A nickel-cobalt-manganese ternary positive electrode material with multi-element doping to improve safety performance and voltage platform and its preparation method

Abstract

The present invention provides a nickel-cobalt-manganese ternary positive electrode material with improved safety performance and voltage platform by multi-element doping and a preparation method thereof, the general chemical formula of which is LiNi a Co b Mn c Fe d Na e Al f Si g Ca h O2, wherein a+b+c+d+e+f+g+h=1, 0.40≤a+b+c≤0.95, 0.05≤d+e≤0.5, 0.02≤f+g+h≤0.2. The present invention introduces Fe, Na and a small amount of Al, Si and Ca during the sintering of the positive electrode material, adopts a high-temperature solid-phase reaction, and controls the reaction parameters such as the L / M ratio, temperature, and the doping amount of the elements to prepare a multi-element doped nickel-cobalt-manganese ternary positive electrode material. This overcomes the shortcomings of previous ternary positive electrode materials, such as poor safety performance and low voltage platform. In addition, all doping elements are derived from the mixed red mud, which is easy to obtain, energy-saving and environmentally friendly, and has a simple process and is easy to achieve industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium-ion battery materials, and in particular to a nickel-cobalt-manganese ternary positive electrode material with multi-element doping to improve safety performance and voltage platform, and a preparation method thereof. Background Art

[0002] In recent years, with the continuous development of lithium-ion batteries, ternary positive electrode materials have become the preferred choice of many lithium battery manufacturers due to their high power and high energy density, prompting people to continuously improve ternary positive electrode materials. High-nickel ternary lithium-ion batteries have high energy density due to their high nickel content, and their low cobalt content makes the cost more advantageous, making high-nickel ternary positive electrode materials one of the inevitable directions for the future development of lithium batteries.

[0003] However, there are serious problems at present: the mixed Li / Ni arrangement leads to poor battery cycle; the increase in Ni4+ content causes the internal O2- to be oxidized to generate oxygen, which reacts with the electrolyte, resulting in thermal runaway, and the release of oxygen will also form holes in the battery, greatly reducing the battery safety performance; due to the continuous decrease in cobalt content, the voltage platform of battery discharge is also continuously decreasing, reducing the electrochemical performance of the battery.

[0004] Therefore, it is necessary to provide a nickel-cobalt-manganese ternary positive electrode material with improved safety performance and voltage platform through multi-element doping and a preparation method thereof to solve the above-mentioned existing problems. Summary of the Invention

[0005] In view of this, the present invention provides a nickel-cobalt-manganese ternary positive electrode material with multi-element doping to improve safety performance and voltage platform and a preparation method thereof. The nickel-cobalt-manganese ternary positive electrode material prepared by the present invention overcomes the shortcomings of previous ternary positive electrode materials such as poor safety performance and low voltage platform.

[0006] To achieve the above technical effects, the present invention provides a nickel-cobalt-manganese ternary cathode material with improved safety performance and voltage platform through multi-element doping and a preparation method thereof, which adopts the following technical solutions:

[0007] A nickel-cobalt-manganese ternary positive electrode material with multi-element doping to improve safety performance and voltage platform, wherein the chemical formula of the nickel-cobalt-manganese ternary positive electrode material is LiNi a Co b Mn c Fe d Na e Al f Si g Ca h O2, where a+b+c+d+e+f+g+h=1, 0.40≤a+b+c≤0.95, 0.05≤d+e≤0.5, 0.02≤f+g+h≤0.2.

[0008] A method for preparing a nickel-cobalt-manganese ternary cathode material with multi-element doping to improve safety performance and voltage platform, comprising the following steps:

[0009] Step 1, weighing the lithium source, nickel-cobalt-manganese hydroxide and red mud respectively according to proportion;

[0010] Step 2: uniformly mixing the lithium source, nickel-cobalt-manganese hydroxide and red mud weighed in step 1 and calcining the mixture to obtain a lithium nickel-cobalt-manganese oxide bulk material;

[0011] Step 3, crushing the lithium nickel cobalt manganese oxide block material obtained in step 2 on a double-roll crusher to obtain a lithium nickel cobalt manganese oxide double-roll material;

[0012] Step 4: The lithium nickel cobalt manganese oxide double roller material obtained in step 3 is crushed on a jet mill, and after screening, a nickel cobalt manganese ternary positive electrode material with multi-element doping to improve safety performance and voltage platform is obtained.

[0013] Furthermore, the lithium source is one of lithium carbonate and lithium hydroxide, and the nickel-cobalt-manganese hydroxide is Ni 0.5 Co 0.2 Mn 0.3 (OH)2、Ni 0.6 Co 0.1 Mn 0.3 (OH)2、Ni 0.7 Co 0.1 Mn 0.2 (OH)2、Ni 0.8 Co 0.1 Mn 0.1 (OH)2、Ni 0.88 Co 0.8 Mn 0.4 At least one of (OH)2.

[0014] Furthermore, the molar ratio of the lithium element in the lithium source to the cobalt element introduced into the nickel-cobalt-manganese hydroxide is (0.9-1.3):1, and the mass ratio of the red mud to the nickel-cobalt-manganese hydroxide is (0.001-0.2):1.

[0015] Furthermore, in step 2, the atmosphere used for calcination is air or oxygen, the heating time is 2h-15h, the constant temperature time is 2h-20h, and the constant temperature is 600-1100°C.

[0016] Furthermore, in step 3, the gap between the rollers is ≤4 μm.

[0017] Furthermore, in step 4, the crushing air pressure is 0.02-0.7 MPa.

[0018] The above technical solution of the present invention includes at least the following beneficial effects:

[0019] 1. The present invention introduces Fe, Na and a small amount of Al, Si and Ca during the sintering of the positive electrode material, adopts a high-temperature solid-phase reaction, and prepares a multi-element doped nickel-cobalt-manganese ternary positive electrode material by controlling the reaction parameters such as the L / M ratio, temperature, sintering time, and the doping amount of the elements;

[0020] 2. The multi-element doped nickel-cobalt-manganese ternary cathode material prepared by the method of the present invention overcomes the shortcomings of previous ternary cathode materials, such as poor safety performance and low voltage platform;

[0021] 3. The multi-element doped nickel-cobalt-manganese ternary cathode material prepared by the method of the present invention can meet the following performance requirements: thickness expansion <5% after storage at 80°C for 4 hours; discharge capacity retention ≥90% after storage at 55°C for 2 hours; and voltage platform improved by more than 10% compared with existing comparative cases;

[0022] 4. The characteristics of the present invention are that all doping elements are derived from mixed red mud, which is easy to obtain, energy-saving and environmentally friendly, and has a simple process and is easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a morphology image of the nickel-cobalt-manganese ternary positive electrode material prepared in Example 1 of the present invention under a 5000x electron microscope.

[0024] Figure 2 This is a morphology image of the nickel-cobalt-manganese ternary positive electrode material prepared in Example 2 of the present invention under a 5000x electron microscope.

[0025] Figure 3 This is a morphology image of the nickel-cobalt-manganese ternary positive electrode material prepared in Comparative Example 1 of the present invention under a 5000x electron microscope.

[0026] Figure 4 This is a morphology image of the nickel-cobalt-manganese ternary positive electrode material prepared in Comparative Example 2 of the present invention under a 5000x electron microscope. DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will be combined with the appended drawings of the embodiments of the present invention. Figure 1-4 , clearly and completely describing the technical solutions of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments derived by ordinary technicians in this field fall within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing a nickel-cobalt-manganese ternary positive electrode material with improved safety performance and voltage platform by multi-element doping comprises the following steps:

[0030] Step 1: Weigh 200g of Ni 0.7 Co 0.1 Mn 0.2 (OH)2, 92 g lithium carbonate, and 10 g red mud were added into a food processor and mixed evenly to obtain a mixture;

[0031] Step 2: Add the mixture obtained in step 1 into a crucible, and calcine in a roller kiln under an oxygen atmosphere with a heating time of 12 hours, a constant temperature time of 15 hours, and a constant temperature of 880° C. to obtain a block material after taking it out of the furnace;

[0032] Step 3: Add the block material obtained in step 2 to a roller crusher with a roller gap of 2 mm for crushing to obtain a coarsely crushed material;

[0033] Step 4: Add the coarsely crushed material obtained in step 3 to a jet mill with a crushing pressure of 0.2 MPa and grind it into lithium nickel cobalt manganese oxide primary crushed material after sieving;

[0034] Figure 1 This is a scanning electron microscope image of the multi-element doped nickel-cobalt-manganese ternary positive electrode material prepared in Example 1.

[0035] Example 2

[0036] A multi-element doped nickel-cobalt-manganese ternary positive electrode material is prepared, and the preparation method includes the following steps:

[0037] 1) Weigh 200g Ni 0.7 Co 0.1 Mn 0.2 (OH)2, 92 g of lithium carbonate, and 20 g of red mud were added into a food processor and mixed evenly to obtain a mixture;

[0038] 2) adding the mixture obtained in step 1) into a crucible, and calcining in a roller kiln under an oxygen atmosphere with a heating time of 12 hours and a constant temperature time of 15 hours at a constant temperature of 900° C. to obtain a block material after being taken out of the furnace;

[0039] 3) adding the bulk material obtained in step 2) to a roller crusher with a roller gap of 2 mm for crushing to obtain a coarsely crushed material;

[0040] 4) adding the coarsely crushed material obtained in step 3) into a jet mill at a crushing pressure of 0.2 MPa and crushing it, and sieving it to obtain a primary crushed material of lithium nickel cobalt manganese oxide;

[0041] Figure 2 This is a scanning electron microscope image of the multi-element doped nickel-cobalt-manganese ternary positive electrode material prepared in Example 2.

[0042] Comparative Example 1

[0043] The difference between Comparative Example 1 and Example 1 is that the positive electrode material is not doped.

[0044] 1) Weigh 200g Ni 0.7 Co 0.1 Mn 0.2 (OH)2 and 92 g of lithium carbonate were added into a food processor and mixed evenly to obtain a mixture;

[0045] 2) adding the mixture obtained in step 1) into a crucible, and calcining in a roller kiln under an oxygen atmosphere with a heating time of 12 hours and a constant temperature time of 15 hours at a constant temperature of 880° C. to obtain a block material after being taken out of the furnace;

[0046] 3) adding the bulk material obtained in step 2) to a roller crusher with a roller gap of 2 mm for crushing to obtain a coarsely crushed material;

[0047] 4) adding the coarsely crushed material obtained in step 3) into a jet mill at a crushing pressure of 0.2 MPa and crushing it, and sieving it to obtain a primary crushed material of lithium nickel cobalt manganese oxide;

[0048] Figure 3 This is a scanning electron microscope image of the multi-element doped nickel-cobalt-manganese ternary positive electrode material prepared in Comparative Example 1.

[0049] Comparative Example 2

[0050] The difference between Comparative Example 2 and Example 2 is that the positive electrode material is not doped.

[0051] 1) Weigh 200g Ni 0.7 Co 0.1 Mn 0.2 (OH)2 and 92 g of lithium carbonate were added into a food processor and mixed evenly to obtain a mixture;

[0052] 2) adding the mixture obtained in step 1) into a crucible, and calcining in a roller kiln under an oxygen atmosphere with a heating time of 12 hours and a constant temperature time of 15 hours at a constant temperature of 900° C. to obtain a block material after being taken out of the furnace;

[0053] 3) adding the bulk material obtained in step 2) to a roller crusher with a roller gap of 2 mm for crushing to obtain a coarsely crushed material;

[0054] 4) adding the coarsely crushed material obtained in step 3) into a jet mill at a crushing pressure of 0.2 MPa and crushing it, and sieving it to obtain a primary crushed material of lithium nickel cobalt manganese oxide;

[0055] Figure 4 This is a scanning electron microscope image of the multi-element doped nickel-cobalt-manganese ternary positive electrode material prepared in Comparative Example 2.

[0056] Example 1, Comparative Example 1, Example 2, and Comparative Example 2 of the present invention were used to prepare positive electrode materials and assembled into button half-cells, specifically as follows: the obtained ternary positive electrode material, carbon black, and polyvinylidene fluoride were mixed in a mass ratio of 95:2.5:2.5, NMP was added, and the mixture was stirred to form a slurry, which was then coated on aluminum foil. After drying, it was made into a positive electrode. Carbon was used as the negative electrode, and the button half-cells were assembled in a glove box.

[0057] The chemical formulas of the positive electrode materials obtained in Example 1, Comparative Example 1, Comparative Example 2 and Example 2 are respectively:

[0058] Example 1: LiNi 0.672 Co 0.096 Mnc 0.192 Fe 0.025 Na 0.006 Al 0.004 Si 0.003 Ca 0.002 O2

[0059] Comparative Example 1: LiNi 0.7 Co 0.1 Mnc 0.2 O2

[0060] Example 2: LiNi 0.644 Co 0.092 Mnc 0.184 Fe 0.050 Na 0.012 Al 0.008 Si 0.006 Ca 0.004 O2

[0061] Comparative Example 2: LiNi 0.7 Co 0.1 Mnc 0.2 O2

[0062] The button batteries obtained in Example 1, Comparative Example 1, Comparative Example 2 and Example 2 were subjected to storage at 80° C. for 4 hours, storage at 55° C. for 2 hours and charge and discharge voltage platform testing. The results are shown in Table 1.

[0063] Table 1. Electrochemical performance parameters of button cells of Examples 1-2 and Comparative Examples 1-2

[0064]

[0065] As shown in Table 1, the expansion rate of the sample doped with red mud at 80℃*4H is significantly smaller than that of the undoped sample, the capacity retention rate at 55℃*2H is also greatly improved, and the average discharge voltage (3.0~4.5V) is also significantly improved.

[0066] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a nickel-cobalt-manganese ternary cathode material with improved safety performance and voltage platform by multi-element doping, characterized in that: The general chemical formula of the nickel-cobalt-manganese ternary positive electrode material is LiNi a Co b Mn c Fe d Na e Al f Si g Ca h O2, wherein a+b+c+d+e+f+g+h=1, 0.40≤a+b+c≤0.95, 0.05≤d+e≤0.5, 0.02≤f+g+h≤0.2, is used to prepare a nickel-cobalt-manganese ternary positive electrode material with multi-element doping to improve safety performance and voltage platform, comprising the following steps: Step 1, weighing a lithium source, nickel-cobalt-manganese hydroxide and red mud respectively in proportion, wherein the molar ratio of the lithium element in the lithium source to the cobalt element introduced into the nickel-cobalt-manganese hydroxide is (0.9-1.3):1, and the mass ratio of the red mud to the nickel-cobalt-manganese hydroxide is (0.001-0.2):1; Step 2: uniformly mix the lithium source, nickel-cobalt-manganese hydroxide and red mud weighed in step 1 and calcine them in an atmosphere of air or oxygen. The heating time is 2 hours to 15 hours, the constant temperature time is 2 hours to 20 hours, and the constant temperature is 600-1100° C. to obtain a lithium nickel-cobalt-manganese oxide block material; Step 3, crushing the lithium nickel cobalt manganese oxide block material obtained in step 2 on a double-roll crusher to obtain a lithium nickel cobalt manganese oxide double-roll material; Step 4: The nickel-cobalt-manganese oxide double roller material obtained in step 3 is crushed on a jet mill with a crushing pressure of 0.02-0.7 MPa. After screening, a nickel-cobalt-manganese ternary positive electrode material with multi-element doping to improve safety performance and voltage platform is obtained.

2. The method for preparing a nickel-cobalt-manganese ternary cathode material with improved safety performance and voltage platform by multi-element doping according to claim 1, characterized in that: The lithium source is one of lithium carbonate and lithium hydroxide, and the nickel cobalt manganese hydroxide is Ni 0.5 Co 0.2 Mn 0 .3 (OH)2、Ni 0 .6 Co 0 .1 Mn 0 .3 (OH)2、Ni 0 .7 Co 0 .1 Mn 0 .2 (OH)2、Ni 0 .8 Co 0 .1 Mn 0 .1 (OH)2、Ni 0 .88 Co 0 .8 Mn 0 .4 At least one of (OH)2.

3. The method for preparing a nickel-cobalt-manganese ternary cathode material with improved safety performance and voltage platform by multi-element doping according to claim 1, characterized in that: In step 3, the gap between the rollers is ≤4 μm.

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