O2 type lithium cobalt oxide precursor, preparation method and O2 type lithium cobalt oxide

Abstract

The invention belongs to the technical field of lithium ion batteries, and discloses an O2 type lithium cobaltate precursor, a preparation method and O2 type lithium cobaltate, the O2 type lithium cobaltate precursor is P2 type pre-lithiated sodium cobaltate, the chemical formula of the P2 type pre-lithiated sodium cobaltate is NaxLiyCog-zMzO2, x + y is more than or equal to 0.60 and less than or equal to 0.80, y is more than or equal to 0.02 and less than or equal to 0.20, z is more than or equal to 0 and less than or equal to 0.012, g is more than or equal to 0.99 and less than or equal to 1, and M is at least one of Nb, Mo and Sb; the particle size D50 of the O2 type lithium cobalt oxide precursor material is 3-10 [mu] m, and the specific surface area is 0.35-1.4 m < 2 > / g. The O2 type lithium cobalt oxide precursor provided by the invention is different from conventional P2 type sodium cobalt oxide, P2 type pre-lithiated sodium cobalt oxide is formed through lithium, sodium and cobalt in a specific proportion, so that the ion exchange rate of O2 type lithium cobalt oxide prepared through subsequent ion exchange can be improved, and the residual quantity of sodium ions is effectively reduced.

Description

Technical Field

[0001] This application relates to the field of lithium-ion battery technology, specifically to an O2-type lithium cobalt oxide precursor, its preparation method, and the O2-type lithium cobalt oxide. Background Technology

[0002] Currently, commercially available lithium cobalt oxide has an O3 structure, which is simple to prepare and low in cost, suitable for products in the 4.2–4.50V voltage range. However, at higher voltages, it is prone to irreversible phase transitions from O3 to O1, leading to structural collapse, severe capacity loss, and low cycle retention. In contrast, O2-type lithium cobalt oxide exhibits high phase transition reversibility, showing no significant capacity loss at high voltages (≥4.55V), making it a suitable choice for high-voltage applications. However, the development of O2-type lithium cobalt oxide has been relatively slow, primarily due to the need for ion exchange for preparation, which is difficult to control, resulting in higher costs and a significant gap between expected and actual cycle life. Furthermore, due to the higher application voltages, the materials currently used in battery cells, including current collectors, separators, and electrolytes, exhibit poor stability at high voltages, requiring further development. Nevertheless, with the increasing demand from application sectors, the development and high-end applications of O2-type lithium cobalt oxide have been prioritized, prompting companies to increase investment.

[0003] The preparation of O2-type lithium cobalt oxide first requires the synthesis of P2-type sodium cobalt oxide (molecular formula Na). 0.67 Sodium p2 cobalt oxide (P2 type) was used as a precursor, and then ion exchange was employed to immerse it in a high-concentration lithium-rich solution, resulting in the Na+ reaction. + / Li + The process involves ion exchange to generate O2-type lithium cobalt oxide. However, in actual production, this method suffers from problems such as long ion exchange time and incomplete ion exchange, which leads to high production costs. Furthermore, residual sodium ions can be released during battery charging and discharging, embedding and damaging the interlayer structure of graphite, resulting in cycle degradation. Summary of the Invention

[0004] One of the objectives of this application is to provide an O2-type lithium cobalt oxide precursor, which is a P2-type pre-lithiated sodium cobalt oxide with a specific chemical formula, thereby improving the ion exchange rate of subsequent ion exchange method for preparing O2-type lithium cobalt oxide and reducing the residual amount of sodium ions.

[0005] Another objective of this application is to provide a method for preparing an O2-type lithium cobalt oxide precursor, thereby obtaining a precursor that can improve the ion exchange rate of O2-type lithium cobalt oxide and effectively improve the electrical performance of O2-type lithium cobalt oxide materials.

[0006] Another objective of this application is to provide an O2-type lithium cobalt oxide with a low sodium ion residue, thereby improving its electrical performance during full electric cycling at 4.65V.

[0007] To achieve the above objectives, this application also provides an O2-type lithium cobalt oxide precursor, wherein the O2-type lithium cobalt oxide precursor is a P2-type pre-lithiated sodium cobalt oxide, and the general chemical formula of the P2-type pre-lithiated sodium cobalt oxide is Na. x Li y Co g-z M z O2, wherein 0.60≤x+y≤0.80, 0.02≤y≤0.20, 0≤z≤0.012, 0.99≤g≤1, and M is at least one of Nb, Mo, and Sb; the particle size D50 of the O2-type lithium cobalt oxide precursor material is 3–10 μm, and the specific surface area is 0.35–1.4 m². 2 / g.

[0008] Preferably, the precursor material has a particle size D50 of 4.0–7.0 μm and a specific surface area of ​​0.4–0.8 m². 2 / g.

[0009] More preferably, the precursor material structure belongs to the P63 / mmc space group, with a peak intensity of 5.20≤I(002) / I(100)≤5.80.

[0010] In the technical solution of this application, M is a doping element that improves the ion exchange efficiency in the subsequent step 2. By doping M, the ion exchange efficiency can be improved, thereby reducing production time and cost.

[0011] The P2-type sodium cobalt oxide of this application is pre-doped with a portion of lithium, and the amount of lithium doping is controlled, so that the precursor P2-type pre-lithiated sodium cobalt oxide retains the P2 type while improving the ion exchange rate of the subsequent O2-type lithium cobalt oxide.

[0012] This application also discloses a method for preparing an O2-type lithium cobalt oxide precursor, wherein sodium source, lithium source, cobalt source and M source are mixed evenly and then pre-sintered at a sintering temperature of 350-650°C for 2-6 hours in a dry air or oxygen atmosphere, and then sintered at a sintering temperature of 800-950°C for 10-18 hours. After sintering, P2-type pre-lithiated sodium cobalt oxide is obtained.

[0013] Preferably, the sodium source includes at least one of sodium carbonate, bicarbonate, oxalate, acetate, and hydroxide.

[0014] Preferably, the lithium source includes at least one of lithium carbonate, bicarbonate, oxalate, acetate, and hydroxide.

[0015] Preferably, the cobalt source includes at least one of cobalt tetroxide, cobalt suboxide, cobalt carbonate, cobalt hydroxyl oxide, and cobalt hydroxide.

[0016] Preferably, when M is Nb, the source of M is one or two of niobium pentoxide and lithium niobate; when M is Mo, the source of M is one or two of molybdenum tetroxide, molybdenum dioxide, molybdenum oxide, ammonium molybdate, sodium molybdate, and molybdenum acetate; when the metal M is Sb, the source of M is one of antimony oxide, antimony trioxide, antimony pentoxide, and sodium antimonide.

[0017] This application discloses an O2-type lithium cobalt oxide, which is obtained by converting the above-mentioned O2-type lithium cobalt oxide precursor using an ion exchange method.

[0018] Preferably, the sodium content of the O2-type lithium cobalt oxide is <100ppm.

[0019] More preferably, the sodium content of the O2-type lithium cobalt oxide is <60ppm.

[0020] Preferably, the particle size D50 of the O2-type lithium cobalt oxide is 2.0 to 9.0 μm.

[0021] Preferably, the specific surface area of ​​the O2-type lithium cobalt oxide is 0.3–1.3 m². 2 / g.

[0022] Furthermore, the specific operation of the ion exchange method is as follows: prepare a solution of LiOH:LiCl = 1:1 with a concentration of 5 mol / L, add pre-lithiated sodium cobaltate to the solution, and control the Li... + Na + = 10:1, the solution temperature is controlled at 100℃, and the mixture is stirred continuously for 8-15 hours. After the reaction is completed, the mixture is filtered, washed and dried to obtain O2 type lithium cobalt oxide.

[0023] It should be noted that the aforementioned filtration, washing, and drying are all commonly used technical means in this field, and those skilled in the art can make conventional technical adjustments based on actual output and product demand.

[0024] Preferably, the specific operation of the vacuum filtration is as follows: the solution after the reaction is completed is introduced into a Buchner funnel with filter paper with a pore size of 8-50μm, the vacuum system is activated to put the inside of the tank under negative pressure, thereby accelerating the solid-liquid separation speed and obtaining a filter cake.

[0025] Preferably, the washing process is as follows: after the first filtration is completed, the filter cake is put into deionized water, stirred for 5 minutes, and then the above filtration steps are performed. The washing process is repeated at least 3 times.

[0026] Beneficial effects

[0027] Compared with the prior art, this application provides an O2 type lithium cobalt oxide precursor, which is different from the conventional P2 type sodium cobalt oxide. It forms a P2 type pre-lithiated sodium cobalt oxide by using a specific ratio of lithium, sodium and cobalt, thereby improving the ion exchange rate of subsequent ion exchange preparation of O2 type lithium cobalt oxide and effectively reducing the residual amount of sodium ions. Attached Figure Description

[0028] The present application will be further described below with reference to the accompanying drawings and embodiments;

[0029] Figure 1 This is an XDR image of Embodiment 1 of this application;

[0030] Figure 2 This is an XDR image of Comparative Example 3 of this application;

[0031] Figure 3 This is an XDR image of Comparative Example 4 of this application. Detailed Implementation

[0032] The present application will be further described below with reference to embodiments, but this does not constitute any limitation on the present application. Any limited modifications made within the scope of the claims of the present application shall still be within the scope of the claims of the present application.

[0033] To illustrate the technical content of this application in detail, the following description is provided in conjunction with the embodiments.

[0034] Example 1

[0035] An O2-type lithium cobalt oxide is prepared by the following steps:

[0036] Step 1: Mix 0.31 mol Na₂CO₃, 0.03 mol Li₂CO₃, and 0.333 mol Co₃O₄ evenly, place the mixture in a muffle furnace, and pre-sinter at 600℃ for 3 hours. Then sinter at 900℃ for 12 hours. After sintering, crush the mixture to obtain P₂ type pre-lithiated sodium cobaltate with a particle size of 5.6 μm and a specific surface area of ​​0.646 m². 2 / g, in XRD detection, the structure belongs to the P63 / mmc space group, and the peak intensity I(002) / I(100)=5.435.

[0037] Step 2: Prepare a LiOH:LiCl solution with a concentration of 5 mol / L (1:1 ratio). Add sodium cobaltate to the solution and control the Li... + Na + The ratio of cobalt oxide to carbon dioxide was 10:1, the solution temperature was controlled at 100℃, and stirring was continued for 10 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain O2-type lithium cobalt oxide with a particle size of 5.0 μm and a specific surface area of ​​0.611 m². 2 / g.

[0038] Example 2

[0039] An O2-type lithium cobalt oxide is prepared by the following steps:

[0040] Step 1: Mix 0.31 mol Na₂CO₃, 0.03 mol Li₂CO₃, 0.331 mol Co₃O₄, and 0.001 mol Nb₂O₅ evenly, place the mixture in a muffle furnace, and pre-sinter at 600℃ for 3 hours. Then sinter at 900℃ for 12 hours. After sintering, crush the mixture to obtain modified pre-lithiated P₂ type sodium cobaltate with a particle size of 5.5 μm and a specific surface area of ​​0.652 m². 2 / g, in XRD analysis, the structure belongs to the P63 / mmc space group, with a peak intensity I(002) / I(100)=5.495.

[0041] Step 2: Prepare a LiOH:LiCl solution with a concentration of 5 mol / L (1:1 ratio). Add sodium cobaltate to the solution and control the Li... + Na + The ratio of cobalt oxide to sodium cobalt oxide was 10:1, the solution temperature was controlled at 100℃, and stirring was continued for 10 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain O2-type lithium cobalt oxide with a particle size of 4.8 μm and a specific surface area of ​​0.629 m². 2 / g.

[0042] Example 3

[0043] An O2-type lithium cobalt oxide is prepared by the following steps:

[0044] Step 1: Mix 0.29 mol Na₂CO₃, 0.02 mol LiOH, 0.331 mol Co₃O₄, and 0.002 mol MoO₃ evenly, place the mixture in a muffle furnace, and pre-sinter at 350℃ for 6 hours. Then sinter at 800℃ for 10 hours. After sintering, crush the mixture to obtain modified pre-lithiated P₂ type sodium cobaltate with a particle size of 3.2 μm and a specific surface area of ​​1.387 m². 2 / g, in XRD analysis, the structure belongs to the P63 / mmc space group, with a peak intensity I(002) / I(100)=5.319.

[0045] Step 2: Prepare a LiOH:LiCl solution with a concentration of 5 mol / L (1:1 ratio). Add sodium cobaltate to the solution and control the Li... + Na + The ratio of cobalt oxide to carbon dioxide was 10:1, the solution temperature was controlled at 100℃, and stirring was continued for 10 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain O2-type lithium cobalt oxide with a particle size of 2.1 μm and a specific surface area of ​​1.303 m². 2 / g.

[0046] Example 4

[0047] An O2-type lithium cobalt oxide is prepared by the following steps:

[0048] Step 1: Mix 0.3 mol Na₂CO₃, 0.1 mol Li₂CO₃, 0.331 mol Co₃O₄, and 0.001 mol Sb₂O₃ evenly, place the mixture in a muffle furnace, and pre-sinter at 650℃ for 2 hours. Then sinter at 950℃ for 18 hours. After sintering, crush the mixture to obtain modified pre-lithiated P₂ type sodium cobaltate with a particle size of 9.8 μm and a specific surface area of ​​0.389 m². 2 / g, in XRD analysis, the structure belongs to the P63 / mmc space group, with a peak intensity I(002) / I(100)=5.525.

[0049] Step 2: Prepare a LiOH:LiCl solution with a concentration of 5 mol / L (1:1 ratio). Add sodium cobaltate to the solution and control the Li... + Na + The ratio of cobalt oxide to carbon dioxide was 10:1, the solution temperature was controlled at 100℃, and stirring was continued for 10 hours. After the reaction was completed, the mixture was filtered, washed, and dried to obtain O2-type lithium cobalt oxide with a particle size of 9.0 μm and a specific surface area of ​​0.301 m². 2 / g.

[0050] Comparative Example 1

[0051] The process is largely the same as in Example 1, except that step 1 is modified as follows: 0.34 mol Na₂CO₃ and 0.333 mol Co₃O₄ are mixed evenly, placed in a muffle furnace, and pre-sintered at 600°C for 3 hours, followed by sintering at 900°C for 12 hours. After sintering, the mixture is crushed to obtain P₂ type sodium cobaltate with a particle size of 5.5 μm and a specific surface area of ​​0.653 m². 2 / g, in XRD detection, the structure belongs to the P63 / mmc space group, and the peak intensity I(002) / I(100)=4.545;

[0052] The O2-type lithium cobalt oxide particles have a particle size of 4.9 μm and a specific surface area of ​​0.616 m². 2 / g.

[0053] Comparative Example 2

[0054] The process is largely the same as in Example 1, except that step 1 is modified as follows: 0.335 mol Na₂CO₃, 0.005 mol Li₂CO₃, and 0.333 mol Co₃O₄ are mixed evenly and placed in a muffle furnace for pre-sintering at 600°C for 3 hours, followed by sintering at 900°C for 12 hours. After sintering, the mixture is crushed to obtain P₂ type pre-lithiated sodium cobaltate with a particle size of 5.5 μm and a specific surface area of ​​0.649 m². 2 / g, in XRD detection, the structure belongs to the P63 / mmc space group, and the peak intensity I(002) / I(100)=5.128;

[0055] The O2-type lithium cobalt oxide particles have a particle size of 5.0 μm and a specific surface area of ​​0.614 m². 2 / g.

[0056] Comparative Example 3

[0057] The process is largely the same as in Example 1, except that step 1 is modified as follows: 0.19 mol Na₂CO₃, 0.15 mol Li₂CO₃, and 0.333 mol Co₃O₄ are mixed evenly and placed in a muffle furnace for pre-sintering at 600°C for 3 hours, followed by sintering at 900°C for 12 hours. After sintering, the mixture is crushed to obtain P₂ type pre-lithiated sodium cobaltate with a particle size of 5.6 μm and a specific surface area of ​​0.633 m². 2 / g, in XRD detection, peak intensity I(002) / I(100)=4.115;

[0058] The O2-type lithium cobalt oxide particles have a particle size of 5.1 μm and a specific surface area of ​​0.609 m². 2 / g.

[0059] Comparative Example 4

[0060] The process is largely the same as in Example 1, except that step 1 is modified as follows: 0.34 mol Na₂CO₃, 0.19 mol Li₂CO₃, and 0.333 mol Co₃O₄ are mixed evenly and placed in a muffle furnace for pre-sintering at 600°C for 3 hours, followed by sintering at 900°C for 12 hours. After sintering, the mixture is crushed to obtain pre-lithiated sodium cobaltate with a particle size of 5.8 μm and a specific surface area of ​​0.639 m². 2 / g, in XRD detection, peak intensity I(002) / I(100)=3.448;

[0061] The O2-type lithium cobalt oxide particles have a particle size of 5.2 μm and a specific surface area of ​​0.605 m². 2 / g.

[0062] Performance testing

[0063] I. Detection of Sodium Ion Residue

[0064] The lithium cobalt oxide materials obtained in Examples 1-4 and Comparative Examples 1-4 were subjected to ICP testing to determine their Na content. The results are shown in Table 1.

[0065] Table 1. Results of sodium ion residue in lithium cobalt oxide materials obtained in Examples 1-4 and Comparative Examples 1-4

[0066] <![CDATA[Na + Content (ppm) Example 1 55 Example 2 18 Example 3 19 Example 4 15 Comparative Example 1 27499 Comparative Example 2 24304 Comparative Example 3 50 Comparative Example 4 41641

[0067] According to the results in Table 1:

[0068] According to the data from Examples 1-4, the technical solution of this application can control the sodium residue in the finished lithium cobalt oxide product to below 100 ppm, proving that it has significantly improved the sodium ion exchange rate; among them, Examples 2-4 further reduced the sodium ion residue by doping with element M.

[0069] According to the data comparison between Example 1 and Comparative Example 1, if lithium is not doped to pre-lithiate the P2 type sodium cobalt oxide during the preparation process, the sodium residue will increase significantly. The possible reason is that the ion exchange of the P2 type sodium cobalt oxide is incomplete, and the sodium ions deep inside the particles are not effectively replaced, resulting in an excessively high sodium ion residue in the lithium cobalt oxide material. The pre-lithiation step can be carried out during high-temperature sintering, using the energy of high temperature to pre-embed lithium ions deep inside the particles.

[0070] According to the data comparison between Example 1 and Comparative Example 2, if the amount of lithium doped during the preparation of P2 type sodium cobalt oxide is small, the degree of pre-lithiation is insufficient, which will still lead to incomplete ion exchange of P2 type sodium cobalt oxide, resulting in excessive sodium ion residue in the final lithium cobalt oxide material.

[0071] According to the data comparison between Example 1 and Comparative Example 3, when the total amount of sodium and lithium is within the scope of this application, even if the lithium doping amount is too high, it will not cause a significant change in the residual amount of sodium. This is because the lithium content is increased while the sodium content is reduced, thereby reducing the possibility of incomplete conversion.

[0072] According to the data comparison between Example 1 and Comparative Example 4, even when the amounts of sodium and lithium are increased and exceed the range of this application, a large amount of sodium ions remain. The possible reason is that pre-lithiation may increase the ion exchange rate of sodium within a certain range. However, when the amounts of sodium and lithium exceed the range of this application, lithium and sodium compete, thereby hindering the formation of P2 type pre-lithiated sodium cobalt oxide.

[0073] II. Full Battery Electrical Performance Testing

[0074] The lithium cobalt oxide obtained in Examples 1-4 and Comparative Examples 1-4 were assembled into full cells with graphite as the negative electrode. The cells were subjected to charge-discharge tests. The discharge capacity was tested at 0.1C, and the cells were cycled at 1C for 300 cycles to obtain the capacity retention rate. The results are shown in Table 2.

[0075] Table 2. Performance test results of lithium cobalt oxide batteries obtained in Examples 1-4 and Comparative Examples 1-4

[0076]

[0077] According to the results in Table 2:

[0078] According to the data from Examples 1-4, the proposed technical solution can effectively maintain the full battery's capacity retention rate at over 90% after 300 cycles, and has high 0.1C discharge specific capacity and 1C / 0.1C rate performance.

[0079] According to the data comparison of Example 1 and Comparative Examples 1 and 2, it can be seen that when preparing P2 type sodium cobalt oxide, the absence of lithium doping or the amount of lithium doping is too small, and the pre-lithiation is unsuccessful, which will lead to a decrease in the electrical performance of the full cell. This is mainly reflected in the 300-cycle capacity retention rate. The reason may be that the high sodium residue content, during the battery charge and discharge, sodium ions, because their ionic radius is larger than the graphite interlayer spacing, damage the graphite, resulting in a significant decrease in cycle performance.

[0080] Based on the data from Example 1 and Comparative Example 3, it can be seen that excessive lithium doping during the preparation of P2-type sodium cobalt oxide also leads to a decrease in the electrical performance of the full cell. Although its 0.1C discharge specific capacity is improved compared to Comparative Example 1 and Comparative Example 2, its 1C / 0.1C rate still decreases, and the decrease in the 300-cycle capacity retention rate is more severe than that of Comparative Example 1 and Comparative Example 2. It is speculated that the reason is that because a large amount of lithium carbonate was added during the preparation of the precursor, some O3-type lithium cobalt oxide was generated, so the capacity was higher than that of Comparative Example 1-2, which did not generate O3-type lithium cobalt oxide. However, due to the decrease in sodium content, the content of O2-type lithium cobalt oxide was significantly reduced, resulting in a significant decrease in the 300-cycle capacity retention rate.

[0081] Based on the data from Example 1 and Comparative Example 4, it can be seen that when the amount of sodium and lithium used in Comparative Example 4 exceeds the range of this application, it will lead to a significant decrease in the 300-cycle capacity retention rate. Based on the data in Table 1, it is speculated that this may be because Comparative Example 4 produced a portion of O3-type lithium cobalt oxide.

[0082] III. XDR Inspection

[0083] The materials obtained in Example 1, Comparative Example 3, and Comparative Example 4 were subjected to XDR detection, and the results are as follows: Figures 1-3 As shown;

[0084] in, Figure 1 XDR image of Example 1; Figure 2 This is the XDR plot of Comparative Example 3; Figure 3 This is the XDR image of Comparative Example 4.

[0085] XRD analysis showed that the P2-type pre-lithiated sodium cobaltate structure of Example 1 belongs to the P63 / mmc space group, with peak position 0.43≤(2-Theta(002)) / (2-Theta(100))≤0.45 and peak intensity 5.00≤I(002) / I(104)≤6.50.

[0086] Unlike Comparative Examples 3 and 4, Example 1 of this application only yielded P2-type results and did not generate O3-type lithium cobalt oxide. In conjunction with the above test results, it can be seen that this application improved the conversion rate of O2-type lithium cobalt oxide in subsequent ion exchange through the P2-type pre-lithiated sodium cobalt oxide structure, thereby improving the overall electrical performance.

[0087] Although the total amount of sodium and lithium in Comparative Example 3 was the same as in Example 1, excessive pre-lithiation led to the coexistence of O3 and P2 types, which severely affected the overall electrical performance.

[0088] The embodiments presented herein are merely selected implementations based on combinations of all possible embodiments. The appended claims should not be limited to the embodiments described herein. Some numerical ranges used in the claims include sub-ranges within them, and variations within these ranges should also be covered by the appended claims.

Claims

1. An O2-type lithium cobalt oxide precursor, characterized in that, The O2-type lithium cobalt oxide precursor is a P2-type pre-lithiated sodium cobalt oxide, and the general chemical formula of the P2-type pre-lithiated sodium cobalt oxide is Na. x Li y Co g-z M z O2, wherein 0.60≤x+y≤0.80, 0.02≤y≤0.20, 0≤z≤0.012, 0.99≤g≤1, and M is at least one of Nb, Mo, and Sb; the particle size D50 of the O2-type lithium cobalt oxide precursor material is 3–10 μm, and the specific surface area is 0.35–1.4 m². 2 / g.

2. The O2-type lithium cobalt oxide precursor according to claim 1, characterized in that, The particle size D50 of the O2-type lithium cobalt oxide precursor material is 4.0–7.0 μm.

3. The O2-type lithium cobalt oxide precursor according to claim 1, characterized in that, The specific surface area of ​​the O2-type lithium cobalt oxide precursor material is 0.4–0.8 m². 2 / g.

4. The O2-type lithium cobalt oxide precursor according to claim 1, characterized in that, The structure of the O2-type lithium cobalt oxide precursor material belongs to the P63 / mmc space group, with a peak intensity of 5.20≤I(002) / I(100)≤5.

80.

5. A method for preparing the O2-type lithium cobalt oxide precursor as described in any one of claims 1-4, characterized in that, Sodium source, lithium source, cobalt source and M source are mixed evenly and then pre-sintered at a sintering temperature of 350-650℃ for 2-6 hours in a dry air or oxygen atmosphere, and then sintered at a sintering temperature of 800-950℃ for 10-18 hours. After sintering, P2 type pre-lithiated sodium cobaltate is obtained.

6. An O2-type lithium cobalt oxide, characterized in that, The O2-type lithium cobalt oxide precursor as described in any one of claims 1-4 is obtained by ion exchange.

7. The O2-type lithium cobalt oxide according to claim 6, characterized in that, The specific operation of the ion exchange method is as follows: prepare a solution with a concentration of 5 mol / L and a LiOH:LiCl ratio of 1:1; add pre-lithiated sodium cobaltate to the solution; and control the Li... + Na + = 10:1, the solution temperature is controlled at 100℃, and the mixture is stirred continuously for 8-15 hours. After the reaction is completed, the mixture is filtered, washed and dried to obtain O2 type lithium cobalt oxide.

8. The O2-type lithium cobalt oxide according to claim 6, characterized in that, The sodium content of the O2-type lithium cobalt oxide is <100ppm.

9. The O2-type lithium cobalt oxide according to claim 6, characterized in that, The particle size D50 of the O2-type lithium cobalt oxide is 2–9.0 μm.

10. The O2-type lithium cobalt oxide according to claim 6, characterized in that, The specific surface area of ​​the O2-type lithium cobalt oxide is 0.3–1.3 m². 2 / g.

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