Sodium-ion battery positive electrode layered oxide material and modification method thereof, sodium-ion battery and application thereof

Abstract

The application provides a sodium ion battery positive electrode layered oxide material and a modification method thereof, a sodium ion battery and application thereof, and relates to the technical field of sodium ion batteries, and comprises the following steps: after the positive electrode layered oxide material is soaked in a modification solution, high-temperature sintering is performed, so that the modified sodium ion battery positive electrode layered oxide material is obtained; wherein the modification solution contains a titanium inorganic salt and an organic acid; the temperature of the high-temperature sintering is 650 DEG C-950 DEG C, and the time of the high-temperature sintering is 0.5h-3h. The application solves the technical problems that the sodium battery positive electrode material has poor capacity, poor air stability and low rate in the prior art, and achieves the technical effects that the sodium battery positive electrode material has good ion migration, good air stability and is not easy to be corroded by electrolyte.

Description

Technical Field

[0001] This invention relates to the technical field of sodium-ion batteries, and in particular to a layered oxide material for the positive electrode of a sodium-ion battery and a method for modifying it, as well as sodium-ion batteries and their applications. Background Technology

[0002] With the increasing severity of energy shortages and environmental pollution, the development of sustainable new energy sources has become a key focus of attention and research, and the development of large-scale energy storage technology is receiving increasing attention. Lithium-ion rechargeable batteries, due to their advantages such as high operating voltage, high energy density, long cycle life, and low self-discharge rate, have been widely promoted and applied.

[0003] However, due to the scarcity of lithium resources and the rising price of lithium compounds as electric vehicles become more widespread, the development of new ion-based rechargeable batteries has become a key research focus in recent years. Sodium and lithium belong to the same group and have similar chemical properties. Furthermore, sodium is abundant and inexpensive, making sodium-ion batteries a viable alternative to lithium-ion batteries in energy storage applications.

[0004] Layered oxide materials for sodium-ion battery cathodes possess advantages such as structural stability and the ability to provide the largest possible transport channels for sodium ions. However, they are unstable in air storage, exhibiting capacity decay, increased excess potential, and sodium carbonate formation. Higher iron content produces O3-type materials, which are identified as reacting more strongly with air, leading to sodium dissolution and surface carbonate formation. It has been reported that some materials begin to degrade after varying air storage times, ranging from several hours to several days. During air degradation, sodium carbonate is formed on the particle surface, which is a lattice of Na... + This is the result of a reaction between water molecules and carbon dioxide in the air. Simultaneously, water molecules pass through the Na / H... + Exchange Acceleration Na + Sodium-ion batteries play a crucial role in dissolution from the crystal lattice, leading to the formation of hydrated phases or structural transitions. Therefore, finding innovative strategies to optimize manufacturing processes and minimize air protection costs is essential for improving the commercial viability and widespread adoption of sodium-ion batteries.

[0005] To address the aforementioned problems with layered oxide cathode materials, existing improvement methods primarily involve surface coating. By coating the layered oxides, the cathode material can be isolated from air, reducing side reactions and suppressing alkali formation, thereby optimizing the material's cycle performance, safety performance, and rate performance. Regarding cathode material coating methods, the traditional approach involves solid-phase mixing of the electrode material with nanoparticles. However, this method cannot effectively control the thickness of the nanoparticles coating the cathode material particles and can lead to uneven nanoparticle distribution. Furthermore, already generated alkaline substances remain on the material surface, resulting in an excessively high pH value. This, in turn, causes corrosion, performance degradation, and particle cracking in sodium-ion cathode materials during cycling.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] One of the objectives of this invention is to provide a method for modifying layered oxide materials for sodium-ion battery cathodes, which can solve the technical problems of poor capacity, poor air stability, and low rate capability of sodium-ion battery cathode materials in the prior art, and achieve the technical effects of good ion mobility, good air stability, and resistance to corrosion by electrolyte in sodium-ion battery cathode materials.

[0008] The second objective of this invention is to provide a modified sodium-ion battery cathode layered oxide material with better capacity, good air stability, and high rate performance.

[0009] The third objective of this invention is to provide a sodium-ion battery with good cycle stability and excellent rate performance.

[0010] The fourth objective of this invention is to provide an application of sodium-ion batteries that can achieve outstanding application results.

[0011] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0012] In a first aspect, a method for modifying a layered oxide material for a sodium-ion battery cathode includes the following steps:

[0013] After the positive electrode layered oxide material is immersed in the modification solution, it is then sintered at high temperature to obtain the modified sodium-ion battery positive electrode layered oxide material.

[0014] The modified solution contains titanium inorganic salt and organic acid;

[0015] The high-temperature sintering temperature is 650℃-950℃, and the high-temperature sintering time is 0.5h-3h.

[0016] Furthermore, the titanium inorganic salt includes at least one of titanium oxysulfate, titanium tetrachloride, and titanium tetrafluoride.

[0017] Furthermore, the amount of the titanium inorganic salt is 0.1%-1% of the weight of the positive electrode layered oxide material;

[0018] Preferably, the amount of the titanium inorganic salt is 0.3%-0.75% of the weight of the positive electrode layered oxide material;

[0019] Preferably, the amount of titanium inorganic salt used is 0.3%-0.5% of the weight of the positive electrode layered oxide material.

[0020] Furthermore, the organic acid includes at least one selected from acetic acid, succinic acid, oxalic acid, malonic acid, benzoic acid, phenylacetic acid, formic acid, propionic acid, and oxalic acid.

[0021] Furthermore, the amount of the organic acid used is 0.1%-0.5% of the weight of the positive electrode layered oxide material;

[0022] Preferably, the amount of organic acid used is 0.1%-0.4% of the weight of the positive electrode layered oxide material;

[0023] Preferably, the amount of organic acid used is 0.1%-0.3% of the weight of the positive electrode layered oxide material.

[0024] Furthermore, the solvent of the modified solution includes alcohol;

[0025] Preferably, the alcohol includes at least one selected from methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, isobutanol, sec-butanol, tert-butanol, n-pentanol, sec-pentanol, n-octanol, sec-octanol, and n-hexanol.

[0026] Furthermore, the soaking time is 20 minutes to 1 hour;

[0027] Preferably, the high-temperature sintering temperature is 800℃-950℃, and the high-temperature sintering time is 1h-2h;

[0028] Preferably, the high-temperature sintering temperature is 850℃-950℃, and the high-temperature sintering time is 1.5h-2h;

[0029] Preferably, the high-temperature sintering is followed by a drying step;

[0030] Preferably, the drying temperature is 100℃-120℃, and the drying time is 4h-6h.

[0031] Secondly, a layered oxide material for a sodium-ion battery cathode obtained by the modification method described in any one of the above claims.

[0032] Thirdly, a sodium-ion battery includes the aforementioned sodium-ion battery positive electrode layered oxide material.

[0033] Fourthly, an application of the aforementioned sodium-ion battery in device operation.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] The present invention provides a method for modifying the layered oxide material of the positive electrode in sodium-ion batteries. The method involves immersing the layered oxide material in a modifying solution followed by high-temperature sintering. This process effectively removes the sodium-ion battery positive electrode layered oxide (Na₂O₃) material. X This invention addresses the residual alkali on the surface of sodium-ion battery cathode materials (TIMO2), while also achieving surface coating. This results in excellent ion mobility, good air stability, and resistance to electrolyte corrosion. Specifically, the layered oxide cathode material is immersed in a modification solution. Organic acids neutralize the residual alkali on the material surface, while titanium inorganic salts are evenly distributed around the material. High-temperature sintering then forms a titanium dioxide coating on the material surface. The high-temperature generated titanium dioxide exhibits high stability and high ionic conductivity, thus solving the technical problems of poor capacity, poor air stability, and low rate capability in existing sodium-ion battery cathode materials. Furthermore, the modification method provided by this invention has fewer steps, a simpler process, and a high success rate, making it suitable for large-scale production.

[0036] The modified sodium-ion battery cathode layered oxide material provided by this invention has better capacity, better air stability, and higher rate performance.

[0037] The sodium-ion battery provided by this invention has good cycle stability and excellent rate performance.

[0038] The sodium-ion battery provided by this invention can achieve outstanding application results. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 The XRD pattern of the positive electrode layered oxide material provided in Example 1 of this invention;

[0041] Figure 2 The SEM image of the positive electrode layered oxide material provided in Example 1 of this invention;

[0042] Figure 3 The XRD pattern of the positive electrode layered oxide material provided in Embodiment 2 of the present invention;

[0043] Figure 4 The SEM image of the positive electrode layered oxide material provided in Example 2 of this invention;

[0044] Figure 5 The XRD pattern of the positive electrode layered oxide material provided in Example 3 of this invention;

[0045] Figure 6 The SEM image of the positive electrode layered oxide material provided in Example 3 of this invention;

[0046] Figure 7 This is a comparison chart of the cycle performance obtained from the experimental examples of this invention;

[0047] Figure 8 This is a comparison chart of the rate performance obtained from the experimental examples of this invention. Detailed Implementation

[0048] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] According to a first aspect of the present invention, a method for modifying a layered oxide material for a sodium-ion battery cathode is provided, comprising the following steps:

[0050] After the positive electrode layered oxide material is immersed in the modification solution, it is then sintered at high temperature to obtain the modified sodium-ion battery positive electrode layered oxide material.

[0051] The modified solution contains titanium inorganic salts and organic acids;

[0052] The high-temperature sintering temperature is 650℃-950℃, and the high-temperature sintering time is 0.5h-3h.

[0053] In this invention, a modified solution containing organic acid and titanium inorganic salt is used to soak the positive electrode layered oxide material. While neutralizing the residual alkali on the material surface, titanium inorganic salt can be evenly distributed around the material. Then, through high-temperature sintering, the titanium inorganic salt will generate uniform titanium dioxide on the material surface, thereby achieving surface coating of the material.

[0054] In summary, the modification method provided by this invention not only has fewer operation steps, simpler process, and higher success rate, making it suitable for large-scale production, but also solves the technical problems of poor capacity, poor air stability, and low rate capability of sodium-ion cathode materials in the prior art. It achieves the technical effects of good ion mobility, good air stability, and resistance to corrosion by electrolyte in sodium-ion cathode materials.

[0055] In a preferred embodiment, the titanium inorganic salt includes, but is not limited to, at least one of titanium oxysulfate, titanium tetrachloride, and titanium tetrafluoride; wherein, the amount of titanium inorganic salt can be 0.1%-1% of the weight of the positive electrode layered oxide material, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, but is not limited thereto, and is further preferably 0.3%-0.75%, and even more preferably 0.3%-0.5%.

[0056] The types and amounts of titanium inorganic salts selected in this invention are more conducive to further improving the effect of titanium dioxide coating on the layered oxide material of sodium-ion battery cathode, and are more conducive to further improving the air stability and rate performance of the material.

[0057] In a preferred embodiment, the organic acid includes, but is not limited to, at least one of acetic acid, succinic acid, oxalic acid, malonic acid, benzoic acid, phenylacetic acid, formic acid, propionic acid, and oxalic acid; wherein the amount of organic acid used can be 0.1%-0.5% of the weight of the positive electrode layered oxide material, for example, 0.1%, 0.2%, 0.3%, 0.4%, or 0.5%, but is not limited thereto, and is more preferably 0.1%-0.4%, and even more preferably 0.1%-0.3%.

[0058] The types and amounts of organic acids selected in this invention are sufficient to neutralize residual alkali on the material surface.

[0059] In a preferred embodiment, the solvent used in the modified solution of the present invention includes, but is not limited to, alcohol solvents. Titanium inorganic salts and organic acids have good solubility in alcohols and do not react with each other, while the alcohols do not damage the material itself. Immersing the material in the modified solution can reduce the alkalinity of the material surface and lower the pH value, while uniformly filling the material with titanium inorganic salts. Subsequently, through high-temperature sintering, the alcohol evaporates, and the titanium inorganic salts generate titanium dioxide, which coats the material.

[0060] In a preferred embodiment, the alcohol solvent includes, but is not limited to, at least one of methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, isobutanol, sec-butanol, tert-butanol, n-pentanol, sec-pentanol, n-octanol, sec-octanol, and n-hexanol.

[0061] In this invention, the stirring time of the modified solution can be 20 min-30 min, and the soaking time of the material can be 20 min-30 min; or, the stirring time of the modified solution can be 40 min-1 h, and the soaking time of the material can be 40 min-1 h.

[0062] In this invention, typical but non-limiting temperature conditions for high-temperature sintering are, for example, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, and 950°C; typical but non-limiting time conditions for high-temperature sintering are, for example, 0.5h, 1h, 1.5h, 2h, 2.5h, and 3h.

[0063] In a preferred embodiment, the high-temperature sintering temperature can be 800℃-950℃, and the high-temperature sintering time can be 1h-2h. More preferably, the high-temperature sintering temperature can be 850℃-950℃, and the high-temperature sintering time can be 1.5h-2h.

[0064] In this invention, the high-temperature sintering temperature and time are more conducive to further improving the formation effect of titanium dioxide and its coating effect on the material.

[0065] In a preferred embodiment, a drying step is further included after high-temperature sintering.

[0066] In this invention, the drying temperature can be 100℃-120℃, for example, 100℃, 102℃, 104℃, 106℃, 108℃, 110℃, 115℃, 120℃, but is not limited thereto; the drying time can be 4h-6h, for example, 4h, 5h, 6h, but is not limited thereto.

[0067] According to a second aspect of the present invention, a sodium-ion battery cathode layered oxide material modified by any of the above-described modification methods is provided.

[0068] The modified sodium-ion battery cathode layered oxide material provided by this invention has high specific capacity, as well as excellent cycle performance and rate characteristics.

[0069] According to a third aspect of the present invention, a sodium-ion battery is provided, comprising the above-described sodium-ion battery positive electrode layered oxide material.

[0070] The sodium-ion battery of this invention has good cycle stability, excellent rate performance, and outstanding working performance.

[0071] In addition to the positive electrode sheet containing the positive electrode material of the present invention, the above-mentioned sodium-ion battery further includes an electrolyte and a separator.

[0072] Electrolytes are generally obtained by dissolving sodium salts in organic solvents;

[0073] The sodium salts that can be used include at least one of NaPF6 and Na-ClO4;

[0074] The organic solvents used are mainly anhydrous solvents, including at least one of carbonates (ethylene carbonate, propylene carbonate and diethyl carbonate, etc.), 1,2-dimethoxyethane, tetrahydrofuran and 2-methyltetrahydrofuran;

[0075] Available membranes include at least one of single-layer polypropylene membranes, polyethylene membranes, polyethylene / polypropylene / polyethylene composite membranes, cellulose nonwoven membranes, and glass fiber.

[0076] According to a fourth aspect of the present invention, an application of the sodium-ion battery described above in device driving is provided, which can achieve outstanding application effects.

[0077] 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.

[0078] Example 1

[0079] A method for modifying a layered oxide material for a sodium-ion battery cathode includes the following steps:

[0080] (1) Sodium carbonate, nickel oxide, manganese tetroxide, and copper oxide were sintered in a solid-state process to obtain a positive electrode layered oxide material (Na). 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O2);

[0081] (2) Mix titanium sulfate, ethanol and acetic acid and stir for 40 min to obtain a modified solution;

[0082] The amounts of titanium oxysulfate and acetic acid used in the positive electrode layered oxide material are 0.5 wt% and 0.1 wt%, respectively.

[0083] (3) The positive electrode layered oxide material was immersed in the modified solution for 40 min, then sintered at 950℃ for 2 h, and then placed in a vacuum drying oven for 6 h to obtain the positive electrode layered oxide material coated with titanium dioxide. Its XRD pattern is shown in [reference needed]. Figure 1 Its SEM image is shown below. Figure 2 .

[0084] Example 2

[0085] A method for modifying a layered oxide material for a sodium-ion battery cathode includes the following steps:

[0086] (1) Sodium carbonate, nickel oxide, manganese tetroxide, and copper oxide were sintered in a solid-state process to obtain a positive electrode layered oxide material (Na). 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O2);

[0087] (2) Titanium tetrachloride, ethanol and acetic acid were mixed and stirred for 40 min to obtain a modified solution;

[0088] The amounts of titanium tetrachloride and acetic acid used are 0.5 wt% and 0.1 wt% of the positive electrode layered oxide material, respectively.

[0089] (3) The positive electrode layered oxide material was immersed in the modification solution for 40 min, then sintered at 950℃ for 1.5 h, and subsequently placed in a vacuum drying oven for 6 h to obtain a titanium dioxide-coated positive electrode layered oxide material. Its XRD pattern is shown in [reference needed]. Figure 3 Its SEM image is shown below. Figure 4 .

[0090] Example 3

[0091] A method for modifying a layered oxide material for a sodium-ion battery cathode includes the following steps:

[0092] (1) Sodium carbonate, nickel oxide, ferric oxide, manganese tetroxide, and titanium dioxide were sintered together using a solid-state method to obtain a positive electrode layered oxide material (Na). 0.9 Ni 0.3 Fe 0.3 Mn 0.3 Ti 0.1 O2);

[0093] (2) Mix titanium sulfate, ethanol and acetic acid and stir for 40 min to obtain a modified solution;

[0094] The amounts of titanium oxysulfate and acetic acid used in the positive electrode layered oxide material are 0.5 wt% and 0.1 wt%, respectively.

[0095] (3) The positive electrode layered oxide material was immersed in the modification solution for 40 min, and then sintered at 950℃ for 1.5 h. It was then placed in a vacuum drying oven for 6 h to obtain a titanium dioxide-coated positive electrode layered oxide material. Its XRD pattern is shown below. Figure 5 Its SEM image is shown below. Figure 6 .

[0096] Example 4

[0097] A method for modifying a layered oxide material for a sodium-ion battery cathode includes the following steps:

[0098] (1) Sodium carbonate, nickel oxide, manganese tetroxide, and copper oxide were sintered in a solid-state process to obtain a positive electrode layered oxide material (Na). 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O2);

[0099] (2) Titanium tetrachloride, ethanol and acetic acid were mixed and stirred for 40 min to obtain a modified solution;

[0100] The amounts of titanium tetrachloride and acetic acid used are 0.5 wt% and 0.1 wt% of the positive electrode layered oxide material, respectively.

[0101] (3) The positive electrode layered oxide material was soaked in the modified solution for 40 min, then sintered at 950℃ for 2 h, and then placed in a vacuum drying oven for 4 h to obtain the positive electrode layered oxide material coated with titanium dioxide.

[0102] Example 5

[0103] A method for modifying a layered oxide material for a sodium-ion battery cathode includes the following steps:

[0104] (1) Sodium carbonate, nickel oxide, manganese tetroxide, and copper oxide were sintered in a solid-state process to obtain a positive electrode layered oxide material (Na). 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O2);

[0105] (2) Mix titanium tetrachloride, ethanol and acetic acid and stir for 30 min to obtain a modified solution;

[0106] The amounts of titanium tetrachloride and acetic acid used are 0.5 wt% and 0.1 wt% of the positive electrode layered oxide material, respectively.

[0107] (3) The positive electrode layered oxide material was soaked in the modified solution for 30 min, then sintered at 650℃ for 2 h, and then placed in a vacuum drying oven for 6 h to obtain the positive electrode layered oxide material coated with titanium dioxide.

[0108] Comparative Example 1

[0109] A method for modifying a layered oxide material for a sodium-ion battery cathode includes the following steps:

[0110] (1) Sodium carbonate, nickel oxide, manganese tetroxide, and copper oxide were sintered in a solid-state process to obtain a positive electrode layered oxide material (Na). 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O2);

[0111] (2) Mix ethanol and acetic acid and stir for 40 min to obtain a modified solution;

[0112] The amount of acetic acid used is 0.1 wt% of the positive electrode layered oxide material;

[0113] (3) The positive electrode layered oxide material was soaked in the modified solution for 40 min, then sintered at 950℃ for 2 h, and then placed in a vacuum drying oven for 6 h to obtain the treated positive electrode layered oxide material.

[0114] Comparative Example 2

[0115] A method for modifying a layered oxide material for a sodium-ion battery cathode includes the following steps:

[0116] (1) Sodium carbonate, nickel oxide, manganese tetroxide, and copper oxide were sintered in a solid-state process to obtain a positive electrode layered oxide material (Na). 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O2);

[0117] (2) Mix titanium oxysulfate and ethanol and stir for 30 min to obtain a modified solution;

[0118] The amount of titanium oxysulfate used is 0.5 wt% of the positive electrode layered oxide material;

[0119] (3) The positive electrode layered oxide material was soaked in the modified solution for 30 min, then sintered at 950℃ for 2 h, and then placed in a vacuum drying oven for 6 h to obtain the treated positive electrode layered oxide material.

[0120] Comparative Example 3

[0121] A layered oxide material for sodium-ion battery cathodes is prepared by the following method:

[0122] Sodium carbonate, nickel oxide, manganese tetroxide, and copper oxide were sintered together using a solid-state method to obtain a layered oxide material for the positive electrode (Na). 0.8 Mn 0.55 Ni 0.35 Cu 0.1 O2).

[0123] Experimental Example 1

[0124] The materials prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 were used as positive electrodes, 1 mol / L NaClO4 PC = 100 Vol% with 5% FEC was used as electrolyte, and glass fiber was used as separator to assemble 2025 coin cells.

[0125] The battery performance was tested at 150 mA / g, and the results are shown in Tables 1, 2, and 3. Figure 7 and Figure 8 .exist Figure 7 and Figure 8 In the examples, Example 1 corresponds to sintering at 950℃ for 2 hours with 0.5% titanium salt and 0.1% acid, Comparative Example 1 corresponds to sintering at 950℃ for 2 hours with 0.1% acid, Comparative Example 2 corresponds to sintering at 950℃ for 2 hours with 0.5% titanium salt, and Comparative Example 3 corresponds to NMNCu 0.1%.

[0126] Table 1 Cyclic Comparison Chart

[0127]

[0128] Table 2 Comparison Chart of Multipliers

[0129]

[0130] Table 3 pH value comparison chart

[0131] pH value Example 1 11.79 Comparative Example 1 11.84 Comparative Example 2 12.08 Comparative Example 3 12.11

[0132] Depend on Figure 7 It can be seen that the battery's capacity at 1C is 119.5 mAh / g (compared to 116.8 mAh / g in Comparative Example 1, 114.6 mAh / g in Comparative Example 2, and 110.6 mAh / g in Comparative Example 3), and the capacity is still 115.37 mAh / g after 130 cycles (compared to 102.07 mAh / g in Comparative Example 1, 95.72 mAh / g in Comparative Example 2, and 92.16 mAh / g in Comparative Example 3), indicating that it has very good cycle stability.

[0133] Depend on Figure 8 It can be seen that the battery capacity reaches 158.1 mAh / g at 0.1C (compared to 156 mAh / g in Comparative Example 1, 154.2 mAh / g in Comparative Example 2, and 151.4 mAh / g in Comparative Example 3), and 74.9 mAh / g at 6C (compared to 70.74 mAh / g in Comparative Example 1, 67.57 mAh / g in Comparative Example 2, and 63.68 mAh / g in Comparative Example 3), indicating that it has very good rate performance.

[0134] In summary, this invention utilizes a mixed solution of titanium inorganic salt, organic acid, and alcohol to soak the positive electrode layered oxide, neutralizing residual alkali on the material surface and uniformly distributing titanium inorganic salt around the material. Then, the titanium inorganic salt is used at high temperature to generate uniform titanium dioxide, resulting in a positive electrode layered oxide material uniformly coated with titanium dioxide. This invention not only solves the problem of residual alkali on the surface of the positive electrode layered oxide material but also coats the material surface with a uniform, highly ionicly conductive titanium dioxide protective film, thereby maintaining the cycle performance of the layered material and improving its rate performance and specific capacity to meet the practical requirements of sodium-ion batteries.

[0135] 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 therein. Such 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 method for modifying a layered oxide material for a sodium-ion battery cathode, characterized in that, Includes the following steps: After the positive electrode layered oxide material is immersed in the modification solution, it is then sintered at high temperature to obtain the modified sodium-ion battery positive electrode layered oxide material. The modified solution contains titanium inorganic salt and organic acid; The high-temperature sintering temperature is 650℃-950℃, and the high-temperature sintering time is 0.5h-3h.

2. The modification method according to claim 1, characterized in that, The titanium inorganic salt includes at least one of titanium oxysulfate, titanium tetrachloride, and titanium tetrafluoride.

3. The modification method according to claim 2, characterized in that, The amount of titanium inorganic salt used is 0.1%-1% of the weight of the positive electrode layered oxide material.

4. The modification method according to claim 2, characterized in that, The amount of titanium inorganic salt used is 0.3%-0.75% of the weight of the positive electrode layered oxide material.

5. The modification method according to claim 2, characterized in that, The amount of titanium inorganic salt used is 0.3%-0.5% of the weight of the positive electrode layered oxide material.

6. The modification method according to claim 1, characterized in that, The organic acid includes at least one of acetic acid, succinic acid, oxalic acid, malonic acid, benzoic acid, phenylacetic acid, formic acid, propionic acid, and oxalic acid.

7. The modification method according to claim 6, characterized in that, The amount of organic acid used is 0.1%-0.5% of the weight of the positive electrode layered oxide material.

8. The modification method according to claim 6, characterized in that, The amount of organic acid used is 0.1%-0.4% of the weight of the positive electrode layered oxide material.

9. The modification method according to claim 6, characterized in that, The amount of organic acid used is 0.1%-0.3% of the weight of the positive electrode layered oxide material.

10. The modification method according to any one of claims 1-9, characterized in that, The solvent of the modified solution includes alcohol; The alcohols include at least one of methanol, ethanol, propanol, isopropanol, butanol, ethylene glycol, isobutanol, sec-butanol, tert-butanol, n-pentanol, sec-pentanol, n-octanol, sec-octanol, and n-hexanol.

11. The modification method according to any one of claims 1-9, characterized in that, The soaking time is 20 minutes to 1 hour.

12. The modification method according to any one of claims 1-9, characterized in that, The high-temperature sintering temperature is 800℃-950℃, and the high-temperature sintering time is 1h-2h.

13. The modification method according to any one of claims 1-9, characterized in that, The high-temperature sintering temperature is 850℃-950℃, and the high-temperature sintering time is 1.5h-2h.

14. The modification method according to any one of claims 1-9, characterized in that, The high-temperature sintering process also includes a drying step. The drying temperature is 100℃-120℃, and the drying time is 4h-6h.

15. A layered oxide material for sodium-ion battery cathodes modified by the modification method according to any one of claims 1-14.

16. A sodium-ion battery, characterized in that, Including the sodium-ion battery cathode layered oxide material as described in claim 15.

17. The application of the sodium-ion battery of claim 16 in device driving.

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