Anti-perovskite material, preparation method thereof, positive electrode material and sodium ion battery

Abstract

The application provides an inverse perovskite material, a preparation method thereof, a positive electrode material and a sodium ion battery, and belongs to the technical field of electrode materials. The inverse perovskite material has an inverse perovskite structure phase, and a chemical expression formula of the inverse perovskite material is Na x Li y TM z Ch m O n ; wherein 1.5 >= x >= 0.4, 1.6 >= y >= 0.5, 0.8 <= z <= 1.2, 0.8 <= m <= 1.2, and 0.8 <= n <= 1.2; TM is selected from transition metal elements, and Ch is selected from chalcogen elements. The application can improve the first circle discharge specific capacity and the cycle performance of a sodium ion battery prepared by using the inverse perovskite material as a positive electrode material by selecting Na elements, Li elements, transition metal elements, chalcogen elements and oxygen elements and regulating the ratio of the elements.

Description

Technical Field

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

[0002] Lithium-ion batteries have attracted much attention due to their high energy density and long cycle life, and are now widely used in portable electronic devices, electric vehicles, and large-scale energy storage. However, the Earth's lithium reserves are very limited and unevenly distributed in the Earth's crust, leading to a continuous increase in the cost of lithium battery applications.

[0003] Sodium, which belongs to the same group as lithium, has similar physical and chemical properties and is abundant in the Earth's crust. It can greatly reduce the manufacturing cost of batteries and is expected to replace lithium-ion batteries in large-scale energy storage systems and other fields.

[0004] The cathode material is a key component that determines battery performance. However, most sodium-ion batteries currently have low initial discharge specific capacity of cathode materials. Furthermore, due to the large radius of sodium ions, the structure and volume of the cathode material change significantly during charging and discharging, which easily leads to capacity decay and poor cycle performance. Summary of the Invention

[0005] The purpose of this application is to provide an anti-perovskite material and its preparation method, a cathode material, and a sodium-ion battery, which aims to improve the discharge specific capacity of the cathode material of the sodium-ion battery and the cycle performance of the sodium-ion battery.

[0006] Firstly, this application provides an anti-perovskite material having an anti-perovskite structural phase, and the general chemical formula of the anti-perovskite material is Na. x Li y TM z Ch m O n Wherein, 1.5≥x≥0.4, 1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2; TM is selected from transition metal elements, and Ch is selected from chalcogens.

[0007] This application prepares an anti-perovskite material by selecting Na, Li, transition metals, chalcogens and oxygen elements in combination and controlling the ratio between each element. Using this anti-perovskite material as a cathode material can improve the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries prepared using this cathode material.

[0008] In conjunction with the first aspect, in an optional implementation of this application, n is greater than or equal to m.

[0009] The above technical solution can improve the stability of the crystal structure of anti-perovskite materials. Using this anti-perovskite material as a cathode material to prepare sodium-ion batteries can make it easier for larger-radius sodium ions to break the crystal structure of the cathode material during extraction and / or insertion, thereby improving the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries.

[0010] Optionally, the ratio of m to n is 1:(1.00-1.15).

[0011] Optionally, the ratio of m to n is 1:(1.05-1.11).

[0012] In conjunction with the first aspect, in an optional embodiment of this application, TM is selected from at least one of Fe, Co, Mn, Ni, V, Ti, W, Cr and Cu.

[0013] Optionally, TM includes Fe and Mn.

[0014] In conjunction with the first aspect, in an optional implementation of this application, Ch is selected from S.

[0015] Compared to selecting other chalcogen elements besides S, the above technical solution, which uses S as Ch, is beneficial for further improving the first-cycle discharge specific capacity of sodium-ion batteries prepared using this anti-perovskite material as the cathode material.

[0016] In conjunction with the first aspect, in an optional embodiment of this application, the anti-perovskite material is Na. 1.5 Li 0.5 Fe 0.8 Mn 0.2 SO, NaLi 0.75 Fe 0.8 Mn 0.2 S 0.95 O 1.05 NaLi 0.75 Fe 0.8 Mn 0.2 S 0.975 O 1.025 or NaLi 0.75 Fe 0.8 Mn 0.2 SO.

[0017] When the anti-perovskite material is selected from the above materials, using the anti-perovskite material as the cathode material can result in a sodium-ion battery with a high first-cycle discharge specific capacity and good cycle performance.

[0018] Optionally, the anti-perovskite material is NaLi 0.75 Fe 0.8 Mn 0.2 S 0.95O 1.05 .

[0019] Secondly, this application provides a method for preparing the anti-perovskite material provided in the first aspect above, comprising: converting a precursor into an anti-perovskite material by electrochemical ion exchange; wherein the general chemical formula of the anti-perovskite material is Na x Li y TM z Ch m O n The general chemical formula for the precursor is Li a TM z Ch m O n The precursor has an anti-perovskite structure phase; in the general chemical formula of the anti-perovskite material and the general chemical formula of the precursor, 1.5≥x≥0.4, 1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2, a>y, TM is selected from transition metal elements, and Ch is selected from chalcogen elements.

[0020] The above technical solution uses electrochemical ion exchange to transfer the precursor (Li) with an anti-perovskite structure phase. x+y TM z Ch m O n By partially extracting Li and inserting Na into the compound, a substance with the general chemical formula Na can be prepared. x Li y TM z Ch m O n Anti-perovskite materials.

[0021] In conjunction with the second aspect, in an optional embodiment of this application, the method for preparing the precursor includes: sequentially ball milling and heating the mixed raw materials; wherein the raw materials include: Li2O, the element corresponding to TM and the element corresponding to Ch; and the heating temperature is 600-800℃.

[0022] The above technical solution involves heating the ball-milled raw materials (including Li₂O, the element corresponding to TM, and the element corresponding to Ch) at 600-800℃, which allows the precursor to fully form an anti-perovskite structural phase. This is beneficial for improving the quality of the subsequently produced anti-perovskite material, where the general chemical expression formula is Na is... x Li y TM z Ch m O n The proportion of the anti-perovskite structure phase is increased, which is beneficial to improving the first-cycle discharge specific capacity of sodium-ion batteries prepared using this anti-perovskite material as the cathode material.

[0023] Optionally, the method for preparing the precursor further includes: cooling the heated system after heat treatment; the cooling step includes: cooling the heated system to 10-30℃ at a temperature of 50-100℃ / min.

[0024] Thirdly, this application provides a method for preparing the anti-perovskite material provided in the first aspect above, wherein the mixed raw materials are sequentially ball-milled and heated; wherein the raw materials include a sodium source, a lithium source, and a substance containing TM; the sodium source includes at least one of Na2O and Na2Ch; the lithium source includes at least one of Li2O and Li2Ch; the substance containing TM includes at least one of a substance composed of TM and O elements and a substance composed of TM and Ch.

[0025] The above technical solution, through direct ball milling and heat treatment of raw materials (i.e., solid-phase synthesis), can achieve the preparation of Na+ as a chemically expressed general formula. x Li y TM z Ch m O n Anti-perovskite materials.

[0026] Optionally, the ball mill rotates at a speed of 400-800 rpm.

[0027] Optionally, the heat treatment temperature is 400-700℃.

[0028] Optionally, the preparation method of anti-perovskite material further includes: cooling the heated system after heat treatment; the cooling step includes: cooling the heated system to 10-30℃ at a temperature of 50-100℃ / min.

[0029] Optionally, in the general chemical expression formula of anti-perovskite materials, 1.6 ≥ y ≥ 1.2.

[0030] Fourthly, this application provides a cathode material, which includes the anti-perovskite material provided in the first aspect above.

[0031] The cathode material provided in this application adopts the anti-perovskite material provided in the first aspect above, which is beneficial to improving the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries prepared using the cathode material.

[0032] Fifthly, this application provides a sodium-ion battery, which includes the positive electrode material provided in the fourth aspect above.

[0033] The sodium-ion battery provided in this application, by employing the cathode material provided in the fourth aspect above, exhibits superior first-cycle discharge specific capacity and cycle performance. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 The process flow diagram for preparing anti-perovskite materials using electrochemical ion exchange provided in this application is shown.

[0036] Figure 2 The process flow diagram for preparing anti-perovskite materials using solid-phase synthesis provided in this application is shown.

[0037] Figure 3 The image shows the XRD pattern of the anti-perovskite material prepared in Example 2 of this application.

[0038] Figure 4 The image shows the XRD pattern of the anti-perovskite material obtained in Example 20 of this application.

[0039] Figure 5 The image shows the XRD pattern of the anti-perovskite material obtained in Example 21 of this application. Detailed Implementation

[0040] This application provides an anti-perovskite material, which has an anti-perovskite structural phase, and the general chemical formula of the anti-perovskite material is Na. x Li y TM z Ch m O n Wherein, 1.5≥x≥0.4, 1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2; TM is selected from transition metal elements, and Ch is selected from chalcogens.

[0041] This application prepares an anti-perovskite material by selecting Na, Li, transition metals, chalcogens and oxygen elements in combination and controlling the ratio between each element. Using this anti-perovskite material as a cathode material can improve the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries prepared using this cathode material.

[0042] As an example, in the general chemical expression formula of the anti-perovskite material, the value of x can be any point or range between 0.4, 0.5, 0.6, 0.75, 0.85, 1.0, 1.2 and 1.5; the value of y can be any point or range between 0.5, 0.75, 1.0, 1.15, 1.25, 1.4, 1.5 and 1.6; and the values ​​of z, m or n can each independently be any point or range between 0.8, 0.9, 1.0, 1.05, 1.1, 1.15 and 1.2.

[0043] In some feasible embodiments of this application, n is greater than or equal to m, that is, the number of O atoms is greater than or equal to the number of Ch (chalcogenide) atoms; this can improve the stability of the crystal structure of the anti-perovskite material. Using the anti-perovskite material as the cathode material to prepare sodium-ion batteries can make it less likely for larger-radius sodium ions to damage the crystal structure of the cathode material during extraction and / or insertion, thereby improving the first-cycle discharge specific capacity and cycle performance of the sodium-ion battery.

[0044] Furthermore, the ratio of m to n is 1:(1.00-1.15), which can further improve the stability of the crystal structure of the anti-perovskite material, thereby helping to further improve the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries prepared using this anti-perovskite material as the cathode material.

[0045] As an example, in the general chemical expression formula of anti-perovskite materials, the ratio of m to n can be any one of 1:1.00, 1:1.02, 1:1.05, 1:1.07, 1:1.10, 1:1.11, 1:1.12 and 1:1.15 or any range between the two.

[0046] Furthermore, if n is greater than m and the ratio of m to n is 1:(1.05-1.11), the stability of the crystal structure of the anti-perovskite material can be further improved, which in turn is beneficial to further improve the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries prepared using this anti-perovskite material as the cathode material.

[0047] In some feasible embodiments of this application, TM is selected from at least one of Fe, Co, Mn, Ni, V, Ti, W, Cr, and Cu. As an example, TM is selected from Fe and Mn.

[0048] It should be noted that in other feasible implementations, TM can also be selected from other transition metal elements, such as Zn or Sc.

[0049] In some feasible embodiments of this application, Ch is selected from S. Compared to Ch being selected from other chalcogenides besides S, selecting Ch from S is beneficial for further improving the first-cycle discharge specific capacity of sodium-ion batteries prepared using this anti-perovskite material as the cathode material.

[0050] It should be noted that, in other feasible implementations, Ch may also be selected from Se and / or Te.

[0051] In some feasible embodiments of this application, in the general chemical expression formula of the anti-perovskite material, 1.0≥x≥1.5 and 0.8≥y≥0.5; by further adjusting the ratio of Na to Li, the first-cycle discharge specific capacity of sodium-ion batteries prepared using this anti-perovskite material as the cathode material can be further improved.

[0052] In some feasible embodiments of this application, the anti-perovskite material is Na. 1.5 Li 0.5 Fe 0.8 Mn 0.2 SO, NaLi 0.75 Fe 0.8 Mn 0.2 S 0.95 O 1.05 NaLi 0.75 Fe 0.8 Mn 0.2 S 0.975 O 1.025 or NaLi 0.75 Fe 0.8 Mn 0.2 SO.

[0053] When the anti-perovskite material is selected from the above materials, using the anti-perovskite material as the cathode material can result in a sodium-ion battery with a high first-cycle discharge specific capacity and good cycle performance.

[0054] Furthermore, the anti-perovskite material is NaLi 0.75 Fe 0.8 Mn 0.2 S 0.95 O 1.05 Sodium-ion batteries made using this anti-perovskite material as the cathode material can achieve a first-cycle discharge specific capacity of up to 219.8 mAh / g and a capacity retention rate of up to 99.6% after 50 cycles.

[0055] This application provides a method for preparing the aforementioned anti-perovskite material. The method includes: converting the precursor into an anti-perovskite material using electrochemical ion exchange; wherein the general chemical formula of the anti-perovskite material is Na. x Li y TMz Ch m O n The general chemical formula for the precursor is Li a TM z Ch m O n The precursor has an anti-perovskite structure phase; in the general chemical formula of the anti-perovskite material and the general chemical formula of the precursor, 1.5≥x≥0.4, 1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2, a>y, TM is selected from transition metal elements, and Ch is selected from chalcogen elements.

[0056] This application utilizes electrochemical ion exchange to convert a precursor (Li) with an anti-perovskite structure phase into an anti-perovskite phase. a TM z Ch m O n By partially extracting Li and inserting Na into the compound, it is possible to prepare a compound with the general chemical formula Na. x Li y TM z Ch m O n Anti-perovskite materials.

[0057] Figure 1 For a process flow diagram of the preparation of anti-perovskite materials using electrochemical ion exchange provided in this application, please refer to [link / reference needed]. Figure 1 Methods for preparing anti-perovskite materials using electrochemical ion exchange include:

[0058] S110 involves sequentially ball milling and heating the mixed raw materials; the raw materials include Li2O, the element corresponding to TM, and the element corresponding to Ch; the heating temperature is 600-800℃.

[0059] According to the chemical formula of the precursor Li a TM z Ch m O n (1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2, a>y, TM is selected from transition metal elements, and Ch is selected from chalcogenides). The ball-milled raw materials (including Li₂O, the element corresponding to TM, and the element corresponding to Ch) are heated at 600-800℃ to allow the precursor to fully form an anti-perovskite structural phase, which is beneficial for improving the quality of the subsequently obtained anti-perovskite material. The general chemical expression formula is Na. x Li y TM z Ch m O nThe proportion of the anti-perovskite structure phase is increased, which is beneficial to improving the first-cycle discharge specific capacity of sodium-ion batteries prepared using this anti-perovskite material as the cathode material.

[0060] As an example, when the raw material for ball milling includes Li2O, the element corresponding to TM, and the element corresponding to Ch, the temperature of the heat treatment can be any value among 600°C, 650°C, 670°C, 700°C, 720°C, 750°C, 770°C, and 800°C, or a range between any two.

[0061] In some feasible embodiments of this application, the heating time is ≥6h, which helps to ensure that the precursor fully forms the anti-perovskite structure phase, thereby helping to improve the first-cycle discharge specific capacity of sodium-ion batteries prepared using the subsequently prepared anti-perovskite material as the cathode material.

[0062] Furthermore, the heat treatment time is 6-20 hours. As an example, the heat treatment time can be any value among 6 hours, 8 hours, 10 hours, 12 hours, 15 hours, 17 hours, and 20 hours, or a range between any two.

[0063] Furthermore, the heating rate for the heat treatment is 2-6℃ / min.

[0064] As an example, the heating rate of the heat treatment can be any one of 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min, 5℃ / min, 5.5℃ / min, and 6℃ / min, or a range between any two.

[0065] In some feasible embodiments of this application, the ball milling speed is 250-500 rpm and the ball milling time is at least 1 hour; this allows the raw materials to be fully and uniformly mixed, which is beneficial to ensure that the precursor fully forms the anti-perovskite structure phase, and thus helps to improve the first-cycle discharge specific capacity of sodium-ion batteries prepared using the subsequently prepared anti-perovskite material as the cathode material.

[0066] Furthermore, the ball milling time is 1-10 hours.

[0067] As an example, the rotational speed of the ball mill can be any value among 250 rpm, 300 rpm, 350 rpm, 400 rpm, 420 rpm, 450 rpm and 500 rpm or a range between any two; the ball milling time can be any value among 1 h, 2 h, 4 h, 5 h, 7 h, 9 h and 10 h or a range between any two.

[0068] It should be noted that, in other feasible embodiments, the raw materials for ball milling and heat treatment to prepare the precursor can also be selected from "the substance composed of the TM and O elements", "the substance composed of the TM and Ch", or Li2Ch, etc.

[0069] S120, after heat treatment, the system is cooled to obtain the precursor Li. a TM z Ch m O n The cooling process includes: cooling the heated system to 10-30℃ at a rate of 50-100℃ / min, where 1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2, a>y, TM is selected from transition metal elements, and Ch is selected from chalcogen elements.

[0070] Rapid cooling of the heat-treated system can increase the proportion of the precursor forming the anti-perovskite phase, which is beneficial for further improving the quality of the subsequently prepared anti-perovskite material with the general chemical formula Na. x Li y TM z Ch m O n The proportion of the anti-perovskite structure phase is increased, which in turn helps to improve the first-cycle discharge specific capacity of sodium-ion batteries prepared using the subsequently prepared anti-perovskite material as the cathode material.

[0071] As an example, the cooling rate after heat treatment can be any value among 50℃ / min, 55℃ / min, 60℃ / min, 70℃ / min, 75℃ / min, 90℃ / min and 100℃ / min or a range between any two; the temperature to which the cooling drops can be any value among 10℃, 15℃, 20℃, 22℃, 25℃, 27℃ and 30℃ or a range between any two.

[0072] S130, using electrochemical ion exchange, converts the precursor into the anti-perovskite material Na. x Li y TM z Ch m O n Wherein, 1.5≥x≥0.4, 1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2, TM is selected from transition metal elements, and Ch is selected from chalcogens.

[0073] The precursor (Li) with an anti-perovskite structure phase is subjected to electrochemical ion exchange. a TMz Ch m O n By partially extracting Li and inserting Na into the compound, a substance with the general chemical formula Na can be prepared. x Li y TM z Ch m O n Anti-perovskite materials.

[0074] In some feasible embodiments of this application, "electrochemical ion exchange is used to convert the precursor into the anti-perovskite material Na..." x Li y TM z Ch m O n The method includes: using a precursor as the working electrode, a sodium-ion battery is subjected to constant current charging and constant current discharging in sequence. Constant current charging is used to extract some Li from the precursor, and constant current discharging is used to insert Na. In the sodium-ion battery, sodium metal is used as the counter electrode, and a solution containing sodium ions is used as the electrolyte.

[0075] As an example, Li is obtained after constant current charging. y TM z Ch m O n (denoted as intermediate), the constant current charging current is AmA / g, the constant current charging time is B h, and A and B satisfy: A×B=(ay)×M, y is Na x Li y TM z Ch m O n The number of Li atoms in the solution, where a is the number of Li atoms. a TM z Ch m O n The number of Li atoms in the precursor, M is the specific capacity required to remove one lithium atom from the precursor; Na is obtained after constant current discharge. x Li y TM z Ch m O n The constant current discharge current is C mA / g, the constant current discharge time is D h, and C and D satisfy: C × D = x × N, where x is Na. x Li y TM z Ch m O n The number of Na atoms in the intermediate, where N is the specific capacity required to embed one sodium atom in the intermediate.

[0076] Furthermore, the constant current charging or discharging time is ≥4h, which can improve the yield of the prepared anti-perovskite material Na. x Li y TM z Ch m O n The yield.

[0077] This application also provides a method for preparing the above-mentioned anti-perovskite material. The preparation method includes: sequentially ball milling and heating the mixed raw materials; wherein the raw materials include a sodium source, a lithium source, and a substance containing TM; the sodium source includes at least one of Na2O and Na2Ch; the lithium source includes at least one of Li2O and Li2Ch; and the substance containing TM includes at least one of a substance composed of TM and O elements and a substance composed of TM and Ch.

[0078] This application enables the preparation of a substance with the general chemical formula Na by directly using ball milling and heat treatment of the raw materials (i.e., solid-phase synthesis). x Li y TM z Ch m O n Anti-perovskite materials.

[0079] Figure 2 For a process flow diagram of the preparation of anti-perovskite materials using solid-state synthesis provided in this application, please refer to [link / reference needed]. Figure 1 Methods for preparing anti-perovskite materials using solid-state synthesis include:

[0080] S210, the mixed raw materials are sequentially ball-milled and heated; wherein, the raw materials include a sodium source, a lithium source and a substance containing TM; the sodium source includes at least one of Na2O and Na2Ch; the lithium source includes at least one of Li2O and Li2Ch; the substance containing TM includes at least one of a substance composed of TM and O elements and a substance composed of TM and Ch.

[0081] According to the chemical formula of anti-perovskite materials, Na x Li y TM z Ch m O n (1.5≥x≥0.4, 1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2, TM selected from transition metal elements, Ch selected from chalcogenides) Raw materials are prepared, and by ball milling and heat treatment (i.e., solid-state synthesis), the chemical formula Na can be obtained. x Li y TM z Ch mO n Anti-perovskite materials.

[0082] In some feasible embodiments of this application, the ball milling speed is 400-800 rpm and the ball milling time is ≥15h; this allows the raw materials to be fully and uniformly mixed, and is conducive to the full reaction of the mixed raw materials and the formation of an anti-perovskite structural phase.

[0083] Furthermore, the ball milling time is 15-30 hours.

[0084] As an example, the rotational speed of the ball mill can be any value among 400 rpm, 450 rpm, 500 rpm, 550 rpm, 600 rpm, 650 rpm, 700 rpm, 750 rpm, and 800 rpm, or a range between any two; the ball milling time can be any value among 15 h, 17 h, 20 h, 22 h, 25 h, 27 h, and 30 h, or a range between any two.

[0085] In some feasible embodiments of this application, the heat treatment temperature is 400-700℃, which can improve the crystallinity of the reacted system and is beneficial to improving the quality of the anti-perovskite material subsequently prepared, where the chemical expression formula is Na is... x Li y TM z Ch m O n The proportion of the anti-perovskite structure phase is increased, which in turn helps to improve the first-cycle discharge specific capacity of sodium-ion batteries prepared using the subsequently prepared anti-perovskite material as the cathode material.

[0086] Furthermore, the heat treatment time is ≥4h.

[0087] Furthermore, the heat treatment time is 4-15 hours.

[0088] As an example, the temperature of the heat treatment can be any value among 400°C, 450°C, 500°C, 550°C, 600°C, 650°C and 700°C or a range between any two; the time of the heat treatment can be any value among 4h, 5h, 7h, 10h, 12h and 15h or a range between any two.

[0089] Furthermore, the heating rate for the heat treatment is 2-6℃ / min.

[0090] As an example, the heating rate of the heat treatment can be any one of 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min, 5℃ / min, 5.5℃ / min, and 6℃ / min, or a range between any two.

[0091] In some feasible embodiments of this application, when preparing anti-perovskite materials using solid-state synthesis, the general chemical expression formula of the anti-perovskite materials has 1.6 ≥ y ≥ 1.2; this is beneficial to ensure that the general chemical expression formula of the subsequently obtained anti-perovskite materials is Na. x Li y TM z Ch m O n The higher proportion of the anti-perovskite phase in the anti-perovskite material is beneficial for improving the first-cycle discharge specific capacity of sodium-ion batteries when using the subsequently prepared anti-perovskite material as the cathode material. If solid-state synthesis is used to prepare the anti-perovskite material, and y < 1.2, the subsequently prepared anti-perovskite material will have more impurity phases, which will appropriately reduce the first-cycle discharge specific capacity of the subsequently prepared sodium-ion battery.

[0092] S220, after heat treatment, the system after heat treatment is cooled down; the cooling process includes cooling the system after heat treatment to 10-30℃ at a rate of 50-100℃ / min.

[0093] Rapid cooling of the system after heat treatment can improve the yield of the anti-perovskite material with the general chemical formula Na. x Li y TM z Ch m O n The proportion of the anti-perovskite structural phase is increased, which in turn helps to improve the specific capacity of anti-perovskite materials.

[0094] As an example, the cooling rate after heat treatment can be any value among 50℃ / min, 55℃ / min, 60℃ / min, 70℃ / min, 75℃ / min, 90℃ / min and 100℃ / min or a range between any two; the temperature to which the cooling drops can be any value among 10℃, 15℃, 20℃, 22℃, 25℃, 27℃ and 30℃ or a range between any two.

[0095] This application also provides a cathode material, which includes the anti-perovskite material provided above.

[0096] The cathode material provided in this application, by employing the aforementioned anti-perovskite material, is beneficial for improving the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries.

[0097] This application also provides a sodium-ion battery, which includes the positive electrode material provided above.

[0098] The sodium-ion battery provided in this application, due to the use of the aforementioned cathode material, exhibits superior first-cycle discharge specific capacity and cycle performance.

[0099] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0100] Example 1

[0101] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Fe 0.8 Mn 0.2 SO, including the following steps:

[0102] (1) 0.6275 g of Li₂O, 0.8935 g of Fe powder, 0.2198 g of Mn powder and 0.6414 g of S powder were ball-milled at 400 rpm for 6 h; then the ball-milled system was heated to 600 °C at a heating rate of 3 °C / min and held at that temperature for 6 h; then cooled to room temperature in water at 15 °C to obtain the precursor Li₂Fe. 0.8 Mn 0.2 SO.

[0103] (2) A working electrode was formed by mixing 0.9 g of the precursor with 0.1 g of super P. A sodium-ion battery was assembled using a Whatman glass fiber diaphragm and commercial sodium electrolyte NaClO4 (1.0 M in EC:DEC = 1:1 Vol%), with sodium metal as the counter electrode. The battery was charged at a constant current of 22.7 mA / g for 12.5 h to obtain Li. 0.75 Fe 0.8 Mn 0.2 SO; then constant current discharge was performed for 10 hours at a current of 22.7 mA / g to obtain NaLi. 0.75 Fe 0.8 Mn 0.2 SO.

[0104] Example 2

[0105] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 0.85 Li 1.15 Fe 0.8 Mn 0.2SO, the preparation method of which differs from that of Example 1 is as follows: in step (2), the constant current charging time is 8.5 h, to obtain Li 1.15 Fe 0.8 Mn 0.2 SO; the constant current discharge time was 8.5 h, and Na was obtained. 0.85 Li 1.15 Fe 0.8 Mn 0.2 SO.

[0106] Example 3

[0107] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 0.75 Li 1.25 Fe 0.8 Mn 0.2 SO, the preparation method of which differs from that of Example 1 is that in step (2), the constant current charging time is 7.5 h, and Li is obtained. 1.25 Fe 0.8 Mn 0.2 SO; the constant current discharge time was 7.5 h, and Na was obtained. 0.75 Li 1.25 Fe 0.8 Mn 0.2 SO.

[0108] Example 4

[0109] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 0.6 Li 1.4 Fe 0.8 Mn 0.2 SO, the preparation method of which differs from that of Example 1 is as follows: in step (2), the constant current charging time is 6 hours, and Li is obtained. 1.4 Fe 0.8 Mn 0.2 SO; the constant current discharge time was 6 hours, and Na was obtained. 0.6 Li 1.4 Fe 0.8 Mn 0.2 SO.

[0110] Example 5

[0111] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 0.5 Li 1.5 Fe 0.8 Mn 0.2 SO, the preparation method of which differs from that of Example 1 is as follows: in step (2), the constant current charging time is 5 hours, and Li is obtained. 1.5 Fe0.8 Mn 0.2 SO; the constant current discharge time was 5 hours, and Na was obtained. 0.5 Li 1.5 Fe 0.8 Mn 0.2 SO.

[0112] Example 6

[0113] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 0.4 Li 1.6 Fe 0.8 Mn 0.2 SO, the preparation method of which differs from that of Example 1 is as follows: in step (2), the constant current charging time is 4 hours, and Li is obtained. 1.6 Fe 0.8 Mn 0.2 SO; the constant current discharge time was 4 hours, and Na was obtained. 0.4 Li 1.6 Fe 0.8 Mn 0.2 SO.

[0114] Example 7

[0115] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 1.5 Li 0.5 Fe 0.8 Mn 0.2 SO, the preparation method of which differs from that of Example 1 is as follows: in step (2), the constant current charging time is 15 hours, and Li is obtained. 0.5 Fe 0.8 Mn 0.2 SO; the constant current discharge time was 15 h, and Na was obtained. 1.5 Li 0.5 Fe 0.8 Mn 0.2 SO.

[0116] Example 8

[0117] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Fe 0.65 Mn 0.15 SO, the preparation method differs from that in Example 1 in that: in step (1), the masses of Li2O, Fe powder, Mn powder and S powder are 0.6275g, 0.7261g, 0.1648g and 0.6414g respectively, and the obtained precursor is Li2Fe. 0.65 Mn 0.15 SO; In step (2), Li is obtained after constant current charging.0.75 Fe 0.65 Mn 0.15 SO, after constant current discharge, yields NaLi 0.75 Fe 0.65 Mn 0.15 SO.

[0118] Example 9

[0119] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 FeMn 0.2 SO 1.2 The preparation method differs from that in Example 1 in that the masses of Li2O, Fe powder, FeO powder, Mn powder and S powder in step (1) are 0.6275g, 0.8935g, 0.2874g, 0.2198g and 0.6414g, respectively, and the resulting precursor is Li2FeMn. 0.2 SO 1.2 In step (2), Li is obtained after constant current charging. 0.75 FeMn 0.2 SO 1.2 NaLi was obtained after constant current discharge. 0.75 FeMn 0.2 SO 1.2 .

[0120] Example 10

[0121] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Fe 0.8 Mn 0.2 S 0.8 O 1.2 The preparation method differs from that in Example 1 in that the masses of Li2O, Fe powder, FeO powder, Mn powder and S powder in step (1) are 0.6275g, 0.6701g, 0.2874g, 0.2198g and 0.5131g, respectively, and the resulting precursor is Li2Fe 0.8 Mn 0.2 S 0.8 O 1.2 In step (2), Li is obtained after constant current charging. 0.75 Fe 0.8 Mn 0.2 S 0.8 O 1.2 NaLi was obtained after constant current discharge. 0.75 FeMn 0.2 SO 1.2 .

[0122] Example 11

[0123] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Fe 0.8 Mn 0.2 S 1.2 O 0.8 The preparation method differs from that in Example 1 in that the masses of Li2O, Li2S, Fe powder, Mn powder and S powder in step (1) are 0.502g, 0.1838g, 0.8935g, 0.2198g and 0.6414g, respectively, and the resulting precursor is Li2Fe. 0.8 Mn 0.2 S 1.2 O 0.8 In step (2), Li is obtained after constant current charging. 0.75 Fe 0.8 Mn 0.2 S 1.2 O 0.8 NaLi was obtained after constant current discharge. 0.75 Fe 0.8 Mn 0.2 S 1.2 O 0.8 .

[0124] Example 12

[0125] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Fe 0.8 Mn 0.2 S 0.9 O 1.1 The preparation method differs from that in Example 1 in that the masses of Li2O, FeO powder, Fe powder, Mn powder, and S powder in step (1) are 0.6275g, 0.1437g, 0.7818g, 0.2198g, and 0.5773g, respectively, and the resulting precursor is Li2Fe. 0.8 Mn 0.2 S 0.9 O 1.1 In step (2), Li is obtained after constant current charging. 0.75 Fe 0.8 Mn 0.2 S 0.9 O 1.1 NaLi was obtained after constant current discharge. 0.75 Fe 0.8 Mn 0.2 S 0.9 O 1.1 .

[0126] Example 13

[0127] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Fe 0.8 Mn 0.2 S 0.95 O 1.05 The preparation method differs from that in Example 1 in that the masses of Li2O, FeO powder, Fe powder, Mn powder, and S powder in step (1) are 0.6275g, 0.0718g, 0.8377g, 0.2198g, and 0.6093g, respectively, and the resulting precursor is Li2Fe. 0.8 Mn 0.2 S 0.95 O 1.05 In step (2), Li is obtained after constant current charging. 0.75 Fe 0.8 Mn 0.2 S 0.95 O 1.05 NaLi was obtained after constant current discharge. 0.75 Fe 0.8 Mn 0.2 S 0.95 O 1.05 .

[0128] Example 14

[0129] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Fe 0.8 Mn 0.2 S 0.975 O 1.025 The preparation method differs from that in Example 1 in that the masses of Li2O, FeO powder, Fe powder, Mn powder, and S powder in step (1) are 0.6275g, 0.0359g, 0.8656g, 0.2198g, and 0.6254g, respectively, and the resulting precursor is Li2Fe. 0.8 Mn 0.2 S 0.975 O 1.025 In step (2), Li is obtained after constant current charging. 0.75 Fe 0.8 Mn 0.2 S 0.975 O 1.025 NaLi was obtained after constant current discharge. 0.75 Fe 0.8 Mn 0.2 S 0.975 O 1.025 .

[0130] Example 15

[0131] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Co 0.8 Ni 0.2 SO, the preparation method of which differs from that of Example 1 is as follows: the raw materials used in step (1) are 0.6275g of Li2O, 0.9429g of Co powder, 0.2348g of Ni powder and 0.6414g of S powder, respectively, and the resulting precursor is Li2Co. 0.8 Ni 0.2 SO; In step (2), Li is obtained after constant current charging. 0.75 Co 0.8 Ni 0.2 SO, after constant current discharge, yields NaLi 0.75 Co 0.8 Ni 0.2 SO.

[0132] Example 16

[0133] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Fe 0.8 Mn 0.2 The preparation method of SeO differs from that in Example 1 in that 0.6414g of S powder in step (1) is replaced with 1.5792g of Se powder, and the resulting precursor is Li2Fe. 0.8 Mn 0.2 SeO; in step (2), Li is obtained after constant current charging. 0.75 Fe 0.8 Mn 0.2 SeO, after constant current discharge, yields NaLi 0.75 Fe 0.8 Mn 0.2 SeO.

[0134] Example 17

[0135] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is NaLi. 0.75 Fe 0.8 Mn 0.2 SO, the preparation method of which differs from that of Example 1 is that step (1) does not involve the step of "cooling down to room temperature in water at 15°C", and the precursor is obtained by cooling with the furnace after heat preservation (<20°C / min).

[0136] Example 18

[0137] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 0.5 Li 1.5 Fe0.8 Mn 0.2 SO, including the following steps:

[0138] 0.31 g of Na₂O, 0.4706 g of Li₂O, 1.4066 g of FeS and 0.348 g of MnS were ball-milled at 600 rpm for 20 h; then the ball-milled system was heated to 600 °C at a heating rate of 3 °C / min and held at that temperature for 10 h; then cooled to room temperature in water at 15 °C.

[0139] Example 19

[0140] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 0.6 Li 1.4 Fe 0.8 Mn 0.2 SO, the preparation method of which differs from that of Example 18 is that the masses of Na2O, Li2O, FeS and MnS are 0.3719g, 0.4392g, 1.4066g and 0.348g, respectively.

[0141] Example 20

[0142] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 0.75 Li 1.25 Fe 0.8 Mn 0.2 SO, the preparation method of which differs from that of Example 18 is that the masses of Na2O, Li2O, FeS and MnS are 0.4648g, 0.3922g, 1.4066g and 0.348g, respectively.

[0143] Example 21

[0144] This embodiment provides a method for preparing an anti-perovskite material, the chemical formula of which is Na. 0.85 Li 1.15 Fe 0.8 Mn 0.2 SO, the preparation method of which differs from that of Example 18 is that the masses of Na2O, Li2O, FeS and MnS are 0.5268g, 0.3608g, 1.4066g and 0.348g, respectively.

[0145] Comparative Example 1

[0146] This comparative example provides a method for preparing a material with the chemical formula Na. 0.25 Li 1.75 Fe 0.8 Mn 0.2SO, 0.1549 g of Na2O, 0.549 g of Li2O, 1.4066 g of FeS and 0.348 g of MnS were ball-milled at 600 rpm for 20 h; then the ball-milled system was heated to 600 °C at a heating rate of 3 °C / min and held at that temperature for 10 h; then cooled to room temperature in water at 15 °C.

[0147] Comparative Example 2

[0148] This comparative example provides a method for preparing a material with the chemical formula Na. 0.25 Li 1.75 Fe 0.8 Mn 0.2 SO, including the following steps:

[0149] (1) 0.6275 g of Li₂O, 0.8935 g of Fe powder, 0.2198 g of Mn powder and 0.6414 g of S powder were ball-milled at 400 rpm for 6 h; then the ball-milled system was heated to 600 °C at a heating rate of 3 °C / min and held at that temperature for 6 h; then cooled to room temperature in water at 15 °C to obtain the precursor Li₂Fe. 0.8 Mn 0.2 SO.

[0150] (2) A working electrode was formed by mixing 0.9 g of the precursor with 0.1 g of super P. A sodium-ion battery was assembled using a Whatman glass fiber diaphragm and commercial sodium electrolyte NaClO4 (1.0 M in EC:DEC = 1:1 Vol%), with sodium metal as the counter electrode. The battery was charged at a constant current of 22.7 mA / g for 2.5 h to obtain Li. 1.75 Fe 0.8 Mn 0.2 SO; then constant current discharge was performed for 2.5 hours at a current of 22.7 mA / g to obtain Na. 0.25 Li 1.75 Fe 0.8 Mn 0.2 SO.

[0151] Experimental Example 1

[0152] The anti-perovskite materials prepared in Examples 2, 20, and 21 were characterized by X-ray diffraction, and the XRD patterns are shown below. Figures 3 to 5 As shown.

[0153] from Figures 3 to 5It can be seen that the materials prepared in Examples 2, 20 and 21 all have an anti-perovskite structure phase, indicating that anti-perovskite materials were prepared in Examples 2, 20 and 21.

[0154] Furthermore, from Figure 4 and Figure 5 The comparison shows that, compared to the Na prepared in Example 20, 0.75 Li 1.25 Fe 0.8 Mn 0.2 SO, Na prepared in Example 21 0.85 Li 1.15 Fe 0.8 Mn 0.2 The presence of numerous impurity phases in the XRD pattern of SO indicates that when anti-perovskite materials are prepared using solid-state synthesis, if the number of Li atoms in the chemical formula of the anti-perovskite material is less than 1.2, the resulting anti-perovskite material will have a large number of impurity phases.

[0155] Experiment Example 2

[0156] The materials prepared in Examples 1-21 and Comparative Examples 1-2 were used as positive electrode materials to assemble liquid half-cells. The first-cycle discharge specific capacity and cycle performance of the prepared sodium-ion batteries were tested, and the test results are shown in Table 1.

[0157] The preparation steps of the sodium-ion battery are as follows: The materials obtained in Examples 1-13 and Comparative Examples 1-8 are mixed with a conductive agent (Super P) and a binder (polyvinylidene fluoride) in a mass ratio of 7:2:1, and then dispersed in the solvent N-methylpyrrolidone (NMP). The mixture is then uniformly spin-coated onto the current collector aluminum foil. After the solvent is evaporated, the mixture is combined with a glass fiber separator, a metallic sodium anode, and a sodium electrolyte (ethylene carbonate and dimethyl carbonate in a volume ratio of 1:1). NaClO4 (with a concentration of 1M in the electrolyte) is also added to assemble a liquid half-cell.

[0158] Table 1

[0159]

[0160]

[0161] As can be seen from Table 1, the sodium-ion batteries prepared using the materials of Examples 1-21 have significantly better first-cycle discharge specific capacity and cycle performance than the sodium-ion batteries prepared using the materials of Comparative Examples 1-2.

[0162] As can be seen from Examples 1-17, electrochemical ion exchange can be used to prepare cathode materials that are beneficial to improving the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries.

[0163] As can be seen from Examples 1-9, when the atomic ratio specified in this application is met, the atomic ratios of Na, Li, and transition metal elements (i.e., Na₂) are satisfied. x Li y TM z Ch m O n By controlling the atomic ratio of TM in the material, sodium-ion batteries made from the prepared material can achieve higher first-cycle discharge specific capacity and better cycle performance.

[0164] As can be seen from Examples 1 and 10-14, when the number of oxygen atoms in the prepared material is greater than or equal to the number of chalcogenide (Ch) atoms, the first-cycle discharge specific capacity and cycle performance of the sodium-ion battery can be improved simultaneously. Furthermore, based on the premise that "the number of oxygen atoms in the prepared material is greater than or equal to the number of chalcogenide (Ch) atoms", further adjusting the ratio of the number of oxygen atoms to the number of chalcogenide (Ch) atoms can further affect the first-cycle discharge specific capacity and cycle performance of the sodium-ion battery.

[0165] As can be seen from Examples 15 and 1, the chemical formula Na... x Li y TM z Ch m O n The TM material can be Fe, Mn, Co or Ni, all of which can achieve high first-cycle discharge specific capacity and good cycle performance in sodium-ion batteries.

[0166] As can be seen from Examples 16 and 1, the chemical formula Na... x Li y TM z Ch m O n Choosing either S or Se for Ch can achieve sodium-ion batteries with high first-cycle discharge specific capacity and good cycle performance; and compared to choosing Se for Ch, choosing S for Ch is beneficial to further improve the first-cycle discharge specific capacity of sodium-ion batteries.

[0167] As can be seen from Examples 17 and 1, the cooling rate after ball milling and heat preservation can affect the first discharge specific capacity and cycle performance of sodium-ion batteries.

[0168] As can be seen from Examples 18-21, solid-state synthesis can be used to prepare cathode materials that are beneficial to improving the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries. However, when anti-perovskite materials are prepared by solid-state synthesis, if the number of Li atoms in the chemical formula of the anti-perovskite material is less than 1.2, the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries will be reduced.

[0169] In summary, this application uses Na, Li, transition metals, chalcogenides, and oxygen, and controls the ratio of each element to prepare an anti-perovskite material. Using this anti-perovskite material as a cathode material can improve the first-cycle discharge specific capacity and cycle performance of sodium-ion batteries prepared using this cathode material.

[0170] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. An anti-perovskite material, characterized in that, The anti-perovskite material has an anti-perovskite structural phase, and the general chemical expression formula of the anti-perovskite material is Na. x Li y TM z Ch m O n ; Wherein, 1.5≥x≥0.4, 1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2, TM is selected from transition metal elements, and Ch is selected from chalcogens.

2. The anti-perovskite material according to claim 1, characterized in that, The n is greater than or equal to the m.

3. The anti-perovskite material according to claim 2, characterized in that, The ratio of m to n is 1:(1.00-1.15).

4. The anti-perovskite material according to claim 3, characterized in that, The ratio of m to n is 1:(1.05-1.11).

5. The anti-perovskite material according to claim 1, characterized in that, The TM is selected from at least one of Fe, Co, Mn, Ni, V, Ti, W, Cr and Cu.

6. The anti-perovskite material according to claim 5, characterized in that, The TM includes Fe and Mn.

7. The anti-perovskite material according to claim 1, characterized in that, The Ch is selected from S.

8. The anti-perovskite material according to any one of claims 1-7, characterized in that, The anti-perovskite material is Na. 1.5 Li 0.5 Fe 0.8 Mn 0.2 SO, NaLi 0.75 Fe 0.8 Mn 0.2 S 0.95 O 1.05 NaLi 0.75 Fe 0.8 Mn 0.2 S 0.975 O 1.025 or NaLi 0.75 Fe 0.8 Mn 0.2 SO.

9. The anti-perovskite material according to claim 8, characterized in that, The anti-perovskite material is NaLi 0.75 Fe 0.8 Mn 0.2 S 0.95 O 1.05 .

10. A method for preparing an anti-perovskite material as described in any one of claims 1-9, characterized in that, include: The precursor is converted into the anti-perovskite material by electrochemical ion exchange. The general chemical formula of the anti-perovskite material is Na. x Li y TM z Ch m O n The precursor has the general chemical formula Li a TM z Ch m O n The precursor has an anti-perovskite structure phase; in the general chemical formula of the anti-perovskite material and the general chemical formula of the precursor, 1.5≥x≥0.4, 1.6≥y≥0.5, 0.8≤z≤1.2, 0.8≤m≤1.2, 0.8≤n≤1.2, a>y, TM is selected from transition metal elements, and Ch is selected from chalcogens.

11. The preparation method according to claim 10, characterized in that, The method for preparing the precursor includes: sequentially ball milling and heating the mixed raw materials; The raw materials include: Li2O, the element corresponding to TM, and the element corresponding to Ch; the heating treatment temperature is 600-800℃.

12. The preparation method according to claim 11, characterized in that, The method for preparing the precursor further includes: after the heat treatment, cooling the system after the heat treatment; the cooling step includes: cooling the system after the heat treatment to 10-30℃ at a temperature of 50-100℃ / min.

13. A method for preparing an anti-perovskite material as described in any one of claims 1-9, characterized in that, The mixed raw materials were then subjected to ball milling and heat treatment in sequence. The raw materials include a sodium source, a lithium source, and a substance containing the TM. The sodium source includes at least one of Na2O and Na2Ch; the lithium source includes at least one of Li2O and Li2Ch; the substance containing TM includes at least one of the following: a substance composed of TM and O element and a substance composed of TM and Ch.

14. A preparation method according to claim 13, characterized in that, The ball mill rotates at a speed of 400-800 rpm; And / or, the temperature of the heat treatment is 400-700℃; And / or, the method for preparing the anti-perovskite material further includes: after the heat treatment, cooling the system after the heat treatment; the cooling step includes: cooling the system after the heat treatment to 10-30℃ at a temperature of 50-100℃ / min. And / or, in the general chemical expression formula of the anti-perovskite material, 1.6 ≥ y ≥ 1.

2.

15. A positive electrode material, characterized in that, The cathode material includes the anti-perovskite material as described in any one of claims 1-9.

16. A sodium-ion battery, characterized in that, The sodium-ion battery includes the positive electrode material as described in claim 15.

Images