Cathode material, method of manufacturing the same, and lithium-ion battery

Abstract

The present invention provides a cobalt-free and nickel-free cathode material, a method for manufacturing the same, and a battery. The manufacturing method comprises a step of manufacturing a cobalt-free and nickel-free matrix material by mixing and reacting a cobalt-free and nickel-free matrix material, a lithium source, and a divalent manganese compound to manufacture the cobalt-free and nickel-free cathode material. By adding a divalent manganese compound, the formation of layered LiMnO2 and spinel LiMn2O4 is suppressed and the formation of layered Li2MnO3 is promoted, thereby improving the cycle performance of the material.

Description

Technology Field

[0001] The present invention relates to the field of battery technology, for example, to cobalt-free and nickel-free cathode materials, a method for manufacturing the same, and a battery. Background Technology

[0002] With the development of the new energy market, ternary cathode materials are receiving significant attention due to their advantages, such as high energy density, high cycle performance, and high safety. While ternary materials like NCM523 and NCM622, which are currently undergoing large-scale commercialization in the power market, can meet the demand for electric vehicles to some extent, improvements in driving range and safety performance are still needed. Furthermore, the prices of cobalt and nickel elements contained in NCM are continuously rising, increasing battery costs, and cobalt metal is prone to causing harm to the environment. The problem to be solved

[0003] The following is an overview of the subject matter described in detail in this specification, and such overview is not intended to limit the cobalt-free and nickel-free cathode materials, methods for manufacturing the same, and batteries provided in the present invention. means of solving the problem

[0004] One embodiment of the present invention provides a method for manufacturing a cobalt-free and nickel-free cathode material, wherein the manufacturing method includes a step of manufacturing a cobalt-free and nickel-free matrix material by mixing and reacting a cobalt-free and nickel-free matrix material, a lithium source, and a divalent manganese compound to manufacture a cobalt-free and nickel-free cathode material.

[0005] In one embodiment provided by the present invention, by adding a divalent manganese compound during the manufacturing process, the formation of layered LiMnO2 and spinel LiMn2O4 is suppressed and the formation of Li2MnO3 is promoted during the cycling process, thereby Mn 3+It effectively prevents the material cycle performance from deteriorating due to capacity loss in layered LiMnO2 and spinel Li2MnO4 caused by the Jahn-Teller effect of Li2MnO4 during the disproportionation reaction and charge / discharge process, and the layered structure of Li2MnO3 effectively improves cycle performance and has the characteristics of a simple manufacturing process, low cost, low contamination, and excellent cycle performance.

[0006] In one embodiment provided in the present invention, the general formula of the cobalt-free and nickel-free matrix material is Na x Li y Mn 0.75 O2, and in the above equation, 0.8≤x≤1, 0≤y≤0.35, for example, x is 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.94, 0.96, 0.98 or 1.00, etc., and y is 0, 0.03, 0.06, 0.09, 0.12, 0.15, 0.18, 0.21, 0.24, 0.27, 0.30, 0.33 or 0.35, etc.

[0007] In one embodiment, the lithium source comprises one or more combinations of lithium carbonate, lithium hydroxide, lithium chloride, or lithium fluoride.

[0008] In one embodiment, the method for manufacturing the cobalt-free and nickel-free matrix material comprises the step of mixing a lithium salt, a manganese salt, and a sodium salt, wherein the molar ratio of the lithium element in the lithium salt, the sodium element in the sodium salt, and the manganese element in the manganese salt is (0.2~0.3):(0.9~1.1):(0.65~0.85), and heating to manufacture the cobalt-free and nickel-free matrix material.

[0009] Here, the molar ratio of the lithium element in the lithium salt, the sodium element in the sodium salt, and the manganese element in the manganese salt is, for example, 0.2:0.9:0.65, 0.2:1:0.75, 0.25:1.1:0.85, 0.25:0.95:0.8, and 0.3:1.1:0.85, etc.

[0010] In one embodiment, the lithium salt comprises one or more combinations of lithium carbonate, lithium hydroxide, lithium chloride, or lithium fluoride.

[0011] In one embodiment, the manganese salt comprises one or more combinations of manganese acetate, manganese carbonate, manganese monoxide, dimanganate trioxide, or trimanganese tetroxide.

[0012] In one embodiment, the sodium salt comprises one or a combination of two or more of sodium carbonate, sodium acetate, sodium chloride, or sodium bicarbonate.

[0013] In one embodiment, in a method for manufacturing a cobalt-free and nickel-free matrix material, heating is performed in an oxygen-containing atmosphere, and the oxygen-containing atmosphere is an air atmosphere with a supply flow rate of 5 to 10 L / min, for example, the supply flow rate is 5.0 L / min, 5.5 L / min, 6.0 L / min, 6.5 L / min, 7.0 L / min, 7.5 L / min, 8.0 L / min, 8.5 L / min, 9.0 L / min, 9.5 L / min, or 10.0 L / min, etc., and in a method for manufacturing a cobalt-free and nickel-free matrix material, the heating temperature is 500 to 800°C, for example, the temperature is 500°C, 520°C, 540°C, 560°C, 580°C, 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, The temperature is 740℃, 760℃, 780℃, or 800℃, etc., and the heating time is 8 to 12 hours, for example, the time is 8.0h, 8.4h, 8.8h, 9.2h, 9.6h, 10.0h, 10.4h, 10.8h, 11.2h, 11.6h, or 12.0h, etc.

[0014] In one embodiment provided in the present invention, the cobalt-free and nickel-free matrix material, a divalent manganese compound, and a lithium source are mixed to obtain a mixture, and the molar ratio of the lithium element to the manganese element in the mixture is (0.8 to 1.5):1, for example, the molar ratio is 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1, etc.

[0015] In one embodiment, the amount of divalent manganese compound added is controlled to obtain a mixture by mixing a cobalt-free and nickel-free matrix material, a divalent manganese compound, and a lithium source, and then the molar ratio of lithium elements to manganese elements in the mixture is set to (0.8 to 1.5):1, thereby effectively suppressing the formation of layered LiMnO2 and improving the cycle performance of the battery. If the molar ratio of lithium elements to manganese elements is less than 0.8:1, too many lithium-deficient materials, such as spinel structures, are formed, resulting in a lower capacity; if the molar ratio of lithium elements to manganese elements exceeds 1.5:1, on the one hand, it causes a waste of cost, and on the other hand, the total alkali content of the material increases, affecting the performance of the material.

[0016] In one embodiment provided in the present invention, the divalent manganese compound comprises one or more combinations of MnO, Mn3O4, or MnCO3.

[0017] In one embodiment, the divalent manganese compound comprises a divalent manganese compound, for example, Mn3O4 containing both divalent manganese and trivalent manganese.

[0018] In one embodiment provided in the present invention, the mixing reaction is a melting reaction, and the temperature of the mixing reaction is 400 to 800°C, for example, the temperature is 400°C, 440°C, 480°C, 520°C, 560°C, 600°C, 640°C, 680°C, 720°C, 760°C, or 800°C, etc. The time of the mixing reaction is 4 to 8 hours, for example, the time is 4.0h, 4.4h, 4.8h, 5.2h, 5.6h, 6.0h, 6.4h, 6.8h, 7.2h, 7.6h, or 8.0h, etc.

[0019] In one embodiment, washing and drying are performed sequentially on the material after the mixing reaction.

[0020] In one embodiment, the washing step includes adding water to the reacted material and stirring and washing for 10 minutes, and the mass of the added water is twice the mass of the material.

[0021] In one embodiment, washing is performed to remove raw materials remaining in the reacted material. Since an excess amount of lithium salt is added during the manufacturing process, the residual alkali in the material increases, and the sodium salt formed during the calcination process is inactive, washing treatment is performed to remove the sodium salt and residual alkali in the material.

[0022] In one embodiment provided in the present invention, the cobalt-free and nickel-free cathode material obtained through the mixing reaction is also coated, and the coating method comprises the steps of: mixing the cobalt-free and nickel-free cathode material obtained by the reaction with AlPO4 and calcining it first to obtain an AlPO4-coated cathode material; and mixing the AlPO4-coated cathode material with TiO2 and calcining it second to obtain an AlPO4 and TiO2-coated cobalt-free and nickel-free cathode material.

[0023] In one embodiment, through a double-layer coating of AlPO4 and TiO2, TiO2 becomes the outer coating layer, and during the coating process, TiO2 is Li diffused from the active material +It combines with to form Li2TiO3, and as Li2TiO3 is a lithium-ion conductor, the Li2TiO3 formed on the surface can increase the ion diffusion rate, and additionally, AlPO4 becomes an internal coating layer, and during the cycling process, Al 3+ It diffuses into the oxide lattice and plays a role in stabilizing the structure, and PO4 3- 은 Li + It reacts with to produce Li3PO4, a conductor of lithium ions.

[0024] In one embodiment, the temperature of the first calcination is 300 to 800°C, for example, the temperature is 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or 800°C, the time of the first calcination is 5 to 8 hours, for example, the time is 5.0h, 5.3h, 5.6h, 5.9h, 6.2h, 6.5h, 6.8h, 7.1h, 7.4h, 7.7h, or 8.0h, and the atmosphere of the first calcination is air or oxygen.

[0025] In one embodiment, the temperature of the secondary calcination is 300 to 800°C, for example, the temperature is 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, or 800°C, the time of the secondary calcination is 5 to 8 hours, for example, the time is 5.0h, 5.3h, 5.6h, 5.9h, 6.2h, 6.5h, 6.8h, 7.1h, 7.4h, 7.7h, or 8.0h, and the atmosphere of the secondary calcination is air or oxygen.

[0026] In one embodiment provided in the present invention, based on the total mass of the cobalt-free and nickel-free cathode material, the coating amount of AlPO4 is 500 to 5000 ppm, for example, the coating amount is 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, or 5000 ppm, etc.

[0027] In one embodiment, the reason for controlling the coating amount of AlPO4 to 500 to 5,000 ppm is that if the coating amount is less than 500 ppm, there are problems such as uneven material coating and a thin coating layer thickness, poor separation effect from the electrolyte, and increased side reactions, which degrades the electrical characteristics of the battery. If the coating amount exceeds 5,000 ppm, the thickness of the material coating layer becomes too thick, and Li + This is because it interferes with the insertion and removal of the material, affecting its capacity and rate characteristics.

[0028] In one embodiment, based on the total mass of the cobalt-free and nickel-free cathode material, the coating amount of TiO2 is 500 to 5000 ppm, for example, the coating amount is 500 ppm, 1000 ppm, 1500 ppm, 2000 ppm, 2500 ppm, 3000 ppm, 3500 ppm, 4000 ppm, 4500 ppm, or 5000 ppm, etc.

[0029] In one embodiment, the reason for controlling the TiO2 coating amount to 500 to 5,000 ppm is that if the coating amount is less than 500 ppm, there are problems such as non-uniform material coating and a thin coating layer thickness, poor separation effect with the electrolyte, and increased side reactions, which degrades the electrical characteristics of the battery. If the coating amount exceeds 5,000 ppm, the thickness of the material coating layer becomes too thick, and Li + This is because it interferes with the insertion and removal of the material, affecting its capacity and rate characteristics.

[0030] In one embodiment, the manufacturing method specifically includes the following steps.

[0031] (I) A lithium salt, a sodium salt, and a manganese salt are mixed, wherein the molar ratio of the lithium element, the sodium element, and the manganese element is (0.2~0.3):(0.9~1.1):(0.65~0.85), and the mixture is heated at 500~800°C for 8~12 hours in an air atmosphere to produce the above cobalt-free and nickel-free matrix material, and the air flow rate is 5~10 L / min.

[0032] (II) A mixture is obtained by mixing the cobalt-free and nickel-free matrix material prepared in step (I), a lithium source, and a divalent manganese compound, wherein the molar ratio of lithium elements to manganese elements in the mixture is (0.8~1.5):1, and a melting reaction is carried out at 400~800°C for 4~8 hours, and washing and drying are performed after the reaction.

[0033] (III) The dried cobalt-free and nickel-free cathode material is mixed with AlPO4 and calcined first at 300 to 800°C in an air or oxygen atmosphere for 5 to 8 hours to coat AlPO4, with a coating amount of 500 to 5000 ppm of AlPO4; the material is mixed with TiO2 and calcined second at 300 to 800°C in an air or oxygen atmosphere for 5 to 8 hours to coat TiO2, with a coating amount of 500 to 5000 ppm of TiO2, thereby producing the cobalt-free and nickel-free cathode material.

[0034] In one embodiment provided by the present invention, a cobalt-free and nickel-free cathode material is provided, and said cobalt-free and nickel-free cathode material comprises layered LiMnO3, spinel Li2MnO4, and layered Li2MnO3.

[0035] In one embodiment, a typical but non-limiting chemical formula of the cobalt-free and nickel-free cathode material is Li a Mn bO2, 0.8≤a≤1, 0.7≤b≤0.8, for example, a is 0.80, 0.82, 0.84, 0.86, 0.88, 0.90, 0.92, 0.94, 0.96, 0.98 or 1.00, etc., and b is 0.70, 0.71, 0.72, 0.73, 0.74, 0.75, 0.76, 0.77, 0.78, 0.79 or 0.80, etc.

[0036] In one embodiment provided in the present invention, the molar ratio of the layered Li2MnO3 in the cobalt-free and nickel-free cathode material is 50 to 90%, for example 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90%, etc.

[0037] In one embodiment provided in the present invention, the molar ratio of the layered Li2MnO3 in the cobalt-free and nickel-free cathode material is 70%.

[0038] In one embodiment provided by the present invention, a battery is provided, said battery comprises a positive electrode, a negative electrode, and a separator, said positive electrode uses a cobalt-free and nickel-free positive electrode material according to one embodiment. Brief explanation of the drawing

[0039] The attached drawings provide a further understanding of the means for solving the problem of the present invention, constitute part of the specification, and are used to explain the technical solution of the present invention together with embodiments of the present invention. This does not constitute a limitation on the means for solving the problem of the present invention. Figure 1 is a scanning electron microscope image at 2000x magnification of a cobalt-free and nickel-free cathode material manufactured in one embodiment of the present invention. Figure 2 is a scanning electron microscope image at 3000x magnification of a cobalt-free and nickel-free cathode material manufactured in one embodiment of the present invention. Figure 3 is an XRD pattern of a cobalt-free and nickel-free cathode material manufactured in one embodiment of the present invention. Figure 4 is a graph of the 1st and 2nd charge-discharge cycles of the cobalt-free and nickel-free cathode material prepared in Comparative Example 1 of the present invention. Figure 5 is a graph showing the 1st, 2nd, and 20th charge-discharge cycles of a cobalt-free and nickel-free cathode material manufactured in one embodiment of the present invention. Specific details for implementing the invention

[0040] Hereinafter, the means for solving the problem of the present invention will be explained in more detail through specific embodiments with reference to the attached drawings.

[0041] Example 1

[0042] A method for manufacturing cobalt-free and nickel-free cathode materials includes the following steps.

[0043] (I) Lithium carbonate, sodium carbonate, and manganese carbonate are mixed such that the molar ratio of the lithium, sodium, and manganese elements is 0.25:1:0.75, and the mixture is heated at 750°C for 10 hours in an air atmosphere to prepare the cobalt-free and nickel-free matrix material, the general formula being NaLi 0.25 Mn 0.75 It is O2, and the air flow rate is 7.5 L / min.

[0044] (II) A mixture is obtained by mixing the cobalt-free and nickel-free matrix material prepared in step (I), lithium carbonate, and MnO, wherein the molar ratio of lithium elements to manganese elements in the mixture is 1.2:1, and a melting reaction is performed at 600°C for 6 hours, and water is added to the reacted material and stirred and washed for 10 minutes, wherein the mass of water added is twice the mass of the material, and drying is performed after washing.

[0045] (III) The dried cobalt-free and nickel-free cathode material is mixed with AlPO4 and calcined first at 550°C in an air atmosphere for 6.5 hours to coat AlPO4, with a coating amount of 500 ppm of AlPO4; the mixture is mixed with TiO2 and calcined second at 550°C in an oxygen atmosphere for 6.5 hours to coat TiO2, with a coating amount of 500 ppm of TiO2, thereby producing the cobalt-free and nickel-free cathode material.

[0046] The chemical formula of the cobalt-free and nickel-free cathode material prepared in this example is Li 0.92 Mn 0.76 It is O2, and the molar ratio of layered Li2MnO3 is 70%.

[0047] Referring to FIGS. 1 and 2, it can be seen that the cobalt-free and nickel-free cathode materials manufactured in this embodiment have an irregular single-crystal structure, and FIG. 3 is an XRD characteristic analysis diagram, showing that the material contains layered Li2MnO3.

[0048] Example 2

[0049] A method for manufacturing cobalt-free and nickel-free cathode materials includes the following steps.

[0050] (I) lithium hydroxide, sodium acetate, and manganese monoxide are mixed such that the molar ratio of lithium, sodium, and manganese elements is 0.25:1:0.75, and the mixture is heated at 500°C for 12 hours in an air atmosphere to prepare the cobalt-free and nickel-free matrix material, the general formula being NaLi 0.25 Mn 0.75 It is O2, and the air flow rate is 5L / min.

[0051] (II) A mixture is obtained by mixing the cobalt-free and nickel-free matrix material prepared in step (I), lithium hydroxide, and Mn3O4, wherein the molar ratio of lithium elements to manganese elements in the mixture is 0.9:1, and a melting reaction is performed at 400°C for 8 hours, and water is added to the reacted material and stirred and washed for 10 minutes, wherein the mass of water added is twice the mass of the material, and drying is performed after washing.

[0052] (III) The dried cobalt-free and nickel-free cathode material is mixed with AlPO4 and calcined first at 800°C in an air atmosphere for 5 hours to coat AlPO4, with a coating amount of 1000 ppm of AlPO4; the mixture is mixed with TiO2 and calcined second at 700°C in an air atmosphere for 5.5 hours to coat TiO2, with a coating amount of 1000 ppm of TiO2, thereby producing the cobalt-free and nickel-free cathode material.

[0053] The chemical formula of the cobalt-free and nickel-free cathode material prepared in this example is Li 0.8 Mn 0.89 It is O2, and the molar ratio of layered Li2MnO3 is 50%.

[0054] Example 3

[0055] A method for manufacturing cobalt-free and nickel-free cathode materials includes the following steps.

[0056] (I) Lithium chloride, sodium chloride, and dimanganese trioxide are mixed such that the molar ratio of lithium, sodium, and manganese elements is 0.25:1:0.75, and the mixture is heated at 800°C for 8 hours in an air atmosphere to prepare the cobalt-free and nickel-free matrix material, the general formula being NaLi 0.25 Mn 0.75 It is O2, and the air flow rate is 10L / min.

[0057] (II) A mixture is obtained by mixing the cobalt-free and nickel-free matrix material prepared in step (I), lithium chloride, and MnCO3, wherein the molar ratio of lithium elements to manganese elements in the mixture is 1.5:1, and a melting reaction is performed at 800°C for 4 hours, and water is added to the reacted material and stirred and washed for 10 minutes, wherein the mass of water added is twice the mass of the material, and drying is performed after washing.

[0058] (III) The dried cobalt-free and nickel-free cathode material is mixed with AlPO4 and calcined first at 300°C in an oxygen atmosphere for 8 hours to coat AlPO4, with a coating amount of 3000 ppm of AlPO4; the material is mixed with TiO2 and calcined second at 300°C in an oxygen atmosphere for 8 hours to coat TiO2, with a coating amount of 3000 ppm of TiO2, thereby producing the cobalt-free and nickel-free cathode material.

[0059] The chemical formula of the cobalt-free and nickel-free cathode material prepared in this example is Li 1.05 Mn 0.7 It is O2, and the molar ratio of layered Li2MnO3 is 87.5%.

[0060] Example 4

[0061] A method for manufacturing cobalt-free and nickel-free cathode materials includes the following steps.

[0062] (I) Lithium fluoride, sodium bicarbonate, and manganese acetate are mixed such that the molar ratio of lithium, sodium, and manganese elements is 0.25:1:0.75, and the mixture is heated at 650°C for 9 hours in an air atmosphere to prepare the cobalt-free and nickel-free matrix material, the general formula being NaLi 0.25 Mn 0.75 It is O2, and the air flow rate is 7L / min.

[0063] (II) A mixture is obtained by mixing the cobalt-free and nickel-free matrix material prepared in step (I), lithium fluoride, and MnO, wherein the molar ratio of lithium elements to manganese elements in the mixture is 1:1, and a melting reaction is performed at 700°C for 5 hours, and water is added to the reacted material and stirred and washed for 10 minutes, wherein the mass of water added is twice the mass of the material, and drying is performed after washing.

[0064] (III) The dried cobalt-free and nickel-free cathode material is mixed with AlPO4 and calcined first at 700°C in an air atmosphere for 7 hours to coat AlPO4, with a coating amount of 5000 ppm of AlPO4; the material is mixed with TiO2 and calcined first at 800°C in an oxygen atmosphere for 5 hours to coat TiO2, with a coating amount of 5000 ppm of TiO2, thereby producing the cobalt-free and nickel-free cathode material.

[0065] The chemical formula of the cobalt-free and nickel-free cathode material prepared in this example is Li 0.8 Mn 0.8 It is O2, and the molar ratio of layered Li2MnO3 is 55%.

[0066] Example 5

[0067] A method for manufacturing cobalt-free and nickel-free cathode materials includes the following steps.

[0068] (I) Lithium fluoride, sodium bicarbonate, and manganese acetate are mixed such that the molar ratio of lithium, sodium, and manganese elements is 0.25:1:0.75, and the mixture is heated at 600°C for 9 hours in an air atmosphere to prepare the cobalt-free and nickel-free matrix material, the general formula being NaLi 0.25 Mn 0.75 It is O2, and the air flow rate is 9L / min.

[0069] (II) A mixture is obtained by mixing the cobalt-free and nickel-free matrix material prepared in step (I), lithium carbonate, and MnO, wherein the molar ratio of lithium elements to manganese elements in the mixture is 1.3:1, and a melting reaction is performed at 500°C for 7 hours, and water is added to the reacted material and stirred and washed for 10 minutes, wherein the mass of water added is twice the mass of the material, and drying is performed after washing.

[0070] (III) The dried cobalt-free and nickel-free cathode material is mixed with AlPO4 and calcined first at 400°C in an oxygen atmosphere for 7.5 hours to coat AlPO4, with a coating amount of 1500 ppm of AlPO4; the mixture is mixed with TiO2 and calcined second at 400°C in an oxygen atmosphere for 7.5 hours to coat TiO2, with a coating amount of 2000 ppm of TiO2, thereby producing the cobalt-free and nickel-free cathode material.

[0071] The chemical formula of the cobalt-free and nickel-free cathode material prepared in this example is Li 0.98 Mn 0.75 It is O2, and the molar ratio of layered Li2MnO3 is 78%.

[0072] Example 6

[0073] The difference from Example 1 is that the molar ratio of lithium to manganese elements in step (II) was changed to 0.6:1. The chemical formula of the manufactured cobalt-free and nickel-free cathode material is Li 0.5 Mn 0.83 It is O2 and does not contain layered Li2MnO3.

[0074] Example 7

[0075] The difference from Example 1 is that the molar ratio of lithium to manganese elements in step (II) was changed to 1.7:1. The chemical formula of the manufactured cobalt-free and nickel-free cathode materials is Li 1.2 Mn 0.7It is O2, and the molar ratio of layered Li2MnO3 is 94%.

[0076] Example 8

[0077] The difference from Example 1 is that step (III) was not performed, that is, AlPO4 coating and TiO2 coating were not performed.

[0078] Example 9

[0079] The difference from Example 1 is that AlPO4 coating was not performed in step (III).

[0080] Example 10

[0081] The difference from Example 1 is that TiO2 coating was not performed in step (III).

[0082] Example 11

[0083] The difference from Example 1 is that in step (III), the coating amount of AlPO4 was changed to 300 ppm and the coating amount of TiO2 was changed to 300 ppm.

[0084] Example 12

[0085] The difference from Example 1 is that in step (III), the coating amount of AlPO4 was changed to 6000 ppm and the coating amount of TiO2 was changed to 6000 ppm.

[0086] Comparative Example 1

[0087] The difference from Example 1 is that MnO was not added in step (II). The molar ratio of layered Li2MnO3 in the prepared cobalt-free and nickel-free cathode material is 20%.

[0088] Comparison Example 2

[0089] The difference from Example 1 is that MnO was replaced with MnO2 in step (II). The molar ratio of layered Li2MnO3 in the manufactured cobalt-free and nickel-free cathode material is 25%.

[0090] A method for assembling a battery using the cobalt-free and nickel-free cathode materials prepared in the examples and control examples provided in the present invention: A suitable amount of material was taken and homogenized and coated, and the ratio of cobalt-free and nickel-free cathode material : Sp : PVDF adhesive = 92:4:4, and the solid content of the PVDF adhesive is 6.05%. The prepared sheet was assembled into a button battery using a CR2032 case. Here, Sp represents conductive carbon black, PVDF represents polyvinylidene fluoride, and the CR2032 case represents a cylindrical shell with a diameter of 20 mm and a height of 3.2 mm.

[0091] The obtained button battery was subjected to a cycle performance test under conditions of 2 to 4.6 V, and the test results are shown in Table 1. Figure 4 is a graph of the 1st and 2nd charge-discharge cycles of a battery assembled with the cobalt-free and nickel-free cathode material of Comparative Example 1, and Figure 5 is a graph of the 1st, 2nd, and 51st charge-discharge cycles of a battery assembled with the cobalt-free and nickel-free cathode material of Example 1.

[0092] number AlPO4 coating amount (ppm) TiO2 coating amount (ppm) 0.1C charging capacity (mAh / g) 0.1C discharge (mAh / g) Initial efficiency (%) 0.1C discharge capacity (mAh / g) 20-dose retention rate (%) 50-dose retention rate (%) Example 1 500 500 250.1 244.1 97.6 205.8 88.5 85.6 Example 2 1000 1000 258.4 254.4 98.5 204.8 90.2 84.2 Example 3 3000 3000 259.9 255.7 98.4 206.1 98.7 90.2 Example 4 5000 5000 253.4 246.2 97.2 203.4 91.5 85.6 Example 5 1500 2000 259.5 251.6 97.0 204.1 94.2 85.9 Example 6 500 500 240.2 231.1 96.2 188.2 75.4 50.6 Example 7 500 500 234.5 195.8 83.5 165.7 75.3 52.5 Example 8 0 0 259.0 254.4 98.2 205.6 75.2 40.2 Example 9 0 500 254.4 251.1 98.7 201.1 78.4 68.9 Example 10 500 0 255.1 252.1 98.8 204.1 68.7 61.2 Example 11 300 300 240.3 221.2 92.0 189.2 85.6 65.4 Example 12 6000 6000 246.6 231.5 93.9 193.6 90.4 84.6 Comparative Example 1 500 500 264.9 231.5 87.4 101.4 60.2 45.2 Comparison Example 2 500 500 263.8 231.8 88.0 104.4 61.3 46.6

[0093] Comparing Example 1 with Examples 6 and 7, it can be seen that by controlling the amount of divalent manganese compound added, when a cobalt-free and nickel-free matrix material, a divalent manganese compound, and a lithium source are mixed, if the molar ratio of lithium to manganese elements is (0.8~1.5):1, the formation of layered LiMnO2 is effectively suppressed, thereby improving the cycle performance of the battery; if the molar ratio of lithium to manganese elements is less than 0.8:1, too many lithium-deficient materials, such as spinel structures, are formed, resulting in a lower capacity; and if the molar ratio of lithium to manganese elements exceeds 1.5:1, on the one hand, it causes cost waste, and on the other hand, the total alkali content of the material increases, affecting material performance.

[0100] Comparing Example 1 with Examples 8, 9, and 10, through double-layer coating, TiO2 becomes the outer coating layer, and during the coating process, TiO2 [contains] Li diffused from the active material + It combines with to form Li2TiO3, and as Li2TiO3 is a lithium-ion conductor, the Li2TiO3 formed on the surface can increase the ion diffusion rate, and additionally, AlPO4 becomes an internal coating layer, and during the cycling process, Al 3+ It diffuses into the oxide lattice and plays a role in stabilizing the structure, and PO4 3- 은 Li + It can be seen that it reacts with to produce Li3PO4, a conductor of lithium ions.

[0094] Comparing Example 1 with Examples 11 and 12, the reason for controlling the AlPO4 coating amount to 500–5000 ppm is that if the coating amount is less than 500 ppm, the material coating becomes uneven and the coating layer thickness is thin; furthermore, the separation effect from the electrolyte is poor and side reactions increase, degrading the electrical characteristics of the battery. If the coating amount exceeds 5000 ppm, the thickness of the material's coating layer becomes too thick, and Li + This is because it interferes with the insertion and removal of the material, affecting its capacity and rate characteristics.

[0095] Comparing Example 1 with Control Examples 1 and 2 and referring to FIGS. 4 and 5, it can be seen that there are two capacitance platforms at 3.5 to 4.5 V, which indicates the presence of a LiMnO2 phase in the material; capacitance loss occurs during the cycling process due to layered LiMnO3 and spinel Li2MnO4, and Mn 3+ Due to the disproportionation reaction and the Jahn-Teller effect of Li2MnO4 during the cycling process, the material cycling performance of Comparative Example 1 is poor, and the retention rate after 20 cycles is only 60.2%. By adding a divalent manganese compound during the manufacturing process, the formation of layered LiMnO2 and spinel Li2MnO4 is effectively suppressed, and the formation of Li2MnO3 is promoted, thereby effectively improving the cycling performance of cobalt-free and nickel-free materials.

Claims

Claim 1 A method for manufacturing a cobalt-free and nickel-free cathode material, wherein the manufacturing method comprises the step of manufacturing a cobalt-free and nickel-free matrix material; wherein the general formula of the cobalt-free and nickel-free matrix material is Na x Li y Mn 0.75 The method comprises the step of preparing a cobalt-free and nickel-free cathode material by mixing and reacting the cobalt-free and nickel-free matrix material, a lithium source, and a divalent manganese compound, wherein the cobalt-free and nickel-free matrix material, the divalent manganese compound, and the lithium source are mixed to obtain a mixture, and the molar ratio of lithium elements to manganese elements in the mixture is (0.8~1.5):1, and the cobalt-free and nickel-free cathode material obtained through the mixing reaction is also coated, and the coating method comprises the step of mixing the cobalt-free and nickel-free cathode material obtained by the reaction with AlPO4 and performing a first calcination to obtain an AlPO4-coated cathode material; A method for manufacturing a cobalt-free and nickel-free cathode material comprising the step of mixing the AlPO4-coated cathode material with TiO2 and calcining it a second time to obtain an AlPO4 and TiO2-coated cobalt-free and nickel-free cathode material, wherein, based on the total mass of the cobalt-free and nickel-free cathode material, the coating amount of AlPO4 is 500 to 5000 ppm and the coating amount of TiO2 is 500 to 5000 ppm. Claim 2 In paragraph 1, the above Na x Li y Mn 0.75 A method for manufacturing cobalt-free and nickel-free cathode materials in which 0.8≤x≤1 and 0≤y≤0.35 are given by the general formula O2. Claim 3 A method for manufacturing a cobalt-free and nickel-free matrix material according to claim 1 or 2, comprising the step of mixing a lithium salt, a manganese salt, and a sodium salt, wherein the molar ratio of the lithium element in the lithium salt, the sodium element in the sodium salt, and the manganese element in the manganese salt is (0.2~0.3):(0.9~1.1):(0.65~0.85), and heating to manufacture the cobalt-free and nickel-free matrix material. Claim 4 A method for manufacturing a cobalt-free and nickel-free cathode material according to claim 3, wherein the heating temperature in the method for manufacturing the cobalt-free and nickel-free matrix material is 500 to 800°C and the heating time is 8 to 12 hours. Claim 5 delete Claim 6 A method for manufacturing a cobalt-free and nickel-free cathode material according to claim 1, wherein the divalent manganese compound comprises one or more combinations of MnO, Mn3O4, or MnCO3. Claim 7 A method for manufacturing a cobalt-free and nickel-free cathode material according to claim 1, wherein the mixing reaction is a melting reaction, the temperature of the mixing reaction is 400 to 800°C, and the time of the mixing reaction is 4 to 8 hours. Claim 8 delete Claim 9 A method for manufacturing a cobalt-free and nickel-free cathode material according to claim 1, wherein the temperature of the first calcination is 300 to 800°C, the time of the first calcination is 5 to 8 hours, and the atmosphere of the first calcination is air or oxygen. Claim 10 A method for manufacturing a cobalt-free and nickel-free cathode material according to claim 1, wherein the temperature of the secondary calcination is 300 to 800°C, the time of the secondary calcination is 5 to 8 hours, and the atmosphere of the secondary calcination is air or oxygen. Claim 11 delete Claim 12 A cobalt-free and nickel-free cathode material manufactured by the manufacturing method according to claim 1, wherein the cobalt-free and nickel-free cathode material comprises layered LiMnO3, spinel Li2MnO4, and layered Li2MnO3. Claim 13 In claim 12, a cobalt-free and nickel-free cathode material in which the molar ratio of the layered Li2MnO3 in the cobalt-free and nickel-free cathode material is 50 to 90%. Claim 14 A battery comprising a positive electrode, a negative electrode, and a separator, wherein the positive electrode uses the cobalt-free and nickel-free positive electrode material of claim 12 or 13.

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