Charge material synthesized from recycled lithium-ion batteries

Abstract

To provide an electric charge material synthesized from recycled lithium ion batteries.SOLUTION: Lithium-ion battery (LIB) recycling is considered as an important component to industry sustainability. A massive number of LIBs in portable electronics, electric vehicles and grid storage will eventually end up in wastes, leading to serious economic and environmental problems. Hence, tremendous effort has been made to improve hydrometallurgical recycling process since it is the most promising option for handling end-of-life LIBs owing to its wide applicability, low cost and high productivity. Despite these advantages, some extra elements (Al, Fe, C, F, etc.) remain as impurities in a removal process and remain in a solution, presenting a challenge to obtaining high quality cathode material. This approach demonstrates improved electrochemical performances by adding potential impurities in a leaching solution.SELECTED DRAWING: None

Description

[Technical Field]

[0001] Related applications This patent application relates to U.S. Patent Application Publication No. 15 / 358,862, filed on November 22, 2016, entitled "METHOD AND APPARATUS FOR RECYCLING LITHIUM-ION BATTERIES," now U.S. Patent No. 10,522,884, which is incorporated herein by reference in its entirety. [Background technology]

[0002] background Lithium-ion batteries (LIBs) are widely used in automotive, personal electronics, and industrial applications. The waste flow of batteries to be recycled generally requires the rough agitation (crushing and shredding) of complete battery assemblies, resulting in a mixture of cathode, anode, separator, and casing materials. The mainstream cathode materials used in LIBs (e.g., NCM) consist of heavy metals such as nickel and cobalt, which are not only toxic but also expensive and limited. Undoubtedly, the ever-growing burden of battery waste can become an environmental and economic challenge without a substantial solution for managing used LIBs. Recycling technologies mainly fall into three categories: dry smelting recycling, wet smelting recycling, and direct physical recycling. Wet smelting is widely adopted in both research and industry as a promising method for battery recycling due to its high recovery efficiency, large-scale production capacity, and low energy costs. [Overview of the project] [Problems that the invention aims to solve]

[0003] Lithium-ion battery (LIB) recycling is considered a crucial component of industrial sustainability. Large quantities of LIBs used in portable electronics, electric vehicles, and grid storage eventually become waste, leading to serious economic and environmental problems. Therefore, significant efforts are being made to improve the wet smelting recycling process, as it is the most promising option for processing used LIBs due to its broad applicability, low cost, and high productivity. Despite these advantages, foreign elements (such as Al, Fe, C, and F) often remain as impurities in the removal process and in the solution, posing challenges in obtaining high-quality cathode material. [Means for solving the problem]

[0004] overview The configurations described herein demonstrate the advantageous improvements resulting from fluorine impurities or doping in NCM cathode materials obtained by wet smelting coprecipitation. Fluorine impurities up to 5 at% increase the Ni content on the surface of the cathode particles. 2+ Due to the ratio, it can have a positive effect on the recovered material. Furthermore, the presence of fluoride ions in the coprecipitation forms holes in the cathode particles, dramatically improving rate capability and cycling properties. Compared to virgin charged material, NCM622(LiNi) with 0.2 at% fluorine impurities 0.6 Co 0.2 Mn 0.2 The capacity of the O2) material increased by approximately 8% (167.7 mAh / g) and exhibited a remarkable capacity retention rate of 98.0% after 100 cycles at 0.33C. Furthermore, the cathode material with 0.2 at% fluorine impurities showed significantly better rate performance than the virgin cathode material, particularly at high rates (an increase of approximately 7% at 5C). These results demonstrate improved electrochemical performance by adding potential impurities to the leaching solution, and more specifically, demonstrate that low concentrations of fluorine impurities are desirable in the wet smelting recycling process, especially for NCM formulations. The disclosed method demonstrates favorable implications in the design of high-performance NCM622 cathode materials by co-precipitation production via ion doping.

[0005] The configuration described herein is based in part on the observation that recirculation flows for lithium-ion batteries tend to introduce additional materials, often considered “impurities.” Physical removal of previously placed batteries introduces structural and circuit aspects, such as the physical casing, current collector, and internal circuitry, into the recirculation flow. Existing impurities may also be present in the depleted / used charge material. Unfortunately, conventional methods have the drawback of being difficult to completely remove impurities, often resulting in a trade-off where impurities are sufficiently removed without removing valuable charge material compounds. The configuration described herein substantially overcomes the shortcomings of conventional methods by identifying impurities that actually have a favorable effect on the performance of the resulting charge material.

[0006] Battery recycling methods identify small or trace amounts of compounds in the leachate resulting from the recirculation flow of disassembled batteries. Battery performance is based on the ability of charged materials to generate electron flow by transferring electrons between ions within the charged material. Active charged materials contain particles that solidify or aggregate together to form molecular crystal or network structures. In particular, the oxidation number of each molecule on the particle surface affects battery performance in terms of aspects such as charge capacity, discharge rate, and charge cycle life. The inclusion of certain additional trace elements, whether incidental inclusion from the recirculation flow or addition to the leachate, or through "doping," can have a favorable effect on the performance of the resulting recycled battery. In particular, small amounts of halides such as fluorine have the ability to promote the +2 oxidation number of nickel and cobalt. An increase of +2 atoms to atoms with a +3 oxidation number on the particle surface has a favorable effect on performance.

[0007] A high-efficiency closed-loop wet smelting recycling method for recycling used LIBs has been developed in the above-cited application. In this process, the used LIBs are disassembled, crushed, and sieved. The resulting mixed powder passes through leaching and subsequent purification processes. Then, the purified solution is adjusted to the desired concentration ratio of the target charge materials for subsequent coprecipitation to produce a precursor. The final recovered cathode material is obtained by high-temperature sintering of the precursor. This novel recycling method has a high recovery efficiency (about 90%), which is applicable to a wide range of cathode materials (LiNi x Co y Mn z O2, x + y + z = 1). In particular, the recovered cathode products have similar or even better electrochemical properties compared to commercial counterparts. However, impurities resulting from incomplete purification remain a potential problem of wet smelting technology. That is, due to their similar properties, it is difficult to separate all impurity elements such as Al, Fe, and Cu from the useful transition metals in the solution. The beneficial effects of impurities on the recovered cathodes have attracted even greater attention among researchers. For example, metal ions such as Al 3+ , Fe 3+ and Cu 2+ have been demonstrated to have a beneficial effect on the final recovered cathodes only when the impurity levels are very low. In particular, these cations can replace transition metal ions in the cathode crystal by forming precipitates during synthesis.

[0008] The disclosed method describes the improved performance of NCM, particularly NCM622 material, recovered by wet smelting synthesis under the influence of fluorine impurities. The disclosed method is also applicable to other NCM chemicals. An additional fluorine source NaF having contents of 0.2 at%, 1 at%, to 5 at% (relative atomic percent of all transition metals, Ni+Co+Mn=1) is added to the metal sulfate leaching solution before the coprecipitation reaction as an impurity required for the recycling process. Virgin NCM622 material (indicated as VNCM) and fluorine-impured material (indicated as 0.2FNCM, 1FNCM, and 5FNCM) are given. It has been shown that fluoride ions in coprecipitation generate holes in the precursor particles. After sintering, the fluoride ions occupy oxygen sites in the cathode crystal and Ni on the particle surface. 2+ / Ni 3+ It is known that it mainly forms bonds with Ni ions (NiF2), which significantly increases the ratio of fluorine impurities. When the level of fluorine impurities is not excessive, the bulk diffusivity is also improved due to small lattice expansion and an ordered structure. Both the 0.2FNCM and 1FNCM samples exhibited an excellent discharge capacity of approximately 167 mAh / g (about 8% better than VNCM) with an excellent capacity retention rate of approximately 98% (VNCM 94.8%) after 100 cycles at 0.33C. Furthermore, compared to virgin base materials, all FNCM cathodes have excellent rate capabilities, especially at high rates. Indeed, holes in the cathode particles and high surface Ni 2+ The content and improved lithium bulk diffusion rate demonstrate the positive aspects of fluorine impurities in wet smelting recycling. Furthermore, when excessive amounts of fluoride are introduced into the NCM622 crystal lattice, the oxidation state of cobalt on the cathode surface is affected. 2+The concentration detected on the 5FNCM cathode surface results in insufficient cation arrangement and structural stability, which are inferior to other F-doped NCM622 in terms of electrochemical properties. The results indicate that residual fluorine impurities have a favorable effect in the wet smelting recycling of batteries, but this is hindered at high levels of fluoride ion content (>1 at%). Furthermore, the disclosed method demonstrates the feasibility of mass production of "enhanced" NCM622 cathodes using a wet smelting method utilizing fluoride additives.

[0009] A disclosed method for producing a charge material precursor having a preferred oxidation state for a secondary battery charge material in a particular configuration comprises forming a leaching solution containing the target charge material by leaching the target charge material obtained from a recirculating flow into a leaching solution, and controlling the pH of the leaching solution to dissolve the target charge material in the leaching solution. Particularly attractive battery chemicals include nickel, manganese, and cobalt charge materials (NMC or NCM). The method establishes a predetermined percentage of halides, such as fluorine, in the leaching solution based on one or more oxidation states of the target charge material, such as the ratio of +2 to +3 oxidation states resulting from the doped material. The recycled material is obtained by adding a strong base to the leaching solution to precipitate the charge material particles. The charge material particles contain the target charge material in the form of a charge material precursor for subsequent sintering with a Li compound.

[0010] Brief explanation of the drawing The aforementioned and other features are evident from the following description of the specific embodiments disclosed herein, as illustrated in the accompanying drawings, where the same reference numerals refer to the same parts throughout different drawings. The drawings are not necessarily to scale and are rather focused on illustrating the principles of the invention. [Brief explanation of the drawing]

[0011] [Figure 1] This is a contextual diagram of a wet smelting and recycling method suitable for use with the configuration described herein. [Figure 2] The precursor morphology shows increases in average particle size and sphericity at different time points. [Figure 3] The image shows an SEM image of a NCM622 sample synthesized from a precursor. [Figure 4A] This demonstrates that the phase and structure of the prepared material can be analyzed in pattern by powder X-ray diffraction. [Figure 4B] This demonstrates that the phase and structure of the prepared material can be analyzed in pattern by powder X-ray diffraction. [Figure 4C] This demonstrates that the phase and structure of the prepared material can be analyzed in pattern by powder X-ray diffraction. [Figure 4D] This demonstrates that the phase and structure of the prepared material can be analyzed in pattern by powder X-ray diffraction. [Figure 5A] The purification profiles of the VNCM cathodes of the materials shown in Figures 4A to 4D are displayed. [Figure 5B] The purification profiles of the 0.2FNCM cathodes of the materials shown in Figures 4A to 4D are displayed. [Figure 5C] The purification profiles of the 1FNCM cathodes of the materials shown in Figures 4A to 4D are displayed. [Figure 5D] The purification profiles of the 5FNCM cathodes of the materials shown in Figures 4A to 4D are displayed. [Figure 6A] The spectrum of the surface scan of the cathode material is shown. [Figure 6B] The spectrum of the surface scan of the cathode material is shown. [Figure 6C] The spectrum of the surface scan of the cathode material is shown. [Figure 7A] This shows the inverse convolution scanning of Ni surface ions on cathode material particles. [Figure 7B] This shows the inverse convolution scanning of Co surface ions on cathode material particles. [Figure 7C] This shows the percentage of Ni surface ions on the cathode material particles. [Figure 7D] This shows the percentage of Co surface ions on the cathode material particles. [Figure 8A]The plot shows the fitting line between peak current (Ip2) and scan speed (ν). [Figure 8B] The plot shows the fitting line between peak current (Ip2) and scan speed (ν). [Figure 8C] The plot shows the fitting line between peak current (Ip2) and scan speed (ν). [Figure 9] This shows Li ion diffusion in different cathode crystal structures. [Figure 10A] This is a schematic diagram showing holes formed due to doping / impurities. [Figure 10B] This is a schematic diagram showing holes formed due to doping / impurities. [Figure 10C] This is a schematic diagram showing holes formed due to doping / impurities. [Modes for carrying out the invention]

[0012] Detailed explanation Examples, methods, and apparatus for recycling batteries such as lithium-ion batteries are described below. The proposed methods are illustrative and applicable to other lithium and non-lithium batteries for recycling used batteries to recover cathode active material suitable for use in new batteries.

[0013] Figure 1 is a contextual diagram of a wet smelting and recycling method suitable for use with the configurations described herein. Cathode materials widely used in commercial lithium-ion batteries include LiCoO2, LiMn2O4, LiNiO2, and LiNi x Co y Al z O2, LiLiLi x Mn y Co zThis includes O2 and LiFePO4. To effectively recycle lithium-ion batteries, it is advantageous to consider all the various battery chemicals. Therefore, it is advantageous to develop simpler and environmentally acceptable recycling methods that are generally applicable to a wide range of LIBs. The configurations disclosed herein illustrate examples of producing active materials for batteries using recycled materials by extracting compounds containing desirable elements of Co, Ni, Mn, and Li from a mixed cathode material. Other chemicals can be recycled using the disclosed method.

[0014] Referring to Figure 1, in step 1, the discharged Li-ion battery is crushed / shredded. As shown in step 1a, a mechanical separation process is applied as a pretreatment to separate the outer casing and case and plastic fragments. The recirculated flow is a mixed mass containing at least a portion of the charged material, e.g., Ni, Mn, and Co of the target charged material, and represents the battery chemicals and ratios of the intended recycled battery, e.g., NMC622, NMC532, NMC111, or NMC811.

[0015] As shown in step 2, the sieved cathode powder is leached at 70-80 degrees Celsius for about 2-3 hours with a reducing agent such as 4-5 M sulfuric acid (H2SO4) and 29-32% hydrogen peroxide. Other concentrations of leaching acids and other reducing agents can also be used. In another form, a leaching solution can be formed from leaching acids containing one or more of the following: sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, boric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, and perchloric acid. By adding hydrogen peroxide (H2O2), not only is Fe2+ converted to Fe3+, but other metal ions Mn, Ni, and Co are also converted to 2+, thus yielding separated iron by controlling the pH of the solution in step 3. As shown in step 2a, after filtration, residual LiFeO4 and carbon can be separated by centrifugation. As shown in step 2b, other impurities are also removed from the surface of the solution.

[0016] As shown in step 3, when the crushed cathode raw materials form granular aggregates used to produce a solution of condensed battery material from spent cells, the target metal elements are transferred to the aqueous solution. This includes target charge materials such as Co (cobalt), Ni (nickel), and Mn (manganese). Other target charge materials can be used with this method along with other battery chemicals. Iron, copper, and aluminum are extracted as Fe(OH)3, Cu(OH)2, and Al(OH)3 by adjusting the pH. This requires adjusting the pH to a range of 3.0 to 7.0. Therefore, by adding NaOH solution to adjust the pH, Fe(OH)3, Cu(OH)2, and Al(OH)3 with lower solubility coefficients are deposited, and Mn is added to the solution. 2+ Co 2+ Ni 2+ Maintain, then Fe(OH) 3、 Cu(OH)2 and Al(OH)3 are separated by filtration. The above process involves maintaining the solution at a temperature of 40°C to 80°C, and care must be taken to avoid the high heat required in conventional methods.

[0017] pH adjustment for impurity removal generally involves adjusting the pH based on the specific impurities to be removed. A pH range of approximately 3–5 is suitable for precipitating iron from the solution, for example. Copper tends to precipitate at a pH of around 5–7. Depending on the amount and type of impurities in the recirculated flow, the impurity removal stage can target different pH ranges. When charged material metals (Ni, Mn, Co) are dissolved, the pH will likely be reduced to around 1–3 depending on the amount and concentration of acid leaching. Before raising the pH to precipitate the high-purity form of NCM, impurities can be precipitated by optionally adding reducing agents, which are further discussed below. In other words, while raising the pH by adding sodium hydroxide or other strong bases, impurities precipitate at a lower pH, and then the NCM hydroxide precipitates at a higher pH. The strong bases may also include precipitating agents such as a mixture of sodium hydroxide or potassium hydroxide.

[0018] Next, the target charge material is dissolved in the solution. Based on a predetermined target ratio of the target charge material, the solution is adjusted to achieve the predetermined ratio of the target charge material. In the method of the example, this is a 6:2:2 combination of nickel, cobalt, and manganese, but any suitable ratio can be used. Thus, adjusting the solution involves identifying the desired ratio of charge material for use in the recycled cathode material obtained from the resulting solution, and adding virgin material to achieve the desired ratio. Adding raw materials involves adding additional amounts of target charge material to achieve the desired ratio without separating the individual target charge material already in solution form, and thus the mixed target charge material (Co, Mn, Ni) does not need to be drawn or extracted separately as in conventional methods, which usually require high heat to break the molecular bonds of the compound.

[0019] In other words, the pH is first raised to extract elements considered to be "impurities," meaning anything other than the charge material. In NCM chemicals, this includes Fe, Cu, Al, and other trace materials. That is, Al is part of the battery chemicals in other battery formulations. Once the impurities are extracted, the pH is further raised to precipitate the target charge material. In the configurations described herein, halides such as fluorine are formed either from residual amounts from the recirculated flow and / or by the addition of additional materials as doping agents.

[0020] To achieve the desired chemical or target charge ratio of materials, Mn in solution 2+ Co 2+ Ni 2+ The concentrations were tested and their ratios were adjusted to 6:2:2 or to other suitable ratios using additional CoSO4, NiSO4, and MnSO4. NaOH solution was added to increase the pH to approximately 11, usually within the range of 10.0–13, thus adjusting the pH of the solution so that the target charge material for the new (recycled) charge material precipitated. As shown in step 4, Ni was added so that the molar ratio of each was 1:1:1. 1 / 3 Mn 1 / 3 Co 1 / 3 (OH)2 or Ni1 / 3 Mn 1 / 3 Co 1 / 3 O(OH) or mixtures thereof may co-precipitate. x Mn y Co z (OH)2 or Ni x Mn y Co z O(OH) or mixtures having different ratios of x, y, and z may also precipitate. As shown in step 5, Na2CO3 is added to the solution to deposit Li2CO3. Finally, the recovered Ni 1 / 3 Mn 1 / 3 Co 1 / 3 Cathode material is manufactured by sintering (OH)2 and Li2CO3.

[0021] In the embodiment, the target charge material includes manganese (Mn), cobalt (Co), and nickel (Ni) extracted from the charge material of a used battery cell, where the target charge material remains mixed in the solution while precipitation occurs. Adjusting the pH involves raising the pH by adding a substance such as NaOH (sodium hydroxide, also called caustic alkali solution or caustic soda) to allow the target charge material to precipitate, however any suitable substance for raising the pH can be used. As a final result, adjusting the pH involves raising the pH by adding sodium hydroxide to allow the precipitation of the target charge material without separately precipitating the individual compounds that define the target charge material, and using it as a cathode precursor material. The intermediate or precursor form yields the lithium oxide form after sintering with lithium carbonate Li2CO3.

[0022] Na2CO3 is added to the solution and Li2CO3 is deposited at approximately 40°C. As shown in steps 5 and 5a, after filtration, Li2CO3 is recycled as a starting material to produce the cathode active material LiNi 1 / 3 Mn 1 / 3 Co 1 / 3O2 can be synthesized. Therefore, this method involves returning lithium to the precipitated target charge material to form a cathode active material suitable for a new battery, and precipitating the target charge material in a predetermined ratio to form a charge material for a new battery.

[0023] As shown in step 6, the co-precipitated material Ni 1 / 3 Mn 1 / 3 Co 1 / 3 (OH)2 or Ni 1 / 3 Mn 1 / 3 Co 1 / 3 O(OH) or mixtures thereof and recovered Li2CO3 are used in a Li-to-M ratio (M=Ni 1 / 3 Mn 1 / 3 Co 1 / 3 The mixture was mixed with additional Li2CO3 at a molar ratio of 1.1 and finely ground in a mortar. The mixture can be reformulated by any suitable processing to form the cathode active material 134 for the new battery 140. In the method of the example, the mixture was sintered at 900°C for 15 hours. The reaction product can be finely ground into a powder and then dispersed and reformed into the new cell 140. LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2 is sintered at 900°C for 15 hours using a high-temperature solid-state method.

[0024] Expanding on the method in Figure 1, the cathode material is synthesized by a coprecipitation reaction and post-sintering method, where the transition metal ion M is ionized. 2+ (M=Ni, Co, Mn) co-precipitates in alkaline solution, and Ni 0.6 Co 0.2 Mn 0.2 A (OH)2 precursor is formed, and then the mixture of the dried precursor and lithium salt is sintered to form the final cathode sample, LiNi 0.6 Co 0.2 Mn 0.2O2(NCM622) was obtained. The following examples describe a leaching solution containing a target charge material yielding a 622NMC charge material precursor, wherein the halide consists of a predetermined percentage of fluoride, substantially about 1.0 at%. Yet another configuration may establish a predetermined percentage of halides in the leaching solution based on one or more oxidation states of the target charge material intended to form on the obtained charge material particles. Halides are based on the electronegativity of a halogen and another atom. Other suitable halides can be used, including some more common ions: chloride (Cl-), bromide (Br-), iodide (I-), and astatinide (At-).

[0025] Metal sulfate hydrates NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O were added to deionized (DI) water in a stoichiometric ratio of 6:2:2 to obtain 2M metal sulfate solutions. To prepare samples containing impurities, NaF salts were mixed into the metal sulfate solutions at different concentrations of 0.2 at%, 1 at%, and 5 at%, and are referred to below as 0.2FNCM, 1FNCM, and 5FNCM, respectively. Before initiation, 0.5M NH3·H2O was added to a 5L continuous stirring tank reactor (CSTR) as a complexing agent. The metal sulfate solutions and ammonia solutions were then pumped into the reactor at a controlled flow rate. Meanwhile, a 7.5M NaOH solution was added to the reactor by a peristaltic pump to maintain the reaction under the desired pH conditions. The coprecipitation reaction was carried out continuously for 12 hours under nitrogen protection at constant conditions of pH=11 and T=55. After the reaction, the synthesized precursor was filtered and washed with DI water to remove residue until the pH dropped to 7, and then the precursor powder was dried overnight in an oven at 130°C. To obtain the cathode material, the precursor was mixed with Li2CO3 in a mortar at a stoichiometric ratio of 1:1.05 (5% excess lithium salt was used to compensate for the decrease in lithium ions during sintering). The mixture then underwent a two-step sintering method: (I) heated to 450°C for 5 hours, then cooled to room temperature, and (II) heated to 850°C for 18 hours, then the same cooling method was followed (the gradient rate was fixed at 2°C / min). Finally, a total of four cathode materials were obtained: LiNi 0.6Co 0.2 Mn 0.2 O2(VNCM) and LiNi 0.6 Co 0.2 Mn 0.2 F x O 2-x (x = 0.002, 0.01, and 0.05 are called 0.2FNCM, 1FNCM, and 5FNCM, respectively).

[0026] The morphology and microstructure of the particles were observed using a scanning electron microscope (SEM, JEOLJSM-7000F) coupled with energy-dispersive spectroscopy (EDS), and the elemental composition was analyzed. The precise concentrations of all metallic elements in the cathode were measured using inductively coupled plasma mass spectrometry (ICP-MS). The phases of each sample were identified by powder X-ray diffraction (XRD, PANalytical Empyrean) with Cu Kα (λ=1.54 Å) and a step size of 0.02° / scan. To obtain lattice parameters, the following Rietveld analysis was performed using FullProf software, and LiNi 0.6 Co 0.2 Mn 0.2 The powder structure of O2 (PDF#00-066-0854) was selected as the reference model. X-ray photoelectron spectroscopy (XPS) data were obtained from all cathodes using a PHI 5000 VersaProbe II instrument (Physical Electronics) to investigate the elemental composition and oxidation states of transition metals. + An X-ray source with a monochromatic AlKα (hυ=1486.6eV) set to ion and electron beam sample neutralization and fixed analyzer transmission mode was operating at 25W. The XPS spectrum was calibrated to CC at 284.8eV before subsequent deconvolution simulations (fitting the spectrum to multiple Gauss-Lorentz peaks) were processed on XPSpeak software.

[0027] CR-2032 coin cells, consisting of a cathode electrode, separator, electrolyte, and lithium metal anode, were assembled in an argon gas-filled glove box (H2O, O2 < 1 ppm) and their electrochemical performance was investigated. To prepare the electrodes, an active material (cathode powder, 80 wt%), conductive carbon (C65, 10 wt%), and polyvinylidene fluoride binder (PVDF, 10 wt%) were mixed in N-methyl-2-pyrrolidone (NMP) solvent to form a slurry. Next, the mixed slurry was cast onto aluminum foil using a doctor blade (MTI) and dried overnight at 60°C. Circular electrodes (Φ=12 mm) were calendered and punched out from the dried electrode sheet, with a density of approximately 3.5 to 4.0 mg / cm². 2 A final thickness of approximately 40 μm with an active mass loading was obtained. The electrode sample was further dried overnight in a vacuum furnace at 120°C to remove residual NMP and moisture. A three-layer polypropylene-polyethylene-polypropylene film (Φ=16 mm) and 1 M LiPF6 in ethylene carbonate / ethyl methyl carbonate (EC / EMC, 3:7 wt%) were used as the separator and electrolyte, respectively. The electrochemical performance was (Li / Li + The batteries were tested on a Land battery test apparatus (Land, CT2001A) at 3.0V to 4.3V. Specifically, the cells were measured at current densities of 0.33C and 5C in cycle tests, and the current density was set from 0.1C to 5C in rate performance tests (1C = 175mAh / g). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests were performed on an electrochemical analyzer (Bio-Logic SAS, VMP3) using the EC-Lab program. In the CV test, the scanning potential was set at a rate of 0.1mV / s (Li / Li + The voltage was set to 3.0V to 4.5V. In the EIS test, the cells before and after the cycle were measured with an amplitude of 10mV within the frequency range of 100kHz to 10mHz.

[0028] To monitor the morphology of the hydroxide precursor during synthesis, samples were collected every 3 hours and then analyzed by SEM. Figure 2 shows the precursor morphology at different time points, where average particle size and sphericity increase with increasing reaction time. At each specified time point, no clear differences were observed between samples from 0.2 FNCM (row 201), 1 FNCM (row 202), and 5 FNCM (row 203), indicating that the presence of fluoride ions in the alkaline environment during coprecipitation inhibits particle growth and prevents the formation of excess precipitate that hinders particle sphericity. Particle morphology is closely correlated with its physical properties, such as powder tap density. In Table I, the tap density also increases as the reaction progresses, and all FNCM samples share similar density levels at their respective time cross-sections. Compared to FNCM, the virgin group exhibits significantly lower powder tap densities at 3 hours (column 211), 6 hours (212), and 9 hours (213), representing approximately 77%, 79%, and 89% of the average precursors affected by fluorine impurities, respectively. However, when the precipitation process is completed at 12 hours (214), all samples approach similar density levels (approximately 1.90 g / ml). This phenomenon suggests that while fluorine impurities influence the co-precipitation process due to increased powder tap density caused by faster nucleation and particle growth in its initial stages, they do not result in significant changes in particle morphology and tap density once the reaction reaches a steady state.

[0029] [Table 1]

[0030] Figure 3 shows SEM images of NCM622 samples synthesized from precursors. In Figure 3, SEM images of 0.2FNCM (row 301), 1FNCM (row 302), and 5FNCM (row 303) are shown for the precursor (column 211), cathode (column 312), and cathode cross-section (column 313) (scale bar 10 μm). (Inset: higher magnification image with scale bar 2 μm). Typical nearly spherical secondary particles, composed of numerous extremely small flake-like primary particles, are observed in column 311. Primary particles are the most basic building blocks of the synthetic material. During the reaction, the growth, adhesion, and coagulation of primary particles produce spherical secondary particles. For all cathodes shown in column 312, the shape of the primary particles changes from flake to polygonal after precursor sintering at high temperatures. Both the precursor and cathode have uniform surface morphology and secondary particle size (approximately 8 μm), meaning that fluorine impurities have only a minimal effect on the morphology of the final cathode. However, the interior of the particles is quite different. As shown in the cross-sectional image given in column 313, holes are found within the FNCM cathode particles (indicated by circles and yellow arrows). Increasing the impurity concentration from 0.2 at% to 5 at% also results in hole formation within the cathode particles. This demonstrates that fluorine impurities are the fundamental cause of hole formation within cathode particles, and this favorable feature can lead to improved electrochemical performance.

[0031] The results of SEM-EDS mapping of the as-prepared cathode show that the transition metal elements Ni, Co, and Mn are homogeneously dispersed throughout the particles. The composition of each element in the NCM622 cathode at different impurity levels is measured by ICP-MS. As shown in Table II, the atomic ratios of Ni, Co, and Mn in all samples remain close to the theoretical values (6:2:2). Specifically, when calculating the exact atomic ratios in NCM for VNCM, 0.2FNCM, 1FNCM, and 5FNCM, they are 6:2.05:2.00, 6:2.11:2.01, 6:2.10:2.00, and 6:2.15:2.05 (Ni = 6), respectively. Furthermore, the lithium composition remains stable regardless of the change in the impurity concentration. Therefore, it can be concluded that fluoride ions do not occupy the cation sites during the synthesis process but replace oxygen in the cathode crystal.

[0032]

Table II

[0033] A typical mechanism for the synthesis of high-density and spherical hydroxide particles by coprecipitation can be implemented. There are two steps to form the precipitate: the transition metal ions are first coordinated by an ammonia complexing agent (1), and then slowly precipitate from the base solution (2). The related two-step reaction is as follows. M 2+ + nNH3 → [M(NH3) n 2+ (1) [M(NH3) n 2+ + 2OH - → M(OH)2↓ + nNH3 (2) In the initial stage, relatively sufficient fluoride ions can bring about the reaction: [M(NH3) n 2+ + 2F - → MF2 + nNH3 (3) This is the complex ion [M(NH3) n 2+ ​​​​It is consumed, and the equilibrium of reaction (2) is pushed to the left. In this case, the dissolution rate of the primary particles exceeds the recrystallization, and as a result, holes are generated in the precursor.

[0034] Figures 4A to 4D show the phases and structures of the prepared materials analyzed by powder X-ray diffraction with patterns. Figures 4A to 4D show the X-ray diffraction patterns of the precursor by magnification of the (001) plane in Figures 4A and 4B and the X-ray diffraction patterns of the cathode by magnification of the (003) plane in Figures 4C and 4D. Figures 5A to 5D show the purification profiles of VNCM, 0.2FNCM, 1FNCM, and 5FNCM cathodes. All the patterns in Figures 4A to 4B have the same diffraction peaks corresponding to β-Ni(OH)2, which is a layered metal hydroxide (PDF#00-059-0462). There are nine prominent diffraction peaks in the XRD spectra of all cathodes in Figures 4C to 4D that perfectly match LiNi 0.6 Co 0.2 Mn 0.2 O2 (PDF#00-066-0854). No extra phases or structural changes are found in the patterns of both the precursor and the cathode. Meanwhile, a high-purity phase and a sufficiently layered cathode material are maintained. Nevertheless, the (001) peak of the FNCM precursor spreads slightly as shown in 4A due to the decrease in the primary particle size. The (003) plane also shifts slightly to a lower angle for all FNCM cathodes as a result of the expansion of the c-axis of the crystal lattice (Figures 4C to 4D). It is noteworthy that 5FNCM has the lowest I (003) / I (104) ratio (1.59), while the other cathodes VNCM (1.81), 0.2FNCM (1.80), and 1FNCM (1.76) retain higher values. The higher I (003) / I (104) value indicates a lower Li + / Ni 2+ in the cathode material, mixing, which leads to excellent electrochemical performance. Therefore, the recovered cathodes under the influence of high-concentration fluorine impurities (5 at%) have no possibility of being competitive compared to others.

[0035] To obtain more detailed lattice information of the recovered cathode, structural parameters were calculated using Rietveld analysis, and the space group was formed.

number

[0036] [Table 3]

[0037] Figures 6A-6C show the spectra of surface scans of the cathode materials. XPS testing was used to investigate the composition and elemental valence states of the prepared cathode materials. The Na 1s survey scan in Figure 6A shows no signal in any of the samples. This confirms that Na-related substances are not present in the final recovered material. Figures 6B and 6C show the F 1s spectra of the surface and bulk of all cathode samples. A strong peak is observed in the surface spectrum of the FNCM cathode. In contrast, in Figure 6C, there is no fluorine signal at all. This means that fluoride ions mainly accumulate on the surface of the cathode particles rather than inside them. Furthermore, the peak in Figure 6B (approximately 685 eV) closely matches metallic fluorides such as LiF and TMF2 (TM=Ni, Co, or Mn). Additionally, the peak intensity relatively increases as the impurity concentration increases from 0.2 at% to 5 at%. Therefore, XPS analysis verifies the presence of fluoride in the cathode material by replacing oxygen, and more importantly, the fluoride ions are generally present near the particle surface, forming a layer with high levels of low-valence (+2)™ ions.

[0038] In the method of the claims, a predetermined percentage of fluoride is introduced into the leaching solution by adding fluorine or simply by residual amount before the precipitation of the charged material. The result is that each Ni on the surface of the charged material after subsequent sintering 3+ Ions and Co 3+ Ni exceeds ions 2+ Ions and / or Co 2+This is an increase in ions. Other ions can also achieve a favorable surface distribution based on the particle crystal structure.

[0039] Figures 7A-7D show the inverse convolution scan and percentages of Ni and Co surface ions on cathode material particles. Ni in the cathode material 2+ / Ni 3+ and Co 2+ / Co 3+ To clearly determine the relevant content, 2p 3 / 2 The exact percentage ratios of different TM ions are calculated by performing deconvolution of the peak region spectrum. Ni2p shown in Figure 7A 3 / 2 The fitted spectrum is Ni in the cathode. 2+ and Ni 3+ This shows a mixture. In the example, the leaching solution has fluoride in the range of 0.2 to 5 at% before precipitation of the charged material, and Ni on the surface of the charged material particles. 2+ The percentage of ions is increased to 40.1% to 43.8%. Therefore, fluorine is present on the particle surface of Ni and Co(Ni) having an oxidation state of 2+. 2+ Co 2+ ) has a quantifiable effect on increasing ). As demonstrated above, the leaching solution has fluoride in the range of 0.2-5 at% before precipitation of the charged material, and Ni on the surface of the charged material particles. 2+ This is the case when the percentage of ions is increased to 40.1% to 43.8%. Similarly, the leaching solution has fluoride in the range of 0.2 to 5 at% before the precipitation of the charged material, and Co on the surface of the charged material particles. 2+ This is the case where the percentage of ions is increased from 13.0% to 35.2%. Other ions can also be preferably dispersed based on halide doping. As shown above, Ni2p 3 / 2 The peak is Ni 2+ (854.7eV) and Ni 3+ It can be decomposed into (856.5 eV). Similarly, as shown in Figure 7B, Co2p 3 / 2 The peak is Co 2+ (782.1eV) and Co 3+It can be divided into (780.2 eV) portions. According to Figure 7C, Ni on the particle surface 2+ The ratio increased by approximately 4% for all FNCM cathodes, from 40.1% (VNCM) to an average of 43.8%. In contrast, Ni in the core 2+ The content is hardly affected by the additional fluorine impurities, and the maximum ratio change between VNCM and 5FNCM is less than 1%. This is because more Ni 2+ Further supporting the presence of ions near the surface of the FNCM cathode, which may contribute to a higher reversible capacity during repeated cycles. Figure 7D shows a very small amount of Co 2+ This indicates that it is on the virgin cathode surface. 2+ The percentage increases to approximately 13% for 0.2FNCM and 1FNCM, and reaches 35.2% for 5FNCM. In particular, when high levels of fluoride are introduced into the cathode particles (5 at%), it can be inferred that reduction of cobalt ions also occurs on the particle surface. Li + and Co 3+ It should be noted that the larger size and charge difference between them ensures sufficient cation arrangement, which is important for rapid lithium ion diffusion in the cathode. Therefore, significantly low surface Co 3+ Depending on the concentration, it is not surprising that 5FNCM has insufficient cation mixing, as previously revealed by XRD analysis. 2+ This ratio indicates that stability (approximately 36%) is maintained for all samples in bulk particle form.

[0040] Figures 8A-8C show (8A) plots of the fitting lines between peak current (Ip2) and scanning speed (ν) for the anode and cathode CV curves, and (8B) plots of the fitted lines for the cathode and (8C) plots of the calculated Li ion diffusion coefficient. Figure 9 shows Li ion diffusion in different cathode crystal structures. Referring to Figures 8A-9, the Randles-Sevcik equation was used with a series of cyclic voltammetry (CV) tests at various scanning speeds:

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[0041] According to the gradient, 0.2FNCM and 1FNCM are D compared to the virgin standard. Li It has a larger value, while the Li ion diffusion conditions at 5FNCM are the worst of all. In particular, at 0.2FNCM, the maximum Li diffusion coefficient is about 30% and 14% larger than the Li diffusion coefficient of the virgin standard, 2.04 × 10⁻⁶. -10 cm 2 / s (anode) and 4.83 × 10 -11 cm 2The value is / s (cathode), indicating that 0.2FNCM may have the best electrochemical performance among all prepared samples. The lattice image in Figure 9 demonstrates the effect on ion diffusion by including different levels of fluoride in the NCM crystal. It should be noted that the octahedral regions between the closely packed oxygen ions (marked with red x) are for Li ion diffusion in the layer. When small fluoride substitution occurs (<1 at%), the diffusion pathway remains possible. Since fluoride ions have a smaller ionic radius (approximately 1.3 Å) and charge number compared to oxygen ions (approximately 1.4 Å), such substitution can result in expanded spacing and reduced energy barriers, which cause an increase in Li ion diffusivity. However, excessive fluoride content (>5 at%) causes a considerable decrease in cation arrangement. Thus, more diffusion pathways result in mismatched Ni, which leads to reduced diffusion efficiency. 2+ It is blocked by ions.

[0042] Figures 10A-10C are schematic diagrams illustrating holes formed based on doping / impurity to illustrate the positive effect on the recovered NCM622 cathode caused by fluorine impurities. Adding small amounts of halides, such as fluorides, introduces holes into the precipitated charged material particles. The internal particle charge and force associated with these holes increase the 2+ to 3+ oxidation number ratio of the charged material precursor. By introducing a fluorine reaction equilibrium during coprecipitation, fluoride ions promote the dissolution of primary particles, forming cavities or holes in the precursor.

[0043] Figure 10A illustrates that the conventional virgin material shows solid particles 101 that do not contain holes. Figure 10B shows Ni containing holes 102. 2+ Negative F bonded to an ion 1- Figure 10C shows a fluorine content of approximately 1% with ions, and similarly surrounds hole 103, with 5% F. 1- This shows the increased density of ions.

[0044] Therefore, after the precursor is sintered, cathode particles having a hollow structure defined by holes are obtained in the FNCM material. Since the presence of holes can improve particle stability by reducing the total distance of Li diffusion and suppressing volume changes during repeated cycles, the definition of the particle structure containing holes has a positive effect on the rate performance and cycle stability of the cathode. Furthermore, for charge compensation, Ni is used in the FNCM cathode. 2+ A surface layer with an increased ratio of has been demonstrated, which substantially increases the reversible capacity of the material. High-valence Ni near the surface 3+ Reducing the amount of fluorine enhances the ability to maintain surface stability. Furthermore, when a very small portion of the lattice oxygen is replaced by fluoride ions, the Li diffusion coefficient is improved in FNCM cathodes (<1 at%), resulting in better structural and energy levels for ion transport in the lithium layer. Despite all their positive roles, undesirable high levels of cationic disorder are found in 5FNCM cathodes, which then have an undesirable effect on Li diffusion. Moderate levels of fluorine impurities or doping on recovered NCM622 cathodes obtained by wet smelting are advantageous. Similar advantages apply to at least other NMC chemicals. In general, these results support the advantages of fluorine impurities on NMC622 cathode materials.

[0045] Although the apparatus and methods specified herein have been shown and described in particular with reference to their embodiments, it will be understood by those skilled in the art that various modifications thereto in form and detail can be made thereto without departing from the scope of the invention as encompassed by the appended claims. [Explanation of Symbols]

[0046] 1 process 1a Process 2 steps 2a process 2b process 3 steps 3a Process 4 steps 4a Process 5 steps 5a Process 6 steps 101 Solid particles 102 holes 103 holes 134 Cathode Active Material 140 batteries 201 Row 202 Row 203 Row 211 columns 212 columns 213 columns 301 Row 302 Row 303 Row 311 columns 312 columns 313 columns

Claims

1. 1. A method for producing a charge material precursor having a preferred oxidation number for a secondary battery charge material, comprising: leaching a target charge material from the recycle stream into a leach solution to form a leach solution containing the target charge material; controlling the pH of the leaching solution to dissolve the target charge material in the leaching solution; establishing a predetermined percentage of halide in the leach solution; adding a strong base to the leaching solution to precipitate charge material particles, the charge material particles comprising the target charge material in the form of a charge material precursor for subsequent sintering with a Li compound; A method comprising:

2. The method of claim 1 , wherein the target charge material comprises a compound of at least one of Ni, Mn, Co, and Al.

3. The method of claim 1 , wherein the halide comprises a fluoride.

4. The leaching solution has a fluoride content in the range of 0.2 to 5 at % before precipitation of the charge material, and Ni on the surface of the charge material particles. ２＋ 10. The method of claim 1, wherein the percentage of ions is increased to between 40.1% and 43.8%.

5. The leaching solution has a fluoride content in the range of 0.2 to 5 at % before precipitation of the charge material, and Co on the surface of the charge material particles. ２＋ 10. The method of claim 1, wherein the percentage of ions is increased from 13.0% to 35.2%.

6. 10. The method of claim 1, further comprising forming the leaching solution to include the target charge material to result in an NCM622 charge material precursor, and wherein the halide comprises a predetermined percentage of fluoride.

7. 10. The method of claim 1, further comprising forming the leach solution from a leach acid selected from the group consisting of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, boric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, and perchloric acid.

8. 10. The method of claim 1, wherein the strong base comprises a precipitating agent selected from the group consisting of sodium hydroxide or potassium hydroxide.

9. 10. The method of claim 1, further comprising determining the predetermined percentage of halide in the leach solution to achieve one or more oxidation states of the target charge material.

10. Nickel, manganese and cobalt (NMC) particles in precursor form for forming an active charge material upon sintering with a lithium compound; 0 at % to 5.0 at % of fluorine impurities in the NMC particles; Holes in the particles resulting from the fluorine impurities wherein each of the particles defines a structure having a surface having nickel ions, and at least 40.1% of the Ni surface ions have an oxidation number of +2.

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