Lithium-containing cathode active materials with m2teo3 endothermic modification and preparation and use in lithium-ion batteries

Abstract

The application belongs to the field of battery materials, and particularly relates to a preparation method of M2TeO3 internal infiltration heat modified lithium-containing positive electrode active material, which comprises mixing lithium-containing positive electrode active material and M2TeO3 and heat modifying at a temperature of 200-800 DEG C to obtain modified positive electrode active material; M in M2TeO3 is at least one of Na, K and Rb. The application also includes the material prepared by the preparation method and application thereof. The internal infiltration heat modification and joint control of parameter conditions can strengthen the high-temperature and low-temperature performance of the modified active material based on the two-phase exchange migration of components, so that the active material is suitable for wide-temperature-range application requirements, and can also effectively improve the tap density and air stability of the material.

Description

Technical Field

[0001] The present invention relates to the field of battery positive electrode materials, and in particular to the field of lithium ion battery positive electrode material modification. Background Art

[0002] To reduce the consumption of non-renewable resources and carbon monoxide emissions, lithium-ion battery research has shifted its focus to high-energy-density batteries. The increasing demands for high energy density, high power density, and thermal stability in lithium-ion batteries highlight the importance of advanced lithium-ion battery technology.

[0003] With the rapid growth of the demand for large reversible capacity, high safety and long-cycle stability of lithium-ion batteries, in recent decades, more and more explorations have focused on the development of high-performance positive electrode materials. At present, lithium-ion battery positive electrode materials such as lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate and ternary materials are limited by the requirements of low specific capacity, high cycle stability and low cost. Although lithium-rich manganese-based materials have high specific capacity and low cost, their poor structural stability and voltage attenuation have hindered their commercialization. In order to solve the above problems, researchers have carried out a series of modification work on lithium-ion battery positive electrode materials, mainly including surface coating, element doping, single crystallization and concentration gradient structure design.

[0004] For example, a patent application document with publication number WO2021167409A1 discloses a positive electrode active material having ultrafine grains and highly oriented primary particles and a lithium secondary battery containing the same, wherein the positive electrode active material includes a material prepared by calcining a lithium compound with a composite metal hydroxide containing any one or more of nickel (Ni), cobalt (Co), manganese (Mn) and aluminum (Al), wherein the heteroatom is added together with any one or more of nickel (Ni), cobalt (Co), manganese (Mn) and aluminum (Al), or added together with the lithium compound before calcination. For another example, the patent application document with publication number WO2021042986A1 discloses a positive electrode active material, which includes a main particle and an oxide coating layer containing the M1 element coated on the outer surface of the main particle, wherein the main particle includes a nickel-containing lithium composite oxide; the bulk phase of the main particle is uniformly doped with the M2 element; the surface layer of the main particle is an outer doping layer doped with the M3 element; the M1 element and the M3 element are each independently selected from one or more of Mg, Al, Ca, Ce, Ti, Zr, Zn, Y and B, and the M2 element includes one or more of Si, Ti, Cr, Mo, V, Ge, Se, Zr, Nb, Ru, Rh, Pd, Sb, Te, Ce and W.

[0005] In summary, although there are some Te doping methods in the existing technology, they are mainly internal doping methods. This solution can improve the performance of the material to a certain extent, but it is difficult to fully exert the function of Te and it is difficult to further optimize the wide temperature range stability and air resistance stability of the active material. Summary of the Invention

[0006] To solve the existing problems, the present invention provides a method for thermally modifying a lithium-containing positive electrode active material (also referred to as a modified active material or modified positive electrode active material in the present invention) by infiltration with M2TeO3, aiming to improve the wide temperature range stability and air resistance stability of the positive electrode material by utilizing the thermal modification method of infiltration with M2TeO3.

[0007] The second object of the present invention is to provide a lithium ion battery positive electrode active material prepared by the method and thermally modified by M2TeO3 infiltration and its application in lithium ion batteries.

[0008] The third object of the present invention is to provide a lithium-ion battery comprising the M2TeO3 endogenously thermally modified lithium-ion battery positive electrode active material, and its positive electrode and positive electrode material.

[0009] A method for preparing a lithium-containing positive electrode active material subjected to thermal modification by infiltration of M2TeO3, comprising mixing the lithium-containing positive electrode active material and M2TeO3 and thermally modifying the mixture at a temperature of 200-800°C to obtain the modified positive electrode active material;

[0010] The M in the M2TeO3 is at least one of Na, K, and Rb.

[0011] The present invention innovatively incorporates M2Te3 as a modifier in conjunction with the lithium-containing positive electrode active material for endogenous thermal modification. This allows for a gradient endogenous infiltration of M and Te from the outside to the inside (from the bulk surface of the active material toward the bulk). This process also facilitates the exchange transfer of Li from the bulk to the surface, where it participates in the construction of the surface modification layer in situ. The combined control of endogenous thermal modification and parameter conditions described in the present invention enhances the high- and low-temperature performance of the modified active material based on the two-phase exchange migration of components, making it suitable for wide-temperature applications. Furthermore, it effectively improves the material's tap density and air stability.

[0012] In the present invention, the lithium-containing positive electrode active material is a positive electrode active material suitable for lithium-ion batteries, for example, it can be a lithium-containing salt of a transition metal, and further can be one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium manganese silicate, lithium iron silicate, lithium iron phosphate, lithium nickel phosphate, lithium cobalt phosphate, high nickel ternary material, and lithium-rich manganese-based positive electrode material.

[0013] In the present invention, the molar ratio of M2TeO3 to the transition metal in the lithium-containing positive electrode active material is 0.01-0.1:1, preferably 0.03-0.05:1.

[0014] Preferably, the lithium-containing positive electrode active material and M2TeO3 are compounded by a dry method or a wet method.

[0015] In the present invention, the atmosphere in the thermal modification stage is an oxygen-containing atmosphere, for example, air, oxygen, or a mixture of oxygen and diluent gas.

[0016] In the present invention, the temperature for thermal modification is 450 to 650°C, and can further be 500 to 600°C.

[0017] In the present invention, the heating rate during the thermal modification stage is 1-10°C / min, preferably 1-3°C / min, and further preferably 1.5-2.5°C / min. Research in the present invention has shown that controlling the temperature at this preferred rate can further improve the interface physicochemical structure of internal permeation and surface exchange, and can reduce interfacial impedance. This helps further improve the structural stability of the material and its cyclic stability over a wide temperature range.

[0018] In the present invention, the heat treatment time is 3 hours or more, preferably 4 to 8 hours.

[0019] After thermal modification and heat preservation, the material is cooled to room temperature to obtain the modified positive electrode active material. The cooling rate is 1-10°C / min, preferably 1-3°C / min, and further preferably 1.5-2.5°C / min. Research in the present invention has shown that controlling the material at this preferred cooling rate can reduce material segregation and interfacial impedance, thereby further improving the structural stability of the material and its cycling stability over a wide temperature range.

[0020] The present invention also provides a lithium-containing positive electrode active material obtained by the preparation method and subjected to thermal modification of M2TeO3 internal infiltration.

[0021] The preparation method of the present invention can give the prepared material special physical and chemical characteristics, and the material prepared by the preparation method can unexpectedly give the modified material excellent high-temperature and low-temperature cycle properties and air resistance stability.

[0022] The present invention also provides a positive electrode material for a lithium ion battery, comprising a positive electrode active material, which comprises the M2TeO3 endogenously thermally modified lithium-containing positive electrode active material of the present invention.

[0023] The positive electrode material of the present invention, except for the modified active material of the present invention, may have conventional components, and the proportions and contents of the components may be reasonably regulated based on conventional principles.

[0024] For example, the positive electrode material further includes a conductive agent and / or a binder.

[0025] In the present invention, in the positive electrode active material, the content of the M2TeO3 thermally modified lithium-containing positive electrode active material is above 50 wt.%.

[0026] The content of the positive electrode active material in the positive electrode material is 60-90 wt.%.

[0027] The present invention also provides a positive electrode of a lithium ion battery, comprising a current collector and a positive electrode material composited on the surface of the current collector, wherein the positive electrode material is the positive electrode material of the present invention.

[0028] The present invention also provides a lithium ion battery comprising the positive electrode of the present invention.

[0029] Beneficial effects

[0030] The present invention innovatively uses M2TeO3 to perform an infiltration thermal modification of lithium-containing positive electrode active materials from the outside in. This optimizes the material's structure and surface based on the dual-phase migration behavior of M, Te, and Li. This enhances the high- and low-temperature performance of the modified active material, making it suitable for wide-temperature applications. Furthermore, it effectively improves the material's tap density and air resistance. Furthermore, by jointly controlling the heating rate and / or cooling rate during the thermal modification phase, the infiltration interface can be further optimized, helping to further enhance the wide-temperature performance and stability of the prepared material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 1 is a comparison chart of the cycle performance of Example 1 and the comparative example; DETAILED DESCRIPTION

[0032] Example 1:

[0033] Step 1:

[0034] The lithium-rich material precursor (such as Mn 0.667 Ni 0.333 (OH)2) was mixed with lithium carbonate, wherein TM:Li=1:1.5, and after being mixed evenly, sintered at 500℃ for 5 hours and then at 900℃ for 15 hours to obtain lithium-rich manganese-based positive electrode material Li 1.5 Mn 0.667 Ni 0.333 O2 (positive electrode active material).

[0035] Step 2:

[0036] 1g of lithium-rich manganese-based cathode material Li 1.5 Mn0.667 Ni 0.333 O2 and sodium tellurite (modifier) ​​were mixed in ethanol with a Te:TM molar ratio of 1:100 (TM refers to the transition metal element in the positive electrode active material). The ethanol was evaporated at 70°C, and the obtained solid powder was sintered in air. The temperature was raised to 600°C at a rate of 2°C / min and kept at this temperature for 5 hours, and then cooled to room temperature at a rate of 5°C / min to obtain the modified material.

[0037] test:

[0038] The modified lithium-rich manganese-based positive electrode material prepared by the above method, acetylene black and PVDF were mixed in a mass ratio of 8:1:1 to form a slurry, which was evenly coated on aluminum foil and cut into positive electrode sheets with a diameter of 12 mm. Lithium metal foil was used as the negative electrode, Celgard 2400 was used as the separator, and 1M LiPF6 EC / DMC (volume ratio 1:1) solution was used as the electrolyte. The CR2016 button cells were assembled in an argon-filled glove box, which is the battery of Example 1.

[0039] Comparative Example 1

[0040] Compared with Example 1, the only difference is that the treatment of step 2 is not performed, and the Li 1.5 Mn 0.667 Ni 0.333 O2 was used as the positive electrode active material, and other operations and parameters were the same as those in Example 1.

[0041] For comparison, pure lithium-rich manganese-based material samples were assembled into CR2016 button cells using the same conditions, which is the battery of Comparative Example 1. The above two batteries were subjected to charge and discharge cycle tests using the same test equipment and test conditions, where the test voltage range was 2~4.7V, and the cycle tests were carried out at 25℃ and 0.5C. Figure 1 After 200 cycles of the battery in Example 1, the stability increased from 78.70% of the battery in Comparative Example 1 to 83.03%, and the cycle performance was significantly improved.

[0042] The modified material (the material prepared in step 2 of Example 1) and the original material (the material prepared in step 1 of Example 1) were placed in a 50°C constant temperature oven and a -30°C constant temperature oven, respectively, for high and low temperature cycling performance testing. The test voltage range was 2-4.7V. In the cycling test at 50°C and 0.5°C, the comparative example 1 could only perform 97 cycles (short circuit). However, the capacity retention rate of the material of Example 1 was 80.47% after 200 stable cycles. In the cycling test at -30°C and 0.5°C, the stability of the battery of Example 1 increased from 71.32% of the comparative example 1 battery to 81.45% after 200 cycles, indicating a significant improvement in high and low temperature performance.

[0043] After exposure of Comparative Example 1 and Example 1 to O2 and CO2 atmospheres (1:1 volume ratio) for different periods of time, the crystallinity and surface morphology of Comparative Example 1 underwent significant changes. Li2O and Li2CO3 phases were generated in the Comparative Example 1 material, respectively. After 24 hours of exposure to O2 and CO2 atmospheres, the initial capacity of the first cycle rapidly decreased from 245.3 mAh / g to 169.4 mAh / g. The crystallinity and structure of Example 1 remained virtually unchanged, demonstrating good air stability. The initial capacity of Example 1 decreased from 249.5 mAh / g to 235.67 mAh / g. Batteries were assembled using the method of Example 1 for the material stored for 24 hours and cycled for 200 cycles at 0.5C / 25°C. The stability of the material after storage in Example 1 increased from 69.28% of that in the Comparative Example 1 battery to 82.55%.

[0044] Example 2:

[0045] Compared with Example 1, the only difference is that the conditions of step 2 are changed. The difference step is: 1g of lithium-rich manganese-based positive electrode material Li 1.5 Mn 0.667 Ni 0.333 O₂ and potassium tellurite were mixed in ethanol at a Te:TM ratio of 0.5:100. The ethanol was evaporated to dryness at 70°C. The resulting solid powder was sintered in air. The temperature was raised to 500°C at a rate of 2°C / min and held for 6 hours. The temperature was then lowered to room temperature at a rate of 5°C / min to obtain a modified material. Other operations, parameters, and tests were the same as in Example 1.

[0046] The results showed that the modified material retained 83.1% of its original properties after 200 cycles at 25°C and 0.5°C, 80.21% after 200 cycles at 50°C and 0.5°C, and 80.78% after 200 cycles at -30°C and 0.5°C. Furthermore, after 24 hours of exposure to O₂ and CO₂, the original properties retained 83.01% after 200 cycles at 25°C and 0.5°C.

[0047] Example 3:

[0048] Compared with Example 2, the only difference is that in step 2, after the heat preservation is completed, the temperature is cooled to room temperature at a rate of 3°C / min to obtain the modified material. Other operations, parameters and tests are the same as those in Example 2.

[0049] The results showed that the retention rate of the modified material was 85.53% after 200 cycles at 25°C, 83.16% after 200 cycles at 50°C and 0.5°C, and 82.95% after 200 cycles at -30°C and 0.5°C.

[0050] It can be seen from Examples 2 and 3 that the process of the present invention, combined with the cooling rate, can further enhance the intraosmotic replacement effect of the material and further enhance the wide temperature performance of the material.

[0051] Example 4:

[0052] Compared with Example 2, the only difference is that the type of positive electrode active material is changed. Specifically, the difference is that 1g of high nickel positive electrode material LiNi 0.8 Co 0.1 Mn 0.1 O2 and sodium tellurite were mixed in ethanol with Te:TM=0.5:100. The ethanol was evaporated to dryness at 70℃. The obtained solid powder was sintered in air and heated to 500℃ at a rate of 2℃ / min for 6h. Then the temperature was cooled to room temperature at a rate of 8℃ / min to obtain the modified material. The retention rate of the modified material after 200 cycles was 86.53%, which was better than the original sample (LiNi 0.8 Co 0.1 Mn 0.1 The retention rate was 85.32% after 200 cycles at 50°C and 0.5°C, and 82.65% after 200 cycles at -30°C and 0.5°C.

[0053] Example 5:

[0054] Compared with Example 2, the only difference is that in step 2, the heating rate in the roasting stage is 5°C / min, and the other operations and parameters are the same as those in Example 2.

[0055] The modified material retained 79.23% of its original material after 200 cycles at 25°C and 0.5°C, 79.01% after 200 cycles at 50°C and 0.5°C, and 78.65% after 200 cycles at -30°C and 0.5°C.

[0056] It can be seen from Examples 2 and 5 that at the preferred heating rate, the wide temperature performance of the prepared material can be further enhanced.

[0057] Comparative Example 2

[0058] Compared with Example 1, the only difference is that lithium tellurite is used as the modifier, and other operations and parameters are the same as Example 1.

[0059] The results showed that the modified material retained 79.35% of its original content after 200 cycles at 25°C and 0.5°C, 70.34% after 200 cycles at 50°C and 0.5°C, and 71.25% after 200 cycles at -30°C and 0.5°C.

[0060] Comparative Example 3

[0061] Compared with Example 1, the only difference is that sodium silicate is used as the modifier (the molar amount of Si is the same as that of Te), and other operations and parameters are the same as those in Example 1.

[0062] The results showed that the modified material retained 80.14% of its original content after 200 cycles at 25°C and 0.5°C, 72.56% after 200 cycles at 50°C and 0.5°C, and 71.15% after 200 cycles at -30°C and 0.5°C.

[0063] Comparative Example 4

[0064] Compared with Example 1, the only difference is that the modifier of step 2 is mixed with the raw materials of step 1, the treatment of step 1 is carried out, and then the temperature treatment of step 2 is carried out, and the modifier is no longer added in step 2. Other operations and parameters are the same as those in Example 1.

[0065] The results showed that the modified material retained 77.95% of its original properties after 200 cycles at 25°C and 0.5°C, 73.21% after 200 cycles at 50°C and 0.5°C, and 74.21% after 200 cycles at -30°C and 0.5°C.

[0066] In summary, the intravasation process described in the present invention can achieve excellent wide-temperature performance. Based on this basic technology, the combined control of the heating rate and the cooling rate can further enhance the intravasation effect, which helps to further enhance the wide-temperature stability and structural stability of the prepared material.

Claims

1. A method for preparing a lithium-containing positive electrode active material by thermally modified M2TeO3 infiltration, characterized in that: The lithium-containing positive electrode active material and M2TeO3 are mixed and thermally modified at a temperature of 200-800°C to obtain a modified positive electrode active material; The M in the M2TeO3 is at least one of Na, K, and Rb.

2. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 1, characterized in that: The lithium-containing positive electrode active material is a positive electrode active material suitable for lithium-ion batteries.

3. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 2, characterized in that: The lithium-containing positive electrode active material is one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium manganese silicate, lithium iron silicate, lithium iron phosphate, lithium nickel phosphate, lithium cobalt phosphate, high nickel ternary material, and lithium-rich manganese-based positive electrode material.

4. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 1, wherein: The molar ratio of the M2TeO3 to the transition metal in the lithium-containing positive electrode active material is 0.01-0.1:

1.

5. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 4, characterized in that: The molar ratio of the M2TeO3 to the transition metal in the lithium-containing positive electrode active material is 0.03-0.05:

1.

6. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 1, characterized in that: The lithium-containing positive electrode active material and M2TeO3 are compounded by a dry method or a wet method.

7. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 1, characterized in that: The atmosphere during the thermal modification stage is an oxygen-containing atmosphere.

8. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 1, characterized in that: The temperature of thermal modification is 450~650℃.

9. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 8, characterized in that: The temperature of thermal modification is 500~600℃.

10. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 1, characterized in that: The heating rate in the thermal modification stage is 1~10℃ / min.

11. The method for preparing the lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 10, characterized in that: The heating rate in the thermal modification stage is 1~3℃ / min.

12. The method for preparing a lithium-containing positive electrode active material subjected to thermal infiltration modification of M2TeO3 according to claim 11, wherein: The heating rate in the thermal modification stage is 1.5~2.5℃ / min.

13. The method for preparing a lithium-containing positive electrode active material subjected to thermal infiltration modification of M2TeO3 according to claim 1, wherein: The heat treatment time is more than 3 hours.

14. The method for preparing a lithium-containing positive electrode active material subjected to thermal infiltration modification of M2TeO3 according to claim 13, wherein: The heat treatment time is 4~8h.

15. The method for preparing a lithium-containing positive electrode active material by thermally modified M2TeO3 infiltration according to claim 1, wherein: After thermal modification and heat preservation, the temperature is lowered to room temperature to obtain the modified positive electrode active material, wherein the cooling rate is 1-10°C / min.

16. The method for preparing a lithium-containing positive electrode active material by thermally modified M2TeO3 infiltration according to claim 15, characterized in that: The cooling rate is 1-3°C / min.

17. The method for preparing a lithium-containing positive electrode active material by thermal infiltration modification of M2TeO3 according to claim 16, characterized in that: The cooling rate is 1.5-2.5°C / min.

18. A lithium-containing positive electrode active material obtained by the preparation method according to any one of claims 1 to 17 and thermally modified by internal infiltration of M2TeO3.

19. A positive electrode material for a lithium ion battery, comprising a positive electrode active material, characterized in that: The positive electrode active material comprises a lithium-containing positive electrode active material that is thermally modified by internal infiltration of M2TeO3 and prepared by the preparation method according to any one of claims 1 to 17.

20. The positive electrode material for a lithium ion battery according to claim 19, wherein The positive electrode material further comprises a conductive agent and / or a binder.

21. A positive electrode of a lithium-ion battery, comprising a current collector and a positive electrode material composited on the surface thereof, characterized in that: The positive electrode material is the positive electrode material according to claim 19 or 20.

22. A lithium ion battery, characterized in that: Comprising the positive electrode according to claim 20.

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