Preparation method of layered sodium ion battery positive electrode material

Abstract

The application relates to a preparation method of a layered sodium ion battery positive electrode material, and belongs to the technical field of sodium ion batteries, to solve the problems that the residual alkali content of the positive electrode material prepared by the existing method is high due to high sodium content, and the capacity and other performances of the sodium ion battery are affected. The specific proportion of each element in the positive electrode material is adopted, the sodium content is improved, the proportion of active sodium of the material is improved, the obtained sodium ion battery has high capacity, the residual alkali content of the material can be kept within a reasonable range, and the consistency and stability of the battery are good under the high sodium content of the application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sodium ion batteries, in particular to a preparation method of a layered sodium ion battery positive electrode material. BACKGROUND

[0002] The energy density of sodium ion batteries is relatively low, although the layered oxide positive electrode material has a high theoretical capacity, but its available capacity is limited, and it is not easy to introduce other elements on the basis of product standardization, the proportion adjustment involves subsequent new product development process, and the electrolyte is difficult to adapt at a higher voltage. Therefore, it is particularly important to find a means to improve the capacity within the existing voltage range on the existing process.

[0003] The existing capacity-improving means mainly include element doping improvement structure, proportion adjustment and new material at a higher voltage of existing elements. However, the current electrolyte system is difficult to adapt at a higher voltage, and element doping improvement needs to introduce other elements, which is difficult to operate on the existing production line; after proportion adjustment, the performance of the material needs to be re-evaluated, and the subsequent system development needs to be completely overturned, which is time-consuming and labor-intensive; the development of new materials is difficult, and the production process is also difficult to consider.

[0004] Too high sodium content will result in high alkalinity of the material, high residual alkali content will cause the cell slurry to gel easily, and gas is easily produced during the charging and discharging process of the cell, and even high-nickel materials need to be washed, coated with multiple layers and doped with multiple elements to reduce the residual alkali content. However, the theoretical capacity of the material and the molar ratio of Na have a direct linear relationship, and the amount of sodium has a certain influence on the capacity of the material, and the consistency and stability of the material can be improved at a higher sodium content. The positive electrode material prepared by the method of the prior art cannot simultaneously meet the requirements of rich sodium and low residual alkali content. SUMMARY

[0005] In view of the above analysis, the embodiments of the present application aim to provide a preparation method of a layered sodium ion battery positive electrode material to solve the problem that the residual alkali content of the positive electrode material prepared by the existing method is high when the sodium content is high, thereby affecting the capacity and other performances of the sodium ion battery.

[0006] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0007] A preparation method of a layered sodium ion battery positive electrode material, comprising the following steps:

[0008] (1) According to the molar ratio: 0.9 Na≤0.98, 0.05≤Cu≤0.20, 0.32≤Mn≤0.40, 0.01≤Li≤0.07, 0.08≤Ni≤0.22, 0.33≤Fe≤0.40, 0≤M≤0.05, respectively, each metal source is weighed for standby;

[0009] (2) mixing the standby metal sources, drying, high-temperature calcination, crushing, and sieving to obtain the positive electrode material;

[0010] Wherein, the M is one or several of Mg, Ca, B, Al, Li, K, Ag, Zr, Ti, W, Mo, Cr, Sr, Y, Cd, Sn, Sb, Ce.

[0011] Further, in step (2), the high-temperature calcination temperature is (800+400t2)~1050℃, and the calcination time is 8-24h, wherein t2 is the molar ratio of Ni element.

[0012] Further, in step (2), the heating rate during high-temperature calcination is 1-5℃ / min.

[0013] Further, in step (2), the high-temperature calcination atmosphere is air or oxygen.

[0014] Further, the general formula of the positive electrode material is

[0015] Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 M a2 O 2+nδ ;

[0016] Wherein, 0.9

[0017] Further, the general formula of the positive electrode material is Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 (M a21 M a22 )O 2+nδ , M a21 and M a22The elements represented by M are different, wherein 0.9

[0018] Further, the general formula of the positive electrode material is Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 (M a31 M a32 M a33 )O 2+nδ , M a31 , M a32 and M a33 The elements represented by M are different, wherein 0.9

[0019] Further, the general formula of the positive electrode material is

[0020] Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 (M a41 M a42 M a43 M a44 M a45 )O 2+nδ , M a41 , M a42 , M a43 , M a44 and M a45The elements represented by M are all different, wherein 0.9 < x2 < 0.98, 0.05 < y2 < 0.20, 0.32 < z2 < 0.40, 0.01 < s2 < 0.07, 0.08 < t2 < 0.22, 0.33 < u2 < 0.40, 0 < a41 + a42 + a43 + a44 + a45 < 0.05, x2 + 2y2 + 3z2 + 3u2 + 2(a41 + a42 + a43 + a44 + a45) + s2 + 2t2 < 4 < x2 + 2y2 + 4z2 + 3u2 + 4(a41 + a42 + a43 + a44 + a45) + s2 + 3t2, y2 + z2 + (a41 + a42 + a43 + a44 + a45) + s2 + t2 + u2 = 1.

[0021] Further, the positive electrode material is of O3 type.

[0022] Further, the total amount of residual alkali of the positive electrode material is 1.5-2.2%, the sodium carbonate content is 1-2.19%, and the sodium hydroxide content is 0.01-0.5%.

[0023] Compared with the prior art, the present application can achieve at least one of the following beneficial effects:

[0024] (1) The positive electrode material prepared by the present application has a specific ratio of elements, which improves the sodium content, increases the proportion of active sodium of the positive electrode material, and thus the obtained sodium ion battery has a high capacity, and the residual alkali content of the positive electrode material of the present application can be kept within a reasonable range, and the consistency and stability of the battery are good under the high sodium content of the present application.

[0025] (2) In the preparation process of the positive electrode material of the present application, a relationship between the calcination temperature and the content of Ni element is established, and under the calcination temperature of the present application, the total amount of residual alkali of the positive electrode material can be 1.5-2.2%, the sodium carbonate content can be 1-2.19%, and the sodium hydroxide content can be 0.01-0.5%, the battery prepared by using the positive electrode material of the present application has a higher capacity, and the electrochemical performance consistency of the battery is good.

[0026] (3) The positive electrode material prepared by the method of the present application does not need to increase the capacity by increasing the voltage, and the electrolyte has a wide adaptation range.

[0027] (4) The preparation method of the positive electrode material of the present application is simple, low in cost, and can be mass-produced.

[0028] The technical solutions in the present application can be combined with each other to realize more preferred combination solutions. Other features and advantages of the present application will be described in the following description, and some advantages will become apparent from the description, or will be learned by practice of the present application. The objects and other advantages of the present application can be realized and obtained by the content particularly pointed out in the description and the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application.

[0030] Figure 1 SEM image of the positive electrode material prepared for the present application embodiment 1;

[0031] Figure 2 SEM image of the positive electrode material prepared for the present application embodiment 7. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, wherein the accompanying drawings form a part of the present application and are used to explain the principles of the present application together with the embodiments of the present application, but are not used to limit the scope of the present application.

[0033] In one specific embodiment of the present application, a preparation method of a layered sodium ion battery positive electrode material is disclosed, comprising the following steps:

[0034] (1) According to the molar ratio: 0.9

[0035] (2) The prepared metal sources are mixed, dried, high-temperature calcined, crushed, and sieved to obtain the positive electrode material;

[0036] Wherein, the M is one or more of Mg, Ca, B, Al, Li, K, Ag, Zr, Ti, W, Mo, Cr, Sr, Y, Cd, Sn, Sb, and Ce.

[0037] Compared with the prior art, the method of the present application uses specific ratios of elements, improves the sodium content, increases the proportion of active sodium of the positive electrode material, and thus the obtained sodium ion battery has a higher capacity, and the positive electrode material of the present application can keep the residual alkali content within a reasonable range, and the consistency and stability of the battery are good under the higher sodium content of the present application.

[0038] It should be noted that, the Na content is too high, the residual alkali content is too high, the capacity is too low, the Cu content is too high, the impurities are difficult to be dissolved, the air stability is poor, the Mn content is too high, the cycle is poor, the electrolyte is seriously decomposed, the structure is unstable, the Li content is too low, the rate is poor, the structure is unstable, the Ni content is too high, the working voltage is low, the cycle is poor, the Fe content is too high, the cycle is poor and the element is high pressure migration, the capacity is low, M is only an additive, the capacity is affected, and the capacity is low.

[0039] Specifically, in step (2), the high-temperature calcination temperature is (800+400t2)-1050℃, and the calcination time is 8-24h, wherein t2 is the molar ratio of Ni element.

[0040] In the preparation of the positive electrode material, the relationship between the calcination temperature and the content of Ni element is established, and the total residual alkali content of the positive electrode material is 1.5-2.2%, the sodium carbonate content is 1-2.19%, and the sodium hydroxide content is 0.01-0.5% under the calcination temperature of the application.

[0041] Specifically, in step (2), the heating rate during high-temperature calcination is 1-5℃ / min.

[0042] Specifically, in step (2), the high-temperature calcination atmosphere is air or oxygen.

[0043] In one specific embodiment of the application, the general formula of the positive electrode material prepared by the above method is Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 M a2 O 2+nδ ;

[0044] Wherein, 0.9

[0045] In another specific embodiment of the application, the general formula of the positive electrode material prepared by the above method is Na x2 Cu y2 Mn z2Li s2 Ni t2 Fe u2 (M a21 M a22 )O 2+nδ , M a21 and M a22 , wherein the elements represented by M are different, and wherein 0.9 < x2 < 0.98, 0.05 < y2 < 0.20, 0.32 < z2 < 0.40, 0.01 < s2 < 0.07, 0.08 < t2 < 0.22, 0.33 < u2 < 0.40, 0 < a21 + a22 < 0.05, x2 + 2y2 + 3z2 + 3u2 + 2(a21 + a22) + s2 + 2t2 < 4 < x2 + 2y2 + 4z2 + 3u2 + 4(a21 + a22) + s2 + 3t2, y2 + z2 + (a21 + a22) + s2 + t2 + u2 = 1, 0 < n < 0.05, and -1 < δ < 3.

[0046] Another embodiment of the present application discloses a positive electrode material prepared by the above method, and the general formula of the positive electrode material is Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 (M a31 M a32 M a33 )O 2+nδ , M a31 , M a32 and M a33 , wherein the elements represented by M are different, and wherein 0.9 < x2 < 0.98, 0.05 < y2 < 0.20, 0.32 < z2 < 0.40, 0.01 < s2 < 0.07, 0.08 < t2 < 0.22, 0.33 < u2 < 0.40, 0 < a31 + a32 + a33 < 0.05, x2 + 2y2 + 3z2 + 3u2 + 2(a31 + a32 + a33) + s2 + 2t2 < 4 < x2 + 2y2 + 4z2 + 3u2 + 4(a31 + a32 + a33) + s2 + 3t2, y2 + z2 + (a31 + a32 + a33) + s2 + t2 + u2 = 1, 0 < n < 0.05, and -1 < δ < 3.

[0047] Another embodiment of the present application discloses the positive electrode material, and the general formula of the positive electrode material is Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 (M a41 M a42 Ma43 M a44 M a45 )O 2+nδ M a41 M a42 M a43 M a44 and M a45 In the given equation, M represents different elements, where 0.9 < x² ≤ 0.98, 0.05 ≤ y² ≤ 0.20, 0.32 ≤ z² ≤ 0.40, 0.01 ≤ s² ≤ 0.07, 0.08 ≤ t² ≤ 0.22, 0.33 ≤ u² ≤ 0.40, 0 ≤ a₄₁ + a₄₂ + a₄₃ + a₄₄ + a₄₅ ≤ 0.05, and x² + 2y² + 3z² + 3u² +2(a41+a42+a43+a44+a45)+s2+2t2<4<x2+2y2+4z2+3u2+4(a41+a42+a43+a44+ a45)+s2+3t2, y2+z2+(a41+a42+a43+a44+a45)+s2+t2+u2=1, 0<n≤0.05, -1≤δ≤3.

[0048] Specifically, the cathode material is of the O3 type.

[0049] Specifically, the total residual alkali content of the cathode material is 1.5-2.2%, for example, 1.5%, 1.6%, 1.7%, 1.78%, 1.8%, 1.9%, 2.0%, 2.1%, and 2.2%.

[0050] In a preferred embodiment, the total residual alkali of the cathode material is 1.78-2.2%.

[0051] Specifically, the sodium carbonate content is 1-2.19%, for example, 1%, 1.2%, 1.4%, 1.6%, 1.76%, 1.8%, 2.01%, 2.1%, and 2.19%, and the sodium hydroxide content is 0.01-0.5%, for example, 0.01%, 0.019%, 0.05%, 0.10%, 0.15%, 0.12%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, and 0.5%.

[0052] In the preferred embodiment, the sodium carbonate content is 1.76-2.01%, and the sodium hydroxide content is 0.019-0.12%.

[0053] Another embodiment of the present invention discloses a sodium-ion battery, including the aforementioned layered sodium-ion battery cathode material.

[0054] Compared with the prior art, the sodium-ion battery of the present invention has a higher active sodium ratio, which improves the capacity of the sodium-ion battery, and has lower requirements for electrolyte, resulting in better battery stability.

[0055] It should be noted that the battery consistency in the present application refers to the capacity difference of the three batteries selected as the maximum value, the minimum value and the median value in the same batch of batteries during the test process, and the details are shown in Table 1. If the capacities of the three batteries at the same rate and different rates are similar, the consistency is good.

[0056] The positive electrode material described in the present application is explained and described below in combination with specific examples.

[0057] Example 1

[0058] The preparation method of the layered sodium-ion battery positive electrode material of the present embodiment comprises the following steps:

[0059] (1) According to the molar ratio: Na0.98, Cu0.12, Mn0.37, Ni0.1, Fe0.36, Li0.04, Al0.01, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, Al2O3 and MnO2 are weighed as raw materials for standby;

[0060] (2) The standby raw materials are mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h, with a heating rate of 2℃ / min, crushed, and sieved to obtain the positive electrode material, denoted as B2.

[0061] The positive electrode material prepared in the present embodiment is O3 type, and the general formula is

[0062] Na 0.98 Cu 0.12 Mn 0.37 Ni 0.1 Fe 0.36 Li 0.04 Al 0.01 O2.

[0063] Example 2

[0064] The preparation method of the layered sodium-ion battery positive electrode material of the present embodiment comprises the following steps:

[0065] (1) According to the molar ratio: Na0.98, Cu0.12, Mn0.37, Ni0.1, Fe0.36, Li0.04, Al0.01, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, Al2O3 and MnO2 are weighed as raw materials for standby;

[0066] (2) The standby raw materials are mixed uniformly, dried, and calcined at 840℃ under compressed air atmosphere for 16h, with a heating rate of 2℃ / min, crushed, and sieved to obtain the positive electrode material, denoted as B2-1.

[0067] The positive electrode material prepared in the embodiment is of O3 type, and the general formula is

[0068] Na 0.98 Cu 0.12 Mn 0.37 Ni 0.1 Fe 0.36 Li 0.04 Al 0.01 O2.

[0069] Example 2-1

[0070] The preparation method of the layered sodium-ion battery positive electrode material in the embodiment comprises the following steps:

[0071] (1) Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, MnO2 and ZrO2 are weighed as raw materials according to the molar ratio of Na0.98, Cu0.12, Mn0.35, Ni0.1, Fe0.37, Li0.04 and Zr0.02 respectively for standby;

[0072] (2) The standby raw materials are mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h at a heating rate of 2℃ / min, crushed, and sieved to obtain the positive electrode material, which is recorded as B2-4.

[0073] The positive electrode material prepared in the embodiment is of O3 type, and the general formula is

[0074] Na 0.98 Cu 0.12 Mn 0.32 Ni 0.1 Fe 0.37 Li 0.04 Ti 0.05 O2.

[0075] Example 2-2

[0076] The preparation method of the layered sodium-ion battery positive electrode material in the embodiment comprises the following steps:

[0077] (1) Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, MnO2 and ZrO2 are weighed as raw materials according to the molar ratio of Na0.98, Cu0.12, Mn0.35, Ni0.1, Fe0.37, Li0.04 and Zr0.02 respectively for standby;

[0078] (2) The standby raw materials are mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h at a heating rate of 2℃ / min, crushed, and sieved to obtain the positive electrode material, which is recorded as B2-4.

[0079] The positive electrode material prepared in the embodiment is of O3 type, and the general formula is

[0080] Na 0.98 Cu 0.12 Mn 0.35 Ni 0.1 Fe 0.37 Li 0.04 Zr 0.02 O2.

[0081] Example 2-3

[0082] The preparation method of the layered sodium-ion battery positive electrode material in the embodiment comprises the following steps:

[0083] (1) Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, MnO2 and SnO2 were weighed as raw materials according to the molar ratio of Na0.98, Cu0.12, Mn0.36, Ni0.1, Fe0.37, Li0.04 and Sn0.01 respectively for standby;

[0084] (2) The standby raw materials were mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h at a heating rate of 2℃ / min, crushed, and sieved to obtain the positive electrode material, which is recorded as B2-5.

[0085] The positive electrode material prepared in the embodiment is of O3 type, and the general formula is

[0086] Na 0.98 Cu 0.12 Mn 0.36 Ni 0.1 Fe 0.37 Li 0.04 Sn 0.01 O2.

[0087] Example 2-4

[0088] The preparation method of the layered sodium-ion battery positive electrode material in the embodiment comprises the following steps:

[0089] (1) Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, MnO2 and CeO2 were weighed as raw materials according to the molar ratio of Na0.98, Cu0.12, Mn0.36, Ni0.1, Fe0.37, Li0.04 and Ce0.01 respectively for standby;

[0090] (2) The standby raw materials were mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h at a heating rate of 2℃ / min, crushed, and sieved to obtain the positive electrode material, which is recorded as B2-6.

[0091] The positive electrode material prepared in this embodiment is O3 type, and the general formula is

[0092] Na 0.98 Cu 0.12 Mn 0.36 Ni 0.1 Fe 0.37 Li 0.04 Ce 0.01 O2.

[0093] Example 2-5

[0094] The preparation method of the layered sodium-ion battery positive electrode material in this embodiment comprises the following steps:

[0095] (1) Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, MnO2 and CaO were weighed as raw materials according to the molar ratio of Na0.98, Cu0.10, Mn0.37, Ni0.1, Fe0.37, Li0.04 and Ca0.02 respectively for standby;

[0096] (2) The standby raw materials were mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h, the heating rate was 2℃ / min, and then crushed, screened, to obtain the positive electrode material, recorded as B2-8.

[0097] The positive electrode material prepared in this embodiment is O3 type, and the general formula is

[0098] Na 0.98 Cu 0.09 Mn 0.37 Ni 0.1 Fe 0.37 Li 0.04 Mg 0.03 O2.

[0099] Example 2-6

[0100] The preparation method of the layered sodium-ion battery positive electrode material in this embodiment comprises the following steps:

[0101] (1) Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, MnO2 and CaO were weighed as raw materials according to the molar ratio of Na0.98, Cu0.10, Mn0.37, Ni0.1, Fe0.37, Li0.04 and Ca0.02 respectively for standby;

[0102] (2) The standby raw materials were mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h, the heating rate was 2℃ / min, and then crushed, screened, to obtain the positive electrode material, recorded as B2-8.

[0103] The positive electrode material prepared in the embodiment is of O3 type, and the general formula is

[0104] Na 0.98 Cu 0.10 Mn 0.37 Ni 0.1 Fe 0.37 Li 0.04 Ca 0.02 O2.

[0105] Example 2-7

[0106] The preparation method of the layered sodium-ion battery positive electrode material in the embodiment comprises the following steps:

[0107] (1) Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, B2O3, MnO2 and K2CO3 are respectively weighed as raw materials for standby according to the molar ratio of Na0.98, Cu0.10, Mn0.37, Ni0.08, Fe0.37, Li0.04, B0.02 and K0.02,

[0108] (2) The standby raw materials are uniformly mixed, dried, and calcined at 910℃ under compressed air atmosphere for 16h, the heating rate is 2℃ / min, and then crushed, screened, and the positive electrode material is obtained, which is recorded as B2-9.

[0109] The positive electrode material prepared in the embodiment is of O3 type, and the general formula is

[0110] Na 0.98 Cu 0.10 Mn 0.37 Ni 0.08 Fe 0.37 Li 0.04 B 0.02 K 0.02 O2.

[0111] Example 2-8

[0112] The preparation method of the layered sodium-ion battery positive electrode material in the embodiment comprises the following steps:

[0113] (1) Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, Ag2O, WO3, MnO2 and SrCO3 are respectively weighed as raw materials for standby according to the molar ratio of Na0.98, Cu0.10, Mn0.36, Ni0.09, Fe0.37, Li0.04, Ag0.02, W0.01 and Sr0.01;

[0114] (2) The standby raw materials are mixed uniformly, dried, and high-temperature calcined under compressed air atmosphere at 910℃ for 16h, with a heating rate of 2℃ / min, crushed, sieved, to obtain the positive electrode material, denoted as B2-10.

[0115] The positive electrode material prepared in this example is of O3 type, with a general formula of

[0116] Na 0.98 Cu 0.10 Mn 0.36 Ni 0.09 Fe 0.37 Li 0.04 Ag 0.02 W 0.01 Sr 0.01 O2.

[0117] Example 2-9

[0118] The preparation method of the layered sodium-ion battery positive electrode material in this example comprises the following steps:

[0119] (1) According to the molar ratio: Na0.98, Cu0.11, Mn0.33, Ni0.10, Fe0.37, Li0.04, Y0.01, Mo0.01, Cr0.01, Cd0.01, Sb0.01, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, Y2O3, MoO3, CdO, Cr2O3, MnO2 and Sb2O3 are weighed as standby raw materials;

[0120] (2) The standby raw materials are mixed uniformly, dried, and high-temperature calcined under compressed air atmosphere at 910℃ for 16h, with a heating rate of 2℃ / min, crushed, sieved, to obtain the positive electrode material, denoted as B2-11.

[0121] The positive electrode material prepared in this example is of O3 type, with a general formula of

[0122] Na 0.98 Cu 0.11 Mn 0.33 Ni 0.10 Fe 0.37 Li 0.04 Y 0.01 Mo 0.01 Cr 0.01 Cd 0.01 Sb 0.01 O2.

[0123] Example 3

[0124] The preparation method of the layered sodium-ion battery positive electrode material in this example comprises the following steps:

[0125] (1) According to the molar ratio: Na0.98, Cu0.12, Mn0.37, Ni0.1, Fe0.36, Li0.04, Al0.01, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, Al2O3 and MnO2 are weighed as raw materials for standby respectively;

[0126] (2) The standby raw materials are mixed uniformly, dried, and calcined at 1050℃ under compressed air atmosphere for 16h, the heating rate is 2℃ / min, crushed, sieved, to obtain the positive electrode material, recorded as B2-2.

[0127] The positive electrode material prepared in this example is O3 type, the general formula is

[0128] Na 0.98 Cu 0.12 Mn 0.37 Ni 0.1 Fe 0.36 Li 0.04 Al 0.01 O2.

[0129] Example 4

[0130] The preparation method of the layered sodium ion battery positive electrode material in this example comprises the following steps:

[0131] (1) According to the molar ratio: Na0.94, Cu0.05, Mn0.4, Ni0.1, Fe0.33, Li0.07, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2 and MnO2 are weighed as raw materials for standby respectively;

[0132] (2) The standby raw materials are mixed uniformly, dried, and calcined at 910℃ under compressed oxygen atmosphere for 16h, the heating rate is 2℃ / min, crushed, sieved, to obtain the positive electrode material, recorded as B6.

[0133] The positive electrode material prepared in this example is O3 type, the general formula is

[0134] Na 0.94 Cu 0.05 Mn 0.4 Ni 0.1 Fe 0.33 Li 0.07 O2.

[0135] Example 5

[0136] The preparation method of the layered sodium ion battery positive electrode material in this example comprises the following steps:

[0137] (1) According to the molar ratio: Na0.95, Cu0.18, Mn0.33, Ni0.08, Fe0.40, Li0.01, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2 and MnO2 are weighed as raw materials respectively for standby;

[0138] (2) The standby raw materials are mixed uniformly, dried, and calcined at 980℃ under compressed air atmosphere for 16h, the heating rate is 2℃ / min, crushed, sieved, to obtain the positive electrode material, recorded as B7.

[0139] The positive electrode material prepared in this example is O3 type, the general formula is

[0140] Na 0.95 Cu 0.18 Mn 0.33 Ni 0.08 Fe 0.40 Li 0.01 O2.

[0141] Example 6

[0142] The preparation method of the layered sodium ion battery positive electrode material in this example comprises the following steps:

[0143] (1) According to the molar ratio: Na0.95, Cu0.05, Mn0.34, Ni0.22, Fe0.33, Li0.01, Al0.05, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, Al2O3 and MnO2 are weighed as raw materials respectively;

[0144] (2) The standby raw materials are mixed uniformly, dried, and calcined at 960℃ under compressed air atmosphere for 16h, the heating rate is 2℃ / min, crushed, sieved, to obtain the positive electrode material, recorded as B8.

[0145] The positive electrode material prepared in this example is O3 type, the general formula is Na 0.95 Cu 0.05 Mn 0.34 Ni 0.22 Fe 0.33 Li 0.01 Al 0.05 O2. Example 7

[0146] The preparation method of the layered sodium ion battery positive electrode material in this example comprises the following steps:

[0147] (1) According to the molar ratio: Na0.92, Cu0.2, Mn0.38, Ni0.08, Fe0.33, Li0.01, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2and MnO2are weighed as raw materials respectively;

[0148] (2) The standby raw materials are mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h, the heating rate is 2℃ / min, crushed, sieved, to obtain the positive electrode material, recorded as B9.

[0149] The positive electrode material prepared in this example is O3 type, the general formula is

[0150] Na 0.92 Cu 0.2 Mn 0.38 Ni 0.08 Fe 0.33 Li 0.01 O2.

[0151] Comparative Example 1

[0152] The preparation method of the positive electrode material in this comparative example comprises the following steps:

[0153] (1) According to the molar ratio: Na0.9, Cu0.12, Mn0.37, Ni0.1, Fe0.36, Li0.04, Al0.01, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, Al2O3and MnO2are weighed as raw materials respectively for standby;

[0154] (2) The standby raw materials are mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h, the heating rate is 2℃ / min, crushed, sieved, to obtain the positive electrode material, recorded as A2.

[0155] The general formula of the positive electrode material prepared in this comparative example is

[0156] Na 0.9 Cu 0.12 Mn 0.37 Ni 0.1 Fe 0.36 Li 0.04 Al 0.01 O2.

[0157] Comparative Example 2

[0158] The preparation method of the positive electrode material in this comparative example comprises the following steps:

[0159] (1) According to the molar ratio: Na0.99, Cu0.12, Mn0.37, Ni0.1, Fe0.36, Li0.04, Al0.01, Na2CO3, CuO, Fe2O3, Li2CO3, Ni(OH)2, Al2O3 and MnO2 are weighed as raw materials for standby;

[0160] (2) The standby raw materials are mixed uniformly, dried, and calcined at 910℃ under compressed air atmosphere for 16h, the heating rate is 2℃ / min, crushed, sieved, to obtain the positive electrode material, recorded as A4.

[0161] The general formula of the positive electrode material prepared in the present comparative example is

[0162] Na 0.99 Cu 0.12 Mn 0.37 Ni 0.1 Fe 0.36 Li 0.04 Al 0.01 O2.

[0163] Comparative Example 3

[0164] The layered sodium-ion battery positive electrode material prepared in the present comparative example is O3 type, the general formula and preparation method are the same as those of Example 1, the difference is that the high-temperature calcination temperature is 830℃, to obtain the positive electrode material, recorded as C1.

[0165] Comparative Example 4

[0166] The layered sodium-ion battery positive electrode material prepared in the present comparative example is O3 type, the general formula and preparation method are the same as those of Example 1, the difference is that the high-temperature calcination temperature is 1060℃, to obtain the positive electrode material, recorded as C2.

[0167] Test Example 1

[0168] The battery is assembled, the positive electrode materials of Examples 1-7 and Comparative Examples 1-4 are used as active materials, mixed according to the mass ratio of active material SP: PVDF is 90:5:5, NMP is added to form a viscous glue, coated on aluminum foil, baked in a vacuum drying oven at 120℃ for 12h, to obtain a positive electrode sheet. With metal sodium sheet as the counter electrode, glass fiber (Waterman) as the separator, 1mol / L NaPF6EC / DMC=1:1(Alfa) as the electrolyte, 2032 button cell is assembled in Ar protection glove box.

[0169] (1) Test the battery in the voltage range of 2.5-4.0V, 0.1C activate for three weeks, 1C cycle for three weeks, record the 0.1C first week discharge specific capacity, 0.5C first discharge specific capacity and 1C first discharge specific capacity of the battery, the results are shown in Table 1.

[0170] Table 1

[0171]

[0172] As can be seen from Table 1, the 0.1C, 0.5C and 1C capacities of A2, A4, C1 and C2 are obviously different, and the capacities are also low; while the 0.1C, 0.5C and 1C capacities of B2-B2-11 and B6-B9 are basically at the same level and the consistency of the three batteries is good.

[0173] Compared with A2, A4 and B2, the 0.1C capacity is increased by more than 10 mAh / g, A2 is sodium-poor, A4 is sodium-excessive, B2 is sodium-rich, the rate performance of B2 is excellent and the capacity is stable, which shows that only the Na content of the application can make the capacity of the battery stable.

[0174] From the above analysis, it can be seen that only the Na content range of the application can make the prepared positive electrode material have excellent performance.

[0175] (2) Test the total amount of residual alkali of Examples 1-7 and Comparative Examples 1-4, the results are shown in Table 2, wherein the total amount of residual alkali (i.e. mass ratio) = mass ratio of sodium carbonate + mass ratio of sodium hydroxide.

[0176] Residual alkali amount test: obtained by Metrohm 888 / 905 instrument.

[0177] Table 2

[0178] Materials Mass ratio (sodium carbonate + sodium hydroxide) / % Mass ratio (sodium carbonate) / % Mass ratio (sodium hydroxide) / % B2 1.815 1.790 0.025 B2-1 2.121 2.010 0.111 B2-2 1.952 1.907 0.045 B2-3 1.814 1.792 0.022 B2-4 1.816 1.793 0.023 B2-5 1.815 1.791 0.024 B2-6 1.817 1.790 0.027 B2-7 1.812 1.791 0.021 B2-8 1.814 1.795 0.019 B2-9 1.816 1.792 0.024 B2-10 1.815 1.794 0.021 B2-11 1.818 1.796 0.022 B6 1.834 1.810 0.024 B7 1.802 1.780 0.022 B8 1.823 1.800 0.023 B9 1.781 1.760 0.021 A2 1.781 1.760 0.021 A4 2.721 2.630 0.091 C1 2.442 2.231 0.211 C2 2.231 2.198 0.033

[0179] As can be seen from Tables 1 and 2, compared with A2, A4 and B2, the total alkali amount of A2 is low but the capacity is difficult to develop, the total alkali amount of A4 is high, the contents of sodium carbonate and sodium hydroxide are also high, and the corresponding electrical performance is also poor, which shows that only the positive electrode material prepared by using the ratio of each element of the application has high capacity and low residual alkali amount.

[0180] In addition, compared with C1 and C2, only the sintering temperature is changed in B2, B2-1 and B2-2, when the temperature is lower than 840℃, the battery capacity is low and the sodium carbonate content is high, when the temperature is higher than 1050℃, although the battery capacity is increased, the consistency of the battery is poor, only when the sintering temperature is within the limit of the application, the battery capacity, residual alkali amount and battery consistency and other performances are all good.

[0181] (3) The SEM images of the measured materials B2 and B9 are shown in Figure 1 and 2 respectively. It can be seen from the images that the surfaces of the large particles of the measured materials are uniformly attached with small particles, and the residual alkali amount indicates that the material surface is rich in sodium.

[0182] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which shall be covered within the protection scope of the present application.

Claims

1. A method for preparing a layered sodium-ion battery cathode material, characterized in that, It comprises the following steps: (1) according to the molar ratio: 0.9 (2) mixing the prepared metal sources, drying, high-temperature calcination, crushing, and sieving to obtain the positive electrode material; Wherein, the M is one or more of Mg, Ca, B, Al, Li, K, Ag, Zr, Ti, W, Mo, Cr, Sr, Y, Cd, Sn, Sb, and Ce; In step (2), the high-temperature calcination temperature is (800+400t2)~1050℃, and the calcination time is 8-24h, wherein t2 is the molar ratio of Ni element; The total amount of residual alkali of the positive electrode material is 1.5-2.2%, the sodium carbonate content is 1-2.19%, and the sodium hydroxide content is 0.01-0.5%.

2. The production method according to claim 1, characterized by, In step (2), the heating rate during high-temperature calcination is 1-5℃ / min.

3. The production method according to claim 1 or 2, characterized by, In step (2), the high-temperature calcination atmosphere is air or oxygen.

4. The production method according to claim 1 or 2, characterized by, The positive electrode material has a general formula of Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 M a2 O 2+nδ ; Wherein, 0.9 5. The production method according to claim 1 or 2, characterized by, The positive electrode material has a general formula of Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 (M a21 M a22 )O 2+nδ , M a21 and M a22 represent different elements, wherein 0.9 0.05 0.32 0.01 0.08 0.33 0 x2+2y2+3z2+3u2+2(a21+a22)+s2+2t2 y2+z2+(a21+a22)+s2+t2+u2=1 0 -1 6. The production method according to claim 1 or 2, characterized by, The positive electrode material has a general formula of Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 (M a31 M a32 M a33 )O 2+nδ , M a31 , M a32 and M a33 represent different elements, wherein 0.9 0.05 0.32 0.01 0.08 0.33 0 x2+2y2+3z2+3u2+2(a31+a32+a33)+s2+2t2 4 x2+2y2+4z2+3u2+4(a31+a32+a33)+s2+3t2 y2+z2+(a31+a32+a33)+s2+t2+u2=1 0 -1 3.

7. The production method according to claim 1 or 2, characterized by, The positive electrode material has a general formula of Na x2 Cu y2 Mn z2 Li s2 Ni t2 Fe u2 (M a41 M a42 M a43 M a44 M a45 )O 2+nδ , M a41 , M a42 , M a43 , M a44 and M a45 , wherein the elements represented by M are different, 0.9 x2+2y2+3z2+3u2+2(a41+a42+a43+a44+a45)+s2+2t2 y2+z2+(a41+a42+a43+a44+a45)+s2+t2+u2=1.

8. The production method according to claim 1 or 2, characterized by, The positive electrode material is of O3 type.

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