Preparation method of nickel-copper-doped lithium manganate positive electrode material and nickel-copper-doped lithium manganate positive electrode material

Abstract

The invention provides a preparation method of a nickel-copper-doped lithium manganate positive electrode material and the nickel-copper-doped lithium manganate positive electrode material. The preparation method specifically comprises the following steps: S1, preparing a nickel-copper-doped lithium manganate positive electrode material precursor; s2, the prepared nickel-copper doped lithium manganate precursor is placed in a Joule heat device, the Joule heat device comprises a conductive substrate and a power source, the nickel-copper doped lithium manganate precursor is calcined by adjusting parameters of the power source to control the sintering temperature, the sintering time and the heating rate, and the nickel-copper doped lithium manganate positive electrode material is obtained. According to the method, nickel and copper transition metal ions are introduced into the lithium manganate positive electrode material, the ginger-Taylor effect and manganese dissolution problems are inhibited, meanwhile, the material can be obtained within several seconds to dozens of seconds by utilizing a Joule thermal method, the time is greatly shortened, the energy consumption is reduced, the cost is reduced, and the lithium manganate positive electrode material prepared by the method has excellent electrochemical performance.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a preparation method and material of a nickel-copper doped lithium manganate positive electrode material. Background Art

[0002] With the rapid development of new energy vehicles and large-scale energy storage technology, the demand for high energy density, high voltage platform and long cycle life cathode materials for lithium-ion batteries is becoming increasingly urgent. Lithium manganese oxide (LiMn2O4) is a popular choice for its abundant resources, low cost, environmental friendliness and high operating voltage (4.1V vs. Li + Lithium manganese oxide (LMO) is considered one of the most promising cathode materials due to its advantages such as high-energy-density ion-polymerization (Li / Li). However, during the charge and discharge process, LMO is prone to lattice distortion caused by the Jahn-Teller effect, as well as manganese dissolution and oxygen vacancy instability. These factors lead to rapid capacity decay and poor cycling performance, severely restricting its practical application.

[0003] To improve the performance of lithium manganese oxide, researchers often use element doping strategies to stabilize the crystal structure. For example, nickel doping can partially replace Mn 3+ , suppressing the Jan-Taylor effect; copper doping, due to its strong bonding ability with oxygen, improves electronic conductivity, reduces oxygen vacancy generation, and enhances structural stability. However, traditional doping methods (such as solid-phase methods) rely on high-temperature and long-term calcination (>10 hours), resulting in high energy consumption, complex processes, and difficulty in precisely controlling doping concentration and distribution uniformity.

[0004] In recent years, Joule heating technology has been widely used due to its ultra-fast heating and cooling (>10 3 ℃ / s) and precise temperature control characteristics provide new ideas for material synthesis and defect control. For example, patent CN119349660A uses Joule thermal shock to synthesize lithium nickel manganese oxide in a few minutes, and by controlling oxygen vacancies and Mn 3+ The content significantly optimizes the cycle performance; Patent CN116885165A uses Joule heat flash evaporation to achieve uniform coating of sulfide solid electrolyte, effectively inhibiting interfacial side reactions. However, existing research focuses on single element doping or coating modification, and the rapid synthesis of nickel and copper dual-element co-doped lithium manganese oxide and its structure-performance correlation mechanism have not been deeply explored. Traditional methods are difficult to achieve uniform Ni / Cu atomic-level doping in a very short time, and cannot effectively balance the contradiction between lattice defects and structural stability. Therefore, the development of an efficient and controllable Joule heat preparation technology to achieve precise doping of nickel and copper dual elements and regulate the lattice defects and electronic structure of lithium manganese oxide is the key to breaking through its performance bottleneck. This technology needs to take into account the feasibility of rapid synthesis, low energy consumption and large-scale production to meet the needs of the next generation of high-power lithium-ion batteries. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a method and material for preparing a nickel-copper doped lithium manganese oxide positive electrode material. By introducing nickel and copper transition metal ions into the lithium manganese oxide positive electrode material, the Jan-Taylor effect and manganese dissolution problems are suppressed. At the same time, the material can be obtained within a few seconds to tens of seconds using the Joule heating method, which greatly shortens the time, reduces energy consumption, and lowers costs. The copper-nickel doped lithium manganese oxide positive electrode material prepared by this method has excellent electrochemical properties.

[0006] To achieve the above technical solution, the present invention provides a method for preparing a nickel-copper doped lithium manganese oxide positive electrode material, which specifically comprises the following steps:

[0007] S1. Preparation of nickel-copper doped lithium manganate positive electrode material precursor: accurately weighing the stoichiometric ratio of lithium source, nickel source, copper source, and manganese source into a planetary ball mill, adding anhydrous ethanol for wet grinding, and ball milling at a speed of 300 r / min for 10 hours. Filtering the precipitate after ball milling, rinsing the balls and sieve, drying, and sieving to obtain nickel-copper doped lithium manganate precursor;

[0008] S2. The prepared nickel-copper doped lithium manganate precursor is placed in a Joule heating device, which includes a conductive substrate and a power supply. The nickel-copper doped lithium manganate precursor is spread flat on the conductive substrate to heat the nickel-copper doped lithium manganate precursor; the two ends of the conductive substrate are connected by alligator clip conductive and thermal conductive components; the nickel-copper doped lithium manganate precursor is calcined by adjusting the power supply parameters to control the sintering temperature, sintering time, and heating rate to obtain a nickel-copper doped lithium manganate positive electrode material.

[0009] Preferably, in step S1, the stoichiometric ratio of Li:Ni:Cu:Mn in the lithium source, nickel source, copper source and manganese source is 1.05:0.01-0.03:0.01-0.03:1.94-1.98.

[0010] Preferably, in step S1, the lithium source is selected from any one or more of lithium carbonate, lithium acetate, lithium nitrate, and lithium hydroxide, the nickel source is selected from any one of nickel oxide, nickel acetate, nickel nitrate, and nickel sulfate, the copper source is selected from any one of copper oxide, copper acetate, copper nitrate, and copper sulfate, and the manganese source is selected from any one of manganese dioxide, manganese trioxide, manganese tetraoxide, and manganese carbonate.

[0011] Preferably, in step S1, the lithium element in the lithium source has an excess of 5%. It was accidentally discovered in the experiment that a small amount of lithium source will volatilize during the sintering process, resulting in insufficient lithium element in the final product. However, lithium element is difficult to replenish during the actual sintering process. Therefore, the lithium element is increased by 5% during the dosing process, which can effectively prevent the lithium source from volatilizing during the sintering process and causing excessive lithium replenishment.

[0012] Preferably, in step S2, the conductive substrate is selected from any one of carbon cloth, carbon paper, iron foil, and tungsten foil.

[0013] Preferably, in step S2, the power supply is any one of a DC power supply and an AC power supply.

[0014] Preferably, in step S2, the heating / cooling rate controlled by adjusting the power supply parameters is 200-400°C / s.

[0015] Preferably, in step S2, the pre-sintering temperature is 300-500°C, the pre-sintering time is 2-20s; the formal sintering temperature is 700-900°C, the formal sintering time is 2-20s, and the sintering atmosphere is any one of air, nitrogen, and argon.

[0016] Preferably, in step S2, the product nickel-copper doped lithium manganate positive electrode material has the form of LiNi x Cu x Mn 2-2x The chemical formula of O4 is 0<x<0.5.

[0017] The present invention also discloses a nickel-copper doped lithium manganate positive electrode material, which is prepared based on any of the above methods.

[0018] The beneficial effects of the method for preparing a nickel-copper doped lithium manganate positive electrode material provided by the present invention are:

[0019] (1) By introducing nickel and copper cation co-doped lithium manganese oxide positive electrode materials, the inherent Jan-Taylor effect and manganese dissolution problems of lithium manganese oxide positive electrode materials are alleviated. Due to the synergistic effect between nickel and copper ions and the small radius of nickel and copper ions, after replacing part of the manganese ions, the content of trivalent manganese ions is reduced, its crystal structure is stabilized, and the manganese dissolution problem caused by its disproportionation reaction is suppressed, thereby improving the electrochemical performance of lithium manganese oxide positive electrode materials.

[0020] (2) Joule heat can be directly converted into thermal energy without the need for an external heat source, thereby achieving rapid sintering and rapid cooling of lithium manganese oxide positive electrode materials. Compared with the traditional muffle furnace sintering method, it greatly shortens the sintering time, reduces energy consumption, reduces costs, improves work efficiency, and breaks through the bottleneck of traditional sintering technology.

[0021] (3) The lithium manganese oxide positive electrode material particles prepared by Joule heat have smaller submicron particles and truncated polyhedral morphology, which widens the lithium ion diffusion channel, shortens the distance of lithium ion transmission, accelerates the charge and discharge speed, and improves the rate performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The figure is a flow chart for preparing the nickel-copper doped lithium manganate positive electrode material of the present invention.

[0023] Figure 2 This is the XRD pattern of Example 2 of the present invention.

[0024] Figure 3 This is the SEM image of Example 2 of the present invention.

[0025] Figure 4 This is a charge and discharge curve diagram of Example 2 of the present invention.

[0026] Figure 5 Graph showing the cycle performance of Example 2 of the present invention and all comparative examples. DETAILED DESCRIPTION

[0027] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary persons in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1:

[0029] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.01:0.01:1.98, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0030] Step (2): placing the obtained precursor material on a conductive substrate, and controlling the heating and cooling rate to 200°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 750°C, and the formal sintering time to 18s by adjusting the power supply parameters in an air atmosphere. After the reaction is completed, the nickel-copper doped lithium manganese oxide positive electrode material is obtained by passing through a 300-mesh sieve.

[0031] Example 2:

[0032] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.02:0.02:1.96, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0033] Step (2): placing the obtained precursor material on a conductive substrate, and controlling the heating and cooling rate to 300°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 800°C, and the formal sintering time to 15s by adjusting the power supply parameters in an air atmosphere. After the reaction is completed, the material is sieved through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganese oxide positive electrode material.

[0034] Example 3:

[0035] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.03:0.03:1.94, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and sieve, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganese oxide material precursor.

[0036] Step (2): placing the obtained precursor material on a conductive substrate, and adjusting the power supply parameters in an air atmosphere to control the heating and cooling rate to 400°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 850°C, and the formal sintering time to 12s. After the reaction is completed, the nickel-copper doped lithium manganese oxide positive electrode material is obtained by passing through a 300-mesh sieve.

[0037] Example 4:

[0038] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.01:0.01:1.98, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0039] Step (2): placing the obtained precursor material on a conductive substrate, and controlling the heating and cooling rate to 300°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 800°C, and the formal sintering time to 15s by adjusting the power supply parameters in an air atmosphere. After the reaction is completed, the material is sieved through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganese oxide positive electrode material.

[0040] Example 5:

[0041] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.02:0.02:1.96, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0042] Step (2): placing the obtained precursor material on a conductive substrate, and controlling the heating and cooling rate to 200°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 750°C, and the formal sintering time to 18s by adjusting the power supply parameters in an air atmosphere. After the reaction is completed, the nickel-copper doped lithium manganese oxide positive electrode material is obtained by passing through a 300-mesh sieve.

[0043] Example 6:

[0044] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.03:0.03:1.94, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and sieve, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganese oxide material precursor.

[0045] Step (2): placing the obtained precursor material on a conductive substrate, and controlling the heating and cooling rate to 200°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 750°C, and the formal sintering time to 18s by adjusting the power supply parameters in an air atmosphere. After the reaction is completed, the nickel-copper doped lithium manganese oxide positive electrode material is obtained by passing through a 300-mesh sieve.

[0046] Example 7:

[0047] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.01:0.01:1.98, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0048] Step (2): placing the obtained precursor material on a conductive substrate, and adjusting the power supply parameters in an air atmosphere to control the heating and cooling rate to 400°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 850°C, and the formal sintering time to 12s. After the reaction is completed, the nickel-copper doped lithium manganese oxide positive electrode material is obtained by passing through a 300-mesh sieve.

[0049] Example 8:

[0050] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.02:0.02:1.96, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0051] Step (2): placing the obtained precursor material on a conductive substrate, and adjusting the power supply parameters in an air atmosphere to control the heating and cooling rate to 400°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 850°C, and the formal sintering time to 12s. After the reaction is completed, the nickel-copper doped lithium manganese oxide positive electrode material is obtained by passing through a 300-mesh sieve.

[0052] Example 9:

[0053] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.03:0.03:1.94, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and sieve, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganese oxide material precursor.

[0054] Step (2): placing the obtained precursor material on a conductive substrate, and controlling the heating and cooling rate to 300°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 800°C, and the formal sintering time to 15s by adjusting the power supply parameters in an air atmosphere. After the reaction is completed, the material is sieved through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganese oxide positive electrode material.

[0055] Comparative Example 1:

[0056] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1.05:0.02:0.02:1.96, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0057] Step (2): The obtained precursor material is placed in a muffle furnace, sintered at 500°C for 5h and 800°C for 12h at a heating rate of 5°C / min. After the reaction is completed, the precursor material is sieved through a 300-mesh sieve to obtain a nickel-copper doped lithium manganate positive electrode material.

[0058] Compared with Example 2, this comparative example adopts the same raw materials and preparation method as Example 2 except that the sintering method is changed to the traditional muffle furnace sintering method.

[0059] Comparative Example 2:

[0060] Step (1): Accurately weigh Li2CO3 and Mn3O4 with a stoichiometric ratio of Li:Mn of 1.05:2, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0061] Step (2): placing the obtained precursor material on a conductive substrate, and controlling the heating and cooling rate to 300°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 800°C, and the formal sintering time to 15s by adjusting the power supply parameters in an air atmosphere. After the reaction is completed, the material is sieved through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganese oxide positive electrode material.

[0062] Compared with Example 2, this comparative example does not use NiO and CuO doping modification, that is, the doping amount is 0, and the remaining raw materials and preparation method are the same as those in Example 2.

[0063] Comparative Example 3:

[0064] Step (1): Accurately weigh Li2CO3 and Mn3O4 with a stoichiometric ratio of Li:Mn of 1.05:2, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0065] Step (2): The obtained precursor material is placed in a muffle furnace, sintered at 500°C for 5h and 800°C for 12h at a heating rate of 5°C / min. After the reaction is completed, the precursor material is sieved through a 300-mesh sieve to obtain a nickel-copper doped lithium manganate positive electrode material.

[0066] Compared with Example 2, this comparative example does not use NiO and CuO doping modification and changes the sintering method, that is, the doping amount is 0 and the traditional muffle furnace sintering method is adopted. The other raw materials and preparation methods are the same as those in Example 2.

[0067] Comparative Example 4:

[0068] Step (1): Accurately weigh Li2CO3, NiO, CuO, and Mn3O4 with a stoichiometric ratio of Li:Ni:Cu:Mn of 1:0.02:0.02:1.96, add the weighed raw materials into a ball mill, and add 40 ml of anhydrous ethanol as a medium for wet grinding, ball milling at a speed of 300 rpm / min for 30 minutes, let it stand for 5 minutes, and cycle forward and reverse in sequence until the ball milling is completed for 10 hours. Filter the precipitate after ball milling, rinse the balls and screen, put it into a vacuum drying oven at 120°C and dry it for 12 hours, and pass it through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganate material precursor.

[0069] Step (2): placing the obtained precursor material on a conductive substrate, and controlling the heating and cooling rate to 300°C / s, the pre-sintering temperature to 500°C, the pre-sintering time to 9s, the formal sintering temperature to 800°C, and the formal sintering time to 15s by adjusting the power supply parameters in an air atmosphere. After the reaction is completed, the material is sieved through a 300-mesh sieve to obtain a nickel-copper-doped lithium manganese oxide positive electrode material.

[0070] Compared with Example 2, this comparative example is the same as Example 2 except that the Li element is not excessive by 5%, that is, the stoichiometric ratio of Ni:Cu:Mn elements is 1:0.02:0.02:1.96. The other raw materials and preparation methods are the same as those of Example 2.

[0071] Performance Testing

[0072] The samples obtained in the examples and comparative examples were used as active materials. The active materials, conductive agent acetylene black and binder polyvinylidene fluoride (PVDF) were mixed uniformly in a mass ratio of 8:1:1. An appropriate amount of N-methylpyrrolidone (NMP) was added to form a fluid slurry, which was then coated on aluminum foil and dried in a vacuum at 120°C for 12 hours. The slurry was used as the working electrode. The metal lithium sheet was used as the negative electrode, and 1 mol·L -1 A mixed solution of LiPF6 in ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DEC) (volume ratio of 1:1:1) was used as the electrolyte, and Celgard 2500 was used as the separator. CR2032 button-type cells were fabricated in an argon-filled glove box. The battery's charge-discharge cycling performance was tested within the 3-4.3V electrochemical window using a BlueDian battery testing system.

[0073] The test results are as follows

[0074] Table 1 Comparison of electrochemical properties of positive electrode materials in Examples 1 to 9 and Comparative Examples 1 to 4

[0075]

[0076] As can be seen from the experimental data in Table 1, the initial and post-cycle discharge specific capacity and capacity retention of Examples 1-9, which introduce nickel-copper ion doping and employ Joule heat, are superior to those of Comparative Examples 1-3, which have changed the sintering method and are undoped. The capacity retention rates of the positive electrode materials prepared in Examples 1-9 are 89.87%, 91.55%, 89.88%, 89.79%, 89.08%, 88.45%, 89.02%, 88.17%, and 89.17%, respectively; it can be seen that Example 2 exhibits the best electrochemical performance, indicating that the doping of nickel-copper ions combined with the sintering method employing Joule heat can improve the electrochemical performance of the material; the discharge specific capacity and capacity retention of Examples 1-9 are superior to those of Comparative Examples 1 and 3, as the latter employ a traditional muffle furnace sintering method, which is not conducive to the formation of lattice defects on the surface of the material and cannot effectively improve the structural stability of the material. In addition, the discharge specific capacity and capacity retention rate of Examples 1-9 are also better than those of Comparative Example 2, indicating that the doping of nickel and copper ions can improve the electrochemical properties of the material. The introduction of nickel ions can stabilize the crystal structure of the material, while the introduction of copper ions can improve the conductivity of the material, thereby improving its electrochemical performance. It can be seen that the method of ion co-doping combined with Joule heat rapid sintering of the present invention is crucial for forming a positive electrode material with excellent electrochemical properties. If one of them is missing, the effect will be weak.

[0077] In addition, it was accidentally discovered in the experiment that a small amount of lithium source would volatilize during the sintering process, resulting in insufficient lithium in the final product, reduced reversible capacity of the material, decreased structural stability, and poor cycle performance; and lithium is difficult to replenish during the actual sintering process. From Table 1, it was found that the initial discharge specific capacity and capacity retention rate of Example 2 were better than those of Comparative Example 4: Therefore, an excess of 5% lithium in the dosing process can effectively prevent the volatilization of the lithium source during the sintering process, thereby ensuring the electrochemical performance of the product.

[0078] In summary, the present invention provides a nickel-copper doped lithium manganese oxide positive electrode material and preparation method based on rapid Joule heating. First, the lithium source, nickel source, copper source, and manganese source are ball-milled and then sieved, which can refine the crystal particles of the raw materials and enable the transition metal ions to more effectively penetrate into the lattice, thereby improving the structural stability and conductivity of the material; then, the ball-milled and sieved precursor material is placed on a Joule heat conductive substrate and subjected to rapid Joule heat sintering to improve the material lattice defects. After the reaction is completed, the material is further sieved to make the particles more uniform and the particle size smaller, thereby further improving the crystal structure stability and electrochemical performance of the positive electrode material.

[0079] The above description is only a preferred embodiment of the present invention and does not constitute any formal limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the spirit and technical solution of the present invention, use the methods and technical contents disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a nickel-copper doped lithium manganate positive electrode material, characterized in that The specific steps include: S1. Preparation of nickel-copper doped lithium manganate positive electrode material precursor: accurately weighing the lithium source, nickel source, copper source, and manganese source in a stoichiometric ratio and placing them in a ball mill, adding anhydrous ethanol for wet grinding, and ball milling at a speed of 300 r / min for 10 hours. Filtering the precipitate after ball milling, washing the balls and sieve, drying, and sieving to obtain a nickel-copper doped lithium manganate precursor; S2. The prepared nickel-copper doped lithium manganate precursor is placed in a Joule heating device, which includes a conductive substrate and a power supply. The nickel-copper doped lithium manganate precursor is spread flat on the conductive substrate to heat the nickel-copper doped lithium manganate precursor; the two ends of the conductive substrate are connected by alligator clip conductive and thermal conductive components; the nickel-copper doped lithium manganate precursor is calcined by adjusting the power supply parameters to control the sintering temperature, sintering time, and heating rate to obtain a nickel-copper doped lithium manganate positive electrode material.

2. The method for preparing nickel-copper-doped lithium manganate positive electrode material according to claim 1, wherein: In the step S1, the stoichiometric ratio of Li:Ni:Cu:Mn in the lithium source, nickel source, copper source and manganese source is 1.05:0.01-0.03:0.01-0.03:1.94-1.

98.

3. The method for preparing nickel-copper-doped lithium manganate positive electrode material according to claim 2, wherein: In step S1, the lithium source is selected from any one or more of lithium carbonate, lithium acetate, lithium nitrate, and lithium hydroxide; the nickel source is selected from any one of nickel oxide, nickel acetate, nickel nitrate, and nickel sulfate; the copper source is selected from any one of copper oxide, copper acetate, copper nitrate, and copper sulfate; and the manganese source is selected from any one of manganese dioxide, manganese trioxide, manganese tetraoxide, and manganese carbonate.

4. The method for preparing nickel-copper-doped lithium manganate positive electrode material according to claim 1, wherein: In the step S1, the lithium source contains an excess of 5% lithium.

5. The method for preparing nickel-copper-doped lithium manganate positive electrode material according to claim 1, wherein: In step S2, the conductive substrate is selected from any one of carbon cloth, carbon paper, iron foil, and tungsten foil.

6. The method for preparing nickel-copper-doped lithium manganate positive electrode material according to claim 1, wherein: In step S2, the power supply is any one of a DC power supply and an AC power supply.

7. The method for preparing nickel-copper-doped lithium manganate positive electrode material according to claim 1, wherein: In step S2, the heating / cooling rate controlled by adjusting the power supply parameters is 200-400° C. / s.

8. The method for preparing nickel-copper-doped lithium manganate positive electrode material according to claim 1, wherein: In step S2, the pre-sintering temperature is 300-500°C, the pre-sintering time is 2-20s; the main sintering temperature is 700-900°C, the main sintering time is 2-20s, and the sintering atmosphere is any one of air, nitrogen, and argon.

9. The method for preparing nickel-copper-doped lithium manganate positive electrode material according to claim 1, wherein: In step S2, the product nickel-copper doped lithium manganate positive electrode material has the form of LiNi x Cu x Mn 2-2x The chemical formula of O4 is 0<x<0.

5.

10. A nickel-copper doped lithium manganate positive electrode material, characterized in that: Prepared by any one of the methods described in claims 1-9.

Images