Method for producing hydrogen and oxygen and recycling fluorine through electrolysis of waste batteries

Abstract

The invention relates to a method for electrolytic production of hydrogen and oxygen and recovery of fluorine by using waste batteries, which comprises the following steps: mixing lime or quicklime with water to prepare lime water or quicklime mixed liquor as an electrolytic medium for electrolytic reaction; the method comprises the following steps: putting a charged scrapped battery or battery pack into an electrolytic bath, injecting an electrolytic medium, starting an electrolysis process, decomposing water by virtue of the charged characteristic of the battery and the synergistic effect of the electrolytic medium, generating hydrogen by a negative electrode and generating oxygen by a positive electrode; collecting hydrogen and oxygen; the lithium hexafluorophosphate in the battery electrolyte reacts with water to generate HF, and the HF reacts with Ca (OH) 2 or CaO in the electrolytic medium again to generate fluorite CaF2; and a fluorite CaF2 product is obtained through precipitation separation. The waste batteries can be safely treated without pre-discharging, hydrogen, oxygen and fluorine resources are recovered at the same time, and the problems that in the prior art, resources are wasted, efficiency is low, and fluorine cannot be recovered are solved.

Description

Technical Field

[0001] This invention relates to a method for producing hydrogen, oxygen, and other recycled fluorine by electrolysis of waste batteries. Background Technology

[0002] Currently, 3C, power, and energy storage lithium batteries are all charged during recycling, with voltages generally exceeding 3.0V, posing significant safety risks to subsequent dismantling. The industry currently employs two main methods: one is to use specialized equipment to discharge the batteries, which is time-consuming, wasteful of resources, and requires substantial equipment investment; the other is to discharge them by immersing them in a water tank, but this method cannot recover the fluorine and hydrogen and oxygen produced during electrolysis, resulting in the waste of these scarce resources.

[0003] In existing technologies, the recycling of waste batteries faces both efficiency and cost issues in the discharge process, as well as the lack of fluorine and hydrogen resource recovery. There is an urgent need for a technical solution that can simultaneously solve the discharge problem and efficiently recover resources. Summary of the Invention

[0004] The purpose of this invention is to provide a method for producing hydrogen, oxygen, and other recyclable fluorine by electrolyzing spent batteries. This method safely processes spent batteries without pre-discharging them, while simultaneously recovering hydrogen, oxygen, and fluorine resources, thus solving the problems of resource waste, low efficiency, and inability to recover fluorine in existing technologies.

[0005] To achieve the above objectives, the technical solution adopted by this invention is as follows: A method for producing hydrogen, oxygen, and other recovered fluorine by electrolysis of waste batteries, comprising the following steps: (1) Electrolysis medium preparation: Mix lime or quicklime with water to prepare lime water or quicklime mixture, which is used as the electrolysis medium for the electrolysis reaction; (2) Electrolysis reaction implementation: Place the charged waste battery or battery pack into the electrolytic cell, inject the electrolytic medium from step (1), start the electrolysis process, and achieve water decomposition by means of the battery's own charged characteristics and the synergistic effect of the electrolytic medium. Hydrogen is generated at the negative electrode and oxygen is generated at the positive electrode. (3) Gas collection and storage: collecting hydrogen and oxygen; (4) Fluorine resource recovery: HF generated by the reaction of lithium hexafluorophosphate in the battery electrolyte with water, and HF reacts again with Ca(OH)2 or CaO in the electrolyte to generate fluorite CaF2. (5) Fluorite separation and recovery: Taking advantage of the physical property that fluorite CaF2 is insoluble in water, the mixed liquid in the electrolytic cell is introduced into the sedimentation tank, and the fluorite CaF2 product is obtained through sedimentation separation.

[0006] Based on the fact that the theoretical decomposition potential of water is 1.23V, and that an electrolytic reaction can occur at approximately 1.55V after superimposing an overpotential, this invention selects lime water or a mixture of quicklime as the electrolytic medium. This medium can meet the reaction requirements for the electrolytic production of hydrogen and oxygen, and can also react with HF generated inside the battery to produce recyclable fluorite (CaF2).

[0007] In step (2), while the charged waste battery or battery pack is being electrolyzed, the charged waste battery or battery pack is also being destroyed to allow the internal Li to be released. + With hydroxide ions (OH-) in lime water - The reaction produces lithium hydroxide (LiOH), thereby increasing the electrolytic efficiency.

[0008] One way to destroy a charged, discarded battery or battery pack is to drill a hole in the battery with an electric drill so that the electrolyte inside the battery can flow out smoothly.

[0009] Furthermore, in step (2), the temperature during the electrolysis reaction is 40–60°C. This temperature range can reduce the viscosity of the solution, increase the ion mobility, and thus optimize the electrolysis effect.

[0010] In step (2), a mechanical stirrer is used to stir the electrolysis process to prevent local concentration unevenness, reduce electrode concentration polarization, and ensure the stable progress of the electrolysis reaction.

[0011] In step (1), deionized water is preferably used to prepare the electrolysis medium to reduce impurity ions such as chloride ions (Cl). - ), sulfate ions (SO4²) - To prevent interference from impurity ions such as ions, and to prevent side reactions from occurring at the anode.

[0012] In step (1), if the water used contains chlorine, the water can be pre-electrolyzed to remove chlorine ions.

[0013] To produce more hydrogen, in step (1), 0.05M nickel chloride (NiCl2) and / or 0.05M nickel sulfate (NiSO4) can be added as catalysts to reduce the hydrogen evolution overpotential and improve the hydrogen generation efficiency.

[0014] In step (3), after collecting hydrogen and oxygen, they are separated and collected according to their density difference, and then stored in corresponding pressure vessels. The beneficial effects of this invention are: 1. Utilizing the charged characteristics of batteries to generate safe power: The charged state of used batteries (voltage > 3.0V) is no longer a safety hazard, but rather an auxiliary condition for the electrolysis reaction. By utilizing the conductivity of the electrolytic medium (lime water / quicklime mixture), the electrolysis reaction of water can be directly triggered (the voltage required for electrolysis is only about 1.55V, lower than the initial battery voltage). This allows the battery to naturally consume electrical energy during the reaction, eliminating the need for additional discharge operations and avoiding incomplete discharge or potential safety risks during the discharge process.

[0015] 2. Liquid medium isolates risks and ensures process safety: The lime water / quicklime mixture in the electrolytic cell is an inert conductive medium. On the one hand, it can isolate the air from contact with the active materials inside the battery (such as lithium, cobalt, etc.) to prevent oxidation and heat release; on the other hand, it can absorb trace amounts of harmful gases that may be generated during electrolysis, and at the same time buffer the slight leakage and swelling of the battery that may occur, so as to avoid the spread of risks.

[0016] 3. Medium stability ensures reaction safety: A mixture of lime water and quicklime was chosen as the electrolysis medium, rather than pure water. The medium is weakly alkaline, which can neutralize the HF generated by the reaction of lithium hexafluorophosphate and water in the battery electrolyte, thus preventing acid corrosion of the electrolytic cell and leakage. The dielectric has stable conductivity, which can avoid "local high temperature" caused by excessive local resistance during electrolysis and prevent the battery from overheating and catching fire.

[0017] 4. Safe conversion of HF reaction: The highly toxic HF gas generated by the reaction of lithium hexafluorophosphate with water is not directly emitted, but reacts instantly with Ca(OH)2 / CaO in the electrolytic medium to generate stable solid fluorite (CaF2). The toxicity of HF is completely eliminated through chemical reaction, and fluorite is insoluble in water and non-corrosive, so there is no secondary risk in the subsequent precipitation and recovery process.

[0018] 5. Enhance recycling value: Simultaneously recycle hydrogen, oxygen, and fluorite (CaF2). Hydrogen can be used as a core raw material for hydrogen energy, and fluorite is a key basic raw material for fluorochemicals, realizing the transformation of waste batteries into valuable resources.

[0019] 6. Reduced processing costs: No additional investment in discharge equipment is required, eliminating the discharge process, shortening the processing cycle, and reducing equipment and time costs.

[0020] 7. Achieving resource recycling: For the first time, efficient recovery of fluorine from waste batteries has been achieved, supplementing the supply of fluorine resources and contributing to the sustainable development of the fluorochemical industry.

[0021] 8. Enhanced safety performance: It avoids the safety risks of directly disassembling charged batteries. The electrolysis process and subsequent reactions are carried out in a controlled environment, improving the safety of waste battery disposal. Detailed Implementation

[0022] The present invention will be further illustrated below with reference to the embodiments, but the embodiments do not limit the present invention in any way.

[0023] The electrolytic cell uses DSA anodes and nickel cathodes with an electrode spacing of 1–2 cm.

[0024] The electrolysis process of this invention: The main component of saturated limewater is Ca(OH)2, and the following reaction occurs during electrolysis: Anode (reduction reaction):

[0025] Mainly produces hydrogen and OH. - The alkalinity of the solution increases.

[0026] Cathode (oxidation reaction): or (If it contains chloride ions).

[0027] It usually produces oxygen, but if the water contains chlorine (such as tap water), it may produce chlorine gas.

[0028] Overall reaction (ignoring impurities):

[0029] Calcium hydroxide itself does not participate in the main reaction, but it affects the conductivity of the solution and the electrode process.

[0030] Example 1 A method for producing hydrogen, oxygen, and other recovered fluorine by electrolysis of spent batteries includes the following steps: (1) Electrolysis medium preparation: Lime or quicklime is mixed with water to prepare lime water or quicklime mixture, which serves as the medium for the electrolysis reaction. Deionized water is preferred for preparing the electrolysis medium to reduce impurity ions such as Cl-. - SO4² - Interference, to prevent anodic side reactions.

[0031] Tap water can also be used, but because the water contains chlorine, it needs to be pre-electrolyzed to remove chlorine ions.

[0032] (2) Electrolysis reaction implementation: The charged waste battery or battery pack is directly placed into the electrolysis cell, the electrolytic medium prepared in step (1) is injected, and the electrolysis process is started. The battery's own charged characteristics, together with the electrolytic medium, realize the decomposition of water. Hydrogen is generated at the positive electrode and oxygen is generated at the negative electrode.

[0033] While electrolyzing charged, discarded batteries or battery packs, the charged batteries or battery packs are also subjected to destructive treatment to allow the internal Li to be released. + With OH in lime water- The reaction produces LiOH, which increases the electrolytic rate and improves the electrolysis efficiency.

[0034] During electrolysis, a mechanical stirrer is used to prevent uneven concentration in certain areas and reduce concentration polarization at the electrodes.

[0035] The temperature during the electrolysis reaction is controlled at 60°C.

[0036] (3) Gas collection and storage: Collect hydrogen and oxygen from the electrolytic cell, and then separate and collect them according to the density difference between hydrogen and oxygen, and store them in the corresponding pressure vessels.

[0037] (4) Fluorine resource recovery: HF generated by the reaction of lithium hexafluorophosphate in the electrolyte with water reacts with Ca (OH)2 or CaO in the electrolyte medium to generate fluorite CaF2.

[0038] (5) Fluorite separation and recovery: Taking advantage of the physical property that fluorite CaF2 is insoluble in water, the mixed liquid in the electrolytic cell is introduced into the sedimentation tank, and the fluorite CaF2 product is obtained through sedimentation separation.

[0039] Example 2 Unlike implementation 1: (1) Electrolysis medium preparation: Mix lime or quicklime with water to prepare lime water or quicklime mixture, and add 0.05M NiCL2 as a catalyst to reduce hydrogen evolution overpotential.

[0040] In this embodiment, adding 0.05M NiSO4, or 0.05M NiCL2 and 0.05M NiSO4 can also achieve the catalytic purpose.

[0041] Comparative Example 1 Unlike Example 1, ordinary tap water was used as the electrolyte.

[0042] Comparative Example 2 The difference from Example 1 is: (2) Electrolysis reaction implementation: The charged waste battery or battery pack is directly placed into the electrolysis cell, the electrolytic medium prepared in step (1) is injected, and the electrolysis process is started. The battery's own charged characteristics, together with the electrolytic medium, realize the decomposition of water. Hydrogen is generated at the positive electrode and oxygen is generated at the negative electrode.

[0043] (4) Fluorine resource recovery: After the electrolysis reaction is completed, a hole is drilled in the battery with a power tool so that the HF generated by the reaction of lithium hexafluorophosphate and water inside the battery reacts again with Ca(OH)2 or CaO in the electrolytic medium to generate fluorite CaF2.

[0044] Comparison table of hydrogen production from waste lithium batteries using mixed limewater solution.

Claims

1. A method for producing hydrogen, oxygen, and recovering fluorine by electrolysis of spent batteries, characterized in that, Includes the following steps: (1) Electrolysis medium preparation: Mix lime or quicklime with water to prepare lime water or quicklime mixture, which is used as the electrolysis medium for the electrolysis reaction; (2) Electrolysis reaction: The charged waste battery or battery pack is placed in the electrolysis cell, the electrolysis medium of step (1) is injected, the electrolysis process is started, and the water is decomposed by means of the battery’s own charged characteristics and the synergistic effect of the electrolysis medium. Hydrogen is generated at the negative electrode and oxygen is generated at the positive electrode. (3) Gas collection and storage: collecting hydrogen and oxygen; (4) Fluorine resource recovery: HF generated by the reaction of lithium hexafluorophosphate in the battery electrolyte with water, and HF reacts again with Ca(OH)2 or CaO in the electrolyte to generate fluorite CaF2. (5) Fluorite separation and recovery: The mixture in the electrolytic cell is introduced into a sedimentation tank for precipitation and separation to obtain fluorite CaF2 product.

2. The method for producing hydrogen, oxygen, and recovering fluorine by electrolysis of waste batteries according to claim 1, characterized in that, In step (2), while the charged waste battery or battery pack is being electrolyzed, the charged waste battery or battery pack is being destroyed so that the lithium ions inside react with the hydroxide ions in the lime water to generate lithium hydroxide.

3. The method for producing hydrogen, oxygen, and recovering fluorine by electrolysis of waste batteries according to claim 2, characterized in that, The method of destroying the charged, discarded battery or battery pack involves drilling holes in the battery with an electric drill.

4. The method for producing hydrogen, oxygen, and recovering fluorine by electrolysis of waste batteries according to claim 1, characterized in that, In step (2), the temperature during the electrolysis reaction is 40–60°C.

5. The method for producing hydrogen, oxygen, and recovering fluorine by electrolysis of waste batteries according to claim 2, characterized in that, In step (2), a mechanical stirrer is used to stir the electrolysis process to prevent local concentration unevenness, reduce electrode concentration polarization, and ensure the stable progress of the electrolysis reaction.

6. The method for producing hydrogen, oxygen, and recovering fluorine by electrolysis of waste batteries according to claim 1, characterized in that, In step (1), deionized water is used to prepare the electrolytic medium.

7. The method for producing hydrogen, oxygen, and recovering fluorine by electrolysis of waste batteries according to claim 1, characterized in that, In step (1), if the water used contains chlorine, the water is pre-electrolyzed to remove chlorine ions.

8. The method for producing hydrogen, oxygen, and recovering fluorine by electrolysis of waste batteries according to claim 1, characterized in that, In step (1), 0.05M nickel chloride and / or 0.05M nickel sulfate are added as catalysts to reduce the hydrogen evolution overpotential and improve the hydrogen generation efficiency.

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