Lead-containing positive electrode material and preparation method thereof, positive electrode, sodium ion battery and preparation method of sodium ion battery

Abstract

The invention discloses a lead-containing positive electrode material and a preparation method thereof, and a positive electrode and a sodium ion battery adopting the lead-containing positive electrode material and a preparation method thereof. The lead-containing positive electrode material disclosed by the invention has the composition as shown in a formula I: NaxPbaMbOy (formula I), wherein M is a transition metal element; wherein 0.1 < = x < = 1.0, 0.05 < = a < = 0.6, 0.05 < = b < = 0.9, and 2 < = y < = 4. When the positive electrode material is used for preparing the sodium ion battery, the capacity, the cycle life and the energy density of the battery can be improved, and the performance of the battery in high-power application can be improved.

Description

Technical Field

[0001] This invention relates to the field of batteries, and in particular to a lead-containing cathode material and its preparation method, as well as a cathode and sodium-ion battery using the cathode material. Background Technology

[0002] Sodium-ion batteries, as a potential post-lithium-ion battery technology, have attracted considerable attention due to their advantages such as low cost, wide geographical distribution of sodium resources, high safety, and environmental friendliness. While sodium-ion batteries possess certain advantages, some problems have also emerged in practical applications. The larger radius of sodium ions compared to lithium ions makes the cathode material prone to fission during charging and discharging, leading to a decline in battery performance. Repeated sodium-ion insertion / extraction alters the lattice structure of the electrode material, causing mechanical stress and volume changes, resulting in particle breakage and active material shedding, reducing battery capacity and cycle life. Unpredictable defective phase transitions of sodium ions during charging further degrade battery charging and discharging efficiency, threatening energy density. Moreover, most existing sodium-ion cathode materials sacrifice rate performance while increasing energy density, resulting in poor performance in high-power applications.

[0003] Sodium-ion batteries do face some challenges and problems in their development, and it is urgent to solve these problems by improving the cathode material, thereby improving the performance and stability of sodium-ion batteries and promoting their application and development in more fields. Summary of the Invention

[0004] To address the problems existing in current cathode materials containing transition metal oxides, this invention provides a lead-containing cathode material and its preparation method, as well as a cathode and sodium-ion battery using this cathode material. Sodium-ion batteries prepared using the cathode material of this invention can improve battery capacity, cycle life, energy density, and performance in high-power applications.

[0005] To achieve the above-mentioned objectives of the present invention, a first aspect of the present invention provides a lead-containing cathode material having a composition shown in Formula I: Na x Pb a M b O y (Formula I); where M is a transition metal element, and 0.1≤x≤1.0, 0.05≤a≤0.6, 0.05≤b≤0.9, 2≤y≤4. In this invention, the unique chemical properties and electrochemical stability of lead (Pb), along with other transition metal elements, enable synergistic effects, significantly improving the capacity retention, electrochemical stability, and high-rate performance of sodium-ion batteries. This cathode material not only optimizes the structural stability of the material but also enhances the sodium-ion insertion / extraction efficiency, extending the battery's lifespan.

[0006] According to some embodiments of the present invention, the Pb content is not less than 20 mol%, preferably 20-50 mol%, and more preferably 25-40 mol%. In this invention, Pb possesses unique ionic radius and chemical stability, and synergistically with other transition metal elements, improves the interlayer spacing and electrochemical stability of the material, solving the structural collapse and side reaction problems of traditional cathode materials under high voltage and high rate conditions. By doping into the layered structure, the diffusion path of sodium ions is optimized, enhancing the cycle stability of the material.

[0007] According to some embodiments of the present invention, M is selected from at least two of Ni, Co, Fe, Cu, Mn, Ti, Zn, and Cr; preferably, M contains Co and Ni. In the present invention, b is the sum of all transition metals of M. For example, when M is Co and Ni, then b is the sum of Co and Ni.

[0008] According to some embodiments of the present invention, the molar ratio of Pb to Ni is 1:0.2-1.2. In the present invention, at a specific molar ratio of Pb to Ni, the synergistic effect can be more fully exerted, resulting in superior performance of the cathode material.

[0009] According to some embodiments of the present invention, the molar ratio of Pb to Co is 1:0.2-1.2. In the present invention, the synergistic effect can be more fully exerted at a specific molar ratio of Pb to Co.

[0010] According to some embodiments of the present invention, the molar ratio of Ni to Co is 1:0.5-1.5.

[0011] According to some embodiments of the present invention, the molar ratio of Na to Pb is 1:0.5-2.0.

[0012] According to some embodiments of the present invention, the positive electrode material has a layered structure.

[0013] In this invention, the morphology of the cathode material can be tested using conventional characterization methods in the art, such as SEM, TEM, or XRD.

[0014] According to some embodiments of the present invention, the XRD pattern of the cathode material has a characteristic strong diffraction peak at a position of 18°.

[0015] The second aspect of the present invention provides a method for preparing the lead-containing cathode material described above, comprising: mixing a sodium source, a lead source, and an M source in an oxygen-containing atmosphere, followed by calcination and cooling.

[0016] According to some embodiments of the present invention, the calcination conditions include: a temperature of 850-900°C and a time of 10-20 hours.

[0017] According to some embodiments of the present invention, the cooling conditions include cooling from the melting temperature to 20-25°C at a cooling rate of 5-10°C / h.

[0018] According to some embodiments of the present invention, the method further includes ball milling; preferably, ball milling is performed to 200-500 nm.

[0019] According to some embodiments of the present invention, the lead source is a lead salt and / or lead oxide, preferably the lead source is selected from one or more of lead oxide, lead chloride, lead nitrate, and lead acetate.

[0020] According to some embodiments of the present invention, the M source is a salt of M and / or an oxide of M, wherein the M source is selected from one or more of nickel oxide, nickel chloride, nickel nitrate, nickel sulfate, cobalt oxide, cobalt chloride, cobalt nitrate, cobalt sulfate, copper chloride, manganese chloride, and ferric chloride. In the present invention, M is selected from, but not limited to, at least two of Ni, Co, Fe, Cu, Mn, Ti, Zn, and Cr; preferably, the M contains Co and Ni. In a preferred embodiment, the Ni source is, for example, but not limited to, one or more of nickel oxide, nickel carbonate, nickel nitrate, and nickel sulfate. In a preferred embodiment, the Co source is, for example, but not limited to, one or more of cobalt oxide, cobalt carbonate, cobalt nitrate, and cobalt sulfate.

[0021] According to some embodiments of the present invention, the sodium source is a sodium salt, preferably selected from one or more of sodium carbonate, sodium chloride, and sodium nitrate.

[0022] According to some embodiments of the present invention, the amounts of sodium source, lead source, and M source satisfy n(Na):n(Pb):n(M) = x:a:b. In the present invention, the amounts of sodium source, lead source, and M source satisfy that the resulting cathode material has the composition shown in Formula I: Na x Pb a M b O y (Formula I); where M is a transition metal element, and 0.1≤x≤1.0, 0.05≤a≤0.6, 0.05≤b≤0.3, 2≤y≤4. In this invention, b is the sum of all M transition metals. For example, when M is Co and Ni, then b is the sum of Co and Ni.

[0023] According to some embodiments of the present invention, the oxygen-containing atmosphere may be oxygen or air.

[0024] A third aspect of the present invention provides a positive electrode comprising the lead-containing positive electrode material described above.

[0025] The fourth aspect of the present invention provides a method for preparing the above-mentioned positive electrode, comprising: coating the above-mentioned lead-containing positive electrode material onto a current collector to obtain a positive electrode.

[0026] The fifth aspect of the present invention provides a sodium-ion battery, comprising the above-described positive electrode, separator, electrolyte and negative electrode.

[0027] Beneficial effects of the present invention

[0028] (1) This invention addresses the shortcomings of existing layered transition metal oxide materials by proposing a lead-containing layered transition metal oxide sodium-ion battery cathode material. By introducing lead (Pb) into the material, and through its synergy with other transition metal elements, the unique ionic radius and chemical stability of lead, along with the composite system formed by lead and other transition metals, improve the interlayer spacing and electrochemical stability of the material, thus solving the structural collapse and side reaction problems of traditional cathode materials under high voltage and high rate conditions.

[0029] (2) The cathode material and preparation method of the present invention are subjected to Pb, Ni and Co oxide coating treatment on the surface of the material to improve its surface stability and corrosion resistance.

[0030] (3) The lead-containing layered material of the present invention exhibits excellent structural stability and capacity retention during long-term charge-discharge cycles, with a capacity retention rate of up to 90% after 500 cycles. The introduction of lead significantly reduces side reactions in the high-voltage range, enabling the material to operate stably within a voltage range of 2.0V to 4.2V, thereby improving the energy density of the battery. At a 5C rate, the discharge specific capacity of this material exceeds 85% in preferred conditions, demonstrating excellent performance under high-power conditions. Detailed Implementation

[0031] In the following technical description, for ease of explanation, numerous details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be practiced without these details.

[0032] The terms "first," "second," etc., used in the specification and claims of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0033] The present invention will be further illustrated by the following examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or purchased directly from the market.

[0034] Example 1

[0035] PbO, NiO, and CoO were mixed in air, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, PbO, NiO, and CoO satisfied the ratio n(Na):n(Pb):n(Ni):n(Co) = 0.6:0.3:0.35:0.35. The mixture was calcined at 900℃ for 12 hours, then cooled to 25℃ at a rate of 5℃ / h, and ball-milled to produce a 200nm nanoscale lead-containing cathode material. 0.6 Pb 0.3 Ni 0.35 Co 0.35 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 18°.

[0036] Example 2

[0037] PbO, NiO, and CoO were mixed in air, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, PbO, NiO, and CoO satisfied the ratio n(Na):n(Pb):n(Ni):n(Co) = 0.6:0.6:0.2:0.2. The mixture was calcined at 900℃ for 12 hours, then cooled to 25℃ at a rate of 5℃ / h and ball-milled to produce a 200nm nanoscale lead-containing cathode material. 0.6 Pb 0.6 Ni 0.2 Co 0.2 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 18.1°.

[0038] Example 3

[0039] PbO, NiO, and CoO were mixed in air, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, PbO, NiO, and CoO satisfied the ratio n(Na):n(Pb):n(Ni):n(Co) = 0.4:0.6:0.2:0.2. The mixture was calcined at 900℃ for 12 hours, then cooled to 25℃ at a rate of 5℃ / h and ball-milled to produce a 200nm nanoscale lead-containing cathode material. 0.4 Pb 0.6 Ni 0.2 Co 0.2 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 18.5°.

[0040] Example 4

[0041] PbO, NiO, and CoO were mixed in air, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, PbO, NiO, and CoO satisfied the ratio n(Na):n(Pb):n(Ni):n(Co) = 0.6:0.1:0.4:0.5. The mixture was calcined at 900℃ for 12 hours, then cooled to 25℃ at a rate of 5℃ / h and ball-milled to produce a 200nm nanoscale lead-containing cathode material. 0.6 Pb 0.1 Ni 0.4 Co 0.5 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 18.1°.

[0042] Example 5

[0043] PbCl2, Ni(NO3)2·6H2O, and Co(NO3)2·6H2O were mixed in air, and then an appropriate amount of Na2CO3 was added. The amounts of Na2CO3, PbCl2, Ni(NO3)2·6H2O, and Co(NO3)2·6H2O satisfied the ratio n(Na):n(Pb):n(Ni):n(Co) = 0.6:0.6:0.2:0.2. The mixture was calcined at 900℃ for 12 hours, then cooled to 25℃ at a rate of 5℃ / h and ball-milled to produce a 200nm nanoscale lead-containing cathode material. 0.6 Pb 0.6 Ni 0.2 Co 0.2 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 18.5°.

[0044] Example 6

[0045] PbO, NiO, and CoO were mixed in an air atmosphere, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, PbO, NiO, and CoO satisfied the ratio n(Na):n(Pb):n(Ni):n(Co) = 0.6:0.3:0.35:0.35. The mixture was calcined at 850℃ for 14 hours, then cooled to 25℃ at a rate of 5℃ / h and ball-milled to produce a 200nm nanoscale lead-containing cathode material. 0.6 Pb 0.3 Ni 0.35 Co 0.35 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 18.5°.

[0046] Comparative Example 1

[0047] The method is the same as in Example 1, except that PbO is not used, that is:

[0048] NiO and CoO were mixed in air, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, NiO, and CoO satisfied the ratio n(Na):n(Ni):n(Co) = 0.6:0.35:0.35. The mixture was then calcined at 900℃ for 12 hours, followed by cooling to 25℃ at a rate of 5℃ / h, and ball milling to produce a 200nm nanoscale cathode material. 0.6 Ni 0.35 Co 0.35 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 19.5°.

[0049] Comparative Example 2

[0050] The method is the same as in Example 1, except that NiO is not used, that is:

[0051] PbO and CoO were mixed in air, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, PbO, and CoO satisfied the ratio n(Na):n(Pb):n(Co) = 0.6:0.3:0.35. The mixture was calcined at 900℃ for 12 hours, then cooled to 25℃ at a rate of 5℃ / h and ball-milled to produce a 200nm nanoscale cathode material. 0.6 Pb 0.3 Co 0.35 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 19.2°.

[0052] Comparative Example 3

[0053] The method is the same as in Example 1, except that CoO is not used, i.e.:

[0054] PbO and NiO were mixed in air, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, PbO, and NiO satisfied the ratio n(Na):n(Pb):n(Ni) = 0.6:0.3:0.35. The mixture was then calcined at 900℃ for 12 hours, followed by cooling to 25℃ at a rate of 5℃ / h, and ball milling to produce a 200nm nanoscale cathode material. 0.6 Pb 0.3 Ni 0.35 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 19.0°.

[0055] Comparative Example 4

[0056] PbO, NiO, and CoO were mixed in an air atmosphere, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, PbO, NiO, and CoO satisfied the ratio n(Na):n(Pb):n(Ni):n(Co) = 0.6:0.01:0.35:0.35. The mixture was then calcined at 900℃ for 12 hours, followed by cooling to 25℃ at a rate of 5℃ / h, and ball milling to produce a 200nm nanoscale lead-containing cathode material. 0.6 Pb 0.01 Ni 0.35 Co 0.35 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 18°.

[0057] Comparative Example 5

[0058] PbO, NiO, and CoO were mixed in air, and then an appropriate amount of Na₂CO₃ was added, wherein the amounts of Na₂CO₃, PbO, NiO, and CoO satisfied the ratio n(Na):n(Pb):n(Ni):n(Co) = 0.6:0.8:0.35:0.35. The mixture was calcined at 900℃ for 12 hours, then cooled to 25℃ at a rate of 5℃ / h and ball-milled to produce a 200nm nanoscale lead-containing cathode material. 0.6 Pb 0.8 Ni 0.35 Co 0.35 O2. The XRD pattern of the cathode material shows a characteristic strong diffraction peak at a position of 18°.

[0059] Test case

[0060] The positive electrode materials obtained in the examples and comparative examples were coated on aluminum current collectors to obtain positive electrodes, which were then assembled with PP (polypropylene) separators, 1M NaPF6 / EC+DEC (electrolyte ratio of 1:1) electrolyte and graphite negative electrode to obtain batteries.

[0061] The assembled battery was subjected to charge-discharge cycle tests. At room temperature, the battery test system was used to perform charge-discharge cycle tests to test the initial battery capacity, the battery capacity after 500 cycles, the capacity retention rate in the voltage range of 2.0V-4.2V, and the discharge capacity at 5C rate. The results are shown in Table 1.

[0062] Table 1

[0063]

[0064]

[0065] As shown in Table 1, the lead-containing layered material of this invention exhibits excellent structural stability and capacity retention during long-term charge-discharge cycles, with a capacity retention rate as high as 90% after 500 cycles. The introduction of lead significantly reduces side reactions in the high-voltage range, enabling the material to operate stably within a voltage range of 2.0V to 4.2V, thereby improving the energy density of the battery. At a 5C rate, the material retains over 85% of its discharge specific capacity, demonstrating excellent performance under high-power conditions.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lead-containing cathode material, characterized in that, The cathode material has the following formula I composition: Na x Pb a M b O y (Formula I), where M is a transition metal element; Wherein, 0.1≤x≤1.0, 0.05≤a≤0.6, 0.05≤b≤0.9, and 2≤y≤4.

2. The lead-containing cathode material according to claim 1, characterized in that, The content of Pb is not less than 20 mol%, preferably 20-50 mol%, and more preferably 25-40 mol%.

3. The lead-containing cathode material according to claim 1 or 2, characterized in that, The M is selected from at least two of Ni, Co, Fe, Cu, Mn, Ti, Zn, and Cr; preferably, the M contains Co and Ni; Preferably, the molar ratio of Pb to Ni is 1:0.2-1.2; Preferably, the molar ratio of Pb to Co is 1:0.2-1.2; Preferably, the molar ratio of Ni to Co is 1:0.5-1.5; Preferably, the molar ratio of Na to Pb is 1:0.5-2.

0.

4. The lead-containing cathode material according to any one of claims 1-3, characterized in that, The cathode material has a layered structure; Preferably, the XRD pattern of the cathode material shows a diffraction peak at 18°.

5. A method for preparing the lead-containing cathode material according to any one of claims 1-4, comprising: In an oxygen-containing atmosphere, sodium source, lead source, and M source are mixed, then calcined and cooled.

6. The preparation method according to claim 5, characterized in that, The calcination conditions include: a temperature of 850-900℃ and a time of 10-20h; And / or, the cooling conditions include: cooling from the melting temperature to 20-25°C at a cooling rate of 5-10°C / h; And / or, the method further includes ball milling after cooling; preferably, ball milling to 200-500 nm.

7. The preparation method according to claim 5 or 6, characterized in that, The lead source is a lead salt and / or lead oxide, preferably selected from one or more of lead oxide, lead chloride, lead nitrate, and lead acetate; and / or, The M source is an M salt and / or an oxide of M, preferably selected from one or more of nickel oxide, nickel chloride, nickel nitrate, nickel sulfate, cobalt oxide, cobalt chloride, cobalt nitrate, cobalt sulfate, copper chloride, manganese chloride, and ferric chloride; and / or, The sodium source is a sodium salt, preferably selected from one or more of sodium carbonate, sodium chloride, and sodium nitrate; and / or, The amounts of sodium source, lead source and M source satisfy n(Na):n(Pb):n(M)=x:a:b.

8. A positive electrode comprising the lead-containing positive electrode material according to any one of claims 1-4.

9. The method for preparing the positive electrode according to claim 8, comprising: The lead-containing positive electrode material according to any one of claims 1-4 is coated on the current collector to obtain a positive electrode.

10. A sodium-ion battery comprising the positive electrode, separator, electrolyte, and negative electrode as described in claim 9.

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