Positive electrode material, manufacturing method for the same, and application thereof

Abstract

To provide a positive electrode material, a manufacturing method for the same, and an application thereof, capable of improving the interface stability between a positive electrode sheet and a solid electrolyte and enhancing the stability and cycle performance of a lithium ion battery.SOLUTION: The present invention provides a positive electrode material, a manufacturing method for the same, and an application thereof. The positive electrode material includes at least a positive electrode active material, and a coating layer coating the positive electrode active material and containing a halide solid electrolyte. The positive electrode active material includes nLi2MnO3 / (1-n)LiMnaCobNicO2, in which 0.2≤n≤0.5 and a+b+c=1 are satisfied. The chemical formula of the halide solid electrolyte is Li2+mZr1-mFemCl6-x-yBrxIy, in which 0<m≤0.5, x=0 to 6, y=0 to 6, and x+y≤6 are satisfied.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion batteries, and particularly to a positive electrode material, a manufacturing method thereof, and an application thereof.

Background Art

[0002] With the development of secondary batteries centered around lithium-ion batteries, lithium-ion batteries are widely used in portable electronic products, electric vehicles, and the like. However, in recent years, due to the use of flammable organic solvents as electrolytes in conventional lithium-ion batteries, safety accidents have occurred frequently, posing a significant risk to safety. This problem cannot be completely solved by conventional improvement methods. In contrast, all-solid-state lithium-ion batteries using inorganic solid electrolytes are safer. Among existing inorganic solid electrolytes, sulfide solid electrolytes as electrolytes are expected to be applied due to advantages such as high lithium-ion conductivity, low interfacial resistance, and Young's modulus. However, since the interface between the positive electrode material for high voltage and the sulfide solid electrolyte is stable, the cycle performance of the positive electrode deteriorates. This problem can be alleviated by modifying the surface of the high-voltage lithium-excess manganese-based positive electrode material with a stable oxide coating layer, but this requires special equipment and high costs.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The present invention provides a positive electrode material, a manufacturing method thereof, and an application thereof. By the positive electrode material, the manufacturing method thereof, and the application provided by the present invention, the cost can be significantly reduced, side reactions between the positive electrode material and the sulfide electrolyte under high voltage can be effectively suppressed, the interfacial stability between the electrode and the solid electrolyte can be improved, and thereby the stability and cycle performance of the battery can be improved.

Means for Solving the Problems

[0004] In order to solve the above technical problems, the present invention is realized through the following technical solutions.

[0005] The present invention provides a positive electrode material including at least the following. A positive electrode active material, and A coating layer that coats the positive electrode active material and contains a halide solid electrolyte. Here, the positive electrode active material is nLi 2 MnO 3 ·(1-n)LiMn a Co b Ni c O 2 and 0.2 ≦ n ≦ 0.5, a + b + c = 1. The chemical formula of the halide solid electrolyte is Li 2+m Zr 1-m Fe m Cl 6-x-y Br x I y where 0 < m ≦ 0.5, x = 0 to 6, y = 0 to 6, and x + y ≦ 6.

[0006] In one embodiment of the present invention, the molar ratio of iron atoms on the surface of the positive electrode material measured by an energy dispersive X-ray analyzer is 0.4% to 7%.

[0007] In one embodiment of the present invention, the chemical formula of the halide solid electrolyte is Li 2.3 Zr 0.7 Fe 0.3 Cl 6 is.

[0008] In one embodiment of the present invention, the positive electrode active material is spherical.

[0009] In one embodiment of the present invention, the median diameter D50 of the spherical positive electrode active material is 8 μm to 20 μm.

[0010] The present invention also provides a method for manufacturing a positive electrode material including at least the following steps. Mixing compounds containing Li, Zr, and Fe elements in corresponding amounts, performing polishing and primary sintering to obtain a halide solid electrolyte according to the chemical formula of the halide solid electrolyte, and The halide solid electrolyte and the cathode active material are mixed according to the mass ratio and secondarily fired to obtain a cathode material.

[0011] In one embodiment of the present invention, the mass ratio of the halide solid electrolyte to the cathode active material is (0.2 to 6):(99.9 to 94).

[0012] In one embodiment of the present invention, the mixing conditions include a mixing speed of 100 rpm to 800 rpm and a mixing time of 1 hour to 6 hours.

[0013] In one embodiment of the present invention, the temperature of the secondary firing is 950°C to 1050°C, and the sintering time is 6 hours to 18 hours.

[0014] Further, the present invention provides a lithium-ion battery including the above cathode material or the cathode material obtained by the above manufacturing method.

[0015] Further, the present invention provides an electronic device including the above lithium-ion battery.

Advantages of the Invention

[0016] Based on the above, the present invention provides a cathode material, a manufacturing method, and an application thereof for obtaining a halide solid electrolyte having low cost, high ionic conductivity, and high breakdown voltage resistance, thereby solving the problem of instability at the interface between a high-voltage lithium-excess manganese-based cathode material and a sulfide solid electrolyte. The halide solid electrolyte has high compatibility with the high-voltage lithium-excess manganese-based cathode material, improves the lithium-ion conductivity of the cathode material, effectively improves the ion transfer dynamics of the cathode material, and thereby can improve the rate performance of the battery. Thereby, side reactions between the cathode material and the sulfide electrolyte under high voltage can be effectively suppressed, the interface stability between the electrode and the solid electrolyte can be improved, and thereby the stability and cycle performance of the battery can be improved. By improving the reversible oxidation-reduction ability of oxygen during cycling, dissolution of transition metals and release of oxygen from the cathode can be suppressed, and the initial Coulomb efficiency and cycle life can be improved.

Brief Description of the Drawings

[0017] To more clearly explain the technical solutions in the embodiments of the present invention, the figures necessary for the description of the embodiments are briefly introduced below. Obviously, the figures in the following description are only a part of the embodiments of the present invention, and those skilled in the art can obtain other figures based on these figures without the need for creativity.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0018] Hereinafter, the embodiments of the present invention will be described through specific examples. However, those skilled in the art can easily understand other advantages and effects of the present invention from the disclosure of this specification. The present invention may be implemented or applied through other different specific embodiments, and various modifications or changes can be made to the details of this specification based on different viewpoints and applications without departing from the spirit of the present invention.

[0019] It should be understood that the present invention can be embodied in different forms and should not be construed as being limited to the examples described in this specification. Rather, these examples are provided so that this disclosure is thorough and complete and conveys the scope of the present invention fully to those skilled in the art. In addition, in the following examples, "%" and "parts" mean "mass %" and "parts by mass" respectively, unless otherwise specified.

[0020] The technical solution of the present invention will be further described in detail below with reference to several embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on one embodiment of the present invention, all other embodiments can be obtained by those skilled in the art without creative efforts and are included within the scope of the present invention.

[0021] The present invention provides a positive electrode material including a positive electrode active material and a coating layer covering the positive electrode active material. Here, the positive electrode active material is a high-voltage positive electrode active material, and the high-voltage positive electrode active material is, for example, a lithium-excess manganese-based positive electrode material. Further, nLi 2 MnO 3 ·(1 - n)LiMn a Co b Ni c O 2 is included, where 0.2 ≤ n ≤ 0.5 and a + b + c = 1. The coating layer includes a halide solid electrolyte, and the chemical formula of the halide solid electrolyte is, for example, Li 2+m Zr 1-m Fe m Cl 6-x-y Br x I y where 0 < m ≤ 0.5, x = 0 to 6, y = 0 to 6, and x + y ≤ 6. In one embodiment of the present invention, the halide solid electrolyte is, for example, Li 2.3 Zr 0.7 Fe 0.3 Cl 6 In the present invention, the halide solid electrolyte does not contain rare earth metals. Therefore, the cost can be significantly reduced. The halide solid electrolyte uses iron as a doping element, thereby further reducing the cost. Fe in the crystal lattice 3+By substitution, the ionic conductivity of the halide solid electrolyte can be improved. Since the Fe element has a stronger binding ability with the O element in the lithium-excess manganese-based cathode material, it is beneficial for improving the reversible redox ability of the O element during cycling, thereby suppressing the dissolution of transition metals and the release of oxygen from the cathode, and improving the initial Coulombic efficiency and cycle life. The halide solid electrolyte is coated on the high-voltage lithium-excess manganese-based cathode material, effectively suppressing the side reaction between the cathode active material and the sulfide electrolyte under high voltage, improving the interfacial stability between the electrode and the solid electrolyte, and thereby improving the stability and cycle performance of the battery.

[0022] In one embodiment of the present invention, the cathode active material is, for example, spherical, and the median diameter D50 of the cathode active material in the spherical shape is 8 μm to 20 μm. The median diameter of the cathode active material is controlled to prevent the deterioration of processability due to too small particle size and the deterioration of electrochemical performance due to too large particle size, and at the same time, to improve the processing performance and electrochemical performance of the cathode active material.

[0023] In one embodiment of the present invention, in the cathode material, the halide solid electrolyte is uniformly coated on the surface of the cathode active material. The distribution of iron atoms on the surface of the cathode material is measured by an energy-dispersive X-ray analyzer (EDS) to judge the coating amount and coating uniformity of the halide solid electrolyte. In this embodiment, the molar ratio of iron atoms on the surface of the cathode material is, for example, 0.4% to 7%. That is, the halide solid electrolyte has good compatibility with the high-voltage lithium-excess manganese-based cathode material nLi 2 MnO 3 ·(1-n)LiMn a Co b Ni c O 2 and. At the same time, by coating the surface of the cathode active material with a halide solid electrolyte having high ionic conductivity, the ion transport dynamics can be effectively improved, thereby improving the rate performance of the battery.

[0024] Referring to FIG. 1, the present invention also provides a method for manufacturing a positive electrode active material. The manufacturing method includes, but is not limited to, steps S100 to S200.

[0025] Step S100: According to the chemical formula of the halide solid electrolyte, compounds containing Li, Zr, and Fe are mixed in corresponding amounts, ground, and sintered once to obtain a halide solid electrolyte.

[0026] Step S200: The halide solid electrolyte and the positive electrode active material are mixed according to the mass ratio and sintered a second time to obtain a positive electrode material.

[0027] Referring to FIG. 1. In one embodiment of the present invention, in step S100, for the chemical formula of the halide solid electrolyte Li 2+a Zr 1-a Fe a Cl (6-x-y) Br x I y according to the chemical formula, compounds containing corresponding molar amounts of Li, Zr, and Fe ions are mixed to form a mixture, and then this mixture is ground and sintered once to obtain a halide solid electrolyte. In one embodiment of the present invention, the chemical formula of the halide solid electrolyte is, for example, Li 2.3 Zr 0.7 Fe 0.3 Cl 6 and as raw materials, for example, lithium chloride (LiCl), zirconium chloride (ZrCl 4 ), ferric chloride (FeCl 3 ) etc. are selected. In this embodiment, in order to mix and contact the raw materials more uniformly, for example, various raw materials are mixed by a ball mill. The rotation speed of the ball mill is, for example, 400 rpm to 700 rpm, or 500 rpm. The mixing time of the ball mill is, for example, 1.5 hours to 3 hours, or 2 hours. The diameter of the zirconium beads treated by the ball mill is, for example, 8 mm to 15 mm, or 10 mm. The ratio of balls to materials is, for example, (20:30):1, or 30:1.

[0028] Refer to FIG. 1. In one embodiment of the present invention, in step S100, after obtaining the mixture, the mixture can be processed by, for example, a ball mill, solid-phase sintering, a heat eutectic method, etc., or the mixture can be prepared by polishing and sintering. Here, the polishing speed is, for example, 900 rpm, 1200 rpm, or 1000 rpm. The rotation speed is 8 to 15 hours, or 10 hours. The polishing time is, for example, 8 hours to 15 hours, or 10 hours. The polished mixture is subjected to a primary sintering treatment to obtain a halide solid electrolyte. Specifically, the heating rate of sintering is, for example, 4 °C / min to 5 °C / min, the temperature of the primary sintering is, for example, 250 °C to 350 °C, the sintering time is 3 hours to 5 hours, the sintering atmosphere is, for example, an inert gas, and the sintering time is the time after heating to the temperature of the primary sintering. Through the primary sintering, the crystallinity of the halide solid electrolyte can be enhanced. After the sintering is completed, the halide solid electrolyte is cooled by furnace cooling. In the halide solid electrolyte of the present invention, Fe element is used as a doping element, and the equivalent substitution of Fe 3+ in the crystal lattice improves the ionic conductivity of the electrolyte. In one embodiment of the present invention, the ionic conductivity of the halide solid electrolyte is ≧ 1 mS / cm.

[0029] Refer to FIG. 1. In one embodiment of the present invention, in step S200, after obtaining the halide solid electrolyte, the halide solid electrolyte and the cathode active material are blended according to the mass ratio. In this embodiment, the mass ratio of the halide solid electrolyte to the cathode active material is (0.2 to 6):(99.99 to 94), for example, 0.8:99.8, 1:99, 2:98, 3:97, 4:96, or 5:95, etc. In the mixing process, the rotation speed of the mixer is, for example, 100 rpm to 800 rpm, the mixing time is, for example, 1 hour to 6 hours, and the ball-to-material ratio is, for example, 20:1. Next, secondary firing is performed on the mixed halide solid electrolyte and cathode active material. Here, the heating rate of sintering is, for example, 8 °C / min to 10 °C / min, the temperature of secondary firing is, for example, 950 °C to 1050 °C, the sintering time is, for example, 6 hours to 18 hours, the sintering atmosphere is, for example, an inert gas, and the sintering time is the time after heating up to the temperature of secondary firing. In this embodiment, the cathode active material is, for example, nLi 2 MnO 3 ·(1 - n)LiMn a Co b Ni c O 2 etc., 0.2 ≤ n ≤ 0.5, a + b + c = 1, and the cathode active material is spherical. When the obtained cathode material was tested by energy-dispersive X-ray spectroscopy, the molar ratio of Fe atoms on the surface was 0.4% to 7%. Secondary firing helps the halide solid electrolyte and the lithium-excess manganese-based cathode material to form a good ion-permeable interface, improve the density of the halide solid electrolyte, and obtain a high-quality cathode material.

[0030] The present invention also provides a lithium-ion battery including a positive electrode sheet, a solid electrolyte, and a negative electrode sheet. Here, the solid electrolyte is disposed between the positive electrode sheet and the negative electrode sheet. Here, the solid electrolyte is obtained, for example, by pressing a fast ion conductor into a tablet, and the pressure is maintained for 3 to 8 minutes under a pressure of 0.8 to 1.5 tons. In other embodiments, other preparation methods can also be used to obtain the solid electrolyte. In this embodiment, examples of the fast ion conductor include sulfide fast ion conductors, and the sulfide fast ion conductor is, for example, Li 6 PS 5 Cl. The positive electrode sheet includes a positive electrode material, a fast ion conductor, a conductive agent, and the like. Here, the positive electrode material is a positive electrode material coated with a halide solid electrolyte, and the fast ion conductor may be the same as or different from the fast ion conductor in the solid electrolyte, for example. In this embodiment, the fast ion conductor in the positive electrode sheet is, for example, Li 6 PS 5 Cl, etc., and the conductive agent is, for example, conductive carbon black (Super P, SP), carbon nanotube (CNT), carbon fiber (VGCF), graphene, silver powder, aluminum powder, etc. In one embodiment of the present invention, the mass ratio of the positive electrode material, the fast ion conductor, and the conductive agent is, for example, (65 to 89):(10 to 30):(1 to 5). The positive electrode material, the fast ion conductor, and the conductive agent are ground in a mortar for 15 to 30 minutes and uniformly mixed to obtain a composite positive electrode powder. This composite positive electrode powder is pressed onto the solid electrolyte and held for 3 to 8 minutes under a pressure of 0.8 to 1.5 tons to obtain a positive electrode sheet. The negative electrode sheet is, for example, a metallic lithium sheet. By pressing this metallic lithium sheet from the solid electrolyte side opposite to the positive electrode sheet and holding it, for example, under a pressure of 0.1 to 0.2 tons, an all-solid-state lithium-ion battery is obtained. Here, the assembly process of the all-solid-state lithium-ion battery is completed in a glove box under an argon atmosphere.

[0031] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples. Appropriate modifications can be made without departing from the gist of the present invention, and all of them also belong to the technical scope of the present invention.

[0032] Example 1

[0033] Li 2.3 Zr 0.7 Fe 0.3 Cl 6 and 0.5Li 2 MnO 3 ·0.5LiMn 1 / 3 Co 1 / 3 Ni 1 / 3 O 2 were put into a ball mill and mixed according to a mass ratio of 3:97. Here, the mixing speed was 600 rpm, the mixing time was 3 hours, and the ball milling ratio was 20:1. Then, the mixed powder was put into a muffle furnace and sintered with a heating rate of 10 °C / min, a sintering temperature of 1000 °C, a sintering time of 12 hours, and an argon passing atmosphere. After sintering, it was polished and sieved to obtain a high-voltage lithium-excess manganese-based cathode material coated with a halide solid electrolyte. According to the energy-dispersive X-ray spectroscopy test, the molar ratio of Fe atoms on the surface of the cathode material was 2.8%.

[0034] Li 6 PS 5 50 mg of Cl was taken out, put into a mold, held under a pressure of 1 ton for 5 minutes, and pressed into the solid electrolyte. The coated cathode material, Li 6 PS 5 Cl, and the conductive agent conductive carbon black were weighed in a mass ratio of 70:29:1 in sequence, added to a mortar, and ground by hand for 20 minutes to obtain a composite cathode powder. Next, 10 mg of the composite cathode powder was placed on the solid electrolyte and held under a pressure of 1 ton for 5 minutes to form a cathode sheet. After removal, the solid electrolyte was turned over, and a lithium metal piece was placed on the solid electrolyte side with respect to the cathode sheet. The diameter of the lithium metal piece was 10 mm. This was pressurized to 0.1 ton and the pressure was maintained to obtain an all-solid-state lithium-ion battery. Here, the assembly process of the all-solid-state lithium-ion battery was completed in a glove box under an argon atmosphere.

[0035] Example 2

[0036] Li 2.3 Zr 0.7 Fe 0.3 Cl 6 and 0.5Li 2 MnO 3 ·0.5LiMn 1 / 3 Co 1 / 3 Ni 1 / 3 O 2 had a mass ratio of 6:94. The molar ratio of Fe atoms on the surface of the cathode material was 6.8%. Other operations were the same as in Example 1.

[0037] Example 3

[0038] Li 2.3 Zr 0.7 Fe 0.3 Cl 6 and 0.5Li 2 MnO 3 ·0.5LiMn 1 / 3 Co 1 / 3 Ni 1 / 3 O 2 had a mass ratio of 0.2:99.8. The molar ratio of Fe atoms on the surface of the cathode material was 0.5%. Other operations were the same as in Example 1.

[0039] Comparative Example 1

[0040] Li 6 PS 5 50 mg of Cl was taken out, placed in a mold, held under a pressure of 1 ton for 5 minutes, and pressed into the solid electrolyte. Uncoated 0.5Li 2 MnO 3 ·0.5LiMn 1 / 3 Co 1 / 3 Ni 1 / 3 O 2 , Li 6 PS 5Cl, conductive agent, conductive carbon black were weighed in a mass ratio of 70:29:1 in sequence, added to a mortar, and ground by hand for 20 minutes to obtain composite cathode powder. Next, 10 mg of the composite cathode powder was placed on the solid electrolyte and held under a pressure of 1 ton for 5 minutes to form a cathode sheet. After removal, the solid electrolyte was turned over, and a lithium metal piece was placed on the solid electrolyte side with respect to the cathode sheet. The diameter of the lithium metal piece was 10 mm. This was pressurized to 0.1 ton and the pressure was maintained to obtain an all-solid-state lithium-ion battery. Here, the assembly process of the all-solid-state lithium-ion battery was completed in a glove box under an argon atmosphere.

[0041] Comparative Example 2

[0042] Li 2.3 Zr 0.7 Fe 0.3 Cl 6 and 0.5Li 2 MnO 3 ·0.5LiMn 1 / 3 Co 1 / 3 Ni 1 / 3 O 2 The mass ratio was 0.05:99.95. The molar ratio of Fe atoms on the surface of the cathode material was 0.1%, and other operations were the same as in Example 1.

[0043] Comparative Example 3

[0044] Li 2.3 Zr 0.7 Fe 0.3 Cl 6 and 0.5Li 2 MnO 3 ·0.5LiMn 1 / 3 Co 1 / 3 Ni 1 / 3 O 2 The mass ratio was 15:85. The molar ratio of Fe atoms on the surface of the cathode material was 10%. Other operations were the same as in Example 1.

[0045] In Examples 1 to 3 and Comparative Examples 1 to 3 of the present invention, lithium-ion batteries were fabricated using different positive electrode materials. In an environment of 25 °C, an electrochemical workstation manufactured by Wuhan Land Electronics Co., Ltd. was used. According to the standard test methods for the gram capacity and initial Coulomb efficiency of the obtained all-solid-state lithium-ion batteries, tests were conducted at a voltage range of 2.0 V to 4.8 V and a test rate of 0.1C. The performance test results of the lithium-ion batteries of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1.

[0046]

Table 1

[0047] Refer to FIGS. 2 to 5. The scanning electron microscope (SEM) images and EDS energy spectra of the coated positive electrode material manufactured in Example 1 are shown in FIGS. 2 and 3. As can be seen from FIGS. 2 and 3, a layer of a coating material containing Fe element appears on the surface after the application of the halide solid electrolyte, and no damage is observed on the surface. The EDS energy spectra of the untreated positive electrode active material of Comparative Example 1 are shown in FIGS. 4 and 5. As can be seen from FIGS. 4 and 5, the particle surface of the uncoated lithium-excess manganese-based positive electrode material is smooth and does not contain Fe element. Therefore, in the present invention, the halide solid electrolyte can be uniformly coated on the particles of the lithium-excess manganese-based positive electrode material without affecting the morphology of the particles of the lithium-excess manganese-based positive electrode material.

[0048] Refer to Table 1. Comparing Examples 1 to 3 with Comparative Example 1, by coating the halide solid electrolyte, the gram capacity of the lithium-ion battery could be increased and the Coulombic efficiency could be improved. That is, the halide solid electrolyte has high compatibility with the high-voltage lithium-excess manganese-based cathode material, can effectively improve the ion transfer dynamics of the cathode material, and thereby improve the rate performance of the battery. The halide solid electrolyte can coat the high-voltage lithium-excess manganese-based cathode material to effectively suppress the side reaction between the cathode material and the sulfide electrolyte under high voltage, and improve the interfacial stability between the cathode and the solid electrolyte, thereby improving the stability and cycle performance of the lithium-ion battery.

[0049] Refer to Table 1. Comparing Examples 1 to 3 with Comparative Examples 2 to 3, when the molar ratio of Fe atoms on the surface of the cathode material was increased or decreased, the coating amount of the halide solid electrolyte also changed simultaneously. When the coating amount was too small, the small coating layer could not suppress the side reaction between the high-voltage cathode active material and the sulfide electrolyte, resulting in low initial Coulombic efficiency and cathode gram capacity. When the coating amount was too large, the halide solid electrolyte coating layer with low electron conductivity affected the electron contact of the cathode active material and affected the gram capacity. Therefore, by controlling the coating amount of the halide solid electrolyte on the surface of the cathode active material, the capacity and cycle characteristics of the lithium-ion battery can be improved simultaneously.

[0050] The present invention also provides an electronic device. The electronic device includes at least one lithium-ion battery, and the lithium-ion battery is used to supply electrical energy. In particular, the electronic device may be a vehicle, a mobile phone, a portable device, a laptop, a ship, a spacecraft, an electric toy, an electric tool, etc. In one embodiment of the present invention, the vehicle is, for example, a new energy vehicle. The new energy vehicle may be a pure electric vehicle, a hybrid vehicle, a range extender vehicle, etc. The spacecraft includes aircraft, rockets, space shuttles, spacecraft, etc. The electric toys include stationary or mobile electric toys such as game consoles, electric toy cars, electric toy boats, and electric airplanes. The electric tools include electric tools for metal cutting, electric tools for grinding, electric tools for assembly, and electric tools for railways. Examples include electric drills, electric grinders, electric wrenches, electric drivers, electric hammers, impact drills, concrete vibrators, electric cutters, etc. Since the electronic device is equipped with a lithium-ion battery, the advantages of the lithium-ion battery are also included here, but will not be described in detail.

[0051] Based on the above, the present invention provides a positive electrode material, a manufacturing method, and its applications. By coating the positive electrode active material with a halide solid electrolyte and doping the halide solid electrolyte with iron element, a halide solid electrolyte with low cost, high ionic conductivity, and high breakdown voltage can be obtained, thereby solving the problem of interface instability between the high-voltage lithium-excess manganese-based positive electrode material and the sulfide solid electrolyte. The halide solid electrolyte has high compatibility with the high-voltage lithium-excess manganese-based positive electrode material, improves the lithium ion conductivity of the positive electrode material, effectively improves the ion transfer dynamics, and thereby can improve the rate performance of the battery. Thereby, the side reaction between the positive electrode material and the sulfide electrolyte under high voltage can be effectively suppressed, the interface stability between the electrode and the solid electrolyte can be improved, and thereby the stability and cycle performance of the battery can be improved. The Fe element in the halide solid electrolyte has a stronger binding ability with the O element in the lithium-excess manganese-based positive electrode material, so it is beneficial to improve the reversible oxidation-reduction ability of oxygen during cycling, thereby suppressing the dissolution of transition metals and the release of oxygen from the positive electrode, and improving the initial Coulomb efficiency and cycle life.

[0052] The above description is only a preferred embodiment of the present application and only an explanation of the technical principle used. Those skilled in the art should understand that the scope of the invention according to the present application is not limited to the technical solution formed by the specific combination of the above technical features, and at the same time, other technical solutions formed by any combination of these technical features should also be included. Without departing from the concept of the present invention, technical solutions (but not limited thereto) formed by replacing the above technical features or their equivalent features, for example, replacing the above features with technical features having the same functions disclosed in the present application, are included.

[0053] Except for the technical features described in this specification, the remaining technical features are known to those skilled in the art. In order to emphasize the innovative features of the present invention, the remaining technical features are not described in detail here.

Industrial Applicability

[0054] The positive electrode material and manufacturing method provided by the present invention can be applied to lithium-ion batteries.

Explanation of symbols

[0055] S100, S200: Steps

Claims

1. a positive electrode active material, a coating layer that covers the positive electrode active material and contains a halide solid electrolyte, and at least includes, The positive electrode active material is nLi ２ MnO ３ ·(1 - n)LiMn ａ Co ｂ Ni ｃ O ２ and 0.2 ≤ n ≤ 0.5, a + b + c = 1. The chemical formula of the halide solid electrolyte is Li ２＋ｍ Zr １－ｍ Fe ｍ Cl ６－ｘ－ｙ Br ｘ I ｙ where 0 < m ≤ 0.5, x = 0 to 6, y = 0 to 6, and x + y ≤ 6, a positive electrode material.

2. The molar ratio of iron atoms on the surface of the positive electrode material measured by an energy dispersive X-ray analyzer is 0.4% to 7%. The positive electrode material according to Claim 1.

3. The chemical formula of the halide solid electrolyte is Li ２．３ Zr ０．７ Fe ０．３ Cl ６ The positive electrode material according to claim 1, which is as described above.

4. The positive electrode active material is spherical. The positive electrode material according to Claim 1.

5. The median diameter D50 of the spherical positive electrode active material is 8 μm to 20 μm. The positive electrode material according to Claim 4.

6. Mixing compounds containing Li, Zr, and Fe elements in corresponding amounts, performing polishing and primary sintering to obtain a halide solid electrolyte according to the chemical formula of the halide solid electrolyte, mixing the halide solid electrolyte and the positive electrode active material according to the mass ratio, and performing secondary sintering to obtain a positive electrode material, and at least includes, a method for manufacturing a positive electrode material.

7. The mass ratio of the halide solid electrolyte to the positive electrode active material is (0.2 to 6):(99.9 to 94). The method for manufacturing a positive electrode material according to Claim 6.

8. The conditions for the mixing include a mixing speed of 100 rpm to 800 rpm and a mixing time of 1 hour to 6 hours. The method for manufacturing a positive electrode material according to Claim 6.

9. The temperature of the secondary sintering is 950°C to 1050°C, and the sintering time is 6 hours to 18 hours. The method for manufacturing a positive electrode material according to Claim 6.

10. A lithium-ion battery including the positive electrode material according to Claim 1.

11. An electronic device including the positive electrode material according to Claim 1.

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