A lead-based layered oxide material for sodium ion batteries and its preparation method and application

Abstract

The present invention relates to the technical field of sodium ion batteries, and discloses a lead-based layered oxide material for sodium ion batteries, a preparation method thereof, and an application thereof. The chemical formula of the lead-based layered oxide material is: Na a T 1‑b‑c‑d Mn b Fe c Pb d O e The lead-based layered oxide material is used as a positive electrode active material for a sodium-ion battery. The molar ratios of a, b, c, d, and e are the corresponding elements, respectively, and 0.70≤a≤1.25, 0.10≤b≤0.45, 0.10≤c≤0.45, 0.01≤d≤0.25, and 1.75≤e≤2.25. The lead-based layered oxide material of the present invention is simple to prepare, and the elements it contains are highly abundant in the Earth's crust, resulting in low raw material costs. Application of the lead-based layered oxide material can produce a sodium-ion battery with good cycle performance and excellent safety performance.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion batteries, and in particular to a lead-based layered oxide material for sodium ion batteries, and a preparation method and application thereof. Background Art

[0002] With the booming development of the new energy and energy storage industries, the price of lithium-ion batteries has continued to rise due to the limited availability of lithium resources. However, sodium is relatively abundant on Earth, so sodium-ion batteries have been widely researched.

[0003] In sodium-ion layered oxide cathode materials, transition metal elements typically form MO6 octahedral structures with six surrounding oxygen atoms, forming transition metal layers. Sodium ions are located between these transition metal layers, forming a layered structure with alternating MO6 polyhedral layers and NaO6 metal layers. These structures experience lattice distortion and phase transitions during the sodium ion charge and discharge process, hindering the transport and diffusion of sodium ions, leading to reduced cycling performance and potential safety hazards.

[0004] Chinese invention patent publication number CN 114906880 A discloses a method for preparing a sodium ion battery cathode material and a sodium ion battery. The method comprises the following steps: dissolving a sodium source, a nickel source, and a manganese source in deionized water to form a mixed solution; vigorously stirring the mixed solution, adding a complexing agent to the mixed solution during the stirring process, and maintaining the pH of the mixed solution at 8-9; evaporating and concentrating the mixed solution after adding the complexing agent to obtain a gel, and drying the gel; pre-calcining the dried gel at a first temperature and maintaining the temperature for a first period of time, and then calcining it at a second temperature and maintaining the temperature for a second period of time to obtain the final cathode material. However, the synergistic effect between the metal elements in the cathode material is not good, and the cycle performance of the sodium ion battery is not effectively improved. Summary of the Invention

[0005] In order to improve the electrochemical performance of the positive electrode material in sodium ion batteries, the present invention provides a lead-based layered oxide material for sodium ion batteries, a preparation method and application thereof. The lead-based layered oxide material obtained by doping with various metal elements has better coordination and synergistic effects between the elements. After application, a sodium ion battery with good cycle performance and excellent safety performance can be obtained.

[0006] The specific technical solutions of the present invention are:

[0007] In the first aspect, the present invention provides a lead-based layered oxide material for sodium ion batteries, wherein the chemical formula of the lead-based layered oxide material is: Na a T 1-b-c-d Mn b Fec Pb d O e ; The lead-based layered oxide material is used as a positive electrode active material for a sodium ion battery; a, b, c, d, and e are the molar ratios of the corresponding elements, and 0.70≤a≤1.25, 0.10≤b≤0.45, 0.10≤c≤0.45, 0.01≤d≤0.25, and 1.75≤e≤2.25.

[0008] The present invention uses lead doping to improve the electrochemical performance of layered sodium-ion cathode materials. Lead has a large atomic radius, and excessive doping can disrupt the structure of the cathode material. Furthermore, lead exhibits a synergistic effect with other metal elements. Furthermore, by further controlling the molar ratio of each element, the lead-based layered oxide material exhibits excellent electrochemical performance as a cathode material, with a capacity retention rate exceeding 89% after 170 cycles.

[0009] This lead-based layered oxide material is simple to prepare and contains elements that are abundant in the Earth's crust, resulting in low raw material costs. Applications of this lead-based layered oxide material can produce sodium-ion batteries with high gram capacity, good cycle performance, and excellent safety. These batteries can be used in the two-wheeled and three-wheeled vehicle industries, as well as in energy storage and communications.

[0010] Preferably, the T is one or a combination of two elements selected from Ni and Cu.

[0011] The combination of NiMnFe and CuMnFe elements, synergistically with lead elements, can achieve better cycle performance.

[0012] In a second aspect, the present invention further provides a method for preparing a lead-based layered oxide material for a sodium ion battery, comprising the following steps:

[0013] (1) mixing sodium carbonate, manganese oxide, ferric oxide, lead oxide, and T oxide according to the stoichiometric ratio in the general chemical formula, adding a solvent, and ball milling to obtain a precursor;

[0014] (2) The precursor is subjected to oxygen sintering, and then crushed and sieved to obtain a lead-based layered oxide material.

[0015] Preferably, the amount of sodium carbonate added is 1.01 to 1.10 times the theoretical stoichiometric value.

[0016] Taking into account the loss during the sintering process, the added amount of sodium carbonate is set to exceed the theoretical value.

[0017] Preferably, the oxygen sintering is performed at a sintering temperature of 600 to 950° C. and a sintering time of 10 to 36 hours.

[0018] Preferably, the solvent is anhydrous ethanol or water; more preferably anhydrous ethanol.

[0019] Preferably, the ball milling process parameters are: ball-to-material ratio of 10 to 20:1, and rotation speed of 150 to 300 r / min.

[0020] In a third aspect, the present invention also provides a positive electrode plate for a sodium ion battery, the positive electrode plate comprising a current collector and an active material layer bonded to the current collector; the active material layer contains the above-mentioned lead-based layered oxide material or the lead-based layered oxide material obtained by the above-mentioned preparation method.

[0021] In a fourth aspect, the present invention further provides a sodium ion battery, comprising the positive electrode sheet according to claim 8.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention adopts the method of doping lead elements and synergizing with other metal elements, and further limiting the molar ratio of each element to effectively improve the electrochemical performance of the layered sodium ion positive electrode material, and the capacity retention rate after 170 cycles can reach more than 89%;

[0024] (2) The lead-based layered oxide material is easy to prepare and the elements it contains are highly abundant in the earth's crust, so the raw material cost is low. The resulting sodium ion battery can be used in the two-wheeled vehicle industry, the three-wheeled vehicle industry, the energy storage industry, and the communications industry. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the embodiments.

[0026] Overall embodiment

[0027] A lead-based layered oxide material for sodium ion batteries, the general chemical formula of which is: Na a T 1-b-c-d Mn b Fe c Pb d O e , wherein T is a combination of one or two of Ni and Cu, a, b, c, d, and e are molar ratios of the corresponding elements, and 0.70≤a≤1.25, 0.10≤b≤0.45, 0.10≤c≤0.45, 0.01≤d≤0.25, and 1.75≤e≤2.25.

[0028] The method for preparing the lead-based layered oxide material for sodium ion batteries comprises the following steps:

[0029] (1) Sodium carbonate, manganese oxide, ferric oxide, lead oxide and T oxide are mixed according to the stoichiometric ratio in the general chemical formula, wherein the amount of sodium carbonate added is 1.01 to 1.10 times the theoretical value of the stoichiometric number; a solvent is added and ball milling is performed, wherein the ball-to-material ratio of the ball milling is 10 to 20:1 and the rotation speed is 150 to 300 r / min, and the solvent is anhydrous ethanol or water, to obtain a precursor;

[0030] (2) The precursor is subjected to oxygen sintering at a sintering temperature of 600-950°C and a sintering time of 10-36 hours. The sintered product is then crushed and sieved to obtain a lead-based layered oxide material.

[0031] A positive electrode plate for a sodium ion battery comprises a current collector and an active material layer bonded to the current collector, wherein the active material layer contains the above-mentioned lead-based layered oxide material.

[0032] A sodium ion battery comprising the above-mentioned positive electrode sheet.

[0033] Example 1

[0034] The general chemical formula of lead-based layered oxide materials is: Na 0.86 Cu 0.27 Fe 0.11 Mn 0.51 Pb 0.11 O2.

[0035] The preparation method of the lead-based layered oxide material comprises the following steps:

[0036] (1) Sodium carbonate, manganese oxide, ferric oxide, lead oxide, and copper oxide are mixed according to the stoichiometric ratio in the general chemical formula, wherein the amount of sodium carbonate added is 1.03 times the theoretical value of the stoichiometric number; anhydrous ethanol is added and ball milling is performed, with the ball-to-material ratio of the ball milling being 15:1 and the rotation speed being 200 r / min to obtain a precursor;

[0037] (2) The precursor is subjected to oxygen sintering at a sintering temperature of 910°C and a sintering time of 26 hours. After sintering, the resultant is naturally cooled and then crushed and sieved to obtain a lead-based layered oxide material.

[0038] Example 2

[0039] The general chemical formula of lead-based layered oxide materials is: Na 0.83 Cu 0.22 Fe 0.11 Mn 0.64 Pb 0.03 O2.

[0040] The preparation method of the lead-based layered oxide material comprises the following steps:

[0041] (1) Sodium carbonate, manganese oxide, ferric oxide, lead oxide, and copper oxide are mixed according to the stoichiometric ratio in the general chemical formula, wherein the amount of sodium carbonate added is 1.03 times the theoretical value of the stoichiometric number; anhydrous ethanol is added and ball milled at a ball-to-material ratio of 12:1 and a rotation speed of 250 r / min to obtain a precursor;

[0042] (2) The precursor is subjected to oxygen sintering at a sintering temperature of 910°C and a sintering time of 26 hours. After sintering, the resultant is naturally cooled and then crushed and sieved to obtain a lead-based layered oxide material.

[0043] Comparative Example 1

[0044] The general chemical formula of layered oxide materials is: Na 0.89 Cu 0.26 Fe 0.13 Mn 0.61 O2.

[0045] The preparation method of the lead-based layered oxide material comprises the following steps:

[0046] (1) Sodium carbonate, manganese oxide, ferric oxide, and copper oxide are mixed according to the stoichiometric ratio in the general chemical formula, wherein the amount of sodium carbonate added is 1.03 times the theoretical value of the stoichiometric number; anhydrous ethanol is added and ball milled at a ball-to-material ratio of 12:1 and a rotation speed of 250 r / min to obtain a precursor;

[0047] (2) The precursor is subjected to oxygen sintering at a sintering temperature of 910°C and a sintering time of 26 hours. After sintering, the resultant is naturally cooled and then crushed and sieved to obtain a lead-based layered oxide material.

[0048] Example 3

[0049] The general chemical formula of lead-based layered oxide materials is: Na 1.0 Ni 0.29 Fe 0.29 Mn 0.32 Pb 0.10 O2.

[0050] The preparation method of the lead-based layered oxide material comprises the following steps:

[0051] (1) Sodium carbonate, manganese oxide, ferric oxide, lead oxide, and nickel oxide are mixed according to the stoichiometric ratio in the general chemical formula, wherein the amount of sodium carbonate added is 1.03 times the theoretical value of the stoichiometric number; anhydrous ethanol is added and ball milled at a ball-to-material ratio of 18:1 and a rotation speed of 200 r / min to obtain a precursor;

[0052] (2) The precursor is subjected to oxygen sintering at a sintering temperature of 910°C and a sintering time of 26 hours. After sintering, the resultant is naturally cooled and then crushed and sieved to obtain a lead-based layered oxide material.

[0053] Example 4

[0054] The general chemical formula of lead-based layered oxide materials is: Na 1.0 Ni 0.45 Fe 0.20 Mn 0.22 Pb 0.13 O2.

[0055] The preparation method of the lead-based layered oxide material comprises the following steps:

[0056] (1) Sodium carbonate, manganese oxide, ferric oxide, lead oxide, and nickel oxide are mixed according to the stoichiometric ratio in the general chemical formula, wherein the amount of sodium carbonate added is 1.03 times the theoretical value of the stoichiometric number; anhydrous ethanol is added and ball milled at a ball-to-material ratio of 15:1 and a rotation speed of 200 r / min to obtain a precursor;

[0057] (2) The precursor is subjected to oxygen sintering at a sintering temperature of 910°C and a sintering time of 26 hours. After sintering, the resultant is naturally cooled and then crushed and sieved to obtain a lead-based layered oxide material.

[0058] Comparative Example 2:

[0059] The general chemical formula of layered oxide materials is: Na 1.0 Ni 0.40 Fe 0.20 Mn 0.40 O2.

[0060] The preparation method of the lead-based layered oxide material comprises the following steps:

[0061] (1) Sodium carbonate, manganese oxide, ferric oxide, and nickel oxide are mixed according to the stoichiometric ratio in the general chemical formula, wherein the amount of sodium carbonate added is 1.03 times the theoretical value of the stoichiometric number; anhydrous ethanol is added and ball milled at a ball-to-material ratio of 15:1 and a rotation speed of 200 r / min to obtain a precursor;

[0062] (2) The precursor is subjected to oxygen sintering at a sintering temperature of 910°C and a sintering time of 26 hours. After sintering, the resultant is naturally cooled and then crushed and sieved to obtain a lead-based layered oxide material.

[0063] Example 5

[0064] 1. Positive electrode of sodium ion battery

[0065] The lead-based layered oxide materials in Examples 1-4 and Comparative Examples 1-2 were used as positive electrode active materials to prepare positive electrode sheets. 91% of the positive electrode active material, 4% of the conductive carbon black, 5% of the polytetrafluoroethylene (PVDF) and N-methylpyrrolidone (NMP) were mixed by mass, and the positive electrode slurry was prepared by stirring. The positive electrode slurry was then transferred to an aluminum foil by a coating process, and then baked, rolled and die-cut to obtain a positive electrode sheet.

[0066] 2. Sodium-ion batteries

[0067] The aforementioned positive electrode sheets were used to form sodium-ion batteries. The negative electrode sheets used hard carbon as the negative active material. The positive and negative electrode sheets, along with the separator, were stacked to form a semi-finished cell, which was then packaged into a soft-pack battery. After packaging, the battery was baked in an 85°C vacuum oven for 8 hours to remove internal moisture. After liquid injection and pre-sealing, the battery was left for 12 hours. The battery was then charged using a constant current of 0.05C for 30 minutes, 0.2C for 40 minutes, and 0.5C for 30 minutes. The battery was then resealed, left for stabilization, and then recharged to obtain a sodium-ion battery.

[0068] Table 1 Electrochemical performance of sodium ion batteries

[0069]

[0070] As can be seen from Table 1, the present invention adopts the method of doping lead elements, and cooperates with other metal elements, and further limits the molar ratio of each element, which effectively improves the electrochemical properties of the layered sodium ion positive electrode material, while increasing the gram capacity. At the same time, the cycle performance is improved, and the battery 170 cycle capacity retention rate can reach more than 89%. Comparing Comparative Example 1 and Example 2, the molar ratios of the elements of the lead-based layered oxide materials in the two are similar, and lead element doping is not used in Comparative Example 1, resulting in a significant decrease in its cycle retention rate. Similarly, comparing Comparative Example 2 and Example 4, the molar ratios of the elements of the lead-based layered oxide materials in the two are similar, and lead element doping is not used in Comparative Example 2, resulting in a significant decrease in its cycle retention rate. This shows that only under the conditions of the element combination and molar ratio limitation of the present invention can the cycle performance be improved while maintaining a higher gram capacity.

[0071] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A lead-based layered oxide material for sodium ion batteries, characterized in that: The general chemical formula of the lead-based layered oxide material is: Na a T 1-b-c-d Mn b Fe c Pb d O e The lead-based layered oxide material is used as a positive electrode active material for sodium ion batteries; The T is one or a combination of two of the Ni element and the Cu element; the a, b, c, d, and e are molar ratios of the corresponding elements, and 0.70≤a≤1.25, 0.10≤b≤0.45, 0.10≤c≤0.45, 0.01≤d≤0.25, and 1.75≤e≤2.

25.

2. A method for preparing the lead-based layered oxide material for sodium ion batteries according to claim 1, characterized in that: The steps include: (1) Sodium carbonate, manganese oxide, ferric oxide, lead oxide, and T oxide are mixed in a stoichiometric ratio according to the general chemical formula, and a solvent is added to perform ball milling to obtain a precursor; (2) The precursor is subjected to oxygen sintering, and then crushed and sieved to obtain a lead-based layered oxide material.

3. The preparation method according to claim 2, wherein The amount of sodium carbonate added is 1.01 to 1.10 times the theoretical value of the stoichiometric number.

4. The preparation method according to claim 2, wherein The oxygen sintering is as follows: the sintering temperature is 600-950° C., and the sintering time is 10-36 hours.

5. The preparation method according to any one of claims 2 to 4, characterized in that: The solvent is anhydrous ethanol or water.

6. The preparation method according to any one of claims 2 to 4, characterized in that: The ball milling process parameters are: ball-to-material ratio of 10-20:1, and rotation speed of 150-300 r / min.

7. A positive electrode plate for a sodium ion battery, characterized in that: The positive electrode plate includes a current collector and an active material layer bonded to the current collector; the active material layer contains the lead-based layered oxide material as described in claim 1 or the lead-based layered oxide material prepared by the preparation method as described in any one of claims 2-6.

8. A sodium ion battery, characterized in that: The sodium ion battery comprises the positive electrode sheet as claimed in claim 7.

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