Preparation method of copper-doped binary manganese-based layered oxide positive electrode material, positive electrode material and application

Abstract

The application provides a preparation method of a copper-doped binary manganese-based layered oxide positive electrode material, a positive electrode material and application. A copper salt is used as a dopant, a copper element is doped into a manganese-based oxide by using a sol-gel method to obtain a precursor solution, and then high-temperature heat treatment is performed to obtain the copper-doped binary manganese-based layered oxide positive electrode material. The preparation process is as follows: (1) adding various potassium salts, manganese salts, copper salts and binders in deionized water, and stirring until completely dissolved to obtain a precursor; (2) drying the solution obtained in (1); (3) grinding the fluffy solid after drying in (2) into fine particles; and (4) high-temperature calcining the fine particles obtained by grinding in (3) to obtain a copper-doped binary manganese-based layered oxide positive electrode material powder. The application has the characteristics of simple process, low cost and large-scale production, and the positive electrode material has high specific capacity, good cycle stability and excellent rate performance as a positive electrode of a potassium ion battery.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemistry, and particularly relates to a preparation method of a copper-doped binary manganese-based layered oxide positive electrode material, a positive electrode material and application. TECHNICAL BACKGROUND

[0002] Lithium ion batteries (LIBs) have been widely used in mobile electronic devices, electric vehicles and energy storage fields due to their high energy density and excellent performance. However, there are some limitations in lithium ion batteries, such as limited resources, high cost and the like. Therefore, researchers begin to explore other alkali metal ion batteries as an alternative solution, among which potassium ion batteries are concerned due to their abundant resources, high energy density, easy commercialization and the like. However, due to the large ionic radius of K + ions, the embedding / extraction process will cause serious damage to the framework structure of the material, which seriously affects the actual rate performance and cycle life of PIBs, and therefore it is necessary to study a potassium ion positive electrode material with a stable framework structure after K + extraction.

[0003] In recent years, significant progress has been made in the research of PIBs positive electrode materials, and the number of literatures reported has gradually increased. The reported PIBs positive electrode materials can be divided into four categories: layered transition metal oxides, metal hexacyanometallates, organic compounds and polyanionic compounds. Metal hexacyanometallate compounds, such as Prussian blue (white), have very high specific capacity but poor electronic conductivity, and the rate performance is difficult to improve. Organic electrode materials have the advantages of renewable, green and high capacity, but they are highly soluble in electrolyte and have poor conductivity, which greatly limits the application of organic positive electrode materials in PIBs. Polyanionic compounds usually have high electrochemical reaction stability and working voltage, but the disadvantages are that the ion and electronic conductivity of such materials is low, and the large molecular weight also reduces the specific capacity. Among these candidate materials, layered transition metal oxides (A x MO2, A = K, Na and combinations thereof; M = V, Mn, Fe, Ni, Cr, Co and combinations thereof) are particularly promising, because of their unique layered structure, which can accommodate larger potassium ion embedding and extraction, and the synthesis method is simple, the output voltage is high, and it can be used as a good potassium ion battery positive electrode material.

[0004] In layered transition metal oxides, manganese-based layered oxides have stable crystal structure in addition to the advantages of low cost and environmental friendliness. When the layered oxide contains more manganese elements, the structure of the material is relatively stable, relatively easy to synthesize, and not prone to phase separation. Therefore, manganese-based layered oxides have been widely studied in potassium ion battery cathode materials. However, manganese-based layered oxides still face problems such as poor cycle performance, poor rate performance and low actual capacity, which limit their future commercial application.

[0005] The main reason for poor cycle performance is essentially the Jahn-Teller effect in manganese-based layered oxides. Generally, manganese in the material exists in mixed valence states of +3 and +4. Among them, the tetravalent manganese (Mn 4+ ) does not produce Jahn-Teller effect, forming a distortion-free [MnO6] octahedron in the material, thereby obtaining a stable crystal structure. However, the high-spin trivalent manganese (Mn 3+ ) with (t2g) 3 (eg) 1 electronic configuration in the 3d electron orbital will produce Jahn-Teller effect. This Jahn-Teller effect will cause distortion of [MnO6] octahedron in the material, reduce the symmetry and energy of the nonlinear molecular system, lead to structural disorder and strong internal stress, and ultimately cause instability of the crystal structure. In addition, during the charging and discharging process, the valence state of manganese will change between +3 and +4, causing the Jahn-Teller effect in the material to repeatedly eliminate and produce, ultimately leading to an irreversible multi-phase transition process, further affecting the structural stability of the material.

[0006] To solve these problems, researchers have tried various strategies, such as element doping, surface coating, core-shell structure, etc. Among them, element doping is an effective strategy to solve the above problems. Commonly used doping elements include Mg, Ni, Ti, etc. The doping of these elements has a significant improvement effect on the overall structure and performance of the material. By using copper element doping, which is widely available, the structural stability of the material itself is improved, the rate performance is improved, and the cost is effectively saved, which can better commercialize.

[0007] Therefore, synthesizing copper-doped binary manganese-based layered oxide cathode materials is of great significance to promote the development of high-specific-energy and high-stability potassium ion batteries. SUMMARY

[0008] The purpose of the present application is to adjust the average valence of Mn to suppress the Jahn-Teller effect of manganese-based layered oxide cathodes, and to synthesize a P3 phase by copper doping, high Mn 4+ / Mn 3+The application discloses a high specific capacity, high specific capacity, high stability, simple process, low cost and large-scale production potassium ion battery positive electrode material. The average valence of Mn is adjusted to inhibit the Jahn-Teller effect of the manganese-based layered oxide positive electrode, and the cycle stability is improved. The preparation method of the high specific capacity and high stability PIBs positive electrode material is obtained, and the material can be used as the high specific capacity and long service life PIBs positive electrode material.

[0009] The technical scheme for solving the above problems is as follows: a P3 phase layered structure with high specific capacity is synthesized by proper material ratio, and a high Mn 4+ / Mn 3+ specific capacity is obtained by doping Cu, the average valence of Mn is improved, the Jahn-Teller effect is inhibited, and the Cu 2+ interlayer spacing in the layered structure is widened, the diffusion of K + is accelerated, and the ion diffusion dynamics ability is promoted.

[0010] The preparation method of the material comprises the following steps:

[0011] (1) adding various potassium salts, manganese salts, copper salts and binders in deionized water, and stirring until completely dissolved to obtain a precursor;

[0012] (2) drying the solution obtained in the step (1);

[0013] (3) grinding the fluffy solid after drying in the step (2) into fine particles;

[0014] (4) high-temperature calcining the fine particles obtained in the step (3) to finally obtain a copper-doped binary manganese-based layered oxide positive electrode material;

[0015] According to the above scheme, the potassium salt in the step (1) is potassium nitrate, the manganese salt is manganese acetate tetrahydrate, the copper salt is copper acetate monohydrate, the binder is polyvinylpyrrolidone (PVP K90, Mw=1 300 000), and the acid is oxalic acid.

[0016] According to the above scheme, the amount of the potassium salt in the step (1) is 5% more than that, and the PVP is added in batches in the interval of adding various materials.

[0017] According to the above scheme, the synthesis process in the step (1) is heated and stirred in a water bath, the stirring speed is 400-600 r / min, the heating temperature is 60-80 DEG C, and the duration is 5-6 h.

[0018] According to the above scheme, the drying temperature in the step (3) is 110-140 DEG C, and the drying time is 10-13 h.

[0019] According to the above scheme, in step (4), the calcination atmosphere is air, the pre-calcination temperature is 490-500 DEG C, the temperature rising speed is 5-6 DEG C / min, the calcination time is 2-3 h, and then the final calcination temperature is 900-920 DEG C, the temperature rising speed is 5-6 DEG C / min, and the calcination time is 12-14 h.

[0020] The present application has the following advantages:

[0021] (1) A stable P3 phase layered structure material is synthesized.

[0022] (2) The average valence of Mn is improved, the Jahn-Teller effect is inhibited, and the potassium ion diffusion rate is improved.

[0023] (3) High capacity, high rate and high stability are considered, and the assembled half battery shows excellent electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the XRD pattern of the product of Example 2 of the present application and the product of Example 1.

[0025] Figure 2 is the XPS pattern of Mn2p of the product of Example 2 of the present application.

[0026] Figure 3 is the XPS pattern of Cu2p of the product of Example 2 of the present application.

[0027] Figure 4 is the charge-discharge curve of the half battery assembled by the positive electrode material obtained in Example 2 of the present application at different cycles under a current density of 200 mA / g.

[0028] Figure 5 is the rate performance comparison chart of the half battery assembled by the positive electrode material obtained in Example 2 and Example 1 of the present application under different current densities.

[0029] Figure 6 is the cycle performance comparison chart of the half battery assembled by the positive electrode material obtained in Example 2 and Example 1 of the present application under a current density of 100 mA / g after 100 cycles.

[0030] Figure 7 is the cycle performance chart of the half battery of Example 2 of the present application under a large current density of 1 A / g after 700 cycles.

[0031] Figure 8 is the electrochemical impedance comparison chart of the half battery assembled by the positive electrode material obtained in Example 2 and Example 1 of the present application. DETAILED DESCRIPTION

[0032] For better understanding of the present application, the following further illustrates the content of the present application in conjunction with examples, but the content of the present application is not limited to the following examples only. The technical solutions of the present application are described in conjunction with the accompanying drawings and examples.

[0033] A preparation method of a copper-doped binary manganese-based layered oxide positive electrode material, comprising the following steps:

[0034] (1) Adding various potassium salts, manganese salts, copper salts, binders, and acids in deionized water and stirring until completely dissolved to obtain a precursor.

[0035] (2) Drying the solution obtained in step (1).

[0036] (3) Grinding the fluffy solid after drying in step (2) into fine particles.

[0037] (4) High-temperature calcining the fine particles obtained in step (3) to finally obtain a copper-doped binary manganese-based layered oxide positive electrode material.

[0038] In step (1), the potassium salt is potassium nitrate, the manganese salt is manganese acetate tetrahydrate, the copper salt is copper acetate monohydrate, the binder used is polyvinylpyrrolidone, and the acid used is oxalic acid.

[0039] The binder used is polyvinylpyrrolidone K90 (PVP K90), with a molecular weight of 1 300 000 (Mw = 1300 000); in step (1), the amount of potassium salt used is more than 5% of the calculated amount, and the polyvinylpyrrolidone (PVP) is added in batches between the addition of various materials. The oxalic acid is used to neutralize the excess byproducts, potassium nitrate (KNO3), manganese acetate tetrahydrate (C4H 14 MnO8), and copper acetate monohydrate (Cu(CO2CH3)2·H2O) are calculated as follows:

[0040] The chemical formula K 0.5 Mn 0.9 Cu 0.1 O2 in the following discussed Example 1 is 0.5:0.9:0.1 mmol, and for easy weighing, it is converted to 1:1.8:0.2 mmol, and in the conversion to mass ratio, it is 1.01103 g:4.65671 g:0.19965 g. Furthermore, the amount of potassium nitrate used is more than 5% of the calculated amount (1.01103 g), so the actual amount of potassium nitrate used is 1.06155 g (heating and stirring in a water bath will cause volatilization of the potassium salt).

[0041] The chemical formula K 0.5 Mn 0.95Cu 0.05 02, similar to the above, first element ratio K:Mn:Cu is 0.5:0.95:0.05, for the convenience of weighing into 1:1.9:0.1, so the three materials of potassium nitrate KNO3, four water and manganese acetate C4H 14 MnO8, one water and copper acetate Cu(CO2CH3)2·H2O are also 1:1.9:0.1 mmol, and the mass ratio is 1.01103g:4.41162g:0.3993g. Furthermore, the amount of potassium nitrate should be more than 5% of the calculated amount (1.01103g), so the actual amount of potassium nitrate is 1.06155g.

[0042] In the following example 3, the chemical formula K 0.5 Mn 0.85 Cu 0.15 O2, K:Mn:Cu=0.5:0.85:0.15, for the convenience of weighing into 1:1.7:0.3, and the mass ratio is 1.01103g:4.16653g:0.59895g, and the amount of potassium nitrate should be more than 5% of the calculated amount (1.01103g), so the actual amount of potassium nitrate is 1.06155g. Furthermore, in the specific order of addition, PVP is a binder, and one-time addition will cause its own clumping, and the adhesion of other substances will not be so good, and batch addition can be added while stirring and adhering, oxalic acid and potassium nitrate are the first and last to be added, and the order of the two intermediate substances, manganese acetate tetrahydrate, one water and copper acetate, can be exchanged

[0043] In step (1), the synthesis process is heated and stirred in a water bath, the stirring speed is 400-600r / min, the heating temperature is 60-80℃, and the duration is 5-6h.

[0044] In step (3), the drying temperature is 110-140℃, and the drying time is 10-13h.

[0045] In step (4), the calcination atmosphere is air, the precalcination temperature is 490-500℃, the heating rate is 5-6℃ / min, the calcination time is 2-3h, and then the final calcination temperature is 900-920℃, the heating rate is 5-6℃ / min, and the calcination time is 12-14h. After the precalcination in step (4) is completed, it is ground once, and the final calcination is cooled to 150-200℃ and quickly transferred to a glove box for storage.

[0046] The scheme relates to a copper-doped binary manganese-based layered positive electrode material, which is prepared by the above preparation method.

[0047] The present solution relates to a copper-doped binary manganese-based layered cathode material, the molar ratio of the doped metal element copper to the base manganese element being 1:9.

[0048] The present solution relates to the use of a copper-doped binary manganese-based layered cathode material as claimed in the claims as a cathode material for potassium ion batteries.

[0049] Example 1

[0050] The preparation method of the copper-doped binary manganese-based layered oxide cathode material comprises the following steps:

[0051] (1) 4 g of oxalic acid, 1 g of PVP, 4.65671 g of manganese acetate tetrahydrate, 1 g of PVP, 0.19965 g of copper acetate monohydrate, 1 g of PVP, and 1.06155 g of potassium nitrate, 1 g of PVP, are sequentially added to 40 ml of deionized water under continuous stirring, and heated in a water bath kettle. The heating temperature is 70°C, and the stirring speed is 500 r / min for 5 h.

[0052] (2) The solution obtained in (1) is transferred to a 100 ml corundum crucible, sealed with aluminum foil and a small air hole is punched on it, and placed in a 120°C oven for drying for 12 h.

[0053] (3) The fluffy sponge-like solid obtained in (2) is scraped off from the crucible and transferred to a mortar for grinding to obtain fine particles.

[0054] (4) The mixed particles in (3) are placed in a porcelain boat, and the porcelain boat is placed in a muffle furnace, heated to 500°C at a heating rate of 5°C / min under air atmosphere, and heat treated for 2 h. After taking out, it is ground again, and then heated to the final temperature of 900°C at a heating rate of 5°C / min, and heat treated for 12 h. After annealing, a copper-doped binary manganese-based layered oxide cathode material is obtained (the sample needs to be transferred to an argon glove box for storage when the muffle furnace is cooled to 100-150°C).

[0055] Example 2

[0056] The preparation method of the copper-doped binary manganese-based layered oxide cathode material comprises the following steps:

[0057] (1) 4 g of oxalic acid, 1 g of PVP, 4.65671 g of manganese acetate tetrahydrate, 1 g of PVP, 0.19965 g of copper acetate monohydrate, 1 g of PVP, and 1.06155 g of potassium nitrate, 1 g of PVP, are sequentially added to 40 ml of deionized water under continuous stirring, and heated in a water bath kettle. The heating temperature is 70°C, and the stirring speed is 500 r / min for 5 h.

[0058] (2) The solution obtained in (1) was transferred to a 100 ml corundum crucible, sealed with aluminum foil and a small hole was punched on the foil, and placed in a 120 °C oven for drying for 12 h.

[0059] (3) The fluffy sponge-like solid obtained in (2) was scraped off from the crucible and transferred to a mortar for grinding to obtain fine particles.

[0060] (4) The mixed particles in (3) were placed in a porcelain boat, and the porcelain boat was placed in a muffle furnace, and heated to 500 °C at a heating rate of 5 °C / min in an air atmosphere for 2 h, and then ground again, and then heated to a final temperature of 900 °C at a heating rate of 5 °C / min, and held for 12 h. After annealing, a copper-doped binary manganese-based layered oxide positive electrode material was obtained (the sample needs to be transferred to an argon glove box for storage when the muffle furnace is cooled to 100-150 °C).

[0061] Example 3

[0062] A method for preparing a copper-doped binary manganese-based layered oxide positive electrode material, comprising the following steps:

[0063] (1) 4 g of oxalic acid, 1 g of PVP, 4.16653 g of manganese acetate tetrahydrate, 1 g of PVP, 0.59895 g of copper acetate monohydrate, 1 g of PVP, 1.06155 g of potassium nitrate, and 1 g of PVP were sequentially added to 40 ml of deionized water under continuous stirring, and heated in a water bath. The heating temperature was 70 °C, and the stirring speed was 500 r / min for 5 h.

[0064] (2) The solution obtained in (1) was transferred to a 100 ml corundum crucible, sealed with aluminum foil and a small hole was punched on the foil, and placed in a 120 °C oven for drying for 12 h.

[0065] (3) The fluffy sponge-like solid obtained in (2) was scraped off from the crucible and transferred to a mortar for grinding to obtain fine particles.

[0066] (4) Put the mixed particles in (3) into a porcelain boat, and place the porcelain boat in a muffle furnace, and heat to 500°C at a temperature increasing rate of 5°C / min under an air atmosphere, and keep for 2 h, take out and perform secondary grinding, and then heat to a final temperature of 900°C at a temperature increasing rate of 5°C / min, and keep for 12 h. The copper-doped binary manganese-based layered oxide positive electrode material is obtained after annealing (the sample needs to be timely transferred to an argon glove box for storage when the muffle furnace is cooled to 100-150°C). Electrode material preparation and assembly process: mix 70 mg of the prepared copper-doped binary manganese-based layered oxide positive electrode material, 20 mg of Super P, and 10 mg of PVDF5130, and disperse in 900 μl of N-methyl pyrrolidone, transfer the above substances to a ball milling tube containing 5 large (d=3 mm) and 5 small (d=2 mm) zirconium oxide milling beads, use a high-speed vibration ball mill at a vibration frequency of 4000 r / min, mill for 2 min, cool for 1 min, and mill for 2 min to form a uniform slurry, then draw a 6.5*6.5 cm square on an aluminum foil, evenly coat the slurry in the square, and then dry on a heating table at 70-80°C for 10-12 h to obtain a positive electrode material. The electrode sheet is prepared by cutting the aluminum foil into an electrode disc with a diameter of 8 mm, and the active material mass loading of the cut electrode sheet is 1.5-2.5 mg / cm 2 . A CR2016 button cell is assembled in an argon atmosphere glove box with metallic potassium as the negative electrode, a glass fiber separator Whatman GF / D as the battery separator, and 0.8 mol / L KPF6 dissolved in ethylene carbonate (EC) and diethyl carbonate (DEC) with a volume ratio of 1:1 as the electrolyte, and the electrochemical performance of the battery is tested (1.5-3.9V).

[0067] The K 0.5 Mn 0.9 Cu 0.1 O2 product prepared in this example 2 has an XRD pattern as shown in Figure 1 , and the XRD image shows that the K 0.5 Mn 0.9 Cu 0.1 O2 is a P3 phase layered material without any impurities, and belongs to the R-3m space group (PDF #30-0950). The (101) characteristic peak of the product of this example 2 is shifted to a small angle compared with the product of example 1, which proves that the interlayer spacing of the material prepared in example 2 is expanded to a greater extent than the product of example 1, which is more conducive to the deintercalation of potassium ions. The XPS pattern of the K 0.5 Mn 0.9 Cu 0.1 O2 product prepared in this example 2 is shown in Figure 2 and Figure 3 , and the Mn 4+ / Mn3+ The ratio is larger than Example 1, indicating that the average valence of Mn is adjusted, and the adjustment degree of Example 2 is better than that of Example 1, the successful doping of Cu and the change of valence do not occur. The K 0.5 Mn 0.9 Cu 0.1 The charge-discharge curves of the O2 electrode material and the potassium metal assembled button cell at different cycles at a current of 200 mA / g are shown in Figure 4 The discharge specific capacity is as high as 85.5 mAh / g, and the charge-discharge curves are basically consistent, proving that it has excellent cycle charge-discharge capacity. The K 0.5 Mn 0.9 Cu 0.1 The rate performance of the O2 electrode material and the potassium metal assembled button cell at different current densities is shown in Figure 5 When the current density gradually increases from 50 mA / g to 100, 200, 500, 1000 and then returns to 100 mA / g, the specific capacity is 106.8, 91.1, 85.3, 68.2, 60.8, 91.4 mAh / g, respectively, showing that it has excellent rate performance. The K 0.5 Mn 0.9 Cu 0.1 The cycle performance of the O2 electrode material and the potassium metal assembled button cell at a current density of 100 mA / g is shown in Figure 6 After 100 cycles, it still has a specific capacity of 74.2 mAh / g, and the capacity retention rate is 82.3%, proving that it has excellent cycle stability. The K 0.5 Mn 0.9 Cu 0.1 The cycle performance of the O2 electrode material and the potassium metal assembled button cell at a large current density (1000 mA / g) is shown in Figure 7 After 700 cycles, it still has a specific capacity of 42 mAh / g, and the capacity retention rate is 66%, proving that it has excellent large-current cycle performance. The K 0.5 Mn 0.9 Cu 0.1 The electrochemical impedance spectrogram of the O2 electrode material and the potassium metal assembled button cell is shown in Figure 8 It shows that it has low charge transfer impedance and small polarization degree, which is beneficial to improve the charge-discharge capacity.

[0068] The XRD pattern of the K 0.5 Mn 0.95 Cu 0.05 O2 product prepared in this example is shown in Figure 1 The XRD image shows that the K 0.5 Mn 0.95 Cu0.05 O2 is also a P3 phase layered material without any impurities, belonging to the R-3m space group (PDF #30-0950).

[0069] The K 0.5 Mn 0.95 Cu 0.05 The rate performance of the K Figure 6 As shown in FIG. 2B, when the current density gradually increased from 50 mA / g to 100, 200, 500, 1000 and then returned to 100 mA / g, the specific capacity was 95.7, 84.6, 73.5, 60.3, 45.6, 82.7 mAh / g, respectively, showing poor rate performance. The K 0.5 Mn 0.95 Cu 0.05 The cycle performance of the K Figure 7 As shown in FIG. 2C, the capacity retention rate rapidly decayed to 68.2% after 100 cycles, proving poor cycle performance. The K 0.5 Mn 0.95 Cu 0.05 The electrochemical impedance diagram of the K

[0070] In summary, the preparation of the copper-doped binary manganese-based layered oxide positive electrode material has the characteristics of simplicity, cost and large-scale production. The prepared copper-doped binary manganese-based layered oxide positive electrode material has a highly ordered layered structure, an increased average valence of Mn and a larger interlayer spacing, which suppresses the Jahn-Teller effect, promotes the diffusion ability of potassium ions and enhances the structural stability, and is one of the candidates for the next generation of high specific capacity, fast charging and long life potassium ion battery positive electrode materials. In general, the application provides a preparation method and application of a copper-doped binary manganese-based layered oxide positive electrode material. Copper salt is used as a dopant, and a sol-gel method is used to dope copper elements into manganese-based oxides to obtain a precursor solution, and then high-temperature heat treatment is performed to obtain a copper-doped binary manganese-based layered oxide positive electrode material. The preparation process is as follows: (1) adding various potassium salts, manganese salts, copper salts and binders in deionized water, and stirring until completely dissolved to obtain a precursor; (2) drying the solution obtained in (1); (3) grinding the fluffy solid after drying in (2) into fine particles; (4) high-temperature calcining the fine particles obtained in (3) to obtain a copper-doped binary manganese-based layered oxide positive electrode material powder. The application has the characteristics of simple process, low cost and large-scale production, and the binary manganese-based positive electrode material modified by copper doping has high specific capacity, good cycle stability and excellent rate performance as a positive electrode of a potassium ion battery.

Claims

1. A method for preparing a copper-doped binary manganese-based layered oxide cathode material, characterized in that, The method comprises the following steps: (1) adding various potassium salts, manganese salts, copper salts, binders and acids into deionized water to stir until completely dissolved to obtain a precursor; (2) drying the solution obtained in step (1); (3) grinding the fluffy solid after drying in step (2) into fine particles; (4) high-temperature calcining the fine particles obtained in step (3) to obtain a copper-doped binary manganese-based layered oxide positive electrode material; in step (1), the potassium salt is potassium nitrate, the manganese salt is manganese acetate tetrahydrate, the copper salt is copper acetate monohydrate, the binder is polyvinylpyrrolidone, and the acid is oxalic acid; in step (1), the amount of potassium salt is 5% more than the calculated amount, and the polyvinylpyrrolidone is added in batches between the addition of various materials; in step (1), the synthesis process is heated and stirred in a water bath, the stirring speed is 400-600 r / min, the heating temperature is 60-80 ℃, and the duration is 5-6 h; in step (3), the drying temperature is 110-140 ℃, and the drying time is 10-13 h; in step (4), the calcination atmosphere is air, the precalcination temperature is 490-500 ℃, the heating rate is 5-6 ℃ / min, the calcination time is 2-3 h, then the final calcination temperature is 900-920 ℃, the heating rate is 5-6 ℃ / min, and the calcination time is 12-14 h; after the precalcination in step (4) is completed, the material is ground once, and the final calcination is cooled to 150-200 ℃ and then quickly transferred to a glove box for storage. After the precalcination in step (4) is completed, the material is ground once, and the final calcination is cooled to 150-200 ℃ and then quickly transferred to a glove box for storage. ​ 2. The method for preparing the copper-doped binary manganese-based substrate oxide cathode material according to claim 1, characterized in that, ​

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