Positive active material, positive electrode plate, electrochemical energy storage device, and apparatus

Abstract

Electrochemical energy storage device, wherein the electrochemical energy storage device comprises positive active material and negative active material, wherein the positive active material is a ternary material comprising Ni, Co and M, wherein the ratio of nickel, cobalt and manganese is y:z:k, y+z+k=1, 0.7 ≤ y ≤ 0.9, and M is selected from one or two of the elements Mn and Al. where the particle size D n 10 of the positive active material 0.3 µm ≤ D n 10 ≤ 2 µm is fulfilled, where the particle size D v 10 of the positive active material 0.5 µm ≤ D v 10 ≤ 3 µm fulfilled; where D n 10 a corresponding particle size is when a cumulative number distribution percentage of the positive active substance reaches 10%, where D v 10 a corresponding particle size is when a cumulative volume distribution percentage of the positive active substance reaches 10%.

Description

TECHNICAL AREA

[0001] This application relates to the field of electrochemical technologies, in particular a positive active material, a positive electrode plate, an electrochemical energy storage device and a device. BACKGROUND

[0002] In light of the ever-worsening energy crisis and environmental problems, the development of new green energy sources has become urgently necessary. Lithium-ion batteries are finding widespread application in various sectors due to their advantages, such as high specific energy, wide operating temperature range, low self-discharge rate, long lifespan, good safety performance, and environmental friendliness. Furthermore, there is a gradual global effort to replace conventional diesel vehicles with new energy vehicles that utilize lithium-ion batteries as their power system. However, currently, commonly used positive active materials such as lithium iron phosphate (LiFePO4) and low-nickel ternary materials (LiNi1 / 3Co1 / 3Mn1 / 3O2) cannot fully meet the energy density requirements of lithium-ion batteries due to their inherent properties.The energy density of lithium-ion batteries can be improved by increasing the nickel content of the ternary material. Therefore, high-nickel ternary materials are currently one of the main research targets in the field of positive active materials for lithium-ion batteries. However, with increasing nickel content, the side reactions between the ternary material and the electrolyte solution also increase significantly, leading to substantial gas formation in the lithium-ion batteries. This is currently one of the biggest bottlenecks in the commercial mass production of high-nickel ternary materials.

[0003] Currently, methods for mitigating the gas formation problem in lithium-ion batteries at the material level mainly involve reducing the nickel content in the ternary material and washing to reduce the residual lithium content on the surface of the positive active material. However, these methods all negatively impact the performance of lithium-ion batteries to varying degrees, for example, by reducing the reversible capacity per gram and degrading the cycle performance of the lithium-ion batteries.

[0004] Therefore, effective technical processes are needed to give lithium-ion batteries a higher energy density so that they can meet increasingly stringent application requirements, while at the same time reducing the gas evolution of lithium-ion batteries and improving the storage performance of lithium-ion batteries. BRIEF SUMMARY

[0005] In light of the existing problems, one objective of this application is to provide a positive active material, a positive electrode plate, an electrochemical energy storage device, and a device. This application can effectively reduce side reactions between the positive active material and an electrolyte solution, decrease gas evolution from the electrochemical energy storage device, and improve the storage performance of the electrochemical energy storage device without compromising its energy density, cycle time, and overall efficiency.

[0006] To achieve the aforementioned objective, one aspect of this application provides for positive active material. The positive active material is Li x Ni y Co z M k Me p O r A m or Li x Ni y Co z M k Mep O r A m with a coating layer on its surface, where 0.85 ≤ x ≤ 1.15, 0 <y<1, 0<z<1, 0<k<1, 0≤p≤0,1, 1≤r≤2, 0≤m≤1, m+r≤2, M aus einem oder zwei der Elemente Mn und Al ausgewählt ist, Me aus einem oder mehreren der Elemente Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, und Nb ausgewählt, und A wird aus einem oder mehreren von N, F, S und Cl ausgewählt. Das positive aktive Material besteht aus Einkristall- oder Quasi-Einkristallpartikeln, und eine Partikelgröße Dn10 des positiven aktiven Materials erfüllt: 0,3 µm ≤ Dn10 ≤ 2 µm.

[0007] According to another aspect of this application, this application provides a positive electrode plate, wherein the positive electrode plate comprises the positive active material in one aspect of this application.

[0008] According to another aspect of this application, this application provides an electrochemical energy storage device, wherein the electrochemical energy storage device comprises the positive active material in another aspect of this application.

[0009] According to another aspect of this application, this application provides a device, wherein the device is a vehicle and, in another aspect of this application, includes the electrochemical energy storage device.

[0010] The beneficial effects of this application include the following:

[0011] In this application, the particle morphology of the positive active material and the amount of micropowder in the positive active material are appropriately controlled to effectively reduce side reactions between the positive active material and the electrolyte solution, decrease gas evolution from the electrochemical energy storage device, and improve the storage performance of the electrochemical energy storage device without compromising its energy density, cycle time, and overall efficiency. The device in this application incorporates the electrochemical energy storage device and therefore offers at least the same advantages. BRIEF DESCRIPTION OF THE DRAWINGS Fig.1 is a particle size distribution curve based on a difference volume of a positive active material in comparative example 1 of this application; Fig. 2 is a particle size distribution curve based on the difference number of a positive active material in comparative example 1 of this application; Fig. 3 is a particle size distribution curve based on the difference volume of a positive active material in Example 3 of this application; Fig. 4 is a particle size distribution curve based on a difference number of a positive active material in Example 3 of this application; Fig. Figure 5 is a perspective view of an embodiment of an electrochemical energy storage device; Fig. Figure 6 is a perspective view of an embodiment of a battery module; Fig.Figure 7 is a perspective view of an embodiment of a battery pack; Fig. Figure 8 is an exploded view of Fig. 7; and Fig. Figure 9 is a schematic diagram of an embodiment of a device that uses an electrochemical energy storage device as a power supply. Description of the reference symbols: 1 battery pack; 2 Upper housing body; 3 Lower housing body; 4 battery modules; and 5 Electrochemical energy storage device. DESCRIPTION OF THE EXECUTION FORMS

[0012] The following section describes in detail a positive active material and manufacturing process, a positive electrode plate, an electrochemical energy storage device, and a device used in this application.

[0013] First, the positive active material is described in accordance with the first aspect of this application.

[0014] The positive active material according to the first aspect of this application is Li x Ni y Co z M k Me p O r A m or Li x Ni y Co z M k Me p O r A m with a coating layer on its surface, where 0.85 ≤ x ≤ 1.15, 0 <y<1, 0<z<1, 0<k<1, 0≤p≤0,1, 1≤r≤2, 0≤m≤1, m+r ≤ 2, M aus einem oder zwei der Elemente Mn und Al ausgewählt ist, Me aus einem oder mehreren der Elemente Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W, und Nb ausgewählt, und A wird aus einem oder mehreren von N, F, S und Cl ausgewählt.

[0015] In the actual manufacturing process of a ternary material, melting, decomposition, and evaporation losses can occur due to problems with potential impurities and the low melting point of the lithium salt used as raw material at relatively low temperatures. Therefore, excess lithium salt is added during the ternary material manufacturing process to compensate for the lithium loss caused during sintering. The surface of the ternary material exhibits reactive oxygen anions that react with CO₂ and H₂O in the air to form carbonate. Simultaneously, lithium ions migrate from the body to the surface, forming Li₂CO₃ on the surface of the ternary material. This process is accompanied by the formation of a distorted surface oxide layer resulting from the deoxidation of the ternary material's surface.Furthermore, the addition of excess lithium salt during the synthesis of the ternary material results in the main products of the excess lithium salt, which is calcined at high temperature, being lithium oxides. These lithium oxides react with CO₂ and H₂O in the air to form LiOH and Li₂CO₃, which remain on the surface of the ternary material, leading to a relatively high pH value. Additionally, during charging and discharging, the Li₂CO₃ remaining on the surface of the ternary material decomposes, forming CO₂. Since the pressure of the CO₂ gas changes with temperature (especially when a reaction process involves a thermal reaction), swelling of the electrochemical energy storage device is exacerbated, thus degrading its storage performance.

[0016] By applying a coating layer to a surface of Lix Ni y Co z M k Me p O r A m The residual lithium content (such as LiOH or Li2CO3) on the surface of the positive active material can be reduced to a certain extent, thus achieving the goal of improving the storage performance of the electrochemical energy storage device. Furthermore, applying a coating layer to a Li surface can... x Ni y Co z M k Me p O r A m also the probability of side reactions due to direct contact between Li x Ni y Co z M k Me p O r A mand an electrolyte solution, thereby further reducing the amount of oxygen released from the positive active material to balance the charges during the charging and discharging process and thus reducing the risk of crystal structure collapse, with the Li2CO3 content on the surface of the positive active material being increased by applying a coating layer to the surface of Li x Ni y Co z M k Me p O r A m The amount of Li2CO3 obtained is lower than that of LiOH. Preferably, the content of Li2CO3 on the surface of the positive active material obtained by applying a coating layer to the surface of Li x Ni y Co z M k Me p O r A m The level obtained is less than 3000 ppm and the LiOH content is less than 5000 ppm.

[0017] The positive active material in the first aspect of this application consists of single-crystal or quasi-single-crystal particles, and the particle size D n 10 of the positive active material fulfills the following condition: 0.3 µm ≤ D n 10 ≤ 2 µm. Preferably, the particle size D meets n 10 of the positive active material the following condition: 0.5 µm ≤ D n 10 ≤ 1.5 µm.

[0018] The energy density, storage power, cycle power, and efficiency of the electrochemical energy storage device are closely related to the physical and chemical properties of the positive active material. The ternary material is a positive active material that mainly contains the transition metal elements Ni and Co, which are adjacent in the same period. It achieves charge equilibrium through changes in the valence states of Ni and Co, with Ni being one of the most important active metal components and primarily existing in the +2 valence state. During a lithiation / delithiation process, Ni 2+ to Ni 3+ and Ni 4+ oxidized. Co is also one of the active metal components and exists mainly in the +3 valence form. In a lithiation / delithiation process, Co 3+ to CO4 +oxidized. Therefore, in a lithiation / delithiation process, the ternary material achieves charge balance primarily through changes in the valence states of Ni and Co. As the proportions of Ni and Co change, the energy density, storage power, cycle power, and efficiency of the electrochemical energy storage device change to varying degrees.

[0019] In ternary materials, a higher Ni content generally indicates a greater capacity per gram and is more beneficial for increasing the energy density of the electrochemical energy storage device. However, if the Ni content in the ternary material is relatively high, the layered structure of the ternary material breaks down due to Ni mixing. 2+ and Li + together, whereby Li +It becomes more difficult to destack / stack from the ternary material, ultimately leading to a deterioration in the cycle performance of the electrochemical energy storage device. An increase in the Ni content of the ternary material further lowers its thermal decomposition temperature, resulting in greater heat dissipation and a deterioration of its thermal stability. As the Ni content of the ternary material increases, so does the Ni content. 4+with strong oxidation. When the electrolyte solution comes into contact with the ternary material, more side reactions occur between the electrolyte solution and the ternary material, and to maintain charge equilibrium, the ternary material releases oxygen. This not only destroys the crystal structure of the ternary material but also worsens the oxidation of the electrochemical energy storage device and degrades its storage performance.

[0020] The energy density, storage power, cycle power, and overall performance of the electrochemical energy storage device are further influenced by the density of the positive active material, which in turn is primarily determined by its morphology and structure. Currently, a commonly used ternary material typically consists of secondary particles formed by the agglomeration of primary particles; these are usually spherical and exhibit poor uniformity. A relatively large number of voids exist between the primary particles that form the secondary particles, resulting in a low density of the positive electrode plate and consequently affecting the energy density of the electrochemical energy storage device.Furthermore, the compressive strength of the secondary particles is relatively low, and some of the secondary particles can be crushed during the compaction process. Some of the crushed particles fall off the positive electrode plate because they are not in contact with a binder, and some of the crushed particles are not in contact with a conductivity agent, leading to a local degradation of the positive electrode plate's performance.

[0021] Taking into full consideration the effects of the aforementioned factors on the energy density, storage power, cycle power, and performance of the electrochemical energy storage device, the positive active material in the first aspect of this application is a ternary material in single-crystal or quasi-single-crystal particle morphology: Li x Ni y Co z M k Me p O r A m or Li xNi y Co z M k Along with p O r A mwith a coating on its surface. Since there are no cavities within the single-crystal or quasi-single-crystal particles, the particles are in close contact with each other and exhibit only small voids after the positive electrode plate has been fabricated. This contributes to increasing the compaction density of the positive electrode plate and improving the energy density of the electrochemical energy storage device. Because the single-crystal or quasi-single-crystal particles have an internal lattice with fewer defects and high structural stability, they can provide a three-dimensional channel for the migration and diffusion of lithium ions and accelerate the lithium ion migration rate during the charging and discharging processes of the electrochemical energy storage device, thus not affecting the cycle performance and efficiency of the electrochemical energy storage device.

[0022] In ternary materials with single-crystal or quasi-single-crystal particle morphology, the lithium and nickel content in small single-crystal or quasi-single-crystal particles is typically higher than average (i.e., excessive lithium and nickel), while the lithium and nickel content in large single-crystal or quasi-single-crystal particles is below average (i.e., insufficient lithium and nickel). During charging, excessive delithiation always occurs in small single-crystal or quasi-single-crystal particles due to polarization, leading to damage to their structure.Furthermore, a single-crystal or quasi-single-crystal particle with a small particle size has a larger specific surface area and exhibits more side reactions when in contact with the electrolyte solution compared to a single-crystal or quasi-single-crystal particle with a large particle size. To maintain charge balance, the small-sized single-crystal or quasi-single-crystal particle releases more oxygen, which not only disrupts the crystal structure of the small-sized single-crystal or quasi-single-crystal particle but also exacerbates swelling of the electrochemical energy storage device and degrades its storage performance.

[0023] Furthermore, in a positive active material with a broad particle size distribution, the volume fraction of small-particle powder, especially micropowder, within the positive active material is generally negligible. Therefore, expressing the micropowder content in the positive active material using a conventional volume particle size is inaccurate, and expressing it using a number particle size is more accurate and intuitive, which is helpful for properly controlling the source of the electrochemical energy storage device.

[0024] Furthermore, the positive active material in the first aspect of this application is a ternary material Li. x Ni y Co z M k Me p O r A m , or Li x Ni y Co z M k Me p O r A mwith a coating on its surface, with a particle size D n 10, the 0.3µm≤D n 10≤2µm is fulfilled, which can effectively reduce the probability of damage to the structure of the positive active material with single-crystal or quasi-single-crystal particle morphology and reduce gas production.

[0025] Therefore, in this application, the particle morphology of the positive active material and the amount of micropowder in the positive active material are appropriately controlled to effectively reduce side reactions between the positive active material and the electrolyte solution, decrease gas evolution from the electrochemical energy storage device, and improve the storage performance of the electrochemical energy storage device without compromising the energy density, cycle performance, and efficiency of the electrochemical energy storage device.

[0026] Preferably, in Lix Ni y Co z M k Me p O r A m , 0.50≤y≤0.90, 0.05≤z≤0.2, 0.05≤k≤0.4, and 0≤p≤0.05.

[0027] Preferably, in Li x Ni y Co z M k Me p O r A m , 0.70≤y≤0.90, 0.05≤z≤0.2, 0.05≤k≤0.2, and 0≤p≤0.05. For a ternary material with a higher nickel content (0.70≤y≤0.90), a relative amount of micropowder with a small particle size has a greater influence on the residual lithium content and the gas production of the positive active material. Therefore, Dn10 of the high-nickel ternary material should be controlled with a single-crystal or quasi-single-crystal particle morphology: Li x Ni y Co z M k Me p O r A m , or Li x Ni y Co z M k Me p O r A mwith a coating on its surface that is within 0.3µm to 2µm, represents an effective means of solving the problem of gas evolution.

[0028] In particular, Li x Ni y Co z M k Me p O r A m LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.5 Co 0.25 Mn 0.25 O2, LiNi 0.55 CO 0.15 Mn 0.3 O2, LiNi 0.55 Co 0.1 Mn 0.35 O2, LiNi 0.55 Co 0.05 Mn 0.4 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.75 Co 0.1 Mn 0.15 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.85 Co 0.05 Mn 0.1 O2, LiNi 0.88 Co 0.05 Mn 0.07 O2, or LiNi 0.9 Co 0.05 Mn 0.05O2, be, or may be a substance obtained by modification by partial replacement of the dopant Me and / or the dopant A by an element in the foregoing substance.

[0029] In the case of the positive active material according to the first aspect of this application, coating the surface of Li x Ni y Co z M e Me p O r A m a direct contact between Li x Ni y Co z M k Me p O r A mand the electrolyte solution are avoided, and side reactions between the positive active material and the electrolyte solution are reduced. Preferably, a coating element in the coating layer is selected from one or a combination of Al, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P. Even more preferably, a coating element in the coating layer is selected from a combination of two or more of Al, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P.

[0030] Preferably, the coating layer comprises an oxide of the aforementioned coating element. Even more preferably, the coating layer comprises oxides formed from two or more of the aforementioned coating elements. If the coating layer comprises oxides formed from at least two coating elements, the adhesion strength of the coating layer to the surface of Li can be increased. x Ni y Co z M k Me p O r Am to improve the coating layer so that it has a certain degree of ionic conductivity and electronic conductivity, thereby mitigating the influence of the coating layer on the polarization of the positive active material.

[0031] In the positive active material of the first aspect of this application, the particle size D n 10 of the positive active material, measured in µm, and a particle size D v 10 of the positive active material, measured in µm, the following condition: 0.15 ≤ D n 10 × D v 10 ≤ 6. Preferably, the particle size D n 10 of the positive active material, measured in µm, and the particle size D v 10 of the positive active material, measured in µm, the following condition: 0.45 ≤ D n 10 × D v 10 ≤ 6, where D v10 a corresponding particle size is reached when a cumulative volume distribution percentage of the positive active material reaches 10%, and D n 10. A corresponding particle size is reached when a cumulative number distribution percentage of the positive active material reaches 10%. If the product of D n 10 and D v If the percentage of the positive active material lies within the aforementioned range, this means that the relative amount of micropowder with an excessively small particle size in the positive active material is relatively low, and that the capacity of the positive active material is relatively high. This is helpful in mitigating the problem of gas formation in the positive active material while simultaneously ensuring that the volumetric energy density of the electrochemical energy storage device is relatively high.

[0032] Preferably the particle size D v10 of the positive active material 0.5 µm to 3 µm. Even more preferably the particle size D v 10 of the positive active material 1 µm to 2 µm.

[0033] In the positive active material according to the first aspect of this application, the theoretical specific surface area BET1 of the positive active material and the actual specific surface area BET2 of the positive active material satisfy the following condition: 0.3 ≤ (BET2 - BET1) / BET1 ≤ 5.5.

[0034] The theoretical specific surface area of ​​the positive active material BET1=6 / (ρ×D) v 50). ρ is the actual density of the positive active material, measured in g / cm³. D v 50 is the corresponding particle size when the cumulative volume distribution percentage of the positive active material reaches 50%, with the unit of measurement µm.

[0035] The actual specific surface area BET2 of the positive active material can be measured using the N2 adsorption method. For details, refer to GB / T19587-2004.

[0036] In this application, (BET2-BET1) / BET1 represents the degree of deviation between the theoretical and actual specific surface area of ​​the positive active material and can reflect the degree of surface roughness. By controlling the degree of deviation between the theoretical and actual specific surface area of ​​the positive active material within a certain range, it can be ensured that the surface of the formed positive active material is relatively flat and exhibits fewer irregularities, which can also indicate relatively good uniformity of the sizes of the single-crystal or quasi-single-crystal particles. This is helpful for reducing the polarization of the positive active material, improving ion transport performance, further reducing gas production, and optimizing dynamic performance.

[0037] Preferably, the actual specific surface area BET2 of the positive active material is 0.5 m². 2 / g up to 1.5 m 2 / g. If the actual specific surface area of ​​the positive active material lies within the aforementioned range, the contact area between the electrolyte solution and the positive active material is relatively small. This is helpful in inhibiting side reactions and preventing the source problem of the electrochemical energy storage device from being exacerbated by corrosion damage caused by the electrolyte solution to the crystal structure of the positive active material. Furthermore, if the actual specific surface area of ​​the positive active material lies within the aforementioned range, this is helpful in achieving relatively strong adhesion of the positive active material to the binder and the conductivity agent with fewer additives when preparing a positive slurry by mixing, thereby increasing the energy density of the electrochemical energy storage device.

[0038] Preferably the particle size D v 50 of the positive active material 1 µm to 6 µm. Even more preferably the particle size D v 50 of the positive active material 2 µm to 5 µm.

[0039] Preferably the particle size D v 90% of the positive active material is 3 µm to 12 µm. Even more preferably, the particle size is D. v 90 of the positive active material 3 µm to 10 µm.

[0040] In the positive active material according to the first aspect of this application, the differential volume-based particle size distribution curve of the positive active material preferably has a single peak. The differential particle size distribution curve comprises both a differential volume-based particle size distribution curve and a differential number-based particle size distribution curve.

[0041] Next, the process for producing a positive active material according to the second aspect of this application, which is used to produce the positive active material of the first aspect of this application, is described. The process comprises the following steps: introducing a ternary material precursor (a compound containing Ni, Co, and M), a Li-containing compound, a compound containing the dopant Me, and a compound containing the dopant A into a mixing device for mixing; subsequently introducing the mixture into an atmosphere furnace for sintering; and, after completion of sintering, performing staged sieving to obtain the positive active material.

[0042] The type of staged sieving is not specifically limited and can be selected according to the actual conditions. Preferably, the staged sieving can be staged air jet sieving or screen-supported sieving.

[0043] A specific process of graded air jet sieving is as follows: A sintered material is placed in an air jet classifier, and the sintered material is then ejected from a nozzle with an air stream of a specific pressure. Particles are separated according to size, utilizing the principle that particles of different sizes have different weights, with a lighter particle flying closer and a heavier particle flying farther. The distance between a collector and the nozzle is adjusted to sieve a suitable particle size to obtain the desired active material.

[0044] A specific sieve-assisted sieving process is as follows: A sintered material is placed in a sieve with a mesh size of 200 to 1000. Due to the varying particle sizes, smaller particles are filtered out by the sieve, while larger particles are retained to obtain the desired active material. Preferably, the sieve has a mesh size of 500 to 800.

[0045] The ternary material precursor can include, among other things, the following: Ni 1 / 3 Co 1 / 3 Mn 1 / 3 (OH)2, Ni 0.3 Co 0.2 Mn 0.3 (OH)2, Ni 0.5 Co 0.25 Mn 0.25 (OH)2, Ni 0.55 Co 0.15 Mn 0.3 (OH)2, Ni 0.55 Co 0.1 Mn 0.35 (OH)2, Ni 0.55 Co 0.05 Mn 0.4 (OH)2, Ni 0.6 Co 0.2 Mn 0.2 (OH)2, Ni 0.75Co 0.1 Mn 0.13 (OH)2, Ni 0.8 Co 0.1 Mn 0.1 (OH)2 Ni 0.88 Co 0.05 Mn 0.07 (OH)2, 0.9Ni 0.8 Co 0.2 (OH)2·0.1Al2(OH)3, and 0.9Ni 0.9 CO 0.05 Mn 0.03 (OH)2·0.1Al2(OH) 3.

[0046] The Li-containing compound may contain, among other things, one or a combination of the following: LiOH·H2O, LiOH, Li2CO3, and Li2O.

[0047] The compound containing the doping element Me can be an oxide, nitrate and / or carbonate containing at least one of the elements Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W and Nb.

[0048] The compound containing the doping element A may include, among others, one or a combination of LiF, NaCl, Na2S and Li3N.

[0049] Sintering conditions can range from 700 °C to 800 °C and an oxygen concentration of ≥ 20%.

[0050] Next, a further method for producing a positive active material according to the third aspect of this application, which is used to produce the positive active material in the first aspect of this application, is described. The method comprises the following steps: S1. A ternary material precursor (a compound containing Ni, Co, and M), a Li-containing compound, a compound containing the dopant Me, and a compound containing the dopant A are placed in a mixing device for mixing and then placed in an atmosphere furnace for primary sintering. S2. A material obtained after primary sintering and a compound containing the coating element are placed in the mixing device for mixing and then placed in the atmosphere furnace for secondary sintering. S3.A graded sieving process is carried out on the material obtained after secondary sintering in order to obtain the positive active material.

[0051] The type of staged sieving is not specifically limited and can be selected according to the actual conditions. Preferably, the staged sieving can be staged air jet sieving or screen-supported sieving.

[0052] A specific process of graded air jet sieving is as follows: The material obtained after secondary sintering is fed into an air jet classifier and then ejected from a nozzle at a specific pressure. The particles are separated by size, utilizing the principle that particles of different sizes have different weights: a lighter particle is lighter and travels closer, while a heavier particle is heavier and travels farther. The distance between a collector and the nozzle is adjusted to sieve a suitable particle size to obtain the desired active material.

[0053] A specific sieve-assisted sieving process is as follows: The material obtained after secondary sintering is placed in a sieve with a mesh size of 200 to 1000 meshes. Due to the varying particle sizes, smaller particles are filtered out by the sieve, while larger particles are retained to obtain the desired active material. Preferably, the mesh size of the sieve is 500 to 800 meshes.

[0054] The ternary material precursor can include, among other things, the following: Ni 1 / 3 Co 1 / 3 Mn 1 / 3 (OH)2, Ni 0.3 Co 0.2 Mn 0.3 (OH)2, Ni 0.5 Co 0.25 Mn 0.25 (OH)2, Ni 0.55 Co 0.15 Mn 0.3 (OH)2, Ni 0.55 Co 0.1 Mn 0.35 (OH)2, Ni 0.55 Co 0.05 Mn 0.4 (OH)2, Ni 0.6 Co 0.2 Mn 0.2 (OH)2, Ni0.75 Co 0.1 Mn 0.15 (OH)2, Ni 0.8 Co 0.1 Mn 0.1 (OH)2, Ni 0.88 Co 0.05 Mn 0.07 (OH)2, 0.9Ni 0.8 Co 0.2 (OH)2·0.1Al2(OH)3, and 0.9Ni 0.9 Co 0.05 Mn 0.05 (OH) 2· 0.1Al2(OH) 3.

[0055] The Li-containing compound may contain one or a combination of LiOH·H2O, LiOH, Li2CO3, and Li2O, but is not limited to these.

[0056] The compound containing the doping element Me can be an oxide, nitrate or carbonate, or a combination thereof, containing at least one of the elements Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W and Nb.

[0057] The compound containing the doping element A may include, among others, one or a combination of LiF, NaCl, Na2S and Li3N.

[0058] The compound containing the coating element can be one or a combination of an oxide, nitrate, phosphate, and carbonate containing one or more elements from Al, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P. The amount of the compound containing the coating element used can be 0.01% to 0.5% of the total mass of the positive active material.

[0059] The conditions for primary sintering can be 700 °C to 800 °C and an oxygen concentration of ≥ 20%.

[0060] One condition for secondary sintering can be 200 °C to 700 °C.

[0061] Next, the positive electrode plate according to the fourth aspect of this application is described. The positive electrode plate comprises a positive electrode current collector and a positive membrane, which is provided on at least one surface of the positive electrode current collector and comprises the positive active material according to the first aspect of this application.

[0062] In the positive electrode plate according to the fourth aspect of this application, the positive membrane can be arranged on one surface of the positive electrode current collector or on two surfaces of the positive electrode current collector.

[0063] In the positive electrode plate according to the fourth aspect of this application, the positive membrane may further contain a conductive agent and a binder, the types and contents of which are not specifically limited and may be selected according to the actual requirements. The binder typically comprises a fluorinated polyolefin binder. Water is typically a good solvent for the fluorinated polyolefin binder, i.e., the fluorinated polyolefin binder typically exhibits good solubility in water. For example, the fluorinated polyolefin binder may comprise, among others, polyvinylidene fluoride (PVDF), vinylidene fluoride copolymer, or a modified derivative thereof (e.g., modified with carboxylic acid, acrylic acid, or acrylonitrile), or the like.The conductive medium can be various conductive media suitable for an electrochemical energy storage device in engineering, including, but not limited to, one or a combination of acetylene carbon black, conductive carbon black, carbon fiber, carbon nanotubes and Ketjen carbon black.

[0064] In the positive electrode plate according to the fourth aspect of this application, the type of positive electrode current collector is also not further restricted and can be selected according to the actual requirements. The positive electrode current collector can generally be a layered body, and is typically a structure or component capable of collecting current. The positive electrode current collector can comprise various materials suitable for use as a positive electrode current collector in an electrochemical energy storage device in the technology. For example, the positive electrode current collector can comprise, but is not limited to, a metal foil, and in particular can comprise, but is not limited to, a nickel or aluminum foil.

[0065] Next, the electrochemical energy storage device according to the fifth aspect of this application is described. The electrochemical energy storage device comprises the positive active material according to the first aspect of this application.

[0066] With regard to the electrochemical energy storage device in the fifth aspect of this application, it should be noted that the electrochemical energy storage device can be a supercapacitor, a lithium-ion battery, a lithium-metal battery, or a sodium-ion battery. Only one embodiment is provided in this application, in which the electrochemical energy storage device is a lithium-ion battery, but this application is not limited to this.

[0067] The electrochemical energy storage device in the fifth aspect of this application may comprise a positive electrode plate, a negative electrode plate, a separator arranged between the positive electrode plate and the negative electrode plate, and an electrolyte solution, wherein the positive electrode plate is the positive electrode plate in the fourth aspect of this application and the positive electrode plate comprises the positive active material in the first aspect of this application.

[0068] A method for manufacturing the electrochemical energy storage device should be known to those skilled in the art. For example, the positive electrode plate, the separator, and the negative electrode plate can each be layered bodies that can thus be cut to a target size and then stacked one after the other, or wound to a target size to form an electrode array, and further combined with the electrolyte solution to form the electrochemical energy storage device.

[0069] In an electrochemical energy storage device, the negative electrode plate typically comprises a negative electrode current collector and a negative active material layer located on a surface of the negative electrode current collector. The negative active material layer typically comprises a negative active material. The negative active material can be various materials suitable for use in an electrochemical energy storage device in engineering, including, but not limited to, one or a combination of graphite, soft carbon, hard carbon, carbon fiber, a mesophased carbon microsphere, a silicon-based material, a tin-based material, lithium titanate, and another metal that can form an alloy with lithium.The graphite can be selected from one or a combination of synthetic graphite, natural graphite, and modified graphite. The silicon-based material can be selected from one or a combination of elemental silicon, a silicon-oxygen compound, a silicon-carbon composite, and a silicon alloy. The tin-based material can be selected from one or a combination of elemental tin, a tin-oxygen compound, and a tin alloy. The negative electrode current collector is typically a structure or component that collects current. The negative electrode current collector can comprise various materials suitable for use as a negative electrode current collector in an electrochemical energy storage device in engineering.For example, the negative electrode current collector can comprise a metal foil, in particular a copper foil, but is not limited to this.

[0070] In the electrochemical energy storage device, the negative electrode plate can alternatively be a lithium plate.

[0071] In the electrochemical energy storage device, the separator can comprise various materials suitable for use as a separator in an electrochemical energy storage device in engineering, including, but not limited to, one or a combination of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester and natural fiber.

[0072] In the electrochemical energy storage device, the electrolyte solution can be various electrolyte solutions suitable for a prior art electrochemical energy storage device. For example, the electrolyte solution typically comprises an electrolyte and a solvent, and the electrolyte can typically include a lithium salt. More specifically, the lithium salt can be an inorganic lithium salt and / or an organic lithium salt and can, in particular, but not limited to, include one or a combination of LiPF6, LiBF4, LiN(SO2F)2 (LiFSI), LiN(CF3SO2)2 (LiTFSI), LiClO4, LiAsF6, LiB(C2O4)2 (LiBOB), and LiBF2C2O4 (LiDFOB). Another example: The concentration of the electrolyte can be from 0.8 mol / l to 1.5 mol / l. The solvent can be various solvents suitable for an electrolyte solution in a prior art electrochemical energy storage device.The solvent of the electrolyte solution is generally a non-aqueous solvent, preferably an organic solvent, and may in particular comprise, but is not limited to, one or a combination of ethylene carbonate, propylene carbonate, 2,3-butylene carbonate, prenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate and a halogenated derivative thereof.

[0073] In some embodiments, the electrochemical energy storage device may include an outer packaging for encapsulating the positive electrode plate, the negative electrode plate, and the electrolyte. In one example, the positive electrode plate, the negative electrode plate, and the separator may be stacked or wound to form a stacked or wound electrode assembly, and the electrode assembly is encapsulated in the outer packaging. An electrolyte solution may be used, and the electrode assembly is immersed in the electrolyte solution. The electrochemical energy storage device may have one or more electrode assemblies, and the number of electrode assemblies can be adjusted as required.

[0074] In some embodiments, the outer packaging of the electrochemical energy storage device can be a soft package, for example, a soft bag. The material of the soft package can be plastic, for example, one or more of the following materials: polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS). Alternatively, the outer packaging of the electrochemical energy storage device can be a hard shell, for example, an aluminum shell.

[0075] This application is not subject to any particular restrictions regarding the shape of the electrochemical energy storage device, and the electrochemical energy storage device may be cylindrical, square, or any other shape. Fig. Figure 5 shows an electrochemical energy storage device with a square structure as an example.

[0076] In some embodiments, the electrochemical energy storage device can be assembled into a battery module, and the battery module can comprise a variety of electrochemical energy storage devices. A specific number can be tailored based on the application and capacity of the battery module.

[0077] Fig. Figure 6 shows a battery module 4 as an example. With reference to Fig. 6. Several electrochemical energy storage devices 5 can be arranged in series along a longitudinal direction of the battery module 4 or arranged in any other way within the battery module 4. Furthermore, the several electrochemical energy storage devices 5 can be fastened using a fastening element.

[0078] Optionally, the battery module 4 can also include a housing with a receiving space, and the multiple electrochemical energy storage devices 5 are housed in the receiving space.

[0079] In some embodiments, the foregoing battery module can be further assembled into a battery pack, and the number of battery modules contained in the battery pack can be adapted based on the application and capacity of the battery pack.

[0080] Fig. 7 and Fig. Figure 8 shows an example of a battery pack 1. With reference to Fig. 7 and Fig. 8. The battery pack 1 can comprise a battery housing and a plurality of battery modules 4 arranged within the battery housing. The battery housing comprises an upper housing body 2 and a lower housing body 3. The upper housing body 2 can cover the lower housing body 3, forming an enclosed space for the battery modules 4. The multiple battery modules 4 can be arranged in any configuration within the battery housing.

[0081] Finally, the device is described according to the sixth aspect of this application, wherein the device comprises the electrochemical energy storage device according to the fifth aspect of this application, and the electrochemical energy storage device can serve as a power supply for the device or as an energy storage unit for the device. The device includes, among other things, an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, or an electric truck), an electric train, a ship, a satellite, and the like. Furthermore, the electric train, the ship, and the satellite are all equipped with tools and, in a broader sense, are vehicles.

[0082] Depending on the requirements for the use of the device, an electrochemical energy storage device, a battery module or a battery pack can be selected for the device.

[0083] Fig. Figure 9 shows an example device. The device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or similar. To meet the device's requirements for high performance and high energy density as an electrochemical energy storage device, a battery pack or battery module can be used.

[0084] The following section describes this application in more detail using examples. It should be understood that these examples serve only to illustrate this application and do not limit its scope.

[0085] The lithium-ion batteries in Examples 1 to 8 and Comparative Examples 1 and 2 were manufactured according to the following procedure. (1) Production of a positive active material

[0086] The ternary material precursors Ni 0,8 Co 0,1 Mn 0,1 (OH)2, LiOH·H2O, and ZrO2 in a molar ratio of 0.997:1.05:0.003 were mixed in a mixer and then transferred to an oxygen-filled atmosphere furnace for sintering. After sintering, staged sieving was performed to select a suitable particle size for obtaining a positively active material, Li(Ni). 0,8 Co 0,1 Mn 0,1 ) 0,997 Zr 0,003 to obtain O2. (2) Production of a positive electrode plate

[0087] The positive active material, a polyvinylidene fluoride binder, and a carbon black conductive agent were mixed in a mass ratio of 98:1:1. N-methylpyrrolidone was then added, and the mixture was stirred uniformly using a vacuum mixer to obtain a positive slurry. The positive slurry was applied uniformly to a 12 µm thick aluminum foil, forming a positive electrode current collector. The aluminum foil was dried at room temperature and then placed in an oven at 100–130 °C for further drying. Finally, cold pressing and cutting were performed to obtain a positive electrode plate. (3) Production of a negative electrode plate

[0088] A negative active material consisting of graphite, a thickening agent of sodium carboxymethylcellulose, a binder of styrene-butadiene rubber, and a conductive agent of carbon black were mixed in a mass ratio of 97:1:1:1. Deionized water was added, and the mixture was stirred using a vacuum mixer to obtain a negative electrode suspension. The negative electrode suspension was applied uniformly to an 8 µm thick copper foil. The copper foil was dried at room temperature and then placed in an oven at 100 °C to 130 °C for further drying. Cold pressing and cutting were then performed to obtain a negative electrode plate. (4) Preparation of an electrolyte solution

[0089] An organic solvent was a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), with a volume ratio of EC, EMC, and DEC of 20:20:60. In a glovebox with an argon atmosphere and a water content of less than 10 ppm, fully dried lithium salt LiPF6 was dissolved in the organic solvent to obtain a uniformly mixed electrolyte solution, with a lithium salt concentration of 1 mol / L. (5) Production of a separator. A 12 µm thick polypropylene membrane was used as a separator. (6) Production of a lithium-ion battery.

[0090] The positive electrode plate, separator, and negative electrode plate were stacked sequentially, with the separator sandwiched between the positive and negative plates for insulation. After being wound into a square electrode assembly, the assembly was wrapped with an aluminum-plastic foil and baked at 80°C to remove water. The electrolyte solution was injected, and sealing was performed. Subsequently, standing, hot-cold pressing, chemical conversion, clamping, aging, and other processes were carried out to obtain a lithium-ion battery.

[0091] A lithium-ion battery in Example 9 was manufactured according to the following procedure. (1) Production of a positive active material

[0092] The ternary material precursors Ni 0,8 Co 0,1 Mn 0,1(OH)₂, LiOH·H₂O, and ZrO₂ in a molar ratio of 0.997:1.05:0.003 were placed in a mixer for mixing and then transferred to an oxygen-filled atmosphere furnace for primary sintering. The material obtained after primary sintering and 0.5 wt% Al₂O₃ were placed in a mixing device for mixing and then transferred to the atmosphere furnace for secondary sintering. Subsequently, the material obtained after secondary sintering underwent staged sieving to select a suitable particle size, resulting in a positive active material Li(Ni). 0,8 Co 0,1 Mn 0,1 ) 0,997 Zr 0,003 O2 was obtained with Al2O3 on its surface. (2) Production of a positive electrode plate

[0093] The positive active material, a polyvinylidene fluoride binder, and a carbon black conductive agent were mixed in a mass ratio of 98:1:1. N-methylpyrrolidone was then added, and the mixture was stirred uniformly using a vacuum mixer to obtain a positive slurry. The positive slurry was applied uniformly to a 12 µm thick aluminum foil, forming a positive electrode current collector. The aluminum foil was dried at room temperature and then placed in an oven at 100–130 °C for further drying. Finally, cold pressing and cutting were performed to obtain a positive electrode plate. (3) Production of a negative electrode plate

[0094] A negative active material consisting of graphite, a thickening agent of sodium carboxymethylcellulose, a binder of styrene-butadiene rubber, and a conductive agent of carbon black were mixed in a mass ratio of 97:1:1:1. Deionized water was added, and the mixture was stirred using a vacuum mixer to obtain a negative electrode suspension. The negative electrode suspension was applied uniformly to an 8 µm thick copper foil. The copper foil was dried at room temperature and then placed in an oven at 100 °C to 130 °C for further drying. Cold pressing and cutting were then performed to obtain a negative electrode plate. (4) Preparation of an electrolyte solution

[0095] An organic solvent was a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), with a volume ratio of EC, EMC, and DEC of 20:20:60. In a glovebox with an argon atmosphere and a water content of less than 10 ppm, fully dried lithium salt LiPF6 was dissolved in the organic solvent to obtain a uniformly mixed electrolyte solution, with a lithium salt concentration of 1 mol / L. (5) Production of a separator. A 12 µm thick polypropylene membrane was used as a separator. (6) Production of a lithium-ion battery.

[0096] The positive electrode plate, separator, and negative electrode plate were stacked sequentially, with the separator sandwiched between the positive and negative plates for insulation. After being wound into a square electrode assembly, the assembly was wrapped with an aluminum-plastic foil and baked at 80°C to remove water. The electrolyte solution was injected, and sealing was performed. Subsequently, standing, hot-cold pressing, chemical conversion, clamping, aging, and other processes were carried out to obtain a lithium-ion battery.

[0097] A lithium-ion battery according to Example 10 was produced using a process similar to the process for producing the lithium-ion battery according to Example 9, the difference being that in Example 10, 0.5 wt% Al2O3 was replaced by 0.5 wt% B2O3.

[0098] Next, a test procedure for the lithium-ion battery will be described. (1) Testing the residual lithium content on a surface of the positive active material

[0099] 30 g of powder from the prepared positive active material were taken and added to 100 ml of water, stirred for 30 minutes. The lithium remaining in the sample to be tested was titrated with a standard hydrochloric acid solution. A compound pH electrode was used as the indicator electrode, and the titration endpoint was determined by a sudden jump due to a change in potential. (2) High-temperature cycle performance test of the lithium-ion battery

[0100] At 45 °C, the lithium-ion battery was charged to 4.2 V with a constant current of 1 C, then to 4.2 V with a constant current of 0.05 C, and finally discharged to 2.8 V with a constant current of 1 C. The discharge capacity of the first cycle was recorded. The charging and discharging process was then repeated. When 80% of the initial capacity was reached after these repetitions, the charging and discharging was stopped. In this case, the number of cycles represented the high-temperature cycle life. (3) High-temperature storage performance test of the lithium-ion battery

[0101] At 25 °C, the lithium-ion battery was first charged to 4.2 V with a constant current of 1 C. Then, it was charged to 0.05 C with a constant voltage of 4.2 V. The volume of the lithium-ion battery was measured using a discharge method and recorded as the initial volume. The battery was then stored at 80 °C for 10 days. After storage, the volume was measured again using the discharge method and recorded as the volume of the lithium-ion battery after 10 days at 80 °C. Volume expansion rate (%) of the lithium-ion battery stored for 10 days at 80°C = [Volume of the lithium-ion battery stored for 10 days at 80°C / Initial volume of the lithium-ion battery - 1] × 100%. (4) Capacity test of the positive active material of the lithium-ion battery

[0102] The lithium-ion battery was stored for 2 hours at a constant temperature of 25 °C, then charged from 2.8 V to 4.2 V at 1 / 3 C, subsequently charged at a constant voltage of 4.2 V with a current of less than or equal to 0.05 mA, then stored for 5 minutes, and finally discharged at 1 C to 2.8 V. The capacity of the lithium-ion battery was recorded, and the measured capacity was divided by the mass of the positive active material in the battery to obtain the capacity of the positive active material in the lithium-ion battery. Table 1 Parameters of the positive active materials in examples 1 to 10 and comparison examples 1 and 2 D n 10(µm) D v 10(µm) D v 50(µm) BET2(m 2 / g) (BET2-BET1) / BET1 Coating material Example 1 0.30 0.50 3.3 1.00 1.59 \ Example 2 0.60 0.90 4.0 0.80 1.51 \ Example 3 0.90 1.50 4.3 0.90 2.03 \ Example 4 1.30 2.10 5.1 1.10 3.39 \ Example 5 1.80 2.30 5.5 0.80 2.45 \ Example 6 2.00 3.00 6.0 0.70 2.29 \ Example 7 0.60 1.40 5.3 1.50 5.23 \ Example 8 0.80 1.30 2.5 0.70 0.37 \ Example 9 1.00 1.40 3.3 0.70 0.81 Al2O3 Example 10 0.80 1.50 2.5 0.80 0.57 B2O3 Comparison example 1 0.10 1.10 4.0 0.50 0.57 \ Comparison example 2 2.50 3.20 4.0 0.50 0.57 \ Table 2 Performance test results of examples 1 to 10 and comparison examples 1 and 2 Li2CO3 (ppm) LiOH(ppm) Positive active material capacity (mAh / g) Number of cycles at 45°C Rate of volume expansion after storage at 80°C for 10 days Example 1 2354 3451 196 1231 104% Li2CO3 (ppm) LiOH(ppm) Positive active material capacity (mAh / g) Number of cycles at 45°C Rate of volume expansion after storage at 80°C for 10 days Example 2 2234 3612 197 1104 99% Example 3 2131 3588 195 1154 95% Example 4 2554 3821 194 1097 93% Example 5 2764 3353 193 1066 92% Example 6 2481 3221 192 1012 90% Example 7 2941 4312 196 1078 111% Example 8 2651 4231 195 1208 106% Example 9 2052 3125 195 1265 94% Example 10 2024 3021 196 1198 92% Comparison example 1 3042 4675 196 998 142% Comparison example 2 2231 3541 190 1005 105%

[0103] The analysis of the test results in Table 2 shows that in the positive active materials of the lithium-ion batteries in examples 1 to 10, the relative proportion of micropowder with a particle size of less than 1 µm in the positive active material was lower, and the positive active material exhibited a higher capacity. Furthermore, the lithium-ion battery showed a longer lifetime at high temperatures and a lower volume swelling rate during storage at high temperatures.Therefore, appropriate control of the particle morphology of the positive active material and the amount of micropowder in the positive active material could effectively reduce side reactions between the positive active material and the electrolyte solution, decrease gas evolution from the lithium-ion battery, and improve the storage performance of the lithium-ion battery without affecting the energy density, cycle performance, and overall performance of the lithium-ion battery.

[0104] In comparative example 1, D n 10 of the positive active material is further reduced to 0.1 µm. From the differential volume-based particle size distribution curve and the differential number-based particle size distribution curve in Fig. 1 and Fig.Figure 2 shows that the particle size distribution curves of the positive active material both exhibited two peaks. One possible reason for this was that the relative proportion of micropowder in the positive active material was too high. From Fig. 3 and Fig.Figure 4 shows that the differential volume-based particle size distribution curve and the differential number-based particle size distribution curve of the positive active material in this application were both unimodal, further indicating that the relative proportion of micropowder in the positive active material was relatively low. When the relative proportion of micropowder in the positive active material was too high, more side reactions occurred when the positive active material came into contact with the electrolyte solution, because the specific surface area of ​​the micropowder was larger, the amount of residual lithium on the surface was higher, and the contact area with the electrolyte solution was larger.To maintain charge balance, the positive active material with micropowder released more oxygen, which not only destroyed the crystal structure of the positive active material but also worsened the swelling of the lithium-ion battery and degraded the storage performance of the lithium-ion battery.

[0105] In comparative example 2, D was n 10 of the positive active material 2.5 µm. In this case, the micropowder content in the positive active material was relatively low, but due to the peculiarity of the single-crystal or quasi-single-crystal morphology, D vThe particle size distribution of the positive active material had to be kept within a specific range to maintain high ion transport performance and low polarization strength. Therefore, the particle size distribution of the positive active material was too narrow; consequently, it was not possible to match the particle sizes of the positive active material to small and large particles, and it was difficult to achieve a high compaction density. The particles of the positive active material were more prone to breakage during the cold pressing and battery cycle of the electrode plate, resulting in direct contact between a large amount of fresh surface area and the electrolyte solution, thus increasing the swelling of the lithium-ion battery.

[0106] Further analysis of the test results from Examples 1 to 8 also revealed that controlling the degree of deviation between a theoretical specific surface area BET1 and an actual specific surface area BET2 of the positive active material allowed for further optimization of the positive active material's microstructure. This ensured that the surface of the single-crystal or quasi-single-crystal positive active material exhibited fewer irregularities. This contributed to reducing the polarization of the positive active material, improving the ion transport properties, further reducing gas evolution from the lithium-ion battery, and optimizing the lithium-ion battery's dynamic properties.

[0107] In comparison to Example 1, Examples 9 and 10 yielded a positive active material obtained by coating the surface of the positive active material in Example 1. After coating, direct contact between Li(Ni) 0,8 Co 0,1 Mn 0,1 ) 0,997 Zr 0,003 Exposure to O2 and the electrolyte solution was avoided, and the probability of side reactions between the positive active material and the electrolyte solution was reduced. Furthermore, a coating layer with Al2O3 and B2O3 exhibited good ionic and electronic conductivity, thereby mitigating the problem of gas formation and simultaneously minimizing the influence of the coating layer on the polarization of the positive active material.

Claims

[1] Electrochemical energy storage device, wherein the electrochemical energy storage device comprises positive active material and negative active material, wherein the positive active material is a ternary material comprising Ni, Co and M, wherein the ratio of nickel, cobalt and manganese is y:z:k, y+z+k=1, 0.7 ≤ y ≤ 0.9, and M is selected from one or two of the elements Mn and Al. where the particle size D n 10 of the positive active material 0.3 µm ≤ D n 10 ≤ 2 µm is fulfilled, where the particle size D v 10 of the positive active material 0.5 µm ≤ D v 10 ≤ 3 µm fulfilled; where D n 10 a corresponding particle size is when a cumulative number distribution percentage of the positive active substance reaches 10%, where D v 10 a corresponding particle size is when a cumulative volume distribution percentage of the positive active substance reaches 10%. [2] Electrochemical energy storage device according to claim 1, wherein the particle size D n 10 of the positive active material 0.5 µm ≤ D n 10 ≤ 1.5 µm is met. [3] Electrochemical energy storage device according to claim 1, wherein the particle size D v 10 of the positive active material 1 µm ≤ D v 10 ≤ 2 µm is fulfilled. [4] Electrochemical energy storage device according to claim 1, wherein the positive active material consists of single-crystal or quasi-single-crystal particles. [5] Electrochemical energy storage device according to claim 1, wherein the surface of the positive active material comprises a coating layer, the coating layer comprising one or more coating elements. [6] Electrochemical energy storage device according to claim 5, wherein one or more coating elements are selected from Al, Ba, Zn, Ti, Co, W, Y, Si, Sn, B and P. [7] Electrochemical energy storage device according to claim 5, wherein the coating layer comprises at least two coating elements. [8] Electrochemical energy storage device according to claim 5, wherein the content of Li2CO3 on the surface of the positive active material is lower than that of LiOH. [9] Electrochemical energy storage device according to claim 8, wherein the Li2CO3 content is less than 3000 ppm and the LiOH content is less than 5000 ppm. [10] Electrochemical energy storage device according to claim 1, wherein the particle size D v 50 of the positive active material is 1 µm to 6 µm. [11] Electrochemical energy storage device according to claim 1, wherein the particle size D v 50 of the positive active material is 2 µm to 5 µm. [12] Electrochemical energy storage device according to claim 1, wherein the particle size D n10 of the positive active material, measured in µm, and a particle size Dv10 of the positive active material, measured in µm, meet the following condition: 0.15 ≤ D n 10 × D v 10 ≤ 6. [13] Electrochemical energy storage device according to claim 1, wherein a theoretical specific surface area BET1 of the positive active material and an actual specific surface area BET2 of the positive active material satisfy the following condition: 0.3 ≤ (BET2-BET1) / BET1 ≤ 5.5, BET1 = 6 / (ρ × D v 50), where ρ is an actual density of the positive active material and a unit of measurement is g / cm3 and D v 50 is a corresponding particle size when the cumulative volume distribution percentage of the positive active material reaches 50%, and the unit of measurement is µm. [14] Electrochemical energy storage device according to claim 1, wherein the negative active material comprises a silicon-oxygen compound and a silicon-carbon composite. [15] Electrochemical energy storage device according to claim 1, wherein the electrochemical energy storage device also comprises an electrolyte solution, wherein the electrolyte solution comprises electrolyte and solvent, wherein the concentration of the electrolyte is 0.8 mol / l to 1.5 mol / l and the electrolyte comprises one or a combination of LiPF6 and LiN(SO2F)2 (hereinafter referred to as LiFSI). [16] Electrochemical energy storage device according to claim 1, wherein the actual specific surface area BET2 of the positive active material is 0.5 m² 2 / g up to 1.5 m 2 / g.

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