Lithium-ion battery and lithium-ion battery system

Abstract

Lithium-ion battery comprising a casing, an electrical core and an electrolyte solution, wherein the electrical core and the electrolyte solution are arranged within the casing, wherein the electrical core comprises a cathode foil, an anode foil and a separator, the separator being arranged between the cathode foil and the anode foil, the cathode foil comprising a cathode collector and an active cathode substance layer, the active cathode substance layer being electrically connected to the cathode collector; wherein the anode foil comprises an anode collector and an active anode substance layer, the active anode substance layer being electrically connected to the anode collector; characterized in that the anode collector is provided on at least one surface with the active anode substance layer, wherein the thickness of the one-sided active anode substance layer of the anode foil is 50 µm to 95 µm; wherein the active anode substance layer comprises an active anode substance, the active anode substance comprising graphite; wherein Dv50 of the graphite is in a range of 10 µm to 30 µm, wherein the degree of graphitization of the graphite is greater than or equal to 90%; and that the cathode collector is provided with the active cathode substance layer on at least one surface, wherein the thickness of the one-sided active cathode substance layer of the cathode foil is 60 µm to 105 µm; wherein the active cathode substance layer comprises an active cathode substance, wherein the active cathode substance is a lithium-containing phosphate and a carbon layer located on the surface of the lithium-containing phosphate; where the capacity L of the lithium-ion battery is 500Ah < L ≤ 700Ah, and where the actual gas storage volume v of the lithium-ion battery is greater than 190 cm³ 3 is.

Description

[0001] The present application claims priority over the Chinese patent application under 202411346279.9 and entitled “Lithium-ion battery, charging method and lithium-ion battery system”, which was filed with the State Intellectual Property Office in China on September 26, 2024 and is incorporated in its entirety by reference as part of the present application. Technical field

[0002] The present application relates to the technical field of lithium batteries, in particular a lithium-ion battery and a lithium-ion battery system. State of the art

[0003] In recent years, with the ever-expanding use of batteries, they have been deployed in a wide variety of applications, such as energy storage systems for hydroelectric, thermal, wind, and solar power plants, as well as power tools, e-bikes, e-motorcycles, electric vehicles, military equipment, and aerospace. With the use of lithium batteries, battery capacity continues to increase, while the electrode foils become increasingly thicker. There is a demand for batteries with higher capacity and thicker electrode foils. However, with increasing battery capacity, especially with thicker electrode foils, there is a significantly greater amount of gas being produced inside the battery than before. It is becoming increasingly common for the battery's explosion vent to open. Once the explosion vent has opened, the battery can no longer be used.We assume that the battery's explosion vent valve should be opened in the event of abnormal use or extreme environmental conditions, and not during normal operation.

[0004] The problem of how to further improve the battery's capacity and multiplication power while simultaneously reducing the risk of the explosion protection valve being opened inappropriately and the battery having to be scrapped has become an urgent problem to be solved. Registration content

[0005] In view of the above problem, the purpose of the present application is to provide a large-capacity lithium-ion battery in which the explosion protection valve does not need to be opened during normal use.

[0006] To achieve the above purpose, the present application provides a lithium-ion battery comprising a housing, an electrical core, and an electrolyte solution, wherein the electrical core and the electrolyte solution are arranged within the housing, wherein the electrical core comprises a cathode foil, an anode foil, and a separator, the separator being arranged between the cathode foil and the anode foil, the cathode foil comprising a cathode collector and an active cathode substance layer, the active cathode substance layer being electrically connected to the cathode collector; wherein the anode foil comprises an anode collector and an active anode substance layer, the active anode substance layer being electrically connected to the anode collector; wherein the anode collector is provided on at least one surface with the active anode substance layer, wherein the thickness of the one-sided active anode substance layer is 50 µm to 95 µm; wherein the active anode substance layer comprises an active anode substance, wherein the active anode substance comprises graphite; wherein Dv50 of the graphite is in a range of 10 µm to 30 µm, wherein the degree of graphitization of the graphite is greater than or equal to 90%; wherein the cathode collector is provided on at least one surface with the active cathode substance layer, wherein the thickness of the one-sided active cathode substance layer is 60 µm to 105 µm; wherein the active cathode substance layer comprises an active cathode substance, wherein the active cathode substance is a lithium-containing phosphate and a carbon layer located on the surface of the lithium-containing phosphate; where the capacity L of the lithium-ion battery is 500Ah < L ≤ 700Ah, and where the actual gas storage volume v of the lithium-ion battery is greater than 190cm³ 3 is.

[0007] The present application also provides lithium-ion batteries with different capacities, in particular: The capacity L of the lithium-ion battery is 500Ah < L ≤ 600Ah , where the theoretical gas storage volume of the lithium-ion battery is V0, where V0=0.38cm 3 / Ah·L; or, The capacity L of the lithium-ion battery is 600Ah < L ≤ 700Ah, where the theoretical gas storage volume of the lithium-ion battery is V0, where V0=0.44cm 3 / Ah·L; where the actual gas storage volume v of the lithium-ion battery is larger than the theoretical gas storage volume of the lithium-ion battery V0.

[0008] Furthermore, preferably: The capacity L of the lithium-ion battery is 500Ah < L ≤ 600Ah , where the theoretical gas storage volume of the lithium-ion battery is V0, where V0=0.54cm 3 / Ah·L; or, The capacity L of the lithium-ion battery is 600Ah < L ≤ 700Ah, where the theoretical gas storage volume of the lithium-ion battery is V0, where V0=0.65cm 3 / Ah·L; where the actual gas storage volume v of the lithium-ion battery is larger than the theoretical gas storage volume of the lithium-ion battery V0.

[0009] To further increase the energy density, also: The capacity L of the lithium-ion battery is 500Ah < L ≤ 600Ah, where the theoretical maximum gas storage volume of the lithium-ion battery is V0max, where V0max=0.54 cm³ 3 / Ah·L; or, The capacity L of the lithium-ion battery is 600Ah < L ≤ 700Ah, where the theoretical maximum gas storage volume of the lithium-ion battery is V0max, where V0max=0.65 cm³3 / Ah·L;where the actual gas storage volume v of the lithium-ion battery is less than or equal to the theoretical gas storage volume of the lithium-ion battery V0max.

[0010] In some embodiments, at least a part of the surface of the graphite is coated with a carbon layer, wherein Dv90 of the graphite is less than or equal to 40 µm, wherein Dv10 of the graphite is greater than or equal to 3 µm, and wherein Dv99 of the graphite is less than or equal to 49 µm.

[0011] In some embodiments, the OI value of the graphite is in a range of 3 to 30, preferably the OI value of the graphite is in a range of 10 to 30, and more preferably the OI value of the graphite is in a range of 15 to 30.

[0012] In some embodiments, the degree of graphitization of the graphite is between 90% and 95%, preferably between 91% and 95%. In some embodiments, the areal density of the one-sided active substance layer of the anode foil is between 0.07 mg / mm². 2 up to 0.13 mg / mm 2 .

[0013] In some embodiments, the density of the one-sided active substance layer of the anode foil is between 1.3 g / cc and 1.7 g / cc.

[0014] In some embodiments, the areal density of the one-sided active substance layer of the cathode foil is between 0.16 mg / mm². 2 up to 0.26 mg / mm 2 .

[0015] In some embodiments, the density of the one-sided active substance layer of the cathode foil is between 2.3 g / cc and 2.7 g / cc.

[0016] In some embodiments, the separator comprises a base film and a coating, wherein the coating is bonded to the surface of the base film and is partially embedded within the base film, the porosity of the separator being between 30% and 50%. In some embodiments, the thickness of the carbon layer on the surface of the graphite is between 0.5 µm and 2 µm.

[0017] In some embodiments, the active anode substance layer further comprises a carbon tube, wherein the carbon tube comprises at least one oligo-walled carbon tube and one single-walled carbon tube.

[0018] In some embodiments, the active anode material layer further comprises silicon, wherein the mass content of the silicon in the active anode material layer is between 1% and 8%.

[0019] In some embodiments, the silicon is distributed in the thickness direction of the active anode material layer on a side facing the anode collector in the active anode material layer.

[0020] In some embodiments, the lithium-containing phosphate comprises lithium iron phosphate, wherein the lithium iron phosphate is doped with a metal element, the metal element being selected from at least one of the elements titanium or vanadium.

[0021] In some embodiments, the mass fraction of the doped metal element in the active cathode substance is no more than 0.4%.

[0022] In some embodiments, the doped metal element comprises titanium, wherein the mass fraction of titanium in the active cathode substance is 0.2% to 0.4%.

[0023] In some embodiments, the doped metal element comprises titanium and vanadium, wherein the mass fraction of titanium in the active cathode substance is 0.1% to 0.2%, and wherein the mass fraction of vanadium in the active cathode substance is 0.01% to 0.05%.

[0024] In some embodiments, the active cathode substance layer comprises a carbon tube, wherein the carbon tube comprises at least one of an oligo-walled carbon tube and a single-walled carbon tube.

[0025] In some embodiments, the electrolyte solution comprises a lithium salt and a solvent, wherein the molar volume content of the lithium salt is 0.8 mol / L to 1.5 mol / L, and the lithium salt comprises lithium hexafluorophosphate.

[0026] In some embodiments, the lithium salt further comprises lithium bis(fluorosulfonyl)imide. In some embodiments, the molar volume content of lithium hexafluorophosphate is higher than the molar volume content of lithium bis(fluorosulfonyl)imide.

[0027] In some embodiments, the mass fraction of lithium bis(fluorosulfonyl)imide in the electrolyte solution is between 3% and 9%.

[0028] In some embodiments, the solvent comprises EC, DMC, EMC, DEC; wherein the content of EC is between 30% and 40%, wherein the sum of the masses of DMC and EMC is greater than the mass of EC; wherein the content of EC is equal to the mass of EC / (the difference between the mass of the electrolyte solution and the mass of the lithium salt).

[0029] In some embodiments, the total content of EMC and DMC is in the range of 50% to 60%; where the total content of EMC and DMC is equal to the total mass of EMC and DMC / (the difference between the mass of the electrolyte solution and the mass of the lithium salt).

[0030] In some embodiments, the DMC content is in the range of 10% to 15%; where the DMC content is equal to the mass of DMC / (the difference between the mass of the electrolyte solution and the mass of the lithium salt).

[0031] In some embodiments, the electrolyte solution further comprises a carboxylic acid ester, wherein the content of the carboxylic acid ester is not more than 10%; wherein the content of the carboxylic acid ester is equal to the mass of the carboxylic acid ester / (the difference between the mass of the electrolyte solution and the mass of the lithium salt).

[0032] In some embodiments, the anode foil has a square structure, wherein the width of the anode foil is between 100 mm and 150 mm, wherein the porosity of the separator is in the range of 30% to 50%, wherein preferably the length-to-width ratio of the electrical core is between 6 and 8.

[0033] In some embodiments, the anode foil has a square structure, wherein the width of the anode foil is between 200 mm and 250 mm, wherein the porosity of the separator is in the range of 35% to 50%, wherein preferably the length-to-width ratio of the electrical core is between 2.8 and 4.

[0034] In some embodiments, the anode foil further comprises an anode tab, wherein the anode tab is electrically connected to the anode collector, and the cathode foil further comprises a cathode tab, wherein the cathode tab is electrically connected to the cathode collector; wherein the housing comprises a cathode column, an anode column and an explosion protection valve, wherein the cathode column is electrically connected to the cathode tab, while the anode column is electrically connected to the anode tab, wherein the explosion protection valve is arranged at a first end of the housing, wherein at least one of the cathode column and the anode column is arranged at the first end of the housing, wherein the opening air pressure of the explosion protection valve is 0.55 MPa to 0.65 MPa, wherein the ratio of the area of ​​the explosion protection valve to the capacity of the lithium-ion battery is in the range of 0.5 mm² 2 / Ah up to 1.5 mm 2 Ah, it lies.

[0035] In some embodiments, the cathode column is arranged at the first end of the housing, and the cathode tab is arranged on a short edge of the cathode collector; wherein a first upper exhaust channel is formed between the upper end of the cathode tab and the housing, wherein, along the airflow direction of the first upper exhaust channel, the projection area of ​​the explosion protection valve overlaps at least partially with the projection area of ​​the first upper exhaust channel.

[0036] In some embodiments, along the airflow direction of the first upper exhaust duct, the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the first upper exhaust duct is more than 80%; wherein the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the first upper exhaust duct is the ratio of the area of ​​an overlap area between the projection area of ​​the explosion protection valve and the projection area of ​​the first upper exhaust duct to the area of ​​the projection area of ​​the first upper exhaust duct.

[0037] In some embodiments, the cathode tabs are distributed asymmetrically on the short edge of the cathode collector.

[0038] In some embodiments, along a width direction of the electrical core, the vertical distance from an upper end of the cathode tab to the upper end of the cathode foil is a first distance, wherein the vertical distance from a lower end of the cathode tab to the lower end of the cathode foil is a second distance, the first distance being greater than the second distance.

[0039] In some embodiments, the anode column is arranged at the first end of the housing, and the anode tab is arranged on a short edge of the anode collector; wherein a second upper exhaust channel is formed between the upper end of the anode tab and the housing, wherein, along the airflow direction of the second upper exhaust channel, the projection area of ​​the explosion protection valve overlaps at least partially with the projection area of ​​the second upper exhaust channel.

[0040] In some embodiments, along the airflow direction of the second upper exhaust duct, the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the second upper exhaust duct is more than 80%; wherein the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the second upper exhaust duct is the ratio of the area of ​​an overlap area between the projection area of ​​the explosion protection valve and the projection area of ​​the second upper exhaust duct to the area of ​​the projection area of ​​the second upper exhaust duct.

[0041] In some embodiments, the ratio of the width of the anode tab to the width of the short edge of the anode collector is in the range of 0.5 to 0.8, optionally in the range of 0.6 to 0.8.

[0042] In some embodiments, the anode tabs are distributed asymmetrically on the short edge of the anode collector.

[0043] In some embodiments, along a width direction of the electrical core, the vertical distance from an upper end of the anode tab to the upper end of the anode foil is a third distance, wherein the vertical distance from a lower end of the anode tab to the lower end of the anode foil is a fourth distance, the third distance being greater than the fourth distance.

[0044] In some embodiments, the difference between Dv50 and Dv10 of the graphite is less than or equal to 10 µm, with the difference between Dv90 and Dv50 of the graphite being less than or equal to 15 µm.

[0045] In some embodiments, the cathode collector is an aluminum foil, wherein the thickness of the one-sided active substance layer of the cathode foil is less than or equal to 95 µm, wherein the thickness of the cathode collector is D1, where the value of D1 is in the range of 11 µm to 13.5 µm.

[0046] In some embodiments, the thickness of the one-sided active substance layer of the cathode foil is greater than 95 µm, where the thickness of the cathode collector is D2, with the value of D2 being in the range of 13.5 µm to 16 µm.

[0047] In some embodiments, the active anode substance layer further comprises silicon; wherein the thickness of the one-sided active substance layer of the anode foil is in the range of 50 µm to 70 µm, wherein the mass content of the silicon in the active anode substance layer is in the range of 1% to 10%.

[0048] In some embodiments, the active anode substance layer further comprises silicon; wherein the thickness of the one-sided active substance layer of the anode foil is in the range of 70 µm to 80 µm, wherein the mass content of the silicon in the active anode substance layer is in the range of 1% to 8%.

[0049] In some embodiments, the active anode substance layer further comprises silicon; wherein the thickness of the one-sided active substance layer of the anode foil is in the range of 80 µm to 95 µm, wherein the mass content of the silicon in the active anode substance layer is in the range of 1% to 5%.

[0050] In some embodiments, the electrolyte solution further comprises a carboxylic acid ester, wherein the content of the carboxylic acid ester is in the range of 5% to 10%, and wherein the mass fraction of the lithium bis(fluorosulfonyl)imide in the electrolyte solution is between 2% and 7%.

[0051] In some embodiments, the active anode substance comprises graphite and primary particles formed by the carbon layer on the surface of the graphite, wherein Dv50 of the primary particles is in the range of 10 µm to 20 µm.

[0052] In some embodiments, the active anode substance comprises secondary particles, wherein the secondary particles comprise agglomerates of the primary particles, with Dv50 of the secondary particles being in the range of 10 µm to 30 µm.

[0053] In some embodiments, the surface of the agglomerates is coated with the carbon layer.

[0054] A charging method is disclosed for charging a lithium-ion battery, wherein the charging method comprises a first charging stage and a second charging stage, wherein the voltage of the first charging stage is lower than the voltage of the second charging stage, wherein the voltage of the first charging stage increases with increasing charging time, while the voltage of the second charging stage remains unchanged, and wherein the first charging stage comprises the following charging operations: Charging the lithium-ion battery within a first period with a first current; charging the lithium-ion battery within a second period with a second current; Charging the lithium-ion battery within a third period with a third current; charging the lithium-ion battery within a fourth period with a fourth current; wherein the first current is greater than the second current, wherein the first period is longer than the second period, wherein the third current is not greater than the first current, wherein the third period is longer than the second period, wherein the fourth current is less than the third current, wherein the fourth period is shorter than the third period.

[0055] The second current is the same as the fourth current.

[0056] The present application further provides a lithium-ion battery system, wherein the system comprises a management module and a lithium-ion battery, wherein the management module comprises a charging program for the lithium-ion battery, and wherein the charging program implements the charging method. Description of the drawings Fig. Figure 1 is a schematic representation of the structure of a cathode foil of the present application. Fig. Figure 2 is a schematic representation of the structure of an anode foil of the present application. Fig. Figure 3 is a schematic representation of the structure of a lithium-ion battery of the present application. Fig. Figure 4 is a schematic representation of a gas evolution process of the lithium-ion battery of the present application. Fig. Figure 5 is a schematic representation of the structure of another anode foil of the present application. Fig. Figure 6 is a schematic representation of the structure of another cathode foil of the present application. Fig. Figure 7 is a schematic representation of the structure of another cathode foil of the present application. Fig. Figure 8 is a schematic representation of the structure of another anode foil of the present application. Fig. Figure 9 is a schematic representation of the structure of another lithium-ion battery of the present application. Fig. Figure 10 is a schematic representation of another gas evolution process of the lithium-ion battery of the present application. Reference symbol list:

[0057] 10 Cathode foil; 11 Cathode tab; 20 Anode foil; 21 Anode tab; 30 Electrical core; 40 Housing; 41 Cathode column; 42 Anode column; 43 Explosion protection valve; 50 Indicating arrow for airflow direction; 51 First upper exhaust duct; h1 First spacing; h2 Second spacing; h3 Third spacing; h4 Fourth spacing; Ld Longitudinal direction; Hd Vertical direction. Detailed description of the embodiments

[0058] The following section describes in detail embodiments of a lithium-ion battery and a lithium-ion battery system of the present application with reference to the accompanying drawings. However, there will be instances where an unnecessarily detailed description is omitted. For example, detailed descriptions of things that are already well known and repeated descriptions of the same structure are omitted. This is to avoid making the following description unnecessarily long and to facilitate understanding by the person skilled in the art. Furthermore, the accompanying drawings and the following description serve to ensure the complete understanding of the present application by the person skilled in the art and are not intended to limit the subject matter specified in the claims.

[0059] The "range" disclosed here is defined in terms of a lower bound and an upper bound, with a particular range being defined by selecting a lower bound and an upper bound that establish the limits of that range. Ranges defined in this way can include or exclude end values ​​and can be combined in any way; that is, any lower bound can be combined with any upper bound to form a range. For example, if a range of 60-120 and 80-110 is specified for a particular parameter, a range of 60-110 and 80-120 is also to be expected. Furthermore, if the minimum values ​​1 and 2 and the maximum values ​​3, 4, and 5 are specified, the following ranges can be expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5.Unless otherwise specified, the range "ab" denotes any combination of real numbers between a and b, where both a and b are real numbers. For example, the range "0-5" means that all real numbers between 0 and 5 are listed here, and 0-5 is simply a shorthand representation of the combination of these values. Furthermore, stating that a parameter is an integer ≥ 2 is equivalent to stating that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and so on.

[0060] Unless expressly stated otherwise, all embodiments and optional embodiments of the present application may be combined to form new technical solutions.

[0061] Unless expressly stated otherwise, all technical features of the present application, as well as optional technical features, may be combined to form a new technical solution.

[0062] Unless otherwise stated, references to "including" and "comprehensive" in this application denote an open or closed formulation. For example, the terms "including" and "comprehensive" may mean that other, unlisted components may also be included or contained, or that only the listed components may be included or contained.

[0063] Unless otherwise stated, the term "or" in this application is comprehensive. For example, the phrase "A or B" means "A, B, or both A and B." More precisely, the condition "A or B" is satisfied by any one of the following: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist). The lithium-ion battery of the present application comprises a housing, an electrical core, and an electrolyte solution, wherein the electrical core and the electrolyte solution are arranged within the housing, the housing being sealed, and the electrical core comprising a cathode foil, an anode foil, and a separator, in particular as follows: Anode foil:

[0064] The anode foil comprises an anode collector and an active anode substance layer. At least one surface of the anode collector is coated with the active anode substance layer, which is electrically connected to the anode collector.

[0065] The active anode material layer comprises an active anode material, wherein the active anode material comprises graphite. The graphite can be natural graphite or synthetic graphite, with synthetic graphite being preferred.

[0066] Graphite with different particle sizes exhibits varying specific surface areas and gas evolution. The smaller the graphite particle size, the more easily lithium ions can be embedded between and released from the graphite layers. However, smaller graphite particle sizes increase the specific surface area, leading to greater SEI formation and thus higher gas evolution. Increased SEI formation not only reduces the initial efficiency of lithium-ion batteries but also causes the SEI to be continuously consumed and regenerated during the battery's charge and discharge cycles. This results in increased gas evolution throughout the battery's lifespan. Conversely, the graphite particle size must not be too large.Excessively large graphite particles can lead to the formation of lithium dendrites on the surface of the graphite if the lithium ions cannot penetrate the graphite layers quickly enough, potentially resulting in gas evolution through reaction with the electrolyte solution. This problem of lithium dendrite formation and gas evolution becomes particularly pronounced at high charging rates (charge rates above 1C). For the high-capacity electric core and thick electrode foil of the present application (where "high-capacity electric core and thick electrode foil" refers to a lithium-ion battery with a capacity of at least 200 Ah, where the density of the single-sided active anode material layer is between 1.3 g / cm³), this is a significant concern. 3 and 1.7 g / cm³ 3(The density is measured within the first 100 charge and discharge cycles of the lithium-ion battery. During the manufacture of lithium-ion batteries, the electrode foils are typically subjected to roller pressing to increase the density. However, the density of the electrode foils often decreases during the first cycle phase of the finished lithium-ion battery. To more accurately reflect the density of the finished lithium-ion battery, the applicant therefore selected the density of the single-sided active anode layer from lithium-ion batteries with a low number of charge and discharge cycles.) Furthermore, the areal density of the single-sided anode layer is between 0.07 mg / mm². 2 and 0.13 mg / mm 2(The areal density is measured within the first 100 charge and discharge cycles of the lithium-ion battery.) The graphite particle size, calculated as Dv50, is specified as 10 µm to 30 µm. Simultaneously, the applicant has implemented further design measures to prevent excessive formation of large-particle graphite within the anode foil. This is because, in the anode foil, if the graphite particle size exceeds 50 µm, the lithium ions accumulated in the area corresponding to the large-particle graphite may penetrate the graphite layers too late. This leads to partial deposition of lithium ions on the graphite surface, forming lithium dendrites that can even penetrate the SEI film, resulting in further consumption of the electrolyte solution to form the SEI and gas evolution.As the lithium dendrites continue to grow, not only does the local temperature at that point increase, but the dendrites can even puncture the separator and cause a short circuit inside the lithium-ion battery, leading to severe gas evolution or even an explosion and other potential hazards. Furthermore, the problem of lithium dendrites at the contact point between the anode foil and the edge of the cathode foil is even more serious, due to the large particle size of the graphite.The more concentrated the graphite with the large particle size, the easier it is to form lithium dendrites at the concentrated area. Therefore, it is necessary to remove as much of the graphite with the large particle size as possible during the production of the anode foil and to ensure that the amount of graphite with the large particle size is within a controllable range. In particular, it is possible to control that the value of Dv90 of the graphite is not greater than 40 µm, and further to control that the value of Dv99 of the graphite is not greater than 49 µm.

[0067] On the other hand, in the case of the high-capacitance electrical core and the thick electrode foils of the present application, the particle size of the graphite must be controlled not only in the area of ​​Dv50, but also in such a way that there is not too much graphite with the small particle size in the electrode foils, in order to reduce the problem of continuous gas evolution caused by the specific surface area factor of the graphite with the small particle size, and in particular to ensure that the value of Dv10 is not less than 3 µm.

[0068] Furthermore, the inventors inventively set the difference between Dv50 and Dv10 of graphite to ≤10 µm and the difference between Dv90 and Dv50 of graphite to ≤15 µm. By setting these two difference values, the particle size distribution of the graphite becomes more concentrated, resulting in a more uniform current density throughout the anode foil. The more uniform the current density distribution in the anode foil, the lower the probability of lithium dendrites forming, and the destructive effect of SEI on the graphite surface is reduced, further minimizing gas evolution. On the other hand, to improve the packing density of the electrode foil, the packing density is often intentionally increased by mixing particles of larger and smaller sizes during the manufacturing process, thereby further increasing the volumetric capacitance of the electrical core.In electrical cores with high volumetric capacitance requirements, a design in which the difference between Dv50 and Dv10 is less than or equal to 10 µm and the difference between Dv90 and Dv50 is less than or equal to 15 µm may not be used.

[0069] Because graphite has a layered structure, lithium ions in the electrolyte solution are more likely to penetrate between the graphite layers during the cycles of a lithium-ion battery to complete lithium embedding. They are less likely to be embedded in the direction perpendicular to the graphite layers, which corresponds to the OI value of the graphite (degree of orientation, C004 / C110). The higher the OI value, the easier it is for the lithium to be embedded. When graphite is used as the active anode material, inventors design the OI value of the graphite (which can also be graphite after carbon coating) to be in the range of 3 to 30. If the OI value is less than 3, lithium embedding in the graphite will be difficult, resulting in a large number of lithium dendrites and significant gas evolution in the high-capacity electrical core of 200 Ah or more.Furthermore, lithium-ion batteries with a capacity of more than 200Ah are generally used as lithium-ion batteries for energy storage; they do not need to be charged and discharged at a high rate (although in some embodiments or application scenarios, high-rate charging and discharging is required for lithium-ion batteries used for energy storage), so for cost reasons, it is not necessary for the OI value to be greater than 30; otherwise, the cost efficiency would not be high.

[0070] The degree of graphitization of graphite produced by different processes varies, and the inventor expects to use graphite with a higher and better degree of graphitization. The higher the degree of graphitization, the less easily the graphite layers detach during the cycling process, the more stable the SEI (State Electrical Index), and the lower the gas evolution during long cycles. However, due to the limitations of the existing manufacturing process for synthetic graphite and cost-efficiency considerations, the degree of graphitization cannot be unlimited. According to the inventors' design of the present application, in the high-capacity lithium-ion battery and the thick electrode foils of the present application, the degree of graphitization (including the graphite after the carbon coating in the present application) is intended to be greater than or equal to 90%.To meet the requirements of a high-capacity lithium-ion battery of 400 Ah or more, the inventors prefer that the graphite's degree of graphitization be between 91% and 95%. If the degree of graphitization is less than 91%, the high-capacity lithium-ion battery of 400 Ah or more will exhibit greater gas evolution during long-cycle operation. However, if the degree of graphitization is greater than 95%, the inventor believes that, given the current price of graphite, the cost-effectiveness of using graphite with a degree of graphitization above 95% is no longer advantageous.

[0071] To further reduce gas evolution, the inventors of the present application coated the graphite surface with carbon. After the graphite was coated with amorphous carbon, the numerous embedding sites for lithium ions in the amorphous carbon reduce the impact of lithium ions between the graphite layers during fast charging and mitigate the problem of graphite layer delamination, thus reducing gas evolution.On the other hand, the carbon coating can reduce the capacity of the anode foil, so the amount of carbon coating should not be too large; at the same time, the amount of carbon coating should not be too small, as too small an amount is not conducive to the formation of a uniform carbon coating; the inventor of the present application controls the thickness of the carbon coating of the graphite to a value between 0.5 µm and 2 µm.To verify the thickness and uniformity of the carbon coating, the inventor of the present application discharged and disassembled the lithium-ion battery after cycling. Samples were taken from the disassembled anode foil after scraping off the powder to measure dTEM. Five graphite particles were randomly selected within the TEM field of view, and five points were evenly spaced on the circumferential surface of each graphite particle to measure the thickness of the carbon coating. An average of the 25 resulting measurements was then taken to determine the thickness of the carbon coating. Since the thickness of the carbon coating is very small and has only a minor influence on the graphite particle size, the present application investigates the effect of the carbon coating on the graphite particle size (e.g.,Dv50) is ignored, as is the effect of the carbon coating on the degree of graphitization and the OI value. To facilitate the analysis of the influence of the above-mentioned graphite particle size from the end of the finished lithium-ion battery, factors such as the presence of a conductive agent, etc., in the active anode substance layer will indeed influence the range of graphite particle size during testing and analysis of the finished lithium-ion battery, but due to factors such as the low content, they are also ignored in the present application.After ignoring such minor factors, the present application considers the range of particle size of the graphite obtained from the test of the finished lithium-ion battery to be the same as the range of particle size of the initial graphite, and considers the degree of graphitization and the OI value of the graphite obtained from the test of the finished lithium-ion battery to be the same as the range of degree of graphitization and the OI value of the initial graphite.

[0072] Graphite can consist of primary particles or primary particles formed after the carbon coating. The active anode material comprises graphite and primary particles formed by the carbon layer on the graphite surface, with the Dv50 of the primary particles ranging from 10 µm to 20 µm. Graphite can also be an agglomerate formed by the agglomeration of primary particles, i.e., secondary particles. The Dv50 of the secondary particles ranges from 10 µm to 30 µm. However, such agglomerates have an increased specific surface area due to the presence of primary particles.To reduce gas evolution, the preferred structure for such secondary particles is: a carbon layer is coated on the surface of the primary particles, and the carbon-coated primary particles are agglomerated to form secondary particles; and further preferably, a carbon layer is coated on the surface of the secondary particles formed by the agglomerates; the composition of the carbon layer on the surface of the primary particles may differ from or be the same as the composition of the carbon layer coated on the surface of the secondary particles.The manufacturing process for such carbon-coated secondary particles is disclosed: Dispersing the primary particles in a solution containing a monomer of an organic carbon source, and carrying out a hydrothermal polymerization reaction, after which a coating layer containing a polymer of an organic carbon source is formed on the surface of the primary particles, and subsequent carbonization to obtain the carbon-coated primary particles; Subsequent dispersion of the carbon-coated primary particles in a liquid containing a precursor of the organic carbon source, and spray drying and subsequent carbonization.Such carbon-coated secondary particles can better meet the gas evolution requirements of the high-capacity electric core and the thick electrode foils of the present application, especially for the high-capacity electric core of 400Ah or more.

[0073] The anode foil comprises not only the active anode material (where the active anode material of the present application comprises graphite, and the surface of the graphite may be coated with carbon), but also a binder and a conductive agent. The technical solution of the present application is used for a single-sided active anode material layer with a density between 1.3 g / cc and 1.7 g / cc. (The density is measured within the first 100 charge and discharge cycles of the lithium-ion battery.) In the manufacture of lithium-ion batteries, the electrode foils are typically subjected to roller pressing to increase the density. However, the density of the electrode foils often decreases during the first cycle phase of the finished lithium-ion battery.To more accurately reflect the density of the finished lithium-ion battery, the applicant therefore selected the density of the single-sided active anode layer from the electrical cores with a low number of charge and discharge cycles. Furthermore, the areal density of the single-sided anode layer is between 0.07 mg / mm². 2 and 0.13 mg / mm 2(The areal density is measured within the first 100 charge and discharge cycles of the lithium-ion battery). The thickness of the single-sided active anode substance layer is between 50 µm and 95 µm, the thickness of the anode collector is 5 µm, and the thickness of the anode foil is 105 µm to 195 µm, corresponding to the thickness of the anode collector when both surfaces of the anode collector are coated with the active anode substance layer (the thickness of the active anode substance layer and the thickness of the anode foil are measured within the first 100 charge and discharge cycles of the lithium-ion battery).Due to the considerable thickness of the anode foil used in the technical solution of the present application to maintain good electrical contact at all positions in the active anode layer, it is preferred in the present application that the conductive element in the active anode layer comprises a carbon tube, and it is preferred that the single-walled carbon tube and / or the oligo-walled carbon tube is used. The single-walled carbon tube used in the present application has a length of 1 µm to 50 µm and a section of graphene foil with a diameter of 0.75 nm to 10 nm, and more preferably 1 nm to 3 nm. The oligo-walled carbon tube used in the present application has a section of 2 to 5 layers of graphene foil and a diameter in the range of 1 nm to 15 nm, and more preferably 2 nm to 5 nm.Compared to other conventional conductive materials such as carbon black, single-walled or oligo-corrugated carbon tubes exhibit better conductivity. However, in thick electrode foils, the large surface area of ​​the foil and the expansion and contraction of the graphite during the cycling process, especially after silicon doping, further increase the thickness difference. This thick electrode foil is likely to make it difficult for the active substance in the upper part of the foil to retain electrons during the cycling process. It could even lead to a layering effect, making it even harder for the upper layer of the active substance to retain electrons, which poses a significant problem.The single-walled carbon tube or the oligo-corrugated carbon tube has a larger length-to-thickness ratio than the carbon black, which enables it to fix the thick electrode foil, improve the ability of the upper active substance to retain electrons, and prevent the occurrence of the layering phenomenon.

[0074] The active anode material of the anode foil of the present application can contain silicon in addition to graphite. The silicon is used to improve the capacity of the overall lithium-ion battery. However, the problem of silicon's cyclic expansion makes it impossible to have too much silicon in the thick electrode foil, and especially in the high-capacity electrical cores and the thick electrode foils of the present application, the expansion problem is more likely to lead to layering of the thick electrode foil, causing the problem of interrupting the conduction path for the active material. On the other hand, the continuous breaking up and regeneration of the SEI due to silicon expansion during charge and discharge cycles is accompanied by persistent gas evolution, and the larger the capacity of the lithium-ion battery, the more pronounced this gas evolution becomes.The more severe the problem of gas evolution due to silicon expansion, the greater the risk. Therefore, in the present application, two factors must be considered regarding the range of silicon mass fraction in the active anode material layer, and the intersection of these two factors must be determined. The first factor is the influence of the lithium-ion battery capacity on the silicon content, as follows: If the lithium-ion battery capacity is 200 Ah ≤ L ≤ 500 Ah, and more preferably 300 Ah < L ≤ 500 Ah, the silicon mass fraction in the active anode material layer is in the range of 1% to 10%. If the lithium-ion battery capacity L is 500 Ah... <L≤700Ah beträgt, liegt der Massengehalt an Silizium in der aktiven Anodensubstanzschicht im Bereich von 1% bis 8%; Wenn die Kapazität der Lithium-Ionen-Batterie 700Ah<L≤1100Ah beträgt,The mass fraction of silicon in the active anode layer is in the range of 1% to 5%; The second aspect of the factors is the influence of the thickness of the one-sided active layer of the anode foil on the silicon content, as follows: If the thickness of the one-sided active layer of the anode foil is 50 µm to 70 µm, the mass fraction of silicon in the active anode layer is in the range of 1% to 10%; If the thickness of the one-sided active layer of the anode foil is 70 µm to 80 µm, the mass fraction of silicon in the active anode layer is preferably in the range of 1% to 8%; If the thickness of the one-sided active layer of the anode foil is 80 µm to 95 µm, the mass fraction of silicon in the active anode layer is preferably in the range of 1% to 5%.

[0075] In the thickness direction of the active anode material layer, the silicon is mainly or completely distributed in a lower part of the active anode material layer, i.e., on a side facing the anode collector. Furthermore, preferably the silicon content on the side of the active anode material layer facing the anode collector is higher than the silicon content on the side of the active anode material layer facing away from the anode collector, and preferably the side of the active anode material layer facing away from the anode collector contains no silicon.

[0076] The lower part of the active anode substance layer described here refers to a part of the active anode substance layer facing the anode collector in the thickness direction of the active anode substance layer; accordingly, the active anode substance layer comprises an upper part, which refers to a part of the active anode substance layer facing away from the anode collector.The surface facing away from the anode collector in the active anode material layer described in the present application refers to a region along the thickness direction of the active anode material layer from a surface of the active anode material layer facing away from the anode collector to a depth of 20 µm. The surface facing the anode collector in the active anode material layer described in the present application refers to a region along the thickness direction of the active anode material layer from a surface of the active anode material layer facing the anode collector to a depth of 20 µm. It is possible to cut through the active anode material layer, examine the cut surface with a scanning electron microscope (SEM), and determine the silicon elemental content with an X-ray spectrometer (EDS).

[0077] In the thickness direction of the active anode layer, the silicon is distributed mainly or entirely in the lower part of the active anode layer, so that during the silicon expansion and contraction process, the upper part of the active anode layer can be used to hold down the lower part of the active anode layer, thereby mitigating the adverse effects caused by silicon expansion. Furthermore, in the present application, the silicon in the active anode layer refers to the silicon element, which may, for example, comprise one or more silicon monomers, silicon oxides, silicon nitrides, or salts containing the silicon element (such as silicates).

[0078] In particular, the structure of the silicon-containing active anode substance layer in the present application is structured as follows: One way: Silicon is distributed in both the upper and lower parts of the active anode substance layer, with the silicon content in the upper part of the active anode substance layer being lower than the content in the lower part; this can be achieved in particular by measuring the silicon content on the lower surface facing the active anode substance layer (the surface facing the collector) and by measuring the silicon content on the upper surface facing the active anode substance layer.

[0079] A second way: Silicon is only distributed in the lower part of the active anode substance layer, and the upper part of the active anode substance layer contains no silicon; in particular, the thickness range of 20µm from the upper surface of the active anode substance layer contains no silicon, since the upper active anode substance layer can no longer play a role in holding down the active anode substance layer after exceeding 20µm. Structure of the anode foil:

[0080] The anode foil of the present application comprises an anode collector and an active anode substance layer, wherein the anode collector can be a copper foil, a carbon fiber collector or a porous collector, and the active anode substance layer is combined with the anode collector such that the active anode substance layer receives electrons through the anode collector in the cycle process of the lithium-ion battery.

[0081] The anode foil further comprises an anode tab, wherein the anode tab is electrically connected to the anode collector and the anode tab is connected to the anode collector in various ways, e.g. by welding the anode tab to the anode collector or by forming a one-piece structure with the anode collector (e.g., where the anode collector is a copper foil and the anode tab is cut and shaped through the anode collector).

[0082] The anode collector can have a variety of structures. For example, in the first structure, the anode collector can be a rectangle with a long edge and a short edge. The long edge of the anode collector is the length of the rectangular structure, the short edge is the width of the rectangle, the active anode substance layer is located in at least part of an area of ​​the upper and lower surfaces of the anode collector, and the anode tab is located on the short edge of the anode collector. In the second structure, the anode collector is also a rectangular structure comprising a long edge and a short edge. The anode tab is located on the long edge of the anode collector, and multiple anode tabs are located on each long edge. The long edge of the anode collector in the second structure is longer than the long edge of the anode collector in the first structure, making it necessary to...that a large number of anode tabs are arranged on the anode collector of the second structure, which helps to reduce heat generation at the tab locations of the electrical core with the thick electrode foils. In the first structure, the anode tabs can be arranged on one or more short edges of the anode collector. Since the long edge of the anode collector is relatively long, in particular the anode collector has a length-to-width ratio of more than 6, and the supply of electrons within the entire anode foil is related to the width of the anode tab, if the width of the anode tabs is insufficient, this leads to strong heating at the locations of the anode tabs, so that the ratio of the width of the anode tabs to the width of the short edge of the anode collector should not be less than 0.5 should be; With further optimization, the ratio of the width of the anode tabs to the width of the short edge of the anode collector is in the range of 0.5 to 0.8 and cannot exceed 0.8, since after exceeding 0.8 the anode collector is very close to the casing and, if the casing is a conductor, a slight impact could easily cause an electrical connection between the anode collector and the casing; Furthermore, the ratio of the width of the anode tab to the width of the short edge of the anode collector is in the range of 0.6 to 0.8, since at a charging rate of not less than 3C the effect of heat generation at the location of the anode tab is further increased. Therefore, the ratio of the width of the anode tab to the width of the short edge of the anode collector can be set at not less than 0.6.to reduce the influence of heat generation at the locations of the anode tabs (the cathode tab is arranged in the same way as the anode tab).

[0083] Manufacturing process of the anode foil: The manufacturing process of the anode foil includes the following steps: Step 1: Mixing the substances such as the active anode substance, the conductive agent, the binder, etc., to form the active anode substance layer. This mixing process involves two types of procedures.Method 1: Mixing the active anode substance, the conductive agent, the binder, the solvent for the binder, and other substances to form a liquid slurry; applying the slurry to the surface of the copper foil as an anode collector or to the surface of the carbon fiber as an anode collector and between the carbon fibers; and obtaining an anode foil precursor for the manufacture of an electrical core by drying, roller pressing, and other processes after application; Method 2: Mixing the active anode substance, the conductive agent, the binder, and other substances (which may contain a small amount of binder and solvent) to form a non-flowing solid or semi-solid mixture; and hot-pressing the same onto the anode collector to form the anode foil precursor. Step 2: Cut off the anode foil precursor to obtain the anode foil to be used.

[0084] On the anode foil precursor formed in Process 1, a thin zone is located on the active anode substance layer on the surface of the anode collector, and this thin zone is formed in various ways. For example, in Process 1 above, the foil containing the anode collector is coated by a plurality of coating nozzles, and the coating quantity from some of the nozzles during the coating process is smaller than that from the other nozzles. Then, the coating zone formed by the nozzle with the smaller coating quantity, and subsequently formed during the drying process, is the thin zone.The distance between the multiple coating nozzles can also be adjusted so that the coating fluid formed by the multiple coating nozzles does not touch each other or only partially touches the foil of the anode collector, and a thin zone is formed at the edge of the coating fluid due to the small thickness of the edge of the coating fluid during the coating and drying process;

[0085] In method 2, the cutting is carried out along the thin zone, whereby the edge of the long edge of the obtained anode foil encloses the thin zone; that is, the edge thickness of the long edge of the anode foil is less than the thickness of the middle part of the anode foil.

[0086] The above manufacturing process increases costs, and therefore the thin zone cannot be formed for cost reasons, so that the edge thickness of the long edge of the anode foil obtained after cutting is essentially equal to the thickness of the middle part of the anode foil. Cathode foil:

[0087] The cathode foil comprises a cathode collector and an active cathode substance layer. At least one surface of the cathode collector is coated with the active cathode substance layer, which is electrically connected to the cathode collector.

[0088] The active cathode layer comprises an active cathode compound, which can be selected from a lithium-containing phosphate such as lithium iron phosphate or lithium manganese iron phosphate, or a ternary cathode material such as lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide, or an elemental doping of the first two. Due to its material properties, the ternary cathode material tends to evolve gas during charge and discharge cycles, especially if the nickel content in the ternary cathode material is high. This results in abnormally large gas evolution during normal cycling under the high-capacity electrical core, and it is even possible for the gas evolution during normal cycling to open the explosion protection valve, leading to the failure of the lithium-ion battery.Therefore, the preferred cathode material in the technical solution of the present application is lithium phosphate. However, lithium phosphate has poor electrical conductivity, and it is necessary to coat the surface of the lithium phosphate with a carbon layer. At the same time, compared to the ternary cathode material, the capacitance of lithium phosphate is low. Thus, the present application proposes doping the lithium phosphate with metallic elements to improve its capacitance. In particular, doping with one or more titanium or vanadium elements can increase the capacitance of the lithium phosphate and improve its electrical conductivity, as well as improve the charging and discharging speed of the high-capacitance electrical core in the present application.In the present application, the mass fraction of the dopant in the active cathode material (including the lithium-containing phosphate and the carbon layer) does not exceed 0.4%, particularly in the range of 0.01% to 0.4%; in particular, titanium can be doped with 0.2% to 0.4%; or titanium can be doped with 0.1% to 0.2% and vanadium can be doped simultaneously with 0.01% to 0.05%. However, the higher the concentration of the dopant, the better it is. The inventor of the present application is conducting research on the charging and discharging of a high-capacitance electric core with thick electrode foils, using lithium iron phosphate as the active cathode material with dopant elements.If the mass fraction of the doping elements in the active cathode substance is more than 0.4%, this leads to large changes in the lattice structure of the lithium iron phosphate, but this does not lead to an improvement in performance.

[0089] In addition to the active cathode substance (where the active cathode substance of the present application comprises a lithium-containing phosphate, which can be coated with carbon and doped with metallic elements), the cathode foil also includes a binder and a conductive agent. The technical solution of the present application is used for a single-sided active substance layer of the cathode foil with a density between 2.3 g / cc and 2.7 g / cc (the density is measured within the first 100 charge and discharge cycles of the lithium-ion battery). In the manufacture of lithium-ion batteries, the electrode foils are typically subjected to roller pressing to increase the density. However, the density of the electrode foils often decreases during the first cycle phase of the finished lithium-ion battery.However, the density of the cathode foil exhibits a lower degree of reduction compared to the anode foil. Furthermore, the areal density of the single-sided substance layer of the cathode foil is between 0.16 mg / mm². 2 and 0.26 mg / mm 2(The areal density is measured within the first 100 charge and discharge cycles of the lithium-ion battery). Furthermore, the thickness of the active substance layer on one side of the cathode foil is between 60 µm and 105 µm. At the points where both surfaces of the cathode collector are coated with the active cathode substance layer, the thickness of the cathode foil of the electrical core with the thick electrode foils is measured in a range of 135 to 225 µm (the thickness of the active substance layer of the cathode foil and the thickness of the cathode foil are measured within the first 100 charge and discharge cycles of the lithium-ion battery).Since the one-sided active substance layer of the cathode foil of the present application is relatively thick, the inventor of the present application further specifies that if the cathode collector is an aluminum foil, if the thickness of the one-sided active substance layer of the cathode foil is less than or equal to 95 µm, a thickness of the cathode collector is measured as D1, and if the thickness of the one-sided active substance layer of the cathode foil is greater than 95 µm, a thickness of the cathode collector is measured as D2, where D2 > D1.It is further specified that the value of D1 is in the range of 11 µm to 13.5 µm, and more preferably from 12 µm to 13 µm; and the value of D2 is in the range of 13.5 µm to 16 µm, and more preferably from 14 µm to 15 µm; because the thicker the thickness of the active substance layer of the cathode foil, the greater the electrically conductive flowability of the required collector, and accordingly a thicker collector is required.

[0090] Due to the considerable thickness of the cathode foil used in the technical solution of the present application to maintain good electrical contact at all positions in the active cathode layer, the present application prefers that the conductive agent in the active cathode layer comprises a carbon tube, and preferably a single-walled or oligo-walled carbon tube. Compared to other conventional conductive materials such as carbon black, the single-walled or oligo-walled carbon tube has better conductivity. On the other hand, the thick electrode foil is likely to make it difficult for the active substance in the upper part of the thick electrode foil to obtain electrons during the cycling process, or may even lead to the thick electrode foil layering phenomenon.The single-walled carbon tube or the oligo-corrugated carbon tube has a larger length-to-thickness ratio than the carbon black, which enables it to fix the thick electrode foil, improve the ability of the upper active substance to retain electrons, and prevent the occurrence of the layering phenomenon. Structure of the cathode foil:

[0091] The cathode foil of the present application comprises a cathode collector and an active cathode substance layer, wherein the cathode collector can be an aluminum foil, a carbon fiber collector or a porous collector, and the active cathode substance layer is combined with the cathode collector such that the active cathode substance layer receives electrons through the cathode collector in the cycle process of the lithium-ion battery.

[0092] The cathode foil further comprises a cathode tab, wherein the cathode tab is electrically connected to the cathode collector and the cathode tab is connected to the cathode collector in various ways, e.g. by welding the cathode tab to the cathode collector or by forming a one-piece structure with the cathode collector (e.g., where the cathode collector is an aluminum foil and the cathode tab is cut and shaped through the cathode collector).

[0093] The cathode collector can have a variety of structures. For example, in a first structure, the cathode collector can be a rectangle with a long edge and a short edge. The long edge of the cathode collector is one length of the rectangular structure, the short edge is one width of the rectangle, the active cathode substance layer is located in at least part of an area of ​​the upper and lower surfaces of the cathode collector, and the cathode tab is located on the short edge of the cathode collector. In a second structure, the cathode collector is also a rectangular structure comprising a long edge and a short edge. The cathode tab is located on the long edge of the cathode collector, and multiple cathode tabs are located on each long edge.The long edge of the cathode collector of the second structure is longer than the long edge of the cathode collector of the first structure. Therefore, it is necessary to arrange a multitude of anode tabs on the cathode collector of the second structure. This helps to reduce heat generation at the tab locations of the electrical core with the thick electrode foils. In the first structure, the cathode foil can be arranged on one or more short edges of the cathode collector. The ratio of the width of the cathode foil to the width of the short edges of the cathode collector is in the range of 0.5 to 0.8, and further in the range of 0.6 to 0.8, not exceeding 0.8. The principle for determining this ratio is the same as for the anode foil, which is not described further here.

[0094] In the present application, the structure of the cathode foil and the manufacturing process of the cathode tab and the cathode foil are similar to those of the anode foil, and the present application is not repeated here; however, it is still necessary to clarify that in some embodiments of the present application, the cathode tabs are also unevenly distributed on the cathode collector, and the distance from the upper end of the cathode tab to the upper end of the cathode foil is a third distance h3, and the distance from the lower end of the cathode tab to the lower end of the cathode foil is a fourth distance h4, where h3 > h4.

[0095] The test procedure for the thickness of the anode foil or the thickness of the cathode foil in the present application is as follows: Discharging the lithium-ion battery with 1 to 100 charge / discharge cycles down to a voltage of 2.5 V, where this voltage is considered the end of the discharge of the lithium-ion battery. Subsequently, disassembling the lithium-ion battery to obtain the cathode foil and the anode foil, and cleaning the cathode foil and the anode foil with a solvent from the electrolyte solution, such as an EC solution, to wash off the lithium salt or other residues on the surface of the cathode foil and the anode foil, followed by drying the solvent and measuring the thickness of the cathode foil and the anode foil.

[0096] The test procedure for the particle size of the active substance in the present application is as follows: Discharging the lithium-ion battery with 1 to 100 charge / discharge cycles down to a voltage of 2.5 V, where this voltage is considered the end of the discharge of the lithium-ion battery. Subsequently, disassembling the lithium-ion battery to obtain the cathode foil and the anode foil, and cleaning the cathode foil and the anode foil with a solvent from the electrolyte solution, such as an EC solution, to wash off the lithium salt or other residues on the surface of the cathode foil and the anode foil, followed by drying of the solvent; subsequent treatment of the electrode foils at high temperature (e.g.,500°C to 600°C) under an inert atmosphere to deactivate the binder in the electrode foil, and after the high-temperature treatment the electrode foil is pulverized to obtain the active substance, followed by sieving (by pressing) of the pulverized active substance and taking a lower particle sample to test the particle size;

[0097] For the round described in the present application (e.g., cycles of 100 rounds), this means that a charging and discharging cycle is recorded as one round. In practice, this does not necessarily have to be a complete charging or discharging cycle; rather, as long as a charging and subsequent discharging cycle occurs before the start of the next charging cycle, it is recorded as one round. Separator: The separator used in the present application comprises a base film, wherein the base film comprises a fiber, the material of the base film comprising PP or PE, the surface of the base film being provided with a coating, the coating comprising an inorganic substance and inorganic particles, the coating being applied to and bonded with the surface of the base film and partially penetrating the interior of the base film, and wherein the presence of the coating is able to effectively prevent the lithium dendrite generated by the anode foil from penetrating the separator and causing an internal short circuit in a lithium-ion battery. However, the coating cannot completely seal the separator, as the electrolyte solution still needs to pass through. Therefore, the porosity of the separator is set at 30% to 50%. Electrolyte solution:

[0098] The electrolyte solution comprises a lithium salt and a solvent, with the lithium salt being lithium hexafluorophosphate (LiPF6). However, lithium hexafluorophosphate has poor thermal stability; at 80 °C, it began to decompose phosphorus pentafluoride (PF5) and lithium fluoride (LiF). Phosphorus pentafluoride (PF5) can react further with water to produce hydrogen fluoride gas, and lithium fluoride (LiF) can react further with solvents such as DMC to produce gas. Therefore, the impact of lithium hexafluorophosphate on gas evolution in the high-capacity electrical core cannot be ignored. Furthermore, as the capacity of lithium-ion batteries increases, the internal accumulation temperature within the electrical core also rises, thus increasing the influence of LiPF6 on gas evolution in the high-capacity electrical core.

[0099] Another lithium salt is lithium bis(fluorosulfonyl)imide (LiFSI). This lithium salt is thermally stable and has a high decomposition temperature of 200°C, which can reduce the problem of gas evolution caused by the temperature increase. Partly due to the high cost of lithium bis(fluorosulfonyl)imide (LiFSI), the lithium salt in the electrolyte solution must still contain lithium hexafluorophosphate (LiPF6). LiFSI has a certain corrosive effect on the aluminum foil of the cathode collector, while LiPF6 can mitigate this corrosive effect. Combined, the molar volume fraction of LiPF6 is higher than that of LiFSI.

[0100] Since the lithium salt is consumed in large quantities during the cycles of the lithium-ion battery, especially during the initial charge / discharge cycle to form the SEI (Single Energy Interruption), the lithium salt content in the finished lithium-ion battery is more closely monitored during the cycle in this application. Specifically, when the number of charge / discharge cycles of the lithium-ion battery is between 5 and 100, the molar volume fraction of the lithium salt is measured in the range of 0.8 mol / L to 1.5 mol / L, where the lithium salt contains lithium hexafluorophosphate (LiPF6) and lithium bis(trifluorosulfonyl)imide (LiFSI). To minimize corrosion of the aluminum foil, the mass fraction of lithium bis(fluorosulfonyl)imide (LiFSI) in the electrolyte solution is further limited to between 0.1% and 9%.

[0101] On the other hand, since gas evolution is increased after the capacity of the lithium-ion battery is increased, if the capacity of the lithium-ion battery is greater than 300 Ah, the mass fraction of LiFSI in the electrolyte solution is not less than 1%.

[0102] Depending on the capacity of the lithium-ion battery and for cost reasons: If the capacity L of the lithium-ion battery is 200 Ah ≤ L ≤ 300 Ah, the mass fraction of LiFSI in the electrolyte solution is 0.1% to 9%, and for cost reasons, it is preferably that the mass fraction of LiFSI in the electrolyte solution is 0.1% to 5%; If the capacity L of the lithium-ion battery is 300 Ah ≤ L ≤ 500 Ah, the mass fraction of LiFSI in the electrolyte solution is 1% to 9%, and for cost reasons, it is preferably that the mass fraction of LiFSI in the electrolyte solution is 1% to 5%; If the capacity L of the lithium-ion battery is 500 Ah < L ≤ 700 Ah, the mass fraction of LiFSI in the electrolyte solution is 3% to 9%; If the capacity L of the lithium-ion battery is 700Ah < L ≤ 1100Ah, the mass fraction of LiFSI in the electrolyte solution is 5% to 9%.In the electrolyte solution of the present application, the solvent comprises EC, DMC, EMC, DEC, and the specific corresponding German names are: Ethylene carbonate (EC), Dimethyl carbonate (DMC), Diethyl carbonate (DEC) and Methyl ethyl carbonate (EMC).Since EC is a cyclic carbonate, it has a high dielectric constant and high ionic conductivity, which can form a stable SEI film on the surface of the anode. However, its viscosity is high, which is not conducive to the diffusion of lithium ions. Therefore, the EC content is between 30% and 40%. DMC and EMC are chain carbonates, and the viscosity of chain carbonate is generally lower than that of cyclic carbonate. For the lithium-ion battery with the thick electrode foils of the present application, it is necessary to ensure that the sum of the masses of DMC and EMC is greater than the mass of EC, and further to ensure that the total content of EMC and DMC is between 50% and 60%.Furthermore, DMC has a lower boiling point compared to EMC and is prone to gas evolution, so the amount of EMC must be higher than the mass of DMC to control gas evolution at high temperatures. However, the lower viscosity of DMC promotes the rise of the electrolyte solution (horizontal and vertical diffusion) on the long electrode foil and separator, which necessitates the presence of DMC and limits its content to 10% to 15%. The EC content is defined as the mass of EC divided by the difference between the mass of the electrolyte solution and the mass of the lithium salt, i.e., mass of EC / (the difference between the mass of the electrolyte solution and the mass of the lithium salt). Similarly, the total EMC and DMC content is defined as the total mass of EMC and DMC divided by the difference between the mass of the electrolyte solution and the mass of the lithium salt.The total mass of EMC and DMC / (the difference between the mass of the electrolyte solution and the mass of the lithium salt); the DMC content refers to the mass of DMC divided by the difference between the mass of the electrolyte solution and the mass of the lithium salt, i.e., the mass of DMC / (the difference between the mass of the electrolyte solution and the mass of the lithium salt).

[0103] In some embodiments, a specific amount of carboxylic ester is also added to the electrolyte solution. This amount is defined as the mass of the carboxylic ester divided by the difference between the mass of the electrolyte solution and the mass of the lithium salt. In other words, the carboxylic ester content is the mass of the carboxylic ester / (the difference between the mass of the electrolyte solution and the mass of the lithium salt). The carboxylic ester contributes to the formation of a film on the anode during charging and discharging of the lithium-ion battery, thereby increasing ionic conductivity and reducing gas evolution at the anode. Conversely, an excessive amount of carboxylic ester leads to an increase in gas evolution, particularly in a fast-charging system. In some embodiments of the present application, the carboxylic ester content is no more than 10%.

[0104] In some embodiments, the carboxylic acid ester can also be used with LiFSI, and both can reduce gas evolution. The most intuitive effect is that the amount of LiFSI can be reduced, thereby lowering costs. If the carboxylic acid ester content is 5% to 10%, the capacity L of the lithium-ion battery is 200 Ah ≤ L ≤ 300 Ah, and the mass fraction of LiFSI in the electrolyte solution is 0.1%–5%; if the capacity L of the lithium-ion battery is 300 Ah < L ≤ 500 Ah, the mass fraction of LiFSI in the electrolyte solution is 1% to 5%; if the capacity L of the lithium-ion battery is 500 Ah < L ≤ 700 Ah, the mass fraction of LiFSI in the electrolyte solution is 2% to 7%. If the capacity L of the lithium-ion battery is 700Ah < L ≤ 1100Ah, the mass fraction of LiFSI in the electrolyte solution is 3% to 8%. Structure of the electrical core: The structure of the electrical core of the present application comprises a cathode foil, an anode foil, and a separator, and the structure of the electrical core of the present application can be a stacked structure or a wound structure. The solution of the present application is applicable to a large electrical core, and the capacity of the lithium-ion battery is between 200Ah and 1100Ah.

[0105] Regardless of whether it is a stacked or wound structure, the electrical core is often oriented vertically during use. The wider the electrical core, the longer the distance the electrolyte solution must travel from the bottom to the top. This electrolyte solution primarily passes through a separator as it travels from the bottom to the top of the electrical core. Particularly in relation to the separator's porosity, especially during the later stages of the lithium-ion battery's cycle, the amount of electrolyte solution inside the casing decreases.If the electrolyte solution at the bottom of the casing cannot rise to the top of the electrical core, the electrode foil at the top of the core will form a large number of lithium dendrites due to the uneven deposition of lithium ions at the anode. This occurs because contact with the electrolyte solution is either impossible or the electrolyte solution is present only in small quantities, leading to increased gas evolution. Conversely, the wider the electrical core, the less likely it is that heat will be dissipated in the center, resulting in a heat concentration there and thus higher gas evolution. A high porosity of the separator also contributes to heat dissipation to some extent.However, the porosity of the separator should not be too high, as this can easily lead to an increase in lithium dendrites at the anode due to uneven current density during charging, resulting in increased gas evolution, especially during high-rate charging. With the electrolyte solution composition of the present application, the porosity of the separator can be 30% to 50% if the anode foil width is between 100 mm and 150 mm; with an anode foil width of 200 mm to 250 mm, the porosity of the separator should be between 35% and 50%.According to the capacity requirements of the above electrical core, it is preferably that the length-to-width ratio of the electrical core is between 6 and 8 when the width of the anode foil is between 100 mm and 150 mm; when the width of the anode foil is between 200 mm and 250 mm, it is preferably that the length-to-width ratio of the electrical core is between 2.8 and 4. Lithium-ion battery: The lithium-ion battery of the present application comprises a housing, an electrical core, and an electrolyte solution, wherein the electrical core and the electrolyte solution are arranged within the housing. The housing is sealed and includes a cathode column, an anode column, and an explosion protection valve. The cathode column is electrically connected to the cathode tab, and the anode column is electrically connected to the anode tab; the cathode column and the anode column can be arranged separately at both ends of the housing or at the same end of the housing.

[0106] The explosion protection valve is arranged at the first end of the housing, and at least one of the cathode columns and one of the anode columns are also arranged at the first end of the housing. Preferably, the explosion protection valve is arranged at the edge of the end of the housing where the cathode column is located; that is, the explosion protection valve is arranged at the first end of the housing, and the cathode column is also arranged at the first end of the housing. A first upper exhaust channel is formed between the upper end of the cathode tab and the housing, wherein, along the airflow direction of the first upper exhaust channel, the projection area of ​​the explosion protection valve partially overlaps with the projection area of ​​the first upper exhaust channel. Furthermore, along the airflow direction of the first upper exhaust channel, the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the first upper exhaust channel exceeds 80%.

[0107] Alternatively, the explosion protection valve is located at the edge of one end of the housing where the anode column is situated; that is, the explosion protection valve is located at the first end of the housing, and the anode column is also located at the first end of the housing. A second upper exhaust channel is formed between the upper end of the anode tab and the housing, with the projection area of ​​the explosion protection valve partially overlapping with the projection area of ​​the second upper exhaust channel along the airflow direction of the second upper exhaust channel. Furthermore, the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the second upper exhaust channel exceeds 80% along the airflow direction of the second upper exhaust channel.

[0108] The degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the first upper exhaust duct is the ratio of the area of ​​an overlap area between the projection area of ​​the explosion protection valve and the projection area of ​​the first upper exhaust duct to the area of ​​the projection area of ​​the first upper exhaust duct along the airflow direction of the first upper exhaust duct. Similarly, the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the second upper exhaust duct is the ratio of the area of ​​an overlap area between the projection area of ​​the explosion protection valve and the projection area of ​​the second upper exhaust duct to the area of ​​the projection area of ​​the second upper exhaust duct along the airflow direction of the second upper exhaust duct.

[0109] The explosion protection valve partially overlaps the projection area of ​​the first upper exhaust duct or the second upper exhaust duct in the direction of airflow. This allows the explosion protection valve to open quickly if the air pressure inside the lithium-ion battery becomes too high under abnormal conditions, thus preventing the air pressure from building up inside the casing and causing an explosion. The degree of overlap between the explosion protection valve and the first upper exhaust duct or the second upper exhaust duct is greater than 80%. This is because the high-capacity electrical core (the lithium-ion battery capacity is greater than or equal to 200 Ah) of the present application generates a significant amount of gas under abnormal conditions. According to the applicant's experiments and simulations, if the degree of overlap were less than 80%, part of the lithium-ion battery would explode.To further prevent the explosion of the lithium-ion battery, the applicant optimizes the electrical core with a high capacity of the present application (the capacity of the lithium-ion battery is greater than or equal to 200Ah) so that the ratio of the area of ​​the explosion protection valve to the capacity of the lithium-ion battery is between 0.5 mm. 2 / Ah and 1.5 mm 2 / Ah. If the capacity of the lithium-ion battery is less than 600Ah, the ratio of the area of ​​the explosion protection valve to the capacity of the lithium-ion battery is less than or equal to 1 mm². 2 / Ah; and if the capacity of the lithium-ion battery is greater than or equal to 600Ah and less than 1200Ah, the ratio of the area of ​​the explosion protection valve to the capacity of the lithium-ion battery is less than or equal to 1.5 mm² 2To further prevent an explosion of the lithium-ion battery, the applicant further optimizes the electrical core with a high capacity of the present application (the capacity of the lithium-ion battery is greater than or equal to 200Ah) such that, if the length-to-width ratio of the electrical core is greater than 2.8, a plurality of explosion protection valves are arranged, and a plurality of explosion protection valves are located in the upper part of the lithium-ion battery, and the upper part of the lithium-ion battery is relative to the location of the lithium-ion battery in the actual places of use of the lithium-ion battery.When the lithium-ion battery is actually in use, at the beginning of its cycle, a large amount of free electrolyte solution remains. If abnormal use occurs at this time and the explosion protection valve opens, the applicant does not want the electrolyte solution to escape along with the gas generated by the explosion protection valve. Since the escaping electrolyte solution will cause further external short circuits, the explosion protection valve must be located in the upper half of the lithium-ion battery. Even if there are multiple explosion protection valves, it is necessary to position each one in the upper half of the lithium-ion battery.

[0110] The explosion protection valve can be located on the short edge of either side of the lithium-ion battery (as shown in...). Fig. 3 of the present application) or on the long edge of the lithium-ion battery, wherein there are various possibilities, such as one of those in Fig. 9 of the possibilities presented in the present application.

[0111] The explosion protection valve is located on the long edge of the housing, the cathode lug is located on the short edge of the cathode collector, the anode lug is located on the short edge of the anode collector, the cathode lug and the anode lug are located at opposite ends of the electrical core, and the cathode lug and / or the anode lug are arranged symmetrically to the electrode foil (the reason for the asymmetrical arrangement in the other methods is, at least in part, to provide space for the explosion protection valve or other devices such as the liquid injection channel). At the same time, the electrode lugs must have a certain width to accommodate their overcurrent capability.If the electrode tabs are shifted downwards relative to the upper edge of the electrode foil, there is a risk that the electrode tabs will come into contact with the housing. Therefore, it is often necessary to check the distance between the lower edge of the electrode tabs and the housing. If the explosion protection valve is located on the long edge of the housing and the electrode tab is located on the short edge of the commutator (the electrode foil is also located on the short edge of the housing), there is no need to worry about the lower edge of the electrode tab being too close to the housing and causing a short circuit.Since the explosion protection valve is located on the long edge at this point, it is possible to arrange the electrode tabs symmetrically to the short edge of the collector and to increase the ratio between the width of the electrode tabs and the short edge of the collector, which can be set to 0.7-0.8, thereby increasing the overcurrent capability of the electrode tabs.

[0112] The present application does not restrict the specific structure of the explosion protection valve, as long as the parts of the housing that can be opened under abnormal conditions can function as the explosion protection valve. For example, if the housing consists of an aluminum-plastic film, the weak zone of the aluminum-plastic film encapsulation can function as the explosion protection valve. The area of ​​the explosion protection valve is calculated as the square of the circumference of the weak zone.

[0113] If there is more than one explosion protection valve, there are a variety of solutions for how two explosion protection valves are arranged. For example, two explosion protection valves can be located on the two opposite short edges of the lithium-ion battery. The two explosion protection valves must be arranged symmetrically; otherwise, one of the explosion protection valves will open but the other will not. Another example is that two explosion protection valves are arranged on the long edge at the top of the lithium-ion battery. In this case, the two explosion protection valves must be distributed symmetrically to the long edge of the lithium-ion battery. Symmetrical distribution here refers to the fact that the distance between each explosion protection valve and the long edge of the lithium-ion battery is the same. This is because, for a long electrical core, if anomalies (e.g., a short circuit) occur, the two valves can malfunction.B. collision) occurring near the center of the electrical core, the collision site can quickly generate a large amount of gas, preventing the gas from being quickly transferred to the explosion protection valve at both ends of the electrical core, which can lead to an explosion of the lithium-ion battery; Another example is that three explosion protection valves are arranged, with two of the explosion protection valves being symmetrically positioned on two opposite short edges of the lithium-ion battery and the third explosion protection valve being positioned on the long edge of the lithium-ion battery and preferably in the middle of the long edge. Because for a long electrical core, if anomalies (e.g.If a collision occurs near the center of the electrical core, the site of the collision can quickly generate a large amount of gas, which prevents the gas from being quickly transferred to the explosion protection valve at both ends of the electrical core, potentially leading to an explosion of the lithium-ion battery.

[0114] If the electrical core is a stacked electrical core, the cathode column and the anode column are arranged at opposite ends of the casing; if the electrical core is a wound electrical core, it is preferably that the cathode column and the anode column are arranged at the same end of the casing. Analysis of gas production:

[0115] During the manufacturing of lithium-ion batteries, a SEI layer forms on the surface of the active substance in the anode foil during the first charge / discharge cycle. This process generates a large amount of gas, which must be pumped out of the lithium-ion battery in a purging step. The sealed casing is then shipped as a finished lithium-ion battery. The use of finished lithium-ion batteries includes normal charge / discharge cycles and abnormal operating environments, such as high temperatures and collisions. In normal operating environments, the charge / discharge cycles continuously dissolve lithium between the graphite layers in the anode, leading to an expansion of the graphite volume and potentially causing the graphite layers to detach, among other things.These factors lead to the destruction and subsequent regeneration of SEI on the surface of the active anode material, and the SEI regeneration process generates gas. Furthermore, when lithium is embedded in graphite, particularly in thick electrode foils, some lithium ions may not be incorporated into the graphite layer in a timely manner. This results in the deposition of lithium dendrites on the surface of the active anode material layer, and some of these deposited lithium dendrites react with the electrolyte solution, generating SEI, consuming the electrolyte solution, and simultaneously producing gas. Gas is also generated at the cathode foil during charge and discharge cycles. Using a ternary material as the active cathode material results in more gas production, but the technical solution of the present application uses lithium-containing phosphate, thus reducing gas production at the cathode. If the lithium-ion battery is used abnormally, e.g.,At high temperatures, the specific reaction part in the lithium-ion battery is shown below:.

[0116] If the temperature of the lithium-ion battery exceeds 80°C, the organic lithium in the SEI film will decompose and produce gas, and the lithium hexafluorophosphate will decompose and react with the solvent, producing gas;

[0117] When the temperature of the lithium-ion battery exceeds 120°C, the SEI film on the surface of the anode has largely decomposed, allowing the lithium and other substances in the anode to react with organic solvents to produce gas;

[0118] When the lithium-ion battery temperature is between 110 °C and 300 °C, the lithium hexafluorophosphate decomposes to a large extent, and the electrolyte solution also reacts with a large amount of gas evolution;

[0119] When the temperature of the lithium-ion battery exceeds 300°C, the lithium-containing phosphate decomposes and produces gas, and the electrolyte also decomposes and produces gas; furthermore, when the temperature of the lithium-ion battery exceeds 235°C, PVDF, which serves as the binder for the cathode foil and the anode foil, also begins to decompose.

[0120] In the early stages of thermal runaway, gas evolution remains relatively low. At this point, immediately stopping the charge / discharge cycles and initiating cooling measures can prevent further progression of the thermal runaway. This allows the lithium-ion battery's anode to regenerate a SEI film, enabling the battery to continue to be used. However, if thermal runaway is not stopped immediately, the significant heat accumulation in the mid to late stages leads to substantial gas evolution. This causes the internal pressure of the lithium-ion battery to rise dramatically, triggering the explosion-proof valve. While the explosion-proof valve prevents an explosive reaction within the lithium-ion battery, once it opens, the battery is no longer usable.

[0121] Therefore, the technical solution of the present application continuously optimizes the structural properties, etc., of the cathode foil, the anode foil, the separator, the electrolyte solution, and the electrical core in the lithium-ion battery. This minimizes gas evolution during normal operation, ensuring that the gases generated during the normal lifetime of the lithium-ion battery (e.g., 3000 charge and discharge cycles) are insufficient to open the explosion protection valve. Furthermore, it ensures that sufficient space is reserved for gases generated during thermal runaway. This prevents the explosion protection valve from opening prematurely in the initial phase of thermal runaway in the lithium-ion battery.If gas evolution during a normal cycle is low and, together with the gases generated in the initial phase of thermal runaway, still does not reach the opening pressure of the explosion protection valve, the explosion protection valve will not open. If further progression of thermal runaway is prevented at this point, the lithium-ion battery can continue to be used. More precisely, the opening pressure of the explosion protection valve is typically between 0.6 MPa and 1 MPa. To increase the safety of lithium-ion batteries, the opening pressure of the explosion protection valve is specified in the present application as being between 0.55 MPa and 0.65 MPa. To provide sufficient gas space for thermal runaway, the present application stipulates that the internal pressure of the lithium-ion battery must not exceed 0.35 MPa after 3000 charge / discharge cycles at 40°C.

[0122] This is because the interior of the casing has a theoretical gas storage space that extends beyond the electrical core and the electrolyte solution. The theoretical gas storage space generally refers to the maximum gas storage capacity provided for in the battery's design. This theoretical gas storage space arises partly from the space between the electrical core and the casing, which is not filled with electrolyte solution during the manufacturing process of the lithium-ion battery. It also arises from the space that becomes available as the electrolyte solution is gradually consumed during the battery's cycle. These two factors together constitute the theoretical gas storage space within the lithium-ion battery. Particularly in the later stages of the lithium-ion battery's cycle, a significant loss of electrolyte solution occurs.The remaining electrolyte solution is largely trapped within the pores of the separator, leaving only a minimal amount of electrolyte solution between the electrical core and the casing. Therefore, when designing the theoretical gas storage space for this application, the space between the electrical core and the casing in the thickness direction of the electrical core is not considered. In the manufacture of lithium-ion batteries, the thickness of the electrical core in its thickness direction is comparable to the thickness of the casing, leaving only minimal reserved space. Furthermore, factors such as the expansion of the electrical core after cycling and the electrolyte solution filling within the electrical core result in the electrical core being almost in contact with the casing in its thickness direction.Consequently, the space between the electrical core and the casing in the thickness direction of the electrical core can be neglected. Furthermore, a significant reduction in the electrolyte solution occurs in the later stages of the cycle. The remaining electrolyte solution is mostly contained within the pores of the separator, leaving only a minimal volume of electrolyte solution between the electrical core and the casing. Therefore, the actual gas storage volume can be calculated by summing the space between the electrical core and the casing in both the width and length directions of the electrical core.

[0123] In particular, the capacity of the electrical core in the present application is preset. Based on the ratio between volume and capacity, the required theoretical gas storage volume Vo can be calculated. For the finished lithium-ion battery, the capacity refers to a charge / discharge rate of 0.33 C.

[0124] The solution of the present application is applicable to several lithium-ion battery structures. An exemplary description is given below with reference to the attached drawings: As in the Fig. 1, Fig. 2, Fig. 3 and Fig. As shown in Figure 4, the square stacked lithium-ion battery has a length-to-width ratio of 6.5. The lithium-ion battery comprises a casing 40 and an electrical core 30, as well as an electrolyte solution (not shown) located inside the casing 40. The cathode foil 10 in Fig. 1 and the anode foil 20 in Fig. 2 together with the separator (not shown) form the electrical core 30 by stacking. The housing 40 further comprises a cathode column 41, an anode column 42 and an explosion protection valve 43.

[0125] Both the cathode foil 10 and the anode foil 20 have a square structure, where "square structure" refers to the overall shape excluding the electrode tabs. The cathode foil 10 comprises a cathode tab 11, a cathode collector, and an active cathode substance layer. The cathode collector has a rectangular structure, with the cathode tab 11 located on a short edge of the cathode collector. The cathode tab 11 has an asymmetrical distribution along the short edge of the cathode collector. Along the lateral direction of the electrical core, i.e.,Along the short edge of the cathode collector, the vertical distance from the upper end of the cathode tab 11 to the upper end of the cathode foil 10 is the first distance h1, and the vertical distance from the lower end of the cathode tab 11 to the lower end of the cathode foil 10 is the second distance h2, where h1 is greater than h2 and the ratio of the width of the cathode tab 11 to the width of the short edge of the cathode collector is 0.75. The anode foil 20 comprises an anode tab 21, an anode collector, and an active anode substance layer. The anode collector has a rectangular structure, with the anode tab 21 arranged along a short edge of the anode collector. The anode tabs 21 are distributed asymmetrically along the short edge of the anode collector. Along the width direction of the electrical core, i.e.,along the short edge of the anode collector, the vertical distance from the upper end of the anode tab 21 to the upper end of the anode foil 20 is the third distance h3, and the vertical distance from the lower end of the anode tab 21 to the lower end of the anode foil 20 is the fourth distance h4, where h3 is greater than h4 and the ratio of the width of the anode tab 21 to the width of the short edge of the anode collector is 0.75.

[0126] The electrical core 30 is formed by stacking a plurality of cathode foils 10, a plurality of anode foils 20, and a separator. A cathode tab 11 is arranged on one short edge of each cathode foil 10, and an anode tab 21 is arranged on one short edge of each anode foil 20. The cathode tab 11 and the anode tab 21 are located at both ends of the electrical core 30.

[0127] The cathode column 41 is electrically connected to the cathode lug 11, while the anode column 42 is electrically connected to the anode lug 21. The cathode column 41 and the anode column 42 are arranged at both ends of the housing 40, with the explosion protection valve 43 being located at the edge of one end of the housing 40 where the cathode column 41 is situated. As shown in the Fig. 3 and Fig. As shown in Figure 4, a first upper exhaust channel 51 is formed between the upper end of the cathode lug 11 and the housing 40, wherein the explosion protection valve 43 is located at the connecting end of the housing 40 with the cathode lug 11, with the airflow direction of the first upper exhaust channel 51 (the horizontal direction in Fig. 4 (where Ld is the longitudinal direction of the electrical core) the explosion protection valve 43 partially overlaps with the first upper exhaust duct 51. In particular, along the airflow direction of the first upper exhaust duct 51, the degree of overlap between the explosion protection valve 43 and the first upper exhaust duct 51 is 85%. That is, along the vertical direction in Fig. 4 (which also corresponds to the vertical direction Hd, where the vertical direction corresponds to the horizontal direction of the lithium-ion battery) the ratio of the width of the explosion protection valve 43 to the width of the first upper exhaust duct 51 is 85%. Fig. Figure 4 shows the direction of gas flow within the lithium-ion battery. The gases generated in the electrical core 30 are largely discharged from the electrical core 30 through the gaps between the electrode foils or along the edges of the electrode foil via the separator. During normal operation, the gases are generated continuously and relatively slowly, and due to their fluidity, they distribute themselves relatively evenly within the housing 40, including a certain concentration at the location of the first upper exhaust duct 51. Under abnormal conditions, gas is generated rapidly, leading to a pressure increase within the housing 40. This increased pressure at the location of the first upper exhaust duct 51 forces the explosion protection valve 43 to open.

[0128] As in Fig. As shown in Figure 3, the gap between the electrical core 30 and the housing 40 is small in the thickness direction of the electrode foil, which is also the thickness direction of the electrical core 30 (in the figure, the thickness direction refers to the direction perpendicular to the plane of view, i.e., perpendicular to Hd and Ld). Since the electrical core 30 expands during the cycle, with the expansion occurring mainly in the thickness direction of the electrical core 30, the gap between the electrical core 30 and the housing 40 is further reduced after the cycle. When calculating the actual gas storage volume, this thickness direction can be neglected. Only the space between the electrical core 30 and the housing 40 along the longitudinal direction of the electrical core 30 and the vertical direction of the electrical core 30 (which is also the horizontal direction) should be considered. This corresponds to the dimensions indicated by reference numerals 1, 2, 3, and 4 in the figure. Fig. 3 designated rooms.

[0129] The Fig. Figures 1 to 4 are for illustrative purposes only; the explosion protection valve 43 can alternatively be arranged at the edge of one end of the housing 40 where the anode column 42 is located. That is, as shown in the Fig. 3 or Fig. As shown in Figure 4, the explosion protection valve 43 can be located on the right short edge of the lithium-ion battery.

[0130] The Fig. 5, Fig. 6, Fig. 9 and Fig. Figure 10 shows another structure of the lithium-ion battery of the present application, wherein the length-to-width ratio of the lithium-ion battery is 3. The lithium-ion battery comprises a housing 40 and an electrical core 30, as well as an electrolyte solution (not shown) located inside the housing 40. The anode foil 20 in Fig. 5 and the cathode foil 10 in Fig. The components 6, together with the separator (not shown), form the electrical core 30 by stacking. The housing 40 further comprises a cathode column 41, an anode column 42, and an explosion protection valve 43. Both the cathode foil 10 and the anode foil 20 have a square structure, where "square structure" refers to the overall shape excluding the electrode tabs. The cathode foil comprises a cathode tab 11, a cathode collector, and an active cathode substance layer. The cathode collector has a rectangular structure, with the cathode tab 11 located along one long edge of the cathode collector. The anode foil 20 comprises an anode tab 21, an anode collector, and an active anode substance layer. The anode collector has a rectangular structure, with the anode tab 21 located along one long edge of the anode collector.The electrical core 30 is formed by stacking a plurality of cathode foils 10, a plurality of anode foils 20, and a separator. A cathode tab 11 is arranged on one long edge of each cathode foil 10, and an anode tab 21 is arranged on one long edge of each anode foil 20. The cathode tab 11 and the anode tab 21 are located at the top of the electrical core 30. The cathode column 41 is electrically connected to the cathode tab 11, while the anode column 42 is electrically connected to the anode tab 21. The cathode column 41 and the anode column 42 are arranged at the top of the housing 40, with the explosion protection valve 43 located between the cathode column 41 and the anode column 42. Fig. Figure 10 shows a schematic representation of the airflow direction. As in Fig. As shown in Figure 9, the gap between the electrical core 30 and the housing 40 in the thickness direction of the electrode foil, which is also the thickness direction of the electrical core 30 (in the figure, the thickness direction refers to the direction perpendicular to the plane of view, i.e., perpendicular to Hd and Ld), is small. Since the electrical core 30 expands during the cycle, with the expansion occurring mainly in the thickness direction of the electrical core 30, the gap between the electrical core 30 and the housing 40 is further reduced after the cycle. When calculating the actual gas storage volume, this thickness direction can be neglected. Only the volume between the electrical core 30 and the housing 40 along the longitudinal and vertical directions of the electrical core 30 should be considered. This corresponds to the values ​​indicated by reference numerals 1, 1, 2, and 3 in Figure 9. Fig. 9 spaces designated. The more precise calculation method is as follows: The volume of the electrical core 30 in the longitudinal direction (i.e., the sum of the volumes designated ① and ②): The difference between the length of the inner cavity of the housing 40 and the length of the electrical core 30, multiplied by the width of the inner cavity of the housing 40 and then multiplied by the thickness of the inner cavity of the housing 40. The volume of the electrical core 30 in the vertical direction (i.e., the volume in the lateral direction or the sum of the volumes designated ③ and ④): The difference between the width of the inner cavity of the housing 40 and the width of the electrical core 30, multiplied by the length of the electrical core 30 and then multiplied by the thickness of the inner cavity of the housing 40.The actual gas storage space is the sum of the volume of the electrical core 30 in the longitudinal direction and the volume of the electrical core 30 in the transverse direction.

[0131] The thickness of the inner cavity of the housing 40 is also referred to in this application as the internal thickness of the housing 40 (i.e., the distance between the inner wall on one side of the housing 40 and the inner wall on the other side of the housing 40 in the thickness direction). The width of the inner cavity of the housing 40 is also referred to in this application as the internal width of the housing 40 (i.e., the distance between the inner wall on one side of the housing 40 and the inner wall on the other side of the housing 40 in the width direction). The length of the inner cavity of the housing 40 is also referred to in this application as the internal length of the housing 40 (i.e., the distance between the inner wall on one side of the housing 40 and the inner wall on the other side of the housing 40 in the length direction).Furthermore, the width of the anode collector (excluding electrode tabs) is replaced by the width of the electrical core 30; the length of the anode collector (excluding electrode tabs) is replaced by the length of the electrical core 30. Although the electrode tabs also occupy some space, the volume occupied by the electrode tabs is not considered in the present application.

[0132] When calculating the actual gas storage volume, the thickness can be disregarded. Only the space between the electrical core 30 and the casing 40 in the longitudinal and vertical directions is considered, specifically the spaces designated by reference symbols 1, 2, and 3. Furthermore, other components between the casing 40 and the electrical core 30, such as the support structure, are excluded. These components also occupy volume, so the actual gas storage volume does not include the volume of these other components.

[0133] The Fig. 7, Fig. 8, Fig. 9 and Fig. Figure 10 shows another structure of the lithium-ion battery of the present application, wherein the length-to-width ratio of the lithium-ion battery is 3. The lithium-ion battery comprises a housing 40 and an electrical core 30, as well as an electrolyte solution (not shown) located inside the housing 40. The cathode foil 10 in Fig. 7 and the anode foil 20 in Fig. The components 8, together with the separator (not shown), form the electrical core 30 by winding. The housing 40 further comprises a cathode column 41, an anode column 42, and an explosion protection valve 43. Both the cathode foil 10 and the anode foil 20 have a square structure, where "square structure" refers to the overall shape excluding the electrode tabs. The cathode foil comprises a cathode tab 11, a cathode collector, and an active cathode substance layer. The cathode collector has a rectangular structure, with the cathode tab 11 arranged along one long edge of the cathode collector, and several cathode tabs 11 evenly spaced on a cathode collector. The anode foil 20 comprises an anode tab 21, an anode collector, and an active anode substance layer.The anode collector has a rectangular structure, with the anode lug 21 arranged along one long edge of the anode collector, and several anode lugs 21 evenly spaced along the anode collector. The cathode foil 10 and the anode foil 20, together with the separator, form the electrical core 30 by winding. The cathode lug 11 and the anode lug 21 are located at the top of the electrical core 30; the cathode column 41 is electrically connected to the cathode lug 11, while the anode column 42 is electrically connected to the anode lug 21. The cathode column 41 and the anode column 42 are arranged at the top of the housing 40, with the explosion protection valve 43 located between the cathode column 41 and the anode column 42. Fig. Figure 10 shows a schematic representation of the airflow direction. As in Fig. As shown in Figure 9, the gap between the electrical core 30 and the housing 40 in the thickness direction of the electrode foil, which is also the thickness direction of the electrical core 30 (in the figure, the thickness direction refers to the direction perpendicular to the plane of view, i.e., perpendicular to Hd and Ld), is small. Since the electrical core 30 expands during the cycle, with the expansion occurring mainly in the thickness direction of the electrical core 30, the gap between the electrical core 30 and the housing 40 is further reduced after the cycle. When calculating the actual gas storage volume, this thickness direction can be neglected. Only the space between the electrical core 30 and the housing 40 along the longitudinal and vertical directions should be considered. This corresponds to the dimensions indicated by reference numerals 1, 1, 2, and 3 in Figure 9. Fig. 9 designated rooms.

[0134] To further investigate the actual gas storage capacity required for different material configurations in various lithium-ion battery systems, the applicant has designed a series of experiments based on his experience in developing low-capacity lithium-ion batteries and previous research. The experimental groups are as follows: [Basic Group 1]

[0135] The applicant initially assembled Basic Group 1 with 100 lithium-ion batteries. The design purpose of Basic Group 1 was to determine the ratio of capacity to gas evolution of the high-capacity electrical core. The materials originally used for the lithium-ion battery and the structure of the lithium-ion battery in Basic Group 1 are as follows: Graphite is used for the active anode material, with an OI value of 10, a degree of graphitization of 92%, a graphite size of 50° (Dv50) of 15 µm, a graphite size of 10° (Dv10) of 6 µm, a graphite size of 90° (Dv90) of 26 µm, and a graphite size of 99° (Dv99) of 42 µm. The graphite consists of non-agglomerated particles. The areal density of the single-sided active layer of the anode foil is 0.11 mg / mm². 2The density of the active substance layer on one side of the anode foil is 1.4 g / cc. The thickness of the active anode substance layer on one side is 79 µm. The anode collector is a copper foil with a thickness of 6 µm. Both surfaces of the anode collector are coated with the active anode substance layer. The anode tab is located at one end of the anode foil along its length, specifically at the short edge. The anode tab forms a single unit with the anode foil. The width of the anode foil is 120 mm, while the width of the anode tab is 75 mm. Along the width of the anode foil, the distance h3 from the top of the anode tab to the top of the anode foil is 28 mm, and the distance h4 from the bottom of the anode tab to the bottom of the anode foil is 17 mm. Several anode foils are arranged, each of which is provided with an anode tab.These anode tabs are electrically connected to the anode column at the second end of the housing. The first end of the housing is equipped with an explosion protection valve. The active anode material consists of carbon-coated lithium iron phosphate (LFP). The density of the single-sided active layer of the cathode foil is 2.6 g / cc. The areal density of the single-sided active layer of the cathode foil is 0.24 mg / mm². 2The thickness of the single-sided active substance layer of the cathode foil is 92 µm. The cathode tab is located at one end of the cathode foil in the longitudinal direction, specifically at the short edge. The cathode tab forms a single unit with the cathode foil. The width of the cathode foil is 116 mm, while the width of the cathode tab is 75 mm. The distance h1 from the upper end of the cathode tab to the upper end of the cathode foil is 26 mm, and the distance h2 from the lower end of the cathode tab to the lower end of the cathode foil is 15 mm. Several cathode foils are arranged, each with its own cathode tab. These cathode tabs are electrically connected to the cathode column at the other end of the housing. A first upper exhaust channel is formed between the upper end of the cathode tab and the housing. The first end of the housing is equipped with an explosion protection valve.The explosion protection valve is located above the cathode column. Along the airflow direction of the first upper exhaust channel, the degree of overlap between the explosion protection valve and the first upper exhaust channel is 85%. The average particle size of the primary particles of the active cathode substance LFP is 0.1 µm to 5 µm (due to the inherent tendency of LFP particles to agglomerate, an exact measurement of their average particle size is not possible. However, since LFP generates significantly less gas compared to the ternary cathode material, and the gas evolution at the graphite position of the anode far exceeds the gas evolution at the LFP position of the cathode when LFP and graphite form a lithium-ion battery, there are therefore no restrictions regarding the particle size of LFP as a cathode material in the present application).

[0136] The separator comprises a PE base film, the base film being coated with aluminium oxide, with the porosity of the separator being 40%.

[0137] The lithium salt in the electrolyte solution is LiPF6, and its mass fraction in the electrolyte solution is 16%. The solvent of the electrolyte solution comprises ethylene carbonate (EC), dimethyl carbonate (DMC), ethylene methyl carbonate (EMC), and diethyl carbonate (DEC), with mass fractions of 30%, 13%, 38%, and 8%, respectively.

[0138] The electrical core has a stacked structure; the lithium-ion battery has a capacity of 300 Ah. The gas storage volume for the base group 1 of the lithium-ion battery is 1500 cm³. 3The gas storage space of base group 1 of the lithium-ion battery is significantly larger than the required space for several reasons: Firstly, this ensures that each base group can undergo 3000 cycles during testing without the explosion protection valve being activated, thus enabling the calculation of the capacity-to-gas evolution ratio across different base groups of the lithium-ion battery. Secondly, the larger gas storage space in base group 1 of the lithium-ion battery facilitates the installation of a gas pressure sensor in the housing. After injection with electrolyte solution, lithium-ion batteries undergo formation and degassing processes.

[0139] The opening pressure of the explosion protection valve is 0.6 MPa.

[0140] The casing of the lithium-ion battery is made of an aluminum alloy, and a gas pressure sensor is arranged inside the casing.

[0141] For the 100 lithium-ion batteries in base group 1, the ambient temperature during the charge / discharge cycles was 40°C. The cutoff voltage was between 2.5 V and 3.65 V, with the charging process comprising a constant current phase and a constant voltage phase. Constant current phase: charging the lithium-ion batteries at a rate of 1C up to the cutoff voltage (3.65 V). Constant voltage phase: charging at a constant voltage. The discharge process comprised discharging the lithium-ion battery at a rate of 1C up to the discharge cutoff voltage (2.5 V). After 50 charge / discharge cycles for the base group, 5 lithium-ion batteries were selected for disassembly and analysis of component changes. The remaining 95 lithium-ion batteries were cycled for up to 3000 cycles.Analysis of the five lithium-ion batteries removed revealed that most of the cathode and anode materials and the cathode and anode foils showed only minimal changes, with the exception of variations in the density and thickness of the anode foil. The density of the single-sided active substance layer of the anode foil was determined to be 1.35 g / cm³. 3 The thickness of the anode foil was measured at 85 µm. Changes in the compression density and the thickness of the single-sided active substance layer of the cathode foil were relatively small. The compression density of the single-sided active substance layer of the cathode foil was determined to be 2.59 g / cm³. 3 measured, with the thickness of the one-sided active substance layer of the cathode foil being 93 µm.

[0142] The explosion protection valves of the remaining 95 lithium-ion batteries did not open after 3000 cycles. After reaching 3000 cycles, the gas pressure P recorded by the gas pressure sensor in each lithium-ion battery was recorded (the pressure P can vary between different lithium-ion batteries). Using the equation PV=NRT with T=40°C, R=8.314, V=1500 cm³ 3 The gas evolution N is calculated for each lithium-ion battery using the pressure P in MPa. Based on a compilation of 95 data points, it is shown that for a lithium-ion battery capacity L of 300 Ah, the ratio of gas evolution N to the capacity N / L of the lithium-ion battery lies between 0.02554 mmol / Ah (millimoles per ampere-hour) and 0.03495 mmol / Ah.

[0143] Using the equation Pv = NRT with a fixed gas pressure P of 0.35 MPa, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / PL. Assuming T is 40 °C, R is 8.314, and N / L is between 0.02554 mmol / Ah and 0.03495 mmol / Ah, the result is 0.19 cm³. 3 / Ah ≤ v / L ≤ 0.26 cm 3 / Ah, i.e. 0.19 L ≤ v ≤ 0.26 L, where v is given in cubic centimeters (cm³). 3 ). [Adjustment group 1]

[0144] Based on Base Group 1, Adaptation Group 1 was formed. The concept of Adaptation Group 1 was to develop a series of graphite lithium-ion batteries with different OI values ​​based on Base Group 1, while all other properties remained identical to those of Base Group 1.

[0145] After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the OI value of graphite was 3, the average gas evolution to capacity ratio for several lithium-ion batteries in the adjustment group 1 approached the upper limit of the base group 1 (0.03495 mmol / Ah). When the OI value of graphite was below 3, the average gas evolution to capacity ratio for several lithium-ion batteries in the adjustment group 1 exceeded the upper limit of the base group 1 (0.03495 mmol / Ah).Consequently, the average ratio of gas evolution to capacity for the corresponding multiple lithium-ion batteries in adaptation group 1 is below the upper limit of base group 1 (0.03495 mmol / Ah) when the OI value of the graphite is greater than 3 and less than or equal to 30 (for cost reasons, cases where the OI value exceeded 30 are not examined in the present application. However, based on the inventor's assumption, the higher the OI value of the graphite, the better the fast-charging capability and the lower the gas evolution). [Adjustment group 1.2]

[0146] Based on adaptation group 1, an adaptation group 1.2 is formed. The only difference between adaptation group 1.2 and adaptation group 1 is that the charging rate is adjusted to 2C.

[0147] It was found that when the OI value of graphite is 10, the average gas evolution to capacity ratio for multiple lithium-ion batteries in adjustment group 1.2 approached the upper limit of base group 1 (0.03495 mmol / Ah). When the OI value of graphite is below 10, the average gas evolution to capacity ratio for multiple lithium-ion batteries in adjustment group 1.2 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). Consequently, when the OI value of graphite is greater than 10 and less than or equal to 30, the average gas evolution to capacity ratio for the corresponding multiple lithium-ion batteries in adjustment group 1.2 is below the upper limit of base group 1 (0.03495 mmol / Ah). [Adaptation group 1.3]

[0148] Based on adaptation group 1, an adaptation group 1.3 is formed. The only difference between adaptation group 1.3 and adaptation group 1 is the charging rate, which is adjusted to 3C.

[0149] It was found that when the OI value of graphite is 15, the average gas evolution to capacity ratio for multiple lithium-ion batteries in adjustment group 1.3 approaches the upper limit of base group 1 (0.03495 mmol / Ah). When the OI value of graphite is below 15, the average gas evolution to capacity ratio for multiple lithium-ion batteries in adjustment group 1.3 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). Consequently, when the OI value of graphite is greater than 15 and less than or equal to 30, the average gas evolution to capacity ratio for the corresponding multiple lithium-ion batteries in adjustment group 1.3 is below the upper limit of base group 1 (0.03495 mmol / Ah).

[0150] Based on the results of base group 1, adjustment group 1, adjustment group 1.2, and adjustment group 1.3, it can therefore be summarized that, given a required charging power of the electrical core at a high charging rate, for example, at a rate greater than 2C, the OI value of the graphite can be set to 10 to 30. At a rate greater than 3C, the OI value of the graphite can be set to 15 to 30. [Adjustment group 2]

[0151] Based on base group 1, adaptation group 2 was formed. The concept of adaptation group 2 was to develop a series of lithium-ion batteries with graphite and varying degrees of graphitization based on base group 1, while all other properties remained identical to those of base group 1.

[0152] After 3000 cycles, the ratio of gas evolution to capacity was determined for this series of lithium-ion batteries. It was found that when the graphitization degree of graphite is 90%, the average ratio of gas evolution to capacity for several lithium-ion batteries in adjustment group 2 approached the upper limit of the base group 1 (0.03495 mmol / Ah).

[0153] If the graphitization degree of the graphite is below 90%, the average ratio of gas evolution to capacity for multiple lithium-ion batteries in adaptation group 2 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). Conversely, the average ratio of gas evolution to capacity for the corresponding multiple lithium-ion batteries in adaptation group 2 is below the upper limit of base group 1 (0.03495 mmol / Ah) if the graphitization degree of the graphite is greater than 90% and less than or equal to 95%. (For cost reasons, cases where the graphitization degree exceeded 95% are not examined in this application. However, based on the inventor's assumption, the higher the graphitization degree of the graphite, the better the fast-charging capability and the lower the gas evolution.) [Adjustment group 2.2]

[0154] Based on adaptation group 2, adaptation group 2.2 was formed. The concept of adaptation group 2.2 was to set the charging rate at 2C based on base group 1, while all other properties remained identical to those of adaptation group 2.

[0155] After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the graphitization degree of graphite was 91%, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 2.2 approached the upper limit of base group 1 (0.03495 mmol / Ah). When the graphitization degree of graphite was below 91%, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 2.2 exceeded the upper limit of base group 1 (0.03495 mmol / Ah). [Adaptation group 3]

[0156] Based on base group 1, an adaptation group 3 was formed. The concept of adaptation group 3 was to develop a series of graphite lithium-ion batteries with different Dv50 values ​​based on base group 1, while all other properties remained identical to those of base group 1.

[0157] After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the graphite's Dv50 was 10 µm, the average gas evolution to capacity ratio for several lithium-ion batteries in the adaptation group 3 approached the upper limit of the base group 1 (0.03495 mmol / Ah). When the graphite's Dv50 was below 10 µm, the average gas evolution to capacity ratio for several lithium-ion batteries in the adaptation group 3 exceeded the upper limit of the base group 1 (0.03495 mmol / Ah). It was shown that when Dv50 of graphite is 30 µm, the average ratio of gas evolution to capacity for several lithium-ion batteries in the fitting group 3 approached the upper limit of the base group 1 (0.03495 mmol / Ah).If the graphite's Dv50 is above 30 µm, the average gas evolution to capacity ratio for multiple lithium-ion batteries in adaptation group 3 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). If the graphite's Dv50 is between 10 µm and 30 µm, the average gas evolution to capacity ratio for the corresponding multiple lithium-ion batteries in adaptation group 3 is below the upper limit of base group 1 (0.03495 mmol / Ah). [Adjustment group 3.2]

[0158] Based on adaptation group 3, an adaptation group 3.2 is created. The only difference between adaptation group 3 and adaptation group 3.2 is the charging rate, which is adjusted to 2C.

[0159] It was found that when the Dv50 of graphite is 20 µm, the average gas evolution to capacity ratio for multiple lithium-ion batteries in fitting group 3.2 approaches the upper limit of base group 1 (0.03495 mmol / Ah). When the Dv50 of graphite is above 20 µm, the average gas evolution to capacity ratio for multiple lithium-ion batteries in fitting group 3.2 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). Consequently, when the Dv50 of graphite is between 10 µm and 20 µm, the average gas evolution to capacity ratio for the corresponding multiple lithium-ion batteries in fitting group 3.2 is below the upper limit of base group 1 (0.03495 mmol / Ah). [Adjustment group 3.3]

[0160] Based on adaptation group 3, an adaptation group 3.3 is formed. The only difference between adaptation group 3 and adaptation group 3.3 is that the graphite used is the carbon-coated secondary particles of graphite.

[0161] It was found that when the Dv50 of carbon-coated secondary particles of graphite is 30 µm, the average ratio of gas evolution to capacity for several lithium-ion batteries in the 3.3 adaptation group approaches the upper limit of the base group 1 (0.03495 mmol / Ah). When the Dv50 of carbon-coated secondary particles of graphite is above 30 µm, the average ratio of gas evolution to capacity for several lithium-ion batteries in the 3.3 adaptation group exceeds the upper limit of the base group 1 (0.03495 mmol / Ah). Consequently, the average ratio of gas evolution to capacity for the corresponding multiple lithium-ion batteries in adaptation group 3.3 is below the upper limit of base group 1 (0.03495 mmol / Ah) when Dv50 of carbon-coated secondary particles of graphite is between 10 µm and 30 µm. [Adjustment group 3.4]

[0162] Based on base group 1, an adaptation group 3.4 was formed. The concept of adaptation group 3.4 was to develop a series of graphite lithium-ion batteries with different Dv10 values ​​based on base group 1, while all other properties remained identical to those of base group 1.

[0163] After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the Dv10 of graphite is 3 µm, the average gas evolution to capacity ratio for several lithium-ion batteries in adaptation group 3.4 approached the upper limit of base group 1 (0.03495 mmol / Ah). When the Dv10 of graphite is below 3 µm, the average gas evolution to capacity ratio for several lithium-ion batteries in adaptation group 3.4 exceeded the upper limit of base group 1 (0.03495 mmol / Ah). [Adjustment group 3.5]

[0164] Based on base group 1, an adaptation group 3.5 was formed. The concept of adaptation group 3.5 was to develop a series of graphite lithium-ion batteries with different Dv90 values ​​based on base group 1, while all other properties remained identical to those of base group 1.

[0165] After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the Dv90 of graphite is 40 µm, the average gas evolution to capacity ratio for several lithium-ion batteries in adaptation group 3.5 approaches the upper limit of base group 1 (0.03495 mmol / Ah). When the Dv90 of graphite is below 40 µm, the average gas evolution to capacity ratio for several lithium-ion batteries in adaptation group 3.5 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). [Adaptation group 3.6]

[0166] Based on base group 1, an adaptation group 3.6 was formed. The concept of adaptation group 3.6 was to develop a series of graphite lithium-ion batteries with different Dv99 values ​​based on base group 1, while all other properties remained identical to those of base group 1.

[0167] After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the Dv99 of graphite is 49 µm, the average gas evolution to capacity ratio for several lithium-ion batteries in adaptation group 3.6 approaches the upper limit of base group 1 (0.03495 mmol / Ah). When the Dv99 of graphite is below 49 µm, the average gas evolution to capacity ratio for several lithium-ion batteries in adaptation group 3.6 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). [Adjustment group 4]

[0168] Based on base group 1, an adaptation group 4 was formed. The concept of adaptation group 4 was to develop a series of lithium-ion batteries with anode foils of different areal densities based on base group 1, while all other properties remained identical to those of base group 1.

[0169] After 3000 cycles, the ratio of gas evolution to capacity was determined for this series of lithium-ion batteries. It was found that when the areal density of the one-sided active substance layer of the anode foil was 0.13 mg / mm² 2 The average ratio of gas evolution to capacity for several lithium-ion batteries in adaptation group 4 approached the upper limit of base group 1 (0.03495 mmol / Ah). If the areal density of the one-sided active substance layer of the anode foil exceeded 0.13 mg / mm² 2If the average ratio of gas evolution to capacity for several lithium-ion batteries in adaptation group 4 exceeds the upper limit of base group 1 (0.03495 mmol / Ah), and the areal density of the one-sided active substance layer of the anode foil is between 0.07 mg / mm² 2 - and 0.13 mg / mm 2 The average ratio of gas evolution to capacity for the corresponding several lithium-ion batteries in adaptation group 4 is below the upper limit of base group 1 (0.03495 mmol / Ah). If the areal density of the one-sided active substance layer of the anode foil is below 0.07 mg / mm² 2The presence of the anode collector results in a relatively small amount of active substance on the anode foil across the entire anode foil. This is particularly important for high-capacity electrical cores exceeding 200 Ah, which require a larger number of anode foils to achieve the necessary capacitance. Consequently, the volume fraction of the collector increases in high-capacity electrical cores. Based on the inventor's previous practice, the present application therefore provides, in certain embodiments, that the areal density of the one-sided active substance layer of the anode foil must be at least 0.07 mg / mm². 2 May amount to… [Adjustment group 5]

[0170] Based on base group 1, an adaptation group 5 was formed. The concept of adaptation group 5 was to develop a series of lithium-ion batteries with anode foils of varying densities after roller pressing, based on base group 1, while all other properties remained identical to those of base group 1. After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the density of the one-sided active substance layer of the anode foil after roller pressing was 1.74 g / cc, the average gas evolution to capacity ratio for several lithium-ion batteries in adaptation group 5 approached the upper limit of base group 1 (0.03495 mmol / Ah).If the density of the single-sided active layer of the anode foil after roller pressing exceeds 1.74 g / cc, the average ratio of gas evolution to capacity for several lithium-ion batteries in adaptation group 5 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). If the density of the single-sided active layer of the anode foil after roller pressing is between 1.32 g / cc and 1.74 g / cc, the average ratio of gas evolution to capacity for the corresponding several lithium-ion batteries in adaptation group 5 is below the upper limit of base group 1 (0.03495 mmol / Ah). If the density of the single-sided active layer of the anode foil after roller pressing is below 1.32 g / cc, the principle is the same as for the areal density; the mass fraction of the anode collector is very high for the entire anode foil.This is particularly important for high-capacity electrical cores exceeding 200 Ah, which require a larger number of anode foils to achieve the necessary capacity. Consequently, the mass fraction of the collector increases in high-capacity electrical cores. Based on the inventor's previous practice, the present application therefore stipulates that the areal density of the single-sided active layer of the anode foil must not be less than 1.32 g / cc. In adaptation group 5, several lithium-ion batteries with an anode foil having a density of 1.74 g / cc for the single-sided active layer were disassembled after roller pressing following 50 cycles. It was determined that the density of the single-sided active layer of the anode foil was 1.7 g / cc. Several lithium-ion batteries with an anode foil having a density of 1.32 g / cc for the single-sided active layer were disassembled after roller pressing following 50 cycles.It was determined that the density of the one-sided active substance layer of the anode foil is 1.3 g / cc. [Adjustment group 6]

[0171] Based on base group 1, an adaptation group 6 was formed. The concept of adaptation group 6 was to develop a series of lithium-ion batteries with cathode foils of different areal densities after roller pressing based on base group 1, while all other properties remained identical to those of base group 1.

[0172] After 3000 cycles, the ratio of gas evolution to capacity was determined for this series of lithium-ion batteries. It was found that when the areal density of the one-sided active substance layer of the cathode foil was 0.26 mg / mm² after roller pressing... 2The average ratio of gas evolution to capacity for several lithium-ion batteries in adjustment group 6 approached the upper limit of base group 1 (0.03495 mmol / Ah). This was observed when the areal density of the one-sided active substance layer of the cathode foil after roller pressing exceeded 0.26 mg / mm². 2 If the average ratio of gas evolution to capacity for several lithium-ion batteries in adaptation group 6 exceeds the upper limit of base group 1 (0.03495 mmol / Ah), the areal density of the one-sided active substance layer of the cathode foil after roller pressing is between 0.16 mg / mm². 2 and 0.26 mg / mm 2The average ratio of gas evolution to capacity for the corresponding several lithium-ion batteries in adaptation group 6 is below the upper limit of base group 1 (0.03495 mmol / Ah). If the areal density of the one-sided active substance layer of the cathode foil is below 0.16 mg / mm² 2 The presence of the cathode collector results in a relatively small amount of active substance on the cathode foil across the entire surface. This is particularly important for high-capacity electrical cores exceeding 200 Ah, which require a larger number of cathode foils to achieve the necessary capacitance. Consequently, the volume fraction of the collector increases in high-capacity electrical cores. Based on the inventor's previous practice, the present application therefore stipulates that the areal density of the one-sided active substance layer of the cathode foil must be at least 0.16 mg / mm². 2 May amount to… [Adjustment group 7]

[0173] Based on base group 1, an adaptation group 7 was formed. The concept of adaptation group 7 was to develop a series of lithium-ion batteries with cathode foils of different pressing densities after roller pressing, based on base group 1, while all other properties remained identical to those of base group 1.

[0174] After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the density of the single-sided active substance layer of the cathode foil after roller pressing was 2.71 g / cc, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 7 approached the upper limit of base group 1 (0.03495 mmol / Ah). When the density of the single-sided active substance layer of the cathode foil after roller pressing exceeded 2.71 g / cc, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 7 exceeded the upper limit of base group 1 (0.03495 mmol / Ah).If the density of the single-sided active substance layer of the cathode foil after roller pressing is between 2.3 g / cc and 2.71 g / cc, the average ratio of gas evolution to capacity for the corresponding multiple lithium-ion batteries in adaptation group 7 is below the upper limit of base group 1 (0.03495 mmol / Ah). If the density of the single-sided active substance layer of the cathode foil after roller pressing is below 2.3 g / cc, the principle being the same as for the areal density is that the mass fraction of the cathode collector is very high for the entire cathode foil. This is particularly important for high-capacity electrical cores above 200 Ah, which require a larger number of cathode foils to achieve the required capacity. Consequently, the mass fraction of the collector increases in high-capacity electrical cores.Based on the inventor's previous practice, the present application therefore stipulates that the areal density of the one-sided active substance layer of the cathode foil must not be less than 2.3 g / cc. In adaptation group 7, several lithium-ion batteries with a cathode foil having a density of 2.71 g / cc for the one-sided active substance layer were disassembled after roller pressing following 50 cycles. It was determined that the density of the one-sided active substance layer of the anode foil was 2.7 g / cc. Several lithium-ion batteries with a cathode foil having a density of 1.3 g / cc for the one-sided active substance layer were also disassembled after roller pressing following 50 cycles. It was determined that the density of the one-sided active substance layer of the cathode foil was 1.3 g / cc. At low pressing densities, the density of the cathode foil shows almost no change. [Adjustment group 8]

[0175] Based on base group 1, an adaptation group 8 was formed. The concept of adaptation group 8 was to develop a series of lithium-ion batteries with separators of different porosities based on base group 1, while all other properties remained identical to those of base group 1.

[0176] After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the separator porosity was 50%, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 8 approached the upper limit of the base group 1 (0.03495 mmol / Ah). When the separator porosity exceeded 50%, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 8 exceeded the upper limit of the base group 1 (0.03495 mmol / Ah). It was found that when the porosity of the separator is 30%, the average ratio of gas evolution to capacity for several lithium-ion batteries in the adaptation group 8 approached the upper limit of the base group 1 (0.03495 mmol / Ah).If the separator porosity is below 30%, the average gas evolution to capacity ratio for multiple lithium-ion batteries in adaptation group 8 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). If the separator porosity is between 30% and 50%, the average gas evolution to capacity ratio for the corresponding multiple lithium-ion batteries in adaptation group 8 is below the upper limit of base group 1 (0.03495 mmol / Ah). Based on base group 1, adaptation group 8.2 was created. The difference between adaptation group 8.2 and base group 1 lies in the different widths of the anode foil (with corresponding variations in the width of the electrical core, the width of the cathode foil, the width of the anode tab, and the width of the cathode tab). This design includes a range of lithium-ion batteries with anode foils of different widths.After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the anode foil width is 250 mm, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 8.2 approached the upper limit of base group 1 (0.03495 mmol / Ah). When the anode foil width exceeds 250 mm, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 8.2 exceeded the upper limit of base group 1 (0.03495 mmol / Ah). Consequently, the average gas evolution to capacity ratio for the corresponding several lithium-ion batteries in adjustment group 8.2 below the upper limit of Base Group 1 (0.03495 mmol / Ah) if the anode foil width is between 100 mm and 250 mm (in conventional high-capacity electrical core designs, the anode foil width is greater than 100 mm; therefore, cases below 100 mm were not examined in the present application). Based on Base Group 1, an adaptation group 8.3 was formed. The difference between adaptation group 8.3 and Base Group 1 lies in the anode foil width of 200 mm (with corresponding variations in the electrical core width, cathode foil width, anode tab width, and cathode tab width). This design comprises a series of lithium-ion batteries with separators of varying porosities. After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries.It was found that when the separator porosity is 35%, the average gas evolution to capacity ratio for multiple lithium-ion batteries in adjustment group 8.3 approached the upper limit of base group 1 (0.03495 mmol / Ah). When the separator porosity is below 35%, the average gas evolution to capacity ratio for multiple lithium-ion batteries in adjustment group 8.3 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). When the separator porosity is between 35% and 50%, the average gas evolution to capacity ratio for the corresponding multiple lithium-ion batteries in adjustment group 8.3 is below the upper limit of base group 1 (0.03495 mmol / Ah). Based on base group 1, an adjustment group 8.4 was formed. The difference between adjustment group 8.4 and base group 1 lie in the width of the anode foil of 150 mm (with corresponding deviations in the width of the electrical core, the width of the cathode foil, the width of the anode tab, and the width of the cathode tab). This design comprises a series of lithium-ion batteries with separators of varying porosities. After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the separator porosity is 30%, the average gas evolution to capacity ratio for several lithium-ion batteries in fitting group 8.4 approached the upper limit of base group 1 (0.03495 mmol / Ah). If the separator porosity is below 30%, the average ratio of gas evolution to capacity for several lithium-ion batteries in adaptation group 8 exceeds 8.4 the upper limit of base group 1 (0.03495 mmol / Ah). If the separator porosity is between 30% and 50%, the average ratio of gas evolution to capacity for the corresponding multiple lithium-ion batteries in adjustment group 8.4 is below the upper limit of base group 1 (0.03495 mmol / Ah). [Adjustment group 9]

[0177] Based on the first base group, an adaptation group 9 was formed. The concept of adaptation group 9 was to develop a series of lithium-ion batteries with electrolyte solutions containing varying concentrations of dimethyl methacrylate (DMC), based on the first base group. The DMC concentration is defined as the mass of DMC divided by the difference between the mass of the electrolyte solution and the mass of the lithium salt. Changes in the DMC concentration correspondingly alter the ratios of the solvents in the electrolyte solution, such as electrolyte (EC), dimethyl methacrylate (DMC), electrolyte-methyl methacrylate (EMC), and deionized electrolyte (DEC). However, based on the inventor's experience and experimental investigations, it is necessary to maintain the EC concentration in the range of 30% to 40%. The sum of the masses of EMC and DMC divided by the difference between the mass of the electrolyte solution and the mass of the lithium salt should be between 50% and 60%.(At this concentration, the sum of the masses of EC, EMC, and DMC divided by the difference between the mass of the electrolyte solution and the mass of the lithium salt may occasionally be less than 100% due to the presence of other additives in the electrolyte solution.) While a high DMC concentration reduces the viscosity of the electrolyte solution, thereby reducing gas evolution and facilitating fast charging, DMC generates significant amounts of gas during the charge and discharge cycles of lithium-ion batteries. Therefore, DMC must be kept within a certain range for the lithium-ion batteries covered by this application. After 3000 cycles, the ratio of gas evolution to capacity was determined for this series of lithium-ion batteries.It was found that when the DMC content was 10%, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 9 approached the upper limit of the base group 1 (0.03495 mmol / Ah). When the DMC content was below 10%, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 9 exceeded the upper limit of the base group 1 (0.03495 mmol / Ah). It was also found that when the DMC content was 15%, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 9 approached the upper limit of the base group 1 (0.03495 mmol / Ah). If the DMC content exceeds 15%, the average ratio of gas evolution to capacity for several lithium-ion batteries in adaptation group 9 exceeds the upper limit of base group 1 (0.03495 mmol / Ah).If the DMC content is between 10% and 15%, the average ratio of gas evolution to capacity for the corresponding multiple lithium-ion batteries in adaptation group 9 is below the upper limit of base group 1 (0.03495 mmol / Ah). [Adjustment group 10]

[0178] Based on Base Group 1, an adaptation group 10 was formed. The concept of adaptation group 10 was to develop a series of lithium-ion batteries with electrolyte solutions containing varying concentrations of carboxylic esters, based on Base Group 1. The carboxylic ester concentration is defined as the mass of the carboxylic ester divided by the difference between the mass of the electrolyte solution and the mass of the lithium salt. The carboxylic ester facilitates film formation on the anode during the charge and discharge cycles of lithium-ion batteries and improves ionic conductivity. This supports fast charging and reduces gas evolution at the anode interface. Conversely, an excessive concentration of carboxylic esters leads to an increase in gas evolution, especially in a fast-charging system. The carboxylic ester concentration must therefore remain within a specific range.

[0179] After 3000 cycles, the gas evolution to capacity ratio was determined for this series of lithium-ion batteries. It was found that when the carboxylic acid ester content is below 10%, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 10 is below the upper limit of base group 1 (0.03495 mmol / Ah). When the carboxylic acid ester content is 10%, the average gas evolution to capacity ratio for several lithium-ion batteries in adjustment group 10 approaches the upper limit of base group 1 (0.03495 mmol / Ah). If the content of carboxylic acid esters exceeds 10%, the average ratio of gas evolution to capacity for the corresponding several lithium-ion batteries in adaptation group 10 exceeds the upper limit of base group 1 (0.03495 mmol / Ah). [Adjustment group 11]

[0180] Based on base group 1, an adaptation group 11 was formed. Adaptation group 11 requires only 10 lithium-ion batteries, and the difference from base group 1 lies in the charging procedures. During the constant current phase, charging is no longer performed with a constant current, but rather in a staggered and distributed manner with high and low currents. The specific procedure is as follows: charging at a rate of 1C for 2 minutes, then charging at a rate of 0.2C for 0.5 minutes, then again charging at a rate of 1C for 2 minutes, alternating until the charging cutoff voltage is reached and constant voltage charging is activated. Using this high- and low-current charging procedure, the lithium-ion batteries in each of adaptation groups 11 are, according to 3...000 cycles in gas evolution reduced compared to the corresponding lithium-ion batteries in the corresponding base group 1, and other conditions are the same as those of base group 1. [Adjustment group 12]

[0181] Based on base group 1, an adaptation group 12 was created. Adaptation group 12 requires only 10 lithium-ion batteries, and the difference from base group 1 lies in the charging procedures. During the constant current phase, charging is no longer performed with a constant current, but rather in a staggered and distributed manner with high and low currents. The specific procedure is as follows: charging at a rate of 1C for 2 minutes, then charging at a rate of 0.2C for 0.5 minutes, then charging again at a rate of 0.8C for 2 minutes, then charging again at a rate of 0.2C for 0.5 minutes. In this way, the high current is gradually reduced until the charging cutoff voltage is reached and constant voltage charging is activated.

[0182] Using the charging method with a high and low current distribution of this group, the lithium-ion batteries in each of the adaptation groups 12 show reduced gas evolution after 3,000 cycles compared to the corresponding lithium-ion batteries in the corresponding base group 1, and other conditions are the same as those of base group 1. [Adjustment group 13]

[0183] Based on base group 1, an adaptation group 13 was formed. Adaptation group 13 requires only 10 lithium-ion batteries, and the difference from base group 1 lies in the charging procedures. During the constant current phase, charging is no longer performed with a constant current, but rather in a staggered and distributed manner with high and low currents. The specific procedure is as follows: charging at a rate of 1C for 2 minutes, then stopping charging for 0.1 minutes, then recharging at a rate of 1C for 2 minutes, alternating until the charging cutoff voltage is reached and constant voltage charging is activated. Using this high- and low-current charging procedure, the lithium-ion batteries in each of adaptation groups 13 are, according to 3...000 cycles in gas evolution reduced compared to the corresponding lithium-ion batteries in the corresponding base group 1, and other conditions are the same as those of base group 1.

[0184] Based on adaptation group 11, 12, and 13, the inventor has combined a further charging method for reducing gas evolution, comprising a constant current phase and a constant voltage phase. During the constant current phase, the charging process comprises the following steps: charging within a first period with a first current; charging within a second period with a second current; charging within a third period with a third current; charging within a fourth period with a fourth current; wherein the first current is greater than the second current, the first period being longer than the second period; wherein the third current is not greater than the first current, the third period being longer than the second period; wherein the fourth current is less than the third current, and the fourth period being shorter than the third period.The second current can be 0; it is further preferred that the second current be equal to the fourth current. [Base group 2 to base group 12]

[0185] Based on base group 1, a base group 2 was formed. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 100 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.01479 mmol / Ah (millimoles per ampere-hour) and 0.02285 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.01479 mmol / Ah (millimoles per ampere-hour) and 0.02285 mmol / Ah, the result is 0.11 cm.3 / Ah ≤ v / L ≤ 0.17 cm 3 / Ah, i.e. 0.11 L ≤ v ≤ 0.17 L, where v is given in cubic centimeters (cm³). 3 ).

[0186] Based on base group 1, a base group 3 was formed. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 200 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.01882 mmol / Ah (millimoles per ampere-hour) and 0.02689 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.01882 mmol / Ah (millimoles per ampere-hour) and 0.02689 mmol / Ah, the result is 0.14 cm. 3 / Ah ≤ v / L ≤ 0.2 cm 3 / Ah, i.e. 0.14 L ≤ v ≤ 0.2 L, where v is given in cubic centimeters (cm³). 3 ).

[0187] Based on base group 1, base group 4 was formed. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 400 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.03226 mmol / Ah (millimoles per ampere-hour) and 0.04571 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.03226 mmol / Ah (millimoles per ampere-hour) and 0.04571 mmol / Ah, the result is 0.24 cm. 3 / Ah ≤ v / L ≤ 0.34 cm3 / Ah, i.e. 0.24 L ≤ v ≤ 0.34 L, where v is given in cubic centimeters (cm³). 3 ).

[0188] Based on base group 1, base group 5 was created. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 500 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.03899 mmol / Ah (millimoles per ampere-hour) and 0.05377 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.03899 mmol / Ah (millimoles per ampere-hour) and 0.05377 mmol / Ah, the result is 0.29 cm. 3 / / Ah ≤ v / L ≤ 0.4 cm 3 / Ah, i.e. 0.29 L ≤ v ≤ 0.4 L, where v is given in cubic centimeters (cm³). 3 ).

[0189] Based on base group 1, base group 6 was created. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 600 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.04436 mmol / Ah (millimoles per ampere-hour) and 0.06318 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.04436 mmol / Ah (millimoles per ampere-hour) and 0.06318 mmol / Ah, the result is 0.33 cm. 3 / / Ah ≤ v / L ≤ 0.47 cm 3 / Ah, i.e. 0.33 L ≤ v ≤ 0.47 L, where v is given in cubic centimeters (cm³). 3 ).

[0190] Based on base group 1, base group 7 was created. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 700 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.05109 mmol / Ah (millimoles per ampere-hour) and 0.07259 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.05109 mmol / Ah (millimoles per ampere-hour) and 0.07259 mmol / Ah, the result is 0.38 cm. 3 / Ah ≤ v / L ≤ 0.54 cm 3 / Ah, i.e. 0.38 L ≤ v ≤ 0.54 L, where v is given in cubic centimeters (cm³). 3 ).

[0191] Based on base group 1, base group 8 was created. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 800 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.05915 mmol / Ah (millimoles per ampere-hour) and 0.08738 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.05915 mmol / Ah (millimoles per ampere-hour) and 0.08738 mmol / Ah, the result is 0.44 cm. 3 / Ah ≤ v / L ≤ 0.65 cm 3 / Ah, i.e. 0.44 L ≤ v ≤ 0.65 L, where v is given in cubic centimeters (cm³). 3 ).

[0192] Based on base group 1, base group 9 was created. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 900 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.06856 mmol / Ah (millimoles per ampere-hour) and 0.09545 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.06856 mmol / Ah (millimoles per ampere-hour) and 0.09545 mmol / Ah, the result is 0.51 cm. 3 / Ah ≤ v / L ≤ 0.71 cm 3 / Ah, i.e. 0.51 L ≤ v ≤ 0.71 L, where v is given in cubic centimeters (cm³). 3 ).

[0193] Based on base group 1, base group 10 was created. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 1000 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.07932 mmol / Ah (millimoles per ampere-hour) and 0.10486 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.07932 mmol / Ah (millimoles per ampere-hour) and 0.10486 mmol / Ah, the result is 0.59 cm. 3 / Ah≤v / L ≤ v / L ≤ 0.78 cm 3 / Ah≤v / L, i.e. 0.59 L ≤ v ≤ 0.78 L, where v is given in cubic centimeters (cm³). 3 ).

[0194] Based on base group 1, base group 11 was created. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 1100 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.09141 mmol / Ah (millimoles per ampere-hour) and 0.11696 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is between 0.09141 mmol / Ah (millimoles per ampere-hour) and 0.11696 mmol / Ah, the result is 0.68 cm. 3 / Ah ≤ v / L ≤ 0.87 cm 3 / Ah, i.e. 0.68 L ≤ v ≤ 0.87 L, where v is given in cubic centimeters (cm³). 3 ).

[0195] Based on base group 1, base group 12 was created. The difference from base group 1 is that the capacity of the lithium-ion battery is adjusted to 1200 Ah by reducing the number of cathode and anode foils, while all other conditions remain the same. The ratio of gas evolution N to the capacity L of the lithium-ion battery was ultimately determined to be between 0.1062 mmol / Ah (millimoles per ampere-hour) and 0.13174 mmol / Ah after 3000 cycles. Using the equation Pv = NRT, the ratio of the gas storage volume v to the capacity L of the lithium-ion battery is derived: v / L = NRT / P. Assuming T is 40°C, R is 8.314, the pressure is 0.35 MPa, and N / L is 0.1062 mmol / Ah (millimoles per ampere-hour) to 0.13174 mmol / Ah, the result is 0.79 cm. 3 / Ah ≤ v / L ≤ 0.98 cm 3 / Ah, i.e. 0.79 L ≤ v ≤ 0.98 L, where v is given in cubic centimeters (cm³). 3 ).

[0196] By combining the above adjustment groups and base groups, the inventor further analyzed that the ratio of gas evolution to capacity in lithium-ion batteries increases with increasing capacity. To provide design guidelines for the theoretical gas storage space for lithium-ion batteries with different capacities, the inventor established different design guidelines for batteries with different capacities L for safety reasons. For lithium-ion batteries with capacities below 200 Ah, consideration of the theoretical gas storage space is not necessary. During the assembly of the electrical core, the electrode tabs are welded to the electrode pile, and since the width of the electrode tabs is less than the width of the electrode foil, a certain amount of free space inevitably arises around the electrode tabs due to the assembly process of the electrical core.This inherent clearance is typically about 35 cm. 3 Since the maximum gas evolution for the second base group is 17 cm 3 and for the third base group 40 cm 3 Since the mounting space around the electrode tabs in lithium-ion batteries under 200 Ah is generally sufficient for gas accumulation, this application focuses primarily on lithium-ion batteries of 200 Ah and above, where the theoretical gas storage space plays a more significant role.

[0197] For the electrical core of 200 Ah or more: To increase safety and improve capacity for high-temperature anomalies, it is necessary to increase the standard gas storage volume. Specifically, for lithium-ion batteries with a capacity of 200 Ah ≤ L ≤ 300 Ah, the actual gas storage volume must not be smaller than the lower limit of 0.24 cm³. 3 / Ah of the ratio of the gas storage volume v to the capacity L of the lithium-ion batteries of base group 4. In particular, the lower limit of 0.24 cm 3 / Ah of the ratio of the gas storage space v to the capacity L of the lithium-ion battery of base group 4 is used to calculate the theoretical gas storage space;

[0198] To further reduce the problems caused by gas evolution, it is also preferred that the actual gas storage space not be smaller than the upper limit of 0.34 cm³. 3 The ratio of the gas storage volume v to the capacity L of the lithium-ion battery of base group 4 is 0.34 cm³. 3 The ratio of the gas storage volume v to the capacity L of the base group 4 lithium-ion battery is used to calculate the theoretical gas storage volume;

[0199] To take into account the energy density of the lithium-ion battery, a lower limit of 0.24 cm³ was used to calculate the theoretical gas storage volume. 3 The ratio of the gas storage volume v to the capacity L of the base group 4 lithium-ion battery is used. It is further preferred that the actual gas storage volume is also no larger than the upper limit of 0.34 cm³. 3 / Ah of the ratio of the gas storage volume v to the capacity L of the lithium-ion battery of base group 4. The upper limit of 0.34 cm 3 The ratio of the gas storage volume v to the capacity L of the base group 4 lithium-ion battery is used to calculate the theoretical maximum gas storage volume.

[0200] The same applies to lithium-ion batteries with a capacity of 300 Ah ≤ L ≤ 400 Ah: The actual gas storage volume is no smaller than the lower limit of 0.29 cm³. 3The ratio of the gas storage volume v to the capacity L of the lithium-ion battery of base group 5 is given by / Ah. In particular, the lower limit is 0.29 cm. 3 / Ah of the ratio of the gas storage space v to the capacity L of the lithium-ion battery of base group 5 is used to calculate the theoretical gas storage space;

[0201] It is further preferred that the actual gas storage space should not be smaller than the upper limit of 0.4 cm³. 3 The ratio of the gas storage volume v to the capacity L of the lithium-ion battery of base group 5 is / Ah. The upper limit is 0.4 cm. 3 The ratio of the gas storage volume v to the capacity L of the base group 4 lithium-ion battery is used to calculate the theoretical gas storage volume;

[0202] To take into account the energy density of the lithium-ion battery, a lower limit of 0.29 cm³ was used to calculate the theoretical gas storage volume. 3The ratio of the gas storage volume v to the capacity L of the base group 5 lithium-ion battery is used. It is further preferred that the actual gas storage volume is also no larger than the upper limit of 0.4 cm³. 3 / Ah of the ratio of the gas storage volume v to the capacity L of the lithium-ion battery of base group 5. The upper limit of 0.4 cm 3 The ratio of the gas storage volume v to the capacity L of the base group 5 lithium-ion battery is used to calculate the theoretical maximum gas storage volume.

[0203] Similar designs should be created for the other capacity range. In particular: 1) If the capacity L of the lithium-ion battery is L ≥ 200Ah, preferably 200Ah ≤ L ≤ 300Ah, the corresponding theoretical gas storage volume V0 = 0.24 cm³ 3 / Ah·L in cm 3The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.24 cm³. 3 / Ah·L. For example, if the capacity L of the lithium-ion battery is 200Ah, then the theoretical gas storage volume is 0.24 cm³. 3 / Ah-200Ah = 48 cm 3 For the lithium-ion battery with a capacity L ≥ 200 Ah, preferably 200 Ah ≤ L ≤ 300 Ah, the actual gas storage volume v ≥ 48 cm³ 3 .

[0204] To further reduce the problems caused by gas evolution, it is also preferred that the corresponding theoretical gas storage volume V0=0.34 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.34 cm³. 3 / Ah·L. For example, if the capacity L of the lithium-ion battery is 200Ah, then the theoretical gas storage volume at this time is 0.34 cm³. 3 / Ah-200Ah = 68 cm 3 .

[0205] To account for the energy density of the lithium-ion battery, the theoretical maximum gas storage volume VOmax = 0.34 cm³ 3 / Ah·L in cm 3 Then the actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.24 cm³. 3 / Ah·L, and at the same time the actual gas storage volume v should be less than or equal to the theoretical maximum gas storage volume V0max=0.34 cm³ 3 / Ah·L. If the capacity of the lithium-ion battery L is 200Ah, the theoretical maximum gas storage volume at this time is 68 cm³. 3 .

[0206] 2) If the capacity L of the lithium-ion battery is 300Ah < L ≤ 400 Ah, the corresponding theoretical gas storage volume V0 = 0.29 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.29 cm³. 3 / Ah·L. For example, if L > 300Ah, then the theoretical gas storage volume V0 > 0.29 cm³. 3 / Ah-300Ah = 87 cm 3 If the capacity L of the lithium-ion battery is 300Ah<L≤400Ah beträgt, beträgt der tatsächliche Gasspeicherraum v > 87cm 3 .

[0207] To further reduce the problems caused by gas evolution, it is also preferred that the corresponding theoretical gas storage volume V0=0.4 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.4 cm³. 3 / Ah·L be.

[0208] To account for the energy density of the lithium-ion battery, the theoretical maximum gas storage volume VOmax = 0.4 cm³ 3 / Ah·L in cm 3 Then the actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.29 cm³. 3 / Ah·L, and at the same time the actual gas storage volume v should be less than or equal to the theoretical maximum gas storage volume V0max=0.4 cm³ 3 / Ah·L be.

[0209] 3) If the capacity L of the lithium-ion battery is 400 Ah < L ≤ 500 Ah, the corresponding theoretical gas storage volume V0 = 0.33 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.33 cm³. 3 / Ah·L. To further reduce the problems caused by gas evolution, it is also preferred that the corresponding theoretical gas storage volume V0=0.47 cm³. 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.47 cm³. 3 / Ah·L be.

[0210] To account for the energy density of the lithium-ion battery, the theoretical maximum gas storage volume VOmax = 0.47 cm³ 3 / Ah·L in cm 3 Then the actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.33 cm³. 3 / Ah·L, and at the same time the actual gas storage volume v should be less than or equal to the theoretical maximum gas storage volume V0max=0.47 cm³ 3 / Ah·L be.

[0211] If the capacity L of the lithium-ion battery is 300Ah < L ≤ 500Ah, it is understandable that in combination with 2) and 3) the actual gas storage volume v > 87 cm³ 3 is.

[0212] 4) If the capacity L of the lithium-ion battery is 500Ah < L ≤ 600Ah, the corresponding theoretical gas storage volume V0 = 0.38 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.38 cm³.3 / Ah·L. For example, if L > 500Ah, the theoretical gas storage volume V0 is 0.38 cm³. 3 / Ah-500Ah = 190 cm 3 If the capacity L of the lithium-ion battery is 500Ah < L ≤ 600Ah, the actual gas storage volume v is > 190 cm³. 3 .

[0213] To further reduce the problems caused by gas evolution, it is also preferred that the corresponding theoretical gas storage volume V0=0.54cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.54 cm³. 3 / Ah·L be.

[0214] To account for the energy density of the lithium-ion battery, the theoretical maximum gas storage volume VOmax = 0.54 cm³ 3 / Ah·L in cm 3 Then the actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.38cm³. 3 / Ah·L, and at the same time the actual gas storage volume v should be less than or equal to the theoretical maximum gas storage volume Vomax=0.54cm 3 / Ah·L be.

[0215] 5) If the capacity L of the lithium-ion battery is 600 Ah < L ≤ 700 Ah, the corresponding theoretical gas storage volume V0 = 0.44 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.44 cm³. 3 / Ah·L. To further reduce the problems caused by gas evolution, it is also preferred that the corresponding theoretical gas storage volume V0=0.65 cm³. 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.65 cm³. 3 / Ah·L be.

[0216] To account for the energy density of the lithium-ion battery, the theoretical maximum gas storage volume VOmax = 0.65 cm³ 3 / Ah·L in cm 3 Then the actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.44 cm³. 3 / Ah·L, and at the same time the actual gas storage volume v should be less than or equal to the theoretical maximum gas storage volume Vomax=0.65cm 3 / Ah·L be.

[0217] If the capacity L of the lithium-ion battery is 500Ah < L ≤ 700Ah, it is understandable that in combination with 4) and 5) the actual gas storage volume v > 190 cm³ 3 is.

[0218] 6) If the capacity L of the lithium-ion battery is 700 Ah < L ≤ 800 Ah, the corresponding theoretical gas storage volume V0 = 0.51 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.51 cm³.3 / Ah·L. To further reduce the problems caused by gas evolution, it is also preferred that the corresponding theoretical gas storage volume V0=0.71 cm³. 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.71 cm³. 3 / Ah·L be.

[0219] To account for the energy density of the lithium-ion battery, the theoretical maximum gas storage volume VOmax = 0.71 cm³ 3 / Ah·L in cm 3 Then the actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.51 cm³. 3 / Ah·L, and at the same time the actual gas storage volume v should be less than or equal to the theoretical maximum gas storage volume V0max=0.71 cm³ 3 / Ah·L be.

[0220] 7) If the capacity L of the lithium-ion battery is 800 Ah < L ≤ 900 Ah, the corresponding theoretical gas storage volume V0 = 0.59 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.59 cm³. 3 / Ah·L. To further reduce the problems caused by gas evolution, it is also preferred that the corresponding theoretical gas storage volume V0=0.78 cm³. 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.78 cm³. 3 / Ah·L be.

[0221] To account for the energy density of the lithium-ion battery, the theoretical maximum gas storage volume VOmax = 0.78 cm³ 3 / Ah·L in cm 3 Then the actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.59 cm³. 3 / Ah·L, and at the same time the actual gas storage volume v should be less than or equal to the theoretical maximum gas storage volume V0max=0.78 cm³ 3 / Ah·L be.

[0222] 8) If the capacity L of the lithium-ion battery is 900 Ah < L ≤ 1000 Ah, the corresponding theoretical gas storage volume V0 = 0.68 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.68 cm³. 3 / Ah·L. To further reduce the problems caused by gas evolution, it is also preferred that the corresponding theoretical gas storage volume V0=0.87 cm³. 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.87 cm³. 3 / Ah·L be.

[0223] To account for the energy density of the lithium-ion battery, the theoretical maximum gas storage volume VOmax = 0.87 cm³ 3 / Ah·L in cm 3 Then the actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.68 cm³. 3 / Ah·L, and at the same time the actual gas storage volume v should be less than or equal to the theoretical maximum gas storage volume V0max=0.87 cm³ 3 / Ah·L be.

[0224] 9) If the capacity L of the lithium-ion battery is 1000 Ah < L ≤ 1100 Ah, the corresponding theoretical gas storage volume V0 = 0.79 cm³ 3 / Ah·L in cm 3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.79 cm³. 3 / Ah·L. To further reduce the problems caused by gas evolution, it is also preferred that the corresponding theoretical gas storage volume V0=0.98 cm³. 3 / Ah·L in cm3 The actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0 = 0.98 cm³. 3 / Ah·L be.

[0225] To account for the energy density of the lithium-ion battery, the theoretical maximum gas storage volume VOmax = 0.98 cm³ 3 / Ah·L in cm 3 Then the actual gas storage volume v should be greater than or equal to the theoretical gas storage volume V0=0.79 cm³. 3 / Ah·L, and at the same time the actual gas storage volume v should be less than or equal to the theoretical maximum gas storage volume V0max=0.98 cm³ 3 / Ah·L be.

[0226] In the practical design of lithium-ion batteries, the theoretical gas storage volume V0 and the theoretical maximum gas storage volume VOmax can be calculated based on the preset capacity L of the lithium-ion batteries. The actual gas storage volume v, reserved within the battery casing, should therefore be greater than or equal to the theoretical gas storage volume V0. To optimize energy density, it is advantageous for the actual gas storage volume v to be less than or equal to the theoretical maximum gas storage volume VOmax.

[0227] For the actual gas storage space, other components between the casing and the electrical core, such as the support structure, are excluded. These components also occupy volume.

[0228] The above base groups and adaptation groups are exemplary, serve to explain the present application and cannot be understood as a restriction on the present application.

[0229] Exemplary embodiment 1: The difference to basic group 1 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 72 cm³. 3This corresponds to the design and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the process is cycled for 3000 cycles.

[0230] Example 2: The difference to base group 3 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 48 cm³. 3This corresponds to the design and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the process is cycled for 3000 cycles.

[0231] Exemplary embodiment 3: The difference to base group 11 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 869 cm³. 3This corresponds to the design and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the process is cycled for 3000 cycles.

[0232] Exemplary embodiment 4: The difference to basic group 4 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 116 cm³. 3This corresponds to the design and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the process is cycled for 3000 cycles.

[0233] Exemplary embodiment 5: The difference to basic group 5 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 165 cm³. 3This corresponds to the design and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the process is cycled for 3000 cycles.

[0234] Exemplary embodiment 6: The difference to basic group 6 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 228 cm³. 3This corresponds to the fact that there is no gas pressure sensor inside the sixth housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles.

[0235] Exemplary embodiment 7: The difference to basic group 7 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 308 cm³. 3This corresponds to the design and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the process is cycled for 3000 cycles.

[0236] Exemplary embodiment 8: The difference to basic group 8 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 408 cm³. 3This corresponds to the fact that there is no gas pressure sensor inside the sixth housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles.

[0237] Example 9: The difference to base group 9 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 531 cm³. 3This corresponds to the design and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the process is cycled for 3000 cycles.

[0238] Exemplary embodiment 10: The difference to basic group 10 is that the gas storage space of the lithium-ion battery corresponds to the theoretical gas storage space of 680 cm³. 3This corresponds to the fact that there is no gas pressure sensor inside the sixth housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles.

[0239] Comparative example 1: The difference to base group 1 is that the gas storage space of the lithium-ion battery is 54 cm³. 3 (The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.18 cm³) 3 Ah, which is smaller than the lower limit of 0.19 cm 3 / Ah of base group 1) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the cycle is repeated for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0240] Comparative example 2: The difference to base group 3 is that the gas storage space of the lithium-ion battery is 26 cm³. 3(The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.13 cm³) 3 Ah, which is smaller than the lower limit of 0.14 cm 3 / Ah of base group 3) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0241] Comparative example 3: The difference to base group 11 is that the gas storage space of the lithium-ion battery is 737 cm³. 3 (The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.67 cm³) 3 Ah, which is smaller than the lower limit of 0.68 cm 3 / Ah of base group 11) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cut-off voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0242] Comparative example 4: The difference to base group 4 is that the gas storage space of the lithium-ion battery is 92 cm³. 3(The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.23 cm³) 3 Ah, which is smaller than the lower limit of 0.24 cm 3 / Ah of base group 4) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the cycle is repeated for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0243] Comparative example 5: The difference to base group 5 is that the gas storage space of the lithium-ion battery is 140 cm³. 3 (The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.28 cm³) 3 Ah, which is smaller than the lower limit of 0.29 cm 3 / Ah of base group 5) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cut-off voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0244] Comparative example 6: The difference to base group 6 is that the gas storage space of the lithium-ion battery is equal to the theoretical gas storage space of 192 cm³. 3is (the ratio of the gas storage space v of the corresponding lithium-ion battery to the capacity L is 0.32 cm³ 3 Ah, which is smaller than the lower limit of 0.33 cm 3 / Ah of base group 6) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0245] Comparative example 7: The difference to base group 7 is that the gas storage space of the lithium-ion battery is equal to the theoretical gas storage space of 259 cm³. 3 is (the ratio of the gas storage space v of the corresponding lithium-ion battery to the capacity L is 0.37cm 3 Ah, which is smaller than the lower limit of 0.38 cm 3 / Ah of base group 7) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0246] Comparative example 8: The difference to base group 8 is that the gas storage space of the lithium-ion battery is 344 cm³. 3(The ratio of the gas storage space v of the corresponding lithium-ion battery to the capacity L is 0.43 cm³) 3 Ah, which is smaller than the lower limit of 0.44 cm 3 / Ah of base group 8) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0247] Comparative example 9: The difference to base group 9 is that the gas storage space of the lithium-ion battery is 450 cm³. 3 (The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.50 cm³) 3 Ah, which is smaller than the lower limit of 0.51 cm 3 / Ah of base group 9) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0248] Comparative example 10: The difference to base group 10 is that the gas storage space of the lithium-ion battery is 580 cm³. 3(The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.58 cm³) 3 Ah, which is smaller than the lower limit of 0.59 cm 3 / Ah of base group 10) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0249] Comparative example 11: The difference to base group 1 is that the gas storage space of the lithium-ion battery is 66 cm³. 3 (The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.22 cm³) 3 Ah, something smaller than the upper limit of 0.26 cm 3 / Ah of base group 1) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the cycle is repeated for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0250] Comparative example 12: The difference to base group 3 is that the gas storage space of the lithium-ion battery is 36 cm³. 3(The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.18 cm³) 3 Ah, something smaller than the upper limit of 0.2 cm 3 / Ah of base group 3) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0251] Comparative example 13: The difference to base group 11 is that the gas storage space of the lithium-ion battery is 836 cm³. 3 (The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.76 cm³) 3 Ah, which is smaller than the upper limit of 0.87 cm 3 / Ah of base group 11) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cut-off voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0252] Comparative example 14: The difference to base group 4 is that the gas storage space of the lithium-ion battery is 114 cm³. 3(The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.28 cm³) 3 Ah, something smaller than the upper limit of 0.34 cm 3 / Ah of base group 4) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C. The other conditions are the same as for the 50 lithium-ion batteries of the first part, and the cycle is repeated for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0253] Comparative example 15: The difference to base group 5 is that the gas storage space of the lithium-ion battery is 155 cm³. 3 (The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.31 cm³) 3 Ah, something smaller than the upper limit of 0.4 cm 3 / Ah of base group 5) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cut-off voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0254] Comparative example 16: The difference to base group 6 is that the gas storage space of the lithium-ion battery is 216 cm³. 3(The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.36 cm³) 3 Ah, something smaller than the upper limit of 0.47 cm 3 / Ah of base group 6) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0255] Comparative example 17: The difference to base group 7 is that the gas storage space of the lithium-ion battery is 294 cm³. 3 (The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.42 cm³) 3 Ah, something smaller than the upper limit of 0.54 cm 3 / Ah of base group 7) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0256] Comparative example 18: The difference to base group 8 is that the gas storage space of the lithium-ion battery is 392 cm³. 3(The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.49 cm³) 3 Ah, something smaller than the upper limit of 0.65 cm 3 / Ah of base group 8) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0257] Comparative example 19: The difference to base group 9 is that the gas storage space of the lithium-ion battery is 513 cm³. 3 (The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.57 cm³) 3 Ah, something smaller than the upper limit of 0.71 cm 3 / Ah of base group 9) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0258] Comparative example 20: The difference to base group 10 is that the gas storage space of the lithium-ion battery is 660cm³. 3(The ratio of the gas storage volume v of the corresponding lithium-ion battery to the capacity L is 0.66 cm³) 3 Ah, something smaller than the upper limit of 0.78 cm 3 / Ah of base group 10) and no gas pressure sensor is located inside the housing. Furthermore, the 50 lithium-ion batteries of the first part of this embodiment are cycled for 3000 cycles at 40°C. After the 50 lithium-ion batteries of the second part of this embodiment have been cycled for 1500 cycles at 40°C, each subsequent charging process proceeds as follows: Before charging to the cutoff voltage, a 3-minute cycle at 90°C is added to the charging process at 40°C; the other conditions are the same as for the 50 lithium-ion batteries of the first part, and it is cycled for 3000 cycles (terminating the charging and discharging process when the explosion protection valve of a lithium-ion battery is opened).

[0259] Comparison 21: The difference to base group 1 lies in the use of lithium nickel cobalt manganese oxide with a nickel to total nickel, cobalt, and manganese atomic ratio of 0.8 as the active cathode material, as well as corresponding adjustments to the charging and discharging cutoff voltages, the thickness, and the density of the cathode foil. The remaining conditions correspond to those of base group 1.

[0260] In embodiments 1 to 10, none of the explosion protection valves were opened after 3000 cycles of the lithium-ion battery.

[0261] In comparison examples 1 to 10, none of the lithium-ion batteries were opened in the first part of each comparison example, while 15 to 25 lithium-ion batteries were opened in the second part of each comparison example.

[0262] In comparative examples 11 to 20, none of the lithium-ion batteries in the first part of each comparative example were opened, while 1 to 10 lithium-ion batteries in the second part of each comparative example were opened.

[0263] In comparative example 21, 70 lithium-ion cells were opened.

[0264] Comparative Example 21 and Exemplary Depiction 1 show that the selection of the material system, in particular the choice of cathode material, has a significant influence on the opening of the explosion protection valve. From the perspective of gas evolution, lithium-containing phosphate is preferable.

[0265] Examples 1 to 10, Comparative Examples 1 to 10, and Comparative Examples 11 to 20 demonstrate that lithium-ion batteries, during normal operation, not only remain open when the actual gas storage volume is not smaller than the theoretical gas storage volume, but also possess the ability to withstand high temperature anomalies, thereby increasing the safety of lithium-ion batteries. Comparative Examples 1 to 10 and Comparative Examples 11 to 20 show that while the actual gas storage volume is smaller than the theoretical gas storage volume, the closer it is to the theoretical gas storage volume, the greater the ability to withstand high temperature anomalies.

[0266] The present application comprehensively addresses the reduction of gas evolution by considering several factors, including the active cathode material, the active anode material, the cathode foil, the anode foil, the separator, and the electrolyte solution, thereby minimizing unnecessary internal space. This allows for an increased active material loading, thus improving the capacity of the lithium-ion battery. Simultaneously, the gas storage space is optimized based on the aforementioned measures for reducing gas evolution. As a result, the lithium-ion battery of the present application can prevent the explosion protection valve from opening under normal operating conditions while maintaining resistance to high-temperature anomalies. Consequently, the risk of lithium-ion battery failure due to explosion protection valve activation is reduced.

[0267] It should be noted that the present application is not limited to the embodiments mentioned above. The embodiments mentioned above are only examples, and embodiments within the scope of the technical solution of the present application that have essentially the same composition as the technical idea and have the same effect are included in the technical scope of the present application. Furthermore, within the scope of the present application, other possibilities for constructing the embodiments by combining some of the constituent elements of the embodiments and applying various deformations to the embodiments that a person skilled in the art can imagine without departing from the subject matter of the present application are also included. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Lithium-ion battery, charging method and lithium-ion battery system”, published on September 26, 2024

[0001]

Claims

[1] Lithium-ion battery comprising a casing, an electrical core and an electrolyte solution, wherein the electrical core and the electrolyte solution are arranged inside the casing, wherein the electrical core comprises a cathode foil, an anode foil and a separator, the separator being arranged between the cathode foil and the anode foil, the cathode foil comprising a cathode collector and an active cathode substance layer, the active cathode substance layer being electrically connected to the cathode collector; wherein the anode foil comprises an anode collector and an active anode substance layer, the active anode substance layer being electrically connected to the anode collector; characterized bythat the anode collector is provided with the active anode substance layer on at least one surface, wherein the thickness of the one-sided active anode substance layer of the anode foil is 50 µm to 95 µm; wherein the active anode substance layer comprises an active anode substance, the active anode substance comprising graphite; wherein Dv50 of the graphite is in a range of 10 µm to 30 µm, wherein the degree of graphitization of the graphite is greater than or equal to 90%; and that the cathode collector is provided with the active cathode substance layer on at least one surface, wherein the thickness of the one-sided active cathode substance layer of the cathode foil is 60 µm to 105 µm; wherein the active cathode substance layer comprises an active cathode substance, wherein the active cathode substance is a lithium-containing phosphate and a carbon layer located on the surface of the lithium-containing phosphate; where the capacity L of the lithium-ion battery is 500Ah < L ≤ 700Ah, and where the actual gas storage volume v of the lithium-ion battery is greater than 190 cm³ 3 is. [2] Lithium-ion battery according to claim 1, characterized by , that, The capacity L of the lithium-ion battery is 500Ah < L ≤ 600Ah, where the theoretical gas storage volume of the lithium-ion battery is V0, where V0=0.38 cm³ 3 / Ah·L; or, that the capacity L of the lithium-ion battery is 600Ah < L ≤ 700Ah, where the theoretical gas storage volume of the lithium-ion battery is V0, where V0 = 0.44 cm³ 3 / / Ah·L; where the actual gas storage volume v of the lithium-ion battery is larger than the theoretical gas storage volume of the lithium-ion battery V0. [3] Lithium-ion battery according to claim 1, characterized by , that, The capacity L of the lithium-ion battery is 500Ah < L ≤ 600Ah, where the theoretical gas storage volume of the lithium-ion battery is V0, where V0=0.54 cm³ 3 / Ah·L; or, that the capacity L of the lithium-ion battery is 600Ah < L ≤ 700Ah, where the theoretical gas storage volume of the lithium-ion battery is V0, where V0 = 0.65 cm³ 3 / Ah·L; where the actual gas storage volume v of the lithium-ion battery is larger than the theoretical gas storage volume of the lithium-ion battery V0. [4] Lithium-ion battery according to claim 2, characterized by , that, The capacity L of the lithium-ion battery is 500Ah < L ≤ 600Ah, where the theoretical maximum gas storage volume of the lithium-ion battery is VOmax, where V0max=0.54 cm³ 3 / Ah·L; or, that the capacity L of the lithium-ion battery is 600Ah < L ≤ 700Ah, where the theoretical maximum gas storage volume of the lithium-ion battery is VOmax, where V0max = 0.65 cm³ 3 / Ah·L; where the actual gas storage volume v of the lithium-ion battery is less than or equal to the theoretical gas storage volume of the lithium-ion battery VOmax. [5] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that at least part of the surface of the graphite is coated with a carbon layer, wherein Dv90 of the graphite is less than or equal to 40 µm, wherein Dv10 of the graphite is greater than or equal to 3 µm, and wherein Dv99 of the graphite is less than or equal to 49 µm; and / or that, the OI value of the graphite is in a range of 3 to 30; and / or, that the degree of graphitization of the graphite is between 90% and 95%. [6] Lithium-ion battery according to claim 5, characterized by, that the OI value of the graphite is in a range of 10 to 30. [7] Lithium-ion battery according to claim 5, characterized by , that the degree of graphitization of the graphite is between 91% and 95%; and / or, that the OI value of the graphite is in a range of 15 to 30. [8] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the areal density of the one-sided active substance layer of the anode foil is between 0.07 mg / mm² 2 up to 0.13 mg / mm 2 amounts. [9] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the density of the one-sided active substance layer of the anode foil is between 1.3 g / cc and 1.7 g / cc. [10] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the areal density of the one-sided active substance layer of the cathode foil is between 0.16 mg / mm² 2 up to 0.26 mg / mm 2 amounts. [11] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the density of the one-sided active substance layer of the cathode foil is between 2.3 g / cc and 2.7 g / cc. [12] Lithium-ion battery according to any one of claims 1 to 4, characterized by that the separator comprises a base film and a coating, wherein the coating is bonded to the surface of the base film and is partially located within the base film, wherein the porosity of the separator is between 30% and 50%. [13] Lithium-ion battery according to claim 5, characterized by , that the thickness of the carbon layer on the surface of the graphite is between 0.5 µm and 2 µm. [14] Lithium-ion battery according to any one of claims 1 to 4, characterized by, that the active anode material layer further comprises a carbon tube; and / or, that the active anode material layer further comprises silicon, wherein the mass content of silicon in the active anode material layer is between 1% and 8%. [15] Lithium-ion battery according to claim 14, characterized by , that the carbon tube comprises at least one oligo-walled carbon tube and one single-walled carbon tube. [16] Lithium-ion battery according to claim 14, characterized by , that the silicon is distributed in the thickness direction of the active anode material layer on a side facing the anode collector in the active anode material layer. [17] Lithium-ion battery according to any one of claims 1 to 4, characterized by, that the lithium-containing phosphate comprises lithium iron phosphate, wherein the lithium iron phosphate is doped with a metal element, the metal element being selected from at least one of the elements titanium or vanadium. [18] Lithium-ion battery according to claim 17, characterized by that the mass fraction of the doped metal element in the active cathode substance does not exceed 0.4%. [19] Lithium-ion battery according to claim 18, characterized by , that the doped metallic element comprises titanium, wherein the mass fraction of titanium in the active cathode substance is 0.2% to 0.4%. [20] Lithium-ion battery according to claim 18, characterized by , that the doped metallic element comprises titanium and vanadium, wherein the mass fraction of titanium in the active cathode substance is 0.1% to 0.2%, and wherein the mass fraction of vanadium in the active cathode substance is 0.01% to 0.05%. [21] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the active cathode substance layer comprises a carbon tube, wherein the carbon tube comprises at least one of an oligo-walled carbon tube and a single-walled carbon tube. [22] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the electrolyte solution comprises a lithium salt and a solvent, wherein the molar volume content of the lithium salt is 0.8 mol / L to 1.5 mol / L, and wherein the lithium salt comprises lithium hexafluorophosphate. [23] Lithium-ion battery according to claim 22, characterized by , that the lithium salt further comprises lithium bis(fluorosulfonyl)imide. [24] Lithium-ion battery according to claim 23, characterized by , that the molar volume content of lithium hexafluorophosphate is higher than the molar volume content of lithium bis(fluorosulfonyl)imide. [25] Lithium-ion battery according to claim 24, characterized by, that the mass fraction of lithium bis(fluorosulfonyl)imide in the electrolyte solution is between 3% and 9%. [26] Lithium-ion battery according to claim 23, characterized by , that the solvent comprises EC, DMC, EMC, DEC; wherein the content of EC is between 30% and 40%, wherein the sum of the masses of DMC and EMC is greater than the mass of EC; wherein the content of EC is equal to the mass of EC / (the difference between the mass of the electrolyte solution and the mass of the lithium salt). [27] Lithium-ion battery according to claim 26, characterized by , that the total content of EMC and DMC is in the range of 50% to 60%; where the total content of EMC and DMC is equal to the total mass of EMC and DMC / (the difference between the mass of the electrolyte solution and the mass of the lithium salt). [28] Lithium-ion battery according to claim 27, characterized by, that the DMC content is in the range of 10% to 15%; where the DMC content is equal to the mass of DMC / (the difference between the mass of the electrolyte solution and the mass of the lithium salt). [29] Lithium-ion battery according to claim 23, characterized by , that the electrolyte solution further comprises a carboxylic acid ester, wherein the content of the carboxylic acid ester is not more than 10%; wherein the content of the carboxylic acid ester is equal to the mass of the carboxylic acid ester / (the difference between the mass of the electrolyte solution and the mass of the lithium salt). [30] Lithium-ion battery according to any one of claims 23 to 29, characterized by that the anode foil has a square structure, with the width of the anode foil being between 100 mm and 150 mm, with the porosity of the separator being in the range of 30% to 50%. [31] Lithium-ion battery according to any one of claims 23 to 29, characterized by, that the anode foil has a square structure, with the width of the anode foil being between 200 mm and 250 mm, with the porosity of the separator being in the range of 35% to 50%. [32] Lithium-ion battery according to claim 30, characterized by , that the length-to-width ratio of the electrical core is between 6 and 8. [33] Lithium-ion battery according to claim 31, characterized by , that the length-to-width ratio of the electric core is between 2.8 and 4. [34] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the anode foil further comprises an anode tab, wherein the anode tab is electrically connected to the anode collector, and that the cathode foil further comprises a cathode tab, wherein the cathode tab is electrically connected to the cathode collector; wherein the housing comprises a cathode column, an anode column and an explosion protection valve, wherein the cathode column is electrically connected to the cathode tab, while the anode column is electrically connected to the anode tab, wherein the explosion protection valve is arranged at a first end of the housing, wherein at least one of the cathode column and the anode column is arranged at the first end of the housing, wherein the opening air pressure of the explosion protection valve is 0.55 MPa to 0.65 MPa, wherein the ratio of the area of ​​the explosion protection valve to the capacity of the lithium-ion battery is in the range of 0.5 mm² 2 / Ah up to 1.5 mm 2 Ah, it lies. [35] Lithium-ion battery according to claim 34, characterized by, that the cathode column is arranged at the first end of the housing, and that the cathode tab is arranged on a short edge of the cathode collector; wherein a first upper exhaust channel is formed between the upper end of the cathode tab and the housing, wherein, along the airflow direction of the first upper exhaust channel, the projection area of ​​the explosion protection valve overlaps at least partially with the projection area of ​​the first upper exhaust channel. [36] Lithium-ion battery according to claim 35, characterized by, that along the airflow direction of the first upper exhaust duct the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the first upper exhaust duct is more than 80%; wherein the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the first upper exhaust duct is the ratio of the area of ​​an overlap area between the projection area of ​​the explosion protection valve and the projection area of ​​the first upper exhaust duct to the area of ​​the projection area of ​​the first upper exhaust duct. [37] Lithium-ion battery according to one of claims 35 or 36, characterized by , that the cathode tabs are distributed asymmetrically on the short edge of the cathode collector. [38] Lithium-ion battery according to claim 37, characterized by, that along a width direction of the electrical core the vertical distance from an upper end of the cathode tab to the upper end of the cathode foil is a first distance, wherein the vertical distance from a lower end of the cathode tab to the lower end of the cathode foil is a second distance, wherein the first distance is greater than the second distance. [39] Lithium-ion battery according to claim 34, characterized by , that the anode column is arranged at the first end of the housing, and that the anode tab is arranged on a short edge of the anode collector; wherein a second upper exhaust channel is formed between the upper end of the anode tab and the housing, wherein, along the airflow direction of the second upper exhaust channel, the projection area of ​​the explosion protection valve overlaps at least partially with the projection area of ​​the second upper exhaust channel. [40] Lithium-ion battery according to claim 39, characterized by, that along the airflow direction of the second upper exhaust duct the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the second upper exhaust duct is more than 80%; wherein the degree of overlap between the projection area of ​​the explosion protection valve and the projection area of ​​the second upper exhaust duct is the ratio of the area of ​​an overlap area between the projection area of ​​the explosion protection valve and the projection area of ​​the second upper exhaust duct to the area of ​​the projection area of ​​the second upper exhaust duct. [41] Lithium-ion battery according to claim 39 or 40, characterized by , that the ratio of the width of the anode tab to the width of the short edge of the anode collector is in the range of 0.5 to 0.

8. [42] Lithium-ion battery according to claim 41, characterized by, that the ratio of the width of the anode tab to the width of the short edge of the anode collector is in the range of 0.6 to 0.

8. [43] Lithium-ion battery according to one of claims 39 or 40, characterized by that the anode tabs are distributed asymmetrically on the short edge of the anode collector. [44] Lithium-ion battery according to claim 43, characterized by , that along a width direction of the electrical core the vertical distance from an upper end of the anode tab to the upper end of the anode foil is a third distance, wherein the vertical distance from a lower end of the anode tab to the lower end of the anode foil is a fourth distance, wherein the third distance is greater than the fourth distance. [45] Lithium-ion battery according to any one of claims 1 to 4, characterized by, that the difference between Dv50 and Dv10 of the graphite is less than or equal to 10 µm, and the difference between Dv90 and Dv50 of the graphite is less than or equal to 15 µm. [46] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the cathode collector is an aluminum foil, wherein the thickness of the one-sided active substance layer of the cathode foil is less than or equal to 95 µm, wherein the thickness of the cathode collector is D1, where the value of D1 is in the range of 11 µm to 13.5 µm. [47] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the thickness of the one-sided active substance layer of the cathode foil is greater than 95 µm, wherein the thickness of the cathode collector is D2, where the value of D2 is in the range of 13.5 µm to 16 µm. [48] ​​Lithium-ion battery according to any one of claims 1 to 4, characterized by, that the active anode substance layer further comprises silicon; wherein the thickness of the one-sided active substance layer of the anode foil is in the range of 50 µm to 70 µm, wherein the mass content of the silicon in the active anode substance layer is in the range of 1% to 10%. [49] Lithium-ion battery according to any one of claims 1 to 4, characterized by , that the active anode substance layer further comprises silicon; wherein the thickness of the one-sided active substance layer of the anode foil is in the range of 70 µm to 80 µm, wherein the mass content of the silicon in the active anode substance layer is in the range of 1% to 8%. [50] Lithium-ion battery according to any one of claims 1 to 4, characterized by, that the active anode substance layer further comprises silicon; wherein the thickness of the one-sided active substance layer of the anode foil is in the range of 80 µm to 95 µm, wherein the mass content of the silicon in the active anode substance layer is in the range of 1% to 5%. [51] Lithium-ion battery according to claim 29, characterized by , that the content of the carboxylic acid ester is in the range of 5% to 10%, with the mass fraction of the lithium bis(fluorosulfonyl)imide in the electrolyte solution being between 2% and 7%. [52] Lithium-ion battery according to claim 5, characterized by , that the active anode substance comprises graphite and primary particles formed by the carbon layer on the surface of the graphite, with Dv50 of the primary particles being in the range of 10 µm to 20 µm. [53] Lithium-ion battery according to claim 52, characterized by, that the active anode substance comprises secondary particles, wherein the secondary particles comprise agglomerates of the primary particles, with Dv50 of the secondary particles being in the range of 10 µm to 30 µm. [54] Lithium-ion battery according to claim 53, characterized by that the surface of the agglomerates is coated with the carbon layer. [55] Lithium-ion battery system, characterized by that the system comprises a management module and a lithium-ion battery according to any one of claims 1 to 54, wherein the management module comprises a charging program for the lithium-ion battery.

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