Waste lithium ion battery positive and negative electrode material recovery method based on internal heating type integrated combustion

Abstract

The invention belongs to the technical field of waste lithium ion battery resource recycling, and particularly relates to a waste lithium ion battery positive and negative electrode material recycling method based on internal heating type integrated combustion. The method comprises the following steps: recycling mixed powder of a positive electrode material and negative electrode graphite from the waste battery, compacting the mixed powder in a high-temperature-resistant reaction container, and forming a conductive path by using electrodes at two ends; then, electric energy is applied, generated Joule heat is used as a built-in heat source, self-propagating combustion reaction is triggered instantly, and the temperature of the reaction center can rapidly reach 1380 DEG C or above; at the moment, the crystal structure of the positive electrode material is thoroughly damaged and is reduced into a metal simple substance, an alloy or a simple oxide, and meanwhile, the binder is completely decomposed. According to the method, a traditional external heat source is abandoned, self-heating and self-maintaining of the system are achieved, the method has the outstanding advantages of being extremely low in energy consumption, rapid in reaction, short in process, free of chemical reagent adding and the like, and a brand new path is provided for efficient, green and low-cost recycling of the waste lithium ion battery.

Description

Technical Field

[0001] This invention relates to the field of waste lithium-ion battery resource recycling technology, and in particular to a method for recycling positive and negative electrode materials of waste lithium-ion batteries based on internal heating integrated combustion. Background Technology

[0002] With the global energy structure transformation and the rapid development of the electric vehicle industry, lithium-ion batteries have become the dominant electrochemical energy storage solution due to their advantages such as high energy density, long cycle life, and low self-discharge rate. However, the average lifespan of lithium-ion batteries is typically only 5-8 years, leading to a surge in the number of used lithium-ion batteries.

[0003] Currently, the technical approaches for recycling valuable metals from waste lithium-ion batteries are mainly divided into three categories: physical methods, hydrometallurgical methods, and pyrometallurgical methods.

[0004] Hydrometallurgy is currently the most widely used mainstream process. Its core process is to first disassemble, crush, and sort the battery to obtain "black powder" rich in positive and negative electrode materials. Then, the valuable metal ions in the "black powder" are leached into the solution by inorganic acids (such as hydrochloric acid and sulfuric acid) or organic acids. Various metals are then selectively separated and recovered from the leachate by solvent extraction, chemical precipitation, electrodeposition, and other methods. The advantage of hydrometallurgy is that the metal recovery purity is high and the recovery rate is relatively high. However, this process has significant drawbacks: (1) The process flow is lengthy, involving multiple reaction units and complex operation; (2) It consumes a large amount of chemical reagents such as acids and alkalis, which is costly and easily causes secondary wastewater pollution, resulting in a heavy burden on subsequent wastewater treatment; (3) The leaching process usually requires the addition of reducing agents (such as H2O2) to promote the dissolution of poorly soluble positive electrode materials (such as lithium cobalt oxide), which increases reagent costs and process complexity.

[0005] Pyrometallurgy, often referred to as "high-temperature smelting," involves directly calcining crushed battery materials or enriched cathode materials in a high-temperature furnace at 1300-1500°C for an extended period. During this process, organic matter is burned as a partial energy source, elements such as fluorine and phosphorus are fixed in the slag, while metals like cobalt, nickel, and copper are reduced to form crude alloys, which are then refined. The advantages of traditional pyrometallurgy lie in its large processing capacity and relatively simple requirements for raw material pretreatment. However, its fatal flaw is its extremely high energy consumption, requiring continuous external heating to maintain the high temperature. Furthermore, to lower the melting point and promote slag-metal separation, large amounts of fluxes such as limestone and quartz sand are often added. This not only increases costs but also significantly increases the amount of waste slag, resulting in a substantial loss of lithium elements in the slag that is difficult to recover economically, leading to resource waste.

[0006] In addition, physical methods and other emerging approaches, such as direct remediation and mechanical activation, offer different solutions for recycling. Direct remediation aims to restore the electrochemical performance of cathode materials directly through processes such as lithium replenishment and thermal treatment, enabling the secondary use of materials. However, its success is highly dependent on the consistency of the composition of waste battery materials, making it difficult to effectively handle retired batteries from complex sources and of mixed models in practical applications. On the other hand, while pretreatment methods such as mechanical activation can significantly enhance the leaching effect of subsequent metals by destroying the crystal structure of materials through high-intensity mechanical grinding, they are essentially still an auxiliary and optimization of traditional hydrometallurgical processes, and have not escaped the inherent problems of long processes, high reagent consumption, and potential pollution inherent in hydrometallurgical processes.

[0007] In summary, both existing hydrometallurgical and pyrometallurgical technologies have significant bottlenecks: hydrometallurgy is characterized by "long processes and heavy pollution," while pyrometallurgy suffers from "high energy consumption and difficulty in lithium recovery." Therefore, the industry urgently needs to develop a new recycling technology that is short in process, low in energy consumption, environmentally friendly, and can efficiently recover valuable metals.

[0008] Self-propagating high-temperature synthesis (SHS) technology, as an advanced material synthesis method, utilizes the enormous heat released by the chemical reaction of the reactants themselves to sustain the spontaneous and continuous reaction. This method boasts significant advantages such as low energy consumption, fast reaction rate, and simple equipment. Furthermore, SHS technology has been innovatively applied to the recycling of spent lithium-ion batteries, particularly by cleverly utilizing the battery's own components as built-in "heat generators" and "reducing agents." External electrical energy instantly triggers a violent, internally heated, self-propagating reaction, thereby achieving high-temperature instantaneous reconstruction of the cathode material and efficient recovery of valuable metals. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for recycling positive and negative electrode materials of waste lithium-ion batteries based on internal heating integrated combustion. This method utilizes the inherent characteristics of the internal components of the battery to achieve rapid, low-energy recycling with a short process flow.

[0010] To achieve the above objectives, the present invention adopts the following technical solution.

[0011] This invention provides a method for recycling positive and negative electrode materials from spent lithium-ion batteries based on internally heated integrated combustion, comprising the following steps: S1: Raw material preparation: Discharge, disassemble, crush and screen the waste lithium-ion batteries to obtain active material powder that is a mixture of positive electrode material and negative electrode material. S2: Loading and Forming: The active material powder, which is a mixture of positive and negative electrode materials, is ball-milled and activated. Then, the active material powder is placed in a high-temperature resistant reaction vessel and a dense conductive path is formed inside the vessel. S3: Power-on triggers self-propagating reaction: Apply DC or pulse voltage to both ends of the conductive path, and utilize the conductivity of the negative electrode graphite in the mixed powder to generate Joule heat in the entire path instantly, with the temperature rising sharply to over 1000°C, triggering a self-propagating high-temperature ablation reaction. S4: Product processing: After the reaction is completed, the product is cooled to obtain a loosely structured sintered block. The sintered block is then ground and pulverized, and then leached in dilute acid to achieve the separation and recovery of valuable metals.

[0012] In this invention, in step S1, the waste lithium-ion battery is selected from one or more of lithium cobalt oxide batteries, lithium iron phosphate batteries, and ternary lithium batteries.

[0013] In this invention, in step S1, after disassembling the positive and negative electrode sheets from the waste lithium-ion battery, they are cut into small pieces and placed in a vertical grinder for mixing and crushing. After crushing, the mixture is passed through a 200-mesh sieve to obtain an active material powder consisting of a mixture of positive and negative electrode materials. The mass ratio of the positive electrode material to the negative electrode material in the mixed active material powder remains the same as the original ratio after battery disassembly.

[0014] In this invention, in step S2, the high-temperature resistant reaction vessel is a quartz tube, and the conductive path is formed by: compacting the mixed powder inside the quartz tube and pressing it from both ends with conductive electrodes to ensure circuit continuity; the conductive electrodes are brass electrodes, and the circuit is connected to an external power source through a tungsten wire.

[0015] In this invention, in step S2, the ball milling speed is 200~400 rpm and the ball milling time is 3-5h.

[0016] In this invention, in step S3, the self-propagating combustion reaction is carried out under an inert atmosphere.

[0017] In this invention, in step S3, the applied voltage is between 5 and 50V, and the energizing time is between 30 and 300 seconds. More preferably, the applied voltage is between 10 and 30V, and the energizing time is between 60 and 120 seconds.

[0018] In this invention, in step S3, due to the excellent conductivity of the negative electrode graphite, a large current will instantly pass through the entire material system. The pulse current is between 0.2-50A, generating a violent Joule heating effect, causing the material temperature to rise rapidly within tens of seconds, thereby triggering a self-propagating combustion reaction; the temperature of the self-propagating reaction can reach above 1380℃. Under ultra-high temperature conditions, the layered or olivine-like crystal structure of the positive electrode material collapses rapidly and is reduced and decomposed into elemental metals, alloys, or simple oxides such as Ni, Co, and Mn. Simultaneously, the internal binder, PVDF, and other organic materials undergo high-temperature decomposition and vaporization. The partial combustion of the negative electrode graphite provides additional heat and generates a reducing atmosphere, promoting the reduction of the positive electrode material.

[0019] In this invention, in step S4, the particle size of the sample obtained after grinding and pulverizing the sintered block is between 0.03 and 0.15 mm, the dilute acid is hydrochloric acid with a concentration of 1 to 3 mol / L, the leaching temperature is 150 to 200 °C, and the leaching time is 60 to 90 min.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: Extremely low energy consumption: It makes full use of the conductivity and flammability of graphite in the negative electrode of the battery as the internal "fuel" and "heat source" of the reaction. External electrical energy is only used to "ignite" the reaction, which greatly reduces energy consumption.

[0021] Rapid reaction: The self-propagating reaction process is very fast, and the entire high-temperature reaction is completed within minutes, which greatly shortens the processing time and improves efficiency.

[0022] Process simplification: High temperature completely destroys the structure of the cathode material, making it extremely easy to handle, which simplifies the subsequent separation and leaching process and reduces reagent consumption.

[0023] Environmentally friendly: Organic matter is completely decomposed at high temperatures, avoiding the generation of harmful gases and reducing wastewater discharge in hydrometallurgy.

[0024] Simple equipment: The required devices are simple, the cost is low, and it is easy to scale up for industrialization. Attached Figure Description

[0025] Figure 1 The image shows the XRD pattern obtained by processing LiFePO4 cathode material powder using the self-propagating high-temperature Joule thermal shock technology in Example 1 of this invention.

[0026] Figure 2 The image shows the XRD pattern obtained by processing LiCoO2 cathode material powder using the self-propagating high-temperature Joule thermal shock technology in Example 2 of this invention. Detailed Implementation

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] This invention provides a method for recycling positive and negative electrode materials from spent lithium-ion batteries based on internally heated integrated combustion. The method includes the following steps: discharging, disassembling, and peeling the spent batteries to obtain a mixed powder of positive electrode material and negative electrode graphite; directly placing it in a high-temperature resistant reaction vessel and compacting it, using the electrodes at both ends to form a conductive path; then applying electrical energy, utilizing the conductivity of the negative electrode graphite in the mixture to generate Joule heat as an internal heat source, instantly initiating an integrated self-propagating combustion reaction involving both positive and negative electrode materials, with the reaction center temperature rapidly reaching over 1380℃; under this ultra-high temperature environment, the crystal structure of the positive electrode material is completely destroyed, reduced to metallic elements, alloys, or simple oxides, while the organic binder is completely decomposed. This method eliminates the need for traditional external heating sources, achieving self-heating and self-sustaining of the system. It has outstanding advantages such as extremely low energy consumption, rapid reaction, short process, and no need to add chemical reagents, providing a new path for the efficient, green, and low-cost recycling of spent lithium-ion batteries.

[0029] The apparatus for implementing the above method in this invention includes: High-temperature resistant reaction vessel: used to hold reaction materials; the high-temperature resistant reaction vessel is a quartz tube; A pair of conductive electrodes: disposed opposite each other at both ends of the reaction vessel, used to compress the material and conduct current; the conductive electrodes are brass electrodes; High-power power supply: connected to the conductive electrode, used to provide the electrical energy required to initiate the self-propagating reaction; the high-power power supply is a vertical self-propagating device; Wires: connect high-power power supplies and conductive electrodes; the wires are tungsten wires; Cooling system: Used to rapidly cool the products after a self-propagating combustion reaction.

[0030] The following are specific examples.

[0031] Example 1

[0032] The recycling targets are used lithium iron phosphate batteries.

[0033] Raw material preparation: After the battery is discharged and disassembled, the positive and negative electrode plates are cut into small pieces of 2cm×3cm, mixed and crushed by a vertical grinder, and passed through a 200-mesh sieve to obtain a mixed powder whose main components are lithium iron phosphate and graphite.

[0034] Loading: Weigh the mixed powder and load it into a quartz tube, then gently vibrate to compact it. Insert two brass electrodes from both ends and press the powder firmly. Connect the electrodes to a DC power supply with a maximum output of 50V / 50A via tungsten wires.

[0035] Reaction: When the power is turned on, the material heats up and turns red rapidly, initiating a self-propagating reaction. The reaction proceeds rapidly from the front end to the other end. The applied voltage is 10V, and the energizing time is 90 seconds. The current during the reaction is between 0.2 and 50A.

[0036] Product analysis: A black, porous sintered block was obtained after the reaction. Figure 1 The image shows the XRD pattern obtained from the self-propagating high-temperature Joule thermal shock technology used in Example 1 of this invention to process LiFePO4 cathode material powder. X-ray diffraction analysis indicates that the main phases in the product are Li2O and Fe2P. The sintered block was ground and leached with 1 mol / L dilute hydrochloric acid at 200°C for 90 min. After the reaction, the solution was filtered, diluted (concentration within the detection range), parameters were set, the sample was introduced, plasma was excited, and spectral signals were acquired. Calculation results show that the lithium leaching rate reached 93.59%, far exceeding the efficiency of directly leaching the original lithium iron phosphate powder.

[0037] Example 2

[0038] The recycling targets are used mobile phone lithium cobalt oxide batteries.

[0039] Raw material preparation: After the battery is discharged and disassembled, the positive and negative electrode plates are cut into small pieces of 2cm×3cm, mixed and crushed by a vertical grinder, and passed through a 200-mesh sieve to obtain a mixed powder whose main components are lithium cobalt oxide and graphite.

[0040] Loading: Weigh the mixed powder and load it into a quartz tube, then gently vibrate to compact it. Insert two brass electrodes from both ends and press the powder firmly. Connect the electrodes to a DC power supply with a maximum output of 50V / 50A via tungsten wires.

[0041] Reaction: When the power is turned on, the material heats up and turns red rapidly, initiating a self-propagating reaction. The reaction proceeds rapidly from the front end to the other end. The applied voltage is 15V, and the energizing time is 60 seconds. During the reaction, the current is between 0.2 and 50A.

[0042] Product analysis: A black, porous sintered block was obtained after the reaction. Figure 2 The image shows the XRD pattern obtained from the self-propagating high-temperature Joule thermal shock technology used in Example 2 of this invention to process LiCoO2 cathode material powder. X-ray diffraction analysis indicates that the main phases in the product are CoO and Co metal. After grinding and pulverizing the sintered block, it was leached with 1 mol / L dilute hydrochloric acid at 200°C for 90 min. The leaching rate of lithium reached 91.00%, and the leaching rate of cobalt reached 98.10%, which is much higher than the efficiency of directly leaching the original lithium cobalt oxide powder.

[0043] Example 3

[0044] The recycling targets are used ternary lithium batteries.

[0045] Raw material preparation: After the battery is discharged and disassembled, the positive and negative electrode plates are cut into small pieces of 2cm×3cm, mixed and crushed by a vertical grinder, and passed through a 200-mesh sieve to obtain a mixed powder whose main components are nickel, cobalt, manganese and graphite.

[0046] Loading: Weigh the mixed powder and load it into a quartz tube, then gently vibrate to compact it. Insert two brass electrodes from both ends and press the powder firmly. Connect the electrodes to a DC power supply with a maximum output of 50V / 50A via tungsten wires.

[0047] Reaction: When the power is turned on, the material heats up rapidly, initiating a self-propagating reaction. The reaction proceeds rapidly from one end to the other. The applied voltage is 15V, and the energizing time is 60 seconds. During the reaction, the current is between 0.2 and 50A.

[0048] Product Analysis: A black, porous sintered block was obtained after the reaction. X-ray diffraction analysis showed that the ternary material was decomposed into Ni, Co, and Mn metal alloy particles and oxides, while lithium existed as Li₂CO₃, facilitating subsequent separation and recovery. After grinding and pulverizing the sintered block, it was leached with 1 mol / L dilute hydrochloric acid at 200℃ for 90 min. The recovery rates were 94.66% for lithium, 91.28% for cobalt, 91.08% for nickel, and 92.32% for manganese.

[0049] Example 4

[0050] The recycling targets are waste lithium iron phosphate batteries, waste ternary lithium batteries, and waste lithium cobalt oxide batteries.

[0051] Raw material preparation: After the battery is discharged and disassembled, the positive and negative electrode plates are cut into small pieces of 2cm×3cm, mixed and crushed by a vertical grinder, and passed through a 200-mesh sieve to obtain active material powder that is a mixture of positive and negative electrode materials.

[0052] Loading: Weigh the mixed powder and load it into a quartz tube, then gently vibrate to compact it. Insert two brass electrodes from both ends and press the powder firmly. Connect the electrodes to a DC power supply with a maximum output of 50V / 50A via tungsten wires.

[0053] Reaction: When the power is turned on, the material heats up rapidly, initiating a self-propagating reaction. The reaction proceeds rapidly from one end to the other. The applied voltage is 15V, and the energizing time is 120 seconds. The current during the reaction is between 0.2 and 50A.

[0054] Product Analysis: A black, porous sintered block was obtained after the reaction. X-ray diffraction analysis showed that the mixed powder was decomposed into Ni, Co, and Mn metal alloy particles and oxides, while lithium existed as Li₂CO₃, facilitating subsequent separation and recovery. After grinding and pulverizing the sintered block, it was leached with 1 mol / L dilute hydrochloric acid at 200℃ for 90 min. The recovery rates were 94.45% for lithium, 93.61% for cobalt, 94.99% for nickel, and 91.36% for manganese.

[0055] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for recycling positive and negative electrode materials of waste lithium-ion batteries based on internal heat type integrated combustion, characterized in that, The method comprises the following steps: S1: raw material preparation: discharging, disassembling, crushing and screening treatment of waste lithium ion batteries to obtain active material powder mixed with positive and negative materials; S2: loading and forming: the active material powder mixed with positive and negative materials is subjected to ball milling activation treatment, and then the active material powder is placed in a high-temperature resistant reaction container and forms a dense conductive path in the container; S3: electrically induced self-propagating reaction: a direct current or pulse voltage is applied to both ends of the conductive path, and the conductive property of the negative graphite in the mixed powder is used to generate Joule heat in the entire path instantaneously, and the temperature is rapidly increased to above 1000℃, thereby initiating a self-propagating high-temperature ablation reaction; S4: product treatment: after the reaction is completed, a sintered block with a loose structure is obtained by cooling, and the sintered block is ground and crushed, and then leaching in dilute acid is performed to realize separation and recovery of valuable metals.

2. The method according to claim 1, wherein, In step S1, the waste lithium ion battery is selected from one or more of lithium cobaltate battery, lithium iron phosphate battery or ternary lithium battery. 3.The method according to claim 1, characterized in that, In step S1, after the positive and negative electrode sheets are disassembled from the waste lithium ion battery, they are cut into small pieces and mixed and crushed in a vertical grinder, and then sieved through a 200-mesh sieve to obtain active material powder mixed with positive and negative materials.

4. The method according to claim 1, wherein, In step S2, the high-temperature resistant reaction container is a quartz tube, and the conductive path is formed by compacting the mixed powder in the quartz tube and pressing it tightly from both ends with conductive electrodes to ensure the conduction of the circuit.

5. The method according to claim 4, wherein the method is characterized by, The conductive electrode is a brass electrode, and the circuit is connected to an external power source through a tungsten wire. 6.The method of claim 1, wherein the method further comprises: separating the positive electrode material and the negative electrode material from the waste lithium ion battery; and drying the positive electrode material and the negative electrode material. In step S2, the ball milling speed is 200-400 rpm, and the ball milling time is 3-5h.

7. The method according to claim 1, wherein the method is characterized by, In step S3, the applied voltage is between 5-50V, and the power-on time is 30-300 seconds. 8.The method according to claim 1 or 6, characterized in that, In step S3, the applied voltage is between 10-30V, and the power-on time is 60-120 seconds. 9.The method of claim 1, wherein the method further comprises, after the step of separating the cathode active material from the anode active material, a step of separating the cathode active material from the anode active material. In step S3, the pulse current in the self-propagating reaction is between 0.2-50A, and the instantaneous temperature reaches above 1380℃. 10.The method of claim 1, wherein the method further comprises the step of: In step S4, the particle size of the sample obtained after the sintered block is ground and crushed is between 0.03-0.15mm, the dilute acid is 1-3mol / L concentration of hydrochloric acid, the leaching temperature is 150-200℃, and the leaching time is 60-90min. ​

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