Positive electrode material and preparation method thereof, cathode electrode piece, electrode assembly, battery, and electric device

Abstract

The application relates to the technical field of batteries, in particular to a positive electrode material and a preparation method thereof, a cathode sheet, an electrode assembly, a battery and an electric device. The positive electrode material comprises a layered lithium-containing metal oxide, and the layered lithium-containing metal oxide comprises other cations with a larger ionic radius than lithium ions. The other cations in the positive electrode material are larger than lithium ions, can play a supporting role in the layered structure, enhance the mixing energy barrier, prevent the mixing of metal ions and lithium ions in the layered cathode from being intensified, improve the stability of the layered structure and thus improve the cycle performance, and the other cations in the positive electrode material can also be embedded into a negative electrode material, wherein the other cations with a larger ionic radius play a supporting role in the graphite, so that the expansion / contraction of the graphite caused by the ions with a smaller ionic radius in the embedding / detaching process is reduced, the stability of the SEI film is improved, the consumption of active lithium is reduced, and the cycle performance is improved.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a positive electrode material and its preparation method, a cathode electrode, an electrode assembly, a battery, and an electrical device. Background Technology

[0002] With the rapid growth of portable electronic devices, electric vehicles, and other technologies, the demand for power batteries is also constantly increasing. Among these, the electrochemical performance of batteries is receiving increasing attention.

[0003] In layered cathode materials, the presence of mixed lithium and metal elements results in a poor overall lifespan. For example, an increase in nickel content leads to more lithium-nickel mixing, reducing battery cycle life. Summary of the Invention

[0004] The main objective of this invention is to provide a positive electrode material that aims to improve the cycle life of batteries.

[0005] To achieve the above objectives, the present invention proposes a cathode material comprising a layered lithium-containing metal oxide, wherein the layered lithium-containing metal oxide includes other cations with radii larger than lithium ions.

[0006] The radii of other cations in the cathode material are larger than those of lithium ions, which can provide support for the layered material, enhance the mixing barrier, prevent the intensification of mixing between metal ions and lithium ions in the layered cathode, improve the stability of the layered structure, and thus improve cycle performance. At the same time, other cations in the cathode material can also be inserted into the anode material. Among them, other cations with larger ionic radii provide support in graphite, thereby reducing the expansion / contraction of graphite caused by smaller ionic ions during insertion / extraction. This is beneficial to improving the stability of the SEI film, reducing the consumption of active lithium, and improving cycle performance.

[0007] Optionally, the layered lithium-containing metal oxide comprises a layered lithium-containing transition metal oxide; and / or

[0008] The ionic radius of the other cations is greater than 76 μm, and can be selected as greater than 84 μm and less than 100 μm.

[0009] Layered lithium-containing metal oxides include layered lithium-containing transition metal oxides. Compared with other metals, the transition metals in layered lithium-containing transition metal oxides are more likely to mix with lithium. Including other cations with radii larger than lithium ions in layered lithium-containing transition metal oxides can effectively improve the stability of the layered structure.

[0010] The lithium ion radius is 76Pm. Cations larger than 76Pm can effectively form a supporting effect in layered materials, improve the stability of the layered structure, and thus improve cycle performance.

[0011] Optionally, the ionic radii of other cations are greater than 84 Pm and less than 100 Pm, and the ionic radii of other cations are in the range of 84 Pm-100 Pm, so as to ensure that other cations are effectively embedded in the layered structure, which can play a supporting role in the layered material, enhance the mixing barrier, prevent the intensification of mixing between metal ions and lithium ions in the layered cathode, improve the stability of the layered structure, and thus improve the cycle performance.

[0012] Optionally, in the layered lithium-containing metal oxide structure, the position of the lithium ion is defined as a lithium site, and the other cations occupy at least a portion of the lithium sites in the layered lithium-containing metal oxide structure.

[0013] In layered lithium-containing metal oxide structures, each element has its own designated position. The position of a lithium ion in a layered lithium-containing metal oxide structure is defined as a lithium site, and other cations occupy at least a portion of these lithium sites. To reduce the mixing of lithium ions with metal ions, some lithium sites in the layered cathode material are replaced with other cations that have larger ionic radii. These other cations have larger radii and are more stable at the lithium sites, making further mixing less likely. This improves the stability of the layered structure, and the substitution of lithium sites with other cations effectively reduces the problem of lithium-nickel mixing.

[0014] Optionally, the other cationic elements include at least one of alkali metal elements, alkaline earth metal elements, and nonmetal elements other than lithium.

[0015] This application does not limit the types of other cations. Other cation elements include at least one of alkali metals, alkaline earth metals, and nonmetals, excluding lithium. It is understood that, theoretically, any cation with a radius larger than that of lithium ions is acceptable, but metal ions are preferred.

[0016] Optionally, the alkali metal element includes at least one selected from Na, K, Rb, and Cs;

[0017] The alkaline earth metal element includes at least one of Ca and Sr;

[0018] The non-metallic element includes Se.

[0019] It is understood that alkali metal elements include at least one of Na, K, Rb, and Cs; alkaline earth metal elements include at least one of Ca and Sr; and non-metallic elements include Se.

[0020] Optionally, the layered lithium-containing metal oxide has the general formula Li. x Y (2-x) Ni a Co b Mn cM (1-a-b-c) O₂, where Y represents the other cations, and M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, La; wherein, 0.3 ≤ a < 1.0, 0 < b < 0.5, 0 ≤ c ≤ 0.2, a + b + c ≤ 1, 0 < x < 2.

[0021] The demand and design of layered cathode materials have evolved from the earliest low-nickel materials to today's high-nickel materials. The overall lifespan of high-nickel materials is relatively poor. On the one hand, the increase in nickel content will inevitably lead to more lithium-nickel mixing, reducing the battery cycle life. Lithium-nickel mixing refers to the phenomenon that divalent nickel ions have a similar volume to lithium ions. When a large amount of lithium ions are extracted during discharge, under the influence of external factors, they occupy the positions in the lithium ion lattice. The dislocation of ions brings about a change in the lattice type, and its lithium insertion ability also changes accordingly. During the charge-discharge process, the pressure and speed of lithium deintercalation and intercalation on the surface of the cathode material are the greatest. Therefore, the surface often undergoes lattice changes due to this cation mixing, which is also called surface reconstruction. The higher the nickel content, the higher the probability of trivalent unstable nickel ions being reduced to divalent nickel ions, and the more opportunities for cation mixing, resulting in a more serious reduction in the battery cycle life.

[0022] In this application, a nickel-containing cathode material is used to improve the energy density. At the same time, based on the presence of other cations with a larger radius than lithium ions in the cathode material, it can effectively prevent the exacerbation of nickel ion and lithium ion mixing in the layered cathode, enhance the stability of the layered structure, and thus improve the cycle performance.

[0023] General formula Li x Y (2-x) Ni a Co b Mn c M (1-a-b-c) O₂, 0 < x < 2. In the case of x > 1, it indicates that the cathode material can be a lithium-rich material, such as lithium-rich manganese-based materials.

[0024] Optionally, 0.6 ≤ a < 1.0, 0.3 < b < 0.5.

[0025] In the general formula Li x Y (2-x) Ni a Co b Mn c M (1-a-b-c) O₂, 0.6 ≤ a < 1.0, 0.3 < b < 0.5, indicating that the cathode material is a high-nickel material. In the case of effectively preventing the exacerbation of nickel ion and lithium ion mixing in the layered cathode, enhancing the stability of the layered structure, and thus improving the cycle performance, using a high-nickel material can effectively improve the energy density.

[0026] Optionally, 0 < x < 1.

[0027] When 0 < x < 1, the positive electrode material can be a ternary material. Among the transition metals in the ternary material, it is easier to have lithium mixing with other metals. At this time, 0 < x < 1 indicates that in the general formula, Li x Y (2-x) Ni a Co b Mn c M (1-a-b-c) in O2, the content of other cations represented by Y increases. The increase in the content of other cations is beneficial to increasing the mixing barrier energy, preventing the intensification of the mixing of transition metal ions and lithium ions in the layered cathode, enhancing the stability of the layered structure and thus improving the cycling performance.

[0028] This application also provides a preparation method of a positive electrode material, including the following steps:

[0029] Adding a metal salt into a solvent and stirring to obtain a metal salt solution;

[0030] Adding a precipitating agent to the metal salt solution to obtain a precursor;

[0031] Mixing the precursor, a lithium salt and a salt of other cations, and calcining to obtain a layered lithium-containing metal oxide;

[0032] Wherein, the radius of the other cations in the salt of the other cations is greater than the radius of lithium ions.

[0033] Adding a metal salt into a solvent and stirring to obtain a metal salt solution; adding a precipitating agent to the metal salt solution to obtain a precursor; mixing the precursor, a lithium salt and a salt of other cations, and calcining to obtain a layered lithium-containing metal oxide; wherein, the radius of the other cations in the salt of the other cations is greater than the radius of lithium ions.

[0034] Precipitating the metal salt with a precipitating agent to obtain a precursor, and mixing the precursor with a lithium salt and a salt of other cations, and calcining to obtain a layered lithium-containing metal oxide, wherein, the radius of the other cations in the salt of the other cations is greater than the radius of lithium ions.

[0035] The other cations in the positive electrode material are larger than the radius of lithium ions, which can play a supporting role in the layered material, enhance the mixing barrier energy, prevent the intensification of the mixing of metal ions and lithium ions in the layered cathode, enhance the stability of the layered structure and thus improve the cycling performance. At the same time, the other cations in the positive electrode material can also be embedded into the negative electrode material. Among them, the other cations with larger ionic radii play a supporting role in graphite, thereby reducing the expansion / contraction of graphite caused by the ions with smaller ionic radii during the insertion / extraction process, being beneficial to improving the stability of the SEI film, reducing the consumption of active lithium, and improving the cycling performance.

[0036] Optionally, the other cation salts include at least one of alkali metal salts, alkaline earth metal salts, and non-metal salts.

[0037] This application does not limit the types of salts of other cations, which include at least one of alkali metal salts, alkaline earth metal salts, and non-metal salts. It is understood that, theoretically, any element with a radius larger than that of the lithium ion is acceptable, with metal ions being preferred.

[0038] Optionally, the step of adding a precipitant to the metal salt solution to obtain the precursor includes the following steps;

[0039] A precipitant is added to the metal salt solution, and the reaction is carried out for 3-20 hours, followed by aging for 2-12 hours to obtain the precursor.

[0040] Understandably, the reaction time is 3-20 hours. ， This reaction time is used to generate primary particles. Since particle breakage occurs during the reaction process, aging for 2-12 hours can help repair and grow the lattice of primary particles.

[0041] The values ​​in the range 3h-20h include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 3h, 5h, 8h, 10h, 14h, 16h, 18h, 20h, etc.

[0042] Optionally, in the step of mixing the precursor, lithium salt and other cation salts, calcining, and obtaining layered lithium metal oxide, the molar ratio of the precursor, lithium salt and other cation salts is defined as P:Q:R, then (Q+R) / P≥1.07 is satisfied.

[0043] The excess lithium salt and other cation salts are added to compensate for the loss of lithium and other cations during high-temperature calcination. Therefore, in the step of mixing the precursor, lithium salt and other cation salts, calcining, and obtaining layered lithium metal oxide, the lithium salt and other cation salts are added in excess.

[0044] Optionally, the calcination time in the calcination process is 17h-28h.

[0045] During calcination, lithium and other cationic elements can be incorporated into the precursor material's lattice more quickly and uniformly, thereby maximizing the doping effect of each dopant element. The values ​​within the range of 17h-28h include the minimum and maximum values, as well as every value between these values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 17h, 18h, 19h, 20h, 21h, 22h, 25h, 27h, and 28h.

[0046] Optionally, the calcination process is as follows: calcination at 3°C ​​for 3 minutes. -1 -5℃min -1 The heating rate is as follows: from room temperature to 400℃-500℃, pre-calcined for 5h-8h, then heated to 700℃-900℃ and calcined for 12h-20h.

[0047] That is, in the calcination process, the heating rate can be 3℃ / min. -1 4℃min -1 5℃min -1 At room temperature, the temperature is raised to 400℃, 450℃ or 500℃ at a certain heating rate, and pre-calcined for 5h, 6h, 7h or 8h, and then raised to 700℃, 800℃ or 900℃, and calcined for 12h, 13h, 14h, 15h, 16h, 18h, 19h or 20h.

[0048] Optionally, the metal salt includes a transition metal salt;

[0049] And / or, the precipitant includes at least one of oxalate and carbonate.

[0050] This application does not limit the metal salt, but it can be a transition metal salt, such as at least one of nickel salts, cobalt salts, and manganese salts. It is understood that the nickel salt is selected from one or more of nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate. The manganese salt is selected from one or more of manganese sulfate, manganese chloride, manganese nitrate, and manganese acetate. The cobalt salt is selected from one or more of cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate.

[0051] The precipitant can be at least one of oxalate and carbonate. It is understood that the oxalate is selected from one or more of sodium oxalate, sodium hydrogen oxalate, potassium oxalate, potassium hydrogen oxalate, ammonium oxalate, and ammonium hydrogen oxalate. The carbonate is selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate.

[0052] This application provides a cathode electrode, which includes a current collector and a coating disposed on the current collector. The coating includes a positive electrode material as described above, or the coating includes a positive electrode material prepared by the method described above.

[0053] Because other cations in the cathode material have radii larger than lithium ions, they can act as supports in the layered material, enhancing the mixing barrier and preventing intensified mixing of metal ions and lithium ions in the layered cathode. This improves the stability of the layered structure and thus enhances cycle performance. Simultaneously, other cations in the cathode material can also be intercalated into the anode material. The larger cations act as supports in graphite, reducing the expansion / contraction of graphite caused by smaller ions during intercalation / deintercalation. This improves SEI film stability, reduces active lithium consumption, and enhances cycle performance. Therefore, cathode electrodes containing the above-mentioned cathode materials exhibit high cycle performance.

[0054] Optionally, the compaction density Pd of the cathode electrode sheet satisfies the following relationship: Pd = S * K, where S is the mass ratio of the positive electrode material in the coating to the total positive electrode active material, and K is a coefficient, 0 < S ≤ 100%, 0 < K < 100.

[0055] The larger the value of S, the stronger the hierarchical energy barrier of the cathode electrode, the higher the structural stability, the stronger the compressive strength, and the higher the compressive strength of the cathode electrode can achieve.

[0056] In other words, the compaction density is directly proportional to S. The higher the compaction density, the more cathode material is required. The higher the compaction density, the smaller the gap between materials. In order to expand the gap, more other cations with radii larger than lithium are needed to support the material layer.

[0057] Optionally, S and K satisfy the following relationships: 10% < S ≤ 90%, 0 < K < 10.

[0058] Since some lithium sites in the cathode material are replaced by other cations, if the entire cathode active material is made of this cathode material, there will be a problem of lithium reduction, which will lead to a decrease in energy density. Therefore, the mass ratio of cathode material in the coating to the overall cathode active material is 10% < S ≤ 90%. In this way, the overall cathode active material also includes other active materials, such as other ternary materials, in which the lithium sites are not replaced by other elements, so as to improve the lithium capacity and thus avoid a decrease in energy density.

[0059] Optionally, the overall positive electrode active material in the coating accounts for 85%-99% of the total mass of the coating.

[0060] The overall positive electrode active material in the coating accounts for 85%-99% of the total mass of the coating. The value of 85%-99% includes the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 99%, etc.

[0061] Optionally, the compaction density of the cathode electrode ranges from 2.0 g / cm³. 3 -4.5g / cm 3 .

[0062] As compaction density increases, the bulk density of the active layer increases, porosity decreases, specific surface area increases, contact resistance decreases, and the SEI impedance and charge exchange impedance of the electrode-electrolyte interface film decrease. Lower compaction density can actually lead to lower discharge specific capacity. This is mainly because higher porosity causes some particles to form an insulating state, preventing them from participating in charge and discharge. Electrodes with higher compaction density have higher fracture strength, thus preventing electrode particles from detaching during cycling and forming insulating particles. High compaction density can significantly improve the uniformity of pore size and porosity distribution in the electrode, as well as the uniform distribution of conductive agents and binders, reducing contact resistance and charge exchange impedance, and increasing the active area that can participate in the reaction, thereby significantly improving the electrochemical performance of the material.

[0063] Therefore, a suitable compaction density is required in the cathode electrode. In this application, the compaction density of the cathode electrode is in the range of 2.0 g / cm³. 3 -4.5g / cm 3 When the compressibility of the cathode electrode is less than 2.0 g / cm³ 3 At this point, poor particle contact, poor transmission impedance, rapid lifespan decay, and failure to improve lifespan occur. When the cathode electrode compaction exceeds 4.5 g / cm³,... 3 When the interlayer pores are small, large-radius ions cannot escape. Some large ions cannot escape and embed themselves in the graphite layer, reducing expansion and leading to partial failure of the lifespan improvement.

[0064] In the cathode electrode, the compaction density ranges from 2.0 g / cm³. 3 -4.5g / cm 3 The compaction density should be set within this range to avoid both excessively low and excessively high compaction densities. This would reduce the gaps between materials, preventing some large ions from escaping and embedding into the graphite layer, thus reducing expansion and causing some failures in improving lifespan.

[0065] Optionally, the compaction density of the cathode electrode ranges from 2.8 g / cm³. 3 -3.5g / cm 3 .

[0066] The compaction density of the cathode electrode ranges from 2.8 g / cm³. 3 -3.5g / cm 3 The above 2.8g / cm 3 -3.5g / cm 3In this context, the values ​​include the minimum and maximum values ​​within the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 2.8 g / cm³. 3 2.9g / cm 3 3.0g / cm 3 3.1g / cm 3 3.2g / cm 3 3.3g / cm 3 3.4g / cm 3 3.5g / cm 3 wait.

[0067] This application also provides an electrode assembly, which includes an anode electrode, a diaphragm, and the aforementioned cathode electrode.

[0068] Optionally, the negative electrode material of the anode electrode includes at least one of graphite, hard carbon, and soft carbon.

[0069] It is understandable that the negative electrode material of the anode sheet includes at least one of graphite, hard carbon, and soft carbon.

[0070] This application also provides a battery including the electrode assembly described above.

[0071] This application also provides electrical equipment, which includes the battery described above.

[0072] The cathode material of this application comprises a layered lithium-containing metal oxide, which includes other cations with radii larger than lithium ions. These other cations, with radii greater than lithium ions, can provide support within the layered material, enhancing the mixing barrier and preventing intensified mixing of metal ions and lithium ions in the layered cathode. This improves the stability of the layered structure and thus enhances cycle performance. Simultaneously, these other cations can also be embedded into the anode material. The larger cations provide support within the graphite, reducing the expansion / contraction of graphite caused by smaller ions during embedding / extraction. This improves SEI film stability, reduces active lithium consumption, and enhances cycle performance. Attached Figure Description

[0073] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0074] Figure 1This is a schematic diagram of a method for preparing a cathode material according to this application;

[0075] Figure 2 This is a schematic diagram of an electrode assembly according to one embodiment of this application;

[0076] Figure 3 yes Figure 2 An exploded view of an electrode assembly according to an embodiment of this application is shown;

[0077] Figure 4 This is a schematic diagram of a battery module according to one embodiment of this application;

[0078] Figure 5 This is a schematic diagram of a battery pack according to one embodiment of this application;

[0079] Figure 6 yes Figure 2 An exploded view of a battery pack according to one embodiment of this application is shown;

[0080] Figure 7 This is a schematic diagram of an electrical device in which an electrode assembly according to an embodiment of this application is used as a power source.

[0081] Explanation of icon numbers:

[0082] label name label name 1 Battery pack 51 case 2 Upper box 52 Electrode assembly 3 Lower box 53 cover plate 4 Battery Module 6 Electrical appliances 5 Electrode assembly

[0083] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0084] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the electrolyte, electrode assembly, battery module, battery pack, and power supply device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0085] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60–120 and 80–110 are listed for a specific parameter, it is understood that ranges of 60–110 and 80–120 are also expected. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0086] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0087] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0088] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0089] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0090] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: 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).

[0091] In layered cathode materials, the presence of mixed lithium and metal elements results in a poor overall lifespan. For example, an increase in nickel content leads to more lithium-nickel mixing, reducing battery cycle life.

[0092] To improve the cycle life of batteries, this application provides a cathode material comprising a layered lithium-containing metal oxide, wherein the layered lithium-containing metal oxide includes other cations with radii larger than lithium ions.

[0093] Layered lithium-containing metal oxides refer to lithium-containing salts that include metal elements, such as lithium manganese oxide, lithium cobalt oxide, and lithium nickel cobalt manganese oxide.

[0094] The inclusion of other cations with radii larger than lithium ions in layered lithium-containing metal oxides means that layered lithium-containing metal oxides include not only lithium ions but also other cations with radii larger than lithium ions.

[0095] Other cations in the cathode material have radii larger than lithium ions, which can act as supports in the layered material, enhance the mixing barrier, prevent the intensification of mixing between metal ions and lithium ions in the layered cathode, improve the stability of the layered structure, and thus improve cycle performance. At the same time, other cations in the cathode material can also be inserted into the anode material. Among them, other cations with larger ionic radii act as supports in graphite, thereby reducing the expansion / contraction of graphite caused by smaller ionic ions during insertion / extraction. This is beneficial to improving the stability of the SEI film, reducing the consumption of active lithium, and improving cycle performance.

[0096] It is understandable that other cations with radii larger than lithium ions only serve to embed into the graphite layer of the negative electrode during the first charge and discharge process, forming a permanent supporting graphite layered structure. In other words, other cations with radii larger than lithium ions play a supporting role in the layered structure of the positive and negative electrode materials, so as to facilitate the insertion and extraction of lithium ions.

[0097] It is understood that the positions of other cations with radii larger than lithium ions in the layered lithium-containing metal oxide structure can be either replacing some of the positions of other ions besides lithium ions (for example, in one embodiment, the layered lithium-containing metal oxide is a nickel-cobalt-manganese-based ternary material, and other cations can replace, for example, some of the manganese positions), or replacing some of the positions of lithium ions. The specific position is not limited, and those skilled in the art can choose according to actual needs.

[0098] Further, the layered lithium-containing metal oxide includes layered lithium-containing transition metal oxide; and / or, the ionic radius of other cations is greater than 76 μm, optionally greater than 84 μm and less than 100 μm.

[0099] Layered lithium-containing metal oxides include layered lithium-containing transition metal oxides. Compared with other metals, the transition metals in layered lithium-containing transition metal oxides are more likely to mix with lithium. Including other cations with radii larger than lithium ions in layered lithium-containing transition metal oxides can effectively improve the stability of the layered structure.

[0100] The lithium ion radius is 76Pm. Cations larger than 76Pm can effectively form a supporting effect in layered materials, improve the stability of the layered structure, and thus improve cycle performance.

[0101] Furthermore, the ionic radii of other cations are greater than 84 Pm and less than 100 Pm, and the ionic radii of other cations are in the range of 84 Pm-100 Pm, so as to ensure that other cations are effectively embedded in the layered structure, which can play a supporting role in the layered material, enhance the mixing barrier, prevent the intensification of mixing between metal ions and lithium ions in the layered cathode, improve the stability of the layered structure, and thus improve the cycle performance.

[0102] Furthermore, in a layered lithium-containing metal oxide structure, the position of lithium ions is defined as a lithium site, and other cations occupy at least a portion of the lithium sites in the layered lithium-containing metal oxide structure.

[0103] In a layered lithium-containing metal oxide structure, each element has its own designated position. The position of a lithium ion in this structure is defined as a lithium site, and other cations occupy at least a portion of these lithium sites. To reduce the mixing of lithium ions with metal ions, some lithium sites in the layered cathode material are replaced with other cations that have larger ionic radii. These larger cations occupy the lithium sites stably, making further mixing unlikely, thus improving the stability of the layered structure.

[0104] Furthermore, other cationic elements include at least one of alkali metals other than lithium, alkaline earth metals, and nonmetals.

[0105] This application does not limit the types of other cations. Other cation elements include at least one of alkali metals, alkaline earth metals, and nonmetals, excluding lithium. It is understood that, theoretically, any cation with a radius larger than that of lithium ions is acceptable, but metal ions are preferred.

[0106] Furthermore, the alkali metal element includes at least one of Na, K, Rb, and Cs; the alkaline earth metal element includes at least one of Ca and Sr; and the nonmetal element includes Se.

[0107] It is understood that alkali metal elements include at least one of Na, K, Rb, and Cs; alkaline earth metal elements include at least one of Ca and Sr; and non-metallic elements include Se.

[0108] Furthermore, the general formula for layered lithium-containing metal oxides is Li x Y (2-x) Ni a Co b Mn c M (1-a-b-c) O2, Y represents other cations, and M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, and La; wherein 0.3 ≤ a < 1.0, 0 <b<0.5,0≤c≤0.2,a+b+c≤1,0<x<2。

[0109] The demand and design of layered cathode materials have evolved from early low-nickel materials to today's high-nickel materials. High-nickel materials generally have poorer lifespans. On one hand, the increased nickel content inevitably leads to more lithium-nickel mixing, reducing battery cycle life. Lithium-nickel mixing refers to the phenomenon where divalent nickel ions, whose volume is similar to that of lithium ions, occupy positions in the lithium-ion lattice when a large number of lithium ions are released during discharge, due to external factors. This ion misplacement leads to a change in the lattice type, and consequently, its lithium intercalation capability. During charging and discharging, the pressure and speed of lithium intercalation / deintercalation are greatest on the surface of the cathode material. Therefore, the surface lattice often changes due to this cation mixing phenomenon, also known as surface reconstruction. The higher the Ni content, the higher the probability of trivalent unstable nickel ions being reduced to divalent nickel ions, thus increasing the chance of cation mixing and severely reducing battery cycle life.

[0110] This application uses nickel-containing cathode materials to improve energy density. At the same time, based on the presence of other cations with radii larger than lithium ions in the cathode material, it can effectively prevent the intensification of nickel ion and lithium ion mixing in the layered cathode, improve the stability of the layered structure, and thus improve cycle performance.

[0111] Furthermore, a and b satisfy the relations: 0.6 ≤ a < 1.0, 0.3 <b<0.5。

[0112] General formula Li x Y (2-x) Ni a Co b Mn c M (1-a-b-c)In O₂, 0 < x < 2, and when x > 1, it indicates that the positive electrode material can be a lithium-rich material, such as lithium-rich manganese-based materials.

[0113] In the general formula, Li x Y (2-x) Ni a Co b Mn c M (1-a-b-c) O₂, 0.6 ≤ a < 1.0, 0.3 < b < 0.5, indicates that the positive electrode material is a high-nickel material. When it can effectively prevent the aggravation of the mixing of nickel ions and lithium ions in the layered cathode and improve the stability of the layered structure and thus the cycle performance, using a high-nickel material can effectively improve the energy density.

[0114] Furthermore, 0 < x < 1.

[0115] When 0 < x < 1, the positive electrode material can be a ternary material. Among the transition metals in the ternary material, it is easier to mix with lithium compared to other metals. At this time, 0 < x < 1, indicating that in the general formula Li x Y (2-x) Ni a Co b Mn c M (1-a-b-c) O₂, the content of other cations represented by Y increases. The increase in the content of other cations is beneficial to increasing the mixing energy barrier, preventing the aggravation of the mixing of transition metal ions and lithium ions in the layered cathode, and improving the stability of the layered structure and thus the cycle performance.

[0116] Furthermore, the present application provides a method for preparing a positive electrode material, including the following steps: adding a metal salt to a solvent, stirring to obtain a metal salt solution; adding a precipitating agent to the metal salt solution to obtain a precursor; mixing the precursor, a lithium salt, and a salt of other cations, and calcining to obtain a layered lithium-containing metal oxide; wherein, the radius of the other cations in the salt of other cations is greater than the radius of lithium ions.

[0117] As Figure 1 shown, it is a schematic flow chart of a method for preparing a positive electrode material according to the present application. Adding a metal salt to a solvent, stirring to obtain a metal salt solution; adding a precipitating agent to the metal salt solution to obtain a precursor; mixing the precursor, a lithium salt, and a salt of other cations, and calcining to obtain a layered lithium-containing metal oxide; wherein, the radius of the other cations in the salt of other cations is greater than the radius of lithium ions.

[0118] Using a precipitating agent to precipitate the metal salt to obtain a precursor, mixing the precursor with a lithium salt and a salt of other cations, and grinding and calcining to obtain a layered lithium-containing metal oxide, wherein, the radius of the other cations in the salt of other cations is greater than the radius of lithium ions.

[0119] Understandably, during the calcination process of mixing the precursor, lithium salt, and other cation salts, the mixed components can be ground before calcination. The grinding method is not limited and can include milling, grinding, ball milling, etc. This grinding step ensures that the prepared cathode material has a uniform structure and stable performance.

[0120] Other cations in the cathode material have radii larger than lithium ions, which can act as supports in the layered material, enhance the mixing barrier, prevent the intensification of mixing between metal ions and lithium ions in the layered cathode, improve the stability of the layered structure, and thus improve cycle performance. At the same time, other cations in the cathode material can also be inserted into the anode material. Among them, other cations with larger ionic radii act as supports in graphite, thereby reducing the expansion / contraction of graphite caused by smaller ionic ions during insertion / extraction. This is beneficial to improving the stability of the SEI film, reducing the consumption of active lithium, and improving cycle performance.

[0121] Understandably, lithium salts are selected from one or more of lithium sulfate, lithium chloride, lithium nitrate, lithium acetate, lithium carbonate, and lithium hydroxide.

[0122] It is understandable that metal salts are added to a solvent, which may include water.

[0123] Furthermore, the radii of other cations are greater than 76 Pm.

[0124] The lithium ion radius is 76Pm. Cations larger than 76Pm can effectively form a supporting effect in layered materials, improve the stability of the layered structure, and thus improve cycle performance.

[0125] Furthermore, in a layered lithium-containing metal oxide structure, the position of lithium ions is defined as a lithium site, and other cations occupy at least a portion of the lithium sites in the layered lithium-containing metal oxide structure.

[0126] In a layered lithium-containing metal oxide structure, each element has its own designated position. The position of a lithium ion in this structure is defined as a lithium site, and other cations occupy at least a portion of these lithium sites. To reduce the mixing of lithium ions with metal ions, some lithium sites in the layered cathode material are replaced with other cations that have larger ionic radii. These larger cations occupy the lithium sites stably, making further mixing unlikely, thus improving the stability of the layered structure.

[0127] Furthermore, the general formula for layered lithium-containing metal oxides is Li x Y (2-x) Ni a Co b Mn c M (1-a-b-c)O2, Y represents other cations, and M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, and La; wherein 0.3 ≤ a < 1.0, 0 <b<0.5,0≤c≤0.2,a+b+c≤1,0<x<2。

[0128] This application uses nickel-containing cathode materials to improve energy density. At the same time, based on the presence of other cations with radii larger than lithium ions in the cathode material, it can effectively prevent the intensification of nickel ion and lithium ion mixing in the layered cathode, improve the stability of the layered structure, and thus improve cycle performance.

[0129] Furthermore, the types of salts of other cations include at least one of alkali metal salts, alkaline earth metal salts, and nonmetal salts.

[0130] This application does not limit the types of salts of other cations, but the types of salts of other cations include at least one of alkali metal salts, alkaline earth metal salts, and non-metal salts. It is understood that, theoretically, any element with a radius larger than that of the lithium ion can be used, with metal ions being preferred.

[0131] Furthermore, the step of adding a precipitant to a metal salt solution to obtain a precursor includes the following steps: adding a precipitant to a metal salt solution, reacting for 3-20 hours, aging for 2-12 hours to obtain the precursor.

[0132] It is understandable that the reaction time of 3-20 hours is for generating primary particles. Since particle breakage occurs during the reaction process, aging for 2-12 hours can help repair and grow the crystal lattice of the primary particles.

[0133] The values ​​in the range 3h-20h include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 3h, 5h, 8h, 10h, 14h, 16h, 18h, 20h, etc.

[0134] The values ​​in the range 2h-12h include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 2h, 3h, 5h, 8h, 10h, 12h, etc.

[0135] Furthermore, the step of adding a precipitant to the metal salt solution to obtain the precursor also includes the following steps: adding a precipitant to the metal salt solution, reacting for 3-20 hours, aging for 2-12 hours, washing and drying the product to obtain the precursor.

[0136] During the preparation of the precursor, impurities are removed through a cleaning step to avoid impurities in the final cathode material, which could affect battery performance. It is understood that the drying temperature is 100℃-140℃, and the drying time is 12h-24h. For example, the product is washed three times with deionized water, dried in a blower dryer, and then vacuum-dried at 100℃ for 12h. The collected solid is the precursor.

[0137] Furthermore, in the step of mixing the precursor, lithium salt, and other cation salts and calcining to obtain layered lithium-containing metal oxides, the molar ratio of the precursor, lithium salt, and other cation salts is defined as P:Q:R, which satisfies (Q+R) / P≥1.07.

[0138] The excess lithium salt and other cation salts are used to compensate for the loss of lithium and other cations during high-temperature calcination. Therefore, in the step of mixing the precursor, lithium salt and other cation salts, calcining, and obtaining layered lithium metal oxide, the lithium salt and other cation salts are added in excess. That is, if the molar ratio of the precursor, lithium salt and other cation salts is defined as P:Q:R, then (Q+R) / P≥1.07 is satisfied.

[0139] Furthermore, the calcination time is 17-28 hours.

[0140] During calcination, lithium and other cationic elements can be incorporated into the precursor material's lattice more quickly and uniformly, thereby maximizing the doping effect of each dopant element. The values ​​within the range of 17h-28h include the minimum and maximum values, as well as every value between these values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 17h, 18h, 19h, 20h, 21h, 22h, 25h, 27h, and 28h.

[0141] Furthermore, the calcination procedure is as follows: at 3℃ for 3 minutes... -1 -5℃min -1 The heating rate is as follows: from room temperature to 400℃-500℃, pre-calcined for 5h-8h, then heated to 700℃-900℃ and calcined for 12h-20h.

[0142] That is, in the calcination process, the heating rate can be 3℃ / min. -1 4℃min -1 5℃min -1 At room temperature, the temperature is raised to 400℃, 450℃ or 500℃ at a certain heating rate, and pre-calcined for 5h, 6h, 7h or 8h, and then raised to 700℃, 800℃ or 900℃, and calcined for 12h, 13h, 14h, 15h, 16h, 18h, 19h or 20h.

[0143] Furthermore, the metal salt includes transition metal salts; and / or, the precipitant includes at least one of oxalate and carbonate.

[0144] This application does not limit the metal salt, but it can be a transition metal salt, such as at least one of nickel salts, cobalt salts, and manganese salts. It is understood that the nickel salt is selected from one or more of nickel sulfate, nickel chloride, nickel nitrate, and nickel acetate. The manganese salt is selected from one or more of manganese sulfate, manganese chloride, manganese nitrate, and manganese acetate. The cobalt salt is selected from one or more of cobalt sulfate, cobalt chloride, cobalt nitrate, and cobalt acetate.

[0145] The precipitant can be at least one of oxalate and carbonate. It is understood that the oxalate is selected from one or more of sodium oxalate, sodium hydrogen oxalate, potassium oxalate, potassium hydrogen oxalate, ammonium oxalate, and ammonium hydrogen oxalate. The carbonate is selected from one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, ammonium carbonate, and ammonium bicarbonate.

[0146] Furthermore, this application provides a cathode electrode, which includes a current collector and a coating disposed on the current collector. The coating includes the positive electrode material as described above, or the coating includes the positive electrode material prepared by the method described above.

[0147] Since the cathode material adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0148] Because other cations in the cathode material have radii larger than lithium ions, they can act as supports in the layered material, enhancing the mixing barrier and preventing intensified mixing of metal ions and lithium ions in the layered cathode. This improves the stability of the layered structure and thus enhances cycle performance. Simultaneously, other cations in the cathode material can also be intercalated into the anode material. The larger cations act as supports in graphite, reducing the expansion / contraction of graphite caused by smaller ions during intercalation / deintercalation. This improves SEI film stability, reduces active lithium consumption, and enhances cycle performance. Therefore, cathode electrodes containing the above-mentioned cathode materials exhibit high cycle performance.

[0149] Furthermore, the compaction density Pd of the cathode electrode sheet satisfies the following relationship: Pd=S*K, where S is the mass ratio of the positive electrode material in the coating to the total positive electrode active material, and K is a coefficient, 0<S≤100%, 0<K<100.

[0150] The compaction density Pd of the cathode electrode sheet satisfies the following relationship: Pd=S*K, where S is the mass ratio of the positive electrode material in the coating to the total positive electrode active material, and K is a coefficient, 0<S≤100%, 0<K<100.

[0151] The larger the value of S, the stronger the hierarchical energy barrier of the cathode electrode, the higher the structural stability, the stronger the compressive strength, and the higher the compressive strength of the cathode electrode can achieve.

[0152] In other words, the compaction density is directly proportional to S. The higher the compaction density, the more cathode material is required. The higher the compaction density, the smaller the gap between materials. In order to expand the gap, more other cations with radii larger than lithium are needed to support the material layer.

[0153] In the above 0<S≤100%, the values ​​include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.5%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, etc.

[0154] In the above 0 < K < 100, the values ​​include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.5, 1, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 99, etc.

[0155] Furthermore, S and K satisfy the following relationships: 10% < S ≤ 90%, 0 < K < 10.

[0156] Since some lithium sites in the cathode material are replaced by other cations, if the entire cathode active material is made of this cathode material, there will be a problem of lithium reduction, which will lead to a decrease in energy density. Therefore, the mass ratio of cathode material in the coating to the overall cathode active material is 10% < S ≤ 90%. In this way, the overall cathode active material also includes other active materials, such as other ternary materials, in which the lithium sites are not replaced by other elements, so as to improve the lithium capacity and thus avoid a decrease in energy density.

[0157] When the mass ratio of the cathode material to the total cathode active material is 10% < S ≤ 90%, that is, the doping amount is > 10%, the amount of large-radius ions in the cathode material is sufficient to support the interlayer of the cathode material, and the excess ions can be extracted and embedded in the graphite to reduce expansion.

[0158] In the above 10% < S ≤ 90%, the values ​​include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 11%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.

[0159] In the above 0 < K < 10, the values ​​include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, etc.

[0160] Furthermore, the overall positive electrode active material in the coating accounts for 85%-99% of the total mass of the coating.

[0161] The overall positive electrode active material in the coating accounts for 85%-99% of the total mass of the coating. The value of 85%-99% includes the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 99%, etc.

[0162] Furthermore, the compaction density of the cathode electrode ranges from 2.0 g / cm³. 3 -4.5g / cm 3 .

[0163] A cathode electrode includes a current collector and a positive electrode material disposed on the current collector.

[0164] Compacted density, compacted density = areal density / (thickness of electrode after compaction - thickness of current collector), unit: g / cm³ 3 .

[0165] As compaction density increases, the bulk density of the active layer increases, porosity decreases, specific surface area increases, contact resistance decreases, and the SEI impedance and charge exchange impedance of the electrode-electrolyte interface film decrease. Lower compaction density can actually lead to lower discharge specific capacity. This is mainly because higher porosity causes some particles to form an insulating state, preventing them from participating in charge and discharge. Electrodes with higher compaction density have higher fracture strength, thus preventing electrode particles from detaching during cycling and forming insulating particles. High compaction density can significantly improve the uniformity of pore size and porosity distribution in the electrode, as well as the uniform distribution of conductive agents and binders, reducing contact resistance and charge exchange impedance, and increasing the active area that can participate in the reaction, thereby significantly improving the electrochemical performance of the material.

[0166] Therefore, a suitable compaction density is required in the cathode electrode. In this application, the compaction density of the cathode electrode is in the range of 2.0 g / cm³. 3 -4.5g / cm 3 When the compressibility of the cathode electrode is less than 2.0 g / cm³ 3 At this point, poor particle contact, poor transmission impedance, rapid lifespan decay, and failure to improve lifespan occur. When the cathode electrode compaction exceeds 4.5 g / cm³,... 3 When the interlayer pores are small, large-radius ions cannot escape. Some large ions cannot escape and embed themselves in the graphite layer, reducing expansion and leading to partial failure of the lifespan improvement.

[0167] In the cathode electrode, the compaction density ranges from 2.0 g / cm³. 3 -4.5g / cm 3 The compaction density should be set within this range to avoid both excessively low and excessively high compaction densities. This would reduce the gaps between materials, preventing some large ions from escaping and embedding into the graphite layer, thus reducing expansion and causing some failures in improving lifespan.

[0168] It is understandable that the compaction density of the cathode electrode is in the range of 2.0 g / cm³. 3 -4.5g / cm 3 The above 2.0 g / cm 3 -4.5g / cm 3 In this context, the values ​​include the minimum and maximum values ​​within the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 2.0 g / cm³. 3 2.2g / cm 3 2.4g / cm 3 2.8g / cm 3 2.9g / cm 3 3.0g / cm 3 3.1g / cm 3 3.2g / cm 3 3.3g / cm 3 3.4g / cm 3 3.5g / cm 3 3.6g / cm 3 3.7g / cm 3 3.8g / cm 3 3.9g / cm 3 4.0g / cm 3 4.2g / cm 3 4.4 g / cm 3 4.5g / cm 3 wait.

[0169] Furthermore, the preferred compaction density range for the cathode electrode is 2.8 g / cm³. 3 -3.5g / cm 3 .

[0170] The compaction density of the cathode electrode ranges from 2.8 g / cm³. 3 -3.5g / cm 3 The above 2.8g / cm 3 -3.5g / cm 3 In this context, the values ​​include the minimum and maximum values ​​within the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments and 2.8 g / cm³. 3 2.9g / cm 3 3.0g / cm 3 3.1g / cm 3 3.2g / cm 3 3.3g / cm 3 3.4g / cm 3 3.5g / cm 3 wait.

[0171] Furthermore, this application also provides an electrode assembly, which includes an anode electrode, a diaphragm, and the aforementioned cathode electrode.

[0172] Since the cathode electrode adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0173] Furthermore, the negative electrode material of the anode sheet includes at least one of graphite, hard carbon, and soft carbon.

[0174] It is understandable that the negative electrode material of the anode sheet includes at least one of graphite, hard carbon, and soft carbon.

[0175] Furthermore, this application also provides a battery including the electrode assembly described above.

[0176] Since the electrode assembly adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0177] Furthermore, this application also provides an electrical device, which includes the battery described above.

[0178] Since the battery adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be repeated here.

[0179] In addition, the electrode assembly, battery (including battery module and battery pack) and power device of this application will be described below with appropriate reference to the accompanying drawings.

[0180] In one embodiment of this application, an electrode assembly is provided.

[0181] Typically, an electrode assembly includes a cathode electrode, an anode electrode, an electrolyte, and a separator. During battery charging and discharging, active ions move back and forth between the cathode and anode electrodes, inserting and extracting. The electrolyte acts as a conductor of ions between the cathode and anode electrodes. The separator, positioned between the cathode and anode electrodes, primarily prevents short circuits between the positive and negative electrodes while allowing ions to pass through. The separator described above is the improved separator of this application.

[0182] The cathode electrode includes a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector.

[0183] As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0184] In some embodiments, the positive current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0185] In some embodiments, when the electrode assembly is a lithium-ion battery, the positive electrode active material may be a positive electrode active material known in the art for lithium-ion batteries. As an example, the positive electrode active material may include at least one of the following materials: lithium phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include, but are not limited to, lithium cobalt oxides (such as LiCoO2), lithium nickel oxides (such as LiNiO2), lithium manganese oxides (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxides, lithium manganese cobalt oxides, lithium nickel manganese oxides, and lithium nickel cobalt manganese oxides (such as LiNi). 1 / 3 Co 1 / 3Mn 1 / 3 O2 (also known as NCM)333 LiNi 0.5 Co 0.2 Mn 0.3 O2 (also known as NCM) 523 LiNi 0.5 Co 0.25 Mn 0.25 O2 (also known as NCM) 211 LiNi 0.6 Co 0.2 Mn 0.2 O2 (also known as NCM) 622 LiNi 0.8 Co 0.1 Mn 0.1 O2 (also known as NCM) 811 ), lithium nickel cobalt aluminum oxide (such as LiNi) 0.85 Co 0.15 Al 0.05 At least one of O2 and its modified compounds. Examples of lithium phosphates with an olivine structure include, but are not limited to, lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0186] In some embodiments, the positive electrode film layer may optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0187] In some embodiments, the positive electrode film may optionally include a conductive agent. As an example, the conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0188] In some embodiments, the cathode electrode can be prepared by dispersing the above-mentioned components for preparing the cathode electrode, such as positive electrode active material, conductive agent, binder and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry onto a positive electrode current collector, and then obtaining the cathode electrode after drying, cold pressing and other processes.

[0189] The anode plate includes a negative current collector and a negative electrode film layer disposed on at least one surface of the negative current collector, the negative electrode film layer including a negative electrode active material.

[0190] As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0191] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0192] In some embodiments, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc. Silicon-based materials may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys. However, this application is not limited to these materials, and other conventional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0193] In some embodiments, the negative electrode film layer may optionally include a binder. The binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0194] In some embodiments, the negative electrode film may optionally include a conductive agent. The conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0195] In some embodiments, the negative electrode film may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0196] In some embodiments, the anode electrode can be prepared by dispersing the above-mentioned components for preparing the anode electrode, such as negative electrode active material, conductive agent, binder and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry; coating the negative electrode slurry onto a negative electrode current collector, and then obtaining the anode electrode after drying, cold pressing and other processes.

[0197] The electrolyte acts as a conductor of ions between the cathode and anode electrodes. This application does not specify any particular type of electrolyte; it can be selected according to requirements.

[0198] In some embodiments, the electrolyte is an electrolyte solution. The electrolyte solution includes an electrolyte salt and a solvent.

[0199] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium dioxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0200] In some embodiments, the solvent may be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butyl carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0201] In some embodiments, the electrolyte may optionally include additives. For example, additives may include negative electrode film-forming additives, positive electrode film-forming additives, and may also include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature or low-temperature performance, etc.

[0202] In some embodiments, the electrode assembly also includes a diaphragm. This application does not impose any particular limitation on the type of diaphragm; any known porous diaphragm with good chemical and mechanical stability can be selected.

[0203] In some embodiments, the diaphragm material can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The diaphragm can be a single-layer film or a multi-layer composite film, without particular limitation. When the diaphragm is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0204] In some implementations, the cathode electrode, anode electrode, and separator can be fabricated into an electrode assembly using a winding process or a stacking process.

[0205] In some embodiments, the electrode assembly may include an outer packaging. This outer packaging can be used to encapsulate the electrode assembly and the electrolyte.

[0206] In some embodiments, the outer packaging of the electrode assembly can be a rigid shell, such as a hard plastic shell, an aluminum shell, or a steel shell. The outer packaging of the electrode assembly can also be a flexible package, such as a pouch. The material of the flexible package can be plastic; examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0207] This application does not impose any particular limitation on the shape of the electrode assembly; it can be cylindrical, square, or any other arbitrary shape. For example, Figure 2 Here is an example of a square-structured electrode assembly 5.

[0208] In some implementations, refer to Figure 3 The outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates forming a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 can be placed over the opening to close the receiving cavity. The cathode electrode, anode electrode, and diaphragm may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is encapsulated within the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The electrode assembly 52 may contain one or more electrode assemblies, which can be selected by those skilled in the art according to specific practical needs.

[0209] In some embodiments, the electrode assemblies can be assembled into a battery module, and the number of electrode assemblies contained in the battery module can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0210] Figure 4 This is battery module 4, used as an example. (See reference...) Figure 4 In battery module 4, multiple electrode assemblies 5 can be arranged sequentially along the length of battery module 4. Of course, they can also be arranged in any other manner. Furthermore, these multiple electrode assemblies 5 can be fixed in place using fasteners.

[0211] Optionally, the battery module 4 may also include a housing with a receiving space in which a plurality of electrode assemblies 5 are received.

[0212] In some embodiments, the battery modules described above can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, the specific number of which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0213] Figure 5 and Figure 6This is battery pack 1 as an example. (See reference...) Figure 5 and Figure 6 The battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3, with the upper body 2 covering the lower body 3 to form a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0214] In addition, this application also provides an electrical device, which includes at least one of the electrode assembly, battery module, or battery pack provided in this application. The electrode assembly, battery module, or battery pack can be the power source of the electrical device or the energy storage unit of the electrical device. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0215] As an electrical device, electrode components, battery modules, or battery packs can be selected according to their usage requirements.

[0216] Figure 7 This is an example of an electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the electrode components, a battery pack or battery module can be used.

[0217] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a thin and light design and may use electrode components as a power source.

[0218] Example

[0219] Example 1

[0220] Cathode material Li 0.5 Na 0.1 K 0.2 Cs 0.05 Rb 0.15 Ni 0.5 Co 0.2 Mn 0.3 O2 preparation

[0221] First, nickel acetate, cobalt acetate, and manganese acetate were added to deionized water in a stoichiometric ratio of 5:2:3 and stirred until homogeneous. The sodium carbonate solution was then quickly poured into the transition metal salt solution, and the reaction continued for 9 hours. The mixture was then allowed to stand for 4 hours to allow for primary particle growth. The mixture was washed three times with deionized water, dried in a blower dryer, and then vacuum-dried at 100°C for 12 hours. The collected solid was the precursor.

[0222] The precursor was mixed evenly with lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, and rubidium carbonate in a molar ratio of 1:0.535:0.107:0.216:0.0535:0.1605, and then ground. Excess lithium carbonate was added to compensate for lithium loss during high-temperature calcination. The thoroughly ground solid powder was transferred to a crucible and calcined in a muffle furnace with a programmed temperature rise. The calcination program was as follows: pre-calcination at 500℃ for 5 hours from room temperature, followed by calcination at 800℃ for 12 hours, with a heating rate of 3℃ / min. -1 Li was then collected after cooling to room temperature. 0.5 Na 0.1 K 0.2 Cs 0.05 Rb 0.15 Ni 0.5 Co 0.2 Mn 0.3 O2 materials.

[0223] Preparation of the cathode electrode for a secondary battery: Polyvinylidene fluoride (PVDF), positive electrode material, and conductive agent (carbon black SuperP) are mixed in a mass ratio of 90:5:5. N-methyl-pyrrolidone (NMP) is used as the solvent, and the amount of solvent added is adjusted to control the slurry viscosity at 100-20000 mPa·s. The slurry is then coated onto the cathode current collector using a coating machine or sprayer. After drying at 85℃, cold pressing is performed, and the compaction of the cathode electrode is set to 2.9 g / cm³. 3 Then, the edges are cut, the pieces are cut, and the pieces are slit. The pieces are then dried under vacuum at 85°C for 4 hours, and the tabs are welded to produce a secondary battery cathode sheet that meets the requirements.

[0224] Based on Example 1, the type of positive electrode material, the proportion of positive electrode material in the active material, and the compaction density of the cathode electrode were changed to obtain Examples 2 to 9, and Comparative Examples 1 to 3. The specific parameters are shown in Table 1.

[0225] Electrical performance characterization

[0226] Cyclic performance test:

[0227] The cycle test conditions are as follows: the secondary battery is subjected to 1C / 1C cycle test at 25℃ and 45℃, with a charge / discharge voltage range of 2.8~4.35V. The test is stopped when the capacity decays to 80% of the initial discharge specific capacity.

[0228] Table 1. Parameters related to the embodiment

[0229]

[0230]

[0231]

[0232] In summary, the incorporation of larger radius ions into the cathode material limits its cathode compaction to 2.0 g / cm³. 3 -4.5g / cm 3 This is beneficial for significantly improving battery cycle performance. On the one hand, the doping of larger-radius ions helps stabilize the layered structure of the cathode, reducing material loss. On the other hand, the larger-radius ions are embedded in the graphite material through the electrolyte containing the ion salt, supporting the graphite layered structure, reducing active lithium loss, and improving cycle performance.

[0233] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. A cathode electrode, characterized by, The cathode pole piece comprises a current collector and a coating layer arranged on the current collector, the coating layer comprises a positive electrode material, the positive electrode material comprises a layered lithium-containing metal oxide, the layered lithium-containing metal oxide comprises other cations with a larger ionic radius than lithium ions; The mass ratio of the positive electrode material in the coating layer to the total positive electrode active material in the coating layer is S, and S satisfies 50%≤S≤100%; The compacted density of the cathode electrode ranges from 2.0 g / cm 3 - 4.5 g / cm 3 .

2. The cathode electrode plate of claim 1, wherein, The layered lithium-containing metal oxide comprises a layered lithium-containing transition metal oxide; and / or, The ionic radius of the other cations is greater than 76Pm.

3. The cathode electrode plate of claim 2, wherein The ionic radius of the other cations is greater than 84Pm and less than 100Pm.

4. The cathode electrode plate of any one of claims 1 to 3, wherein In the structure of the layered lithium-containing metal oxide, the positions of the lithium ions are defined as lithium sites, and the other cations occupy at least part of the lithium sites in the structure of the layered lithium-containing metal oxide.

5. The cathode electrode plate of any one of claims 1 to 4, wherein The other cation elements comprise at least one of alkali metal elements, alkaline earth metal elements, and non-metal elements other than lithium elements.

6. The cathode electrode plate of claim 5, wherein the binder is present in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the active material. The alkali metal elements comprise at least one of Na, K, Rb, and Cs; The alkaline earth metal elements comprise at least one of Ca and Sr; The non-metal elements comprise Se.

7. The cathode electrode plate of any one of claims 1 to 5, wherein, The general formula of the layered lithium-containing metal oxide is Li x Y （2-x） Ni a Co b Mn c M (1-a-b-c) O2, Y represents the other cation, M includes at least one of Mg, Zr, Al, B, Ta, Mo, W, Nb, Sb, La; wherein, 0.3≤a<1.0, 0<b<0.5, 0≤c≤0.2, a+b+c≤1, 0<x<2.

8. The cathode electrode plate of claim 7, wherein the binder is present in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the active material. 0.6≤a<1.0, 0.3<b<0.

5.

9. The cathode electrode sheet according to claim 7 or 8, wherein 0<x<1。 10. The cathode electrode plate of any one of claims 1 to 9, wherein, The total positive electrode active material in the coating layer accounts for 85%-99% of the total mass of the coating layer.

11. The cathode electrode plate of any one of claims 1 to 10, wherein The compacted density of the cathode electrode ranges from 2.8 g / cm 3 - 3.5 g / cm 3 .

12. A method of producing the cathode sheet according to any one of claims 1 to 11, characterized by, The positive electrode material is prepared by the following steps: A metal salt is added to a solvent, stirred to obtain a metal salt solution; A precipitating agent is added to the metal salt solution to obtain a precursor; The precursor, a lithium salt, and a salt of other cations are mixed and calcined to obtain a layered lithium-containing metal oxide; The radius of the other cations in the salt of the other cations is greater than the radius of lithium ions.

13. The method of producing a cathode electrode sheet according to claim 12, wherein The type of the salt of the other cations comprises at least one of an alkali metal salt, an alkaline earth metal salt, and a non-metal salt.

14. The method of producing a cathode electrode sheet according to claim 12 or 13, characterized by, In the step of adding a precipitating agent to the metal salt solution to obtain a precursor, The following steps are included; A precipitating agent is added to the metal salt solution, reacted for 3h-20h, aged for 2h-12h, and a precursor is obtained.

15. The method of producing a cathode electrode sheet according to any one of claims 12 to 14, wherein In the step of mixing the precursor, a lithium salt, and a salt of other cations, and calcining to obtain a layered lithium-containing metal oxide, the molar ratio of the precursor, the lithium salt, and the salt of other cations is defined as P:Q:R, and (Q+R) / P≥1.07 is satisfied.

16. The method of producing a cathode electrode sheet according to any one of claims 12 to 15, wherein The calcination time of the calcination process is 17h-28h.

17. The method of producing a cathode electrode sheet according to any one of claims 12 to 16, wherein The calcination procedure of the calcination process is: increasing the temperature from room temperature to 400-500°C at a rate of 3°C min -1 -5°C min -1 and pre-calcining for 5-8 h, then increasing the temperature to 700-900°C and calcining for 12-20 h.

18. The method of producing a cathode electrode sheet according to any one of claims 12 to 17, wherein The metal salt comprises a transition metal salt; And / or, the precipitating agent comprises at least one of an oxalate and a carbonate.

19. An electrode assembly, characterized by, The electrode assembly comprises an anode pole piece, a separator, and the cathode pole piece of any one of claims 1-11.

20. The electrode assembly of claim 19, wherein, The negative electrode material of the anode pole piece comprises at least one of graphite, hard carbon, and soft carbon.

21. A battery, characterized by The electrode assembly as claimed in claim 19 or 20 is included.

22. An electrical device, comprising: The electric device comprises the battery of claim 21.

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