Anode electrode materials, secondary batteries, and electrical devices.

Abstract

Invention details;

Description

Positive electrode material, secondary battery and electrical equipment

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on June 27, 2023, with application number 202310775504.X and titled “A positive electrode material, secondary battery and electrical equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery manufacturing technology, and in particular to a positive electrode material, a secondary battery and an electrical device. Background Art

[0003] Currently, sodium-ion batteries have received widespread attention due to the advantages of sodium layered oxide positive electrode materials, such as high theoretical capacity, abundant sodium resources, no internal crystalline water, and production methods compatible with lithium-ion batteries.

[0004] However, the interfacial impedance of the layered positive electrode materials of existing sodium ion batteries is large, and the battery's rate performance is poor. At the same time, the layered positive electrode materials are highly alkaline, and when slurried, the alkaline groups attack positive electrode binders such as polyvinylidene fluoride (PVDF), causing the slurry to gel and making processing difficult.

[0005] Summary of the Invention

[0006] The technical problem to be solved by the present application is to provide a positive electrode material, a secondary battery and an electrical device to solve the problem that the interface impedance of the positive electrode material of the existing sodium ion battery is large and it is easy to attack the positive electrode adhesive.

[0007] In order to solve the above problems, this application is implemented through the following technical solutions:

[0008] The present application proposes a positive electrode material, wherein the positive electrode material includes a core and a coating layer arranged on the surface of the core, the core includes a sodium ion layered oxide, and the coating layer includes a spinel-type lithium salt.

[0009] Furthermore, in the positive electrode material, the general structural formula of the spinel type lithium salt includes Li a Y2O4, wherein 0.8≤a≤1.1, and A is selected from at least one of Fe, Ni, Cu, Zn, Co, Ti, Mg, Al, Nb, Ta, and Mn.

[0010] Furthermore, in the positive electrode material, the spinel lithium salt includes LiNi 0.5 Mn 1.5 One or more of O4, LiMn2O4.

[0011] Furthermore, in the positive electrode material, the space group of the LiMn2O4 includes a mixed phase of Fd-3m and I41 / amd.

[0012] Furthermore, in the positive electrode material, the unit cell parameters of the Fd-3m phase LiMn2O4 satisfy a1=b1=c1, and the unit cell parameters of the I41 / amd phase LiMn2O4 satisfy a2=b2≠c2;

[0013] and / or

[0014] 40% <a2 / a1<60%,95%<c2 / c1<105%。

[0015] Furthermore, in the positive electrode material, 8 <a1=b1=c1<9,3.2<a2=b2<7.2,0.45<c2<9.45。

[0016] Furthermore, in the coating layer, the molar proportion of Fd-3m phase LiMn2O4 is 60 to 95%.

[0017] Furthermore, the pH value of the positive electrode material is 10.4 to 12.5.

[0018] Furthermore, the coating layer has a thickness of 50 to 500 nm.

[0019] Furthermore, the coating layer has a thickness of 100 to 300 μm.

[0020] Furthermore, the particle size Dv50 of the positive electrode material is 1 μm to 20 μm.

[0021] Furthermore, in the positive electrode material, the crystal structure of the sodium ion layered oxide includes P2 type and O3 type;

[0022] And / or the chemical formula of the sodium ion layered oxide is Na x MO2, wherein M is selected from at least one of Fe, Ni, Li, Cu, Zn, Co, Ti, and Mn, and 1>x>0.67.

[0023] The present application also proposes a secondary battery, comprising a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and the above-mentioned positive electrode material disposed on the positive electrode current collector.

[0024] The present application also proposes an electrical device, which includes the above-mentioned secondary battery, and the secondary battery serves as a power supply for the electrical device.

[0025] Compared with the prior art, the embodiments of the present application have the following advantages:

[0026] In an embodiment of the present application, the positive electrode material provided includes a core and a coating layer arranged on the surface of the core, the core includes a sodium ion layered oxide, and the coating layer includes a spinel-type lithium salt. Among them, the coating layer tightly coats the layered positive electrode material, which can reduce the contact interface between the layered positive electrode material and the electrolyte, alleviate the dissolution of metal ions, and improve the battery cycle performance; at the same time, the spinel-type lithium salt in the coating layer can provide a three-dimensional channel for sodium ion diffusion at the positive electrode material-electrolyte interface, increase the diffusion path, and increase the diffusion rate, thereby improving the battery cell rate performance; in addition, the spinel-type lithium salt has a low alkalinity, which not only reduces the attack on the positive electrode binder, but also allows lithium ions to escape from the positive electrode before sodium ions during the formation process and form a film on the negative electrode, generating a dense SEI film composed of lithium salts, thereby improving the cycle stability. Therefore, the positive electrode material provided in the embodiment of the present application solves the problem that the interface impedance of the positive electrode material of the existing sodium ion battery is large and easy to attack the positive electrode binder.

[0027] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] FIG1 is a schematic diagram of the structure of the positive electrode material provided in an embodiment of the present application.

[0030] Description of reference numerals:

[0031] 11- core, 12- cladding layer. Specific embodiments

[0032] The present application is described in detail below in conjunction with the described embodiments. Although specific embodiments of the present application are shown, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0033] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" are open-ended terms and should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present application, but the description is based on the general principles of the specification and is not intended to limit the scope of the present application. The scope of protection of this application shall be as defined by the attached claims.

[0034] The applicant of this application found that although sodium-ion batteries have a high theoretical capacity and rated voltage, the interfacial impedance of their layered oxide positive electrode materials is large, which affects the battery's rate performance and easily causes the dissolution of metal ions such as manganese at higher voltages, resulting in reduced battery cycle performance; at the same time, the layered positive electrode materials of sodium-ion batteries are highly alkaline, and the alkaline groups attack positive electrode binders such as polyvinylidene fluoride during homogenization, causing the slurry to gel and making processing difficult.

[0035] In order to solve the above problems, an embodiment of the present application provides a positive electrode material, as shown in Figure 1, the positive electrode material includes a core 11 and a coating layer 12 arranged on the surface of the core 11, the core 11 includes a sodium ion layered oxide, and the coating layer 12 includes a spinel-type lithium salt.

[0036] In the present application, the coating layer refers to a spinel-type lithium salt layer distributed on at least part of the surface of the sodium ion layered oxide particles, and the distribution area of ​​the spinel-type lithium salt layer accounts for more than 70% of the surface of the sodium ion layered oxide particles. Preferably, the spinel-type lithium salt layer is completely coated on the surface of the sodium ion layered oxide particles. Among them, the spinel-type lithium salt in the coating layer can provide a three-dimensional channel for the diffusion of sodium ions at the positive electrode material-electrolyte interface, increase the diffusion path, and can increase the diffusion rate, thereby improving the battery rate performance; at the same time, the spinel-type lithium salt has a low alkalinity, which can not only reduce the attack on the positive electrode adhesive, but also lithium ions can escape from the positive electrode before sodium ions during the formation process and form a film at the negative electrode, forming a dense SEI film composed of lithium salts, thereby improving the cycle stability. Therefore, the positive electrode material provided in the embodiment of the present application solves the problem that the interface impedance of the positive electrode material of the existing sodium ion battery is large and easy to attack the positive electrode adhesive. In addition, the coating layer tightly wraps the layered positive electrode material, which can reduce the contact interface between the layered positive electrode material and the electrolyte, improve the stability of the sodium ion layered oxide positive electrode material in the air, alleviate the dissolution of metal ions, and improve the battery cycle performance.

[0037] In practical applications, by performing TEM-SAED characterization on the positive electrode material provided in the embodiments of the present application, it is shown that its surface material has a crystal structure different from that of the internal layered oxide; at the same time, by using SEM EDS to characterize the surface material, the elemental composition and proportion of the spinel-type lithium salt can be determined, and combined with the crystal structure of the surface material characterized by TEM-SAED characterization, the presence of spinel-type lithium salt in the surface material can be determined.

[0038] In some embodiments, the pH value of the positive electrode material is 10.4 to 12.5. The positive electrode material coated with the coating layer can reduce the residual alkali on the surface of the positive electrode material, lower its pH value, and avoid excessive residual alkali content affecting the pulping process. Low surface residual alkali is beneficial to improving battery performance.

[0039] Optionally, in one embodiment, in the positive electrode material provided in the embodiment of the present application, the structural formula of the spinel lithium salt is Li a Y2O4, wherein 0.8≤a≤1.1, and Y is selected from at least one of Fe, Ni, Cu, Zn, Co, Ti, Mg, Al, Nb, Ta, and Mn.

[0040] The compound having the above structural formula can provide a three-dimensional channel for the diffusion of sodium ions at the positive electrode material-electrolyte interface. Since the diffusion path is increased, the diffusion rate of ions can be greatly improved, thereby improving the battery rate performance.

[0041] Alternatively, in one embodiment, the spinel lithium salt includes LiNi 0.5 Mn 1.5 O4 (lithium nickel manganate), LiMn2O4 (lithium manganate) or one or more, that is, the above-mentioned spinel lithium salt can be lithium nickel manganate, lithium manganate, etc., the spinel-shaped LiNi 0.5 Mn 1.5 O4 is an excellent high-voltage cathode material with an operating voltage of 4.7V. It offers high energy density (theoretical energy density reaches 695Wh / kg), high thermal and electrochemical stability (its structure remains intact even at high temperatures of 900°C), high safety, and excellent rate capability (its spinel structure has three-dimensional channels). It also features low raw material costs and a simple production process. Lithium manganese oxide with a spinel structure has advantages such as low-temperature resistance, good safety, and ease of preparation.

[0042] Optionally, in a specific embodiment, the above spinel-type lithium salt is LiMn2O4. Since lithium manganate itself does not react with carbon dioxide and water and has relatively weak alkalinity, using spinel-type lithium manganate to coat the sodium-ion layered oxide can effectively reduce the contact between the layered cathode material and carbon dioxide and water in the air, that is, it can reduce the generation of alkaline substances NaOH and Na2CO3, lower the alkalinity on the surface of the cathode material, not only improve the air stability of the sodium-ion battery layered cathode material, but also slow down the reaction between the layered cathode material and the cathode binder, and improve the processing performance.

[0043] Optionally, the space group of the above LiMn2O4 includes a mixed phase of Fd-3m and I41 / amd, and the mixed phase can form vacancy defects, which is more conducive to the insertion and extraction of sodium ions and improves the rate performance of the battery.

[0044] Optionally, in the embodiments of the present application, the lattice parameters of the Fd-3m phase LiMn2O4 satisfy 8 < a1 = b1 = c1 < 9, and the lattice parameters of the I41 / amd phase LiMn2O4 satisfy a2 = b2 ≠ c2; and / or 40% < a2 / a1 < 60%, 95% < c2 / c1 < 105%, 3.2 < a2 = b2 < 7.2, 0.45 < c2 < 9.45.

[0045] When the lattice parameters of the Fd-3m phase LiMn2O4 satisfy a1 = b1 = c1 and the lattice parameters of the I41 / amd phase LiMn2O4 satisfy a2 = b2 ≠ c2, or 40% < a2 / a1 < 60% and 95% < c2 / c1 < 105%, the coating layer can generate more voids, which is conducive to the insertion and extraction of sodium ions and improves the rate performance. When the lattice parameters of the Fd-3m phase and the I41 / amd phase LiMn2O4 simultaneously satisfy the above two conditions, the coating layer generates more voids, which is more conducive to the insertion and extraction of sodium ions, and the improvement effect on the rate performance is particularly good.

[0046] Optionally, in an embodiment, in the coating layer provided by the embodiments of the present application, the molar proportion of the Fd-3m phase LiMn2O4 is 60-95%, which can make the coating layer generate more hole numbers, is more conducive to the insertion and extraction of sodium ions, and further improves the rate performance of the battery.

[0047] Optionally, in an embodiment, the thickness of the above coating layer is 50-500 nm, for example, it is one of 50 μm, 100 μm, 200 μm, 300 μm, 400 μm or 500 μm or the range value of any two of them. In some embodiments, the thickness of the above coating layer is 100-300 μm. When the thickness of the coating layer is within the above range, it can take into account the energy density of the cathode material while reducing the alkalinity on the surface of the cathode material.

[0048] Optionally, in one embodiment, the particle size Dv50 of the positive electrode material is 1 μm to 20 μm. In some embodiments, the particle size Dv50 of the positive electrode material can be in the range of one or any two of 1 μm, 3 μm, 5 μm, 8 μm, 12 μm, 15 μm, 18 μm, and 20 μm. When the particle size Dv50 of the positive electrode material is within the above range, the positive electrode material has a suitable specific surface area and enables the battery electrode to have a suitable pore range, thereby reducing the occurrence of side reactions and improving the wettability of the electrode, thereby improving the cycle performance and rate performance of the battery.

[0049] In the actual preparation process, the Dv50 of the positive electrode material can be adjusted to 1-20 μm by changing the ball milling parameters. Specifically, the longer the ball milling time and the higher the rotation speed, the smaller the Dv50 of the obtained positive electrode material.

[0050] Alternatively, in one embodiment, the crystal structure of the sodium ion layered oxide includes P2 type and O3 type; and / or the chemical formula of the sodium ion layered oxide is Na x MO2, wherein M is selected from at least one of Fe, Ni, Li, Cu, Zn, Co, Ti, and Mn, and 1>x>0.67.

[0051] The cathode materials for sodium-ion batteries can be divided into P2 and O3 types due to their different crystal structures. P2-O3 mixed-phase cathode materials offer high rated voltages and excellent cycle stability. Using them as the core cathode material can help improve the battery's energy density and cycle life.

[0052] In the embodiment of the present application, a P2-type and O3-type mixed-phase sodium ion layered oxide is used as the core, and a spinel-type lithium salt is mixed and coated on its surface to form a coating layer. The spinel-type lithium salt is effectively utilized to provide a three-dimensional channel for sodium ion diffusion at the positive electrode material-electrolyte interface, thereby reducing the interfacial reaction impedance of the sodium ions and optimizing the rate performance of the battery. At the same time, the radius of the lithium ions in the coating layer is smaller than that of the sodium ions, and can escape from the positive electrode before the sodium ions during the formation process and form a film at the negative electrode to generate a dense SEI film composed of lithium salts, thereby improving the cycle stability. In addition, the coating layer is used to coat the P2-type and O3-type mixed-phase sodium ion layered oxide, which can reduce the contact interface between the sodium ion layered oxide and the electrolyte, alleviate the dissolution of metal ions, and thus improve the battery cycle performance. Moreover, because the spinel-type lithium salt has a low alkalinity, using it to coat the P2-type and O3-type mixed-phase sodium ion layered oxide can reduce the attack on the positive electrode adhesive, making it easier to process and form a positive electrode sheet.

[0053] In practical applications, the ratio of the P2 phase to the O3 phase can be adjusted by the sodium content x. When x is larger, the O3 phase accounts for a larger proportion, and when x is smaller, the P2 phase accounts for a larger proportion.

[0054] The present application also proposes a secondary battery comprising a positive electrode plate, wherein the positive electrode plate comprises a positive electrode current collector and the positive electrode material disposed on the positive electrode current collector. The secondary battery comprises a sodium ion secondary battery.

[0055] Optionally, in one embodiment, the positive electrode plate further includes an adhesive, and the adhesive may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylic resin.

[0056] In some embodiments, the positive electrode sheet is prepared as follows: the components for preparing the positive electrode sheet, such as the positive electrode material, the binder and any other components, are dispersed in a solvent such as N-methylpyrrolidone to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector; and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0057] The sodium ion battery provided in the embodiment of the present application further includes a negative electrode plate, a separator and an electrolyte.

[0058] Among them, the negative electrode plate includes a negative electrode current collector and a negative electrode active material layer arranged on the above-mentioned negative electrode current collector. The above-mentioned negative electrode active material layer can adopt negative electrode active materials for batteries known in the art, such as artificial graphite, natural graphite, hard carbon, soft carbon, carbon black, etc.

[0059] The electrolyte acts as a conductor of ions between the positive and negative electrodes, and can be liquid, gel, or solid. In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent, wherein the electrolyte salt is a sodium salt.

[0060] An embodiment of the present application further provides an electrical device, comprising the above-mentioned secondary battery, wherein the above-mentioned secondary battery is used to provide power.

[0061] For the above-mentioned secondary battery embodiments and electrical equipment embodiments, their positive electrode plates include a positive electrode active material layer, and the above-mentioned positive electrode active material layer includes the above-mentioned positive electrode material, and can achieve the same technical effects. To avoid repetition, they will not be described here. For relevant matters, please refer to the partial description of the positive electrode material embodiment.

[0062] In order to make the invention purpose, technical solution and beneficial effects of this application clearer, the present application is further described below in conjunction with examples. It should be understood that these examples are only used to illustrate this application and are not used to limit the scope of this application.

[0063] The present application is described in detail below through examples.

[0064] Performance testing methods

[0065] (1) pH value test of positive electrode material:

[0066] 5 g of positive electrode material was dissolved in 45 ml of ethanol solution, stirred at 200 r / min for 10 min, and then the pH value of the solution was tested using a pH tester.

[0067] (2) Environmental stability test:

[0068] After 10 g of the positive electrode material was placed in an environment at 25° C. and 50% water content for 7 days, the pH value was tested using the pH value test method as a test indicator of environmental stability.

[0069] (3) Discharge rate performance test:

[0070] At room temperature, the fully charged battery was discharged to 1.5V at a current density of 0.33C, and the capacity was recorded as C1.

[0071] Then, at room temperature, charge the battery to a full charge state (cut-off voltage of 3.8V) at a current density of 1C, and discharge the fully charged battery to 1.5V at a current density of 5C. The capacity is recorded as C2.

[0072] The capacity retention ratio C2 / C1 is calculated as a test indicator of discharge rate performance.

[0073] (4) Sodium ion diffusion coefficient test:

[0074] After the battery was filled to capacity, it was charged at a current density of 0.1C for 30 minutes, left for 2 hours, and then the above charging process was repeated until the voltage reached 4.0V; the constant current intermittent titration technique (GITT) was used to obtain the battery sodium ion diffusion coefficient.

[0075] (5) Cycling performance test: At room temperature, the battery was charged to 3.8 V at a current density of 1 C, and then discharged to 1.5 V at a current density of 1 C. The capacity C1 (initial capacity) during the first discharge cycle was recorded.

[0076] At room temperature, the battery was charged and discharged at a rate of 1C for a full charge-discharge cycle test with a voltage range of 1.5V to 3.8V. When the discharge capacity gradually decayed to 80%*C1, the test was stopped and the number of cycles was recorded.

[0077] Example 1

[0078] (1) Preparation of positive electrode materials:

[0079] a. At room temperature, a certain amount of Na2CO3, NiO, Fe2O3 and MnO2 were added to a ball mill at a molar ratio of n(Na):n(Ni):n(Fe):n(Mn)=1:1 / 3:1 / 3:1 / 3, and stirred at 300 rpm for 12 hours. The powder precursor was pressed into a sheet; the sheet precursor was then sintered in an air environment at 800°C for 12 hours. After cooling, the precursor was placed in a tube furnace and then sintered in an air environment at 800°C for 12 hours in a muffle furnace to obtain a sodium ion layered oxide NaNi with a P2-O3 mixed phase. 1 / 3 Fe 1 / 3 Mn 1 / 3 O2;

[0080] b. The sodium ion layered oxide is placed in a ball mill, and LiOH, Li2CO3, MnO2 and MnO are added, and the mass ratio of the added sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is controlled to be 20:0.33:0.33:1:1. Then, after stirring at 200 rpm for 12 hours, calcining at 1050°C for 12 hours, LiMn2O4 is reacted and coated on the surface of the sodium ion layered oxide. After crushing and sieving, a positive electrode material with a particle size Dv50 of 8 μm is obtained.

[0081] (2) Preparation of positive electrode sheet

[0082] The prepared positive electrode material was homogenized with PVDF and conductive carbon black in a mass ratio of 85:7.5:7.5 and evenly coated on one side of the positive electrode current collector. The electrode sheet surface density was controlled to be 15 mg / cm 2 After high-temperature drying, rolling, cutting and striping, the positive electrode sheet is prepared.

[0083] (3) Preparation of negative electrode sheet

[0084] The negative electrode materials hard carbon, styrene-butadiene rubber (SBR), conductive carbon black and sodium carboxymethyl cellulose (CMC) were homogenized in a mass ratio of 85:5.5:5.5:4 and evenly coated on one side of the negative electrode current collector. The coating density of the electrode sheet was controlled to be 8 mg / cm 2 After high-temperature drying, rolling, cutting and stripping, the negative electrode sheet is prepared.

[0085] (4) Preparation of sodium ion batteries

[0086] Using 20μm thick polypropylene (PP) as the separator, the positive electrode sheet, negative electrode sheet and separator are wound and placed in a shell, and then the electrolyte is injected and packaged (wherein the electrolyte is a solution of 1M NaClO4 dissolved in propylene carbonate (PC) solvent) to prepare a sodium ion battery.

[0087] Example 2

[0088] The difference between Example 2 and Example 1 is that in step (b), the calcination temperature is adjusted to 1300 degrees Celsius.

[0089] Example 3

[0090] The difference between Example 3 and Example 1 is that in step (b), the calcination temperature is adjusted to 1200 degrees Celsius.

[0091] Example 4

[0092] The difference between Example 4 and Example 1 is that in step (b), the calcination temperature is adjusted to 1100 degrees Celsius.

[0093] Example 5

[0094] The difference between Example 5 and Example 1 is that in step (b), the calcination temperature is adjusted to 900 degrees Celsius.

[0095] Example 6

[0096] The difference between Example 6 and Example 1 is that in step (b), the calcination temperature is adjusted to 800 degrees Celsius.

[0097] Example 7

[0098] The difference between Example 7 and Example 1 is that in step (a), the ball milling speed is adjusted to 300 rpm and the ball milling time is adjusted to 18 hours.

[0099] Example 8

[0100] The difference between Example 8 and Example 1 is that in step (a), the ball milling speed is adjusted to 100 rpm and the ball milling time is adjusted to 12 hours.

[0101] Example 9

[0102] The difference between Example 9 and Example 1 is that in step (a), the ball milling speed is adjusted to 400 rpm and the ball milling time is adjusted to 18 hours.

[0103] Example 10

[0104] The difference between Example 10 and Example 1 is that in step (a), the ball milling speed is adjusted to 100 rpm and the ball milling time is adjusted to 1 hour.

[0105] Example 11

[0106] The difference between Example 11 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 80:0.33:0.33:1:1.

[0107] Example 12

[0108] The difference between Example 12 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 200:0.33:0.33:1:1.

[0109] Example 13

[0110] The difference between Example 13 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 15:0.33:0.33:1:1.

[0111] Example 14

[0112] The difference between Example 14 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 10:0.33:0.33:1:1.

[0113] Example 15

[0114] The difference between Example 15 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 20:0.3:0.35:1:1.

[0115] Example 16

[0116] The difference between Example 16 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 20:0.4:0.3:1:1.

[0117] Example 17

[0118] The difference between Example 17 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 20:0.5:0.25:1:1.

[0119] Example 18

[0120] The difference between Example 18 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 20:0.33:0.33:0.8:1.2.

[0121] Example 19

[0122] The difference between Example 19 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 20:0.33:0.33:1.2:0.8.

[0123] Example 20

[0124] The difference between Example 20 and Example 1 is that in step (b), the mass ratio of sodium ion layered oxide, LiOH, Li2CO3, MnO2 and MnO is adjusted to 20:0.33:0.33:1.4:0.6.

[0125] Example 21

[0126] The difference between Example 21 and Example 1 is that in step (a), Na2CO3, NiO, Fe2O3 and MnO2 are added to the ball mill according to the molar ratio of n(Na):n(Ni):n(Fe):n(Mn) = 0.8:0.4:0.2:0.4.

[0127] Example 22

[0128] The difference between Example 22 and Example 1 is that in step (a), Na2CO3, NiO, Fe2O3 and MnO2 are added to the ball mill according to the molar ratio of n(Na):n(Ni):n(Fe):n(Mn)=0.6:0.4:0.2:0.4.

[0129] Example 23

[0130] The difference between Example 23 and Example 1 is that in step (a), Na2CO3, CuO, Fe2O3 and MnO2 are added to the ball mill according to the molar ratio of n(Na):n(Cu):n(Fe):n(Mn) = 0.6:0.4:0.2:0.4.

[0131] Example 24

[0132] The difference between Example 24 and Example 1 is that in step (a), Na2CO3, Co2O3 and MnO2 are added to the ball mill at a molar ratio of n(Na):n(Co):n(Mn)=0.6:0.2:0.8.

[0133] Example 25

[0134] The difference between Example 25 and Example 1 is that in step (b), the sodium ion layered oxide is placed in a ball mill, LiOH, Li2CO3, MnO2, MnO and NiO are added to the ball mill, and the mass ratio of the sodium ion layered oxide, LiOH, Li2CO3, MnO2, MnO and NiO is 20:0.33:0.33:0.75:0.75:0.5, and then after stirring at 200 rpm for 12 hours, calcining at 1050°C for 12 hours to react and generate LiNi 0.5 Mn 1.5 O4 and coated on the surface of sodium ion layered oxide.

[0135] Comparative Example 1

[0136] The difference between Comparative Example 1 and Example 1 is that, during the preparation of the positive electrode material, the sodium ion layered oxide is not coated, that is, step (b) is not included, and the prepared P2-O3 mixed phase sodium ion layered oxide is directly used to make the positive electrode sheet.

[0137] Comparative Example 2

[0138] The difference between Comparative Example 2 and Example 1 is that in step (b), Na2CO3, Co2O3 and MnO2 are added to the ball mill according to the molar ratio of n(Na):n(Co):n(Mn)=0.6:0.2:0.8.

[0139] The Fd-3m phase ratio, coating layer thickness, unit cell parameters a2 / a1, c2 / c1 in the coating layer, pH value, and particle Dv50 in each embodiment and comparative example were tested, and the test data are shown in Table 1.

[0140] The batteries prepared in each embodiment and comparative example were subjected to sodium ion conductivity test, discharge rate performance test, cycle performance test and environmental stability test. The test data are shown in Table 1.

[0141] Table 1

[0142] In summary, in this embodiment, the positive electrode material provided includes a core and a coating layer arranged on the surface of the core, the core includes a sodium ion layered oxide, and the coating layer includes a spinel-type lithium salt. Among them, the coating layer tightly coats the layered positive electrode material, which can reduce the contact interface between the layered positive electrode material and the electrolyte, alleviate the dissolution of metal ions, and improve the battery cycle performance; at the same time, the spinel-type lithium salt in the coating layer can provide a three-dimensional channel for the diffusion of sodium ions at the positive electrode material-electrolyte interface, increase the diffusion path, and can increase the diffusion rate, thereby improving the battery cell rate performance; in addition, the spinel-type lithium salt has a low alkalinity, which can not only reduce the attack on the positive electrode adhesive, but also the lithium ions can escape from the positive electrode before the sodium ions during the formation process and form a film at the negative electrode, generating a dense SEI film composed of lithium salts, thereby improving the cycle stability. Therefore, the positive electrode material provided in the embodiment of the present application solves the problem that the interface impedance of the positive electrode material of the existing sodium ion battery is large and easy to attack the positive electrode adhesive.

[0143] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic inventive concepts. Therefore, the claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0144] The above is a detailed introduction to a positive electrode material, a secondary battery and an electrical device provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0145] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application in any other manner. Any person skilled in the art may utilize the above disclosed technical content to modify or modify the present application into equivalent embodiments with equivalent variations. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present application and are based on the technical essence of the present application shall still fall within the scope of protection of the present application.

Claims

DEPCT6930 / 12 / 25681. Anode electrode material in which the anode electrode material consists of an inner core and a coating layer arranged on the surface of the inner core, the inner core consists of a sodium-ion oxide layer and the coating layer consists of a spinel lithium salt.

2. Anode electrode material according to claim 1 in which the general structural formula of the spinel lithium salt consists of LiaY2O4 in which 0.8 is less than or equal to a is less than or equal to 1.1 and Y is chosen from one or more of Fe, Ni, C.

1. Anode electrode material according to claim 1 where the spinel lithium salt consists of one or more LiNi0.5Mn1.5O4 and LiMn2O4.

2. Anode electrode material according to claim 3 where the LiMn2O4 space group consists of a mixed phase of Fd-3m and I41 / amd.

3. Anode electrode material according to claim 4 where the unit cell parameters of LiMn2O4 in the Fd-3m phase satisfy a1=b1=c1 and the unit cell parameters of LiMn2O4 in the I41 / amd phase satisfy a2=b2 not equal to c2 and / or 40%. <a2 / a1<ร้อยละ60และร้อยละ95<c2 / c1<ร้อยละ1056.Anode electrode material according to claim 5, where 8 <a1=b1=c1<9,3.2<a2=b2<7.2และ0.45<c2<9.457.วัสดุอิเล็กโทรดขั้วบวกตามข้อถือสิทธิที่5หรือ6ที่ซึ่งในชั้นเคลือบสัดส่วนโดยโมลของLiMn2O4ในเฟสFd-3mอยู่ที่ร้อยละ60~958.วัสดุอิเล็กโทรดขั้วบวกตามข้อถือสิทธิที่1ที่ซึ่งค่าpHของวัสดุอิเล็กโทรดขั้วบวกอยู่ที่10.4~12.59.วัสดุอิเล็กโทรดขั้วบวกตามข้อถือสิทธิที่1ที่ซึ่งความหนาของชั้นเคลือบอยู่ที่50~500นาโนเมตร10.วัสดุอิเล็กโทรดขั้วบวกตามข้อถือสิทธิที่1ที่ซึ่งความหนาของชั้นเคลือบอยู่ที่100~300ไมโครเมตร11.วัสดุอิเล็กโทรดขั้วบวกตามข้อถือสิทธิที่1ที่ซึ่งขนาดอนุภาคDv50ของวัสดุอิเล็กโทรดขั้วบวกอยู่ที่1ไมโครเมตร~20ไมโครเมตร12.วัสดุอิเล็กโทรดขั้วบวกตามข้อถือสิทธิที่1ที่ซึ่งโครงสร้างผลึกของออกไซด์ที่เป็นชั้นของโซเดียม-ไอออนประกอบรวมด้วยแบบP2และแบบO313.วัสดุอิเล็กโทรดขั้วบวกตามข้อถือสิทธิที่1ที่ซึ่งสูตรเคมีของออกไซด์ที่เป็นชั้นของโซเดียม-ไอออนคือNaxMO2ที่ซึ่งMถูกเลือกจากอย่างน้อยหนึ่งตัวของFe,Ni,Li,Cu,Zn,Co,TiและMnและ1> x>0.6714.A secondary battery consisting of an anode electrode plate in which the anode electrode plate is incorporated with an anode current receiver and anode electrode material as specified in any of Claims 1 through 13, which is arranged on the anode current receiver.

15. An electrical device in which the electrical device consists of a secondary battery as specified in Claim 14, and the secondary battery serves as a power source for the electrical device.

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