising to 92.8%, T maxThe temperature dropped from 65.0℃ to 63.8℃, indicating that a decrease in the current collector path resistance directly reduces the ohmic heat generated during a 40A discharge. (DCR) 50 When R increases to 8.1mΩ, C40 It dropped to 97.5%, R CE40 Dropped to 91.5%, T max It rose to 66.3℃, but still did not exceed 67℃. Due to K... v and K s No change; this group of differences excludes the influence of capacity load variations and can separately explain the contribution of the collector path and DCR to the rate-driven temperature rise. This indicates that under the same capacity load, DCR... 50 It is a key parameter for the rate-dependent temperature rise, and its upper limit should not exceed 8.8mΩ.

[0117] By comparing the data from Example 10, Example 11, Comparative Example 7, and Comparative Example 8, it can be seen that Example 10 simultaneously uses H1=64.7mm, D=20.8mm, and C 0.2 =5100mAh, making K v Reaching 232.0 mAh / cm³ 3 K s Reaching 103.9mAh / cm³ 2 T max At 66.8℃, it can still pass through the protective T max Threshold. Example 11 uses H1=65.5mm, D=21.2mm and C 0.2 =4950mAh, K v and K s The values ​​decreased to 214.1 mAh / cm³. 3 and 97.7mAh / cm 2 T max The temperature was 63.5℃. The K value for Comparative Example 7 was... v and K s The capacity was increased to 243.8 mAh / cm³. 3 and 108.1mAh / cm 2 K in comparison ratio 8 v and K s Then it dropped to 200.0 mAh / cm³. 3 and 92.6mAh / cm 2 All of them deviated from the window. Although Comparative Example 8 met the thermal performance requirements, its capacity was lower than 4900mAh, which deviated from the high energy density design target, proving that the window of this application is a balance range between capacity and thermal safety, rather than the lower the better.

[0118] By comparing the data from Example 7, Comparative Example 3, and Comparative Example 6, it can be seen that C 0.2 When it reaches 5200mAh, K v 230.6mAh / cm3 K s 104.3mAh / cm 2 DCR 50 It is 8.0mΩ, T max At 66.4℃, it still meets the combined requirements for capacity and thermal safety. When C 0.2 When it reaches 5300mAh, K v and K s The capacity was increased to 235.1 mAh / cm³. 3 and 106.3mAh / cm 2 DCR 50 Rising to 8.9mΩ, T max Reaching 68.0℃; when high capacity is combined with a small outer diameter and a high DCR, T max The temperature further increased to 69.5℃. This indicates that the upper limit of capacity load must be constrained by both DCR and temperature rise; otherwise, the heat accumulation inside the short-height casing will exceed the heat dissipation capacity of the side walls.

[0119] By comparing the data from Example 1, Comparative Example 4, and Comparative Example 5, it can be seen that in H1, D, C 0.2 K v and K s If all are the same, only DCR 50 The R value increases from 7.2mΩ to 9.4mΩ, even with the same capacity load. C40 It still dropped to 96.8%, R CE40 Dropped to 90.9%, T max The temperature rose to 68.8℃, indicating that excessive internal resistance can independently compromise rate-controlled thermal safety. Comparative Example 5 shows the DCR... 50 The resistance is 8.6 mΩ, close to the claim threshold, but due to the thermal response conditions, ΔT reaches 43.2℃, which also does not fall within the protection window. This result indicates that a reasonable capacity load does not necessarily guarantee rate thermal safety; resistive heating and actual thermal response must simultaneously meet the threshold. This demonstrates that the present invention is not a simple stacking of size, capacity, or DCR, but rather requires that capacity load, internal resistance, and temperature rise simultaneously satisfy a combined relationship.

[0120] Although embodiments of this implementation have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this implementation, the scope of which is defined by the claims and their equivalents.

Claims

1. A high-energy-density 21650 full-tab cylindrical lithium-ion battery, comprising a cylindrical shell, a core housed within the cylindrical shell, and an electrolyte, wherein the core is wound from a positive electrode sheet, a separator, and a negative electrode sheet, and the ends of the positive and negative electrode sheets are flattened to form a positive full-tab end face and a negative full-tab end face, respectively, characterized in that... Let H1 be the total height of the cylindrical shell, ranging from 63.5 to 66.5 mm, and D be the outer diameter of the cylindrical shell, ranging from 20.6 to 21.5 mm. The discharge capacity C of the cylindrical lithium-ion battery under 25°C and 0.2C discharge conditions is... 0.2 The cylindrical lithium-ion battery has a capacity of 4900~5200mAh and meets the following requirements: K v =C 0.2 / V cell 212~236 mAh / cm 3 , where V cell The external volume (cm) of the cylindrical shell is represented. 3 V cell =π×(D / 2)^2×H1 / 1000; K s =C 0.2 / A cell 96~106 mAh / cm 2 , where A cell The outer surface area (cm²) of the cylindrical shell is represented by the following value. 2 A cell =[π×D×H1+2π×(D / 2)^2] / 100.

2. The high energy density 21650 all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The high-energy-density 21650 full-tab cylindrical lithium-ion battery further includes a positive current collector and a negative current collector welded to both ends of the core along its axial direction. The positive current collector is welded to the end face of the positive full-tab, and the negative current collector is welded to the end face of the negative full-tab. The effective current-carrying cross-sectional area of ​​the positive current collector is 38~48 mm². 2 The equivalent contact area between the negative electrode current collector and the cylindrical shell is 25~32mm. 2 .

3. The high energy density 21650 all-tab cylindrical lithium-ion battery according to claim 2, characterized in that, The high-energy-density 21650 all-tab cylindrical lithium-ion battery meets one or more of the following conditions: a. Under conditions of 25℃, 40A constant current discharge to 2.5V or 80℃ safe cutoff, the highest temperature T on the large surface of the side wall of the cylindrical shell. max ≤67℃, and the rate discharge temperature rise ΔT≤42℃; b. Pulse DC internal resistance (DCR) at 25℃ and 50% SOC 50 ≤8.8mΩ.

4. The high energy density 21650 all-tab cylindrical lithium-ion battery according to any one of claims 1-3, characterized in that, The cylindrical lithium-ion battery maintains a capacity retention rate R at 40A based on a discharge capacity of 1A at 25°C. C40 >97.0%.

5. The high energy density 21650 all-tab cylindrical lithium-ion battery according to claim 4, characterized in that, The total height H1 of the cylindrical shell ranges from 64.7 to 65.5 mm, the outer diameter D ranges from 20.8 to 21.2 mm, and the ratio of H1 to D ranges from 3.06 to 3.

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6. The high energy density 21650 all-tab cylindrical lithium-ion battery according to claim 1, characterized in that, The external volume V of the cylindrical shell cell The range is 21.8~23.3cm 3 The outer surface area A of the cylindrical shell cell The range is 48.8~51.0 cm. 2 .

7. The high energy density 21650 all-tab cylindrical lithium-ion battery according to any one of claims 1-3, characterized in that, K v The range is 218~228 mAh / cm 3 K s 98~103 mAh / cm 2 .

8. The high energy density 21650 all-tab cylindrical lithium-ion battery according to claim 3, characterized in that, Under constant current discharge conditions of 25℃ and 40A, the cylindrical lithium-ion battery satisfies the following condition: temperature rise capacity load ratio 0 < ΔT / K. v ≤0.190℃·cm³ / mAh, and 0<T max / K s ≤0.68 ℃·cm² / mAh.

9. The high energy density 21650 all-tab cylindrical lithium-ion battery according to any one of claims 1-3, characterized in that, The pulsed DC internal resistance (DCR) of the high-energy-density 21650 omnipolar cylindrical lithium-ion battery at 25°C and 50% SOC. 50 The range is 6.5~8.2 mΩ.

10. The high energy density 21650 all-tab cylindrical lithium-ion battery according to any one of claims 1-3, characterized in that, The cylindrical lithium-ion battery maintains an energy retention rate R at 40A cycles based on a discharge capacity of 1A at 25°C. CE40 ≥91.2%.

11. An electrical appliance, characterized in that, Including the high energy density 21650 all-tab cylindrical lithium-ion battery as described in any one of claims 1-10.

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