CN117334892A - Manganese-based layered high-entropy oxide positive electrode material and preparation method thereof - Google Patents

Manganese-based layered high-entropy oxide positive electrode material and preparation method thereof Download PDF

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CN117334892A
CN117334892A CN202311150699.5A CN202311150699A CN117334892A CN 117334892 A CN117334892 A CN 117334892A CN 202311150699 A CN202311150699 A CN 202311150699A CN 117334892 A CN117334892 A CN 117334892A
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positive electrode
kmo
manganese
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electrode material
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郭少华
褚世勇
邵曹阳
韩东
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Nanjing Research Institute Of Nanjing University
Nanjing University
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Nanjing University
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Abstract

The invention relates to the technical field of potassium ion battery materials, in particular to a manganese-based layered high-entropy oxide positive electrode material and a preparation method thereof. The invention realizes high entropy strategy modification through a solid phase sintering process, synthesizes a P3-phase manganese-based layered high entropy oxide positive electrode material HE-KMO and discloses a preparation method thereof. The material has more flexible bulk phase and surface structure through high entropy strategy modification, so that the capacity retention rate and the rate capability of the potassium ion battery in the charge-discharge cycle process are improved, and the electrochemical performance is improved; the HE-KMO is a P3 pure-phase material, can inhibit generation of orthorhombic system impurity phases, has excellent structural stability, and improves cycle performance and rate performance; meanwhile, the HE-KMO can effectively reduce the charge transfer resistance of the electrode material in the charge-discharge process, and improve the circulation stability of the electrode material.

Description

Manganese-based layered high-entropy oxide positive electrode material and preparation method thereof
Technical Field
The invention relates to the technical field of potassium ion battery materials, in particular to a manganese-based layered high-entropy oxide positive electrode material and a preparation method thereof.
Background
In recent years, the importance of environmental protection and sustainable development is gradually realized, and renewable energy sources such as wind energy, solar energy and the like are unprecedented to be developed and utilized. Secondary batteries are often used as an excellent energy storage device in combination with these intermittent renewable energy sources to achieve efficient use of energy, and thus the demand for secondary batteries is increasing. The current mature lithium ion battery technology is well suited for large scale energy storage systems in terms of performance, but limited lithium resources and high cost limit its development. The emerging potassium ion battery is widely focused by researchers due to the abundant reserves of potassium resources, low cost and similar physicochemical properties of potassium and lithium, and is considered to be capable of meeting the requirements of a large-scale energy storage system. In addition, potassium ion batteries have certain advantages in terms of voltage output due to the closer standard redox potential of potassium (-2.94 v vs. she) than sodium (-2.73 v vs. she) to lithium (-3.04 v vs. she). And the stoke radius of the solvation of the potassium ions in the electrolyte is smaller than that of lithium ions and sodium ions, so that the ion conductivity is higher, and the potassium ion battery can realize better rate capability. Unlike sodium ion batteries, which are limited by the inability of graphite cathodes to intercalate and deintercalate sodium ions, graphite has proven to be applicable to potassium ion batteries, which lays a good foundation for the practical application of potassium ion batteries. Although more and more researchers are currently devoting to the research of potassium ion battery materials, the high-energy density and excellent-cycle-performance potassium ion battery cathode materials still need to be further developed.
In material design, high Entropy (High Entropy) is an effective strategy to control crystal/electronic structure and properties. High entropy strategies are used to design alloys containing five or more metallic elements, and various high entropy alloys have been successful and widely used for thermocatalytic and electrocatalytic applications. Overall, high entropy alloys and oxides exhibit more flexible bulk and surface structures than alloys and oxides with fewer metallic elements, exhibiting excellent electrochemical performance.
The manganese-based layered oxide is considered as a positive electrode material with great prospect due to rich manganese resources, no toxicity, environmental protection and low cost. In addition, manganese is rich in valence (from Mn 2+ To Mn of 4+ ) The voltage range of the battery can be flexibly adjusted, and larger battery capacity is provided. K (K) 0.45 MnO 2 Related studies of materials (abbreviated as KMO) confirm that manganese-based layered oxides have potassium storage activity, however, the prior art has a number of problems, first: the KMO material has fast capacity attenuation and poor rate capability in the charge and discharge process; second,: when KMO powder is prepared by solid phase sintering, an orthorhombic crystal phase is obtained, so that the potassium storage capacity of the material is weakened, and larger volume change is generated in the charge and discharge process; third,: after solid phase sintering, when the KMO material is cooled and directly taken out, the layered oxide of the potassium electric positive electrode layered material is sensitive to the moisture in the air and is easy to be polluted by the water in the air, so that the electrochemical performance of the material is poor; fourth, K 0.45 MnO 2 Materials (including other materials from which they are derived) all have the problem of irreversible phase change during redox and are more prominent under high pressure conditions, and generally when the cut-off voltage is 4.0V or even above 4.2V, the irreversible phase change can significantly affect the running stability of the electrode material.
Meanwhile, in consideration of the fact that the radius of potassium ions is large, chemical reaction kinetics are slow in the ion deintercalation process, so that a corresponding electrode material needs to be developed for a potassium ion battery.
Disclosure of Invention
The technical problems to be solved by the invention are as follows: when the KMO material is applied to the positive electrode of the potassium ion battery, capacity fading is fast, rate capability is poor, and irreversible phase change exists in the process of cyclic charge and discharge.
The invention realizes high entropy strategy modification through a solid phase sintering process, synthesizes the P3-phase manganese-based layered high entropy oxide anode material, and the high entropy strategy is an effective strategy for controlling the crystal structure, the electronic structure and the performance, and the high entropy material shows more flexible bulk phase and surface structure, thereby obtaining excellent electrochemical performance.
In order to solve the problems set forth in the background art, the invention provides the following technical scheme:
a manganese-based layered high-entropy oxide positive electrode material has a molecular formula of: k (K) 0.5- x Mn 0.60 Ni y Fe y Co y Ti 0.10 Cu x Mg 0.1-y O 2 ，0.04<x<0.06，0.07<y<0.08。
Preferably, the molecular formula is specifically: k (K) 0.45 Mn 0.60 Ni 0.075 Fe 0.075 Co 0.075 Ti 0.10 Cu 0.05 Mg 0.025 O 2 。
Preferably, the preparation method of the manganese-based layered high-entropy oxide positive electrode material comprises the following steps:
(1) Weighing K2CO3, mnO2, niO, fe2O3, co2O3, tiO2, cuO and MgO according to the stoichiometric ratio, mixing with an auxiliary agent, and performing ball milling;
(2) And (3) ball milling, drying to obtain powder, and sintering after compression molding to obtain the manganese-based layered high-entropy oxide anode material.
Preferably, in the step (1), K 2 CO 3 The amount of (2) is 5% -10% excess relative to the stoichiometric ratio.
Preferably, in the step (1), the rotation speed of the ball milling is 300-400rpm, and the ball milling time is 5-8h.
Preferably, in the step (2), the drying temperature is 100-110 ℃, and the drying time is 12-15 hours; the sintering temperature is 800-900 ℃, the heat preservation sintering is carried out for 15-18h, the heating rate is 5-8 ℃/min, the furnace is cooled to 180-220 ℃ after the sintering is completed, and the material is taken out and transferred into an inert atmosphere to be continuously cooled to the room temperature.
A positive electrode of a potassium ion battery, which comprises the manganese-based layered high-entropy oxide positive electrode material.
Preferably, the positive electrode slurry used for the battery positive electrode comprises manganese-based layered high-entropy oxide positive electrode material, conductive agent and binder, wherein the weight ratio is 5-10:1-3:1.
the potassium ion battery comprises a battery shell, an electrode group and electrolyte, wherein the electrode group and the electrolyte are sealed in the battery shell, the electrode group comprises a positive electrode, a diaphragm and a negative electrode, and the potassium ion battery comprises the positive electrode of the potassium ion battery.
Preferably, the manganese-based layered high-entropy oxide positive electrode material is applied to the preparation of a positive electrode of a potassium ion battery.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention adopts a simple solid phase sintering method and adopts MnO 2 As a manganese source, the high-entropy strategy modification is realized, so that the material has more flexible bulk phase and surface structure, the capacity retention rate and the rate capability of the potassium ion battery in the charge-discharge cycle process are improved, and the electrochemical performance is improved.
(2) The HE-KMO is a P3 pure-phase material, the powder solid obtained by sintering does not generate a hybrid peak, the generation of an orthorhombic hybrid phase is inhibited, the HE-KMO is a single-phase reaction in the charge and discharge process, the HE-KMO has excellent structural stability, and the cycle performance and the multiplying power performance are improved; meanwhile, the HE-KMO can effectively reduce the charge transfer resistance of the electrode material in the charge-discharge process, and improve the circulation stability of the electrode material. The HE-KMO has stable oxide phase structure and no phase change in cyclic charge and discharge under the condition of a high voltage window.
(3) According to the invention, when the temperature is reduced to a specific temperature after sintering, the sample is transferred to the inert atmosphere for continuous cooling, so that the problem that the electrochemical performance of the material is poor due to water intercalation caused by the pollution of water in the air is avoided.
Drawings
FIG. 1, X-ray diffraction Rietveld refinement of HE-KMO and KMO;
FIG. 2, (a) is a Scanning Electron Microscope (SEM) image of HE-KMO; (b) Scanning Electron Microscope (SEM) images of KMO; (c) an element map image of HE-KMO;
FIG. 3, charge-discharge curves for HE-KMO (a) and KMO (b) at 0.1C for a voltage range of 1.5-4.2V;
FIG. 4, cyclic Voltammetric (CV) curves for HE-KMO (a) and KMO (b) at scan rates of 0.1mV/s over a voltage range of 1.5-4.2V;
FIG. 5, (a) is a graph comparing the ratio performance of HE-KMO and KMO, and the current densities are 0.1C, 0.5C, 1C, 2C, 5C, respectively; (b) A comparison graph of the cyclic performance of HE-KMO and KMO at 1C current density;
FIG. 6, (a) is a Nyquist diagram for the HE-KMO initial and charged states; (b) Nyquist plots for KMO initial and charged states; (c) EIS data equivalent circuit diagrams for fitting HE-KMO and KMO materials;
FIG. 7, (a) is an in situ XRD pattern of HE-KMO; (b) is the in situ XRD pattern of KMO.
FIG. 8, (a) is a dQ/dV diagram of HE-KMO; (b) is a dQ/dV diagram of KMO.
FIG. 9, a graph of the cyclic performance of HE-KMO at 5C current density.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
Preparation of HE-KMO (K) by solid phase sintering 0.45 Mn 0.60 Ni 0.075 Fe 0.075 Co 0.075 Ti 0.10 Cu 0.05 Mg 0.025 O 2 ): weighing K according to stoichiometric ratio 2 CO 3 、MnO 2 、NiO、Fe 2 O 3 、Co 2 O 3 、TiO 2 Adding CuO and MgO into a ball milling tank, dripping absolute ethyl alcohol, ball milling for 5 hours, and rotating the high-energy ball mill at a rotating speedAt 300rpm, several raw materials were thoroughly ground and mixed well. And then taking out the slurry obtained after mixing from the ball milling tank, and drying the slurry in a 100 ℃ oven for 12 hours. 0.5g of the dried powder was pressed into a sheet with a die having a diameter of 19mm and placed in an alumina crucible. And finally, placing the crucible with the wafer into a muffle furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 15 hours, cooling along with the furnace, taking out after the temperature is reduced to 200 ℃ (preventing the sample from absorbing water in humid air), transferring into an Ar atmosphere glove box, and grinding to obtain the black brown powder material HE-KMO.
Comparative example 1
Preparation of KMO (K) by solid phase sintering method 0.45 MnO 2 ): weighing K according to stoichiometric ratio 2 CO 3 、MnO 2 Adding the mixture into a ball milling tank, dropwise adding absolute ethyl alcohol, ball milling for 5 hours, and fully grinding and uniformly mixing several raw materials at the rotating speed of a high-energy ball mill of 300 rpm. And then taking out the slurry obtained after mixing from the ball milling tank, and drying the slurry in a 100 ℃ oven for 12 hours. 0.5g of the dried powder was pressed into a sheet with a die having a diameter of 19mm and placed in an alumina crucible. And finally, placing the crucible with the wafer into a muffle furnace, heating to 800 ℃ at a speed of 5 ℃/min, preserving heat for 15 hours, cooling along with the furnace, taking out after the temperature is reduced to 200 ℃ (preventing the sample from absorbing water in humid air), transferring into an Ar atmosphere glove box, and grinding to obtain the black brown powder material KMO.
Preparing an electrode: the active materials prepared in examples and comparative examples, acetylene black (as a conductive agent), PVDF (as a binder) were prepared in an Ar atmosphere glove box according to 7:2:1, then adding a proper amount of NMP, uniformly stirring to form slurry, uniformly coating the slurry on a flat aluminum foil, heating at 80 ℃ in a glove box transition cabin, heating to 120 ℃ after the surface is dried, vacuum drying for 10 hours, ensuring complete volatilization of an organic solvent, taking out, cutting into electrode slices with the diameter of 12mm, and weighing, wherein the carrying capacity of each electrode slice is 0.8-1.2mg/cm.
Assembling and testing of the battery: all cell assemblies were performed in an Ar atmosphere glove box. Using a CR2032 battery case (304 stainless steel material), the negative electrode was made of a potassium sheet (small pieces of potassium were cut out with a knife, rolled into a sheet, punched out), and the electrolyte was dissolved in Ethylene Carbonate (EC) and Propylene Carbonate (PC) using KPF6 at 1M, where EC: the volume ratio of PC is 1:1. the electrolyte consumption of each battery is 80 mu L, and the diaphragm adopts a glass fiber membrane. And sequentially assembling the cathode shell, the elastic sheet, the gasket, the potassium sheet, the diaphragm, the electrolyte, the electrode sheet and the anode shell into a half battery, and then packaging by a packaging machine. Taking out the glove box, standing for 10 hours, and performing electrochemical test. The charge and discharge test of the battery is carried out on a Land BT2000 battery test system of blue electric and electronic battery test Limited in Wuhan, wherein the test temperature is room temperature, the voltage test window is 1.5-4.2V, all the batteries are kept stand for 10 hours, and various required tests are carried out. The current density of 1C in all electrochemical tests herein was 100mA/g. The impedance analysis of the cell was characterized by EIS using an United states impedance analyzer (Solartron 1287 versus Solartron 1260) at a frequency in the range of 1MHz to 0.01Hz.
Test example 1: characterization of materials
The structure of the material is obtained through XRD testing, GENERAL STRUCTURE ANALYSIS II software (GSAS II) is adopted, and the XRD pattern is refined by using the Rietveld method. The appearance and the size of the material are appearance characterization by using SEM, and the element distribution condition and the element content of the prepared sample are characterized by EDS and ICP-MS tests. The potassium storage behavior of the material in the charge and discharge process is characterized by in-situ XRD, in-situ XRD test is that a perforated in-situ CR2032 battery shell is sealed by an X-ray permeable aluminum film, and XRD signals collected while electrochemical test is carried out, so that an in-situ XRD spectrogram is obtained.
(1) A Kapton film was used to seal the sample during XRD testing, so a background between 12-30 ° was associated with Kapton films. FIG. 1 is a Rietveld refinement XRD pattern of the two materials, from which it can be seen that HE-KMO belongs to the P3 phase structure, with a space group of R-3m; KMO belongs to the P'3 phase structure, and the space group is C2/m.
The above results indicate that the high entropy strategy suppresses the generation of orthorhombic phases. The HE-KMO XRD spectrum has no impurity peak, which indicates that Fe, co, ni, mg, ti, cu element successfully enters the main material, and the modification of the material structure by a high entropy strategy is realized.
(2) The contents of metal elements in the materials were analyzed by ICP, and the compositions of HE-KMO and KMO were confirmed after normalizing the obtained results with respect to the total number of transition metals, and the ICP results are shown in table 1, which substantially match the designed target compositions. Rietveld refinement is carried out on XRD data of the two materials by using GSAS II software, a refinement diagram is shown in figure 1, and the fitting curve of the two materials after refinement can be seen to be better overlapped with experimental measured data. The parameters obtained from both refinements are summarized in table 2. Wherein the lattice parameter of the HE-KMO is And KMO has a lattice parameter of +.>
Table 1 ICP results of the metal content in the materials HE-KMO and KMO
TABLE 2 XRD refinement results for materials HE-KMO and KMO
The results of the XRD refinement described above demonstrate that the high entropy strategy causes KMO to convert from the original P'3 phase to the P3 phase of HE-KMO, resulting in an increase in the lattice parameter c of the material and the unit cell volume V. The interlayer spacing of the material is increased, so that the diffusion of potassium ions in a crystal structure is facilitated, and the charge and discharge performance of the potassium ion battery is improved.
(3) The microscopic morphology and size of the two materials were characterized by Scanning Electron Microscopy (SEM), and fig. 2 (a) (b) are microscopic morphologies of HE-KMO and KMO, respectively, and the particle size of both materials was about 1 μm, and the phenomenon of agglomeration of particles was accompanied. The morphology of the two materials is in a hexagonal prism shape, the side surface of the hexagonal prism corresponds to a {010} surface, and potassium ions diffuse through the surface. The HE-KMO hexagonal prism has a larger volume and side height than KMO, and the average height of the HE-KMO hexagonal prism is about 0.26 μm, while KMO is only 0.1 μm, indicating that the HE-KMO has more potassium ion diffusion paths. Fig. 2 (c) shows a mapping diagram of each element in the HE-KMO material, and it can be seen that each element is in a uniformly distributed state.
Test example 2: electrochemical performance comparative analysis
(1) The charge-discharge curves of the two are shown in FIG. 3 at 0.1C rate in the voltage interval of 1.5-4.2V, and (a) and (b) are HE-KMO and KMO respectively. As can be seen from the figure, although KMO materials provided a discharge capacity of 141.2mAh/g during the first round of charge and discharge, as the charge and discharge test progressed, they showed severe capacity decay, and when cycled to round 3, their discharge capacities had decayed to 109.7mAh/g. The HE-KMO material modified by the high-entropy strategy has the discharge capacity of 106.8mAh/g at the first circle, but has the discharge capacities of 99.5mAh/g and 97.3mAh/g at the 2 nd circle and the 3 rd circle respectively, and almost no capacity attenuation after the irreversible capacity of the first circle is removed.
Therefore, the HE-KMO material improves the capacity retention rate of the potassium ion battery during charge and discharge cycles. In addition, HE-KMO materials also have smoother linear charge-discharge curves and fewer voltage plateaus compared to KMO materials, indicating that HE-KMO is extremely reversible.
(2) FIG. 4 is Cyclic Voltammetry (CV) curves corresponding to the first 3 cycles of charge and discharge curves of HE-KMO and KMO, and (a) (b) are HE-KMO and KMO, respectively. As can be seen from FIG. 4 (a), the CV curve of the HE-KMO material has a pair of relatively obvious redox peaks near 2.6/2.4V, which are consistent with the voltage plateau appearing on the charge-discharge curve, and the curves of each circle can be well overlapped, which indicates that the HE-KMO material has relatively good cycle stability and reversibility. The CV curve of the inverted KMO material, it can be seen that there are many irreversible redox peaks and extremely misaligned curves, meaning poor reversibility, cycling stability. Compared to HE-KMO, KMO has two high-intensity oxidation peaks in the high voltage region (3.8V and above), which corresponds to the large voltage plateau of the charging curve in the high voltage region, and no reduction peaks correspond to it, which also confirms that irreversible structural changes in the material structure occur at high voltages, resulting in subsequent capacity fading. Notably, the voltage difference of the redox peaks of the HE-KMO material is much smaller than KMO, indicating that the HE-KMO material has smaller polarization and good dynamic characteristics.
These electrochemical test results indicate that HE-KMO has better structural stability than KMO.
(3) Fig. 5 (a) shows the rate capability of the materials HE-KMO and KMO. The discharge capacities of the KMO material at 0.1C and 5C are 141.2mAh/g and 7.5mAh/g respectively; the HE-KMO material has discharge capacities of 106.8mAh/g and 39.6mAh/g at 0.1C and 5C, respectively. Compared with KMO material, the HE-KMO material has better rate capability and can still provide good capacity at high rate. The result of the rate performance test shows that the high-entropy strategy modification improves the rate performance of the material. To examine the long-cycle stability of the materials, we performed a 200-cycle test at 1C rate for the materials HE-KMO and KMO, respectively. Fig. 5 (b) shows the long cycle performance of the materials HE-KMO and KMO at 1C magnification. The cycling test results show that the KMO and HE-KMO materials have capacity retention (based on circle 3) of 17.3% and 60.4%, respectively, after 200 cycles at 1C rate.
These electrochemical test results indicate that HE-KMO materials exhibit excellent overall properties, particularly rate capability and cycling stability.
(4) Electrochemical alternating current impedance (EIS) tests are commonly used to determine the stability of electrode materials. To further investigate the interfacial stability of the materials HE-KMO and KMO, we tested the AC impedance of the as-charged and as-charged cells between 1MHz-0.01Hz, and FIG. 6 (a) (b) is a Nyquist plot of the as-charged and as-charged HE-KMO, respectively. Each curve in the figure shows a semicircle connected with a small diagonal line, which is consistent with the Nyquist curve of other layered materials of the potassium ion battery. In the high frequency region, the intersection of the curve and the real axis (Z') is the resistance (Rs) related to the solution resistance and the like, and the semicircular arc reflects the charge transfer resistance (Rct) of the electrode. The slope of the low frequency region reflects the Warburg impedance (Zw) associated with the potassium ion diffusion coefficient. By means of the Z-view software, the Nyquist curves of both were fitted with an equivalent circuit as shown in FIG. 6 (c). First, the HE-KMO has 495.9 Ω and less than 1679 Ω of KMO, compared to the charge transfer resistor (Rct) in the initial state. After charging to 4.2V, HE-KMO only had 3128Ω, while KMO increased to 11876 Ω, although the Rct value of both materials increased. The rapid increase of the charge transfer resistance of the electrode material in the charge-discharge process tends to cause the deterioration of the cycle performance, and the high-entropy strategy change can effectively reduce the resistance of the material.
The result shows that the high-entropy strategy modification can effectively improve the cycling stability of the electrode material, and in addition, the smaller impedance value also corresponds to the HE-KMO material with better rate capability.
Test example 3: structural change of material in charge-discharge process
(1) To further investigate the structural evolution of the materials HE-KMO and KMO during the electrochemical reaction, XRD data of the materials during the first and second charge-discharge cycles were collected using in-situ XRD techniques, and fig. 7 (a) (b) are in-situ XRD images of HE-KMO and KMO, respectively. As can be seen from the graph, during the first charge-discharge cycle and the second charge cycle of the HE-KMO material, the characteristic peaks (003) and (006) of the P3 phase shift to the low angle first, then shift to the high angle to stop at the end of discharge, and then shift to the low angle again to stop at the end of charge, which indicates that the lattice parameter c of the material increases first and then decreases and then increases. This is due to the release of potassium ions during charge and discharge, and the electrostatic repulsive force of oxygen between layers is changed. In this process, (101) and (102) characteristic peaks are shifted to a high angle, then shifted to a low angle until the end of discharge is stopped, and then shifted to a high angle again until the end of charge is completed. This means that the lattice parameter a decreases during charging and increases during discharging, which is caused by the increase in valence of each transition metal element during charging and the corresponding decrease in ionic radius, whereas the discharging process is reversed. The charge-discharge process of the HE-KMO material is a P3 phase solid solution process, and phase change does not occur. The in-situ XRD result shows that the material HE-KMO has high reversibility in the charge-discharge process and good structural stability, and the reason that the HE-KMO has good cycle performance is also explained. The KMO material undergoes a phase change during charging from P'3 phase to P "3 phase, and when charged to a high voltage of 4.2V, the main peak of the material gradually disappears, meaning a severe disruption of the material structure.
As shown in fig. 8 (a) (b), the dQ/dV curves obtained after differentiating the electrochemical curves of HE-KMO and KMO at the first turn in the voltage range of 1.5-4.2V show that: KMO shows a high intensity oxidation peak at high voltage, but no reduction peak corresponds to it, which also confirms that an irreversible structural change of the material structure occurs at high voltage, resulting in subsequent capacity fade. Under the condition of reversely watching HE-KMO and charging to 4.2V, no oxidation peak appears in a high potential interval (> 4.0V), which indicates that the HE-KMO does not generate phase change in the charging process and has excellent structural stability, so that the HE-KMO can show excellent long-cycle stability in a wide voltage interval. Thus, long cycle performance testing was performed on HE-KMO with capacity retention up to 65.3% after 200 cycles at high rate 5C over a voltage range of 1.5-4.2V (fig. 9). In addition, the coulombic efficiency curve of HE-KMO is extremely steady throughout the cycle, with an average coulombic efficiency as high as 99.79% (excluding the abnormal coulombic efficiency of the first cycle due to the potassium-depleted system), indicating that HE-KMO loses less capacity during each charge/discharge cycle, with excellent cycle life.
Therefore, the structural stability of the KMO material is greatly improved by the high-entropy strategy modification.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims (10)

1. The manganese-based layered high-entropy oxide positive electrode material is characterized by having a molecular formula of: k (K) 0.5- x Mn 0.60 Ni y Fe y Co y Ti 0.10 Cu x Mg 0.1-y O 2 ，0.04<x<0.06，0.07<y<0.08。
2. The manganese-based layered high entropy oxide positive electrode material according to claim 1, wherein the molecular formula is specifically: k (K) 0.45 Mn 0.60 Ni 0.075 Fe 0.075 Co 0.075 Ti 0.10 Cu 0.05 Mg 0.025 O 2 。
3. The method for preparing the manganese-based layered high-entropy oxide positive electrode material according to claim 1, comprising the steps of:
(1) Weighing K according to stoichiometric ratio 2 CO 3 、MnO 2 、NiO、Fe 2 O 3 、Co 2 O 3 、TiO 2 Mixing CuO and MgO with an auxiliary agent and then ball milling;
(2) And (3) ball milling, drying to obtain powder, and sintering after compression molding to obtain the manganese-based layered high-entropy oxide anode material.
4. The method for preparing a manganese-based layered high-entropy oxide positive electrode material according to claim 3, wherein in the step (1), K 2 CO 3 The amount of (2) is 5% -10% excess relative to the stoichiometric ratio.
5. The method for preparing a manganese-based layered high-entropy oxide cathode material according to claim 3, wherein in the step (1), the rotation speed of ball milling is 300-400rpm, and the ball milling time is 5-8 hours.
6. The method for preparing a manganese-based layered high-entropy oxide positive electrode material according to claim 3, wherein in the step (2), the drying temperature is 100-110 ℃, and the drying time is 12-15 hours; sintering at 800-900 deg.c for 15-18 hr at 5-8 deg.c/min; and cooling to 180-220 ℃ along with the furnace after sintering, taking out the material, transferring the material into an inert atmosphere, and continuously cooling to room temperature.
7. A positive electrode for a potassium ion battery, comprising the manganese-based layered high entropy oxide positive electrode material of claim 1.
8. The positive electrode of the potassium ion battery according to claim 7, wherein the positive electrode slurry used for the positive electrode of the battery comprises manganese-based layered high-entropy oxide positive electrode material, conductive agent and binder, and the weight ratio is 5-10:1-3:1.
9. a potassium ion battery comprising a battery housing, an electrode set and an electrolyte, the electrode set and the electrolyte being sealed within the battery housing, the electrode set comprising a positive electrode, a separator and a negative electrode, wherein the potassium ion battery comprises a potassium ion battery positive electrode as claimed in claim 7 or 8.
10. The use of the manganese-based layered high entropy oxide positive electrode material according to claim 1 for preparing positive electrode of potassium ion battery.
CN202311150699.5A 2023-09-07 2023-09-07 Manganese-based layered high-entropy oxide positive electrode material and preparation method thereof Pending CN117334892A (en)

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Publication number Priority date Publication date Assignee Title
CN114628677A (en) * 2020-12-03 2022-06-14 南京大学 Copper-doped potassium manganate electrode material, preparation method thereof and application thereof in potassium ion battery
CN114883522A (en) * 2022-04-20 2022-08-09 南京邮电大学 High-entropy-like multi-element layered transition metal oxide cathode material and preparation method and application thereof
CN115872462A (en) * 2023-01-04 2023-03-31 中国地质大学（北京） Preparation method of high-entropy oxide positive electrode material of potassium ion battery
CN116605918A (en) * 2023-03-15 2023-08-18 北京航空航天大学 High-entropy doped O3 phase layered oxide, preparation method thereof, sodium ion battery positive electrode material and battery

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114628677A (en) * 2020-12-03 2022-06-14 南京大学 Copper-doped potassium manganate electrode material, preparation method thereof and application thereof in potassium ion battery
CN114883522A (en) * 2022-04-20 2022-08-09 南京邮电大学 High-entropy-like multi-element layered transition metal oxide cathode material and preparation method and application thereof
CN115872462A (en) * 2023-01-04 2023-03-31 中国地质大学（北京） Preparation method of high-entropy oxide positive electrode material of potassium ion battery
CN116605918A (en) * 2023-03-15 2023-08-18 北京航空航天大学 High-entropy doped O3 phase layered oxide, preparation method thereof, sodium ion battery positive electrode material and battery

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