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

Abstract

A positive active material, whereby the positive active 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 m is, whose surface is provided with a top layer, where 0.85≤x≤1.15, 0 <y<1, 0<z<1, 0<k<1, 0≤p≤0, 1≤r≤2, 0≤m≤1, m+r≤2, M ausgewählt ist aus einem oder zwei von Mn und Al, Me mindestens ein Element von Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W und Nb enthält und A einschließt, aber nicht beschränkt ist auf eines oder eine Kombination von mehreren von N, F, S und Cl; und The positive active material consists of secondary particles, and the particle size D n 10 of the positive active material meets the conditions: 0.5 µm≤D n 10≤3 µm.

Description

TECHNICAL AREA

[0001] This utility model relates to the field of electrochemical technologies and in particular to 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 crises and environmental problems, the development of new green energy sources has become urgently necessary. Lithium-ion batteries are used in many areas due to their advantages, such as high specific energy, operation across a wide temperature range, low self-discharge, long lifespan, good safety, and environmental friendliness. Furthermore, there is a gradual global effort to replace conventional diesel vehicles with new energy vehicles powered by lithium-ion batteries. However, the currently used positive active materials, such as lithium iron phosphate (LiFePO4) and low-nickel ternary materials (LiNi), are not yet fully developed. 1 / 3 Co 1 / 3 Mn 1 / 3O2) do not fully meet the energy density requirements of lithium-ion batteries due to inherent material limitations. The energy density of lithium-ion batteries can be improved by increasing the nickel content in the ternary material. Therefore, high-nickel ternary materials are currently one of the main research areas for positive active materials for lithium-ion batteries. However, with increasing nickel content, the side reactions between the ternary material and the electrolyte 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 gassing problem of lithium-ion batteries at the material level mainly include 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, all these methods affect the performance of lithium-ion batteries to varying degrees, e.g., by reducing the reversible capacity per gram of the lithium-ion batteries and by deteriorating cycle stability.

[0004] Therefore, effective technical methods are needed to increase the energy density of lithium-ion batteries to meet increasingly stringent application requirements, while simultaneously reducing the gas production of lithium-ion batteries and improving the storage performance of lithium-ion batteries. SUMMARY OF THE INVENTION

[0005] In light of the existing problems, one objective of this utility model 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, decrease gas production from the electrochemical energy storage device, and improve the storage performance of the electrochemical energy storage device without compromising its energy density, cycle stability, and rate performance.

[0006] To achieve the aforementioned goal, one aspect of this application provides for a 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 Me p O r Am , whose surface is provided with a top layer, 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 ausgewählt ist und Nb ausgewählt ist und A aus einem oder mehreren der Elemente N, F, S und Cl ausgewählt ist. Bei dem positiven aktiven Material handelt es sich um Sekundärpartikeln, und die Partikelgröße D n 10 of the positive active material meets the conditions: 0.5 µm≤D n 10≤3 µm.

[0007] According to another aspect of this application, this application provides a positive electrode plate, wherein the positive electrode plate contains the positive active material in that 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 contains the positive active material from the other aspect of this application.

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

[0010] This application has, among other things, the following positive effects:

[0011] In this application, the particle morphology of the positive active material and the amount of micropowder within the positive active material are precisely controlled to effectively reduce side reactions between the positive active material and an electrolyte, decrease gas production from the electrochemical energy storage device, and improve the storage performance of the electrochemical energy storage device without compromising its energy density, cycle stability, or rate performance. The device in this application incorporates the electrochemical energy storage device and therefore offers at least the same advantages as a standard electrochemical energy storage device. BRIEF DESCRIPTION OF THE DRAWINGS Fig. is a differential volume-based particle size distribution curve of a positive active material from comparison example 1 of this application; Fig.is a differential number-based particle size distribution curve of a positive active material from comparison example 1 of this application; Fig. is a differential volume-based particle size distribution curve of a positive active material in Example 3 of this application; Fig. is a differential number-based particle size distribution curve of a positive active material in Example 3 of this application; Fig. is a perspective view of an embodiment of an electrochemical energy storage device; Fig. is a perspective view of an embodiment of a battery module; Fig. is a perspective view of an embodiment of a battery pack; Fig. is an exploded view of Fig. ; and Fig.is a schematic diagram of an embodiment of a device that uses an electrochemical energy storage device as a power supply. Description of the signs: 1 set of batteries 2 upper housing body 3 lower housing body 4 battery modules 5 electrochemical energy storage DESCRIPTION OF THE EXECUTION FORMS

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

[0013] First, the positive active material is described according to the first aspect of the present 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 Lix Ni y Co z M k Me p O r A m , whose surface is provided with a top layer, 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 asugewählt ist und Nb, und A aus einem oder mehreren der Elemente N, F, S und Cl ausgewählt ist.

[0015] In the actual manufacturing process of a ternary material, melting, decomposition, and volatilization losses can occur due to potential impurities and the low melting point of the lithium salt raw material at relatively low temperatures. Therefore, an excess of lithium salt is added during the ternary material's production to compensate for lithium loss during the sintering process. The surface of the ternary material exhibits reactive oxygen anions that react with CO₂ and H₂O in the air to form carbonate. Meanwhile, lithium ions migrate from an initial location to the surface, forming Li₂CO₃ on the surface of the ternary material. This process is accompanied by a reduction (deoxidation) of the ternary material's surface, resulting in the formation of a distorted oxide layer.Furthermore, the addition of excess lithium salt during the synthesis of the ternary material results in the main products of the excess lithium salt, calcined at high temperature, being Li oxides. These Li oxides react with CO₂ and H₂O in air to form LiOH and Li₂CO₃, which remain on the surface of the ternary material, leading to a relatively high pH value. Moreover, the Li₂CO₃ remaining on the surface of the ternary material decomposes during charging and discharging, producing CO₂. Since the CO₂ gas creates a pressure differential due to temperature differences (especially when a reaction process is accompanied by a thermal reaction), it exacerbates the swelling of the electrochemical energy storage device and degrades its storage performance.

[0016] The provision of a top layer on a surface of Lix Ni y Co z M k Me p O r A m This can reduce the residual lithium content (such as LiOH or Li2CO3) on the surface of the positive active material to a certain extent and achieve the goal of improving the storage performance of the electrochemical energy storage device. Furthermore, providing a cover layer on a Li surface can x Ni y Co z M k Me p O r A m also reduce the probability of side reactions caused by direct contact between Li x Ni y Co z M k Me p O r A mand an electrolyte, which further reduces the amount of oxygen released by the positive active material to balance charges during charging and discharging, thus reducing the risk of a resulting collapse of the crystal structure. The Li₂CO₃ content on the surface of the positive active material, achieved by applying a cover layer to the surface of Li x Ni y Co z M k Me p O r A m The Li₂CO₃ content obtained is lower than that of LiOH. Preferably, the Li₂CO₃ content on the surface of the positive active material, which is obtained by applying a cover layer to the surface of Li₂CO₃, is lower than that of Li₂CO₃. x Ni y Co z M k Me p O r A m The LiOH content is less than 3000 ppm and less than 5000 ppm.

[0017] The positive active material in the first aspect of this application has the morphology of secondary particles, and the particle size D n 10 of the positive active material is fulfilled: 0.5 µm≤D n 10≤3 µm. Preferably the particle size D n 10 of the positive active material the following conditions: 1 µm≤D n 10≤2 µm.

[0018] The energy density, storage power, cycle stability, and rate power 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 positively active material that primarily contains the transition metal elements nickel (Ni) and cobalt (Co), which are adjacent in the same period and achieve charge balance through changes in the valence states of Ni and Co. Ni is one of the most important active metal elements and exists mainly in the +2 valence state. During the deintercalation of lithium, Ni 2+ to Ni 3+ and Ni 4+ Co is oxidized. Co is also one of the active metallic elements, primarily in the form of the +3 oxidation state. Co is produced during the deintercalation of lithium. 3+ to Co 4+oxidized. Therefore, during lithium deintercalation, 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 stability, and rate power of the electrochemical energy storage device change to varying degrees.

[0019] A higher nickel content in the ternary material generally means a greater capacity per gram of the ternary material and is more helpful in increasing the energy density of the electrochemical energy storage device. However, if the nickel content in the ternary material is relatively high, the layered structure of the ternary material breaks down due to nickel mixing. 2+ and Li + together, which is the deintercalation of Li +in the ternary material, this is made more difficult and ultimately leads to a deterioration of the cycle stability of the electrochemical energy storage device. An increase in the Ni content in the ternary material further lowers the thermal decomposition temperature of the ternary material, leading to an increase in heat release and a deterioration of the thermal stability of the ternary material. As the Ni content in the ternary material increases, the amount of Ni also increases. 4+ with strong oxidizability. When the electrolyte comes into contact with the ternary material, further side reactions occur between the electrolyte and the ternary material, and to maintain charge balance, the ternary material releases oxygen. This not only destroys the crystal structure of the ternary material but also exacerbates the swelling of the electrochemical energy storage device and degrades its storage performance.

[0020] Compared to a positive active material with a large particle size, a positive active material with a small particle size has a larger specific surface area, a larger contact area between the small-particle-sized positive active material and the electrolyte, and more side reactions can occur when the positive active material is in contact with the electrolyte. To maintain charge balance, the small-particle-sized positive active material may release more oxygen, which can not only disrupt the crystal structure of the ternary material but also exacerbate swelling of the electrochemical energy storage device and degrade its storage performance.Meanwhile, the positively active material with its small particle size has weak compressive strength and is more prone to fragmentation, producing more primary particles during the cold pressing of an electrode plate. Some of these primary particles can detach from the positive current collector because they are not in contact with a binder, and some can locally degrade the performance of the positive electrode plate because they are not in contact with a conductive medium.

[0021] Furthermore, in general, for a positive active material with a broad particle size distribution, the volume percentage of powder with a small particle size, especially micropowder, in the positive active material is negligible. Therefore, a conventional volume particle size used to express the amount of micropowder in the positive active material is relatively crude, while a numerical particle size used to express the amount of micropowder in the positive active material is more accurate and intuitive, which is helpful for properly controlling the swelling of the electrochemical energy storage device.

[0022] Taking into full consideration the effects of the aforementioned factors on the energy density, storage power, cycle stability and rate power of the electrochemical energy storage device, the positive active material described in the first aspect of this application is a ternary material in the form of secondary particles: LixNiyCozMkMepOrAm or LixNiyCozMkMepOrAm, the surface of which is provided with a cover layer, wherein the particle size Dn10 meets the condition 0.5 µm≤D nThe particle morphology of the positive active material and the amount of micropowder in the positive active material are precisely controlled to effectively reduce side reactions between the positive active material and the electrolyte, decrease gas production from the electrochemical energy storage device, and improve the storage performance of the electrochemical energy storage device without compromising energy density, cycle stability, and rate performance.

[0023] Preferably in Li x 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.

[0024] Preferably, Li x Ni y Co z M k Me p O r A m0.70 ≤ 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), the relative amount of micropowder with a small particle size has a greater influence on the residual lithium content and the gassing problem of the positively active material. Therefore, the control of D n 10 of the high-nickel ternary material with secondary 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 m , whose surface is covered with a coating, to a value between 0.5 µm and 3 µm, an effective means of solving the gassing problem.

[0025] In particular, Li x Ni y Co z M k Me p O r A m for example LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0,5 Co0,2 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 0,8 Mn 0,1 O2, LiNi 0,85 Co 0,05 Mn 0,5 O2, LiNi 0,88 Co 0,05 Mn 0,07 O2, or LiNi 0,9 Co 0,05 Mn 0,05 O2, or can be a substance obtained by modification through partial replacement of the aforementioned substance by the doping element Me and / or the doping element A.

[0026] In the case of the positive active material according to the first aspect of this application, the coating of the surface of Li x Ni y Co z M k Me p O r A mthe direct contact between Li x Ni y Co z M k Me p O r A m and the electrolyte, and reduce side reactions between the positive active material and the electrolyte. Preferably, a coating element in the top layer is selected from one or a combination of several of the elements Al, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P. Even more preferably, a coating element in the top layer is selected from a combination of two or more of the elements Al, Ba, Zn, Ti, Co, W, Y, Si, Sn, B, and P.

[0027] Preferably, the topcoat contains an oxide of the aforementioned coating element. Preferably, the topcoat contains oxides consisting of two or more of the aforementioned coating elements. If the topcoat contains oxides formed by at least two coating elements, the stability of the adhesion of the topcoat to the surface of Li x Ni y Co z M k Me p O r A m to improve the surface layer so that it has a certain degree of ionic and electronic conductivity, thereby reducing the effects of the surface layer on the polarization of the positive active material.

[0028] In the positive active material in the first aspect of this application, the particle size D is fulfilled. n 10 of the positive active material, measured in µm, and a particle size D v10 of the positive active material, measured in µm, the following conditions 1≤D n 10×D v 10≤20. Preferably, the particle size D is sufficient. 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: 2≤D n 10×D v 10≤18. D v 10 is a corresponding particle size when a cumulative volume distribution percentage of the positive active material reaches 10%, and D n A particle size of 10 is corresponding when the cumulative volume fraction of the positive active material reaches 10%. If the product of D n 10 and D vIf 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 reducing the gassing problem of the positive active material while simultaneously ensuring that the volumetric energy density of the electrochemical energy storage is relatively high.

[0029] Preferably the particle size D v 10 of the positive active material 2 µm to 8 µm. Preferably the particle size D v 10 of the positive active material 3 µm to 6 µm.

[0030] For the positive active material according to the first aspect of this application, 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 conditions: 0.8≤(BET2-BETi) / BET1≤5.5.

[0031] The theoretical specific surface area of ​​the positive active material BET1=6 / (ρ×D) v 50). p is the actual density of the positive active material, measured in g / cm³ 3 . D v 50 is the corresponding particle size when the cumulative volume fraction of the positive active material reaches 50%, measured in µm.

[0032] The actual specific surface area BET2 of the positive active material can be measured using the N2 adsorption method. Details can be found in GB / T 19587-2004.

[0033] In this application, (BET2-BET1) / BET1 represents the degree of deviation between the theoretical specific surface area and the actual specific surface area of ​​the positive active material, thus allowing the measurement of surface roughness. Monitoring the degree of deviation between the theoretical and actual specific surface area of ​​the positive active material within a given range can ensure that the surface of the positive active material is relatively flat and exhibits fewer irregularities in relation to the morphology of the secondary particles, and can indicate that the primary particles from which the secondary particles are composed exhibit good particle size uniformity.This is helpful to reduce the polarization of the positive active material, improve ion transport performance, further reduce gas production, and optimize dynamic performance.

[0034] Preferably, the actual specific surface area BET2 of the positive active material is 0.1 m². 2 / g up to 0.8 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 and the positive active material is relatively small. This helps to prevent side reactions, avoid corrosion damage of the electrolyte to the crystal structure of the positive active material, and thus prevent an exacerbation of the gassing problem of the electrochemical energy storage device. Furthermore, if the actual specific surface area of ​​the positive active material lies within the aforementioned range, it is beneficial to achieve relatively strong adhesion of the binder and the conductive agent to the positive active material with fewer additives when mixing a positive paste. This contributes to increasing the energy density of the electrochemical energy storage device.

[0035] Preferably the particle size D v50 of the positive active material 5 µm to 8 µm. Preferably the particle size D v 50 of the positive active material 8 µm to 15 µm.

[0036] Preferably the particle size D v 90% of the positive active material is 10 µm to 30 µm. Preferably, the particle size D is... v 90 of the positive active material 12 µm to 25 µm.

[0037] For the positive active material according to the first aspect of this application, the differential particle size distribution curve of the positive active material preferably exhibits a single peak. The differential particle size distribution curves include both a differential volume-based particle size distribution curve and a differential number-based particle size distribution curve.

[0038] The following describes a process for producing the positive active material according to the second aspect of this application, which is used to produce the positive active material in the first aspect of this application. The process comprises the following steps: mixing 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 in a mixing device. Subsequently, the resulting mixture is sintered in an atmosphere furnace. After completion of the sintering process, staged sieving is carried out to obtain the positive active material.

[0039] The type of staged sieving is not subject to any particular restrictions and can be selected according to the actual circumstances. Preferably, staged sieving is carried out as airflow-staged sieving or as a screen-based sieve process.

[0040] A specific method of airflow-stage sieving is as follows: The sintered material is placed in an airflow classifier and then ejected through a nozzle by an airflow at a specific pressure. The particles are separated according to their size, based on the principle that particles of different sizes have different weights: A lighter particle travels a shorter distance, while a heavier particle travels a farther. The distance between a collector and the nozzle is adjusted to find particles of a suitable size, thus yielding the positive active material.

[0041] A specific method of the sieve-based sieving process is as follows: The sintered material is sieved using a 200- to 1000-mesh sieve. Due to the varying particle sizes, smaller particles pass through the sieve, while larger particles are retained, thus yielding the desired active material. Preferably, the sieve has a mesh size of 500 to 800.

[0042] The ternary material precursor can include, among other things: Ni 1 / 3 Co 1 / 3 Mn 1 / 3 (OH)2, Ni 0,5 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 0,75 Co 0,1 Mn 0,15 (OH)2, Ni0,8 Co 0,1 Mn 0,1 (OFI)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.

[0043] The Li-containing compound may comprise one or a combination of several of the compounds LiOH·H2O, LiOH, Li2CO3, and Li2O, but is not limited to them.

[0044] The compound containing the doping element Me can be an oxide, a nitrate or a carbonate or a combination of several of these, containing at least one element from Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W and Nb.

[0045] The compound containing the doping element A may include one or a combination of several of the elements LiF, NaCl, Na2S and Li3N, but is not limited to them.

[0046] The conditions for sintering can be 700 °C to 800 °C and an oxygen concentration of ≥ 20%.

[0047] The following describes another method for producing the 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. The method comprises the following steps: S1. Mix 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 in a mixing device and sinter the resulting mixture primarily in an atmosphere furnace. S2. Mix the primarily sintered material and a mixture containing the coating element in the mixing device and then secondarily sinter the resulting mixture in the atmosphere furnace. S3. Perform staged sieving of the secondarily sintered material to obtain the positive active material.

[0048] The type of staged sieving is not specifically limited and can be chosen depending on the situation. Preferably, staged sieving is carried out as airflow-staged sieving or as a screen-based sieve process.

[0049] A specific airflow-stage sieving process is as follows: The secondary sintered material is placed in an airflow classifier and then ejected through a nozzle by an airflow at a specific pressure. The particles are separated according to their size, based on the principle that particles of different sizes have different weights: A lighter particle travels a shorter distance, while a heavier particle travels a farther. The distance between a collector and the nozzle is adjusted to find particles of a suitable size, thus yielding the positive active material.

[0050] A specific method of the sieve-based sieving process is as follows: The secondarily sintered material is screened using a 200- to 1000-mesh sieve. Due to the varying particle sizes, smaller particles pass through the sieve, while larger particles are retained, thus yielding the desired active material. Preferably, the sieve has a mesh size of 500 to 800.

[0051] The ternary material precursor can include, among other things: 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 0,33 Co 0,13 Mn 0,3 (OH)2, Ni 0,33 Co 0,1 Mn 0,33 (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 0,73 Co 0,01 Mn 0,13(OH)2, Ni 0,8 Co 0,1 Mn 0,1 (OH)2, Ni 0,88 Co 0,03 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)2:0,1A12(OH)3.

[0052] The Li-containing compound may comprise one or a combination of several of the compounds LiOH·H2O, LiOH, Li2Co3, and Li2O, but is not limited to them.

[0053] The compound containing the doping element Me can be an oxide, a nitrate or a carbonate or a combination of several of these, containing at least one element from Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W and Nb.

[0054] The compound containing the doping element A may include one or a combination of several of the elements LiF, NaCl, Na2S and Li3N, but is not limited to them.

[0055] The compound containing the coating element can be an oxide, a nitrate, a phosphate, or a carbonate, or a combination of several of these, 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 between 0.01% and 0.5% of the total mass of the positive active material.

[0056] The conditions for primary sintering can be 700 °C to 800 °C and an oxygen concentration of ≥ 20%.

[0057] One condition for secondary sintering can be between 200 °C and 700 °C.

[0058] Next, the positive electrode plate is described according to the fourth aspect of this application. The positive electrode plate comprises a positive current collector and a positive membrane, which is provided on at least one surface of the positive current collector and which contains the positive active material according to the first aspect of this application.

[0059] In the case of the positive electrode plate according to the fourth aspect of this application, the positive membrane can be arranged on one surface of the positive current collector or on two surfaces of the positive current collector.

[0060] In the positive electrode plate, as described in the fourth aspect of this application, the positive membrane may also contain a conductive agent and a binder. The types and amounts of the conductive agent and binder are not specifically limited and can be selected according to the actual requirements. The binder typically consists of a fluorinated polyolefin binder. Water is generally a good solvent for the fluorinated polyolefin binder; that is, the fluorinated polyolefin binder is usually highly water-soluble. The fluorinated polyolefin binder may include, for example, polyvinylidene fluoride (PVDF), vinylidene fluoride copolymer, or a modified derivative thereof (e.g., modified with carboxylic acid, acrylic acid, or acrylonitrile), or similar materials.The conductive medium can consist of various conductive materials suitable for electrochemical energy storage according to the prior art, including, but not limited to, one or a combination of several of the following substances: carbon black, conductive carbon black, carbon fiber, carbon nanotube, and Kettjen carbon black. In the case of the positive electrode plate according to the fourth aspect of this application, the positive current collector is not limited to a specific type and can be selected according to the actual requirements. The positive current collector can typically be a layer, and the positive current collector is typically a structure or component capable of collecting current. The positive current collector can be made of various materials that can be used as the positive current collector of the electrochemical energy storage device according to the prior art.The positive current collector can be, for example, a metal foil, in particular a nickel or aluminum foil, but is not limited to that.

[0061] Next, the electrochemical energy storage device will be described according to the fifth aspect of this application. The electrochemical energy storage device contains the positive active material from the first aspect of this application.

[0062] Regarding 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. While the examples in this application only provide one instance where the electrochemical energy storage device is a lithium-ion battery, this application is not limited to this.

[0063] The electrochemical energy storage device in the fifth aspect of this application can comprise a positive electrode plate, a negative electrode plate, a separator arranged between the positive and negative electrode plates, and an electrolyte. The positive electrode plate is the positive electrode plate in the fourth aspect of this application, and the positive electrode plate contains the positive active material in the first aspect of this application.

[0064] 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 a layer that can be cut to a target size and then stacked sequentially, which can also be wound to a target size to form an electrode assembly, and which can further be combined with an electrolyte to form an electrochemical energy storage device.

[0065] In the electrochemical energy storage device, the negative electrode plate typically comprises a negative current collector and a negative active material layer located on a surface of the negative current collector. The negative active material layer usually contains a negative active material. This negative active material can be various materials suitable for the electrochemical energy storage device according to the prior art, including, but not limited to, one or a combination of several of the following materials: graphite, soft carbon, hard carbon, carbon fibers, mesophasic carbon microspheres, silicon-based material, tin-based material, lithium titanate, and any other metal that can form an alloy with lithium.The graphite can be selected from one or more combinations 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 current collector is typically a structure or component that collects a current. The negative current collector can be made of various materials that, according to the state of the art, can be used as the negative current collector of the electrochemical energy storage device. The negative current collector can, for example, be made of...It may include, but is not limited to, a metal foil; in particular, it may include, but is not limited to, a copper foil.

[0066] In electrochemical energy storage, the negative electrode plate can also be a lithium plate.

[0067] In electrochemical energy storage, the separator can consist of various materials that are suitable as a separator for electrochemical energy storage according to the state of the art, e.g. including, but not limited to, one or a combination of several of the following materials: polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester and natural fiber.

[0068] In an electrochemical energy storage device, the electrolyte can consist of various electrolytes suitable for electrochemical energy storage according to the state of the art. The electrolyte typically contains an electrolyte and a solvent, and the electrolyte can generally contain a lithium salt. More specifically, the lithium salt can be an inorganic lithium salt and / or an organic lithium salt and can, in particular, include or be a combination of LiPF6, LiBF4, LiN(SO2F)2 (LiFSI), LiN(CF3SO2)2 (LiTFSI), LiClO4, LiAsF6, LiB(C2O4)2 (LiBOB), and LiBF2C2O4 (LiDFOB). For example, the electrolyte concentration can range from 0.8 mol / L to 1.5 mol / L. The solvent can be various solvents suitable for electrolyte use in an electrochemical energy storage device according to the state of the art.The solvent of the electrolyte is generally a non-aqueous solvent, preferably an organic solvent, and may in particular include, but is not limited to, ethylene carbonate, propylene carbonate, 2,3-butylene carbonate, prenyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate and a halogenated derivative thereof.

[0069] 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 within the outer packaging. An electrolyte may be used that is infiltrated into the electrode assembly. The electrochemical energy storage device may contain one or more electrode assemblies, with the number of electrode assemblies being adjustable as required.

[0070] In some embodiments, the outer packaging of the electrochemical energy storage device can be a soft package, such as 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 also be a hard shell, such as an aluminum casing.

[0071] This application does not contain any specific 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. As an example, it shows an electrochemical energy storage device 5 with a square structure.

[0072] In some embodiments, the electrochemical energy storage device can be assembled into a battery module, and the battery module can contain a variety of electrochemical energy storage devices. The specific number can be adjusted depending on the application and the capacity of the battery module.

[0073] Fig. shows, as an example, battery module 4. As in Fig. As shown, several electrochemical energy storage devices 5 can be arranged longitudinally within the battery module 4 or in another manner. Furthermore, the majority of the electrochemical energy storage devices 5 can be secured using a fastening element.

[0074] Optionally, the battery module 4 can also include a housing with a receiving space, and the multitude of electrochemical energy storage devices 5 are housed in the receiving space.

[0075] In some embodiments, the aforementioned battery module can be assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted depending on the use and capacity of the battery pack.

[0076] Fig. and Fig. They show, as an example, a battery set 1. As in Fig. and Fig. As shown, the battery pack 1 can comprise a battery box and a plurality of battery modules 4 arranged within the battery box. The battery box consists of 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 within the battery box in any desired configuration.

[0077] Finally, the device is described according to the sixth aspect of this application, wherein the device includes the electrochemical energy storage device according to the fifth aspect of this application, and the electrochemical energy storage device can serve as the device's power supply or as its energy storage unit. The device includes, but is not limited to, 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. The electric railway, the ship, and the satellite are also carriers of tools and are considered vehicles in a broader sense.

[0078] An electrochemical energy storage device, a battery module, or a battery pack can be selected for the device according to the usage requirements for the device.

[0079] Fig. This shows an example of a device. The device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, or similar. To meet the high performance and high energy density requirements of the device for an electrochemical energy storage system, a battery pack or battery module can be used.

[0080] The following section describes this application in more detail using exemplary embodiments. It goes without saying that these exemplary embodiments serve only to describe this application and not to limit its scope.

[0081] The lithium-ion batteries in examples 1 to 8 and comparison examples 1 and 2 were all manufactured according to the following procedure. (1) Production of a positive active material

[0082] Ternary material precursors Ni 0,8 Co 0,1 Mn0,1 (OH)2, LiOH·H2O, and ZrO2 were mixed in a molar ratio of 0.997:1.05:0.003 in a mixer and subsequently sintered in an oxygen-filled atmosphere furnace. After completion of the sintering, staged sieving was carried out to find a suitable particle size and thus obtain a positively active material Li(Ni). 0,8 Co 0,1 Mn 0,1 ) 0,997 Zr 0,003 to obtain O2. (2) Preparation of a positive electrode plate

[0083] The active positive material, a polyvinylidene fluoride binder, and an acetylene 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 paste. The positive paste was applied evenly to a 12 µm thick aluminum foil of a positive current collector. The aluminum foil was dried at room temperature and then placed in an oven at 100–130 °C for further drying, followed by cold pressing and cutting to obtain a positive electrode plate. (3) Preparation of a negative electrode plate

[0084] A negatively active material (graphite), a thickener (sodium carboxymethylcellulose), a binder (styrene-butadiene rubber), and a conductive agent (acetylene black) were mixed in a mass ratio of 97:1:1:1. Deionized water was added, and the mixture was stirred with a vacuum mixer to obtain a negative paste. The negative paste was applied evenly to an 8 µm thick copper foil. The copper foil was dried at room temperature and then placed in an oven at 100–130 °C for further drying, followed by cold pressing and cutting to obtain a negative electrode plate. (4) Production of an electrolyte

[0085] An organic solvent consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 20:20:60 was used. In a glovebox with an argon atmosphere and a water content of less than 10 ppm, the fully dried lithium salt LiPF6 was dissolved in the organic solvent and mixed uniformly to obtain an electrolyte with a lithium salt concentration of 1 mol / L. (5) Preparation of a separator

[0086] A 12 µm thick polypropylene membrane was used as a separator. (6) Production of a lithium-ion battery

[0087] The positive electrode plate, separator, and negative electrode plate were stacked sequentially, with the separator positioned 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 was then injected, and the assembly was subsequently sealed. Following this, steps such as settling, hot and cold pressing, chemical conversion, fixation, and capacity sorting were performed to produce a lithium-ion battery.

[0088] The lithium-ion battery in Example 9 was manufactured using the following method. (1) Production of a positive active material

[0089] The ternary material precursors Ni 0,8 Co 0,1 Mn 0,1 (OH)2, Lio H-H₂O and ZrO₂ were mixed in a molar ratio of 0.997:1.05:0.003 in a mixer and then primarily sintered in an oxygen-filled atmosphere furnace. The primarily sintered material and 0.5 wt% Al₂O₃ were mixed in the mixing device and then secondarily sintered in the atmosphere furnace. Subsequently, a staged sieving of the secondarily sintered material was carried out to find a suitable particle size, resulting in a positively active material Li(Ni). 0,8 Co 0,1 Mn 0,1 ) 0,997 Zr 0,003 O2 was obtained, the surface of which was coated with Al2O3. (2) Preparation of a positive electrode plate

[0090] The active positive material, a polyvinylidene fluoride binder, and an acetylene 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 paste. The positive paste was applied evenly to a 12 µm thick aluminum foil of a positive current collector. The aluminum foil was dried at room temperature and then placed in an oven at 100–130 °C for further drying, followed by cold pressing and cutting to obtain a positive electrode plate. (3) Preparation of a negative electrode plate

[0091] A negatively active material (graphite), a thickener (sodium carboxymethylcellulose), a binder (styrene-butadiene rubber), and a conductive agent (acetylene black) were mixed in a mass ratio of 97:1:1:1. Deionized water was added, and the mixture was stirred with a vacuum mixer to obtain a negative paste. The negative paste was applied evenly to an 8 µm thick copper foil. The copper foil was dried at room temperature and then placed in an oven at 100–130 °C for further drying, followed by cold pressing and cutting to obtain a negative electrode plate. (4) Production of an electrolyte

[0092] An organic solvent consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio of 20:20:60 was used. In a glovebox with an argon atmosphere and a water content of less than 10 ppm, the fully dried lithium salt LiPF6 was dissolved in the organic solvent and mixed uniformly to obtain an electrolyte with a lithium salt concentration of 1 mol / L. (5) Preparation of a separator

[0093] A 12 µm thick polypropylene membrane was used as a separator. (6) Production of a lithium-ion battery

[0094] The positive electrode plate, separator, and negative electrode plate were stacked sequentially, with the separator positioned 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 was then injected, and the assembly was subsequently sealed. Following this, steps such as settling, hot and cold pressing, chemical conversion, fixation, and capacity sorting were performed to produce a lithium-ion battery.

[0095] A lithium-ion battery of Example 10 was produced by a similar process to the process for producing the lithium-ion battery in Example 9, with the difference that in Example 10, Al2O3 of 0.5 wt.% was replaced by B2O3 of 0.5 wt.%.

[0096] A test procedure for lithium-ion batteries is then described. (1) Determination of the residual lithium content on a surface of the positive active material

[0097] 30 g of powder of the prepared positive active material were taken and added to 100 ml of water and stirred for 30 minutes. Residual lithium in the sample under investigation 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 resulting from a change in potential. (2) Cycle stability test for the lithium-ion battery at high temperature

[0098] At 45 °C, the lithium-ion battery was charged to 4.2 V at a constant current of 1C. It was then charged at a constant current of 0.05 C at 4.2 V and discharged to a final voltage of 2.8 V at a constant current of 1C. The discharge capacity of the first cycle was recorded. Further charge and discharge cycles were then performed according to the aforementioned procedures until the capacity had decreased to 80% of the original capacity. The number of cycles at this point corresponded to the lifespan of the high-temperature cycles. (3) Testing the shelf life of the lithium-ion battery at high temperatures

[0099] At 25 °C, the lithium-ion battery was first charged to 4.2 V with a constant current of 1 C and then to 0.05 C with a constant voltage of 4.2 V. The volume of the lithium-ion battery was then measured using a discharge method and recorded as the initial volume. The lithium-ion battery was then stored at 80 °C for 10 days. Afterward, the volume of the lithium-ion battery was measured again using the drainage method and recorded as the volume of the lithium-ion battery after 10 days of storage at 80 °C.

[0100] Volume swelling rate (%) of the lithium-ion battery after 10 days of storage at 80 °C = [Volume of the lithium-ion battery after 10 days of storage at 80 °C / Initial volume of the lithium-ion battery-1]×100%. (4) Capacity test for the positive active material of the lithium-ion battery

[0101] The lithium-ion battery was held at rest for 2 hours in a constant temperature environment of 25 °C, then charged at 1 / 3 C from 2.8 V to 4.2 V, then charged at a constant voltage of 4.2 V with a current of no more than 0.05 mA, held at rest for 5 minutes, and then discharged at 1 C to 2.8 V. The capacity of the lithium-ion battery at this point 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 0,5 5,0 9 0,8 4,6 / Example 2 1,5 7,5 14 0,5 4,5 / Example 3 1,8 5,1 16 0,18 1,3 / Example 4 1,5 3,4 8 0,34 1,1 / Example 5 2,5 5,6 12 0,5 3,7 / Example 6 3,0 6,0 18 0,35 3,9 / Example 7 1,5 7,5 16 0,49 5,1 / Example 8 0,5 2,0 5 0,48 0,9 / Example 9 1,1 3,7 11 0,55 3,7 Al2O3 Example 10 2,4 4,8 13 0,45 3,6 B2O3 Comparison example 1 0,2 2,5 10 0,6 3,7 / Comparison example 2 4 4,4 10 0,5 2,9 / Table 2 Results of the performance tests for examples 1 to 10 and comparison examples 1 and 2 Li2CO3 content (ppm) LiOH content (ppm) Capacity of the positive active material (mAh / g) Number of cycles at 45 °C Volume swelling rate after 10 days of storage at 80 °C Example 1 2354 3451 196 1232 99% Example 2 2234 3612 195 1182 94 % Example 3 2131 3588 194 1124 93 % Example 4 2554 3821 196 1198 95 % Example 5 2764 3353 196 1218 89% Example 6 2481 3221 194 1198 87 % Example 7 2341 4312 . 194 854 105 % Example 8 2651 4231 196 989 115 % Example 9 2412 1831 195 1287 78 % Example 10 1531 1952 196 1098 86 % Comparative example 1 3452 4525 194 894 154 % Comparative example 2 2324 3821 192 951 125 %

[0102] The analysis of the test results in Table 2 shows that the positive active materials for the lithium-ion batteries of examples 1 to 10 contained a low relative amount of micropowder with a particle size of less than 1 µm and exhibited a higher capacity. Furthermore, the lithium-ion battery had a longer high-temperature cycle life and a lower swelling rate of the storage volume at high temperatures.Therefore, adequate control of the particle morphology of the positive active material and the amount of micropowder in the positive active material could effectively reduce the side reactions between the positive active material and the electrolyte, decrease the gas production of the lithium-ion battery, and improve the storage performance of the lithium-ion battery without affecting the energy density, cycle stability, and rate performance of the lithium-ion battery.

[0103] Further analysis of the test results from examples 1 to 8 also revealed that controlling the degree of deviation between the theoretical specific surface area BET1 and the actual specific surface area BET2 of the positive active material allows for further optimization of the positive active material's microstructure, ensuring a relatively flat surface with fewer irregularities. This helped to reduce the polarization of the positive active material and improve ion transport, thereby further reducing gas production in the lithium-ion battery and optimizing its kinetic performance.

[0104] In comparison to Example 1, the positive active material in Examples 9 and 10 was Li(Ni). 0,8 Co 0,1 Mn 0,1 ) 0,997 Zr 0,003O2 with a coating on the surface. The coating of the surface of Li(Ni). 0.8 Co 0,1 Mn 0,1 ) 0.997 Zr 0.003 O2 could prevent direct contact between Li(Ni) 0,8 Co 0,1 Mn 0,1 ) 0.997 Zr 0,003 Avoiding O2 and the electrolyte and reducing the likelihood of side reactions between the positive active material and the electrolyte. Furthermore, a cover layer of Al2O3 and B2O3 exhibited good ionic and electronic conductivity, which mitigated the problem of gas formation while minimizing the cover layer's effect on the polarization of the positive active material.

[0105] In comparative example 1, D n 10 of the positive active material is further reduced. From the differential volume-based particle size distribution curve and the differential number-based particle size distribution curve in Fig. and Fig.It is evident that the particle size distribution curves of the positive active material each exhibit two peaks. One possible reason was an excessively high relative proportion of micropowder in the positive active material. Referring to Fig. and Fig.It can be seen 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, indicating a low relative amount of micropowder in the positive active material. If the relative amount of micropowder in the positive active material were too high because the specific surface area of ​​the micropowder was larger, the amount of residual lithium on the surface would be greater, and the contact area with the electrolyte would be larger. Therefore, more side reactions would occur when the positive active material comes into contact with the electrolyte.In order to maintain charge balance, Micro-Power's positive active material 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.

[0106] In comparative example 2, the D was n 10 of the positive active material 4 µm. In this case, the proportion of micropowder in the positive active material was lower, but due to the fact that D vSince the particle size distribution had to be kept within a specific range of 50 to maintain good ion transport, the particle size distribution of the positive active material was narrow, and many pores were present between the particles of the positive active material in the positive electrode plate, making it difficult to achieve a high compaction density. Furthermore, cold pressing the positive electrode plate tends to break down the particles of the positive active material, which can not only negatively affect the energy density of the lithium-ion battery but also exacerbate swelling.

Claims

[1] A positive active material, wherein the positive active 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 m is, whose surface is provided with a top layer, where 0.85≤x≤1.15, 0 <y<1, 0<z<1, 0<k<1, 0≤p≤0, 1≤r≤2, 0≤m≤1, m+r≤2, M ausgewählt ist aus einem oder zwei von Mn und Al, Me mindestens ein Element von Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, Sr, Sb, Y, W und Nb enthält und A einschließt, aber nicht beschränkt ist auf eines oder eine Kombination von mehreren von N, F, S und Cl; und The positive active material consists of secondary particles, and the particle size D n 10 of the positive active material meets the conditions: 0.5 µm≤D n 10≤3 µm. [2] Positive active material according to claim 1, wherein the particle size D n10 of the positive active material is fulfilled: 1 µm≤D n 10≤2 µm. [3] Positively active material according to claim 1, wherein a coating element in the top layer is selected from one or more of Al, Ba, Zn, Ti, Co, W, Y, Si, Sn, B and P. [4] Positive active material according to any one of claims 1 to 3, wherein 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, meet: 1≤ D n 10×D v 10≤20, and D v A particle size of 10 is reached when the percentage of the cumulative volume distribution of the positive active material reaches 10%. [5] Positive active material according to claim 1 or 4, wherein the particle size D v 10 of the positive active material is 2 µm to 8 µm, preferably 3 µm to 6 µm. [6] Positive active material according to any one of claims 1 to 5, 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: 0.8≤(BET2-BET1) / BETi≤5.5, where BET1=6 / (ρ×Dv50); ρ is the actual density of the positive active material, measured in g / cm³ 3 ; and D v 50 is the corresponding particle size when the cumulative volume fraction of the positive active material reaches 50%, measured in µm. [7] Positive active material according to claim 6, wherein the actual specific surface area BET2 of the positive active material is 0.1 m² 2 / g up to 0.8 m 2 / g. [8] Positive active material according to claim 6, wherein the particle size D v 50 of the positive active material is 5 µm to 18 µm, preferably 8 µm to 15 µm. [9] Positive active material according to any one of claims 1 to 8, wherein a differential particle size distribution curve of the positive active material has one and only one peak. [10] A positive electrode plate containing the positive active material according to any one of claims 1 to 8. [11] An electrochemical energy storage device comprising the positive active material according to any one of claims 1 to 9. [12] A device, wherein the device is a vehicle and comprises the electrochemical energy storage device according to claim 11.

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