CN104953199A - Metal doping LiMn(1-x-y)NixCoyO2 compounded by lithium ion battery positive electrode waste, as well as preparation method and application of metal doping LiMn(1-x-y)NixCoyO2 - Google Patents

Abstract

The invention provides a metal-doped nickel-cobalt lithium manganese oxide synthesized by using the positive electrode waste of lithium-ion batteries and its preparation method and application. The preparation method comprises: removing the binder and conductive agent in the positive electrode waste of lithium-ion batteries, Obtain the positive electrode active material; measure the elemental composition of the positive electrode active material; adjust the content of one or at least two of Ni, Co, Mn or M in the positive electrode active material so that the molar ratio conforms to the molecular formula LiNi _x Mn _y Co _1–x The molar ratio of Ni, Co, Mn and M in _–y–z M _z O ₂ is used to obtain the precursor powder of positive electrode active material; then add lithium source, and use high-temperature solid-state reaction to obtain metal-doped nickel-cobalt lithium manganese oxide. The method has wide applicability, simple operation, low cost, avoids secondary pollution, realizes a short-range cleaning cycle of positive electrode active materials in waste lithium ion batteries, and the prepared metal-doped nickel-cobalt lithium manganese oxide has excellent electrochemical performance.

Description

Metal-doped nickel-cobalt lithium manganese oxide synthesized by lithium-ion battery positive electrode waste and its preparation method and use

technical field

The invention belongs to the technical field of secondary resource recycling and circular economy, and relates to a method for recycling and recycling lithium-ion battery positive electrode waste, in particular to a metal-doped nickel-cobalt lithium manganate synthesized by using lithium-ion battery positive electrode waste and Its preparation method and use.

Background technique

Due to the advantages of high charging voltage, high energy density, long cycle life, good safety, no memory effect and small self-discharge, lithium-ion batteries have been widely used in mobile phones, notebook computers, video cameras, digital batteries since the 1990s. Portable electronics such as cameras and medical devices. With the rapid development of lithium-ion battery technology in recent years, it has become a strong competitor for hybrid electric vehicles, pure electric vehicles and smart grid power supplies. At the same time, due to the accelerated update of consumer electronics and the further application of lithium-ion batteries in the fields of transportation and smart grids, the demand for lithium-ion batteries will continue to grow in the next few years.

With the widespread application of lithium-ion batteries, a large number of waste lithium-ion batteries and the waste generated in the production process will be produced. Different from municipal solid waste, these waste lithium-ion batteries and their production waste contain toxic and harmful heavy metals and organic electrolytes. If not handled properly, these wastes will pose a serious threat to the ecological environment and human health. In addition, these wastes contain an average of 12% to 18% cobalt, 1.2% to 1.8% lithium, 8% to 10% copper, 4% to 8% aluminum and about 30% shell alloys, all of which are lithium Raw material for ion battery production. Therefore, if the metals in these waste lithium-ion batteries and their production waste can be recovered efficiently, and the closed-loop circulation of these metals in the production process can be realized, it can not only avoid the threat to the environment and human body, but also promote the sustainable development of the lithium-ion battery industry. Sustainable development and industrial upgrading.

Lithium-ion battery anode materials account for about 30% to 50% of the entire battery production cost, which is the part with the highest resource value in lithium-ion batteries, and is also the focus and difficulty of recycling waste lithium-ion batteries. Lithium cobaltate has good electrochemical properties and is the most common positive electrode material in commercially available lithium-ion batteries. The existing waste lithium-ion battery recycling technology is mainly aimed at lithium-ion batteries in which lithium cobaltate is the positive electrode active material. However, due to the disadvantages of high cost, high toxicity of cobalt and limited resources of lithium cobalt oxide, lithium nickel oxide (LiNiO ₂ ), lithium manganate (LiMnO ₂ ), binary composite Cathode materials (LiNi _x Co _{1– x} O ₂ , LiNi _x Mn _1–x O ₂ , LiCo _1–x Mn _x O ₂ ), ternary composite cathode materials (LiNi _x Co _y Mn _l–x–y O ₂ , LiNi _x Co _y All _l–x–y O ₂ ) and lithium manganese oxide (LiMn ₂ O ₄ ) with a spinel structure have been developed successively. Among them, due to the advantages of high reversible charge and discharge capacity, good safety performance, and low cost of use, the ternary composite cathode material is expected to promote the further application of lithium-ion batteries in power batteries, energy storage power stations and other fields. However, at present, the recovery technology of waste lithium ion batteries based on the above-mentioned newly developed positive electrode active materials is very scarce, so it is urgent to develop waste lithium ion battery recycling technologies for the above-mentioned positive electrode active materials, especially mixed positive electrode active materials.

CN 103199320A discloses a method for recycling nickel-cobalt-manganese ternary positive electrode materials. The method is as follows: heat treatment is used to remove the binder to recover nickel-cobalt-manganese ternary positive electrode materials, and then reductive acid leaching, addition of alkali to remove aluminum and Sodium hydroxide is used as a precipitating agent. The technical route for preparing nickel-cobalt-manganese ternary precursors by co-precipitation method is to recover nickel-cobalt-manganese ternary positive electrode materials. However, the process of this method is too complicated, and the cost is high, and it will inevitably produce waste water containing heavy metals, so corresponding sewage treatment facilities are required. Chen Guchun and others studied the recovery of nickel, cobalt and manganese in waste lithium batteries and the preparation of positive electrode materials LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ , using waste lithium batteries as raw materials, after manual shelling, battery cores Grinding, heat treatment, and sieving to obtain powder containing spent positive electrode materials; powder is leached through H ₂ SO ₄ +H ₂ O ₂ solution - iron removal by jarosite method - aluminum removal with ammonium bicarbonate - copper extraction with N902 - addition of ingredients Ratio-co-precipitation synthesis precursor-calcination process, and LiCo _1/3 Ni _1/3 Mn _1/3 O ₂ cathode material was synthesized (Journal of Inorganic Chemistry, 2011, 27(10), 1987-1992). The method realizes the recycling of waste lithium-ion batteries, but the method also has problems such as complicated process and secondary pollution.

In order to improve the electrochemical performance of the positive electrode active material of lithium-ion batteries, technologies such as transition metal ion doping and compound coating are usually used to modify the positive electrode active material. Therefore, the metal composition of lithium-ion batteries in the future will become more and more complex, which will lead to the separation and recovery of positive electrode waste will contain some other metals. At the same time, during the disassembly process of lithium-ion batteries, the aluminum and copper in the positive and negative current collectors may also be mixed into the separated positive electrode materials. All of the above pose new challenges for the research and development of waste lithium-ion battery recycling technology.

So far, there is no short-range cleaning cycle technology that can recycle cathode scrap mixed with impurity metals, especially mixed cathode scrap.

Contents of the invention

In view of the deficiencies in the prior art, in order to solve the problems of long process flow, high processing cost, narrow scope of application, secondary pollution, etc. of waste lithium ion battery recycling technology and to fill the gaps in related technologies, the purpose of the present invention is to provide a lithium ion battery Metal-doped nickel-cobalt lithium manganese oxide synthesized from battery positive electrode waste and its preparation method and application, the method overcomes the shortcomings of the prior art and improves the electrochemical performance of lithium ion battery positive electrode materials.

For reaching this purpose, the present invention adopts following technical scheme:

In one aspect, the present invention provides a method for synthesizing metal-doped nickel-cobalt lithium manganese oxide by using lithium-ion battery positive electrode waste, and the metal-doped nickel-cobalt lithium manganese oxide has the following composition: LiNi _x Mn _y Co _{1-x- y–z} M _z O ₂ , where M is any one or at least two of Cu, Al, Fe, Mg, Cr, Ti, Ce or Y, 0<x<1, 0<y<1, 0 <z<0.1, and 0<x+y+z<1;

The method comprises the steps of:

(1) remove the binder and the conductive agent in the positive electrode waste of the lithium ion battery to obtain the positive electrode active material;

(2) Determination of the elemental composition of the positive electrode active material;

(3) According to the element composition of the positive electrode active material, adjust the content of one or at least two of Ni, Co, Mn or M in the positive electrode active material so that the molar ratio conforms to the molecular formula LiNi _x Mn _y Co _{1–x–y -zMzO2In} the _molar ratio of Ni, Co, _Mn and M, and obtain positive electrode active material precursor powder;

(4) Adding a lithium source to the positive electrode active material precursor powder, and using a high-temperature solid-state reaction to obtain metal-doped nickel-cobalt lithium manganese oxide.

According to the method of the present invention, the positive electrode material separated from the positive electrode waste of lithium ion battery is subjected to high-temperature roasting to obtain the positive electrode active material; then one or at least two of Ni, Co, Mn or M in the positive electrode active material are adjusted Content, so that the element composition and content meet the target product LiNi _x Mn _y Co _{1–x–y–z} M _z O ₂ , to obtain the positive active material precursor powder; then add lithium source to the obtained precursor powder, through Synthesis of metal-doped nickel-cobalt-lithium manganese oxide by high-temperature solid-state sintering.

The method for synthesizing metal-doped nickel-cobalt lithium manganese oxide by using the positive electrode waste of lithium-ion batteries provided by the present invention has wide application range, simple operation and low cost, and avoids heavy metals produced by recycling the positive electrode waste of lithium-ion batteries by co-precipitation technology. The secondary pollution of high-concentration ammonia-nitrogen wastewater to the environment has realized the short-range cleaning cycle of positive active materials in waste lithium-ion batteries.

The molecular formula of the metal-doped nickel-cobalt lithium manganese oxide is: LiNi _x Mn _y Co _1-x-y-z M _z O ₂ . Among them, M is any one or a combination of at least two of Cu, Al, Fe, Mg, Cr, Ti, Ce or Y. Typical but non-limiting combinations are: Cu and Al, Al and Mg, Ce and Y, Mg and Ti, Al, Mg and Cr, Fe, Mg and Cr, Cr, Ti, Ce and Y, etc.; 0<x<1, 0<y<1, 0<z<0.1, and 0<x+ y+z<1; if x is 1/2, 1/3, 1/4, 1/5, 1/6, 1/7 or 1/10, etc., y is 1/2, 1/3, 1/ 4, 1/5, 1/6, 1/7 or 1/10 etc., z is 1/20, 1/30, 1/40, 1/50, 1/60, 1/70 or 1/80 etc.

The positive electrode active material in step (1) is: nickel-based oxide, cobalt-based oxide, manganese-based oxide, M-doped nickel-based oxide, M-doped cobalt-based oxide, M-doped Any one or at least two of manganese-based oxides, nickel-based oxides coated with M compounds, cobalt-based oxides coated with M compounds, or manganese-based oxides coated with M compounds The combination. Typical but non-limiting positive electrode active material combinations include: nickel-based oxides and cobalt-based oxides, manganese-based oxides and M-doped nickel-based oxides, M-doped cobalt-based oxides and M-doped Miscellaneous manganese-based oxides, M compound-coated modified nickel-based oxides and M compound-coated modified cobalt-based oxides or M compound-coated modified manganese-based oxides, nickel-based oxides and cobalt-based oxides, etc. The M compound is a compound containing metal M.

Preferably, the M is derived from impurity metals mixed in the process of separating the positive electrode waste of lithium-ion batteries to obtain the positive electrode active material or metals introduced by the positive electrode active material due to doping or coating modification.

Preferably, the M is derived from the metal introduced by the positive electrode active material due to doping or coating modification.

The mass fraction of carbon in the positive electrode active material in step (1) is lower than 0.001%.

Preferably, step (1) obtains the positive electrode active material by roasting the lithium ion battery positive electrode waste.

Preferably, the calcination temperature is 400-1000°C, such as 500°C, 600°C, 700°C, 800°C, 900°C or 950°C, etc., preferably 500-800°C.

Preferably, the calcination time is 2-8h, such as 2.5h, 3h, 4h, 5h, 6h, 7h or 7.5h, etc., preferably 4-6h.

Preferably, the calcination is carried out in a high temperature furnace.

Step (2) adding the positive electrode active material into a strong acid solution, heating and digesting, and then measuring the elemental composition of the positive electrode active material. The strong acidic solution can be an inorganic strong acidic solution or an organic strong acidic solution, and the strong acidic solution can dissolve the metal elements in the positive electrode active material, preferably aqua regia.

Preferably, the heating and digestion time is 1 to 6 hours, such as 2 hours, 3 hours, 4 hours, 5 hours or 5.5 hours.

Preferably, step (2) uses ICP-OES to determine the elemental composition of the positive electrode active material.

Step (3) adding any one or at least two of Ni source, Co source, Mn source or M source to the positive electrode active material to adjust the content of elements in the positive electrode active material.

Preferably, the source of Ni, Co, Mn or M is independently an oxide, chloride, sulfate, nitrate, acetate or oxalate of Ni, Co, Mn or M.

Preferably, the positive electrode active material described in step (3) is ground with the added Ni source, Co source, Mn source or M source to obtain a positive electrode active material precursor powder, and the grinding time is 8 to 24 hours, such as 9h, 10h, 12h, 15h, 17h, 18h, 19h, 20h, 22h or 23h, etc. The grinding can achieve the effect of uniformly mixing the positive electrode active material with the Ni source, Co source, Mn source or M source, that is, the material is evenly distributed at any point in the ground mixture without accumulation, typical but not Restrictive grinding equipment includes ball mills and the like.

The lithium source described in step (4) is lithium carbonate, lithium chloride, lithium sulfate, lithium nitrate, lithium acetate or lithium oxalate, or a mixture of at least two, typical but non-limiting mixtures are: lithium carbonate and lithium oxalate Lithium chloride, lithium sulfate and lithium nitrate, lithium acetate and lithium oxalate or lithium carbonate, lithium chloride and lithium acetate, etc.

Preferably, the lithium source added in step (4) makes the ratio of the amount of Li material to the total material amount of Ni, Co, Mn and M be 1.05 to 1.1, i.e. n(Li)/(n(Ni) +n(Co)+n(Mn)+n(M))=1.05～1.1, such as the ratio of the amount of substances is 1.06, 1.07, 1.08, 1.09 or 1.1, etc. Adding an excess of lithium source is to avoid the volatilization of lithium in the high-temperature solid-state reaction, resulting in a ratio of Li to the total amount of Ni, Co, Mn and M that is less than 1:1.

Preferably, the temperature of the high-temperature solid-state reaction in step (4) is 800-900°C, such as 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C or 890°C, etc., The reaction time is 15-20h, such as 16h, 17h, 17.5h, 18h, 19h or 19.5h.

Preferably, the heating rate during the high-temperature solid-state reaction in step (4) is 2 to 10°C·min ^-1 , such as 3°C·min ^-1 , 4°C·min ^-1 , 5°C·min ^-1 , 6°C·min -1 , ℃·min ^-1 , 7°C·min ^-1 , 8°C·min ^-1 or 9°C·min ^-1 , etc.

Preferably, the high-temperature solid-state reaction in step (4) is carried out in an aerobic atmosphere.

Preferably, the high-temperature solid-state reaction in step (4) is as follows: after raising the temperature to 800-900°C at a rate of 2-10°C·min ^-1 , roasting at a constant temperature in an aerobic atmosphere for 15-20 hours, and then heating at a temperature of 1-5 The temperature is lowered at a rate of ℃·min ^-1 to 10-60 ℃ to obtain metal-doped nickel-cobalt lithium manganese oxide.

Step (4) Grinding and sieving the lithium source and the precursor powder of the positive electrode active material, and then performing a high-temperature solid-state reaction.

Preferably, the grinding is performed on a ball mill.

Preferably, the mesh of the sieve is 200-1000 mesh, such as 300 mesh, 500 mesh, 600 mesh, 700 mesh, 800 mesh or 900 mesh.

As a preferred technical solution, the present invention provides a method for synthesizing metal-doped nickel-cobalt lithium manganese oxide using lithium-ion battery positive electrode waste, the method comprising the following steps:

(1) placing the separated lithium-ion battery positive electrode waste material in a high-temperature furnace for roasting, removing the binder and conductive agent therein to obtain the positive electrode active material;

(2) Determining the elemental composition of the positive active material;

(3) According to the element composition of the positive electrode active material, adjust the content of Ni, Co, Mn or M in the positive electrode active material so that the molar ratio conforms to the molecular formula LiNi _x Mn _y Co _{1–x–y–z} M _z O ₂ In the molar ratio of Ni, Co, Mn and M, the positive electrode active material precursor powder is obtained;

(4) Add a lithium source to the positive electrode active material precursor powder so that the molar ratio of Li to the sum of Ni, Co, Mn and M is 1.05 to 1.1, and then raise the temperature to 800 at a rate of 2 to 10°C·min ^-1 After ~900°C, it is roasted at a constant temperature in an oxygen atmosphere for 15-20 hours, and then cooled to 10-60°C at a rate of 1-5°C·min ^-1 to obtain metal-doped nickel-cobalt lithium manganese oxide.

In another aspect, the present invention provides a metal-doped nickel-cobalt lithium manganese oxide prepared by the above-mentioned method.

The present invention also provides a use of the metal-doped nickel-cobalt lithium manganese oxide prepared by the above-mentioned method, which is used in the field of positive electrode materials for lithium-ion batteries.

Compared with prior art, the beneficial effect of the present invention is:

(1) The method provided by the present invention utilizes lithium-ion battery anode waste to synthesize metal-doped nickel-cobalt lithium manganese oxide directly using the impurity metal in the separated positive electrode material as a doping element to synthesize metal-doped nickel-cobalt lithium manganese oxide, Not only the process flow is shortened, the cost of impurity removal is reduced, but more importantly, the electrochemical performance of lithium nickel cobalt manganese oxide is improved through metal doping.

(2) The method for synthesizing metal-doped nickel-cobalt lithium manganese oxide by using lithium-ion battery positive electrode waste provided by the present invention adopts high-temperature solid-phase method to synthesize metal-doped nickel-cobalt lithium manganese oxide, which avoids the generation of co-precipitation method in the existing process The risk of environmental pollution caused by high-concentration ammonia nitrogen wastewater containing heavy metals saves the investment in additional wastewater treatment facilities.

(3) The method for synthesizing metal-doped nickel-cobalt lithium manganese oxide by using the positive electrode waste of lithium ion batteries provided by the present invention has a wide range of applications, and is suitable for large-scale treatment of positive electrode waste of lithium ion batteries.

Description of drawings

Fig. 1 is the LiNi _1/3 Mn _1/3 Co _1/3-1/20 Al _1/20 O synthesized in embodiment ₁ The XRD pattern of positive electrode active material;

Fig. 2 is the SEM image of LiNi _1/3 Mn _1/3 Co _1/3-1/20 Al _1/20 O ₂ positive electrode active materials synthesized in embodiment 1;

Fig. 3 is LiNi _1/3 Mn _1/3 Co _1/3-1/20 Al _1/20 O ₂ synthesized in embodiment 1 first charge and discharge curve of positive electrode active material;

Fig. 4 is the LiNi _1/3 Mn _1/3 Co _1/3-1/20 Al _1/20 O ₂ synthesized in embodiment 1 cycle performance curve of positive electrode active material;

FIG. 5 is a Coulombic efficiency curve of the LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ cathode active material synthesized in Example 1 during the charge-discharge cycle.

Detailed ways

The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and through specific implementation methods. It should be clear to those skilled in the art that the embodiments are only for helping to understand the present invention, and should not be regarded as specific limitations on the present invention.

Example 1

Take 10 g of nickel-cobalt lithium manganate positive electrode material containing a small amount of impurity aluminum separated by the method described in CN102751549B, and synthesize an aluminum-doped nickel-cobalt lithium manganate positive electrode active material according to the following steps, the specific steps are as follows:

(1) Put the separated nickel cobalt lithium manganese oxide positive electrode waste containing a small amount of impurity aluminum in a constant temperature resistance furnace at 600 ° C for 5 hours to obtain the positive active material, and use an infrared carbon-sulfur analyzer to detect the mass fraction of carbon in the positive active material If it is less than 0.001%, it indicates that the conductive agent and binder in the positive electrode active material are completely removed.

(2) Add 0.5 g of the positive electrode active material obtained in step (1) into aqua regia, heat and digest for 2 hours, and then use ICP-OES to analyze and measure the metal components in it. The specific results are shown in Table 1.

Table 1 The mass percentage of metal in the positive electrode active material

Metal Ni co mn Li Al Mass content (wt.%) 21.36 22.51 20.93 8.27 1.73

(3) According to the mass content of the metal in the positive electrode active material and the molecular formula of the aluminum-doped nickel-cobalt lithium manganate to be synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ in Ni , Mn, Co and Al atomic number ratio, mixed with nickel nitrate hexahydrate, cobalt nitrate hexahydrate, manganese nitrate tetrahydrate or aluminum hydroxide so that the molar ratios of Ni to Mn, Ni to Co and Ni to Al are 1 respectively :1, 1.176:1 and 6.667:1, and then grind for 10h with a ball mill, so that the above-mentioned mixture is fully ground and mixed uniformly to obtain the positive electrode active material precursor powder.

(4) add lithium carbonate to the positive electrode active material precursor powder that step (3) obtains, make the ratio of the amount of substance of Li and the total amount of substance of Ni, Co, Mn and Al be 1.05～1.1, use After the ball mill is fully ground and mixed evenly, pass through a 200-mesh standard sieve, place the sieved material in a high-temperature furnace, heat up to 900°C at a rate of 2°C min ^-1 , and then roast it at a constant temperature in an aerobic atmosphere for 15 hours, then The temperature was lowered to 10°C at a rate of 5°C·min ^-1 to obtain an aluminum-doped nickel-cobalt lithium manganate cathode active material LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ . Figure 1 is the XRD pattern of the synthesized aluminum-doped nickel-cobalt lithium manganate cathode active material LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ ; Figure 2 is the synthesized aluminum-doped SEM images of LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ doped nickel-cobalt lithium manganate cathode active material.

It can be seen from Figure 1 that the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ cathode active material has sharp diffraction peaks, no impurity phases, and well-developed crystals, with a typical The layered structure of α-NaFeO ₂ belongs to the hexagonal crystal system; as can be seen from Figure 2, the morphology of the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ positive electrode active material is similar to Spherical, the primary particle size is 1μm–2μm, and the secondary particle is an aggregate of primary particles.

A button battery was assembled using the LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ cathode active material prepared above:

Get the synthetic LiNi _1/3 Mn _1/3 Co _1/3-1/20 Al _1/20 O ₂ g of the positive electrode active material in step (4), according to the positive electrode active material: acetylene black: the mass ratio of polyvinylidene fluoride is 84:8:8 Add acetylene black and polyvinylidene fluoride, then add N-methylpyrrolidone (NMP), mix well and make a slurry, coat it on the aluminum foil current collector, and dry it in a vacuum oven at 65°C After 24h, the positive electrode was assembled. The positive electrode, metal lithium sheet (negative electrode), Celgard separator and electrolyte (EC:DMC=1:1 1mol L ^-1 LiPF ₆ solution) were assembled into a button battery in a glove box.

Use the LAND CT2001A battery test system to measure the charge and discharge performance of the assembled button battery, test the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1 for the assembled button battery at 2.8-4.5V, 0.1C magnification Electrochemical performance of _/20 Al _1/20 O ₂ cathode active material. The first charge and discharge, cycle performance and coulombic efficiency curves of the prepared LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ cathode active material under the above test conditions are shown in Figure 3 and Figure 4 and Figure 5.

From Figure 3, Figure 4 and Figure 5, it can be seen that the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ cathode active material was first The charge and discharge capacities are 204.5mAh·g ¹ and 160.9mAh·g ¹ respectively, the initial discharge efficiency is 78.7%, and the irreversible capacity is 21.3%. After 20 charge and discharge cycles, the discharge capacity remains at 152.1mAh·g ¹ . The retention rate was 94.53% of the initial discharge capacity.

Example 2

Lithium cobalt oxide (LiCoO ₂ ), lithium nickel manganese oxide (LiNi _1/2 Mn _1/2 O ₂ ) and lithium nickel cobalt manganese oxide ( LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ) positive electrode waste 20g, wherein LiNi _1/3 Co _1/3 Mn _1/3 O ₂ is a material modified by Al ₂ O ₃ nanoparticles coating, using NMP dissolves the binder to separate the above-mentioned mixed positive electrode material, and synthesizes an aluminum-doped nickel-cobalt lithium manganate positive electrode active material according to the following steps, and the specific steps are as follows:

(1) The separated mixed positive electrode waste containing a small amount of Al ₂ O ₃ was placed in a constant temperature resistance furnace at 400°C for 8 hours to obtain the positive active material, and an infrared carbon-sulfur analyzer was used to detect that the mass fraction of carbon in the positive active material was lower than 0.001%, indicating that the positive electrode active material does not contain the conductive agent and the binder.

(2) The analysis method of the metal content in the positive electrode active material is the same as in Example 1, and the specific results are shown in Table 2.

Table 2 Mass content of metal in positive electrode active material

Metal Ni co mn Li Al Mass content (wt.%) 19.27 20.35 22.76 12.98 1.26

(3) According to the mass content of the metal in the positive electrode active material and the molecular formula of the aluminum-doped nickel-cobalt lithium manganate to be synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ in Ni , Mn, Co and Al atomic number ratio, with nickel oxide, cobalt tetraoxide, manganese dioxide or aluminum oxide so that the molar ratios of Ni and Mn, Ni and Co and Ni and Al are 1:1, 1.176:1 and 6.667:1, and then grind for 8h with a ball mill, so that the above mixture is fully ground and mixed uniformly to obtain the positive electrode active material precursor powder.

(4) add lithium acetate to the positive electrode active material precursor powder that step (3) obtains, make the ratio of the amount of substance of Li and the total amount of substance of Ni, Co, Mn and Al be 1.05～1.1, use After the ball mill is fully ground and mixed evenly, pass through a 800-mesh standard sieve, place the sieved material in a high-temperature furnace, heat up to 850°C at a rate of 5°C min ^-1 , and then roast it at a constant temperature in an oxygen atmosphere for 18 hours, then The temperature was lowered to 40°C at a rate of 3°C·min ^-1 to obtain an aluminum-doped nickel-cobalt lithium manganate cathode active material LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ .

The prepared LiNi _1/3 Mn _1/3 Co _1/3-1/20 Al _1/20 O ₂ was characterized by XRD and SEM using the method described in Example 1. The characterization results show that the LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ prepared in this example is a layered material with a pure phase, and there are no impurity peaks in the XRD spectrum; its morphology It is spherical, the primary particle size is 2μm-3μm, and the secondary particle is an aggregate of primary particles.

A button battery was assembled using the LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ cathode active material prepared above:

Get the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₃ g of positive electrode active material, according to the mass ratio of positive electrode active material: acetylene black: polyvinylidene fluoride is 80:15: 5. Add acetylene black and polyvinylidene fluoride. The positive electrode manufacturing method, button cell assembly method and electrochemical performance testing method are the same as in Example 1.

The electrochemical test results show that the first charge and discharge capacity of the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/20 Al _1/20 O ₂ positive electrode active material at 2.8-4.5V and 0.1C rate are respectively 211.9mAh·g ¹ and 172.2mAh·g ¹ , the first discharge efficiency is 81.3%, the irreversible capacity is 18.7%, after 20 charge-discharge cycles, the discharge capacity still remains at 164.7mAh·g ¹ , and the capacity retention rate is the initial discharge 95.64% of capacity.

Comparing Example 1 and Example 2 as can be seen:

The aluminum in Example 1 is mixed in during the separation process of the positive electrode material, and it still exists in the form of metal foil, so it needs to be fully ground to mix evenly, so as to ensure that these metals enter the crystal lattice of nickel cobalt lithium manganese oxide . The positive electrode material treated in Example 2 is a metal compound-coated and modified material, which exists in the form of compound powder. From the experimental results of Example 1 and Example 2, it can be seen that the material synthesized in Example 2 uses a metal compound coated modified material, and the prepared LiNi _1/3 Mn _1/3 Co _{1/3 –1/20} Al _1/20 O ₂ has better electrochemical performance.

Example 3

Take respectively 10 g of lithium cobalt oxide (LiCoO ₂ ) positive electrode waste and 20 g of lithium nickel manganese oxide (LiNi _1/2 Mn _1/2 O ₂ ) positive electrode waste separated from lithium-ion batteries, and use NMP to dissolve the binder to separate the above-mentioned Mix the positive electrode material in the positive electrode waste and mix evenly, which contains a small amount of fine copper foil fragments mixed in when the waste lithium ion battery is disassembled and separated. Follow the steps below to synthesize the copper-doped nickel-cobalt lithium manganate positive electrode active material. The specific steps are as follows :

(1) Put the separated mixed positive electrode waste containing a small amount of copper foil fragments in a muffle furnace at 1000°C for 2 hours to obtain the positive active material, and use an infrared carbon-sulfur analyzer to detect that the mass fraction of carbon in the positive active material is less than 0.001 %, indicating that the positive electrode material does not contain conductive agents and binders.

(2) The analysis method of the metal content in the positive electrode active material obtained in step (1) is the same as in Example 1, and the specific results are shown in Table 3.

Table 3 Mass content of metal in positive electrode active material

Metal Ni co mn Li Cu Mass content (wt.%) 23.72 19.55 21.04 10.57 1.34

(3) According to the mass content of the metal in the positive electrode active material and the molecular formula of the copper-doped nickel-cobalt lithium manganate to be synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/15 Cu _1/15 O ₂ Ni in , Mn, Co and Cu atomic number ratio, mix nickel acetate tetrahydrate, cobalt acetate tetrahydrate, manganese acetate tetrahydrate or copper nitrate so that the molar ratios of Ni and Mn, Ni and Co and Ni and Cu are respectively 1: 1. 1.25:1 and 5:1, and then use a ball mill to grind for 24 hours, so that the above mixture is fully ground and mixed uniformly to obtain a positive electrode active material precursor powder.

(4) add lithium oxalate and lithium acetate to the positive electrode active material precursor powder that step (3) obtains, make the ratio of the amount of substance of Li and the total amount of substance of Ni, Co, Mn and Al be 1.05～ 1.1, use a ball mill to fully grind and mix evenly, pass through a 1000-mesh standard sieve, place the sieved material in a high-temperature furnace, heat up to 800°C at a rate of 10°C·min ^-1 , and then roast at a constant temperature in an aerobic atmosphere 20h, and then slowly lowered to 60°C to obtain copper-doped nickel-cobalt lithium manganese oxide positive electrode active material LiNi _1/3 Mn _1/3 Co _1/3–1/15 Cu _1/15 O ₂ .

Using the method described in Example 1, the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/15 Cu _1/15 O ₂ was characterized by XRD and SEM. The characterization results are: the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/15 Cu _1/15 O ₂ is a pure-phase layered material, and no other diffraction peaks are detected in the XRD pattern; the morphology is Spherical, the primary particle size is 1μm–3μm, and the secondary particle is an aggregate of primary particles.

Utilize the LiNi _1/3 Mn _1/3 Co _1/3–1/15 Cu _1/15 O ₂ cathode active material obtained by the above method to assemble a button battery:

Take the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/15 Cu _1/15 O ₅ g of positive electrode active material, according to the mass ratio of positive electrode active material: acetylene black: polyvinylidene fluoride is 80:10: 10 was mixed with acetylene black and polyvinylidene fluoride, and the positive electrode manufacturing method, button battery assembly method and electrochemical performance testing method were the same as in Example 1.

The electrochemical test results show that the first charge and discharge capacity of the synthesized LiNi _1/3 Mn _1/3 Co _1/3–1/15 Cu _1/15 O ₂ positive electrode active material at 2.8-4.5V and 0.1C rate are respectively 202.9mAh·g ¹ and 158.7mAh·g ¹ , the initial discharge efficiency is 78.2%, and the irreversible capacity is 21.8%. After 20 charge-discharge cycles, the discharge capacity remains at 151.9mAh·g ¹ , and the capacity retention rate is the initial discharge 95.7% of capacity.

The applicant declares that the present invention illustrates the detailed methods of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed methods, that is, it does not mean that the present invention must rely on the above-mentioned detailed methods to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (10)

1. A method utilizing lithium-ion battery cathode waste to synthesize metal-doped nickel-cobalt lithium manganese oxide, characterized in that, said metal-doped nickel-cobalt lithium manganese oxide has the following composition: LiNi _x Mn _y Co _{1-x-y -z} M _z O ₂ , wherein M is any one or at least two of Cu, Al, Fe, Mg, Cr, Ti, Ce or Y, 0<x<1, 0<y<1, 0<z<0.1, and 0<x+y+z<1; The method comprises the steps of: (1) remove the binder and the conductive agent in the positive electrode waste of the lithium ion battery to obtain the positive electrode active material; (2) Determination of the elemental composition of the positive electrode active material; (3) According to the element composition of the positive electrode active material, adjust the content of one or at least two of Ni, Co, Mn or M in the positive electrode active material so that the molar ratio conforms to the molecular formula LiNi _x Mn _y Co _{1–x–y -zMzO2In} the _molar ratio of Ni, Co, _Mn and M, to obtain positive active material precursor powder; (4) Adding a lithium source to the positive electrode active material precursor powder, and using a high-temperature solid-state reaction to obtain metal-doped nickel-cobalt lithium manganese oxide. 2. The method according to claim 1, wherein the anode active material in step (1) is: nickel-based oxide, cobalt-based oxide, manganese-based oxide, M-doped nickel-based oxide , M-doped cobalt-based oxide, M-doped manganese-based oxide, M compound-coated modified nickel-based oxide, M compound-coated modified cobalt-based oxide, or M compound-coated modified Any one or a combination of at least two of the manganese-based oxides; Preferably, the M is derived from the impurity metal mixed in the process of separating the positive electrode waste of lithium-ion batteries to obtain the positive electrode active material or the metal introduced by the positive electrode active material due to doping or coating modification; Preferably, the M is derived from the metal introduced by the positive electrode active material due to doping or coating modification. 3. The method according to claim 1 or 2, characterized in that, the mass fraction of carbon in the positive electrode active material described in step (1) is lower than 0.001%; Preferably, step (1) obtains the positive electrode active material by roasting the lithium ion battery positive electrode waste; Preferably, the calcination temperature is 400-1000°C, preferably 500-800°C; Preferably, the roasting time is 2 to 8 hours, preferably 4 to 6 hours; Preferably, the calcination is carried out in a high temperature furnace. 4. The method according to any one of claims 1-3, characterized in that, step (2) adds the positive electrode active material to a strong acidic solution, heats and digests it, and then measures the elemental composition of the positive electrode active material; Preferably, the heating and digestion time is 1 to 6 hours; Preferably, step (2) uses ICP-OES to determine the elemental composition of the positive electrode active material. 5. The method according to any one of claims 1-4, characterized in that, step (3) adds any one or at least two of Ni source, Co source, Mn source or M source to the positive electrode active material. species to adjust the content of elements in the positive active material; Preferably, the source of Ni, Co, Mn or M is independently an oxide, chloride, sulfate, nitrate, acetate or oxalate of Ni, Co, Mn or M; Preferably, the cathode active material in step (3) is ground with the added Ni source, Co source, Mn source or M source to obtain a cathode active material precursor powder, and the grinding time is 8-24 hours. 6. according to the described method of one of claim 1-5, it is characterized in that, the lithium source described in step (4) is lithium carbonate, lithium chloride, lithium sulfate, lithium nitrate, lithium acetate or lithium oxalate any one or a mixture of at least two; Preferably, the lithium source added in step (4) makes the ratio of the amount of Li to the total amount of Ni, Co, Mn and M 1.05 to 1.1; Preferably, the temperature of the high-temperature solid-phase reaction in step (4) is 800-900° C., and the reaction time is 15-20 h; Preferably, the heating rate during the high temperature solid phase reaction in step (4) is 2-10°C·min ^-1 ; Preferably, the high-temperature solid-phase reaction described in step (4) is carried out in an oxygen atmosphere; Preferably, the high-temperature solid-state reaction in step (4) is as follows: after raising the temperature to 800-900°C at a rate of 2-10°C·min ^-1 , roasting at a constant temperature in an aerobic atmosphere for 15-20 hours, and then heating at a temperature of 1-5 The temperature is lowered at a rate of ℃·min ^-1 to 10-60 ℃ to obtain metal-doped nickel-cobalt lithium manganese oxide. 7. The method according to any one of claims 1-6, characterized in that, step (4) carries out high-temperature solid-state reaction after grinding and sieving the lithium source and positive electrode active material precursor powder; Preferably, the grinding is carried out on a ball mill; Preferably, the mesh size of the sieve is 200-1000 mesh. 8. The method according to any one of claims 1-7, characterized in that the method comprises the steps of: (1) placing the separated lithium-ion battery positive electrode waste material in a high-temperature furnace for roasting, removing the binder and conductive agent therein to obtain the positive electrode active material; (2) Determining the elemental composition of the positive active material; (3) According to the element composition of the positive electrode active material, adjust the content of Ni, Co, Mn or M in the positive electrode active material so that the molar ratio conforms to the molecular formula LiNi _x Mn _y Co _{1–x–y–z} M _z O ₂ In the molar ratio of Ni, Co, Mn and M, the positive electrode active material precursor powder is obtained; (4) Add a lithium source to the positive electrode active material precursor powder so that the molar ratio of Li to the sum of Ni, Co, Mn and M is 1.05 to 1.1, and then raise the temperature to 800 at a rate of 2 to 10°C·min ^-1 After ~900°C, it is roasted at a constant temperature in an oxygen atmosphere for 15-20 hours, and then slowly lowered to room temperature to obtain metal-doped nickel-cobalt lithium manganese oxide. 9. A metal-doped nickel-cobalt lithium manganese oxide prepared by the method according to any one of claims 1-8. 10. A use of the metal-doped nickel-cobalt lithium manganese oxide according to claim 9, which is used in the field of positive electrode materials for lithium-ion batteries.