Sodium ion layered positive electrode material with composite structure and preparation method and application of sodium ion layered positive electrode material

Abstract

The invention discloses a sodium ion layered positive electrode material with a composite structure as well as a preparation method and application thereof, and relates to the technical field of batteries, the chemical formula of the sodium ion layered positive electrode material with the composite structure is Na < x > Ni < 0.3 > Mn < 0.5 > M < 0.2-y > B < y > O < 2 >, according to the preparation method, the property that an O3 type material is spontaneously unstable to water is utilized, the O3 type material is immediately put into deionized water at 0-100 DEG C for quenching after primary calcination, the loss activity of sodium ions at an interface is improved, alkali metal ions are driven to be rearranged through secondary calcination at high temperature after drying heat treatment again, and a composite structure is spontaneously formed; and meanwhile, internal stress generated by quenching is released, so that the prepared sodium ion layered positive electrode material with the composite structure has a P2 phase and an O3 phase and has layered morphology. The pain point faced by the existing transition metal oxide positive electrode material is solved by utilizing the synergistic effect of different phases, and the high-performance electrode material meeting the actual demand is developed.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and more specifically, to a composite sodium-ion layered cathode material, its preparation method, and its application. Background Technology

[0002] With the continued growth of global energy demand and the overconsumption of traditional fossil fuels, the development of new clean energy sources has become an urgent priority. As a crucial component of the clean energy system, grid-connected energy storage systems can effectively compensate for the intermittent and fluctuating nature of renewable energy sources such as wind and solar power, achieving continuous, controllable, and efficient energy output. Therefore, developing high-performance secondary battery systems suitable for grid-connected energy storage is of great significance for achieving energy structure transformation and ensuring energy security. An ideal energy storage battery system should simultaneously possess characteristics such as abundant resources, low cost, environmental friendliness, and safety and reliability, while also considering high energy density and power density. Against this backdrop, sodium-ion batteries have attracted considerable attention due to the abundance and wide distribution of sodium resources, low cost, and electrochemical characteristics similar to lithium-ion batteries. Compared to lithium-ion batteries, sodium-ion batteries not only have significant advantages in resource acquisition and cost control but also demonstrate potential advantages in safety and cycle life, thus being considered an important candidate for next-generation large-scale grid-connected energy storage technology.

[0003] In sodium-ion battery systems, the cathode material is the core factor determining its energy density, rate performance, and cycle stability. Layered transition metal oxides (NaTMO2, where TM represents a transition metal element) are favored due to their simple preparation methods, high specific capacity, environmental friendliness, and similar production processes to industrialized lithium ternary materials (NCM), and are considered one of the most promising cathode materials. Based on structural type, NaTMO2 is mainly divided into two categories: P2-type and O3-type. P2-type materials exhibit simpler structural transitions, superior diffusion kinetics, and better cycle stability. However, in full-cell systems, the inherent sodium defect characteristics of P2-type materials lead to lower energy density. Conversely, while O3-type materials have poorer sodium ion migration kinetics, they possess higher specific capacity and sodium ion content than P2-type materials, making them more suitable for practical applications. However, both P2-type and O3-type materials are still prone to structural degradation and irreversible phase transitions under long-term cycling and high-voltage conditions, resulting in significant degradation of electrochemical performance. Current modification strategies mainly focus on elemental doping and composite structure design. Elemental doping often introduces multiple cations and anions such as W, Co, Mo, Ru, and F to enhance structural stability. However, these elements often do not participate in redox reactions, reducing the theoretical specific capacity of the material. Moreover, some elements are expensive, leading to increased costs. Furthermore, achieving uniform doping requires extremely precise synthesis conditions. The synthesis process of composite structure design is limited by various factors such as cation potential, reaction temperature, and calcination time, making it difficult to control and resulting in poor reproducibility. The performance advantages are difficult to consistently demonstrate in actual preparation processes. Therefore, existing NaTMO2 materials still suffer from limitations such as high cost, capacity reduction, and difficulty in structural control during modification, severely restricting their application prospects in large-scale energy storage. Summary of the Invention

[0004] The purpose of this invention is to overcome the aforementioned defects in existing technologies and provide a composite sodium-ion layered cathode material, its preparation method, and its applications. Utilizing the spontaneous water instability of O3-type materials, the material is quenched immediately after a single calcination in deionized water at 0°C–100°C to enhance the sodium ion loss activity at the interface. Following a second drying heat treatment, a secondary high-temperature calcination drives the alkali metal ions to rearrange themselves, spontaneously forming a composite structure. Simultaneously, the internal stress generated during quenching is released, thereby stabilizing the composite structure. By leveraging the synergistic effect between different phases, the invention addresses the pain points of existing transition metal oxide cathode materials, developing a high-performance electrode material that meets practical needs.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing a composite structure sodium ion layered cathode material, wherein the chemical formula of the composite structure sodium ion layered cathode material is Na. x Ni0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85≤x≤1, 0<y<0.2; M is selected from at least one lanthanide metal element from La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; B is a combination of at least one main group metal element and at least one transition metal element; the transition metal element is selected from at least one element from Cr, Cu, Fe, Mo, Nb, Ta, Ti, V, W, Y, Zn and Zr; the main group metal element is selected from at least one element from Ba, Sr, Sb, Ca, Mg, Al, Sn and Bi; the molar ratio of the main group metal element to the transition metal element is 1:1; The preparation method of the composite structure sodium ion layered cathode material includes the following steps: S1. According to the chemical ratio, Na source, Ni source, Mn source, M source and B source are mixed and then ground to obtain a mixture powder; S2. The mixture powder is calcined once at a temperature of 800℃~1300℃ for a time of 6h~36h and at a heating rate of 0.5℃ / min~10℃ / min to obtain precursor A. S3. After the first calcination, the precursor A obtained is immediately placed in deionized water at 0°C~100°C for 1min~15min to quench it, and the precursor B is obtained. S4. The precursor B is subjected to a drying heat treatment at a temperature of 50°C to 180°C for a time of 3 hours to 24 hours to obtain the precursor C. S5. The precursor C is subjected to a second calcination at a temperature of 400℃~700℃ for a time of 0.5h~18h and a heating rate of 0.5℃ / min~10℃ / min to obtain a composite structure sodium ion layered cathode material. The composite sodium ion layered cathode material has a P2 phase and an O3 phase, and has a layered morphology.

[0006] Optionally, the chemical formula of the composite structure sodium ion layered cathode material is Na. x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85≤x≤1, 0<y<0.2; M is selected from at least one lanthanide metal element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; B is selected from equimolar amounts of Ta, Fe, Mg and Sb.

[0007] Optionally, the chemical formula of the composite structure sodium ion layered cathode material is Na. x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85≤x≤1, 0<y<0.2; M is selected from at least one lanthanide metal element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; B is selected from equimolar amounts of Ta, Fe, Mg and Sn.

[0008] Optionally, the chemical formula of the composite structure sodium ion layered cathode material is Na. x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85≤x≤1, 0<y<0.2; M is selected from at least one lanthanide metal element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; B is selected from equimolar amounts of Ta, Fe, Mg and Ca.

[0009] Optionally, the chemical formula of the composite structure sodium ion layered cathode material is Na. x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85≤x≤1, 0<y<0.2; M is selected from at least one lanthanide metal element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; B is selected from Cu, Ti, Mg and Ca in equimolar amounts.

[0010] Optionally, the chemical formula of the composite structure sodium ion layered cathode material is Na. x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85≤x≤1, 0<y<0.2; M is selected from at least one lanthanide metal element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; B is selected from equimolar amounts of Cu, Zn, Mg and Al.

[0011] Optionally, in step S5, the temperature of the secondary calcination is 450℃~550℃, and the time of the secondary calcination is 3h~5h; in step S3, the temperature of the quenching is 10℃~80℃, and the time of the quenching is 1min~15min; in step S4, the temperature of the drying heat treatment is 70℃~120℃, and the holding time is 6h~15h.

[0012] Optionally, in step S1, the grinding is ball milling; the ball milling time is 1h to 24h, and the ball milling speed is 300rpm to 1200rpm; preferably, the ball milling time is 3h to 12h, and the ball milling speed is 400rpm to 800rpm.

[0013] Optionally, in step S1, the particle size of the mixture powder is 500 nm to 1 μm; the Na source is Na2CO3; and the Ni source, the Mn source, the M source, and the B source are at least one of their respective metal carbonates and oxides.

[0014] The present invention also discloses a composite sodium ion layered cathode material prepared by the preparation method described above.

[0015] The present invention also discloses the application of a composite structure sodium ion layered cathode material prepared by the above preparation method in sodium ion battery cathode materials.

[0016] Implementing the embodiments of the present invention will have the following beneficial effects: This invention provides a general method for synthesizing multiphase layered metal oxides, characterized by its simplicity, ease of implementation, readily available and inexpensive raw materials. Utilizing the intrinsic instability of O3-type materials in water, the material is immediately quenched in low-temperature deionized water after a single high-temperature calcination. The synergistic effect of the intense thermal shock and water molecule erosion during quenching significantly enhances the dissolution activity of sodium ions at the interface and generates controllable internal stress, providing a strong driving force and predetermined nucleation sites for subsequent phase restructuring. The subsequent secondary calcination process, while driving the rearrangement of alkali metal ions at high temperature and spontaneously forming an O3 / P2 multiphase composite structure, effectively releases the internal stress generated by quenching, ensuring the integrity and thermodynamic stability of the final product's layered structure. Furthermore, the physical properties of the material and the ratio between multiphase structures can be adjusted through the selection of raw materials, changes in calcination temperature and time, and storage time in aqueous solution, offering flexible and diverse methods. This invention offers good controllability and high flexibility in the composition of the cathode material for composite sodium-ion batteries. The sodium-ion batteries assembled using the layered transition metal oxide as the cathode material exhibit high sodium storage capacity, excellent stability and rate performance, and are a very green, safe and inexpensive electrochemical energy storage system. Therefore, the sodium-ion battery of this invention is expected to serve as a new type of high-energy-density energy storage device and has good application prospects. Attached Figure Description

[0017] Figure 1 The X-ray diffraction results of the powder in Example 1 of this invention are shown. By comparing it with the standard P2 phase and O3 phase cards, it can be clearly seen that it has characteristic peaks of both phases.

[0018] Figure 2 The image shown is a high-resolution transmission electron microscope image of the powder in Example 1 of the present invention. It can be seen that Example 1 has a layered structure. At the same time, the difference in atomic arrangement also shows that it contains both phase and O3 phase.

[0019] Figure 3 The energy dispersive X-ray spectrum of the powder in Example 1 of this invention shows that the elemental distribution remains uniform after quenching and reheating, with no obvious elemental segregation. Detailed Implementation The present invention will be further described below with reference to specific embodiments, but this does not limit the present invention in any way.

[0020] Example 1 The chemical formula of the composite sodium ion layered cathode material in this embodiment is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.0125 Fe 0.0125 Mg 0.0125 Sb 0.0125 O2.

[0021] The preparation method of composite structure sodium ion layered cathode material includes the following steps: S1. According to the chemical ratio, Na2CO3, Ni2CO3, Mn2CO3, La2O3, Ta2O5, Fe2O3, MgO and Sb2O3 are mixed and then ball-milled for 6 hours at a speed of 800 rpm to obtain a mixed powder with a particle size of 700 nm.

[0022] S2. The mixture powder is calcined once at a temperature of 950℃ for 15 hours at a heating rate of 5℃ / min to obtain precursor A.

[0023] S3. After the first calcination, the precursor A was immediately placed in deionized water at 25°C for 3 minutes to quench it, thus obtaining precursor B.

[0024] S4. Precursor B is subjected to drying heat treatment at a temperature of 80℃ for 8 hours to obtain precursor C.

[0025] S5. The precursor C is subjected to a second calcination at a temperature of 500℃ for 5 hours and a heating rate of 5℃ / min to obtain a composite sodium ion layered cathode material with a particle size of 3µm. The composite sodium ion layered cathode material has a P2 phase and an O3 phase and a layered morphology, denoted as A-1.

[0026] Example 2 The only difference between this embodiment and Example 1 is that B is selected from equimolar amounts of Ta and Sb, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.025 Sb 0.025 O2, denoted as A-2.

[0027] Example 3 The only difference between this embodiment and Example 1 is that B is selected from equimolar amounts of Ta and Mg, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.025 Mg 0.025 O2, denoted as A-3.

[0028] Example 4 The only difference between this embodiment and Example 1 is that B is selected from equimolar amounts of Fe and Mg, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Fe 0.025 Mg 0.025 O2, denoted as A-4.

[0029] Example 5 The only difference between this embodiment and Example 1 is that B is selected from equimolar amounts of Fe and Sb, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Fe 0.025 Sb 0.025 O2, denoted as A-5.

[0030] Example 6 The only difference between this embodiment and Example 1 is that the molar ratio of Ta, Fe, Mg, and Sb is 3:2:3:2, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.015 Fe 0.01 Mg 0.015 Sb 0.01 O2, denoted as A-6.

[0031] Example 7 The only difference between this embodiment and Example 1 is that M is selected from Ce, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 Ce 0.15 Ta0.0125 Fe 0.0125 Mg 0.0125 Sb 0.0125 O2, denoted as A-7.

[0032] Example 8 The only difference between this embodiment and Embodiment 1 is that the y value is 0.02 (less than that in Embodiment 1), and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.18 Ta 0.01 Fe 0.01 Mg 0.01 Sb 0.01 O2, denoted as A-8.

[0033] Example 9 The only difference between this embodiment and Example 1 is that the y value is 0.08 (greater than in Example 1), and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.12 Ta 0.02 Fe 0.02 Mg 0.02 Sb 0.02 O2, denoted as A-9.

[0034] Example 10 The only difference between this embodiment and Example 1 is that B is selected from Fe, Mg, and Sb, wherein the molar ratio of Fe, Mg, and Sb is 2:1:1, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Fe 0.025 Mg 0.0125 Sb 0.0125 O2, denoted as A-10.

[0035] Comparative Example 1 The only difference between this comparative example and Example 1 is that the molar ratio of Ta, Fe, Mg, and Sb is 2:2:3:3, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.01 Fe 0.01 Mg 0.015 Sb 0.015 O2, denoted as B-1.

[0036] Comparative Example 2 The only difference between this comparative example and Example 1 is that the molar ratio of Ta, Fe, Mg, and Sb is 3:3:2:2, and the resulting cathode material has the chemical formula NaNi.0.3 Mn 0.5 La 0.05 Ta 0.015 Fe 0.015 Mg 0.005 Sb 0.005 O2, denoted as B-2.

[0037] Comparative Example 3 The only difference between this embodiment and Embodiment 1 is that the addition of La element is omitted, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 Ta 0.05 Fe 0.05 Mg 0.05 Sb 0.05 O2, denoted as B-3.

[0038] Comparative Example 4 The only difference between this comparative example and Example 1 is that B is selected from equimolar amounts of Ta and Fe, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.025 Fe 0.025 O2, denoted as B-4.

[0039] Comparative Example 5 The only difference between this comparative example and Example 1 is that B is selected from equimolar amounts of Mg and Sb, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Mg 0.025 Sb 0.025 O2, denoted as B-5.

[0040] Comparative Example 6 The only difference between this embodiment and Embodiment 1 is that Fe is replaced with Co. The Co source is cobalt oxide, and the chemical formula of the cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.0125 Co 0.0125 Mg 0.0125 Sb 0.0125 O2, denoted as B-6.

[0041] Example 11 The only difference between this embodiment and Example 1 is that B is selected from equimolar amounts of Ta, Fe, Mg, and Sn. Tin dioxide is used as the Sn source, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15Ta 0.0125 Fe 0.0125 Mg 0.0125 Sn 0.0125 O2, denoted as A-11.

[0042] Example 12 The only difference between this embodiment and Example 11 is that B is selected from equimolar amounts of Ta and Sn, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.025 Sn 0.025 O2, denoted as A-12.

[0043] Example 13 The only difference between this embodiment and Example 11 is that B is selected from equimolar amounts of Fe and Sn, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Fe 0.025 Sn 0.025 O2, denoted as A-13.

[0044] Example 14 The only difference between this embodiment and Example 11 is that the molar ratio of Ta, Fe, Mg, and Sn is 3:2:3:2, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.015 Fe 0.01 Mg 0.015 Sn 0.01 O2, denoted as A-14.

[0045] Example 15 The only difference between this embodiment and Example 11 is that M is selected from Pr, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 Pr 0.15 Ta 0.0125 Fe 0.0125 Mg 0.0125 Sn 0.0125 O2, denoted as A-15.

[0046] Example 16 The only difference between this embodiment and Example 11 is that the y-value is less than that in Example 1, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.18 Ta 0.005 Fe 0.005 Mg0.005 Sn 0.005 O2, denoted as A-16.

[0047] Example 17 The only difference between this embodiment and Example 11 is that the y-value is greater than that in Example 1, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.13 Ta 0.0175 Fe 0.0175 Mg 0.0175 Sn 0.0175 O2, denoted as A-17.

[0048] Example 18 The only difference between this embodiment and Example 11 is that B is selected from Fe, Mg, and Sn, wherein the molar ratio of Fe, Mg, and Sn is 2:1:1, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Fe 0.025 Mg 0.0125 Sn 0.0125 O2, denoted as A-18.

[0049] Comparative Example 7 The only difference between this comparative example and Example 11 is that the molar ratio of Ta, Fe, Mg, and Sn is 2:2:3:3, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.01 Fe 0.01 Mg 0.015 Sn 0.015 O2, denoted as B-7.

[0050] Comparative Example 8 The only difference between this comparative example and Example 11 is that the molar ratio of Ta, Fe, Mg, and Sn is 3:3:2:2, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.015 Fe 0.015 Mg 0.01 Sn 0.01 O2, denoted as B-8.

[0051] Comparative Example 9 The only difference between this embodiment and Embodiment 11 is that the addition of La element is omitted, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 Ta0.05 Fe 0.05 Mg 0.05 Sn 0.05 O2, denoted as B-9.

[0052] Comparative Example 10 The only difference between this comparative example and Example 11 is that B is selected from equimolar amounts of Mg and Sn, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Mg 0.025 Sn 0.025 O2, denoted as B-10.

[0053] Comparative Example 11 The only difference between this embodiment and Example 11 is that Fe is replaced with Co. The Co source is cobalt oxide, and the chemical formula of the cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.0125 Co 0.0125 Mg 0.0125 Sn 0.0125 O2, denoted as B-11.

[0054] Example 19 The only difference between this embodiment and Example 1 is that B is selected from equimolar amounts of Ta, Fe, Mg, and Ca. Calcium carbonate is used as the Ca source, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.0125 Fe 0.0125 Mg 0.0125 Ca 0.0125 O2, denoted as A-19.

[0055] Example 20 The only difference between this embodiment and Example 19 is that B is selected from equimolar amounts of Ta and Ca, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.025 Ca 0.025 O2, denoted as A-20.

[0056] Example 21 The only difference between this embodiment and Example 19 is that B is selected from equimolar amounts of Fe and Ca, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Fe 0.025Ca 0.025 O2, denoted as A-21.

[0057] Example 22 The only difference between this embodiment and Example 19 is that the molar ratio of Ta, Fe, Mg, and Ca is 3:2:3:2, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.015 Fe 0.01 Mg 0.015 Ca 0.01 O2, denoted as A-22.

[0058] Example 23 The only difference between this embodiment and Example 19 is that M is selected from Nd, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 Nd 0.15 Ta 0.0125 Fe 0.0125 Mg 0.0125 Ca 0.0125 O2, denoted as A-23.

[0059] Example 24 The only difference between this embodiment and Example 19 is that the y-value is less than that in Example 1, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.18 Ta 0.005 Fe 0.005 Mg 0.005 Ca 0.005 O2, denoted as A-24.

[0060] Example 25 The only difference between this embodiment and Example 19 is that the y-value is greater than that in Example 1, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.13 Ta 0.0175 Fe 0.0175 Mg 0.0175 Ca 0.0175 O2, denoted as A-25.

[0061] Example 26 The only difference between this embodiment and Example 19 is that B is selected from Fe, Mg, and Ca, wherein the molar ratio of Fe, Mg, and Ca is 2:1:1, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Fe0.025 Mg 0.0125 Ca 0.0125 O2, denoted as A-26.

[0062] Comparative Example 12 The only difference between this comparative example and Example 19 is that the molar ratio of Ta, Fe, Mg, and Ca is 2:2:3:3, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.01 Fe 0.01 Mg 0.015 Ca 0.015 O2, denoted as B-12.

[0063] Comparative Example 13 The only difference between this comparative example and Example 19 is that the molar ratio of Ta, Fe, Mg, and Ca is 3:3:2:2, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.015 Fe 0.015 Mg 0.01 Ca 0.01 O2, denoted as B-13.

[0064] Comparative Example 14 The only difference between this embodiment and Example 19 is that the addition of La element is omitted, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 Ta 0.05 Fe 0.055 Mg 0.05 Ca 0.05 O2, denoted as B-14.

[0065] Comparative Example 15 The only difference between this comparative example and Example 19 is that B is selected from equimolar amounts of Mg and Ca, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Mg 0.025 Ca 0.025 O2, denoted as B-15.

[0066] Comparative Example 16 The only difference between this embodiment and Example 19 is that Fe is replaced with Co. The Co source is cobalt oxide, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Ta 0.0125Co 0.0125 Mg 0.0125 Ca 0.0125 O2, denoted as B-16.

[0067] Example 27 The only difference between this embodiment and Example 1 is that B is selected from equimolar amounts of Cu, Ti, Mg, and Ca. Calcium carbonate is used as the Ca source, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.0125 Ti 0.0125 Mg 0.0125 Ca 0.0125 O2, denoted as A-27.

[0068] Example 28 The only difference between this embodiment and Example 27 is that B is selected from equimolar amounts of Cu and Mg, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.025 Mg 0.025 O2, denoted as A-28.

[0069] Example 29 The only difference between this embodiment and Embodiment 27 is that B is selected from equimolar amounts of Cu and Ca, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.025 Ca 0.025 O2, denoted as A-29.

[0070] Example 30 The only difference between this embodiment and Example 27 is that B is selected from equimolar amounts of Ti and Mg, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ti 0.025 Mg 0.025 O2, denoted as A-30.

[0071] Example 31 The only difference between this embodiment and Example 27 is that B is selected from equimolar amounts of Ti and Ca, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Ti 0.025 Ca 0.025 O2, denoted as A-31.

[0072] Example 32 The only difference between this embodiment and Example 27 is that the molar ratio of Cu, Ti, Mg, and Ca is 3:2:3:2, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.015 Ti 0.01 Mg 0.015 Ca 0.01 O2, denoted as A-32.

[0073] Example 33 The only difference between this embodiment and Example 27 is that M is selected from Sm, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 Sm 0.15 Cu 0.0125 Ti 0.0125 Mg 0.0125 Ca 0.0125 O2, denoted as A-33.

[0074] Example 34 The only difference between this embodiment and Embodiment 27 is that the y-value is less than that in Embodiment 1, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.18 Cu 0.005 Ti 0.005 Mg 0.005 Ca 0.005 O2, denoted as A-34.

[0075] Example 35 The only difference between this embodiment and Embodiment 27 is that the y-value is greater than that in Embodiment 1, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.13 Cu 0.0175 Ti 0.0175 Mg 0.0175 Ca 0.0175 O2, denoted as A-35.

[0076] Example 36 The only difference between this embodiment and Example 27 is that B is selected from Cu, Ti, and Mg, wherein the molar ratio of Cu, Ti, and Mg is 1:1:2, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.0125 Ti 0.0125 Mg 0.025O2, denoted as A-36.

[0077] Comparative Example 17 The only difference between this comparative example and Example 27 is that the molar ratio of Cu, Ti, Mg, and Ca is 2:2:3:3, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.01 Ti 0.01 Mg 0.015 Ca 0.015 O2, denoted as B-17.

[0078] Comparative Example 18 The only difference between this comparative example and Example 27 is that the molar ratio of Cu, Ti, Mg, and Ca is 3:3:2:2, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.015 Ti 0.015 Mg 0.01 Ca 0.01 O2, denoted as B-18.

[0079] Comparative Example 19 The only difference between this embodiment and Example 27 is that the addition of La element is omitted, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 Cu 0.05 Ti 0.05 Mg 0.05 Ca 0.05 O2, denoted as B-19.

[0080] Comparative Example 20 The only difference between this comparative example and Example 27 is that B is selected from equimolar amounts of Cu and Ti, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.025 Ti 0.025 O2, denoted as B-20.

[0081] Comparative Example 21 The only difference between this comparative example and Example 27 is that B is selected from equimolar amounts of Mg and Ca, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Mg 0.025 Ca 0.025 O2, denoted as B-21.

[0082] Example 37 The only difference between this embodiment and Example 1 is that B is selected from equimolar amounts of Cu, Zn, Mg, and Al. Zinc oxide is used as the Zn source, and aluminum oxide is used as the Al source. The resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.0125 Zn 0.012 5Mg 0.0125 Al 0.0125 O2, denoted as A-37.

[0083] Example 38 The only difference between this embodiment and Example 37 is that B is selected from equimolar amounts of Cu and Al, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.025 Al 0.025 O2, denoted as A-38.

[0084] Example 39 The only difference between this embodiment and Example 37 is that B is selected from equimolar amounts of Zn and Mg, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Zn 0.025 Mg 0.025 O2, denoted as A-39.

[0085] Example 40 The only difference between this embodiment and Example 37 is that B is selected from equimolar amounts of Zn and Al, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Zn 0.025 Al 0.025 O2, denoted as A-40.

[0086] Example 41 The only difference between this embodiment and Example 27 is that the molar ratio of Cu, Zn, Mg, and Al is 3:2:3:2, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.015 Zn 0.01 Mg 0.015 Al 0.01 O2, denoted as A-41.

[0087] Example 42 The only difference between this embodiment and Example 27 is that M is selected from Gd, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 Gd 0.15 Cu 0.0125 Zn 0.0125 Mg 0.0125 Al 0.0125 O2, denoted as A-42.

[0088] Example 43 The only difference between this embodiment and Embodiment 27 is that the y-value is less than that in Embodiment 1, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.18 Cu 0.005 Zn 0.005 Mg 0.005 Al 0.005 O2, denoted as A-43.

[0089] Example 44 The only difference between this embodiment and Embodiment 27 is that the y-value is greater than that in Embodiment 1, and the chemical formula of the obtained cathode material is NaNi. 0.3 Mn 0.5 La 0.13 Cu 0.0175 Zn 0.0175 Mg 0.0175 Al 0.0175 O2, denoted as A-44.

[0090] Example 45 The only difference between this embodiment and Example 27 is that B is selected from Zn, Mg, and Al, wherein the molar ratio of Zn, Mg, and Al is 2:1:1, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Zn 0.025 Mg 0.0125 Al 0.0125 O2, denoted as A-45.

[0091] Comparative Example 22 The only difference between this comparative example and Example 27 is that the molar ratio of Cu, Zn, Mg, and Al is 2:2:3:3, and the chemical formula of the resulting cathode material is NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.01 Zn 0.01 Mg 0.015 Al 0.015 O2, denoted as B-22.

[0092] Comparative Example 23 The only difference between this comparative example and Example 27 is that the molar ratio of Cu, Zn, Mg, and Al is 3:3:2:2, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.015 Zn 0.015 Mg 0.01 Al 0.01 O2, denoted as B-23.

[0093] Comparative Example 24 The only difference between this embodiment and Example 27 is that the addition of La element is omitted, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 Cu 0.05 Zn 0.05 Mg 0.05 Al 0.05 O2, denoted as B-24.

[0094] Comparative Example 25 The only difference between this comparative example and Example 27 is that B is selected from equimolar amounts of Cu and Zn, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Cu 0.025 Zn 0.025 O2, denoted as B-25.

[0095] Comparative Example 26 The only difference between this comparative example and Example 27 is that B is selected from equimolar amounts of Mg and Al, and the resulting cathode material has the chemical formula NaNi. 0.3 Mn 0.5 La 0.15 Mg 0.025 Al 0.025 O2, denoted as B-26.

[0096] Examples 46-48, Comparative Example 27 The only difference between this embodiment and Embodiment 1 is that the secondary calcination temperatures are 450℃, 550℃, 700℃, and 800℃, respectively, and are denoted as A-46, A-47, A-48, and B-27.

[0097] Examples 49-50 The only difference between this embodiment and Embodiment 1 is that the quenching temperatures are 0℃ and 100℃, respectively, and are denoted as A-49 and A-50.

[0098] Comparative Example 28 Compared with Example 1, steps S3 and S4 are omitted in this embodiment. Specifically, after processing according to steps S1 and S2 in Example 1, the obtained precursor A is washed with water at 25°C, then dried at 120°C and subjected to secondary calcination. The secondary calcination and its corresponding parameters are the same as step S5 in Example 1, and are denoted as B-28.

[0099] Test case The material obtained in Example 1 was tested. Figure 1 This is the X-ray diffraction (XRD) pattern of the final product prepared in Example 1 of this invention. By comparing it with the standard P2 phase and O3 phase cards, it can be clearly seen that it has the characteristic peaks of both phases. Figure 2 This is a high-resolution transmission electron microscope image of the powder in Example 1 of the present invention. It can be seen that Example 1 has a layered structure. At the same time, the difference in atomic arrangement also shows that it contains both P2 phase and O3 phase. Figure 3 This is the energy dispersive X-ray spectrum of the powder in Example 1 of the present invention. It can be seen that the elemental distribution remains uniform after quenching and reheating, and no obvious elemental segregation has occurred.

[0100] A-1-A-50 and B-1-B-28, vinylidene fluoride (PVDF), and acetylene black were mixed uniformly at room temperature in a mass ratio of 8:1:1. N-methylpyrrolidone was added to form a slurry, which was then coated onto aluminum foil and vacuum dried to obtain the composite positive electrode. The composite positive electrode prepared above was assembled into a sodium-ion battery with a sodium negative electrode. The electrolyte used was a 1M NaClO4 EC / DEC (volume ratio 1:1) solution. The sodium-ion battery was subjected to constant current charge-discharge tests in the carbonate electrolyte at a rate of 0.1C (equivalent to 15 mA / g) within a voltage range of 1.5–4.5V. Results are shown in Table 1-2.

[0101] Table 1

[0102] Table 2

[0103] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for preparing a composite structure sodium-ion layered cathode material, characterized in that, The chemical formula of the composite structure sodium-ion layered cathode material is Na x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein 0.85≤x≤1, 0 The preparation method of the composite structure sodium ion layered positive electrode material comprises the following steps: S1, according to the chemical ratio, the Na source, the Ni source, the Mn source, the M source and the B source are mixed, then ground to obtain a mixture powder; S2, the mixture powder is once calcined, the temperature of the once calcination is 800-1300℃, the time of the once calcination is 6-36h, the heating rate of the once calcination is 0.5-10℃ / min, to obtain a precursor A; S3, the precursor A obtained after the once calcination is immediately put into deionized water at 0-100℃ for quenching for 1-15min to obtain a precursor B; S4, the precursor B is dried and heat treated, the temperature of the drying and heat treatment is 50-180℃, the time of the drying and heat treatment is 3-24h to obtain a precursor C; S5, the precursor C is twice calcined, the temperature of the twice calcination is 400-700℃, the time of the twice calcination is 0.5-18h, the heating rate of the twice calcination is 0.5-10℃ / min to obtain a composite structure sodium ion layered positive electrode material; The composite structure sodium ion layered positive electrode material has P2 phase and O3 phase and has a layered morphology.

2. The method for preparing the composite structure sodium ion layered cathode material according to claim 1, characterized in that, The chemical formula of the composite structure sodium ion layered cathode material is Na x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85<=x<=1, 0 M is selected from at least one lanthanide metal element in La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; and B is selected from equal molar amounts of Ta, Fe, Mg and Sb.

3. The method for preparing the composite structure sodium ion layered cathode material according to claim 1, characterized in that, The chemical formula of the composite structure sodium ion layered cathode material is Na x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85≤x≤1, 0 A lanthanide metal element selected from at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; and B is selected from equimolar amounts of Ta, Fe, Mg and Sn.

4. The method for preparing the composite structure sodium ion layered cathode material according to claim 1, characterized in that, The chemical formula of the composite structure sodium ion layered cathode material is Na x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85<=x<=1, 0 M is selected from at least one lanthanide metal element in La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; and B is selected from equal molar amounts of Ta, Fe, Mg and Ca.

5. The method for preparing the composite structure sodium ion layered cathode material according to claim 1, characterized in that, The chemical formula of the composite structure sodium ion layered cathode material is Na x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85≤x≤1, 0 A lanthanide metal element selected from at least one of La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; and B is selected from equal molar amounts of Cu, Ti, Mg and Ca.

6. The method for preparing the composite structure sodium ion layered cathode material according to claim 1, characterized in that, The chemical formula of the composite structure sodium ion layered cathode material is Na x Ni 0.3 Mn 0.5 M 0.2-y B y O2; wherein, 0.85<=x<=1, 0 M is selected from at least one lanthanide metal element in La, Ce, Pr, Nd, Sm, Eu, Gd, Er, Yb and Lu; and B is selected from equal molar amounts of Cu, Zn, Mg and Al.

7. The method for preparing the composite structure sodium ion layered cathode material according to claim 1, characterized in that, In step S5, the temperature of the twice calcination is 450-550℃, the time of the twice calcination is 3-5h; in step S3, the quenching temperature is 10-80℃, the quenching time is 1-15min; in step S4, the drying and heat treatment temperature is 70-120℃, the holding time is 6-15h.

8. The method for preparing the composite structure sodium ion layered cathode material according to claim 1, characterized in that, In step S1, the grinding is ball milling, the ball milling time is 1-24h, the ball milling speed is 300-1200rpm; The particle size of the mixture powder is 500nm-1μm; The Na source is Na2CO3; The Ni source, the Mn source, the M source and the B source are at least one of the corresponding metal carbonates and oxides respectively.

9. A composite structure sodium ion layered positive electrode material prepared by the preparation method in any one of claims 1-8.

10. Application of a composite structure sodium ion layered positive electrode material prepared by the preparation method in any one of claims 1-8 in a sodium ion battery positive electrode material.

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