A single-crystal ternary cathode material, a manufacturing method thereof, and a lithium-ion battery

Abstract

An embodiment of the present application provides a single-crystalline ternary cathode material, a manufacturing method thereof, and a lithium-ion battery, including: mixing a ternary precursor, a lithium salt, and an additive uniformly and performing a first calcination to obtain a first material. The additive at least includes a halogen anion X, that is, the halogen anion X is introduced by the first calcination. Mixing the first material and the additive uniformly and performing a second calcination to obtain the single-crystalline ternary cathode material. The additive at least includes a target cation Q with an ionic radius greater than or equal to a threshold value, that is, the target cation Q with a larger ionic radius is introduced by the second calcination. While entering the crystal lattice, it forms a surface coating, so that the formed single-crystalline ternary cathode material includes the halogen anion X and the target cation Q, in order to improve the crystal structure stability of the formed single-crystalline ternary cathode material by using the halogen anion X and the target cation Q, and finally improve the transport performance and electrochemical performance of the single-crystalline ternary cathode material.

Description

Technical Field

[0001] The present invention relates to the field of batteries, and particularly to a single-crystalline ternary cathode material, a manufacturing method thereof, and a lithium-ion battery. Background Art

[0002] With the development of society, the increasing demand for energy and the continuous consumption of energy are promoting the research on renewable energy. Among renewable energy sources, lithium-ion batteries are widely used in electric vehicles, electronic devices, energy storage and other fields due to their advantages such as high volume / mass energy density, no memory effect, safety and environmental protection. Among the components of lithium-ion batteries, the cathode material plays a crucial role.

[0003] In recent years, ternary cathode materials have attracted wide attention in the industry due to their high discharge specific capacity, high energy density and low cost. Currently, the most studied and widely used ternary cathode material is a secondary spherical polycrystalline material formed by the stacking and aggregation of primary particles. However, during the actual charge and discharge process of the battery, the polycrystalline material will undergo a phase change, resulting in a rapid decline in the battery performance. Since the single-crystalline ternary cathode material has no grain boundaries and uniform stress distribution, it can avoid the problems existing in polycrystalline materials.

[0004] However, the currently manufactured single-crystalline ternary cathode material has the disadvantage of poor electrochemical performance. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a single-crystalline ternary cathode material, a manufacturing method thereof, and a lithium-ion battery, which can manufacture a single-crystalline ternary cathode material with good transport performance and electrochemical performance.

[0006] To achieve the above purpose, this application has the following technical solutions:

[0007] The embodiment of this application provides a manufacturing method of a single-crystalline ternary cathode material, including:

[0008] Mixing a ternary precursor, a lithium salt and an additive uniformly and performing a first roasting to obtain a first material, where the additive at least includes a halogen anion X;

[0009] Mixing the first material and an additive uniformly and performing a second roasting to obtain a single-crystalline ternary cathode material, where the additive at least includes a target cation Q with an ionic radius greater than or equal to a threshold value, and the single-crystalline ternary cathode material at least includes the halogen anion X and the target cation Q.

[0010] Optionally, the method further includes:

[0011] Forming a coating layer that coats the single-crystalline ternary cathode material, where the coating layer at least includes the target cation Q.

[0012] Optionally, the additive is a lithium compound corresponding to the halogen anion X.

[0013] Optionally, the additive is one or more of LiF, LiCl, LiBr, and LiI.

[0014] Optionally, the molar ratio range of the halogen anion X to the metal element in the ternary precursor is (0, 0.1).

[0015] Optionally, the element of the target cation Q is one or more of Sr, Y, Ba, La, and Ce.

[0016] Optionally, the additive is one or more of the oxide, nitrate, sulfate, hydroxide, bicarbonate, and carbonate of the target cation Q.

[0017] Optionally, the molar ratio range of the target cation Q to the transition metal element in the primary material is (0, 0.05).

[0018] An embodiment of the present application provides a single-crystal ternary cathode material, which is characterized by including a matrix, and the matrix at least includes the halogen anion X and the target cation Q;

[0019] The target cation Q has an ionic radius greater than or equal to a threshold value.

[0020] Optionally, the single-crystal ternary cathode material further includes a coating layer, and the coating layer at least includes the target cation Q.

[0021] An embodiment of the present application provides a lithium-ion battery, which is characterized in that the lithium-ion battery at least includes the single-crystal ternary cathode material described in the above embodiment.

[0022] An embodiment of the present application provides a manufacturing method of a single-crystal ternary cathode material, including: uniformly mixing a ternary precursor, a lithium salt, and an additive and performing a first calcination to obtain a primary material. The additive at least includes the halogen anion X, that is, the halogen anion X is introduced by the first calcination. Then uniformly mixing the primary material and the additive and performing a second calcination to obtain the single-crystal ternary cathode material. The additive at least includes the target cation Q with an ionic radius greater than or equal to a threshold value, that is, the target cation Q with a larger ionic radius is introduced by the second calcination, so that the formed single-crystal ternary cathode material includes the halogen anion X and the target cation Q, to improve the crystal structure stability of the formed single-crystal ternary cathode material by using the halogen anion X and the target cation Q, and finally improve the transport performance and electrochemical performance of the single-crystal ternary cathode material. Description of the Drawings

[0023] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0024] Figure 1 Fig. shows a schematic flow chart of a manufacturing method of a single crystal ternary cathode material provided by an embodiment of the present application;

[0025] Figure 2 Fig. shows a schematic diagram of the crystal structure of a single crystal ternary cathode material provided by an embodiment of the present application;

[0026] Figure 3 Fig. shows a scanning electron microscope schematic diagram of a single crystal ternary cathode material provided by an embodiment of the present application;

[0027] Figure 4 Fig. shows an X-ray diffraction schematic diagram of a single crystal ternary cathode material provided by an embodiment of the present application. Detailed Embodiments

[0028] To make the above objects, features, and advantages of the present application more obvious and understandable, the following will make a detailed description of the specific embodiments of the present application with reference to the accompanying drawings.

[0029] Many specific details are set forth in the following description to facilitate a thorough understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0030] With the development of society, the increasing demand for energy and the continuous consumption of energy are both promoting the research on renewable energy. Among renewable energy sources, lithium-ion batteries are widely used in electric vehicles, electronic devices, energy storage, and other fields due to their advantages such as high volume / mass energy density, no memory effect, safety, and environmental friendliness. Among the components of lithium-ion batteries, the cathode material plays a crucial role.

[0031] In recent years, ternary cathode materials have received extensive attention in the industry due to their high discharge specific capacity, high energy density, and low cost. Currently, the most studied and widely used ternary cathode materials are secondary sphere polycrystalline materials formed by the accumulation and aggregation of primary particles. However, there are grain boundaries between primary particles in polycrystalline materials, resulting in lithium ions (Li +)The transmission is limited, and during the actual charge and discharge process of the battery, the polycrystalline material will undergo a phase change, especially the phase change of the high-nickel material from H2 to H3, resulting in the formation of microcracks and severe lattice distortion. The formation of microcracks will damage the CEI solid electrolyte interface film, leading to the exposure of more active sites, accelerating the deterioration of the material, and causing the battery performance to decline rapidly. Since the single-crystalline ternary cathode material has no grain boundaries and uniform stress distribution, it can effectively alleviate the formation of microcracks and avoid the problems existing in polycrystalline materials.

[0032] One of the current methods for manufacturing single-crystalline ternary cathode materials is to first grind and mix a new type of highly efficient composite additive with a high-nickel ternary precursor in a certain proportion, place it in a tube furnace, and use gradient calcination technology to obtain a single-crystalline high-nickel ternary intermediate with co-doping of cations and anions. Then, the intermediate is ground and mixed evenly with a lithium source and placed in a tube furnace for calcination for a period of time, and finally a highly monodisperse single-crystalline high-nickel ternary cathode material is prepared.

[0033] However, in such a manufacturing method, since the cation and anion dopants are added simultaneously, they are likely to affect each other and it is difficult to control the doping amount, resulting in the disadvantage of poor electrochemical performance of the currently manufactured single-crystalline ternary cathode materials.

[0034] Based on this, the embodiments of the present application provide a method for manufacturing a single-crystalline ternary cathode material, including: mixing a ternary precursor, a lithium salt, and an additive evenly and performing a first calcination to obtain a first material. The additive at least includes a halogen anion X, that is, the halogen anion X is introduced by the first calcination. Then, the first material and the additive are mixed evenly and subjected to a second calcination to obtain a single-crystalline ternary cathode material. The additive at least includes a target cation Q with an ionic radius greater than or equal to a threshold value, that is, the target cation Q with a larger ionic radius is introduced by the second calcination, so that the formed single-crystalline ternary cathode material includes the halogen anion X and the target cation Q, in order to improve the crystal structure stability of the formed single-crystalline ternary cathode material by using the halogen anion X and the target cation Q, and finally improve the transmission performance and electrochemical performance of the single-crystalline ternary cathode material.

[0035] To better understand the technical solutions and technical effects of the present application, the following will describe specific embodiments in detail with reference to the drawings.

[0036] Reference Figure 1 As shown, it is a schematic flowchart of a method for manufacturing a single-crystalline ternary cathode material provided by the embodiments of the present application. The method includes the following steps:

[0037] S101, mixing a ternary precursor, a lithium salt, and an additive evenly and performing a first calcination to obtain a first material.

[0038] In an embodiment of the present application, a ternary precursor, a lithium salt, and an additive can be obtained. The additive at least includes a halogen anion X. The obtained ternary precursor, lithium salt, and additive are mixed evenly and subjected to a first calcination to obtain a first calcined material.

[0039] Specifically, the ternary precursor can be synthesized by a hydroxide co - precipitation method. The chemical formula of the ternary precursor can be Ni a Co b Mn c (OH)2, where 0.50 ≤ a ≤ 0.95, 0 < b ≤ 0.20, 0 < c ≤ 0.30, and a + b + c = 1. The lithium salt can be one of Li2CO3 or LiOH·H2O. The molar ratio of Li element in the lithium salt to the total metal elements in the ternary precursor is 1.00 - 1.10.

[0040] In practical applications, after the first calcination, steps such as cooling, pulverizing, and sieving can be performed on the crystals after the first calcination to obtain the first material.

[0041] In an embodiment of the present application, the halogen anion X is introduced by using an additive during the first calcination. The halogen anion X can be F - 、Cl - 、Br - and I - , so that the halogen can enter the oxygen site of the single - crystal ternary cathode material. As shown in Figure 2 , that is, the halogen anion X can partially replace the oxygen ion. Compared with the oxygen ion, the halogen anion X has a stronger electronegativity. In the single - crystal ternary cathode material, the bond energy of the formed transition metal - halogen (TM - X) bond is stronger than that of the transition metal - oxygen (TM - O) bond. The formed TM - X bond can be used to improve the crystal structure stability of the single - crystal ternary cathode material.

[0042] Specifically, the range of the molar ratio of the halogen anion X to the metal elements in the ternary precursor is (0, 0.1). That is to say, the formation of the single - crystal ternary cathode material can be controlled by controlling the proportion of the introduced halogen anion X.

[0043] In an embodiment of the present application, the additive can be a lithium compound corresponding to the halogen anion X. The lithium compound corresponding to the halogen anion X has a fluxing effect and can assist the growth of single - crystal particles, improving the degree of single - crystallization of the single - crystal ternary cathode material.

[0044] As an example, the additive can be one or more of LiF, LiCl, LiBr, and LiI.

[0045] In the embodiments of the present application, the conditions for the first calcination are that the first calcination temperature is 700-1000 °C, the first calcination time is 8-20 h, the heating rate is 2-10 °C / min, and the calcination atmosphere is oxygen.

[0046] Specifically, after the first calcination, the chemical formula of the first material can be LiNi a Co b Mn c O 2-y / 2 X y , where 0.50 ≤ a ≤ 0.95, 0 < b ≤ 0.20, 0 < c ≤ 0.30, a + b + c = 1, and 0 < y < 0.1.

[0047] S102, mix the first material and the additive evenly and perform a second calcination to obtain a single-crystalline ternary cathode material.

[0048] In the embodiments of the present application, after the first calcination, a first material introducing a halogen anion X can be obtained. The first material and the additive can be mixed evenly and then subjected to a second calcination to obtain a single-crystalline ternary cathode material, where the additive at least includes a target cation Q with an ionic radius greater than or equal to a threshold value.

[0049] In the embodiments of the present application, during the second calcination, due to the relatively large ionic radius of the target cation Q, some of the target cation Q can be doped into the crystal structure of the single-crystalline ternary cathode material. As shown in Figure 2 , that is, some of the target cation Q enters the transition metal site of the single-crystalline ternary cathode material, which can further improve the crystal structure stability of the single-crystalline ternary cathode material. Some of the target cation Q is coated on the surface of the material in the form of an oxide, which can further enhance the stability of the single-crystalline ternary cathode at high voltages.

[0050] Specifically, the threshold value can be 0.08 nanometers (nm), that is, the ionic radius of the target cation Q is greater than or equal to 0.8 angstroms.

[0051] In the embodiments of the present application, the element of the target cation Q can be one or more of Sr, Y, Ba, La, and Ce, and the additive can be one or more of oxides, nitrates, sulfates, hydroxides, bicarbonates, and carbonates of the target cation Q.

[0052] As an example, the additive can be one or more of oxides, nitrates, sulfates, hydroxides, bicarbonates, and carbonates of Sr, Y, Ba, La, and Ce.

[0053] In an embodiment of the present application, the molar ratio range of the target cation Q to the transition metal elements in the primary material is (0, 0.05). That is to say, the formation of the single-crystal ternary cathode material can be controlled by controlling the proportion of the introduced target cation Q.

[0054] In practical applications, after the secondary calcination, steps such as cooling, roll pressing, and sieving can be performed to process the crystals after the secondary calcination to obtain the single-crystal ternary cathode material.

[0055] In an embodiment of the present application, the conditions for the secondary calcination are that the secondary calcination temperature is 600 - 850 °C, the secondary calcination time is 2 - 10 h, the heating rate is 2 - 10 °C / min, and the calcination atmosphere is oxygen.

[0056] Specifically, after the secondary calcination, the chemical formula of the single-crystal ternary cathode material can be Li(Ni a Co b Mn c ) 1-d Q d O 2-y / 2 X y , where 0.50 ≤ a ≤ 0.95, 0 < b ≤ 0.20, 0 < c ≤ 0.30, 0 < d < 0.05, a + b + c + d = 1, and 0 < y < 0.1.

[0057] In an embodiment of the present application, the halogen anion X is introduced through the primary calcination, and the target cation Q is introduced through the secondary calcination, so that the finally formed single-crystal ternary cathode material includes at least the halogen anion X and the target cation Q. That is, through two calcinations, the co-doping of anions and cations at the oxygen site and the transition metal site is realized to improve the stability of the lattice structure of the single-crystal ternary cathode material.

[0058] In an embodiment of the present application, during the secondary calcination, due to the relatively large ionic radius of the target cation Q, in addition to entering the lattice structure of the single-crystal ternary cathode material to improve the stability of the lattice structure, part of the target cation Q can also form a coating layer on the surface of the single-crystal ternary cathode material. That is to say, while the target cation Q is being doped, the surface coating of the single-crystal ternary cathode material is also realized. Specifically, the coating layer can be an oxide of the target cation Q.

[0059] That is to say, the coating layer formed by the target cation Q can modify the surface state of the single-crystal ternary cathode material, alleviate the side reaction between the single-crystal ternary cathode material and the electrolyte, improve the electrochemical performance of the single-crystal ternary cathode material, and improve the cycling performance of the single-crystal ternary cathode material at high voltages.

[0060] Refer to Figure 3 and Figure 4 as shown.Figure 3 Schematic diagram of a scanning electron microscope (SEM) of a single-crystal ternary cathode material provided by an embodiment of the present application Figure 4 Schematic diagram of X-ray diffraction (XRD) of a single-crystal ternary cathode material provided by an embodiment of the present application. It can be seen from Figure 3 that the degree of single crystallization of the single-crystal ternary cathode material is good, the particles are evenly dispersed, and there is a coating substance on the surface. It can be seen from Figure 4 that the crystallinity of the single-crystal ternary cathode material is good, which can be indexed as a hexagonal layered structure, and no obvious impurity phases are found.

[0061] The manufacturing method of the single-crystal ternary cathode material provided by the embodiment of the present application will be specifically introduced below by adjusting the halogen anion X and the target cation Q introduced in the first roasting and the second roasting and the roasting conditions:

[0062] The first embodiment is to grind and mix the ternary precursor Ni 0.63 Co 0.07 Mn 0.30 (OH)2, lithium salt LiOH·H2O and additive LiF evenly. The molar ratio of Li in LiOH·H2O to the total metal elements in the ternary precursor is 1.04, and the molar ratio of F in LiF to the total metal elements in the ternary precursor is 0.02. Perform the first roasting in an oxygen atmosphere. The first roasting temperature is 930 °C, the first roasting time is 15 h, and the heating rate is 3.0 °C / min. After roasting, cool, crush and screen to obtain the first material, and its chemical formula is LiNi 0.63 Co 0.07 Mn 0.30 O 1.99 F 0.02 . Grind and mix the first material with the additive Y(OH)3 evenly. The molar ratio of Y in the additive to the total transition metal elements in the first material is 0.01. Perform the second roasting in an oxygen atmosphere. The roasting temperature is 750 °C, the roasting time is 5 h, and the heating rate is 5 °C / min. After roasting, cool, roll and screen to obtain the ternary single-crystal cathode material. The coating substance on the surface of this material is yttrium oxide, and its chemical formula is Li(Ni 0.63 Co 0.07 Mn 0.30 ) 0.99 Y 0.01 O 1.99 F 0.02 .

[0063] The second embodiment is to use the ternary precursor Ni 0.68 Co 0.05 Mn 0.27(OH)2, LiOH·H2O and LiCl are ground and mixed thoroughly. The molar ratio of Li in LiOH·H2O to the total metal elements in the ternary precursor is 1.02, and the molar ratio of Cl in LiCl to the total metal elements in the ternary precursor is 0.04. A first calcination is carried out in an oxygen atmosphere. The first calcination temperature is 920 °C, the first calcination time is 13 h, and the heating rate is 2.5 °C / min. After the calcination is completed, it is cooled, crushed and sieved to obtain the first material, whose chemical formula is LiNi 0.68 Co 0.05 Mn 0.27 O 1.98 Cl 0.04 . The first material and the additive La(NO3)3 are ground and mixed thoroughly. The molar ratio of La in the additive to the total transition metal elements in the first material is 0.03. A second calcination is carried out in an oxygen atmosphere. The calcination temperature is 820 °C, the calcination time is 4 h, and the heating rate is 5 °C / min. After the calcination is completed, it is cooled, roll-pressed and sieved to obtain the ternary single-crystal cathode material. The surface coating substance of this material is lanthanum oxide compound, and its chemical formula is Li(Ni 0.68 Co 0.05 Mn 0.27 ) 0.97 La 0.03 O 1.98 Cl 0.04 .

[0064] In the third embodiment, the ternary precursor Ni 0.75 Co 0.05 Mn 0.20 (OH)2, LiOH·H2O and LiBr are ground and mixed thoroughly. The molar ratio of Li in LiOH·H2O to the total metal elements in the ternary precursor is 1.01, and the molar ratio of Br in LiBr to the total metal elements in the ternary precursor is 0.03. A first calcination is carried out in an oxygen atmosphere. The first calcination temperature is 900 °C, the first calcination time is 10 h, and the heating rate is 3.0 °C / min. After the calcination is completed, it is cooled, crushed and sieved to obtain the first material, whose chemical formula is LiNi 0.75 Co 0.05 Mn 0.20 O 1.985 Br 0.03 . The first material and the additive BaSO4 are ground and mixed thoroughly. The molar ratio of Ba in the additive to the total transition metal elements in the first material is 0.02. A second calcination is carried out in an oxygen atmosphere. The calcination temperature is 680 °C, the calcination time is 8 h, and the heating rate is 5 °C / min. After the calcination is completed, it is cooled, roll-pressed and sieved to obtain the ternary single-crystal cathode material. The surface coating substance of this material is barium oxide compound, and its chemical formula is Li(Ni 0.75 Co 0.05Mn 0.20 ) 0.98 Ba 0.02 O 1.985 Br 0.03 。

[0065] The fourth embodiment is to grind and mix evenly the ternary precursor Ni 0.80 Co 0.01 Mn 0.10 (OH)2, LiOH·H2O, LiF and LiI. The molar ratio of Li in LiOH·H2O to the total metal elements in the ternary precursor is 1.01, the molar ratio of F in LiF to the total metal elements in the ternary precursor is 0.001, and the molar ratio of I in LiI to the total metal elements in the ternary precursor is 0.001. Carry out a first calcination in an oxygen atmosphere. The first calcination temperature is 860 °C, the first calcination time is 12 h, and the heating rate is 3.0 °C / min. After the calcination is completed, it is cooled, crushed and sieved to obtain the first material, and its chemical formula is LiNi 0.80 Co 0.10 Mn 0.10 O 1.99 F 0.005 I 0.005 。 Grind and mix evenly the first material with the additive SrCO3. The molar ratio of Sr in the additive to the total transition metal elements in the first material is 0.01. Carry out a second calcination in an oxygen atmosphere. The calcination temperature is 650 °C, the calcination time is 10 h, and the heating rate is 5 °C / min. After the calcination is completed, it is cooled, roll-pressed and sieved to obtain the ternary single-crystal cathode material. The surface coating material of this material is strontium oxide compound, and its chemical formula is Li(i 0.80 Co 0.10 Mn 0.10 ) 0.99 Sr 0.01 O 1.99 F 0.01 I 0.01 。

[0066] The fifth embodiment is to grind and mix evenly the ternary precursor Ni 0.85 Co 0.05 Mn 0.10 (OH)2, LiOH·H2O and LiF. The molar ratio of Li in LiOH·H2O to the total metal elements in the ternary precursor is 1.01, and the molar ratio of F in LiF to the total metal elements in the ternary precursor is 0.02. Carry out a first calcination in an oxygen atmosphere. The first calcination temperature is 830 °C, the first calcination time is 12 h, and the heating rate is 3.0 °C / min. After the calcination is completed, it is cooled, crushed and sieved to obtain the first material, and its chemical formula is LiNi 0.85 Co 0.05 Mn0.10 O 1.99 F 0.02 Mix the primary material with additives Ce(NO3)4 and Y(OH)3 by grinding to make them fully and evenly mixed. The molar ratio of Ce in the additives to the total transition metal elements in the primary material is 0.005, and the molar ratio of Y in the additives to the total transition metal elements in the primary material is 0.005. Perform secondary calcination in an oxygen atmosphere at a calcination temperature of 800 °C for a calcination time of 5 h with a heating rate of 5 °C / min. After the calcination is completed, cool, roll, and screen to obtain the ternary single-crystal cathode material. The surface coating material of the ternary single-crystal cathode material is barium oxide compound and yttrium oxide compound, and its chemical formula is Li(Ni 0.85 Co 0.05 Mn 0.10 ) 0.99 Ce 0.005 Y 0.005 O 1.99 F 0.02 。

[0067] The first comparative example is a comparative example of the first example. The difference from the first example is that halogen lithium compound LiF is not added in the primary calcination, and the rest of the steps are the same. The chemical formula of the prepared ternary single-crystal cathode material is Li(Ni 0.63 Co 0.07 Mn 0.30 ) 0.99 Y 0.01 O2, and the surface coating material of this material is also yttrium oxide compound.

[0068] The second comparative example is also a comparative example of the first example. The difference from the first example is that no additives are added in the secondary calcination, and the rest of the steps are the same. The chemical formula of the prepared ternary single-crystal cathode material is LiNi 0.63 Co 0.07 Mn 0.30 O 1.99 F 0.02 。

[0069] An embodiment of the present application provides a method for manufacturing a single-crystalline ternary cathode material, including: uniformly mixing a ternary precursor, a lithium salt, and an additive and performing a first calcination to obtain a first material. The additive at least includes a halogen anion X, that is, the halogen anion X is introduced by the first calcination. Then, uniformly mixing the first material and the additive and performing a second calcination to obtain the single-crystalline ternary cathode material. The additive at least includes a target cation Q with an ionic radius greater than or equal to a threshold value, that is, the target cation Q with a larger ionic radius is introduced by the second calcination, so that the formed single-crystalline ternary cathode material includes the halogen anion X and the target cation Q, to improve the crystal structure stability of the formed single-crystalline ternary cathode material by using the halogen anion X and the target cation Q, and finally improve the transport performance and electrochemical performance of the single-crystalline ternary cathode material.

[0070] Based on the method for manufacturing a single-crystalline ternary cathode material provided in the above embodiment, an embodiment of the present application further provides a single-crystalline ternary cathode material. The single-crystalline ternary cathode material provided in the embodiment of the present application includes a matrix, and the matrix at least includes a halogen anion X and a target cation Q, wherein the ionic radius of the target cation Q is greater than or equal to the threshold value.

[0071] Specifically, the chemical formula of the single-crystalline ternary cathode material is Li(Ni a Co b Mn c ) 1-d Q d O 2-y / 2 X y , where 0.50 ≤ a ≤ 0.95, 0 < b ≤ 0.20, 0 < c ≤ 0.30, 0 < d < 0.05, a + b + c + d = 1, 0 < y < 0.1, X is a halogen anion, and Q is a target cation Q with an ionic radius greater than or equal to the threshold value.

[0072] Optionally, the single-crystalline ternary cathode material further includes a coating layer, and the coating layer at least includes the target cation Q.

[0073] Based on the single-crystalline ternary cathode material provided in the above embodiment, an embodiment of the present application further provides a lithium-ion battery. The lithium-ion battery provided in the embodiment of the present application includes the single-crystalline ternary cathode material provided in the above embodiment.

[0074] In the embodiment of the present application, the manufactured single-crystalline ternary cathode material can be assembled into a CR2032 coin cell and subjected to electrochemical performance testing.

[0075] Specifically, the as-prepared single-crystalline ternary cathode material, acetylene black, and binder (PVDF) are weighed and mixed at a mass ratio of 90:5:5, and an appropriate amount of N-methylpyrrolidone solvent (NMP) is added to make a slurry. Then the slurry is evenly coated on an aluminum foil current collector and dried in a vacuum drying oven at 120 °C for 12 h. After drying and cooling, it is taken out, and a cathode disc with a diameter of 14 mm is cut using a slicing machine. After accurate weighing, it is transferred to a glove box filled with high-purity argon for standby. In the glove box, the cathode material is assembled into a coin cell with metallic lithium as the anode, and the electrolyte is 1 M LiPF6 solution (the solvent is V 碳酸乙烯酯 :V 碳酸甲乙酯 :V 碳酸二甲酯 =1:1:1), and the separator is Celgard 2400 microporous polypropylene membrane. The assembly sequence is anode shell, anode sheet, separator, electrolyte, lithium sheet, and cathode shell in turn. After being sealed by a sealer, a CR2032 coin cell is obtained. The assembled cell needs to be left standing at room temperature for 12 h to allow the electrolyte to fully infiltrate the electrode sheets, and then the electrochemical performance test is carried out.

[0076] Seven kinds of as-prepared single-crystalline ternary cathode materials can be assembled into CR2032 coin cells, and the electrochemical performance tests are carried out, respectively testing the first charge-discharge specific capacity, the first Coulombic efficiency, and the capacity retention rate after 30 cycles. Among them, the first capacity test conditions are 3.0 - 4.5 V at 25 °C with 0.1 C charge-discharge. The cycle test conditions are 3.0 - 4.5 V at 45 °C with 1 C charge-discharge. The test results are shown in the following table:

[0077]

[0078] As can be seen from the above table, compared with the first comparative example and the second comparative example, the first to fifth examples all have higher discharge specific capacity, first Coulombic efficiency, and cycle retention rate, which is attributed to the doping of halogen anion X into the oxygen site during the first calcination and the doping of part of the target cation Q into the transition metal site during the second calcination. Compared with oxygen ions, halogen anion X has stronger electronegativity and stronger bond energy with transition metals. In addition, the target cation Q can enter the transition metal layer of the material, thus stabilizing the crystal structure of the single-crystalline ternary cathode material and improving the electrochemical performance of the single-crystalline ternary cathode material. At the same time, part of the target cation Q coated on the surface of the single-crystalline ternary cathode material during the second calcination improves the surface state of the single-crystalline ternary cathode material, reduces the side reaction between the single-crystalline ternary cathode material and the electrolyte, and improves the cycle performance of the single-crystalline ternary cathode material at high voltages.

[0079] Each embodiment in this specification is described in a progressive manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the structural embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and reference can be made to the relevant parts of the method embodiments for the related content.

[0080] The above description is only a preferred embodiment of the present application. Although the present application has been disclosed above with preferred embodiments, it is not intended to limit the present application. Any person skilled in the art can make many possible changes and modifications to the technical solution of the present application by using the methods and technical contents disclosed above, or modify it into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present application without departing from the technical solution of the present application still fall within the scope of protection of the technical solution of the present application.

Claims

1. A manufacturing method of a single-crystal ternary cathode material, characterized in that, Comprising: Mixing a ternary precursor, a lithium salt, and an additive uniformly and performing a first calcination to obtain a first material, wherein the additive at least comprises a halogen anion X; Mixing the first material and an additive uniformly and performing a second calcination to obtain a single-crystalline ternary cathode material, wherein the additive at least comprises a target cation Q with an ionic radius greater than or equal to a threshold value, and the single-crystalline ternary cathode material at least comprises the halogen anion X and the target cation Q; the threshold value is 0.08 nm; Forming a coating layer, the coating layer coating the single-crystalline ternary cathode material, and the coating layer at least comprises the target cation Q.

2. The method according to claim 1, wherein The additive is a lithium compound corresponding to the halogen anion X.

3. The method according to claim 2, wherein The additive is one or more of LiF, LiCl, LiBr, and LiI.

4. The method according to claim 1, wherein The molar ratio range of the halogen anion X to the metal element in the ternary precursor is (0, 0.1).

5. The method according to any one of claims 1-4, characterized in that, The element of the target cation Q is one or more of Sr, Y, Ba, La, and Ce.

6. The method according to any one of claims 1-4, characterized in that, The additive is one or more of an oxide, nitrate, sulfate, hydroxide, bicarbonate, and carbonate of the target cation Q.

7. The method according to any one of claims 1 to 4, characterized in that, The molar ratio range of the target cation Q to the transition metal element in the first material is (0, 0.05).

8. A single-crystal ternary cathode material, characterized in that, The single-crystalline ternary cathode material is manufactured by using the manufacturing method of the single-crystalline ternary cathode material according to any one of claims 1-7. The single-crystalline ternary cathode material comprises a matrix, and the matrix at least comprises the halogen anion X and the target cation Q; The ionic radius of the target cation Q is greater than or equal to a threshold value; the threshold value is 0.08 nm; The single-crystalline ternary cathode material further comprises a coating layer, and the coating layer at least comprises the target cation Q.

9. A lithium-ion battery, characterized in that, The lithium ion battery at least comprises the single-crystalline ternary cathode material according to claim 8.

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