A lithium ion battery and an electric device

Abstract

This application relates to the field of lithium-ion battery technology, and discloses a lithium-ion battery and an electrical device. The lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte. The positive electrode active material in the positive electrode is a high-nickel material, and the mass percentage of aluminum in the high-nickel material is W. A W A The numerical range is 0.01wt%–0.2wt%; the electrolyte includes a sulfur-containing compound H, and the mass percentage of sulfur-containing compound H in the electrolyte is W. K W K The numerical range is 0.1wt%–2wt%; and W A and W K The proportional relationship is satisfied: 0.5 ≤ W K / W A ≤200; and, when the lithium-ion battery is stored at a first target number of days at an ambient temperature T1 with a capacity of Q1, the total amount of gas produced is V1, and the value of V1 ranges from 0.4mL to 3.5mL; when the lithium-ion battery is stored at a second target number of days at an ambient temperature T2 with a capacity of Q1, the growth rate of the AC internal resistance ranges from 15% to 30%.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, specifically to a lithium-ion battery and an electrical device. Background Technology

[0002] Currently, with the widespread application of high-energy-density ternary materials in power and energy storage fields, they pose more severe challenges to the high-temperature performance of batteries. Specifically, under high-temperature cycling and storage conditions, the poor stability of the interface between the ternary cathode material and the conventional electrolyte can trigger violent catalytic oxidation and decomposition reactions, leading to continuous electrolyte consumption and the generation of large amounts of gas, causing battery swelling and a sharp decrease in capacity. This not only severely limits the battery's lifespan but also brings safety hazards such as thermal runaway. Therefore, how to construct a stable cathode / electrolyte interface and effectively suppress high-temperature gas generation has become crucial for promoting the safe application of high-energy-density lithium-ion batteries.

[0003] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art: High-nickel ternary lithium-ion batteries in related technologies are prone to generating a large amount of gas during the cyclic charging and discharging process in high-temperature environments. This often causes the current interrupt device (CID) to brake prematurely, resulting in battery failure.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0006] This disclosure provides a lithium-ion battery and an electrical device to improve the stability between the positive electrode and the electrolyte interface, thereby reducing gas generation during the cyclic charging and discharging process of a high-nickel ternary lithium-ion battery in a high-temperature environment.

[0007] In some embodiments, the lithium-ion battery includes a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode active material in the positive electrode is a high-nickel material, and the mass percentage of aluminum in the high-nickel material is W. A W A The numerical range is 0.01wt%-0.2wt%; the electrolyte includes a sulfur-containing compound H, and the mass percentage of sulfur-containing compound H in the electrolyte is W. K WK The numerical range is 0.1wt%-2wt%; and W A and W K The proportional relationship is satisfied: 0.5 ≤ W K / W A ≤200; and, when the lithium-ion battery is stored at Q1 capacity and ambient temperature T1 for a first target number of days, the total amount of gas generated is V1, and the value of V1 ranges from 0.4mL to 3.5mL; when the lithium-ion battery is stored at Q1 capacity and ambient temperature T2 for a second target number of days, the growth rate of the AC internal resistance ranges from 15% to 30%; Wherein, the ambient temperature T1 satisfies 45℃≤T1≤85℃, the ambient temperature T2 satisfies 45℃≤T2≤60℃, Q1 is the full-charge capacity of a lithium-ion battery in an empty state after being left to stand at 25℃ for 1 hour and then charged to 4.2V at a constant current and constant voltage of 0.5C, and the first target number of days is less than the second target number of days.

[0008] Optionally, the first target number of days is 2 to 4 days, and the second target number of days is 95 to 105 days.

[0009] Optionally, the electrolyte further includes lithium hexafluorophosphate, lithium salt additives, and solvents; wherein, by mass percentage, the lithium hexafluorophosphate accounts for 12%-20%, the sulfur-containing compound H accounts for 0.1%-2%, and the remainder is lithium salt additives and solvents.

[0010] Optionally, the sulfur-containing compound H includes one or more of vinyl sulfate DTD, propylene sulfate TS, vinyl sulfite ES, 1,3-propanediol cyclosulfonate PCS, 1,3-propanesulfonate lactone PS, 1,3-propenesulfonate lactone PST, methylene disulfonate MMDS, 1,3-dithiane, propylene sulfite, dimethyl sulfoxide DMSO, and sulfolane.

[0011] Optionally, the positive electrode includes a positive electrode current collector and a positive electrode active material layer coated on at least one surface thereon; the negative electrode includes a negative electrode current collector and a negative electrode active material layer coated on at least one surface thereon; the positive electrode active material layer includes a positive electrode active material coating layer and a positive electrode active material uncoated area; the negative electrode active material layer includes a negative electrode active material coating area and a negative electrode active material uncoated area; wherein the uncoated area of ​​the positive electrode active material accounts for 1%-13% of the surface area of ​​the positive electrode current collector, and the uncoated area of ​​the negative electrode active material accounts for 1%-10% of the surface area of ​​the negative electrode current collector.

[0012] Optionally, the positive electrode active material coating layer includes a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent, wherein, calculated by mass percentage, the positive electrode active material accounts for 94%-97%, the positive electrode binder accounts for 1.5%-3%, and the positive electrode conductive agent accounts for 1.5%-3%. The positive electrode active material comprises a composite metal oxide of one or more transition metals, namely nickel, cobalt, manganese and aluminum, and lithium, wherein the content of nickel atoms accounts for more than 85% of the total content of all transition metal atoms; the positive electrode binder comprises any one or a combination of at least two of polyvinylidene fluoride, polyethylene glycol, polymethyl methacrylate or polyvinyl acetate; and the positive electrode conductive agent comprises one or more of carbon nanotubes, acetylene black, graphene and high-performance conductive carbon black Super-P.

[0013] Optionally, the negative electrode active material coating layer comprises a negative electrode active material, a negative electrode dispersant, a negative electrode binder, and a negative electrode conductive agent, wherein, calculated by mass percentage, the negative electrode active material accounts for 93%-97.5%, the negative electrode dispersant accounts for 0.4%-2.2%, the negative electrode binder accounts for 0.4%-2.1%, and the negative electrode conductive agent accounts for 0.4%-2.3%. The negative electrode active material includes one or a combination of at least two of the following: artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, soft carbon, and silicon-based materials. In the negative electrode active material, the mass of silicon accounts for 1%-20% of the total mass of the negative electrode active material. The negative electrode dispersant is carboxymethyl cellulose. The negative electrode binder includes styrene-butadiene rubber and / or polyacrylic acid. The negative electrode conductive agent includes one or a combination of at least two of the following: conductive carbon black, graphite, and carbon nanotubes.

[0014] Optionally, the battery core of the lithium-ion battery is a cylindrical battery core, wherein the diameter of the cylindrical battery core is 10mm-50mm and the height of the cylindrical battery core is 30mm-150mm.

[0015] Optionally, the areal density of the positive electrode is 9 mg / cm³. 2 -19mg / cm 2 The compacted density is 3.15 g / cm³. 3 -3.75g / cm 3 The areal capacity of the positive electrode is 2.15 g / cm³. 3 -2.58mAh / cm 2 The specific surface area of ​​the positive electrode is 1.5 m². 2 / g-22m 2 / g; the porosity of the positive electrode is 15%-52%; the areal density of the negative electrode is 6.3mg / cm³. 2 -9.2mg / cm 2The compacted density is 1.3 g / cm³. 3 -1.9g / cm 3 The areal capacity of the negative electrode is 1.4 mAh / cm². 2 -4.7mAh / cm 2 The specific surface area of ​​the negative electrode is 0.15m². 2 / g-12m 2 / g; the porosity of the negative electrode is 26%-62%.

[0016] Optionally, the rated capacity of the lithium-ion cylindrical battery is 4000mAh-24000mAh.

[0017] In some embodiments, the electrical device includes a lithium-ion battery as described in this application.

[0018] The lithium-ion battery and power-consuming device provided in this disclosure can achieve the following technical effects: First, suppress high-temperature gas generation and improve safety: This is achieved by controlling the mass percentage (W) of aluminum in the high-nickel material of the positive electrode active material. A The mass percentage of sulfur-containing compound H in the electrolyte, W K The range and proportion of these parameters ensure that, after the lithium-ion battery of this application is stored in a high-temperature environment of 45℃-85℃ for the first target number of days, the total amount of gas generated is limited to a low range of 0.4mL-3.5mL, thereby reducing the risk of battery expansion, leakage, or thermal runaway. At capacity Q1, the lithium-ion battery of this application, stored at ambient temperature T2 for the second target number of days, exhibits an AC internal resistance growth rate ranging from 15% to 30%. The matching of the electrolyte additives and high-nickel materials effectively reduces the battery's internal resistance, thereby reducing its own heat generation during operation and increasing its output power.

[0019] Secondly, improved interface stability and extended cycle life: Sulfur-containing compounds (such as sulfates) in the electrolyte can form a stable interface film on the surface of the positive electrode, suppressing side reactions between the high-nickel material and the electrolyte; simultaneously, aluminum doping enhances the structural stability of the positive electrode material. These two factors synergistically reduce active lithium loss, resulting in slower capacity decay at high temperatures and improved cycle life.

[0020] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0021] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein: Figure 1 This is a schematic diagram of the structure of a lithium-ion battery provided in an embodiment of this disclosure; Figure 2 This is a schematic diagram of the structure of a lithium-ion battery provided in an embodiment of this disclosure; Figure 3 This is a schematic diagram of a lithium-ion battery provided in an embodiment of this disclosure.

[0022] Figure label: 1-Positive terminal; 10-Battery core; 11-Positive terminal post; 12-Negative terminal; 2-Shell; 3-Negative electrode sheet; 4-Separator; 5-Positive electrode sheet. Detailed Implementation

[0023] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0024] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0025] In this disclosure, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for better description of the embodiments of this disclosure and their implementations, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the embodiments of this disclosure according to the specific circumstances.

[0026] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0027] Unless otherwise stated, the term "multiple" means two or more.

[0028] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0029] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in the present disclosure can be combined with each other.

[0031] Combination Figure 1 As shown, this embodiment of the present disclosure provides a lithium-ion battery, including a cylindrical casing 2, the interior of which is used to house a battery core, the top being a positive terminal 1, and the bottom being a negative terminal 12. A positive electrode post 11 is disposed on the positive terminal 1. Specifically, Figure 2 A schematic diagram of the battery core structure in this application is shown. Figure 3 A schematic diagram of the unfolded battery core of this application is shown. The lithium-ion battery includes a positive electrode 5, a negative electrode 3, a separator 4, and an electrolyte, wherein the positive electrode 5, the negative electrode 3, and the separator 4 are as follows: Figure 3 As shown, layers are stacked and then wound to form a shape like... Figure 2 The cylindrical battery core 10 shown is initially wound at the electrode end along the cylinder axis, and ends at the electrode end on the outer surface of the cylinder after winding.

[0032] The positive electrode 5 of this application includes a positive current collector and a positive active material layer coated on at least one surface thereon; the negative electrode 3 includes a negative current collector and a negative active material layer coated on at least one surface thereon; the positive active material layer includes a positive active material coating layer and a positive active material uncoated area; the negative active material layer includes a negative active material coating area and a negative active material uncoated area; wherein the uncoated area of ​​the positive active material accounts for 1%-13% of the surface area of ​​the positive current collector, and the uncoated area of ​​the negative active material accounts for 1%-10% of the surface area of ​​the negative current collector.

[0033] Furthermore, the positive electrode active material coating layer of this application comprises a positive electrode active material, a positive electrode binder, and a positive electrode conductive agent, wherein, preferably, by mass percentage, the positive electrode active material accounts for 94%-97%, the positive electrode binder accounts for 1.5%-3%, and the positive electrode conductive agent accounts for 1.5%-3%. And, the negative electrode active material coating layer of this application comprises a negative electrode active material, a negative electrode dispersant, a negative electrode binder, and a negative electrode conductive agent, wherein, preferably, by mass percentage, the negative electrode active material accounts for 93%-97.5%, the negative electrode dispersant accounts for 0.4%-2.2%, the negative electrode binder accounts for 0.4%-2.1%, and the negative electrode conductive agent accounts for 0.4%-2.3%.

[0034] In this way, by limiting the ratio of positive electrode to negative electrode to a reasonable range, not only can the energy density of the battery be improved, but the high content of active materials directly increases the energy density per unit volume of the battery. This is a core requirement for lithium-ion batteries in products such as power tools, drones, and robots.

[0035] Electrochemical performance can also be optimized: optimized electrode electron transport and interfacial stability significantly improve battery charge / discharge efficiency and cycle life. This, in turn, ensures structural stability: appropriate amounts of binder can "significantly enhance the adhesion between the active material and the current collector in the electrode," preventing the active material from detaching from the electrode. Simultaneously, battery consistency is improved: appropriate amounts of dispersant and conductive agent can significantly reduce the increase in dynamic internal resistance and voltage differential consistency of the battery pack, extending the lifespan of lithium-ion batteries.

[0036] It should be noted that the positive electrode active material in this application is a high-nickel material, and the mass percentage of aluminum in the high-nickel material is W. A W A The numerical range is 0.01wt%-0.2wt%; the electrolyte includes sulfur-containing compound H, and the mass percentage of sulfur-containing compound H in the electrolyte is W. K W K The numerical range is 0.1wt%-2wt%; and W A and W K The proportional relationship is satisfied: 0.5 ≤ W K / W A ≤200.

[0037] Furthermore, the lithium-ion battery of this application, at capacity Q1 and stored at ambient temperature T1 for a first target number of days, produces a total gas volume of V1, with a value ranging from 0.4 mL to 3.5 mL. At capacity Q1 and stored at ambient temperature T2 for a second target number of days, the AC internal resistance increases by a rate ranging from 15% to 30%. Ambient temperature T1 satisfies 45℃ ≤ T1 ≤ 85℃, and ambient temperature T2 satisfies 45℃ ≤ T2 ≤ 60℃. Q1 is the capacity of a fully charged lithium-ion battery (4.2V) obtained by placing it at 25℃ for 1 hour in a depleted state and then charging it at a constant current and constant voltage of 0.5C. The first target number of days is less than the second target number of days. Optionally, the first target number of days is 2 to 4 days (preferably 3 days), and the second target number of days is 95 to 105 days (preferably 100 days). For example, if stored at an ambient temperature T1 for 3 days, the total amount of gas produced, V1, is in the range of 0.4 mL ≤ V1 ≤ 3.5 mL.

[0038] Thus, by using the lithium-ion battery provided in this embodiment, the following technical effects can be achieved: First, suppress high-temperature gas generation and improve safety: This is achieved by controlling the mass percentage (W) of aluminum in the high-nickel material of the positive electrode active material. A The mass percentage of sulfur-containing compound H in the electrolyte, W K The range and proportion of these parameters ensure that, after the lithium-ion battery of this application is stored in a high-temperature environment of 45℃-85℃ for the first target number of days, the total amount of gas generated is limited to a low range of 0.4mL-3.5mL, thereby reducing the risk of battery expansion, leakage, or thermal runaway. At capacity Q1, after storage at ambient temperature T2 for the second target number of days, the AC internal resistance of the lithium-ion battery increases by a range of 15%-30%. The matching of the electrolyte additives and high-nickel materials can effectively reduce the battery's internal resistance, thereby reducing the heat generated by the battery during operation and increasing the output power.

[0039] Secondly, improved interface stability and extended cycle life: Sulfur-containing compounds (such as sulfates) in the electrolyte can form a stable interface film on the surface of the positive electrode, suppressing side reactions between the high-nickel material and the electrolyte; simultaneously, aluminum doping enhances the structural stability of the positive electrode material. These two factors synergistically reduce active lithium loss, resulting in slower capacity decay at high temperatures and improved cycle life.

[0040] In one embodiment of this application, the positive electrode active material comprises a composite metal oxide of one or more transition metals nickel, cobalt, manganese, and aluminum with lithium (preferably lithium nickel cobalt manganese aluminum oxide, with the chemical formula Li[Ni a Co b Mn c Al dO2; wherein, 0.85≤a≤0.93, 0.01≤b≤0.1, 0.1≤c≤0.1, 0.01≤d≤0.03), and the content of nickel atoms accounts for more than 85% of the total content of all transition metal atoms. The positive electrode binder includes any one or a combination of at least two of polyvinylidene fluoride, polyethylene glycol, polymethyl methacrylate, or polyvinyl acetate. The positive electrode conductive agent includes one or more of carbon nanotubes, acetylene black, graphene, and high-performance conductive carbon black Super-P.

[0041] Optionally, at least one edge of the positive electrode active material coating region has an inorganic ceramic coating region, the inorganic ceramic coating comprising inorganic material particles. The inorganic material particles may be selected from one or a combination of at least two of the following: aluminum oxide, manganese dioxide, magnesium oxide, silicon dioxide, titanium dioxide, zirconium dioxide, zinc oxide, ferric oxide, boehmite, gypsum, talc, or calcite.

[0042] In this way, by having an inorganic ceramic coating area at at least one edge of the positive electrode active material coating area, it can firstly serve as an insulating layer to prevent short circuits between the positive and negative electrodes, thus preventing battery thermal runaway; secondly, it can serve as a puncture-proof layer, because metal debris and burrs will appear after the electrode is cut. After the electrode edge is set with a ceramic coating, it can prevent metal debris and burrs from puncturing the separator, thereby improving the battery safety boundary.

[0043] In another embodiment of this application, the negative electrode active material comprises one or a combination of at least two of the following: artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, soft carbon, and silicon-based materials. Furthermore, the mass of silicon in the negative electrode active material accounts for 1%-20% of the total mass of the negative electrode active material. The negative electrode dispersant is carboxymethyl cellulose. The negative electrode binder comprises styrene-butadiene rubber and / or polyacrylic acid. The negative electrode conductive agent comprises one or a combination of at least two of the following: conductive carbon black, graphite, and carbon nanotubes.

[0044] Thus, with the increasing demands of applications such as power tools, improving battery energy density within limited space has become an increasingly urgent need. Adding a certain amount of silicon-based materials, such as silicon-carbon or silicon-oxygen materials, to graphite, the traditional negative electrode active material, can significantly improve the battery's discharge capacity and energy density.

[0045] In another embodiment of this application, the electrolyte comprises a sulfur-containing compound H, lithium hexafluorophosphate, lithium salt additives, and a solvent; wherein, by mass percentage, the lithium hexafluorophosphate accounts for 12%-20%, the sulfur-containing compound H accounts for 0.1%-2%, and the remainder is lithium salt additives and solvents.

[0046] Optionally, the sulfur-containing compound H in this application includes one or more of vinyl sulfate DTD, propylene sulfate TS, vinyl sulfite ES, 1,3-propanediol cyclosulfonate PCS, 1,3-propanesulfonate lactone PS, 1,3-propenesulfonate lactone PST, methylene disulfonate MMDS, 1,3-dithiane, propylene sulfite, dimethyl sulfoxide DMSO, and sulfolane. Thus, the sulfur-containing compound H primarily functions as a film-forming additive, capable of protecting the electrode interface.

[0047] Optionally, the lithium salt additives of this application include one or more of lithium difluorophosphate (LiPO2F2), lithium bis(fluorosulfonyl)imide (LIFSI), lithium bis(trifluoromethanesulfonyl)imide (LITFSI), lithium difluorooxalateborate (LiDFOB), lithium difluorooxalate phosphate (LiDFOP), and lithium dioxalateborate (LiBOB). Thus, the lithium salt additives can improve conductivity, stability, and wide-temperature performance.

[0048] Optionally, the solvent in this application includes any one or a combination of at least two of ethylene carbonate, ethyl acetate, diethyl carbonate, dimethyl carbonate, or methyl ethyl carbonate. Thus, the electrolyte of this application, through the synergistic effect of sulfur compound H, lithium hexafluorophosphate, lithium salt additives, and solvent, can significantly improve the cycle life, safety, high and low temperature performance, and rate performance of lithium-ion batteries.

[0049] Optionally, the battery core of the lithium-ion battery in this application is a cylindrical battery core, wherein the diameter of the cylindrical battery core is 10mm-50mm and the height of the cylindrical battery core is 30mm-150mm.

[0050] Optionally, the areal density of the positive electrode in this application is 9 mg / cm³. 2 -19mg / cm 2 The compacted density is 3.15 g / cm³. 3 -3.75g / cm 3 The areal capacity of the positive electrode is 2.15 g / cm³. 3 -2.58mAh / cm 2 The specific surface area of ​​the positive electrode is 1.5 m². 2 / g-22m 2 / g; the porosity of the positive electrode is 15%-52%; the areal density of the negative electrode is 6.3mg / cm³. 2 -9.2mg / cm 2 The compacted density is 1.3 g / cm³. 3 -1.9g / cm 3 The areal capacity of the negative electrode is 1.4 mAh / cm². 2 -4.7mAh / cm 2 The specific surface area of ​​the negative electrode is 0.15m². 2 / g-12m 2 / g; the porosity of the negative electrode is 26%-62%.

[0051] In this way, the areal density and compaction density of the positive and negative electrodes in the lithium-ion battery of this application are optimized and matched to maximize the volumetric energy density while ensuring the integrity of the electrode sheets. Simultaneously, the positive and negative electrodes employ appropriate porosity ranges to buffer the volume expansion of the electrode materials, reducing the shedding of active material. Furthermore, a moderate compaction density can prevent particle breakage and interface deterioration caused by overpressure.

[0052] Furthermore, a well-designed porosity profile for both positive and negative electrodes ensures a rapid lithium-ion transport pathway. Appropriate specific surface areas on both electrodes provide ample electrochemical reaction sites. A capacity margin design on the negative electrode surface prevents lithium deposition and dendrite growth; matching the capacities of the positive and negative electrodes avoids the risks of overcharging and over-discharging.

[0053] Optionally, the rated capacity of the lithium-ion cylindrical battery of this application is 4000mAh-24000mAh.

[0054] Optionally, the AC internal resistance (ACR) of the lithium-ion cylindrical battery of this application is less than 10 mΩ.

[0055] Furthermore, embodiments of this disclosure also provide an electrical device including a lithium-ion battery as described in this application.

[0056] The present invention will be further explained and illustrated below with reference to embodiments.

[0057] Example 1 This embodiment 1 provides a method for preparing a lithium-ion battery as follows: (1) Preparation of positive electrode sheet Composition of the positive electrode: The positive electrode comprises a positive current collector aluminum foil and a positive electrode coating applied to both sides of the aluminum foil; wherein, by mass percentage, the positive electrode coating comprises 96.0% LiNi. 0.87 Co 0.05 Mn 0.06 Al 0.02 O2 (NCMA); 0.5% carbon nanotube conductive agent; 2.0% Super-P (conductive carbon black) conductive agent and 1.5% polyvinylidene fluoride (PVDF) binder; The preparation steps of the positive electrode sheet are as follows: the raw materials in the above positive electrode coating are added to N-methylpyrrolidone and stirred to form a positive electrode slurry with a solid content of 60 wt%. The positive electrode slurry is then coated on the positive electrode current collector aluminum foil to form a positive electrode sheet. (2) Preparation of negative electrode sheet Composition of the negative electrode sheet: The negative electrode sheet includes a negative current collector copper foil and a negative electrode coating coated on both sides of the copper foil; wherein, calculated by mass percentage, the negative electrode coating includes 81.5% artificial graphite; 14% silicon; 1.5% conductive agent acetylene black; and 3% polyacrylic acid binder. The preparation steps of the negative electrode sheet are as follows: the above substances are added to deionized water and stirred to form a negative electrode slurry with a solid content of 42%, which is then coated on the negative electrode current collector to form a negative electrode sheet. (3) Prepare the electrolyte by mixing ethylene carbonate EC, dimethyl carbonate DMC and ethyl methyl carbonate EMC in a mass percentage of 15%:50%:15% to obtain an organic solvent. Then, fully dried 15% lithium salt LiPF6 is dissolved in the mixed organic solvent to prepare an electrolyte with a concentration of 1.1 mol / L. Add electrolyte additives of 1 wt% methanedisulfonate MMDS, 2% fluoroethylene carbonate FEC and 2% vinylene carbonate. (4) Preparation of diaphragm The membrane consists of a high-porosity dynamic membrane, a PE base membrane with a thickness of 10 μm, ceramic coatings on both sides with a thickness of 1 μm, and a PVDF coating with a thickness of 1 μm. The membrane has an air permeability of 100 s / 100 mL. (5) Assembly of lithium-ion cylindrical batteries: After the positive and negative electrode sheets are rolled, slit, and die-cut, they are wound together with the separator. The positive, negative, and separator are wound together by a winding machine to form a core. The core is then cut and stacked with positive and negative electrode tabs. The positive and negative busbars are then welded to the core, and the negative busbars are welded to the steel shell. An insulating sheet is placed on top of the positive busbar, and the positive busbar is welded to the cap to obtain the lithium-ion battery core. This core is then installed in a cylindrical battery casing. After liquid injection, sealing, and formation processes, a 21700 cylindrical lithium-ion battery is obtained, with a diameter of 21 mm, a height of 70 mm, and a capacity of 6.0 Ah. The table below shows the gas production of the lithium-ion cylindrical battery provided in this comparative example at three ambient temperatures (45℃, 60℃, and 85℃) and the ACR growth rate at two ambient temperatures (45℃ and 60℃).

[0058] Example 2 This embodiment provides a lithium-ion cylindrical battery, which differs from Embodiment 1 in that the content of the sulfur-containing compound methane disulfonate methylene ester (MMDS) is reduced to 0.8 wt%.

[0059] The table below shows the gas production of the lithium-ion cylindrical battery provided in this comparative example at three ambient temperatures (45℃, 60℃, and 85℃) and the ACR growth rate at two ambient temperatures (45℃ and 60℃).

[0060] Example 3 This embodiment provides a lithium-ion cylindrical battery, which differs from Embodiment 1 in that the content of the sulfur-containing compound methane disulfonate methylene ester (MMDS) is reduced to 0.5 wt%.

[0061] The table below shows the gas production of the lithium-ion cylindrical battery provided in this comparative example at three ambient temperatures (45℃, 60℃, and 85℃) and the ACR growth rate at two ambient temperatures (45℃ and 60℃).

[0062] Example 4 This embodiment provides a lithium-ion cylindrical battery, which differs from Embodiment 1 in that the aluminum content W in the positive electrode material NCMA is different. A The content of sulfur-containing compound methane disulfonate methylene ester (MMDS) was increased to 0.05 wt%, while the content of MMDS was reduced to 0.5 wt%.

[0063] The table below shows the gas production of the lithium-ion cylindrical battery provided in this comparative example at three ambient temperatures (45℃, 60℃, and 85℃) and the ACR growth rate at two ambient temperatures (45℃ and 60℃).

[0064] Example 5 This embodiment provides a lithium-ion cylindrical battery, which differs from Embodiment 1 in that the aluminum content W in the positive electrode material NCMA is different. A The content of sulfur-containing compound methane disulfonate methylene ester (MMDS) was increased to 0.2 wt%, while the content of MMDS was reduced to 0.2 wt%.

[0065] The table below shows the gas production of the lithium-ion cylindrical battery provided in this comparative example at three ambient temperatures (45℃, 60℃, and 85℃) and the ACR growth rate at two ambient temperatures (45℃ and 60℃).

[0066] Example 6 This embodiment provides a lithium-ion cylindrical battery, which differs from Embodiment 1 in that the content of lithium hexafluorophosphate is increased to 18%.

[0067] The table below shows the gas production of the lithium-ion cylindrical battery provided in this comparative example at three ambient temperatures (45℃, 60℃, and 85℃) and the ACR growth rate at two ambient temperatures (45℃ and 60℃).

[0068] The lithium-ion cylindrical batteries provided in the above embodiments have a gas production V1 of 0.4 mL ≤ V1 ≤ 3.3 mL at three ambient temperatures of 45°C, 60°C and 85°C; and an ACR growth rate of 17%-28%.

[0069] Comparative Example 1 This comparative example provides a lithium-ion cylindrical battery, which differs from Example 1 in that the electrolyte does not contain sulfur-containing compound H.

[0070] The table below shows the gas production of the lithium-ion cylindrical battery provided in this comparative example at three ambient temperatures (45℃, 60℃, and 85℃) and the ACR growth rate at two ambient temperatures (45℃ and 60℃).

[0071] Comparative Example 2 This comparative example provides a lithium-ion cylindrical battery, which differs from Example 1 in that the aluminum content W in the positive electrode material NCMA is different. A The content of sulfur-containing compound methane disulfonate methylene ester (MMDS) was increased to 0.5 wt%, while the content of MMDS was reduced to 0 wt%.

[0072] The table below shows the gas production of the lithium-ion cylindrical battery provided in this comparative example at three ambient temperatures (45℃, 60℃, and 85℃) and the ACR growth rate at two ambient temperatures (45℃ and 60℃).

[0073] Comparative Example 3 This comparative example provides a lithium-ion cylindrical battery, which differs from Example 1 in that the aluminum content W in the positive electrode material NCMA is different. A Increased to 0.5 wt%.

[0074] The table below shows the gas production of the lithium-ion cylindrical battery provided in this comparative example at three ambient temperatures (45℃, 60℃, and 85℃) and the ACR growth rate at two ambient temperatures (45℃ and 60℃).

[0075] As can be seen from the comparison between Examples 1 and Examples 2-3, when the content of the sulfur-containing compound methane disulfonate methylene ester (MMDS) in the electrolyte is reduced, the gas production of the lithium-ion battery increases after 3 days of storage at different temperatures, and the AC resistance (ACR) increases after 100 days of storage, thereby deteriorating the electrochemical performance of the battery.

[0076] A comparison of Examples 1 and 4-5 shows that when the aluminum content in the positive electrode material is increased, the AC resistance (ACR) of the lithium-ion battery decreases after 100 days of storage, thus improving the battery's electrical performance. However, when the content of the sulfur-containing compound methane disulfonate methylene ester (MMDS) in the electrolyte is reduced, the gas production of the lithium-ion battery increases or remains unchanged after 3 days of storage at different temperatures, thus reducing the battery's storage performance and shortening its lifespan.

[0077] A comparison of Examples 1 and 6 shows that when the lithium salt content in the lithium-ion electrolyte is increased, the gas production of the battery increases, while the AC resistance (ACR) of the lithium-ion battery after 100 days of storage decreases slightly.

[0078] As can be seen from the comparison between Example 1 and Comparative Example 1, when no sulfur-containing compound H is added to the electrolyte, the gas production of the lithium-ion battery and the AC resistance ACR after 100 days of battery storage will increase significantly, which will deteriorate the battery performance and shorten the battery life.

[0079] As can be seen from the comparison between Example 1 and Comparative Example 2, increasing the aluminum content of the cathode material and not adding electrolyte additive H will increase the battery gas production and battery storage ACR. This shows that the lack of electrolyte additive H has a greater impact on battery performance than simply increasing the aluminum content of the cathode material.

[0080] As can be seen from the comparison between Example 1 and Comparative Example 3, when the aluminum content in the positive electrode material is too high, the gas production will increase significantly after 3 days of storage, and the ACR will also increase significantly after 100 days of storage, which will significantly deteriorate the performance of the battery.

[0081] The specific test methods and steps for each performance aspect are as follows: Gas production test method: The gas production of cylindrical lithium-ion batteries was detected using Yuaneng Technology's GVM2100 in-situ cell gas production volume monitoring instrument.

[0082] ACR testing method: Using a universal tester, let R1 be the AC internal resistance (ACR) measured before the storage experiment begins, and R2 be the AC internal resistance (ACR) measured after the storage experiment ends. Then, the ACR growth rate is 100%. (R2-R1) / R1.

[0083] 25℃ Rate Discharge Performance Test Method: The lithium-ion cylindrical battery was placed in a 25°C constant temperature chamber for 4 hours and tested according to the following steps: (1) Charge the battery to 4.2 V under constant current and constant voltage conditions at 0.1C, cut off the current at 0.01C, and let it stand for 30 minutes; (2) Discharge under constant current at 0.1C until cutoff at 2.5V, with capacity meter Q2 and energy meter W2, and let stand for 30 minutes; (3) Charge the battery to 4.2V under constant current and constant voltage conditions at 0.1C, with a cutoff current of 0.01C, and let it stand for 30 minutes; (4) Discharge under constant current at 6C until 2.5V cutoff, with capacity meter Q3 and energy meter W3, and let stand for 30 minutes; The 6C capacity retention rate is calculated as: Q3 / Q2 × 100%; The 6C energy retention rate is calculated as: W3 / W2×100%.

[0084] The 6C discharge capacity retention and 6C discharge energy retention of Examples 1 to 6 and Comparative Examples 1 to 3 are shown in the table below:

[0085] As can be seen from the test results of the above embodiments and comparative examples, only when the material components and electrolyte components in the cathode material are both within a suitable numerical range and have a reasonable matching relationship can they work together to improve the 6C discharge capacity retention rate and 6C discharge energy retention rate of the lithium-ion battery, thereby improving the battery efficiency.

[0086] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. Embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A lithium-ion battery, comprising a positive electrode, a negative electrode, and an electrolyte, characterized in that, The positive electrode active material in the positive electrode sheet is a high-nickel material, and the mass percentage of aluminum in the high-nickel material is W. A W A The numerical range is 0.01wt%-0.2wt%; the electrolyte includes a sulfur-containing compound H, and the mass percentage of sulfur-containing compound H in the electrolyte is W. K W K The numerical range is 0.1wt%-2wt%; and W A and W K The proportional relationship is satisfied: 0.5 ≤ W K / W A ≤200; as well as ， When the lithium-ion battery is stored at a capacity of Q1 and an ambient temperature of T1 for a first target number of days, the total amount of gas produced is V1, and the value of V1 ranges from 0.4 mL to 3.5 mL. The lithium-ion battery, at capacity Q1, experiences a second target number of days of storage at ambient temperature T2, with an AC internal resistance growth rate ranging from 15% to 30%. Wherein, the ambient temperature T1 satisfies 45℃≤T1≤85℃, the ambient temperature T2 satisfies 45℃≤T2≤60℃, Q1 is the full-charge capacity of a lithium-ion battery in an empty state after being left to stand at 25℃ for 1 hour and then charged to 4.2V at a constant current and constant voltage of 0.5C, and the first target number of days is less than the second target number of days.

2. The lithium-ion battery according to claim 1, characterized in that, The first target number of days is 2 to 4 days, and the second target number of days is 95 to 105 days.

3. The lithium-ion battery according to claim 1, characterized in that, The electrolyte also includes lithium hexafluorophosphate, lithium salt additives, and solvents; Of which, by mass percentage, lithium hexafluorophosphate accounts for 12%-20%, sulfur-containing compound H accounts for 0.1%-2%, and the remainder is lithium salt additives and solvents.

4. The lithium-ion battery according to claim 3, characterized in that, The sulfur-containing compound H includes one or more of the following: vinyl sulfate DTD, propylene sulfate TS, vinyl sulfite ES, 1,3-propanediol cyclosulfonate PCS, 1,3-propanesulfonate lactone PS, 1,3-propenesulfonate lactone PST, methylene disulfonate MMDS, 1,3-dithiane, propylene sulfite, dimethyl sulfoxide DMSO, and sulfolane.

5. The lithium-ion battery according to any one of claims 1 to 4, characterized in that, The positive electrode includes a positive electrode current collector and a positive electrode active material layer coated on at least one surface thereon; the negative electrode includes a negative electrode current collector and a negative electrode active material layer coated on at least one surface thereon; the positive electrode active material layer includes a positive electrode active material coating layer and an uncoated positive electrode active material area; the negative electrode active material layer includes a negative electrode active material coating area and an uncoated negative electrode active material area; wherein the uncoated positive electrode active material area accounts for 1%-13% of the surface area of ​​the positive electrode current collector, and the uncoated negative electrode active material area accounts for 1%-10% of the surface area of ​​the negative electrode current collector.

6. The lithium-ion battery according to claim 5, characterized in that, The positive electrode active material coating layer comprises positive electrode active material, positive electrode binder, and positive electrode conductive agent. By mass percentage, the positive electrode active material accounts for 94%-97%, the positive electrode binder accounts for 1.5%-3%, and the positive electrode conductive agent accounts for 1.5%-3%. The positive electrode active material includes a composite metal oxide of one or more transition metals, such as nickel, cobalt, manganese and aluminum, and lithium, wherein the content of nickel atoms accounts for more than 85% of the total content of all transition metal atoms. The positive electrode binder includes any one or a combination of at least two of polyvinylidene fluoride, polyethylene glycol, polymethyl methacrylate, or polyvinyl acetate. The positive electrode conductive agent includes one or more of carbon nanotubes, acetylene black, graphene, and conductive carbon black.

7. The lithium-ion battery according to claim 5, characterized in that, The negative electrode active material coating layer comprises a negative electrode active material, a negative electrode dispersant, a negative electrode binder, and a negative electrode conductive agent. By mass percentage, the negative electrode active material accounts for 93%-97.5%, the negative electrode dispersant accounts for 0.4%-2.2%, the negative electrode binder accounts for 0.4%-2.1%, and the negative electrode conductive agent accounts for 0.4%-2.3%. The negative electrode active material includes one or a combination of at least two of the following: artificial graphite, natural graphite, mesophase carbon microspheres, hard carbon, soft carbon, and silicon-based materials; and the mass of silicon element accounts for 1%-20% of the total mass of the negative electrode active material. The negative electrode dispersant is carboxymethyl cellulose; The negative electrode binder includes styrene-butadiene rubber and / or polyacrylic acid; The negative electrode conductive agent includes one or a combination of at least two of conductive carbon black, graphite, and carbon nanotubes.

8. The lithium-ion battery according to claim 1, characterized in that, The lithium-ion battery core is a cylindrical battery core, wherein the diameter of the cylindrical battery core is 10mm-50mm and the height of the cylindrical battery core is 30mm-150mm.

9. The lithium-ion battery according to claim 1, characterized in that, The areal density of the positive electrode is 9 mg / cm³. 2 -19mg / cm 2 The compacted density is 3.15 g / cm³. 3 -3.75g / cm 3 The areal capacity of the positive electrode is 2.15 g / cm³. 3 -2.58mAh / cm 2 The specific surface area of ​​the positive electrode is 1.5 m². 2 / g-22m 2 / g; the porosity of the positive electrode is 15%-52%; The areal density of the negative electrode is 6.3 mg / cm³. 2 -9.2mg / cm 2 The compacted density is 1.3 g / cm³. 3 -1.9g / cm 3 The areal capacity of the negative electrode is 1.4 mAh / cm². 2 -4.7mAh / cm 2 The specific surface area of ​​the negative electrode is 0.15m². 2 / g-12m 2 / g; the porosity of the negative electrode is 26%-62%.

10. The lithium-ion battery according to claim 1, characterized in that, The rated capacity of the lithium-ion cylindrical battery is 4000mAh-24000mAh.

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