A method for repairing and regenerating waste lithium ion battery ternary material single crystals

Abstract

The application discloses a method for single-crystal regeneration of waste lithium ion battery ternary material, which comprises the following steps: after the invalid lithium ion battery ternary material is dissolved by ultrasonic wave in dilute acid, lithium source and transition metal source are added according to the element ratio of the ternary oxide of a target product, ball milling and tabletting are sequentially performed, and then pure oxygen calcination is performed, so that the single-crystal lithium ion battery ternary material is obtained. The single-crystal regeneration and quality improvement of the positive oxide material of the invalid lithium ion battery are realized, and the method has the advantages of high efficiency, short cycle and low energy consumption, and is beneficial to the repair process.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of waste lithium ion battery ternary material single crystal repair regeneration method, especially to a kind of failure particle micro-acid dissociation, tablet calcination is realized to failure anode material single crystal regeneration method, belong to waste battery recycling technical field. BACKGROUND

[0002] At present, the main treatment means of waste battery is to realize the effective extraction of key elements in waste battery through disassembly, crushing, separation, extraction and purification means. However, the traditional pyrometallurgical process has problems such as high energy consumption, and the wet treatment method inevitably needs to go through acid and alkali treatment process. In addition, due to the complicated and long process, the utilization rate of key metal elements is not good. Therefore, the development of short process high value application of failed lithium ion battery is of great importance to resource guarantee, value-added efficiency and environmental protection in China.

[0003] At present, in view of the series of problems existing in pyrometallurgical process and wet process, researchers have proposed direct repair technology for regenerated battery materials. By using the special crystal phase of original failed materials, direct recovery is carried out to break through the traditional process barrier of "material-element-material" and create a high value process of "material-material". At present, for the failed ternary material, the main methods are simple lithium sintering method, molten salt sintering method, hydrothermal lithium supplement technology and electrochemical lithium supplement technology. Among them, the simple lithium sintering technology has problems such as uneven sintering and uneven lithium supplement effect; while the other three repair methods have problems such as high cost and high energy consumption. In addition, the traditional lithium supplement recovery means is only to realize the recovery of failed materials. However, there are many types of ternary materials at present, and the types of waste batteries disassembled from unified battery packs are different. The repaired materials obtained by simple recovery repair may also have different crystal systems. Moreover, the secondary particle depolymerization of the failed ternary material is serious, and there are a large number of primary small particles after the depolymerization of the failed battery black powder. The D50 of the ternary material after repair cannot meet the needs of the industry, and it is difficult to enter the commodity circulation.

[0004] Therefore, it is very important to develop single crystal repair technology for failed ternary electrode materials and break through the last link of failed material flow to commercial industry for the closed-loop recycling of waste batteries. SUMMARY

[0005] In order to improve the problem that it is difficult to handle polycrystalline and single crystal mixed phase materials in the repair process of waste lithium ion battery ternary battery material in the prior art, the purpose of the present application is to provide a regeneration method for dissociation and single crystal of mixed ternary material. The method is simple and efficient, and only needs to carry out dilute acid ultrasonic dissociation of failed ternary anode material to induce polycrystalline to single crystal transformation and combine tabletting and pyrometallurgical regeneration process operation, which can be realized.

[0006] To achieve the above technical purposes, the application provides a method for regenerating single-crystal ternary materials from waste lithium ion batteries, which comprises the following steps: subjecting the failed lithium ion battery ternary material to ultrasonic dissociation in dilute acid, adding lithium source and transition metal source according to the element ratio of the target product ternary oxide, sequentially performing ball milling and tabletting, and then performing calcination in pure oxygen to obtain single-crystallized lithium ion battery ternary material; the transition metal source is at least one of nickel source, cobalt source and manganese source.

[0007] The key technical solution of the application is to first subject the obtained failed ternary positive electrode material to ultrasonic dissociation in dilute acid to induce the transformation of polycrystals in the ternary material into single-crystal particles, while the single-crystal structure is not affected; then, according to the element ratio of the target single-crystal material, the ratio between the failed material and lithium is adjusted to promote the key elements; then, the powder is tabletted to promote the migration of key elements between the failed materials; finally, the fire regeneration is performed in a pure oxygen atmosphere to realize the regeneration of single-crystal uniform ternary material from polycrystal-single-crystal failed ternary mixed waste.

[0008] The inventors have found that the calcination in a pure oxygen atmosphere can ensure that the oxides in the material are fully oxidized, thereby promoting the improvement of crystallinity and electrochemical performance. In addition, the calcination in a pure oxygen atmosphere can also reduce the residual organic matter in the material and avoid the formation of carbides in the material, thereby improving the cycle stability and safety of the material.

[0009] As a preferred scheme, the failed lithium ion battery ternary material comprises failed polycrystal ternary material and / or failed single-crystal ternary material. The ternary material in the application can be a series of nickel-cobalt-manganese electrode materials.

[0010] As a preferred scheme, the dilute acid is at least one of hydrochloric acid, sulfuric acid, nitric acid, citric acid, acetic acid and oxalic acid.

[0011] As a preferred scheme, the concentration of the dilute acid is 0.01-1.0 mol / L. Too low acid concentration is difficult to induce the grain boundary deactivation and dissociation of polycrystal ternary material; and too high acid concentration will quickly promote the dissolution of the ternary material body, causing damage to the body structure of the ternary material. Further preferably, the concentration is 0.05-0.8 mol / L. More preferably, the concentration is 0.1-0.3 mol / L.

[0012] As a preferred scheme, the solid-liquid ratio of the failed lithium ion battery ternary material and the dilute acid is 1 g:(1-5) mL.

[0013] As a preferred solution, the nickel source is at least one of nickel-containing hydroxide, oxide, nitrate, carbonate and organic salt; the cobalt source is at least one of cobalt-containing hydroxide, oxide, nitrate, carbonate and organic salt; and the manganese source is at least one of manganese-containing hydroxide, oxide, nitrate, carbonate and organic salt. The organic salt is further preferably citrate and acetate.

[0014] As a preferred solution, the ultrasonic dissociation condition is that the power is 100-240 W and the time is 1-60 min. The ultrasonic time of the present application directly affects the repair effect. If the ultrasonic time is too short, the failed ternary polycrystalline material is difficult to dissociate; and if the ultrasonic time is too long, the lithium element near the surface of the ternary material will be removed, affecting the repair effect. The ultrasonic time is further preferably 5-40 min. The ultrasonic time is more preferably 10-30 min.

[0015] As a preferred solution, the density control of the tablet is 3.0-10.0 g / cm 3 . The control of the tablet density is another key factor for the regeneration of the present application. If the tablet density is too low, the contact between the powder materials will not be close, resulting in a long element migration path between the powder materials, and finally resulting in a pure phase of the regenerated particles, which is difficult to generate a single and pure phase of the regenerated structure, and the electrochemical performance is poor. If the tablet density is too high, the contact strength between the powder material particles will be too large, resulting in the agglomeration of the generated material, and the particle size of the generated material is not uniform. The tablet density is further preferably 4.0-9.0 g / cm 3 . The tablet density is more preferably 5.0-8.0 g / cm 3 .

[0016] As a preferred solution, the calcination is pre-fired at 330-350℃ for 4-6h, and then sintered at 780-800℃ for 10-12h. The present application removes the crystal water in the material through the low-temperature pre-firing process, and induces the initial shrinkage of the volume of the material, thereby increasing the temperature transmission rate in the high-temperature calcination process and improving the uniformity of the crystal phase and particle size of the material in the high-temperature calcination process. After the material obtained by calcination is ground, broken and classified, a single-crystal regenerated and uniformized material can be obtained.

[0017] Compared with the prior art, the technical solution of the present application has the following beneficial technical effects:

[0018] 1) The regeneration method provided by the present application can realize the transformation of the failed ternary positive electrode material polycrystal / single crystal mixed waste of the waste lithium ion battery into a single-crystal uniformized regenerated material. The method is simple to operate, short in cycle, strong in adaptability for batch repair of mixed ternary waste, and has a capacity and cycle performance comparable to commercial single-crystal ternary material after repair and regeneration.

[0019] 2) The present application utilizes the dilute acid to induce the polycrystal in the mixed crystal phase ternary waste material, and the element migration between the failed materials is promoted by combining the tabletting operation, so that the single crystal homogenized ternary material is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The scanning electron microscope image of the single crystal material after repair of Example 1.

[0021] Figure 2 The scanning electron microscope image of the single crystal material after repair of Example 3.

[0022] Figure 3 The charge and discharge platform diagram of the single crystal material after repair of Example 1.

[0023] Figure 4 The charge and discharge platform diagram of the single crystal material after repair of Example 5.

[0024] Figure 5 The high-resolution transmission electron microscope image of the single crystal material after repair of Example 3, and it can be clearly seen from the figure that the material has a single crystal structure. DETAILED DESCRIPTION

[0025] The following examples are used to illustrate the present application, but not to limit the scope of the present application.

[0026] The failed positive electrode material powder of the lithium ion battery used in the present application is obtained by precise or broken disassembly, and the positive electrode material black powder can be purchased on the market.

[0027] After testing by ICP, the difference between the element ratio of the failed positive electrode mixed material and the element ratio of the target ternary material is calculated, and the elements are supplemented.

[0028] The liquid-solid ratio of the examples and comparative examples of the present application is: 1g of failed ternary material, 1ml of dilute acid solution, mass / volume ratio 1(g) / 1(ml).

[0029] Example 1

[0030] 1) The failed polycrystal / single crystal mixed ternary waste material is immersed in a 0.5mol / L nitric acid solution, ultrasonically dissociated for 20min at 120W, and then filtered, and the obtained powder is dried.

[0031] 2) The dried ternary dissociated powder is supplemented with lithium carbonate, nickel acetate, cobalt acetate, and manganese acetate (i.e. nickel / cobalt / manganese acetate) according to the element ratio of the target crystal phase (811), and then ball milled;

[0032] 3) The ball milled powder material is subjected to tabletting operation, and the tabletting density is 6.0g / cm 3 .

[0033] 4) The obtained tablets are calcined under pure oxygen atmosphere, pre- calcined at 350°C for 6h, and calcined at 800°C for 12h. After grinding, crushing and grading, the preliminary repaired ternary material is obtained.

[0034] Example 2

[0035] The difference between this example and Example 1 is only that the concentration of nitric acid is replaced by 0.1 mol / L, and the other steps and conditions are consistent.

[0036] Example 3

[0037] The difference between this example and Example 1 is only that the concentration of nitric acid is replaced by 1 mol / L, and the other steps and conditions are consistent.

[0038] Example 4

[0039] The difference between this example and Example 1 is only that the ultrasonic dissociation time is replaced by 1 min, and the other steps and conditions are consistent.

[0040] Example 5

[0041] The difference between this example and Example 1 is only that the ultrasonic dissociation time is replaced by 60 min, and the other steps and conditions are consistent.

[0042] Example 6

[0043] The difference between this example and Example 1 is only that the tablet density is controlled to be 3.0 g / cm 3 , and the other steps and conditions are consistent.

[0044] Example 7

[0045] The difference between this example and Example 1 is only that the tablet density is controlled to be 10.0 g / cm 3 , and the other steps and conditions are consistent.

[0046] Example 8

[0047] The difference between this example and Example 1 is only that the added lithium source is replaced by an equal amount of lithium hydroxide, and the other steps and conditions are consistent.

[0048] Example 9

[0049] The difference between this example and Example 1 is only that the added transition metal source is replaced by an equal amount of nickel carbonate, cobalt carbonate, and manganese carbonate (i.e., nickel / cobalt / manganese carbonates), and the other steps and conditions are consistent.

[0050] Example 10

[0051] The embodiment differs from Example 1 only in that the dilute acid is replaced by oxalic acid of the same concentration, and the remaining steps and conditions are consistent.

[0052] Example 11

[0053] The embodiment differs from Example 1 only in that the dilute acid is replaced by citric acid of the same concentration, and the remaining steps and conditions are consistent.

[0054] Comparative Example 1 (without dilute acid dissociation and tabletting)

[0055] The failed multi-crystal / single-crystal mixed ternary waste material is subjected to element proportioning (at a ratio of 811), lithium carbonate, nickel acetate, cobalt acetate, and manganese acetate are added, and after ball milling, calcination is performed under a pure oxygen atmosphere, pre-burning is performed at 350°C for 6h, and calcination is performed at a temperature of 800°C for 12h, and after the obtained material is ground, broken, and classified, a preliminarily repaired ternary material is obtained.

[0056] Comparative Example 2 (without tabletting)

[0057] The failed multi-crystal / single-crystal mixed ternary waste material is subjected to element proportioning after ultrasonic dissociation in a 0.5mol / L nitric acid solution for 20min, lithium carbonate, nickel acetate, cobalt acetate, and manganese acetate are added, and after ball milling, calcination is performed under a pure oxygen atmosphere, pre-burning is performed at 350°C for 6h, and calcination is performed at a temperature of 800°C for 12h, and after the obtained material is ground, broken, and classified, a preliminarily repaired ternary material is obtained.

[0058] Comparative Example 3 (without dilute acid dissociation)

[0059] The failed multi-crystal / single-crystal mixed ternary waste material is subjected to element proportioning, lithium carbonate, nickel acetate, cobalt acetate, and manganese acetate are added, and after ball milling, calcination is performed, and material tablet density control is performed (tablet density is 6.0g / cm 3 ), and finally the obtained tablet is calcined under a pure oxygen atmosphere, pre-burning is performed at 350°C for 6h, and calcination is performed at a temperature of 800°C for 12h, and after the obtained material is ground, broken, and classified, a preliminarily repaired ternary material is obtained.

[0060] Discharge effect examination

[0061] 1) Preparation of sample

[0062] The failure battery material in each embodiment and comparative example is black powder obtained from market. The failure material, acetylene black, polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 8 / 1 / 1, and a certain amount of NMP is added to prepare a uniform slurry. The obtained slurry is coated on an aluminum foil, and then placed in a vacuum oven at 100°C for 24h drying. The obtained electrode sheet is cut by a slicing machine into small round pieces with a diameter of 1cm to become the obtained positive electrode material, wherein the copper foil has more than 1mg of active material loaded on it.

[0063] The obtained positive electrode sheet, electrolyte, lithium sheet, battery shell, separator, etc. are placed in an argon glove box for battery assembly. After sealing, the obtained battery is a assembled button cell.

[0064] Note: All examples and comparative examples are prepared by using the above electrode material preparation method.

[0065] 2) Test method

[0066] After the obtained button cell is placed for 12h, it is placed on a blue electric test channel for electrochemical performance test, wherein the current density is set to 0.2Ag -1 , and the voltage interval is set to 2.6-4.3V, etc. The obtained data is directly displayed on the blue electric tester, which can be directly taken.

[0067] 3) Test results: see Table 1

[0068] Table 1: Types of organic salts in pickling process, sintering conditions and test results of each example and comparative example

[0069]

[0070]

[0071] Note: The failure material to be repaired in the table is a ternary polycrystal / single crystal mixed material.

[0072] The sintering condition is calcination under pure oxygen atmosphere, precalcination at 350°C for 6h, and calcination at 800°C for 12h.

[0073] The results of Table 1 show that:

[0074] From the data comparison of Example 1 and Comparative Examples 1-3, it can be seen that when no tabletting or dilute acid dissociation is performed, the capacity of the repaired ternary material decreases.

[0075] From the data comparison of Examples 1-3, it can be seen that as the dilute acid concentration increases, the capacity of the repaired material first increases and then decreases. This is mainly because too high dilute acid concentration may cause loss of the bulk structure of the ternary material.

[0076] From the data comparison of Example 1 and Examples 4-5, it can be seen that with the increase of ultrasonic time, the capacity of the repair material presents a trend of first increasing and then decreasing, which is mainly because the lithium element near the surface of the ternary material will be removed when the ultrasonic time is too long, which affects the repair effect.

[0077] From the data comparison of Example 1 and Examples 6-7, it can be seen that with the increase of the tablet density, the capacity of the repair material presents a trend of first increasing and then decreasing, which is mainly because the tablet density is too large, which will cause the contact strength between the powder material particles to be too large, resulting in the agglomeration of part of the generated material, which affects the repair effect.

[0078] From the data comparison of Example 1 and Examples 8-11, it can be seen that when the types of dilute acid, lithium source and transition metal source change, good repair effect can be achieved.

[0079] The single crystal material repaired according to Example 1 and Example 5 is tested according to the test method of step 2), and the results are shown in Figure 3 and Figure 4 . The results show that the performance of the failed material can be restored to the level comparable to the commercial 811 single crystal material (the first capacity of the commercial 811 single crystal material is 190 mAh g -1 , and the capacity of the material remains 168 mAh g -1 after 100 cycles at a current density of 0.2 Ag -1 .

Claims

1. A method for recycling spent lithium-ion battery ternary material monocrystallization, characterized in that: The single-crystal lithium ion battery ternary material is obtained by the following steps: after the failed lithium ion battery ternary material is ultrasonically dissociated by dilute acid, lithium source and transition metal source are added according to the element ratio of the target product ternary oxide, ball milling and tabletting are sequentially performed, and then pure oxygen calcination is performed. The transition metal source is at least one of a nickel source, a cobalt source and a manganese source; The failed lithium ion battery ternary material includes failed polycrystal ternary material and / or failed single-crystal ternary material; The concentration of the dilute acid is 0.01-1.0 mol / L; The solid-liquid ratio of the failed lithium ion battery ternary material and the dilute acid is 1g:(1-5)mL; The dilute acid is nitric acid; The density of the compressed tablet is controlled to be 5.0-8.0 g / cm 3 ; The ultrasonic dissociation condition is: power is 100-240W, and time is 10-30min; The calcination is pre-burned at 330-350℃ for 4-6h, and then sintered at 780-800℃ for 10-12h.

2. The single-crystal regeneration method of the waste lithium ion battery ternary material according to claim 1, characterized in that: The nickel source is at least one of nickel-containing hydroxide, oxide, nitrate, carbonate and organic salt; The cobalt source is at least one of cobalt-containing hydroxide, oxide, nitrate, carbonate and organic salt; The manganese source is at least one of manganese-containing hydroxide, oxide, nitrate, carbonate and organic salt.

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