Waste lithium cobalt oxide positive electrode material regenerated through cooperation of lithium lanthanum titanate epitaxial growth and titanium / lanthanum doping and preparation method of waste lithium cobalt oxide positive electrode material
By constructing Li3xLa2/3-xTiO3 epitaxial growth and titanium/lanthanum doping in waste lithium cobalt oxide materials through the sol-gel method, the high energy consumption and pollution problems of traditional recycling methods are solved, and the material performance is restored and improved.
Patent Information
- Application Number
- CN202510973644.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-15
- Publication Date
- 2025-11-11
AI Technical Summary
Traditional methods for recycling waste lithium-ion batteries suffer from high energy consumption, heavy pollution, and incomplete resource recovery. Furthermore, existing recycling technologies have failed to effectively restore material properties.
By utilizing the metastable structural characteristics of waste lithium cobalt oxide materials through the sol-gel method, we achieved epitaxial growth of Li3xLa2/3-xTiO3 and titanium/lanthanum doping, constructed three-dimensional fast ion channels, repaired the material structure, and optimized the electronic structure.
This improved the electrochemical performance and capacity retention of recycled lithium cobalt oxide cathode materials, reduced environmental pollution and carbon emissions, and achieved a super-evolution in material performance.
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Figure CN120933314A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium battery cathode material technology, specifically to a waste lithium cobalt oxide cathode material produced by epitaxial growth of lithium lanthanum titanate in conjunction with titanium / lanthanum doping and regeneration, and its preparation method. Background Technology
[0002] To address the shortage of fossil fuels, lithium-ion batteries, with their efficient and sustainable clean energy storage characteristics, have become a core solution for mobile electronic devices, new energy transportation, and smart grid energy storage systems. However, with the massive amount of waste and environmental pollution caused by their large-scale commercial application, the recycling of spent lithium-ion batteries has become crucial for the sustainable development of the industry.
[0003] Currently, traditional methods for recycling spent lithium-ion batteries mainly include wet recycling and pyrometallurgical recycling. Although these methods are widely used in industry and possess a certain level of recycling efficiency and technological maturity, they suffer from drawbacks such as high energy consumption, heavy pollution, and incomplete resource recovery, which are detrimental to sustainable development. Wet recycling extracts metals through processes such as acid leaching and electrolysis. While it achieves high recovery rates for valuable metals such as cobalt, nickel, and lithium, the process requires large quantities of strong acids and chemical reagents, easily generating secondary pollution such as waste liquid and residue. Pyrometallurgical recycling involves melting spent batteries at high temperatures. Although it has advantages such as a simple process and large-scale processing, it consumes extremely high amounts of energy and emits large amounts of greenhouse gases during operation. Addressing the various problems of traditional recycling methods, direct recycling, due to its advantages of not damaging the intrinsic structure while improving resource utilization, reducing environmental pollution, and lowering carbon emissions, has become key to solving the problem of spent lithium-ion batteries and upholding sustainable development.
[0004] This invention employs a sol-gel method, precisely utilizing the metastable structural characteristics of spent lithium cobalt oxide to achieve a synergistic coupling of material repair and functional upgrading. Specifically, it first utilizes the three-dimensional ion diffusion network formed by the interlayer voids of spent lithium cobalt oxide. The lithium vacancies in this structure not only serve as receiving sites for lithium source refilling but also as sites for La... 3+ and Ti 4+ It provides a dynamic doping channel. The oxygen vacancies and Li-Co antisite defects on its surface exhibit unique thermodynamic activity at high temperatures, leading to surface enrichment and topological condensation reactions in the Li-La-Ti-O system. This results in the epitaxial and uniform growth of 50nm continuous Li₂O₃ from regenerated lithium cobalt oxide. 3x La 2 / 3-x TiO3 core-shell structure. Furthermore, it is affected by Li... 3x La 2 / 3-x TiO3-encapsulated LCO particles achieve a breakthrough in the comprehensive performance of regenerated lithium cobalt oxide materials through a triple mechanism of diffusion channel optimization, electronic structure regulation, and chemical interface protection. Summary of the Invention
[0005] The purpose of this invention is to provide a lithium lanthanum titanate (Li) 3x La 2 / 3-x TiO3 epitaxial growth of regenerated waste lithium cobalt oxide cathode material with synergistic titanium / lanthanum doping and its preparation method. By using a sol-gel method, lithium, titanium, and lanthanum sources are uniformly attached to the material surface, followed by high-temperature sintering. This process simultaneously repairs the material structure and achieves the desired lithium cobalt oxide cathode material. 3x La 2 / 3-x TiO3 epitaxial growth and La 3+ / Ti 4+ Gradient doping. For Li + The extraction and insertion provide a three-dimensional fast ion channel, resulting in a regenerated lithium cobalt oxide cathode material with excellent electrochemical performance.
[0006] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:
[0007] Through the existing crack network and surface vacancy defects of waste lithium cobalt oxide, a three-dimensional crack network is formed under special thermodynamic activity, driving La 3+ / Ti 4+ Gradient doping, La 3+ Ti accumulates near the particle surface, stabilizing the layered structure; 4+ Diffusion into the bulk phase suppresses lattice distortion through the anchoring effect; oxygen vacancies act as electronic defect centers, reducing Li... + Diffusion barrier; Li-Co antisites generate a polarization electric field through local lattice distortion, driving Li + Directed migration to crack network-rich regions provides nucleation sites for epitaxial growth. Compared to traditional methods, this approach achieves direct regeneration of waste lithium cobalt oxide through a triple mechanism of diffusion channel optimization, electronic structure regulation, and chemical interface protection.
[0008] This technical solution achieves simultaneous coupling and dynamic enhancement of repair, doping, and epitaxy through a single high-temperature process: La 3+ / Ti 4+ Gradient doping constructs a stable chemical buffer substrate in the three-dimensional crack network, suppressing lattice collapse while providing a directional template for epitaxial growth; surface oxygen vacancies / Li-Co antisites drive Li + Simultaneously, it induces the directional migration of new Li along the crack network. 3x La 2 / 3-x The TiO3 layer is grown using atomically precise epitaxy, and its lattice continuity reinforces the anchoring effect of doped elements and the integrity of the bulk structure. This three-body synergistic mechanism enables the recycled material to simultaneously achieve defect passivation, interface optimization, and lattice reconstruction during heat treatment, resulting in breakthroughs in capacity, rate capability, and cycle retention. This marks a significant step forward for lithium battery recycling, moving from performance recovery to a stage of performance super-evolution.
[0009] A lithium lanthanum titanate (Li 3x La 2 / 3-x TiO3 epitaxial growth of recycled waste lithium cobalt oxide cathode material with titanium / lanthanum doping. Lithium cobalt oxide is gradient doped with titanium and lanthanum sources to widen the lattice spacing and accelerate the lithium-ion transport rate.
[0010] Lithium cobalt oxide surface epitaxial growth of Li 3x La 2 / 3-x TiO3 core-shell structure, this core-shell structure as Li + Deintercalation of the embedded fast ion channel.
[0011] On the other hand, the present invention proposes Li 3x La 2 / 3-x The preparation method of TiO3 epitaxial growth synergistically with titanium / lanthanum doped recycled waste lithium cobalt oxide cathode material includes the following steps:
[0012] S1: After deep discharge of waste lithium-ion batteries, the positive electrode sheet is disassembled and separated, and placed in a beaker for ultrasonic treatment; after ultrasonic treatment, the lithium cobalt oxide positive electrode material is detached from the aluminum foil and dried in an oven to obtain waste lithium cobalt oxide positive electrode powder.
[0013] S2: Place the waste lithium cobalt oxide cathode powder in a muffle furnace for pretreatment to initially remove residual binder, CEI film and electrolyte;
[0014] S3: Weigh a certain mass of lithium source, titanium source, and lanthanum source according to the corresponding molar ratio, transfer them to anhydrous ethanol, add the corresponding mass of citric acid to the ethanol, and stir at a constant temperature for a certain time using a magnetic stirrer.
[0015] S4: Measure the pH of the S3 solution, adjust the pH with a certain amount of ammonia water, and control the pH within a reasonable range;
[0016] S5: Weigh a certain mass of waste electrode powder from S2 and slowly add it to the S4 solution. Raise the temperature of the magnetic stirrer to a certain temperature and stir at a constant temperature until the solution becomes gel-like. Place it in an oven to dry.
[0017] S6: After thoroughly grinding the material obtained in S5, it is placed in a muffle furnace for three-stage calcination to obtain regenerated lithium cobalt oxide cathode material.
[0018] Furthermore, in step S1, the ultrasonic temperature is 10-80℃ and the time is 40-120min.
[0019] Furthermore, in step S2, the pretreatment temperature of the tubular furnace is 400-650℃, and the treatment time is 2-5 hours.
[0020] Furthermore, in step S3, the lithium source is one of lithium carbonate, lithium hydroxide, or lithium nitrate; the titanium source is one of titanium oxide, titanium isooctanol, or tetrabutyl titanate; and the lanthanum source is one of lanthanum nitrate, lanthanum oxide, or lanthanum hydroxide.
[0021] Furthermore, in step S3, the molar ratio of lithium source, lanthanum source, and titanium source is 3x:(2 / 3-x):1, where x = 0.05-0.15, and the mass of the waste electrode powder weighed is 0.25-5 wt% of that in step S2.
[0022] Furthermore, in step S3, the mass of citric acid is 0.5-5 wt% of the total mass of the lithium source, titanium source, and lanthanum source.
[0023] Furthermore, in step S3, the temperature of the magnetic stirrer is 30-50℃, the magnetic stirring speed is 400-600rpm, and the duration is 30min-120min.
[0024] Furthermore, in step S4, the pH range is controlled between 5 and 8.
[0025] Furthermore, the temperature range in step S5 is 70-80℃.
[0026] Furthermore, in step S6, the heating rate is 2-10℃ / min, the first-stage roasting temperature is 100-150℃, and the processing time is 1-2 hours. The second-stage roasting temperature is 400-600℃, and the processing time is 4-7 hours. The third-stage roasting temperature is 800-1000℃, and the processing time is 4-7 hours.
[0027] On the other hand, the present invention proposes a lithium-ion battery comprising the aforementioned waste lithium cobalt oxide cathode material.
[0028] The beneficial effects of this invention are:
[0029] Based on the pre-existing particle crack network and surface vacancy defects in waste lithium cobalt oxide materials, this three-dimensional interconnected structural defect constructs ion compensation channels and atomic deposition active sites, achieving quantitative backfilling of lithium deficiency and La. 3+ Ti 4+ Gradient doping distribution, and simultaneously, Li driven by lattice matching. 3x La 2 / 3-x Epitaxial growth of TiO3 core-shell structure. This repaired the layered structure of waste lithium cobalt oxide, and La... 3+ Ti 4+ As a structural pillar, it enters the interior of the grain lattice, stabilizing the grain structure and widening the lithium-ion transport channels. Simultaneously, the epitaxially grown Li... 3x La 2 / 3-xThe TiO3 core-shell structure effectively acts as an oxygen diffusion barrier and uses epitaxial strain to stabilize the layered structure, while simultaneously building a three-dimensional fast ion channel for more efficient lithium-ion diffusion, thus improving the electrochemical performance and capacity retention of the recycled material. XRD patterns in Example 1 show that long-term cycling and transitional charge-discharge cycles lead to the collapse of the lithium cobalt oxide structure, lattice oxygen escape, and cobalt dissolution, resulting in the formation of a tri-oxo tetraoxide impurity phase peak. After Li... 3x La 2 / 3-x The cathode material, obtained through TiO3 epitaxial growth and synergistic titanium / lanthanum doping regeneration, shows the disappearance of the impurity phase peaks in lanthanum tetroxide. The XRD pattern perfectly matches the standard card for lithium cobalt oxide.
[0030] Figure 2 SEM image analysis shows that, after Li 3x La 2 / 3-x The lithium cobalt oxide cathode material particles grown by TiO3 epitaxy in conjunction with titanium / lanthanum doping exhibit smooth surfaces and reduced particle cracks. This is because the layered structure of the lithium cobalt oxide material is repaired, which is beneficial for lithium ion extraction and insertion. On the other hand, titanium / lanthanum doping and Li... 3x La 2 / 3-x TiO3 epitaxial growth broadens the lithium-ion transport channels, stabilizes the layered structure of lithium cobalt oxide, inhibits the rapid collapse of the material during charge and discharge, and the Li on the lithium cobalt oxide surface... 3x La 2 / 3-x The core-shell structure of TiO3, as a three-dimensional fast ion channel, accelerates the ion transport rate, improves the electronic conductivity of lithium cobalt oxide materials, and enhances the charge-discharge capability and capacity retention of the materials. Figure 3 and Figure 7 The cycling performance of the recycled lithium cobalt oxide material at a 1C current density was demonstrated. Figure 3 It is Li 3x La 2 / 3-x The TiO3 coating amount is 1 wt% of the waste lithium cobalt oxide. Figure 7 It is Li 3x La 2 / 3-x The TiO3 coating amount was 3 wt% of the waste lithium cobalt oxide. The recycled lithium cobalt oxide material with a coating amount of 1% had a significantly higher first-cycle discharge specific capacity than the recycled lithium cobalt oxide material with a coating amount of 3% (Example 2). Figure 4 and Figure 8 The study demonstrated the rate performance of recycled lithium cobalt oxide materials at 0.1C / 0.2C / 0.5C / 1C / 2C / 5C / 10C and back to 0.1C, further proving that recycled lithium cobalt oxide materials have superior electrochemical performance compared to waste lithium cobalt oxide materials. Furthermore, the electrochemical performance of recycled lithium cobalt oxide materials with a coating of 1% is better than that of recycled lithium cobalt oxide materials with a coating of 3%.
[0031] This invention precisely utilizes the inherent particle cracks and surface oxygen vacancy defects of waste lithium cobalt oxide to provide an ion diffusion path network for quantitative backfilling of structural lithium deficiencies, and synergistically guides La 3+ With Ti 4+ Forming a concentration gradient doping distribution, La 3 + and Ti 4+ Gradient doping broadens the lithium-ion transport channels, stabilizes the layered structure of lithium cobalt oxide, suppresses the rapid collapse of the material during charging and discharging, and simultaneously constructs continuous Li₂ on the surface of lithium cobalt oxide. 3x La 2 / 3-x The TiO3 perovskite core-shell structure, as a three-dimensional fast ion channel, accelerates the ion transport rate and acts as a physical barrier on the particle surface, protecting the particle interior and improving the charge-discharge capability and stability of lithium cobalt oxide materials.
[0032] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description
[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0034] Figure 1 The waste lithium cobalt oxide cathode material and the Li obtained in Example 1 3x La 2 / 3-x TiO3 coating 1% synergistic with La 3 + Ti 4+ XRD pattern of lithium cobalt oxide cathode material after direct regeneration with gradient doping;
[0035] Figure 2 In the diagram, a and b represent waste lithium cobalt oxide cathode material and Li obtained in Example 1, respectively. 3x La 2 / 3-x TiO3 coating 1% synergistic with La 3+ Ti 4+ SEM image of lithium cobalt oxide cathode material after direct regeneration with gradient doping;
[0036] Figure 3 The waste lithium cobalt oxide cathode material and the Li obtained in Example 1 3x La 2 / 3-x TiO3 coating 1% synergistic with La 3 + Ti 4+Cycling performance of lithium cobalt oxide cathode material after direct regeneration with gradient doping at 1C rate;
[0037] Figure 4 The waste lithium cobalt oxide cathode material and the Li obtained in Example 1 3x La 2 / 3-x TiO3 coating 1% synergistic with La 3 + Ti 4+ The rate performance of the lithium cobalt oxide cathode material after gradient doping and direct regeneration at 0.1C, 0.2C, 0.5C, 1C, 2C, 5C and 10C, and then back to 0.1C is shown in the diagram.
[0038] Figure 5 The waste lithium cobalt oxide cathode material and the Li obtained in Example 2 3x La 2 / 3-x TiO3 coating content 3% synergistic with La 3 + Ti 4+ XRD pattern of lithium cobalt oxide cathode material after direct regeneration with gradient doping;
[0039] Figure 6 In the figure, a and b represent the waste lithium cobalt oxide cathode material and the Li obtained in Example 2, respectively. 3x La 2 / 3-x TiO3 coating content 3% synergistic with La 3+ Ti 4+ SEM image of lithium cobalt oxide cathode material after direct regeneration with gradient doping;
[0040] Figure 7 The waste lithium cobalt oxide cathode material and the Li obtained in Example 2 3x La 2 / 3-x TiO3 coating content 3% synergistic with La 3 + Ti 4+ Cycling performance of lithium cobalt oxide cathode material after direct regeneration with gradient doping at 1C rate;
[0041] Figure 8 The waste lithium cobalt oxide cathode material and the Li obtained in Example 2 3x La 2 / 3-x TiO3 coating content 3% synergistic with La 3 + Ti 4+ The rate performance of the lithium cobalt oxide cathode material after gradient doping and direct regeneration at 0.1C, 0.2C, 0.5C, 1C, 2C, 5C and 10C, and then back to 0.1C is shown in the graph. Detailed Implementation
[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0043] Example 1
[0044] The Li described in this embodiment 3x La 2 / 3-x TiO3 epitaxial growth of titanium / lanthanum doped recycled waste lithium cobalt oxide cathode material and its preparation method, including the following steps:
[0045] S1: After deep discharging the waste lithium-ion batteries in sodium chloride solution, disassemble them. Cut the disassembled positive electrode sheet into 8×8cm pieces, place them in a beaker, and perform ultrasonic treatment. The ultrasonic temperature is 30℃, the ultrasonic time is 120min, and the ultrasonic frequency is 100Hz. After ultrasonication, the waste lithium cobalt oxide positive electrode material detached from the aluminum foil is placed in a 120℃ oven and dried for 8h to obtain the waste lithium cobalt oxide positive electrode material.
[0046] S2: Take 10g of waste lithium cobalt oxide cathode powder and put it into a muffle furnace. Pre-treat at 500℃ for 3h to initially remove residual binder, CEI film and electrolyte.
[0047] S3: Mix lithium source, titanium source, and lanthanum source in a molar ratio of 0.3:1:0.576, and weigh out the corresponding mass of 1 wt% of waste lithium cobalt oxide in S5, transfer it to anhydrous ethanol, add 0.5 wt% citric acid of waste lithium cobalt oxide to the ethanol, and place it in a magnetic stirrer for constant temperature stirring at 600 rpm and 50℃ for 2 hours.
[0048] S4: Measure the pH of the S3 solution and adjust the pH using ammonia to control it at around 6.
[0049] S5: Weigh 4g of waste electrode powder from S2 and slowly add it to the S4 solution. Raise the temperature of the magnetic stirrer to 80°C and maintain the temperature while stirring until the solution becomes gel-like. Place it in a 120°C oven to dry.
[0050] S6: After thoroughly grinding the material obtained in S5, it is placed in a muffle furnace for three-stage calcination. The heating rate is 5℃ / min, the first stage calcination temperature is 150℃ and held for 1 hour, the second stage calcination temperature is 500℃ and held for 5 hours, and the third stage calcination temperature is 950℃ and held for 5 hours to obtain the regenerated lithium cobalt oxide cathode material.
[0051] Figure 1Waste lithium cobalt oxide cathode material and Li obtained in Example 1 3x La 2 / 3-x XRD pattern of recycled waste lithium cobalt oxide cathode material with 1% TiO3 coating and synergistic titanium / lanthanum doping. The figure shows Co3O4 impurity peaks at 31.1° and 36.9°, which may be due to an irreversible phase transition caused by the collapse of the layered structure of lithium cobalt oxide during long-term charge-discharge processes. Notably, the directly recycled lithium cobalt oxide cathode material matches the standard diffraction peaks (PDF#75-0532) of lithium cobalt oxide crystals, and the impurity peaks disappear, indicating that the process was successfully carried out using Li-coated lithium cobalt oxide. 3x La 2 / 3-x The lithium cobalt oxide cathode material, which is directly regenerated by TiO3 epitaxial growth and titanium / lanthanum doping, can achieve crystal structure repair, and the titanium / lanthanum doping does not destroy the crystal structure of lithium cobalt oxide.
[0052] Figure 2 SEM images of waste lithium cobalt oxide cathode material and the directly recycled lithium cobalt oxide cathode material obtained in Example 1. Figure 2 a represents the waste lithium cobalt oxide cathode material obtained from dismantling the waste electrode sheet in Example 1. It can be seen that cracks and unevenness appear on the surface of the waste lithium cobalt oxide particles. This is due to structural collapse and interlayer slippage caused by long-term cycling, which is also the culprit for the deterioration of electrochemical performance. Figure 2 b is the product obtained in Example 1 after Li 3x La 2 / 3-x SEM images of lithium cobalt oxide cathode materials regenerated by TiO3 epitaxial growth and titanium / lanthanum doping. After direct regeneration, the structure of the waste lithium cobalt oxide is repaired, the particle surface becomes smooth, and the cracks are significantly reduced. The gradient doping of titanium / lanthanum plays a supporting role, stabilizing the layered structure. The core-shell structure of lithium lanthanum titanate outside the particles provides a three-dimensional fast ion channel for ion transport, improving the overall electrochemical performance of the cathode material.
[0053] Figure 3 The graph shows the cycling performance of a coin cell assembled from waste lithium cobalt oxide material and recycled material obtained in Example 1 at a 1C current density. The first-cycle discharge specific capacity of the waste lithium cobalt oxide material is only 185 mAh g. -1 And after Li 3x La 2 / 3-x The lithium cobalt oxide material, developed through TiO3 epitaxial growth and synergistic titanium / lanthanum doping regeneration, exhibits a capacity of 222.59 mAh g. -1 The discharge specific capacity and the retention rates after 100 cycles were 13.8% and 84.6%, respectively. The improvement in specific capacity and retention rate is mainly attributed to the broadening of lithium-ion diffusion channels by titanium / lanthanum doping. Additionally, the Li+ on the outer surface of the lithium cobalt oxide particles... 3x La 2 / 3-xThe core-shell structure of TiO3 provides a three-dimensional fast ion channel for ion transport, improving the conductivity of the material. Furthermore, the heteroepitaxial layers effectively reduce the occurrence of side reactions in the electrochemical process, significantly improving the capacity retention.
[0054] Figure 4 The graphs show the cycling performance of spent and recycled lithium cobalt oxide materials at different rate operations. Spent lithium cobalt oxide materials exhibit poor rate performance, especially with severe degradation at 10C high current density, resulting in a discharge specific capacity close to zero. In contrast, the recycled material maintains a high discharge specific capacity even during high-rate charge-discharge cycles of 10C. The directly recycled lithium cobalt oxide cathode material exhibits discharge capacities of 217.67, 216.98, 210.03, 201.48, 190.05, 167.55, 137.13, and 209.22 mAh g⁻¹ at 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, 10C, and 0.1C respectively. -1 The specific discharge capacity.
[0055] Example 2
[0056] The Li described in this embodiment 3x La 2 / 3-x TiO3 epitaxial growth of titanium / lanthanum doped recycled waste lithium cobalt oxide cathode material and its preparation method, including the following steps:
[0057] S1: After deep discharging the waste lithium-ion batteries in sodium chloride solution, disassemble them. Cut the disassembled positive electrode sheet into 8×8cm pieces and place them in a beaker for ultrasonic treatment. The ultrasonic temperature is 400℃, the ultrasonic time is 90min, and the ultrasonic frequency is 100Hz. After ultrasonication, the waste lithium cobalt oxide positive electrode material detached from the aluminum foil is placed in a 120℃ oven and dried for 6h to obtain the waste lithium cobalt oxide positive electrode material.
[0058] S2: Take 10g of waste lithium cobalt oxide cathode powder and put it into a muffle furnace. Pre-treat at 600℃ for 3h to initially remove residual binder, CEI film and electrolyte.
[0059] S3: Mix lithium source, titanium source, and lanthanum source in a molar ratio of 0.3:1:0.576, and weigh out the corresponding mass of 3wt% of waste lithium cobalt oxide in S5, transfer it to anhydrous ethanol, add 1wt% citric acid of waste lithium cobalt oxide to the ethanol, and place it in a magnetic stirrer for constant temperature stirring at 500 rpm and 40℃ for 2 hours.
[0060] S4: Measure the pH of the S3 solution and adjust the pH using ammonia to control it at around 6.
[0061] S5: Weigh 4g of waste electrode powder from S2 and slowly add it to the S4 solution. Raise the temperature of the magnetic stirrer to 75°C and maintain the temperature while stirring until the solution becomes gel-like. Place it in a 120°C oven to dry.
[0062] S6: After thoroughly grinding the material obtained in S5, it is placed in a muffle furnace for three-stage calcination. The heating rate is 8℃ / min, the first stage calcination temperature is 150℃ and held for 2 hours, the second stage calcination temperature is 500℃ and held for 5 hours, and the third stage calcination temperature is 950℃ and held for 5 hours to obtain the regenerated lithium cobalt oxide cathode material.
[0063] Figure 5 The waste lithium cobalt oxide cathode material and the Li obtained in Example 2 3x La 2 / 3-x XRD patterns of recycled waste lithium cobalt oxide cathode material with 3% TiO3 coating and synergistic titanium / lanthanum doping. The figures show Co3O4 impurity peaks at 31.34° and 36.8°, which are likely due to an irreversible phase transition caused by the collapse of the layered structure of lithium cobalt oxide during long-term charge-discharge processes. Notably, the directly recycled lithium cobalt oxide cathode material matches the standard diffraction peaks (PDF#75-0532) of lithium cobalt oxide crystals, and the impurity peaks disappear, indicating that the process was successfully carried out using Li-coated lithium cobalt oxide. 3x La 2 / 3-x The lithium cobalt oxide cathode material, which is directly regenerated by TiO3 epitaxial growth and titanium / lanthanum doping, can achieve crystal structure repair, and the titanium / lanthanum doping does not destroy the crystal structure of lithium cobalt oxide.
[0064] Figure 2 SEM images of waste lithium cobalt oxide cathode material and the directly recycled lithium cobalt oxide cathode material obtained in Example 2. Figure 2 a represents the waste lithium cobalt oxide cathode material obtained from dismantling the waste electrode sheet in Example 2. It can be seen that cracks and unevenness appear on the surface of the waste lithium cobalt oxide particles. This is due to structural collapse and interlayer slippage caused by long-term cycling, which is also the culprit for the deterioration of electrochemical performance. Figure 2 b is the product obtained in Example 2 after Li 3x La 2 / 3-x SEM images of lithium cobalt oxide cathode materials regenerated by TiO3 epitaxial growth and titanium / lanthanum doping. After direct regeneration, the structure of the waste lithium cobalt oxide is repaired, the particle surface becomes smooth, and the cracks are significantly reduced. The gradient doping of titanium / lanthanum plays a supporting role, stabilizing the layered structure. The core-shell structure of lithium lanthanum titanate outside the particles provides a three-dimensional fast ion channel for ion transport, improving the overall electrochemical performance of the cathode material.
[0065] Figure 3The graph shows the cycle performance of a coin cell assembled from waste lithium cobalt oxide material and recycled material obtained in Example 2 at a 1C current density. The first-cycle discharge specific capacity of the waste lithium cobalt oxide material is only 195.3 mAh g. -1 And after Li 3x La 2 / 3- x The lithium cobalt oxide material, developed through TiO3 epitaxial growth and synergistic titanium / lanthanum doping regeneration, exhibits a capacity of 220.23 mAh g. -1 The discharge specific capacity and the retention rates after 100 cycles were 61.1% and 90.2%, respectively. The improvement in specific capacity and retention rate is mainly attributed to the broadening of lithium-ion diffusion channels by titanium / lanthanum doping. Additionally, the presence of Li+ on the outer surface of the lithium cobalt oxide particles... 3x La 2 / 3-x The core-shell structure of TiO3 provides a three-dimensional fast ion channel for ion transport, improving the conductivity of the material. Furthermore, the heteroepitaxial layers effectively reduce the occurrence of side reactions in the electrochemical process, significantly improving the capacity retention.
[0066] Figure 4 The graphs show the cycling performance of spent and recycled lithium cobalt oxide materials at different rate operations. Spent lithium cobalt oxide materials exhibit poor rate performance, especially with severe degradation at 10C high current density, resulting in a discharge specific capacity close to zero. In contrast, the recycled material maintains a high discharge specific capacity even during high-rate charge-discharge cycles of 10C. Directly recycled lithium cobalt oxide cathode materials show discharge specific capacities of 215.6, 210.3, 205.3, 195.6, 180.9, 155.3, 105, and 188 mAh g⁻¹ at 0.1C, 0.2C, 0.5C, 1C, 2C, 5C, 10C, and 0.1C, respectively. -1 The specific discharge capacity.
[0067] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims
1. A cathode material for recycled waste lithium cobalt oxide produced by epitaxial growth of lithium lanthanum titanate in conjunction with titanium / lanthanum doping, characterized in that, Regenerated lithium cobalt oxide particles contain La 3+ and Ti 4+ The gradient doped layer is formed through a three-dimensional crack network of waste lithium cobalt oxide; Li is epitaxially grown on the particle surface 3x La 2 / 3-x TiO3 coating layer; The gradient doped layer broadens the lithium-ion transport channels, and the Li 3x La 2 / 3-x TiO3 coating layer serves as a fast ion channel.
2. The lithium cobalt oxide cathode material obtained by epitaxial growth of lithium lanthanum titanate with synergistic titanium / lanthanum doping regeneration as described in claim 1, characterized in that: The LLTO coating layer accounts for 0.25-5 wt% of the total mass of the recycled material.
3. The method for preparing the cathode material as described in claim 1 or 2, characterized in that: Includes the following steps: S1: After deep discharge of waste lithium-ion batteries, the positive electrode sheet is disassembled and separated, and placed in a beaker for ultrasonic treatment; after ultrasonic treatment, the lithium cobalt oxide positive electrode material is detached from the aluminum foil and dried in an oven to obtain waste lithium cobalt oxide positive electrode powder. S2: Place the waste lithium cobalt oxide cathode powder in a muffle furnace for pretreatment to initially remove residual binder, CEI film and electrolyte; S3: Weigh a certain mass of lithium source, titanium source, and lanthanum source according to the corresponding molar ratio, transfer them to anhydrous ethanol, add the corresponding mass of citric acid to the ethanol, and stir at a constant temperature for a certain time using a magnetic stirrer. S4: Measure the pH of the S3 solution, adjust the pH with a certain amount of ammonia water, and control the pH within a reasonable range; S5: Weigh a certain mass of waste electrode powder from S2 and slowly add it to the S4 solution. Raise the temperature of the magnetic stirrer to a certain temperature and stir at a constant temperature until the solution becomes gel-like. Place it in an oven to dry. S6: After thoroughly grinding the material obtained in S5, it is placed in a muffle furnace for three-stage calcination to obtain regenerated lithium cobalt oxide cathode material.
4. The preparation method according to claim 3, characterized in that: In step S1, the ultrasonic temperature is 10-80℃ and the time is 40-120min.
5. The preparation method according to claim 3, characterized in that: In step S2, the pretreatment temperature of the tubular furnace is 400-650℃, and the treatment time is 2-5 hours.
6. The preparation method according to claim 3, characterized in that: In step S3, the lithium source is any one of lithium carbonate, lithium hydroxide, and lithium nitrate; the titanium source is any one of titanium oxide, titanium isooctanol, and tetrabutyl titanate; the lanthanum source is any one of lanthanum nitrate, lanthanum oxide, and lanthanum hydroxide; the molar ratio of the lithium source, lanthanum source, and titanium source is 3x:(2 / 3-x):1, where x = 0.05-0.15, and the mass of the lanthanum source is 0.25-5 wt% of the waste electrode powder in step S2; the mass of citric acid is 0.5-5 wt% of the total mass of the lithium source, titanium source, and lanthanum source.
7. The preparation method according to claim 3, characterized in that: In step S3, the temperature of the magnetic stirrer is 30-50℃, the magnetic stirring speed is 400-600rpm, and the duration is 30min-120min.
8. The preparation method according to claim 3, characterized in that: In step S4, the pH range is controlled between 5 and 8; in step S5, the temperature range is 70-80℃.
9. The preparation method according to claim 3, characterized in that: In step S6, the heating rate is 2-10℃ / min, the first-stage roasting temperature is 100-150℃, and the processing time is 1-2 hours. The second-stage roasting temperature is 400-600℃, and the processing time is 4-7 hours. The third-stage roasting temperature is 800-1000℃, and the processing time is 4-7 hours.
10. A lithium-ion battery, characterized in that: It contains the waste lithium cobalt oxide cathode material as described in claim 1 or 2.