A P2 / O3 biphasic composite material, its preparation method and application, and a sodium-ion battery

Abstract

The present invention provides a P2 / O3 biphasic composite material, a preparation method and application thereof, and a sodium ion battery, belonging to the technical field of electrode materials. The P2 / O3 biphasic composite material provided by the present invention comprises a P2 phase and an O3 phase; the composition of the P2 phase is Na x MnO2, where 0.45 ≤ x ≤ 0.7; the composition of the O3 phase is Na y Ni a Cu b Fe c Mn d O2, where 0.75 ≤ y ≤ 1, 0 ≤ a < 0.3, 0 ≤ b ≤ 0.35, 0 ≤ c ≤ 0.35, 0.1 ≤ d ≤ 0.6; a, b, and c are not simultaneously 0, and a + b + c + d = 1. The P2 / O3 biphasic composite material provided by the present invention has a high discharge capacity and good cycle stability. When the P2 / O3 biphasic composite material is used as a positive electrode material in a sodium ion battery, the cost can be effectively reduced on the basis of improving the electrochemical performance of the sodium ion battery.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and particularly relates to a P2 / O3 biphasic composite material, a preparation method and application thereof, and a sodium ion battery. Background Art

[0002] Sodium ion batteries have the advantages of abundant sodium resources, low cost, and a charge-discharge mechanism similar to that of lithium ion batteries, and are potential substitutes for lithium ion batteries.

[0003] In sodium ion batteries, the positive electrode material is an important factor restricting performance indicators such as the capacity, energy density, and safety of sodium ion batteries. Among the many positive electrode materials for sodium ion batteries, layered positive electrode materials have received wide attention due to their good electrochemical reversibility, high theoretical capacity, and easy synthesis.

[0004] According to the different sodium ion coordination environments, layered positive electrode materials are mainly divided into P2 type and O3 type. Among them, the P2 type is a sodium-deficient compound with open prismatic channels, which can achieve rapid ion deintercalation and insertion, and has good structural stability, but its capacity is relatively low; while the O3 type has the advantage of high specific capacity, but its structural stability is poor, resulting in poor cycle stability. Therefore, the current research direction in this field is to synthesize a P2 / O3 composite phase to integrate the advantages of the P2 and O3 phases, and then synthesize a new type of sodium ion battery positive electrode material. However, the currently developed new type of sodium ion battery positive electrode material with a P2 / O3 composite phase often has poor cycle stability. Summary of the Invention

[0005] The purpose of the present invention is to provide a P2 / O3 biphasic composite material, a preparation method and application thereof, and a sodium ion battery. The P2 / O3 biphasic composite material provided by the present invention has good cycle stability on the basis of having a high discharge capacity.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a P2 / O3 biphasic composite material, including a P2 phase and an O3 phase;

[0008] The composition of the P2 phase is Na x MnO2, where 0.45 ≤ x ≤ 0.7;

[0009] The composition of the O3 phase is Na y Ni a Cu b Fe c Mn dO2, where 0.75 ≤ y ≤ 1, 0 ≤ a < 0.3, 0 ≤ b ≤ 0.35, 0 ≤ c ≤ 0.35, 0.1 ≤ d ≤ 0.6; a, b, and c are not all 0, and a + b + c + d = 1.

[0010] Preferably, the total proportion of the P2 phase and the O3 phase in the P2 / O3 biphasic composite material is 100%.

[0011] Preferably, the phase ratio of the P2 phase to the O3 phase is 1:1, 2:1, 3:1, or 4:1.

[0012] Preferably, the space group of the P2 phase is P63 / mmc; the space group of the O3 phase is R-3m.

[0013] The present invention provides a preparation method of the P2 / O3 biphasic composite material described in the above technical solution, including the following steps:

[0014] The P2 / O3 biphasic composite material is prepared according to the composition of the P2 / O3 biphasic composite material.

[0015] Preferably, the preparation method of the P2 / O3 biphasic composite material includes the following steps:

[0016] Provide a precursor; the composition of the precursor is Ni a Cu b Fe c Mn d (OH)2, and the molar ratio of Ni, Cu, Fe, and Mn in the precursor is the same as the molar ratio of Ni, Cu, Fe, and Mn in the O3 phase;

[0017] Mix the precursor with a sodium source and perform a first calcination to obtain a first material;

[0018] Mix the first material with a manganese source and perform a second calcination to obtain the P2 / O3 biphasic composite material.

[0019] Preferably, the sodium source includes at least one of sodium carbonate, sodium bicarbonate, and sodium hydroxide; the manganese source includes at least one of manganese acetate, manganese carbonate, manganese nitrate, manganese dioxide, and manganese sesquioxide.

[0020] Preferably, the temperature of the first calcination is 300~650 °C, the heat preservation time is 1~5 h, and the heating rate to the temperature of the first calcination is 1~5 °C / min;

[0021] The temperature of the second calcination is 700~950 °C, the heat preservation time is 8~24 h, and the heating rate to the temperature of the second calcination is 1~5 °C / min.

[0022] The present invention provides an application of a P2 / O3 biphasic composite material in a sodium-ion battery, where the P2 / O3 biphasic composite material serves as the cathode material of the sodium-ion battery; the P2 / O3 biphasic composite material is the P2 / O3 biphasic composite material described in the above technical solution or the P2 / O3 biphasic composite material obtained by the preparation method described in the above technical solution.

[0023] The present invention provides a sodium-ion battery, where the cathode material of the sodium-ion battery is the P2 / O3 biphasic composite material described in the above technical solution or the P2 / O3 biphasic composite material obtained by the preparation method described in the above technical solution.

[0024] The present invention provides a P2 / O3 biphasic composite material, including a P2 phase and an O3 phase; the composition of the P2 phase is Na x MnO2, where 0.45 ≤ x ≤ 0.7; the composition of the O3 phase is Na y Ni a Cu b Fe c Mn d O2, where 0.75 ≤ y ≤ 1, 0 ≤ a < 0.3, 0 ≤ b ≤ 0.35, 0 ≤ c ≤ 0.35, 0.1 ≤ d ≤ 0.6; a, b, and c are not simultaneously 0, and a + b + c + d = 1. By introducing sodium ions into the P2 / O3 biphasic composite material, the present invention realizes the construction of an O3-type structure; at the same time, manganese ions are also introduced into the P2 / O3 biphasic composite material. Manganese ions have a very strong electronegativity, which can enhance the repulsion force between positive and negative ions, thereby gradually forming a P2-type structure with a larger interlayer spacing. The more manganese ions are introduced, the stronger the repulsion force between positive and negative ions in the system, so more P2-type structures can be formed, promoting the improvement of the cycling performance. Therefore, the P2 / O3 biphasic composite material provided by the present invention has a high discharge capacity and good cycling stability.

[0025] The present invention provides a preparation method of the P2 / O3 biphasic composite material described in the above technical solution, and a specific proportion of the P2 / O3 coexisting composite phase can be synthesized according to the required electrochemical performance. Moreover, the preparation method provided by the present invention is simple to operate, the raw materials are rich in sources, and the obtained P2 / O3 biphasic composite material has good electrochemical performance. When the P2 / O3 biphasic composite material prepared by the present invention is used as the cathode material in a sodium-ion battery, the proportion of the composite phase is controllable, the synthesis method is simple, and the cost can be effectively reduced on the basis of improving the electrochemical performance of the sodium-ion battery. Description of the Drawings

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0027] Figure 1 XRD pattern of the P2 / O3 biphasic composite prepared in Example 1;

[0028] Figure 2 SEM image of the P2 / O3 biphasic composite prepared in Example 1;

[0029] Figure 3 XRD pattern of the P2 / O3 biphasic composite prepared in Example 2;

[0030] Figure 4 SEM image of the P2 / O3 biphasic composite prepared in Example 2;

[0031] Figure 5 XRD pattern of the P2 / O3 biphasic composite prepared in Example 3;

[0032] Figure 6 SEM image of the P2 / O3 biphasic composite prepared in Example 3;

[0033] Figure 7 XRD pattern of the P2 / O3 biphasic composite prepared in Example 4;

[0034] Figure 8 SEM image of the P2 / O3 biphasic composite prepared in Example 4;

[0035] Figure 9 XRD pattern of the P2 / O3 biphasic composite prepared in Example 5;

[0036] Figure 10 SEM image of the P2 / O3 biphasic composite prepared in Example 5;

[0037] Figure 11 XRD pattern of the P2 / O3 biphasic composite prepared in Comparative Example 1;

[0038] Figure 12 SEM image of the P2 / O3 biphasic composite prepared in Comparative Example 1;

[0039] Figure 13 Phase ratio diagrams of different ratios of the P2 / O3 biphasic composite prepared in the experimental example. Detailed implementation manners

[0040] The present invention provides a P2 / O3 biphasic composite material, comprising a P2 phase and an O3 phase;

[0041] The composition of the P2 phase is Na x MnO2, where 0.45 ≤ x ≤ 0.7;

[0042] The composition of the O3 phase is Na y Ni a Cu b Fe c Mn d O2, where 0.75 ≤ y ≤ 1, 0 ≤ a < 0.3, 0 ≤ b ≤ 0.35, 0 ≤ c ≤ 0.35, 0.1 ≤ d ≤ 0.6; a, b, and c are not simultaneously 0, and a + b + c + d = 1.

[0043] In the present invention, unless otherwise specified, the raw materials used are commercially available products well-known to those skilled in the art or prepared by methods well-known to those skilled in the art.

[0044] In the present invention, the total proportion of the P2 phase and the O3 phase in the P2 / O3 biphasic composite material can be 100%. In the present invention, the phase ratio of the P2 phase and the O3 phase can be 1:1, 2:1, 3:1, or 4:1.

[0045] In the present invention, the composition of the P2 phase is Na x MnO2. In the Na x MnO2 of the present invention, the value of x is 0.45 ≤ x ≤ 0.7; in specific embodiments of the present invention, the value of x can be 0.55, 0.65, or 0.7. In the present invention, the space group of the P2 phase can be P63 / mmc. In the present invention, the role of the P2 phase is to enhance the cycle stability of the obtained biphasic composite material.

[0046] In the present invention, the composition of the O3 phase is Na y Ni a Cu b Fe c Mn d O2. In the Na y Ni a Cu b Fe c Mn d O2 of the present invention, the value of x is 0.75 ≤ y ≤ 1; in specific embodiments of the present invention, the value of x can be 0.75, 0.8, or 0.85. In the Na y Ni a Cu b Fe c Mn dIn O2, the value of a is 0 ≤ a ≤ 0.35; in a specific embodiment of the present invention, the value of a can be 0.11, 0.23 or 0.33. In the Na of the present invention y Ni a Cu b Fe c Mn d In O2, the value of b is 0 ≤ b ≤ 0.35; in a specific embodiment of the present invention, the value of b can be 0.11, 0.22 or 0.3. In the Na of the present invention y Ni a Cu b Fe c Mn d In O2, the value of c is 0 ≤ c ≤ 0.35; in a specific embodiment of the present invention, the value of c can be 0.11, 0.22 or 0.33. In the Na of the present invention y Ni a Cu b Fe c Mn d In O2, the value of d is 0.1 ≤ d ≤ 0.6; in a specific embodiment of the present invention, the value of d can be 0.33, 0.45 or 0.5. In the present invention, the space group of the O3 phase can be R-3m. In the present invention, the role of the O3 phase is to enhance the discharge capacity of the obtained biphasic composite material.

[0047] The present invention also provides a method for preparing the P2 / O3 biphasic composite material described in the above technical solution, including the following steps:

[0048] Prepare the P2 / O3 biphasic composite material according to the composition of the P2 / O3 biphasic composite material.

[0049] In the present invention, the method for preparing the P2 / O3 biphasic composite material can include the following steps:

[0050] Provide a precursor; the composition of the precursor is Ni a Cu b Fe c Mn d (OH)2, and the molar ratios of Ni, Cu, Fe and Mn in the precursor are the same as the molar ratios of Ni, Cu, Fe and Mn in the O3 phase;

[0051] Mix the precursor with a sodium source and perform a first calcination to obtain a first material;

[0052] Mix the first material with a manganese source and perform a second calcination to obtain the P2 / O3 biphasic composite material.

[0053] In the present invention, the preparation method of the precursor refers to the patent document CN116375111A.

[0054] In the present invention, the sodium source may include at least one of sodium carbonate, sodium bicarbonate, and sodium hydroxide; in a specific embodiment of the present invention, the sodium source may be sodium carbonate, sodium bicarbonate, or sodium hydroxide.

[0055] In the present invention, the manganese source may include at least one of manganese acetate, manganese carbonate, manganese nitrate, manganese dioxide, and manganese sesquioxide. In a specific embodiment of the present invention, the manganese source may be manganese acetate, manganese carbonate, manganese nitrate, manganese dioxide, or manganese sesquioxide.

[0056] In the present invention, the temperature of the first calcination may be 300 - 650 °C, the heat preservation time may be 1 - 5 h, and the heating rate for heating to the temperature of the first calcination may be 1 - 5 °C / min. In a specific embodiment of the present invention, the temperature of the first calcination is 300 °C, 400 °C, 500 °C, 600 °C, or 650 °C; the heat preservation time of the first calcination is 1 h, 2 h, 3 h, 4 h, or 5 h; the heating rate for heating to the temperature of the first calcination is 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, or 5 °C / min.

[0057] In the present invention, the temperature of the second calcination may be 700 - 950 °C, the heat preservation time may be 8 - 24 h, and the heating rate for heating to the temperature of the second calcination may be 1 - 5 °C / min. In a specific embodiment of the present invention, the temperature of the second calcination is 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, or 950 °C; the heat preservation time of the second calcination is 8 h, 12 h, 16 h, 20 h, or 24 h; the heating rate for heating to the temperature of the second calcination is 1 °C / min, 2 °C / min, 3 °C / min, 4 °C / min, or 5 °C / min.

[0058] The present invention also provides an application of a P2 / O3 biphasic composite material in a sodium-ion battery, where the P2 / O3 biphasic composite material is used as the positive electrode material of the sodium-ion battery; the P2 / O3 biphasic composite material is the P2 / O3 biphasic composite material described in the above technical solution or the P2 / O3 biphasic composite material obtained by the preparation method described in the above technical solution.

[0059] The present invention also provides a sodium-ion battery. The positive electrode material of the sodium-ion battery is the P2 / O3 biphasic composite material described in the above technical solution or the P2 / O3 biphasic composite material obtained by the preparation method described in the above technical solution. In the present invention, the sodium-ion battery may further include a negative electrode material and an electrolyte. In the present invention, the composition of the negative electrode material of the sodium-ion battery may be a sodium sheet or hard carbon. In the present invention, the electrolyte of the sodium-ion battery may be a solution containing NaPF6 or a solution containing NaClO4. In the present invention, the sodium-ion battery may further include a separator; the composition of the separator may be glass fiber. In a specific embodiment of the present invention, the sodium-ion battery is a CR2032 button-type half cell, including a positive electrode material, a negative electrode material, an electrolyte, and a separator; the positive electrode material is composed of a P2 / O3 biphasic composite material, conductive carbon black, polyvinylidene fluoride, and N-methylpyrrolidone, and the mass ratio of the P2 / O3 biphasic composite material, conductive carbon black, and polyvinylidene fluoride is 9:0.5:0.5; the negative electrode material is a sodium sheet; the electrolyte is composed of NaClO4 / polycarbonate (i.e., a polycarbonate solution of NaClO4), ethylene carbonate, and dimethyl carbonate, and the volume ratio of NaClO4 / polycarbonate, ethylene carbonate, and dimethyl carbonate is 1:1:1; the separator is composed of glass fiber. The present invention can assemble a positive electrode material, a negative electrode material, an electrolyte, and a separator in an argon atmosphere to obtain a sodium-ion battery.

[0060] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0061] Example 1

[0062] This example provides a preparation method for a P2 / O3 biphasic composite material. Among them, the P2 / O3 biphasic composite material is composed of a P2 phase and an O3 phase. Among them, the composition of the P2 phase is NaMnO2, and the space group is P63 / mmc; the composition of the O3 phase is NaNi 0.22 Cu 0.1 Fe 0.32 Mn 0.36 O2, and the space group is R-3m.

[0063] Prepare a precursor with the composition of NaNi 0.22 Cu 0.1 Fe 0.32 Mn 0.36 (OH)2 according to the coprecipitation method.

[0064] Weigh sodium carbonate and the precursor according to the above molar ratio. Then, put the weighed sodium carbonate, precursor, and ethanol into a mortar and mix them evenly. After drying, put the obtained material into a tube furnace, and increase the temperature uniformly at a rate of 3 °C / min to 600 °C. Then, keep it at 600 °C for 2 h under an air atmosphere. After that, cool the obtained material to room temperature to get the first material.

[0065] Weigh 2% manganese acetate according to the molar ratio, and put the weighed manganese acetate, ethanol, and the first material into a mortar and mix them evenly. After drying, put the obtained material into a tube furnace, and increase the temperature uniformly at a rate of 3 °C / min to 800 °C. Then, keep it at 850 °C for 10 h under an air atmosphere. After that, let the obtained material cool naturally to room temperature in the air to get the P2 / O3 biphasic composite material.

[0066] The XRD pattern of the P2 / O3 biphasic composite material prepared in Example 1 is as Figure 1 shown. It can be seen from Figure 1 that the P2 / O3 biphasic composite material obtained in Example 1 contains P2 phase and O3 phase.

[0067] The SEM image of the P2 / O3 biphasic composite material prepared in Example 1 is as Figure 2 shown. It can be seen from Figure 2 that the P2 / O3 biphasic composite material obtained in Example 1 is a microspherical particle composed of flaky particles, and the flaky structure is not obvious.

[0068] Example 2

[0069] Prepare the P2 / O3 biphasic composite material under the conditions of Example 1, except that the molar amount of manganese acetate is replaced from 2% to 5%.

[0070] The XRD pattern of the P2 / O3 biphasic composite material prepared in Example 2 is as Figure 3 shown. It can be seen from Figure 3 that the P2 / O3 biphasic composite material prepared in Example 2 contains P2 phase and O3 phase.

[0071] The SEM image of the P2 / O3 biphasic composite material prepared in Example 2 is as Figure 4 shown. It can be seen from Figure 4 that the P2 / O3 biphasic composite material prepared in Example 2 is a microspherical particle composed of flaky particles, the flaky structure is not obvious, and some small particles begin to appear around it.

[0072] Example 3

[0073] Prepare the P2 / O3 biphasic composite material under the conditions of Example 1, except that the molar amount of manganese acetate is replaced from 2% to 10%.

[0074] The XRD pattern of the P2 / O3 biphasic composite prepared in Example 3 is as follows Figure 5 shown, and it can be seen from Figure 5 that the P2 / O3 biphasic composite prepared in Example 3 contains the P2 phase and the O3 phase.

[0075] The SEM image of the P2 / O3 biphasic composite prepared in Example 3 is as follows Figure 6 shown, and it can be seen from Figure 6 that the P2 / O3 biphasic composite prepared in Example 3 is a microspherical particle composed of flaky particles, the flaky structure is not obvious, and some fine particles gradually increase around it.

[0076] Example 4

[0077] A P2 / O3 biphasic composite was prepared according to the conditions of Example 1, except that the molar amount of manganese acetate was replaced from 2% to 15%.

[0078] The XRD pattern of the P2 / O3 biphasic composite prepared in Example 4 is as follows Figure 7 shown, and it can be seen from Figure 7 that the P2 / O3 biphasic composite prepared in Example 4 contains the P2 phase and the O3 phase.

[0079] The SEM image of the P2 / O3 biphasic composite prepared in Example 4 is as follows Figure 8 shown, and it can be seen from Figure 8 that the P2 / O3 biphasic composite prepared in Example 4 is a microspherical particle composed of flaky particles, the flaky structure is not obvious, and there are some fine particles around it.

[0080] Example 5

[0081] A P2 / O3 biphasic composite was prepared according to the conditions of Example 1, except that the molar amount of manganese acetate was replaced from 2% to 20%.

[0082] The XRD pattern of the P2 / O3 biphasic composite prepared in Example 5 is as follows Figure 9 shown, and it can be seen from Figure 9 that the P2 / O3 biphasic composite prepared in Example 5 contains the P2 phase and the O3 phase.

[0083] The SEM image of the P2 / O3 biphasic composite prepared in Example 5 is as follows Figure 10 shown, and it can be seen from Figure 10 that the P2 / O3 biphasic composite prepared in Example 5 is a microspherical particle composed of flaky particles, the flaky structure is not obvious, and there are some fine particles around it.

[0084] Combined with Examples 1 to 5, it can be seen that as the Mn content in the P2 / O3 biphasic composite material increases, the particle size of the primary particles in the obtained P2 / O3 biphasic composite material gradually decreases.

[0085] Comparative Example 1

[0086] An electrode material was prepared according to the conditions of Example 1, except that no manganese source was added.

[0087] The XRD pattern of the electrode material prepared in Comparative Example 1 is as Figure 11 shown. It can be seen from Figure 11 that the electrode material prepared in Comparative Example 1 only contains the O3 phase.

[0088] The SEM image of the electrode material prepared in Comparative Example 1 is as Figure 12 shown. It can be seen from Figure 12 that the electrode material prepared in Comparative Example 1 is a microspherical particle composed of flaky particles, the flaky structure is relatively clear, and the particle size of the primary particles is relatively large.

[0089] Test Example 1 XRD Test Analysis

[0090] The P2 / O3 biphasic composite materials obtained in Examples 1 to 5 and the electrode material obtained in Comparative Example 1 were subjected to XRD test analysis, and the test results are as Figure 13 shown.

[0091] It can be seen from Figure 13 that the P2 / O3 biphasic composite materials obtained in Examples 1 to 5 are all of P2 / O3 biphasic structure. By adjusting the element content in the P2 / O3 biphasic composite material, the ratio of the P2 and O3 phases also changes; while the electrode material obtained in Comparative Example 1 without any element change is of O3 phase structure.

[0092] Test Example 2 Electrochemical Performance Test

[0093] (1) Under an inert atmosphere, the P2 / O3 biphasic composite material obtained in Example 1, conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) were added to N-methylpyrrolidone (NMP) in a mass ratio of 9:0.5:0.5 for pulping, and the obtained slurry was coated on an aluminum foil. After vacuum drying, it was cut into a composite material with a diameter of 12 mm (loading about 5 - 10 mg / cm 2 ).

[0094] (2) 1 mol / L sodium perchlorate / polycarbonate (PC), ethylene carbonate (EC), and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1:1 to obtain an electrolyte. Using a glass fiber as a separator and a sodium sheet as the negative electrode material, the composite material obtained in step (1) as the positive electrode material, a CR2032 coin-type half-cell was assembled in an argon glove box.

[0095] (3)Charge-discharge test: The voltage range for charge-discharge of the CR2032 coin-type half-cell is 2.0 - 4.1 V. Before the cycle test, the CR2032 coin-type half-cell is activated twice with a relatively small current density of 15 mA / g (0.1 C), and then cycled at a 1C rate within the voltage range of 2.0 - 4.1 V. All electrochemical performance tests are carried out at room temperature.

[0096] (4)Replace the P2 / O3 biphasic composite material obtained in Example 1 with the P2 / O3 biphasic composite materials obtained in Examples 2 - 5 and the electrode material obtained in Comparative Example 1 respectively, and repeat steps (1), (2), and (3) to complete the electrochemical performance tests of CR2032 coin-type half-cells with different cathode material compositions. The results are shown in Table 1.

[0097] Table 1 Electrochemical performance of CR2032 coin-type half-cells composed of different cathode materials

[0098]

[0099] As can be seen from Table 1, the initial capacity of the CR2032 coin-type half-cell composed of the P2 / O3 biphasic composite structure slightly decreases compared with the O3 single-phase structure material, and the decrease amplitude is within an acceptable range. However, the cycle performance of the CR2032 coin-type half-cell is greatly improved; when the P2 / O3 biphasic ratio is 1:1, the electrical performance of the CR2032 coin-type half-cell composed of the P2 / O3 biphasic composite material reaches the best.

[0100] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A P2 / O3 biphasic composite material, characterized in that, It includes a P2 phase and an O3 phase; The composition of the P2 phase is Na x MnO2, where 0.45 ≤ x ≤ 0.7; The composition of the O3 phase is Na y Ni a Cu b Fe c Mn d O2, where 0.75 ≤ y ≤ 1, 0 < a < 0.3, 0 < b ≤ 0.35, 0 < c ≤ 0.35, 0.1 ≤ d ≤ 0.6; a + b + c + d = 1; The total proportion of the P2 phase and the O3 phase in the P2 / O3 biphasic composite material is 100%; The phase ratio of the P2 phase to the O3 phase is 1:1; The preparation method of the P2 / O3 biphasic composite material includes the following steps: The P2 / O3 biphasic composite material is prepared according to the composition of the P2 / O3 biphasic composite material; Provide a precursor; the composition of the precursor is Ni a Cu b Fe c Mn d (OH)2, and the molar ratio of Ni, Cu, Fe, and Mn in the precursor is the same as the molar ratio of Ni, Cu, Fe, and Mn in the O3 phase; Mix the precursor with a sodium source and perform a first calcination to obtain a first material; Mix the first material with a manganese source and perform a second calcination to obtain the P2 / O3 biphasic composite material; The temperature of the first calcination is 300 - 650 °C, the holding time is 1 - 5 h, and the heating rate to the temperature of the first calcination is 1 - 5 °C / min; The temperature of the second calcination is 700 - 950 °C, the holding time is 8 - 24 h, and the heating rate to the temperature of the second calcination is 1 - 5 °C / min.

2. The P2 / O3 biphasic composite material according to claim 1, wherein The space group of the P2 phase is P63 / mmc; the space group of the O3 phase is R-3m.

3. The preparation method of the P2 / O3 biphasic composite material according to any one of claims 1 to 2, characterized in that, It includes the following steps: The P2 / O3 biphasic composite material is prepared according to the composition of the P2 / O3 biphasic composite material; Provide a precursor; the composition of the precursor is Ni a Cu b Fe c Mn d (OH)2, and the molar ratio of Ni, Cu, Fe, and Mn in the precursor is the same as the molar ratio of Ni, Cu, Fe, and Mn in the O3 phase; Mix the precursor with a sodium source and perform a first calcination to obtain a first material; Mix the first material with a manganese source and perform a second calcination to obtain the P2 / O3 biphasic composite material; The temperature of the first calcination is 300 - 650 °C, the holding time is 1 - 5 h, and the heating rate to the temperature of the first calcination is 1 - 5 °C / min; The temperature of the second calcination is 700 - 950 °C, the holding time is 8 - 24 h, and the heating rate to the temperature of the second calcination is 1 - 5 °C / min.

4. The preparation method according to claim 3, characterized in that, The sodium source includes at least one of sodium carbonate, sodium bicarbonate, and sodium hydroxide; the manganese source includes at least one of manganese acetate, manganese carbonate, manganese nitrate, manganese dioxide, and manganese sesquioxide.

5. Application of a P2 / O3 biphasic composite material in a sodium-ion battery, characterized in that, The P2 / O3 biphasic composite material is used as the positive electrode material of a sodium-ion battery; the P2 / O3 biphasic composite material is the P2 / O3 biphasic composite material according to any one of claims 1 - 2 or the P2 / O3 biphasic composite material obtained by the preparation method according to any one of claims 3 - 4.

6. A sodium-ion battery, characterized in that, The positive electrode material of the sodium-ion battery is the P2 / O3 biphasic composite material according to any one of claims 1 - 2 or the P2 / O3 biphasic composite material obtained by the preparation method according to any one of claims 3 - 4.

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